METHOD FOR OBTAINING COMMERCIAL FEED JUICES HAVING A MORE HAND-SQUEEZED CHARACTER

Abstract: A method for obtaining commercial feed juices having textural, aroma and flavor properties more like hand-squeezed orange juice is disclosed. This method involves gentle extraction of orange fruit with commercial juice extractors, gentle and quick removal of rag, seeds and peel from the extracted juice, substantially complete removal of sensible pulp, and removal of at least some of the sinking pulp. The feed juices obtained have a relatively low viscosity and sinking pulp level, minimized levels of peel oil and flavanoid glycosides and a relatively high ratio of more desirable orange compounds to less desirable orange compounds.

Description: TECHNICAL FIELD This application relates to commercially processed orange juice products which are closer to hand-squeezed orange juice in character than current commercial products. This application particularly relates to a method for obtaining commercial feed juices useful in preparing such products. For many people, the "gold standard" of orange juice beverages is freshly hand-squeezed orange juice. Hand-squeezed orange juice has many properties which are desirable to the consumer. These properties include the color and hue of the juice, its foaming characteristics, and the appearance of floating, intact juice sacs. In addition, hand-squeezed orange juice has a particularly pleasing, fruity aroma and flavor character. Hand-squeezed orange juice also has unique textural characteristics. Somewhat surprisingly, hand-squeezed juice exhibits pseudoplastic behavior, i.e. is "shear-thinning." This pseudoplastic behavior is especially apparent at shears associated with sipping and swallowing of orange juice. For example, hand-squeezed juice from Florida Valencia oranges has a relatively low average viscosity of from 4 to 6 mPas (4 to 6 centipoise) (measured at 8°C) at shear rates of 10 to 100 sec⁻¹ which approximate the shear of sipping and swallowing. This unique drinking texture of orange juice is believed to be controlled by at least two different factors. One is the amount of background or "sinking" pulp present in hand-squeezed juice. This sinking pulp, while fairly small in size (i.e., passes through a 20 mesh screen), influences significantly the viscosity of orange juice. The other is the relatively low levels of pectin and hesperidin, the major flavanoid glycoside present in the pulp, peel and rag. The cloud in orange juice contains an assemblage of needle-like hesperidin crystals stuck together with pectin. It is believed that this assemblage of hesperidin and pectin influences, to a lesser extent than sinking pulp, the viscosity of orange juice. The unique properties and characteristics of hand-squeezed orange juice result, in large part, from how it is made. Hand-squeezing involves fairly gentle extraction of juice from the orange fruit. This gentle extraction minimizes the introduction of off-flavor compounds, as well as materials which adversely affect color and texture. In particular, hand-squeezing prevents the introduction of significant levels of peel oil and other off-flavors which can impart a bitter flavor character to the juice. Hand-squeezing also minimizes the grinding of juice sacs into viscosity-increasing sinking pulp. There is also typically less abrasion of the rag and albedo portion of the peel which contain off-flavor components, as well as hesperidin glycosides and soluble pectin. Hand-squeezing oranges is not a practical way to generate commercial quantities of orange juice. The yield of juice from orange fruit by using hand squeezers is fairly low, typically on the order of about 80-90%. Even if commercial quantities of juice could be extracted by hand-squeezing, it would not be economical to distribute it in that form. Hand-squeezed orange juice contains about 85 to about 90% water. The most economical way to store and distribute orange juice is in concentrated form. Indeed, the bulk of orange juice commercially processed in the United States exists in concentrate form. Another factor which would make distribution of hand-squeezed orange juice impractical is its lack of storage stability. Hand-squeezed juice contains pectinesterase enzymes which can demethoxylate pectins present in the juice. These demethoxylated pectins can form undesirable jellified lumps over time which increase the viscosity of the juice. In addition, because hand-squeezed juice has a relatively high water activity, it is subject to microbial spoilage in a relatively short time period unless pasteurized. Commercially processed orange juice products have tried to approach the quality of hand-squeezed orange juice. These attempts have not been completely successful. The lack of hand-squeezed character in commercially processed juice products is due in large part to the quality of the starting feed juice. Current commercial feed juices contain significant levels of undesirable components or contaminants which are very difficult, or impossible, to remove during subsequent juice processing. In commercial operations, the quality of the starting feed juice is determined by essentially two factors. One is the quality of the fruit which is used. The use of over-ripe, immature or very small fruit can contribute undesirable flavor compounds and contaminants to the feed juice. The other, more significant factor is the equipment used in juice extraction and finishing, in particular the conditions under which this equipment is operated. Operating conditions usually involve a compromise between quality of the juice and the yield of juice from the orange fruit. Generally, the higher the quality of the feed juice, the lower will be the yield, and vice versa. Accordingly, targeting a feed juice to have the characteristics of hand-squeezed orange juice is not an easy choice, given the potential adverse economics of a low juice yield. Even if the feed juice approaches hand-squeezed quality, further commercial processing can adversely affect its properties. The characteristic "fresh" compounds of freshly hand-squeezed orange juice include the low molecular weight alcohols (e.g., ethanol and methanol), aldehydes (e.g., acetaldehyde) and esters (e.g., ethyl butyrate and ethyl 3-hydroxyhexanoate). Since these compounds are relatively volatile, they can be easily lost due to volatilization. In addition, these delicate compounds, as well as other less volatile compounds such as valencene are easily degraded during evaporative heat concentration processes typically used to remove the bulk of water from the feed juice. One method for preserving these delicate aroma and flavor volatiles is to strip them from the feed juice before evaporative concentration. One such process is disclosed in European patent application 110,638 to Powers et al, published June 13, 1984. In the Powers et al process, the feed juice is stripped with steam or inert gas to remove orange aroma/flavor volatiles. These stripped volatiles are then condensed at progressively colder temperatures preferably in the range of 35° to -46°C (95° to -50°F). The resulting aroma/flavor condensate is separated by centrifugation to provide an aqueous stripper essence and a stripper oil. The stripper essence and stripper oil are subsequently added back to the concentrated stripped juice. The Powers et al process is basically preservative in nature. This means that whatever volatiles are stripped out of the feed juice will be essentially present in the stripper essence or stripper oil. This includes off-flavor volatile components as well. Accordingly, the quality of the feed juice can determine greatly the quality of the resulting stripper essence and stripper oil obtained by the Powers et al process. After the delicate aroma and flavor volatiles have been removed from the feed juice, it is then concentrated. Most commercial concentration processes utilize heat evaporation techniques to remove the bulk of water from the juice. In addition to removing water, these evaporative processes also serve additional functions. One important function is to deactivate enzymes present in the juice, in particular pectinesterase. The standard evaporative system for concentrating feed juice utilizes temperature accelerated short-time evaporators (TASTE). TASTE evaporators concentrate by heating a flowing film of the feed juice with steam or vapor previously generated from the feed juice. In a standard seven-stage, four-effect TASTE evaporator system, the feed juice is heated at progressively higher temperatures, starting at 40°C, and passing through a maximum evaporative temperature of 96°C, followed by heating at progressively lower temperatures ending at 40°C where the concentrated juice attains a solids level of 63° Brix. See Nagy et al, Citrus Science and Technology , Vol. 2 (1977), pp. 217-218. TASTE evaporative systems can impart cooked off-flavors to the resulting concentrated orange juice. This is due to a combination of relatively long times (minutes) to which the juice is subjected to relatively high temperatures, e.g. as high as 96°C. TASTE concentrates (58° to 72° Brix) derived from current commercial Florida feed juices can also have viscosities of from about 8000 to about 20000 mPas (about 8,000 to about 20,000 centipoise) at 8°C. Even when these TASTE concentrates are diluted to single strength, they have viscosities much higher than that of hand-squeezed orange juice. BACKGROUND ART A. Selection of processable fruit Nagy et al, Citrus Science and Technology , Vol. 2, (1977), pp. 183-189, contains a general description of how citrus fruit is prepared for processing. Nagy et al teaches that during sorting, badly damaged, softened, over-ripe or otherwise low quality or unwholesome fruit is removed by hand during sorting of fruit. This reference also states that "fruit may be stored in bins for 12 to 72 hours before processing." When referring to mechanically harvested fruit, Nagy et al say the fruit should be handled as quickly as possible to minimize the time between harvesting and juicing. Ranganna et al, "Citrus Fruits. Part II. Chemistry, Technology and Quality Review., B. Technology," CRC Critical Reviews in Food Science and Nutrition , Vol. 19 (1983), pp. 4-5, also gives a general description of the handling and sorting of citrus fruit before processing. Ranganna et al state that unwholesome fruit must be removed before processing. This reference also states that, after washing, the fruit is inspected again to remove damaged fruit missed earlier or subsequently damaged. B. Extraction and finishing of juice Nagy et al, supra , at pp. 188-99, gives a general description of juice extraction and finishing as it applies to the citrus industry. Nagy et al teach that the juice finisher and extractor are important to the nature, quality and characteristics of the citrus juice or concentrate, and can be adjusted to control the amount of pulp, oil, etc., in the juice. This reference specifically refers to the Brown model 400 and 700 juice extractors as producing a high quality juice that is very low in peel oil content. Ranganna et al, supra , at pp. 6-7, also provide a general description of juice extraction and finishing. Ranganna et al teaches that the setting and operation of the juice extractor and finisher determines the yield of the juice and its quality characteristics. They state that the goal is to remove as much juice as possible from the fruit without grinding the pulp or membrane or extracting oil and juice from the peel. This reference also indicates that the pressure exerted during extraction of the juice has a significant effect on its quality and that excessive pressures produce juice having higher contents of bitter limonin, total pectin, serum viscosity, oxygenation of terpenes and aldehydes from the flavedo, septa, and seeds, etc. Conversely, juice extracted with less pressure has higher color values and better flavor. U.S. Patent 4,518,621 to Alexander, issued May 21, 1985 , discloses a juice finisher for removing solids from extracted juice. In this finishing machine, extracted juice is introduced into a rotating cylindrical screen. The centrifugal force generated urges the fluid portion of the juice outwardly through the screen while retaining the solids. A plurality of paddles are arranged for rotation within the screen to uniformly spread the juice along the inside surface thereof to facilitate separation. This finisher is alleged to separate the fluid portion of the juice from the solids in "a relatively gentle manner" and "without harsh mechanical pressure being applied against", the juice entering the finisher. The main benefit alleged is the prevention of solid components from being forced through the screen. U.S. Patent 3,385,711 to Sperti, issued May 28, 1968 , discloses the production of orange juice and orange juice concentrates which remain palatable throughout reasonable periods of storage under proper storage conditions. This patent states that the development of bitterness in juice products is due to pulp present in the juice. This bitterness problem is prevented by separating the pulp from the extracted juice by centrifuging, filtering or decanting and then adding pulp which does not develop undesired bitterness characteristics. SUMMARY OF THE INVENTION The invention is concerned with a method for preparing a commercial feed juice from orange fruit which comprises the processes of juice extraction from selected fruit (I), removal of rag and seed (II), separation of feed juice from pulp (III), and removing some of the sinking pulp (IV). It is important that the juice is extracted yields a titratable peel oil level of 0.006% to 0.015%, which can be achieved by using a Low Oil Juice extractor or a commercial juice extractor with a prior de-oiling step. Rag and seed are removed within 3 minutes, the sensible pulp (ie pulp > 0.5mm) is removed to provide a juice having at least 10% sinking pulp (ie pulp <0.5mm), and finally, the level of sinking pulp that remains in the feed juice is reduced to between 5 and 10%. BRIEF DESCRIPTION OF DRAWING The Figure shows schematically a preferred evaporative concentration system used with the present invention. A. Obtaining Feed Juice from Orange Fruit A key aspect of the present invention is the starting feed juices obtained from orange fruit. The physical and chemical composition of these feed juices is unique, especially compared to current commercial feed juices. However, the textural, aroma and flavor properties of these unique feed juices are such that they are more like hand-squeezed orange juice. Surprisingly, preferred feed juices of the present invention (titratable peel oil content of about 0.010% or less) have been found to be equally preferred to hand-squeezed juice, when obtained from the same variety of orange fruit (e.g. Valencia orange fruit). By comparison, current commercial feed juices have been found to be significantly dispreferred relative to hand-squeezed juice. These "more like hand-squeezed orange juice" characteristics are important to the textural, aroma and flavor properties of orange juice products prepared from the unique feed juices of the present invention. In addition, the particular physical and chemical composition of these unique feed juices is highly important to subsequent processing, including aroma and flavor volatile stripping and evaporative concentration. Surprisingly, these high quality feed juices can be obtained at commercially acceptable juice yields (at least about 90%) when using the feed juice processing techniques to be described hereafter. This is contrary to current belief in the orange juice industry that high quality feed juice can only be obtained at much lower juice yields and vice versa. The unique feed juices of the present invention can be obtained from either Valencia orange fruit or non-Valencia orange fruit. As used herein, "Valencia orange fruit" refers to orange fruit from the genotype or variety Valencia which usually mature late in the respective harvest season and typically have a relatively high peel oil content. Examples of suitable Valencia fruit include Florida Valencia fruit, California Valencia fruit and Brazilian Valencia fruit. Juice extracted from Valencia fruit, especially Florida Valencia, tends to have a stronger "fresh" aroma/flavor character and a thinner, less pulpy texture. As used herein, "non-Valencia orange fruit" refers to all remaining orange fruit which usually matures in the early to middle part of the harvest season and typically has a relatively low peel oil content. Examples of suitable non-Valencia fruit include the Florida Early/Midseason oranges (Hamlin, Parson Brown and Pineapple), Brazilian varieties such as Pera Rio and Natal, as well as tangerines, mandarin oranges, blood oranges and navel oranges. Juice extracted from non-Valencia orange fruit tends to have a less strong "fresh" aroma/flavor character and a thicker, more pulpy texture compared to that extracted from Valencia fruit. An important characteristic of the feed juices of the present invention is their viscosity. Selection of the "right" viscosity for the feed juice has been found to be particularly critical to achieving a "more like hand-squeezed juice" texture for the ultimate orange juice product. For example, orange juice products prepared from feed juices having too low a viscosity will be characterized as "watery" or "thin" in texture. By comparison, current, higher viscosity, commercial feed juices lead to orange juice products having a "thicker" mouthfeel unlike that of hand-squeezed orange juice. In addition, it has been found that feed juice viscosity has important effects on juice yield and subsequent evaporative concentration of the feed juice. For example, a feed juice having too low a viscosity usually means an unacceptable loss of juice yield. By contrast, a feed juice having too high a viscosity can make it extremely difficult, or impossible, to evaporatively concentrate the feed juice and can cause excessive generation of cooked off-flavor. For these reasons, feed juices of the present invention have relatively low viscosities. The particular viscosity of the feed juice (when measured at 8°C) depends on the orange fruit from which it is derived. Generally, feed juices of the present invention obtained from non-Valencia fruit have lower viscosities than those obtained from Valencia fruit. For feed juices obtained from non-Valencia fruit, the viscosity is about 8 mPas (8 centipoise) or less. Typically, non-Valencia feed juices have a viscosity of from about 5 to about 8 mPas (about 5 to about 8 centipoise), preferably from about 6 to about 7 mPas (about 6 to about 7 centipoise). For feed juices obtained from Valencia fruit, the viscosity is about 10 mPas (10 centipoise) or less. Typically, Valencia feed juices have a viscosity of from about 7 to about 10 mPas about (7 to about 10 centipoise), preferably from about 8 to about 9 mPas (about 8 to about 9 centipoise). Feed juices having these viscosities for the indicated orange fruit permit the preparation of orange juice products having textural properties more like hand-squeezed juice without significantly affecting juice yield or the ability to effectively concentrate the feed juice by the evaporative process. (The method for measuring the viscosity of feed juices of the present invention is described hereafter in part B of this application.) Another key characteristic of feed juices of the present invention is their level of sinking pulp. As used herein, "sinking pulp" refers to insoluble materials present in the juice which have a particle size less than about 0.5 mm. Sinking pulp usually results from the shredding or cutting of juice sacs into much finer particles. The level of sinking pulp has a particularly important effect on the viscosity of the feed juice. Generally, as the level of sinking pulp increases, the viscosity of the feed juice likewise increases. In addition, the level of sinking pulp can be an indicator of how gently the feed juice was extracted and finished. Generally, the more gentle the extraction and finishing steps, the lower the level of sinking pulp. Other factors affecting the level of sinking pulp include the condition of the fruit (especially freeze damage) and its physical handling prior to extraction. The level of sinking pulp is desirably minimized in feed juices of the present invention. The particular sinking pulp level of the feed juice depends on the orange fruit from which it is derived. Generally, feed juices of the present invention obtained from non-Valencia fruit have less sinking pulp than those obtained from Valencia fruit. For feed juices obtained from non-Valencia fruit, the level of sinking pulp is about 8% or less. Typically, non-Valencia feed juices have sinking pulp level of from about 5 to about 8%, preferably from about 6 to about 7%. For feed juices obtained from Valencia fruit, the level of sinking pulp is about 10% or less. Typically, Valencia feed juices have a sinking pulp level of from about 7 to about 10%, preferably from about 8 to about 9%. (The method for measuring the sinking pulp level of feed juices of the present invention is described hereafter in part E of this application.) Another important characteristic of feed juices of the present invention is their level of titratable peel oil. The level of peel oil can be an important indicator of how carefully the juice was extracted from the orange fruit, especially fruit which has not been deoiled. Generally, the lower the level of peel oil (and other peel contaminants) present in the feed juice, the more gentle is the extraction of the juice from the orange fruit. It is desirable in the feed juices of the present invention to minimize the level of titratable peel oil. The level of titratable peel oil in these feed juices is about 0.015% or less, preferably about 0.010% or less. The particular level of titratable peel oil in these feed juices often depends on the fruit from which it is derived. Generally, feed juices from non-Valencia fruit can be more easily processed to have lower levels of titratable peel oil than those obtained from Valencia fruit. For non-Valencia feed juices, the level of titratable peel oil typically ranges from about 0.004 to about 0.010%. For Valencia juices, the level of titratable peel oil typically ranges from about 0.006 to about 0.015%. By comparison, current commercial feed juices typically have titratable peel oil contents of from about 0.020 to about 0.045%. (The method for measuring the titratable peel oil content of feed juices of the present invention is described hereafter in part E of this application.) The level of peel oil present in the feed juice can greatly affect its orange aroma and flavor composition, as well as that of the resulting orange juice product. The orange flavor compounds present in peel oil tend to be bitter or burning in character. During subsequent stripping of the feed juice to remove and recover orange aroma and flavor volatiles prior to evaporative concentration, these bitter/burning flavor compounds can be removed and recovered as well. Since the stripped volatiles are subsequently added back to the concentrated juice, this can result in undesirable bitter/burning flavor characteristics in the orange juice product if the level of peel oil in the feed juice is too high. In addition, peel oil comprises predominantly terpene (or terpene-like) compounds which can be oxidized or thermally degraded to less desirable orange flavor compounds. High levels of peel oil can also adversely affect the partitioning of desirable water-soluble orange flavor compounds into the oil phase. The importance of minimized peel oil content on the orange aroma and flavor quality of feed juices is particularly shown by a ratio based on the level of more desirable orange compounds, relative to the level of less desirable orange compounds. For the purposes of the feed juices of the present invention, the level of more desirable orange compounds is based on the combined amount of acetaldehyde, methanol, ethyl butyrate, ethyl 3-hydroxyhexanoate and valencene. Acetaldehyde, methanol, ethyl butyrate and ethyl 3-hydroxyhexanoate are highly volatile compounds which contribute to the "freshness" of the feed juice. Valencene is a less volatile compound which contributes desirable "orangey" flavor character to the feed juice. For the purposes of the feed juices of the present invention, the level of less desirable orange compounds is based on the combined amount of hexanal, alpha -pinene, myrcene, decanal, linalool, and octanal. These less desirable compounds represent components obtained from the peel portion of the fruit, as well as undesirable degradation products. Except for hexanal, these compounds are generally less volatile than water. In addition to fruit variety (non-Valencia versus Valencia fruit) and juice processing conditions, seasonal and yearly variations in fruit lots can affect the ratio of more desirable to less desirable orange compounds for a given feed juice. Even so, it has been found, on average, that feed juices of the present invention have a higher ratio of more desirable orange compounds to less desirable orange compounds when compared to current commercial feed juices for a given variety of fruit. Conversely, it has also been found that this ratio, on average, is lower than that of hand-squeezed juice for a given variety of fruit. In addition, it has been surprisingly found that, as the level of titratable peel oil in feed juices of the present invention is decreased (e.g., from 0.015% to 0.010%), the change in chemical composition (especially the ratio of more to less desirable compounds) is far greater than would be expected from the decreased peel oil level. The differences in the ratio of more to less desirable compounds (averaged over two fruit seasons ± standard deviation) between feed juices of the present invention containing moderate titratable peel oil levels (Moderate Oil) and preferred low titratable peel oil levels (Low Oil), and hand-squeezed juice (HSJ) and current commercial feed juices (Current), are particularly shown in the following Tables: Florida Valencia Fruit HSJ Low Oil Moderate Oil Current Peel Oil(%) 0.0044 ±.0014 (n=66) 0.0106 ±.0013 (n=116) 0.0137 ±.0010 (n=36) 0.0332 ±.0065 (n=45) Ratio 49.10 ±19.72 (n=67) 18.48 ±7.68 (n=116) 12.63 ±4.70 (n=36) 5.44 ±2.13 (n=45) Certain Valencia feed juices of the present invention with ratios of more desirable to less desirable orange compounds of from about 8.5 to about 21.5 have been found to be especially preferred. These preferred Valencia feed juices have been found, in flavor paneling of the completely finished juice, to be equally preferred to certain hand-squeezed Valencia juice with ratios of from about 18 to about 52. These preferred Valencia feed juices have also been found, in flavor paneling of the completely finished juice, generally to be significantly preferred over current commercial Valencia feed juices with ratios of from about 3 to about 7. (It is also expected that non-Valencia feed juices of the present invention with ratios of more desirable to less desirable orange compounds of from about 8.5 to about 21.5 would provide similar results.) (The method used to measure the level of ethanol, methanol, acetaldehyde, ethyl butyrate and hexanal in feed juices of the present invention is the purge and trap analytical method described hereafter in part B of this application. The method used to measure the level of the remaining orange compounds in feed juices of the present invention is the tissue homogenization analytical method described hereafter in part B of this application.) Another important characteristic of the feed juices of the present invention is their level of flavanoid glycosides. The most predominant example of these glycosides is hesperidin. Hesperidin is present at significant levels in both the rag and the albedo portion of the peel, and at especially high levels in the pulp. Accordingly, the level of flavanoid glycosides present in the feed juice can be an indicator of how gentle was the extraction of the orange fruit and the finishing of the resulting juice. Generally, the more gentle the extraction and finishing, the lower will be the level of flavanoid glycosides in the feed juice. In addition to indicating the gentleness of extraction and finishing, the level of these flavanoid glycosides can affect the viscosity of the feed juice. Generally, the lower the level of these glycosides, the lower will be the viscosity of the feed juice (i.e., tends to parallel level of sinking pulp). Besides affecting the viscosity of the feed juice (and resulting orange juice product), high levels of these glycosides can cause fouling of evaporators used in the subsequent concentration step, leading to development of cooked off-flavor. For feed juices of the present invention, it is desirable to minimize the level of flavanoid glycosides. The particular level of glycosides in these feed juices depends on the fruit from which it is derived. Generally, feed juices obtained from non-Valencia fruit have higher levels of glycosides than those obtained from Valencia fruit. For non-Valencia feed juices, the level of these glycosides is about 200 mg. or less per 100 ml., with a typical range of from about 125 to about 200 mg. per 100 ml. For Valencia feed juices, the level of these glycosides is about 175 mg. or less per 100 ml., with a typical range of from about 100 to about 175 mg. per 100 ml. (The method for measuring the level of flavanoid glycosides in feed juices of the present invention is described hereafter in part B of this application.) The unique feed juices of the present invention are obtained by a combination of careful fruit selection and processing conditions. The first step is to select processable orange fruit. As used herein, the term "processable orange fruit" refers to fruit which can be processed with commercial juice extraction and finishing equipment to provide feed juices having a ratio of Brix solids to titratable acidity (TA) of from about 12 to about 20, preferably from about 14 to about 18. For example, soft, rotten or immature fruit are preferably removed to prevent the introduction of undesired contaminants into the feed juice. In addition, the selected fruit is preferably processed into feed juice within about 48 hours of being harvested. This minimizes the development of off-flavor compounds in the fruit which occurs over time, especially as the result of abuse and damage during storage. The selected fruit is gently extracted in a commercial juice extractor to provide extracted juice having about 0.015% or less titratable peel oil, preferably about 0.010% or less titratable peel oil. The term "gently extracted" refers to an extraction method which minimizes the level of peel oil in the extracted juice. Gentle extraction methods also minimize the abrasion of rag and albedo portions of the peel which contain flavanoid glycosides. Further, gentle extraction methods typically avoid significant shredding and cutting of the juice sacs which can add significant levels of sinking pulp to the extracted juice. The term "commercial juice extractor" refers to a mechanical juice extractor which is capable of processing at least 200 orange fruit per minute. There are three general types of commercial juice extractors. One is referred to as a "reamer-type" juice extractor. In reamer-type juice extractors, fruit entering the machine is sliced in half. The two halves go to opposite sides of the machine. The halves are oriented, picked up by cups, and then positioned across serrated reamers revolving on a synchronized carrier, on a slightly inclined plane. As the fruit progresses around the extractor turntable, the inclined plane causes the rotating reamers to exert increasing pressure on the halved fruit and thus express the juice. See Nagy et al, Citrus Science and Technology , Vol. 2, (1977), pp. 192-93. Examples of suitable reamer-type juice extractors include the Brown Model 400 (up to 350 fruit per minute), the Brown Model 700 (up to 700 fruit per minute), and the Bertuzzi Model R-16 (up to 400 fruit per minute). See also U.S. Patent 3,858,500 to Rohm et al, issued January 7, 1975, and U.S. Patent 4,421,021 to Holbrook, issued December 20, 1983, for other examples of reamer-type juice extractors. The second type of juice extractor used in the citrus industry is referred to as a "rotating disc-type." In a rotating disc-type juice extractor, each fruit becomes wedged between pairs of revolving, tapered, circular rubber discs. The discs carry the fruit through a steel knife which slices the fruit in half. Each half travels a converging path between a perforated steel grid and one of the rotating discs, thus causing juice to be extracted. (The grid provides a coarse primary finishing of the juice simultaneous with extraction.) The extracted juice flows to the bottom of a collector where it can be divided into a low peel oil/pulp fraction from the earlier, lighter pressure stage of extraction and a high peel oil/pulp fraction from the later, greater pressure stage of extraction. See Nagy et al, supra , pp. 194-95. Suitable rotating disc-type juice extractors include the Brown Model 1100. See also U.S. Patent 3,245,339 to Leslie et al. issued April 12, 1966, and U.S. Patent 4,170,935 to Rohm et al, issued October 16, 1979, for other examples of rotating disc-type extractors. The third type of juice extractor used in the citrus industry is referred to as a "reciprocating cup-type." In a reciprocating cup-type extractor, each fruit is deposited in a lower cup. The upper cup then descends which causes the sharp upper end of a round steel tube to cut a circular hole in the bottom of the fruit. As the plurality of fingers of the upper and lower cups mesh, the expressed juice-laden segments pass into the tube through the hole cut in the fruit. The lower end of the tube has a restrictor to prevent the loss of juice and to force the juice through perforations in the side of the tube. Seeds, rag, peel and large pulp particles remain inside the tube. See Nagy et al, supra , pp. 190-191. Examples of suitable reciprocating cup-type juice extractors include the FMC Model 291, the FMC Model 391, the FMC Model 491 and the FMC Model Low Oil Juice machines. See also U. S. Patent 4,376,409 to Belk, issued March 15, 1983, and U.S. Patent 4,309,943 to Larson et al, issued January 12, 1982, for other examples of reciprocating cup-type juice extractors. Unless the orange fruit has been de-oiled, most reamer-type, rotating disc-type and reciprocating cup-type juice extractors will provide extracted juice having a titratable peel oil content above about 0.015% for Valencia fruit and typically above about 0.010% for non-Valencia fruit. Accordingly, a preferred step prior to juice extraction is to de-oil fruit. De-oiling of fruit can be achieved by using a scarifier device. Scarifiers work by pricking the surface of the orange fruit. This permits peel oil to exude out of the fruit. The exuded peel oil can be washed off of the fruit and removed to prevent its inclusion in the extracted juice. Suitable scarifiers for carrying out this de-oiling step include Brown Oil Extractors, Indelicato Scarifiers or Bertuzzi Citro Raps. Not all juice extractors require a prior de-oiling operation in order to provide extracted juice having the previously specified maximum peel oil contents. One such juice extractor is the Model Low Oil Juice machine manufactured by FMC Corporation, Citrus Machinery Division, of Lakeland, Florida. The FMC Low Oil Juice machine is a reciprocating cut-type juice extractor which is capable of providing extracted juice having titratable peel oil contents of about 0.015% or less for Valencia fruit (typically about 0.010% or less for non-Valencia fruit) without a prior de-oiling step. Extracted juice having titratable peel oil contents as low as 0.006% can be obtained from Valencia fruit (as low as 0.004% when obtained from non-Valencia fruit) using this Low Oil Juice machine. Accordingly, a prior de-oiling step is optional with such Low Oil Juice extractors. The extracted juice is partially finished by removing non-juice materials. As used herein, the term "non-juice materials" refers to any rag, seed or peel materials present in the extracted juice. These non-juice materials, which are relatively large in size, are essentially the waste product of juice extraction. More importantly, these non-juice materials contain undesirable bitter flavor compounds and enzymes (e.g., pectinesterase) which can be leached out by the extracted juice. Accordingly, these non-juice materials need to be removed gently and quickly from the extracted juice. By "gently" is meant removal such that there is minimal expression of the bitter flavor compounds and enzymes from the nonjuice materials into the extracted juice, as well as minimal grinding of nonjuice materials. Gentle removal methods typically impart relatively low work-energy input to the extracted juice. By "quickly" is meant removal of these non-juice materials before excessive amounts of undesirable bitter flavor components and enzymes can be leached out by the extracted juice. Generally, removal of these non-juice materials within about 3 minutes of juice extraction is sufficient to avoid excessive leaching out of bitter flavor compounds and enzymes. When a reamer-type or rotating disc-type juice extractor is used, partial finishing of the extracted juice requires the use of a primary finisher. Liquatex vibrating screens are particularly suitable primary finishers. In operation, the extracted juice is poured onto the screen of the finisher. The mesh size of the screen is such that the partially finished juice passes through the screen while non-juice materials are retained on the top thereof. This screen is gently vibrated to cause the non-juice materials to move to one side of the screen so that they can be removed. Vibration of the screen is such that a relatively low work-energy input is imparted to the juice, i.e. less than 1.39 kJ/ℓ (5 BTU per gallon) of extracted juice, preferably less than 0.56 kJ/ℓ (2 BTU per gallon) of extracted juice. This low-energy work input prevents or minimizes expression of bitter flavor compounds and enzymes from non-juice materials. Other primary finisher devices, such as rotating screens, which impart low-work energy input to the extracted juice can also be used instead of a vibrating screen. Although vibrating screen primary finishers gently and quickly remove non-juice materials from the extracted juice, they also reduce the effective yield of juice from the orange fruit. The low-work energy input required for gentle removal of non-juice materials results in fairly large amounts of desirable juice being entrained in the non-juice material stream. This entrained juice is usually difficult or impossible to recover from the non-juice materials. Accordingly, for increased juice yield, it is preferred to use reciprocating cup-type juice extractors. Reciprocating cup-type juice extractors do not require a primary finisher since juice extraction and removal of non-juice materials are carried out at the same time in about 1 second or less. This combined extraction/finishing operation prevents the entrainment of juice in the non-juice materials. After non-juice materials have been removed, sensible pulp is then removed from the partially finished juice to provide a completely finished juice. As used herein, "sensible pulp" refers to insoluble pulp particles which have a size greater than about 0.5 mm. Sensible pulp can be removed from the partially finished juice by any suitable screw-type or paddle-type juice finisher, or by a vibrating screen. Examples of suitable screw-type finishers include Brown Model 2503 and 3600 screw finishers, FMC Model 35 screw finisher, and preferably FMC Model UCF 200 "close tolerance" finishers. Examples of suitable paddle-type finishers include the Brown Model 200 paddle finisher. See Nagy et al, supra , at pp. 196-99 As can be gathered from its name, sensible pulp imparts mouthfeel properties to orange juice and is, therefore, a desirable component of orange juice products. However, in order to properly process the feed juice, sensible pulp must be removed for at least two reasons. The first is to prevent absorption by the pulp of desirable orange aroma and flavor compounds. Once absorbed, these compounds cannot be easily removed during subsequent volatile stripping of the feed juice and represent an essence yield loss. In addition, sensible pulp needs to be removed for efficient evaporative concentration. Because of its size, any sensible pulp present in the feed juice can: (1) build up and plug equipment used in evaporative concentration, thus necessitating repeated cleaning operations to remove it; and (2) affect the feed juice flow pattern through the evaporators, thus lowering the juice solids content of the resulting concentrate or causing scorching of the juice solids. Accordingly, the completely finished juice needs to be substantially free of sensible pulp. As used herein, "substantially free of sensible pulp" refers to a sensible pulp level of less than about 1% in the completely finished juice. Typically, the level of sensible pulp in the completely finished juice is as close to 0% as possible. A screw-type or paddle-type finisher fitted with a 20 mesh screen will typically remove all (or almost all) of the sensible pulp. Once removed, the sensible pulp is typically processed further (e.g. pasteurized) and stored for subsequent inclusion in the final orange juice products. After removal of the sensible pulp, the completely finished juice has a sinking pulp level of at least about 10%. Typically, the sinking pulp level of the completely finished juice is from about 12 to about 30%. The viscosity of this completely finished juice is at least about 10 mPas (10 centipoise), and is typically from about 12 to about 30 mPas (12 to about 30 centipoise). This viscosity needs to be somewhat lower for efficient evaporative concentration of the feed juice, as well as to provide orange juice products having a texture/mouthfeel which more closely approaches hand-squeezed orange juice. To lower the viscosity of the completely finished juice, at least some of the sinking pulp is removed. The amount of sinking pulp removed is such that the resulting feed juice has sinking pulp level of about 8% or less (typical range of from about 5 to about 8%) for non-Valencia fruit and about 10% or less (typical range of from about 7 to about 10%) for Valencia fruit. This is also results in the feed juice having a viscosity of about 8 mPas (8 centipoise) or less (typical range of from about 5 to about 8 mPas (about 5 to about 8 centipoise)) for non-Valencia fruit and about 10 mPas (10 centipoise) or less (typical range of from about 7 to about 10 mPas (about 7 to about 10 centipoise)) for Valencia fruit. Removal of sinking pulp from the completely finished juice is typically achieved by using centrifugation. However, other separation methods involving filters, juice finishers, belt presses and stationary screens can also be used to remove a portion of the sinking pulp from the completely finished juice to provide the feed juices of the present invention. Surprisingly, the high quality feed juices of the present invention can be obtained at commercially useful juice yields. This is particularly true if reciprocating cup-type juice extractors are used. When such extractors are used, the feed juice of the present invention can be obtained at juice yields of at least about 90%. In particular, juice yields of from about 92 to about 95% are achievable when the FMC Low Oil Juice machine is used. (Under the definition below, it is possible to have juice yields in excess of 100%.) For the method of the present invention, "juice yield" is based on the total amount of juice solids obtained per box of orange fruit (processed juice solids yield), relative to the amount of juice solids obtained per box of orange fruit by using a "state test" juice extractor ("state" juice solids yield) as specified in Florida regulation 20-63.001. In other words, the juice yield can be obtained by the following equation: % juice yield = 100% x (processed juice solids yield)/("state" juice solids yield) where processed juice solids yield = juice yield (per box) from process x solids content (°Brix) of juice, and where "state" juice solids yield = juice yield (per box) from "state test" extractor x solids content (°Brix) of juice. Reciprocating cup-type juice extractors are also desirable in terms of increasing the yield of sensible pulp compared to reamer-type and rotating disc-type extractors. The primary finisher required to remove non-juice materials when a reamer-type or rotating disc-type juice extractor is used diminishes not only the juice yield but also the yield of sensible pulp. Accordingly, use of reciprocating cup-type extractors to obtain feed juices of the present invention provides an optimum combination of juice yield and sensible pulp yield. The feed juices of the present invention are particularly useful in the aroma/flavor volatile stripping and evaporative concentration processes. However, these feed juices are also suitable for freeze concentration processes because of their relatively low viscosity and titratable peel oil content, and good orange aroma/flavor character. See U. S. Pat. 4,374,865 to Strobel, issued February 22, 1983, for a suitable freeze concentration process. The following are representative examples of feed juices obtained according to the present invention. Example 1 Florida Pineapple orange fruit having a diameter of 73 mm (2-7/8 inches) or less were thoroughly washed prior to juice extraction. The washed fruit was extracted by using an FMC Model Low Oil juice machine. Sensible pulp was removed from the extracted juice by passing it through an FMC Model 35 screw finisher having a 20 mesh screen (i.e. 0.5 mm (0.020 in.) openings) and a pressure setting of 1.38 bar (gauge) (20 psig). The resulting completely finished juice had the following physical and chemical characteristics: This completely finished juice can be passed through a desludger centrifuge operated at 1000 to 3000 g force to remove additional sinking pulp so as to provide a feed juice having a viscosity of about (8 mPas) 8 centipoise or less and a sinking pulp level of about 8% or less. Example 2 California Valencia orange fruit was randomized with decayed fruit being removed prior to deoiling. A Bertuzzi Citrorap CI 33/6 deoiler was set up with approximately 29-32°C (85°-90°F) rinse water sprays, rasping rolls at a maximum speed of 300 rpm, and a feed auger speed of 8 rpm. An FMC Model 291 juice extractor (500 fruit processed per minute) was also used with the following machine settings: Cups 76 mm. (3 inch) standard Peel clearance 4 mm. (10/64 inch) Restrictor 11.1 mm. (7/16 inch) long bore Strainer tube 1 mm. (0.040 inch) Orifice tube 25 mm. (1 inch) Beam setting 19 mm. (3/4 inch) Two and one-half boxes of the washed oranges were dumped slowly into the deoiler and then collected in a strainer basket. A portion of these deoiled oranges were used to prime the extractor, with the extracted juice being discarded. An additional 27 kg. (60 lbs.) of deoiled fruit was then extracted. This extracted juice had a titratable peel oil content of 0.013%. This juice can be passed through a Model 35 screw finisher having a 20 mesh screen and a pressure setting of 1.38 bar(gauge) (20 psig) to provide a completely finished juice. This completely finished juice can then be passed through a desludger centrifuge operated at 1000 to 3000 g force to remove additional sinking pulp so as to provide a feed juice having a viscosity of about 10 mPas (10 centipoise) or less and a sinking pulp level of about 10% or less. Example 3 Florida Valencia orange fruit having a diameter of 73 mm. (2-7/8 inches) or less were throughly washed prior to juice extraction. The juice was extracted using an FMC Model Low Oil juice machine. The extracted juice was passed through an FMC UCF 200 finisher having a 20 mesh screen at a pressure setting of 1.38 bar(gauge) (20 psig). The resulting completely finished juice had the following physical and chemical characteristic: This completely finished juice can be passed through a desludger centrifuge operated at 1000 to 3000 g force to remove additional sinking pulp so as to provide a feed juice having a viscosity of about 10 mPas (10 centipoise) or less and a sinking pulp level of about 10% or less. Example 4 Process grade Hamlin orange fruit which had been stored for approximately 24 hours prior to extraction was used. Several bins of fruit were blended to achieve a nominal 15 Brix/Acid ratio average. The blended fruit was washed with CS-100 at 100 ppm followed by a fresh water rinse. The cleaned fruit was visually inspected and graded immediately prior to extraction. After grading, the fruit exhibited less than 2% decay and 10% unwholesome defects. The fruit was split into two size ranges. Small fruit (less than 75 mm (3 inches) in diameter) was fed to a first set of FMC Low Oil Juice extractors. Large fruit (greater than 75 mm (3 inches)) was fed to a second set of FMC Low Oil Juice extractors. Extracted juice, containing sensible pulp and seed defects, was collected in an enclosed manifold and surged into a feed tank. This juice was then pumped through hydro-clone deseeders operating at a nominal 5.2 bar(gauge) (75 psig) back pressure to remove immature seed defects. The juice then was passed through a FMC UCF 200 finisher, operating with a 0.5 mm (0.020 inch) screen and 0.35 bar(gauge) (5 psig) back pressure, to remove sensible pulp. The pulp-free juice was surged into a level controlled tank prior to centrifugation. Westfalia SB-80 desludger centrifuges, operating at 3000 g force, removed sinking pulp from the juice stream. Feed rate and shot cycle times were adjusted to achieve desired viscosity reduction in the feed juice. This feed juice was compared to hand-squeezed juice prepared from identical oranges which had been cut in half, reamed gently on an Oster juicer and hand sieved through a 20 mesh screen. Analytical results of this comparison are shown below: Hand-Squeezed Juice Feed Juice of Present Invention Brix° 10.23 10.63 Titratable Acidity (%) 0.68 0.69 Brix/Acid Ratio 15.0 15.4 Oil (%) 0.0028 0.0052 Sinking Pulp (%) 13 6 Viscosity (cps) (mPas) 9.0 5.2 Ratio of More to Less Desirable Compounds 57.67 23.15 B. Analytical Methods 1. Feed juice and orange juice products a. Purge and trap headspace analysis The purge and trap headspace analytical system consists of a Hewlett-Packard (HP) 7675A purge and trap sampler and a HP 5880A gas chromatograph (G.C.). This analytical system is modified for automatic operation. Sample introduction to a capillary column is achieved by adding a four port valve to the 7675A sampler and a cold trap to the column oven of the 5880A G.C. A 1 ml. sample of juice is placed into a sampling container (15 ml. volume culture tube) equipped with a Teflon®-coated stirring bar. After equilibration in a water bath (27 ± 1°C) for 5 minutes with magnetic stirring, the volatile compounds are swept into a room temperature adsorption tube, by helium at a rate of 10 ml./min. for 1 minute. The adsorption tube is filled with 200 mg. of Tenax® (80/100 mesh) adsorbent (Applied Science Division of Milton Roy Co.) and a small plug of silylated glass wool at each end to keep the adsorbent in place. This hydrophobic polymer selectively adsorbs the organic volatiles and the helium stream containing water is vented to atmosphere. The Tenax® tube is then flushed one more minute with clean, dry helium gas (10 ml./min., flow rate) to remove water from the trap. (This water can cause clogging problems by ice formation in the cold trapping system of the capillary column.) Sample injection into a capillary column is performed via desorption of the Tenax® trap and reconcentration of the desorbed sample onto the first portion (51 mm.) (2 inches) of the capillary column. Thermal desorption is effected by rapidly heating the Tenax® tube to 200°C for 8 minutes with helium flowing through it at a flow rate of 2.7 ml./min. The front portion of the capillary column is located inside a trap cooled with liquid nitrogen (-150°C). The sample is swept from the Tenax® tube onto the capillary column where it condenses out in a narrow hand at liquid nitrogen temperatures. For injection of the sample into the capillary column, after cooling, this cold trap is heated very rapidly: it takes about 20 seconds to reach 140°C and the temperature is held at 140°C for 1 minute. The helium switching valves and the cooling and heating sequences of the cold trap are controlled automatically in a pre-programmed mode. The capillary column used is a Durawax-3 fused silica capillary column (J&W Scientific, Inc., 0.32 mm. i.d x 60 m. length). Durawax-3 is a stabilized liquid phase which contains 50% of Carbowax-20M and 50% of methyl silicone. The carrier gas flow (He) at the capillary column outlet is 2.7 ml./min. (linear gas velocity = 34.5 cm./sec. at 40°C). The injection port and flame ionization detector temperatures are set at 180°C and 220°C, respectively. The column oven temperature is held at 50°C for 18 minutes, raised to 70°C at 1.5°C/min., then raised at 5°C/min. to 145°C and then held at 145°C for 8 minutes. The compounds are identified by the retention times of peaks obtained for known standards and mass spectrometry. The purge and trap headspace analytical system was connected directly to a Finnigan Mat 4500 mass spectrometer using a Super INCOS data system. Integration of peak area is obtained by use of a Hewlett-Packard 5880A series terminal, level four, or a Hewlett-Packard 3357E Laboratory Automation System. This automated headspace analytical system provides good precision for most of the aroma compounds (percent relative standard deviation = 5.0 - 14.7%, n = 6). Juice samples are analyzed at single strength, i.e., at 11.8° Brix. In order to quantitate the concentration of the five identified components (acetaldehyde, methanol, ethanol, ethyl butyrate and hexanal) in the orange juice, a linear regression analysis is performed using standard addition of individual components into orange juice stripped of its volatile components. Five different concentration ranges with duplicated analytical data are used to construct the linear regression equation shown in Table 1. Y represents peak area of the individual components on the chromatogram. The concentration of the components in the orange juice (ppm) is expressed as X (ppm can be converted to ppb by multiplying it by 1000). From these equations, the concentration of the five components in the orange juice is calculated from the peak area on the headspace chromatogram obtained under the same analytical condition. b. Tissue Homogenization Method The tissue homogenization (TH) method is based on a direct extraction of the orange juice flavor components with a solvent, methylene chloride. After homogenization, the solvent layer is separated and evaporated to a small volume. Quantitation is done using an internal standard. A calibration standard is prepared as indicated below: An internal standard solution is prepared by adding 10 microl. of propyl benzene to 40 ml of ethyl acetate. For calibration, 200 microl. of the calibration standard mixture is spiked into orange juice concentrate stripped of its volatile components. This calibration sample is diluted to 11.8° Brix before use. The analytical procedure is as follows: weigh 30 g of orange juice (11.8° Brix) into a 100 ml mass cylinder. The internal standard solution (50 microl.), methylene chloride (8 ml) and saturated salt solution (3 ml) are added to the orange juice sample. The sample is then homogenized for 30 seconds. The homogenized sample is transferred to a centrifuge tube and centrifuged at 10,000 rpms at 5°C for 30 minutes. The bottom solvent layer is transferred to a 5 ml vial and evaporated to a small volume under nitrogen. A Hewlett-Packard 5880A gas chromatograph equipped with a capillary column injector is used in the analysis. A Hewlett-Packard 3357 minicomputer with basic program is used to obtain data from the gas chromatograph. The following conditions are used: Air flow rate 300 ml./min. Hydrogen flow rate 30 ml./min. Nitrogen flow rate 30 ml./min. (make up gas) Helium flow rate 3 ml./min. (carrier gas) (20 psi setting) Split flow 20 ml./min. Septum purge flow 2-3 ml./min. A DX-4 fused silica capillary column (0.32 mm. x 60 m., J&W Scientific) is used for analysis. The oven is heated at 50°C for 5 minutes and then programmed to rise 2°C/min. to a temperature of 120°C. The oven temperature then rises at 1.5°C/min. to a temperature of 160°C, then rises 8°C/min. to a temperature of 210°C, then rises at 3°C/min. to a temperature of 240°C, and is then held at 240°C for 10 minutes. The methylene chloride extract of the calibration sample is injected into the gas chromtograph to establish the retention time and response factor for each component. The response factor of the calibration extract is corrected for any residual levels present in the stripped orange juice concentrate, as previously determined. The identity of each compound in the chromatogram is confirmed using retention time data of a known standard, as determined by a Finnigan MAT 4500 GC mass spectrometer. A Hewlett-Packard 3357 minicomputer is used to obtain data from the gas chromatograph. The amount of each compound in the juice sample (mg./ml. or ppb) is calculated as follows: c. Flavanoid glycoside analysis A stock solution containing 240 mg. of hesperidin per 100 ml. is prepared by dissolving 300 mg. of 80% pure hesperidin in a 100 ml. volumetric flask containing 80 ml. of 0.1 N NaOH, adjusting the pH to 7.0 with glacial acetic acid, and then diluting to volume with distilled water. From this stock solution, standard solutions containing 40, 80, 120 and 180 mg. of hesperidin per 100 ml. are also prepared. The stock solution and the 4 standard solutions are used to obtain a standard spectrophotometric curve as follows: For each solution, 3 test tubes are used (15 in all). Into each test tube is pipetted 5 ml. of diethyleneglycol (90% concentration) and 0.1 ml. of the standard solution. After each test tube is mixed well with a Vortex mixer, 0.1 ml. of 4 N NaOH is added to the second and third test tubes, followed by mixing with a Vortex mixer. The test tubes are allowed to stand for 45 minutes for full development of yellow color before spectrophotometric measurements are taken. The first test tube containing only standard solution and diethyleneglycol is used to zero the spectrophotometer (Bausch & Lomb Spec. 21) at 420 nanom. for the second and third test tubes. The readings for the second and third test tubes are averaged to obtain the absorbency value for each standard solution. The absorbency values for the stock and standard solutions are plotted to provide a standard curve from which absorbency values can be converted into mg. of hesperidin per 100 ml. Juice samples analyzed for flavanoid glycosides should be free of sensible pulp, i.e. pulp which does not pass through a 20 mesh screen. The absorbency value for each juice sample is determined by the same procedure used to determine absorbency values for the stock and standard solutions. The absorbency value for the juice sample is then compared with the standard curve to determine the mg. of hesperidin in the sample per 100 ml. d. Viscosity Into the sample cup of a UL-adapator is poured 16 ml. of a viscosity standard (known viscosity of 5 to 10 mPas (5 to 10 centipoise)). A Brookfield LVTD rotational viscometer is set up with the UL-adaptor being placed in a 25°C waterbath. The viscosity standard in the sample cup is allowed to equilibrate in the waterbath for 10 minutes before a reading is taken at 12 rpm. The known viscosity of the viscosity standard is divided by the average dial reading at 12 rpm to determine the response factor. Sensible pulp is removed from the juice sample (solids content of 11.8° Brix) by passing it through a 20 mesh screen. (For concentrate products, water is added to dilute the juice sample to 11.8° Brix prior to pulp removal.) Into the sample cup of the UL-adaptor is poured 16 ml. of the screened sample. The UL-adaptor of the viscometer is placed in an 8°C waterbath. The screened juice sample is allowed to equilibrate in the waterbath for 15 minutes before a reading is taken at 12 rpm. The viscosity of the juice sample at 12 rpm is determined by multiplying the dial reading by the response factor. e. Volume % of sinking pulp The juice is stirred enough to obtain a uniform sample. Sensible pulp is removed from the sample by passing it through a 20 mesh screen. (For concentrate products, water is added to dilute the juice sample to 11.8° Brix prior to sensible pulp removal.) The screened sample is equilibrated to a temperature of 26.7 ± 1.1°C (80 ± 2°F). Two conical 50 ml. graduated tubes are then filled with exactly 50 ml. each of the well mixed, equilibrated sample. The tubes are placed in the centrifuge (IEC Model HN-SII, IEC Centrifuge Head #215, IEC Trunnion rings #325, IEC Shields #320) so that the graduated scale faces the direction of rotation. With the load balanced, the samples are centrifuged at 1500 rpm for 10 minutes. The mls. of pulp at the bottom of each tube is read to the nearest ml. and then multiplied by 2 to get the volume % of sinking pulp. The values for the tubes are averaged to obtain the volume % of sinking pulp for sample. f. Titratable peel oil content (Scott Oil Method) This method is based on the Scott Oil Method described in Nagy et al, Citrus Science and Technology, Vol. 2 (1977), pp. 506-508. In this method, peel oil is distilled from an 2-propanol solution of the juice sample and then titrated with a standard KBr-KBr0₃ solution in an acidic medium. A 0.025 N KBr-KBr0₃ titrant solution is prepared by diluting 1 part of a 0.1 N KBr-KBr0₃ solution (from RICCA Chemical Company, Arlington, Texas, Catalog No. 1170), with 3 parts distilled water. An acidic indicator solution is also prepared by mixing together 5 ml. of a 0.1% methyl orange solution with 1000 ml. of a dilute hydrochloric acid solution ( 2 parts distilled H₂O, 1 part HCl). A standard Scott Peel Oil Distillation Apparatus is used in this method. This apparatus essentially consists of a flat bottom distillation flask, an inclined adaptor and a distillation condenser. A blank titration value (TB) is obtained by titrating 3 separate mixtures containing 25 ml. of 2-propanol and 10 ml. of the acidic indicator solution with the titrant solution and then dividing the total ml. of titrant solution used by 3. For single-strength products and feed juices, 25 ml. of a well mixed juice sample is pipetted into the distillation flask containing boiling chips or beads, followed by the addition of 25 ml. of 2-propanol. The mixture in the distillation flask is then heated to a temperature of about 85°C. Distillate is collected until condensation of water vapor appears on the transfer tube (approximately 35 ml. of distillate). The the distillate is then added 10 ml. of the acidic indicator solution. While being stirred with a magnetic stirrer, the acidic distillate solution is titrated with titrant solution to a colorless endpoint. The volume of titrant solution required to reach the endpoint (TS) is recorded. The % titratable peel oil for the sample is then obtained by the following calculation: % titratable peel oil = (TS-TB) x 0.004 For concentrate products, water is added until the sample is diluted to 11.8° Brix. The titratable peel oil content of this diluted sample is then determined by the same method used for single strength products and feed juices. 2. Aqueous stripper essence a. Capillary column gas chromatographic analysis of volatiles other than ethanol, methanol and acetaldehyde. A standard mixture solution is prepared by adding absolute ethanol (10 ml.) to a 50 ml. volumetric flask, followed by various compounds present in orange juice in the amounts indicated below: After all of the above compounds are added to the flask, the standard mixture solution is diluted to volume with ethanol. An internal standard solution is also prepared by adding a small volume (2-3 ml.) of distilled water to a 10 ml. volumetric flask. Cyclohexanone (25 microl.) is added and the water/cyclohexanone internal standard solution is diluted to volume with distilled water. A calibration solution is prepared by pipetting 4 ml. of a 15% ethanol solution into a 2 dram vial which is then spiked with 20 microl. of the internal standard solution and 20 microl. of the standard mixture solution. A sample solution is prepared by first rinsing the pipette with a portion of the sample twice, pipetting 4 ml. of the sample into a 2 dram vial and then spiking the vial with 20 microl. of the internal standard solution. A Hewlett-Packard 5880A Gas Chromatograph equipped with a capillary column injector is used in the analysis. A Hewlett-Packard 3357 minicomputer with basic program is used to obtain data from the gas chromatograph. The following conditions are used: Air flow rate 250 ml./min. Hydrogen flow rate 30 ml./min. Nitrogen flow rate 30 ml./min. (make up gas) Helium flow rate 2 ml./min. (carrier gas) (0.65 bar (9.5 psi) setting) Split flow 10 ml./min. Septum purge flow 3 ml./min. A DB-1 fused silica capillary column (0.32 mm. x 30 m., J&W Scientific) is used with the gas chromatograph. The oven is heated at 40°C for 7 minutes and then programmed to rise 3.0°C/min. to a temperature of 80°C. The oven temperature then rises at 5°C/min. to a final temperature of 240°C, and is then held at 240°C for 5 minutes. A 1 microl. portion of the calibration solution is injected into the gas chromatograph to establish the retention time and response factor for the various compounds present. A 1 microl. portion of the sample solution is injected into the gas chromatograph and then compared against the calibration solution gas chromatograph to identify the various compounds. The amount of each compound in the sample solution (mg./ml. or ppm) is calculated as follows: b. Packed column gas chromatographic analysis of ethanol, methanol and acetaldehyde. An internal standard solution is prepared by adding n-propanol (0.2 ml.) to a 250 ml. volumetric flask, and then diluting to volume with distilled water. An acetaldehyde stock solution is also prepared by adding 5 ml. of distilled water to a 25 ml. volumetric flask. Acetaldehyde (1 ml.) is added and the acetaldehyde stock solution is diluted to volume with distilled water. A calibration solution is prepared by adding 300 ml. of distilled water to a 500 ml. volumetric flask, followed by 10 ml. of ethanol, 1 ml. of methanol and 8 ml. of the stock acetaldehyde solution. This calibration solution is diluted to volume with distilled water. A calibration sample is prepared by pipetting 1 ml. of the calibration solution and 1 ml. of the internal standard solution into a 1 dram vial. A sample solution is prepared by pipetting 1 ml. of the sample and 1 ml. of the internal standard solution into a 1 dram vial. A Hewlett-Packard 5890 Gas Chromatograph equipped with a flame ionization detector is used in the analysis. A Hewlett-Packard 3390A integrator is used to obtain data from the gas chromatograph. The following conditions are used: Air flow rate 2.6 bar (38 psi) Hydrogen flow rate 0.8 bar (12 psi) Nitrogen flow rate 25 ml./min. A Carbopack B/5% 80/120 mesh packed column (2 mm. x 6 ft.) is used with the gas chromatograph. The oven is heated to 80°C for 2 minutes and then programmed to rise 8.0°C/min. to a temperature of 120°C. The injector temperature is 150°C while the detector temperature is 200°C. A 1 microl. portion of the calibration sample is injected into the gas chromatograph to establish the retention time and response factor for ethanol, methanol and acetaldehyde. A 1 microl, portion of the sample solution is injected into the gas chromatograph and then compared against the calibration sample gas chromatograph to identify the various compounds. The amount of each compound in the sample solution (mg./ml. or ppm) is calculated as follows: 3. Capillary column gas chromatographic analysis of stripper oil volatiles. A standard mixture is prepared by adding the following compounds present in orange oils in the amounts indicated below to a flask: An internal standard solution is also prepared by adding a small volume (10-20 ml.) of ethyl acetate to a 100 ml. volumetric flask. Propyl benzene (300 microl.) is added and then the internal standard solution is diluted to volume with ethyl acetate. A calibration solution is prepared by adding 1 ml. of the standard mixture solution and 1 ml. of the internal standard solution to a 1 dram vial. A sample solution is prepared by first rinsing the pipette with a portion of the sample twice, and then pipetting 1 ml. of the sample and 1 ml. of the internal standard solution into a 1 dram vial. A Hewlett-Package 5880A Gas Chromatograph equipped with a capillary column injector is used in the analysis. A Hewlett-Packard 3357 minicomputer with basic program is used to obtain data from the gas chromatograph. The following conditions are used: Air flow rate 250 ml./min. Hydrogen flow rate 30 ml./min. Nitrogen flow rate 30 ml./min. (make up gas) Helium flow rate 3 ml./min. (carrier gas) (1.38 bar(20 psi)setting) Split flow 150 ml./min. Septum purge flow 3 ml./min. A DX-4 fused silica capillary column (0.32 mm. x 60 m., J&W Scientific) is used with the gas chromatograph. The oven is heated at 55°C for 5 minutes and then programmed to rise 2°C/min. to a temperature of 120°C. The oven temperature then rises at 1.5°C/min. to a temperature of 160°C, then at 4°C/min. to a final temperature of 220°C, and is then held at 220°C for 10 minutes. A 1 microl. portion of the calibration solution is injected into the gas chromatograph to establish the retention time and response factor for the various compounds present. A 1 microl. portion of the sample solution is injected into the gas chromatograph (using solvent plug technique) and then compared against the calibration solution gas chromatograph to identify the various compounds. The amount of each compound in the sample solution is calculated as follows: 4. Evaporative orange juice concentrate a. Viscosity The viscosity of juice concentrates is determined by the same method as E(1)(d) for feed juices, but using a RVT Brookfield viscometer with a No. 6 or 7 spindle rotated at 100 rpm. b. Pectinesterase Activity This method determines the amount of activity of the enzyme pectin methylesterase (pectinesterase) in the juice or juice concentrate. A 2 M sodium chloride stock solution is prepared by placing 58.45 grams of sodium chloride in a 500 ml. volumetric flask, adding distiled water to the mark and then shaking until the sodium chloride is completely dissolved. A 1% pectin/salt solution is prepared as follows: a 75 ml. portion of the 2M sodium chloride stock solution is placed in a 1 liter volumetric flask which is then diluted to the mark with distilled water. The blender jar (Waring blender) is then filled approximately 3/4 full with this solution. Using a variable transformer, the blender is run at an approximately 40% setting. Pure citrus pectin (10 ± 0.1 g.) is slowly sifted into the blender jar, followed by the remaining 1/4 of the salt solution. This 1% pectin/salt solution is then blended for approximately 1 minute. Pectinesterase activity in the sample is determined as follows: a 100 ml. portion of the 1% pectin/salt solution is placed in a 250 ml. beaker which is brought to a temperature of 35°C ± 1°C by using a water bath. A 10 ml. juice concentrate sample diluted to 11.8° Brix is then pipetted into the solution in the beaker. A magnetic stirrer is placed in the solution, followed by insertion of pH meter electrodes (Fisher Titrimeter II Fep) and then the solution is stirred slowly. Enough 0.10 N NaOH solution is added to raise the pH of the solution to just barely over 7.5, e.g. 7.6. When the pH of the solution lowers to exactly 7.5, 0.02 N NaOH is added for 10 minutes at a rate that will hold the pH as near 7.5 as possible. The milliliters of 0.02 N NaOH required during this 10 minute period are used in the following calculation to determine pectinesterase activity (P.E. Units) of the juice concentrate sample per °Brix: P.E. Units per °Brix = [(milliliters of 0.02 N NaOH) x 0.02]/[(°Brix of Sample) x 100]

Claims: A method for preparing a commercial feed juice from orange fruit which comprises the processes of juice extraction from selected fruit (I), removal of rag and seed (II), and separation of feed juice from pulp (III), and removing some of the sinking pulp (IV), characterised in that (I) juice is extracted using a Low Oil Juice extractor or a commercial juice extractor with a prior de-oiling step yielding a titratable peel oil level of 0.006% to 0.015%, rag and seed are removed (II) not more than 3 minutes after the extraction step (I), sensible pulp (ie pulp > 0.5mm) is removed to provide a juice having at least 10% sinking pulp (ie pulp <0.5mm), and reducing the level of sinking pulp that remains in the feed juice to between 5 and 10% (IV). The method of claim 1 wherein the juice extraction of step (I) is carried out to yield a level of titratable peel oil of from 0.006% to 0.010%. The method of claim 1 wherein the commercial juice extractor is a reciprocating cup-type and wherein the juice yield is from 90% to 95% The method of claim 1 or 2 which comprises the further step or deoiling the selected fruit prior to the juice extraction in step (I). The method of claim 1 wherein the commercial juice extractor is a reamer-type or rotating disc-type and wherein step (II) is carried out with a vibrating screen. A commercial Valencia orange feed juice which is substantially free of sensible pulp and which has: a) a viscosity of about 10 mPas (10 centipoise) or less at a temperature of 8°C, b) from 7% to 10% sinking pulp, c) from 0.006% to 0.010% of titratable peel oil d) less than 175mg per 100ml of flavinoid glycosides. The feed juice of claim 6 wherein the ratio of the combined amount of acetaldehyde, methanol, ethyl butyrate, ethyl 3-hydroxyhexanoate and valencene, to the combined amount of hexanal, alpha -pinene, myrcene, decanal, linalool and octanal in the feed juice is from about 8.5 to about 21.5.

Inventors: POWERS, JOHN R., STIPP, GORDON K., STROBEL, RUDOLF G.K., TSAI, CHEE-HWAY
Applicants: THE PROCTER & GAMBLE COMPANY
Application year: 1988
Main classification: A23L2
IPC codes: A23L2