FAT COMPOSITION AND FROTHING OIL-IN-WATER EMULSION

Abstract: A frothing oil-in-water emulsion having excellent heat resistance and good meltability on the tongue, freshness and coolness, and a fat composition most suited for the production thereof. The composition is prepared by mixing a lauric fat or a hardened oil thereof with a C₁₆₋C₂₄ fatty acid or its ester or a fat rich in glycerides having C₁₆₋C₂₄ fatty acid residues, effecting the transesterification of the obtained mixture by the well-known method in the presence of a lipase having a specificity for the 1- and 3-positions of glycerides, and if necessary conducting extreme hardening by the conventional method, whereby a fat composition comprising glycerides having the total number of the carbon atoms of the constituent fatty acid residues of 38 or less, 42 to 46, and 48 or above, respectively, in amounts of 25-50 %, 25-40 %, and 5-25 %. The emulsion is prepared from this composition.

Description: TECHNICAL FIELD The present invention relates to a fat composition which has a specific composition, and a whippable oil-in-water (o/w) emulsion prepared by using the fat composition. PRIOR ART A large amount of laurin fats, such as coconut oil and palm kernel oil, and their hydrogenated products have been used in whippable creams, such as whipping cream. Cream prepared by using these fats, alone or with natural fresh cream, has been used for example for cake icing. Many of them have qualities superior in their physical properties to natural fresh cream, such as excellent melting properties in the mouth, freshness and cold feeling, but there are still various features to be improved. A particular problem of whipped creams is their poor heat resistance. Especially in summer, whipped cream causes deformation and syneresis, when used for example to decorate cakes. Laurin fats, especially coconut oil, contain only a small amount of long-chain unsaturated fatty acids, such as oleic acid and linoleic acid. Therefore, their heat resistance is not significantly improved even when extremely hydrogenated. In addition, a method is known for enhancing the heat resistance of laurin fats by adding a high melting point fraction of liquid oils or extremely hydrogenated oils to laurin fats, but it is known that this method degrades the melting properties of the cream in the mouth. Though attempts have been made to obtain a margarine hardstock fat by introducing long-chain fatty acids to laurin fat (EP 0170431), no attempts have been made to improve melting properties in the mouth and heat resistance of a whippable cream. DISCLOSURE OF THE INVENTION The present invention provides a whippable o/w emulsion which has good heat resistance and excellent melting properties in the mouth. It is believed that excellent melting properties in the mouth, freshness and the cold feeling of a whippable o/w emulsion prepared by using laurin fats are derived from middle-chain fatty acids with 8-12 carbon atoms. Hence, the inventors have found that a novel fat composition can be prepared by preserving middle-chain fatty acids, which occupy more than half of the fatty acids especially in their 2-position as they are, and introducing a small amount of long-chain fatty acids with 16 or more carbon atoms to the fats, and that thereby a whippable o/w emulsion, to which are imparted excellent melting properties in the mouth and heat resistance, can be prepared. Specifically, the present invention relates to a fat composition containing 25-60% of glycerides, of which the constituent fatty acid residue has not more than 38 total carbon atoms, 25-50% of glycerides, of which the constituent fatty acid residue has 42-46 total carbon atoms, and 5-25% of glycerides, of which the constituent fatty acid residue has not less than 48 total carbon atoms. Also the present invention relates to a whippable o/w emulsion prepared using the above fat composition. The fat composition of the present invention contains 25-60% of glycerides of which the constituent fatty acid residue has not more than 38 (normally 30-38) total carbon atoms, 25-50% of glycerides of which the constituent fatty acid residue has 42-46 total carbon atoms, and 5-25% of glycerides of which the constituent fatty acid residue has not less than 48 (normally 48-56) total carbon atoms. The % value indicating a distribution of number of carbon atoms in the glyceride is weight %. That is, the fat composition of the present invention is novel in that the content of glycerides, of which the constituent fatty acid residues have not less than 38 total carbon atoms, is less than that in laurin fats and is equal to that in milk fat, and the content of glycerides, of which the constituent fatty acid residues have 42-46 total carbon atoms, is more than that in laurin fats and milk fats, and that the content of glycerides, of which the constituent fatty acid residues have not less than 48 total carbon atoms, is less than that in milk fats and more than that in laurin fats. The whippable o/w emulsion prepared using this fat composition has excellent melting properties in the mouth, freshness, cold feeling, and good heat resistance. When the content of glycerides, of which the constituent fatty acid residues have not less than 48 total carbon atoms, are in excess, the whippable o/w emulsion has good heat resistance, but has inferior melting properties in the mouth. Therefore, to improve both heat resistance and melting properties in the mouth, the content of glycerides, of which the constituent fatty acid residues have 42-46 total carbon atoms, and glycerides, of which the constituent fatty acid residues have not less than 48 total carbon atoms, should be in the range mentioned above. The fat composition of the present invention has the following properties when prepared according to the process described below: more than 40%, preferably more than 50% fatty acids at the 2-position of the triglycerides is lauric acid, and the 1,3-fatty acids are randomly distributed between these positions. Also, the solid fat content (SFC) is 45-70% (at 20 °C) and 10-45% (at 30 °C). The slipping point (in the United States called the Softening point) is 35-45 °C. An example of the preparation of the fat composition of the present invention is as follows: The fat composition is prepared by mixing laurin fats or hydrogenated forms thereof with fatty acids containing 16-24 carbon atoms or esters thereof, or fats rich in glycerides which contain fatty acid residues with 16-24 carbon atoms, transesterifying them by a conventional method, in the presence of a lipase having 1,3-specificity, and subjecting them to extreme hydrogenation according to a conventional method, if required. As for laurin fats, it is most preferred that coconut oil or a hydrogenated form thereof, wherein lauric acid is most abundant at the 2-position, is used. As for fatty acids with 16-24 carbons or esters thereof, stearic acid, palmitic acid, or the ethylester or methylester thereof are examples. As for fats rich in glycerides which contain fatty acid residues with 16-24 carbon atoms, vegetable oils, such as soybean oil, rape seed oil, palm oil or fractionated oils thereof are examples. More specifically, when laurin fats or hydrogenated products thereof, and fatty acids or esters thereof are the raw materials, it is preferred to mix them at a weight ratio between 60:40 and 80:20 (laurin fats or hydrogenated forms thereof : fatty acids or esters thereof). When laurin fats or hydrogenated products thereof, and fats rich in glycerides which contain fatty acid residues with 16-24 carbon atoms are the raw materials, it is preferred to mix them at a weight ratio between 70:30 and 90:10 (laurin fats or hydrogenated products thereof : fats rich in glycerides with fatty acid residues containing 16-24 carbon atoms). As for lipases specific to the 1,3-positions, known ones, for example from Rhizopus , Aspergillus , Penicillium , Candida , Pseudomonas , or Mucor , can be used. Procedures for lipases having 1,3-selectivity, lipase preparations, or methods of transesterification using them, can be performed, according to the procedures described in, for example, JP,A,52-104506, JP,A,55-71797, JP,A,55-84397, JP,A,56-127094, JP,A,56-163196, JP,A,57-78496, JP,A,59-500649, JP,A,60-19495. When the fat composition is prepared by random transesterification, the composition will contain a large amount of triglycerides, such as tristearin, wherein each constituent fatty acid is long-chain and contains 16-24 carbon atoms. The whippable o/w emulsion prepared by using such a fat composition will have heat resistance, but will have inferior melting properties in the mouth. When the content of triglycerides, which contain both long-chain fatty acids and middle-chain fatty acids, i.e. triglycerides comprising fatty acids with different chain lengths, is increased, "firmness" of the whippable o/w emulsion (crumbling, making handling difficult) will be prevented. Hence, it is preferred that transesterification selective to the 1,3-positions is carried out. When laurin fats rich in glycerides which contain fatty acid residues with 16-24 carbons are the raw materials, it is preferred that extreme hydrogenation is carried out after transesterification of the mixed fats. When separately hydrogenated fats are transesterified, elevation of the reaction temperature and use of solvents are required, which results in a cost disadvantage. Hence, it is preferred that the fats are subjected to extreme hydrogenation after transesterification. Such a fat composition obtained as described above may be used to prepare a whippable o/w emulsion. In the present invention, a "whippable o/w emulsion" is a creamy material, prepared by processing basic materials (the fat composition mentioned above, proteins, sugars and water) to form an emulsion with the aid of an emulsifier. It is also called "whipping cream". When the whippable o/w emulsion is whipped by a foaming apparatus or a mixer for foaming, it becomes what is called "whipped cream or "whip cream". The fat content of the foamable o/w emulsion of the present invention is normally in a range of 20-50% based on the whole emulsion. As proteins, many proteins from non-fat solids are normally used. Non-fat solids are necessary to stabilize the emulsified state as an o/w emulsion as well as to impart milk flavor to the cream. Examples of these non-fat solids are skim milk powder, whole milk powder, raw cream, milk and sweetened condensed milk. Other proteins, such as casein, lactalbumin and vegetable proteins can be used. Alternatively, skim milk powder or whole milk powder may be Maillard-treated. Such non-fat solids may be used in an amount of 1-15%, preferably 3-8% based on the total weight. Sugars are essential when the whippable o/w emulsion of the present invention is transported as fillings for breads or cakes at room temperature or under chilled condition. That is, to preserve the whipped materials for a long time, a decrease in water activity is required. Therefore, addition of sugars is needed. Examples of sugars are glucose, maltose, sorbitol, sucrose, fructose, saccharified reduced starch and various thick malt syrups. One of these sugars may be used, or more than one of them may be mixed to be used. In such cases, it is preferred that the amount of sugars to be added is less than 50% based on the whole emulsion, calculated on the anhydrous material, and that a suitable amount of sugars is added according to the use. When more than 50% of sugars are used, viscosity of the whippable o/w emulsion increases, and various problems, such as difficulty in transportation by pump in the production step, will occur. Furthermore, emulsifiers, various salts, stabilizers and flavors, which are used in known synthetic creams, may be included in the whippable o/w emulsion. As emulsifiers, for example, suitable amounts of soybean lecithin, sucrose fatty acid ester, polyglycerin fatty acid ester and sorbitan fatty acid ester may be used. As salts, for example, suitable amounts of alkali metal salts of phosphoric acid and alkali metal salts of citric acid may be used. As stabilizers, for example, suitable amounts of xanthan gum and guar gum may be used. The whippable o/w emulsion of the present invention can be prepared according to procedures for preparing normal creams or imitation creams, and can be sterilized if necessary. Homogenization or stirring can be performed after or before sterilization. Homogenization may be done by either pre-homogenization or post-homogenization, or else a combination of both. The whippable o/w emulsion prepared as described above is suitable as fillings in breads and cakes, and can be used as a nappe for a normal decorated cakes or as a cream for preparing imitation flowers. BEST MODES OF THE INVENTION As embodiments of the invention, fat compositions and whippable o/w emulsions were prepared by conventional methods according to Example 1. Furthermore, the occurrence of a thickened state after incubating the whippable o/w emulsions at 20 °C for 2 hours and stirring them, over-run after foaming them for 5 minutes using a Kenwood mixer, syneresis and maintenance of shape at 20-30 °C, and melting properties in the mouth, were estimated. Results obtained from comparative experiments are also described in Comparative Examples 1 and 2. The following examples are to be construed as merely illustrative, and not to be limiting of the scope of the invention. In addition, parts in the formulations are represented by weight. Example 1 Eighty parts of palm oil were mixed with 20 parts of rape seed oil, and transesterification selective to the 1,3-positions was performed; then extreme hydrogenation was carried out by a conventional method to obtain a fat composition (fat A). The composition and physical properties of fat A are shown in Table 1. Then, according to the formulation below, a whippable o/w emulsion was prepared using fat A. Firstly, an oily phase was prepared by warming fat A to 70 °C, and adding soybean lecithin thereto. Separately, an aqueous phase was prepared by warming water at 60 °C, adding sodium hexametaphosphate and sodium bicarbonate thereto to be dissolved, then dissolving or dispersing therein skim milk powder, thick malt syrup and sorbitol in that order. Then, the oily phase and the aqueous phase were mixed together, and sucrose fatty acid ester, xanthan gum and flavor were added thereto, and the mixture was stirred and pre-emulsified at 65-70 °C for 20 minutes using a homomixer. Thereafter, the mixture was homogenized under a pressure of more than 100 kg/cm 2 , treated by ultra high temperature sterilization (UHT) at 140-150 °C for 4 seconds, and again homogenized under a pressure of 45 kg/cm 2 , cooled to 12 °C, then subjected to aging. An estimation of the properties of the whippable o/w emulsion prepared is shown in Table 2 Formulation (%; w/w) fat A 23.6% skim milk powder 4.0% sugars 35.0% water 36.04% emulsifier 0.58% stabilizer 1.38% salts 0.32% flavor 0.08% Example 2 A fat composition (fat B) was prepared by mixing 70 parts of hydrogenated palm oil with 30 parts of stearic acid, and transesterifying selectively at the 1,3-positions of the glycerides. The composition and physical properties of fat B are shown in Table 1. Then, a whippable o/w emulsion was prepared according to Example 1, except that fat B was used instead of fat A. An estimation of the properties of the whippable o/w emulsion prepared is shown in Table 2. Example 3 A fat composition (fat C) was prepared by mixing 70 parts of palm oil with 30 parts of rape seed oil, transesterifying selectively at the 1,3-positions, and performing extreme hydrogenation by a conventional method. The composition and physical properties of fat C are shown in Table 1. Then, a whippable o/w emulsion was prepared according to Example 1, except that fat C was used instead of fat A. An estimation of the properties of the whippable o/w emulsion prepared is shown in Table 2. Comparative Example 1 A fat composition (fat D) was prepared by mixing 60 parts of coconut oil with 40 parts of rape seed oil, transesterifying selectively at the 1,3-positions, and performing extreme hydrogenation by a conventional method. The composition and physical properties of fat D are shown in Table 1. Then, a whippable o/w emulsion was prepared according to Example 1, except that fat D was used instead of fat A. An estimation of the properties of the whippable o/w emulsion prepared is shown in Table 2. Comparative Example 2 One hundred parts of coconut oil was subject to extreme hydrogenation to obtain fat E. The composition and physical properties of fat E are shown in Table 1. Then, a whippable o/w emulsion was prepared according to Example 1, except that fat E was used instead of fat A. An estimation of the properties of the whippable o/w emulsion prepared is shown in Table 2. Referring to Table 2, the whippable o/w emulsions from Examples 1-3 had good heat resistance and excellent melting properties in the mouth. The whippable o/w emulsion from Comparative Example 1 had heat resistance as good as from Examples 1-3, but had inferior melting properties in the mouth; therefore it was not acceptable as food. The whippable o/w emulsion from Comparative Example 2 had melting properties as good as from Example 1-3, but had very poor heat resistance. ADVANTAGES OF THE INVENTION The present invention provides a whippable o/w emulsion for use in for example whipping cream, which possesses good heat resistance as well as excellent melting properties in the mouth, freshness and cold feeling, and provides a fat composition suitable to be applied to an emulsion. Compositions and physical properties of fats A-E fat distribution of number of carbon atoms SFC(%) slipping point(°C) -38 42-46 48- 20°C 30°C Example 1 A 39.9 33.0 13.8 63.6 32.6 36.2 Example 2 B 34.5 36.6 17.3 63.4 37.7 36.0 Example 3 C 30.5 36.4 22.0 68.2 39.7 42.0 Comparative Example 1 D 22.5 38.5 28.5 72.0 46.0 46.0 Comparative Example 2 E 75.8 11.0 2.3 45.4 7.5 31.0

Claims: A fat comprising 25-60 weight % of glycerides of which the constituent fatty acid residue has not more than 38 total carbon atoms, 25-50 weight % of glycerides of which the constituent fatty acid residue has 42-46 total carbon atoms, and 5-25 weight % of glycerides of which the constituent fatty acid residue has not less than 48 total carbon atoms. A fat composition as claimed in claim 1 wherein more than 40 weight % of the fatty acids at the 2-position of the glycerides is lauric acid, the solid fat content (SFC) is 45-70 weight % at 20 °C and 10-45 weight % at 30 °C, and the slipping point is 35-45 °C. A whippable oil-in-water emulsion comprising a fat composition as claimed in claim 1 or claim 2. A whippable oil-in-water emulsion as claimed in claim 3 containing 20-50 weight % of fats and oils and 1-15 weight % of non-fat solid. Food products when comprising a whippable oil-in-water emulsion as claimed in claim 3 or claim 4.

Inventors: HIDAKA HIROSHI, INAYOSHI KUNIAKI, NISHIMOTO TUGIO, YABUUCHI SAYOKO, HIDAKA, HIROSHI, INAYOSHI, KUNIAKI, NISHIMOTO, TUGIO, YABUUCHI, SAYOKO
Applicants: FUJI OIL CO LTD, FUJI OIL COMPANY, LIMITED
Application year: 1993
Main classification: A23D7
IPC codes: A23D7, A23L1, C11C3, A23D9