Food products for long storage at room temperature and method for same

Abstract: Food products for long storage at room temperature are prepared by a process of; drying ingredients until water content thereof is less than 15 wt%, heating several kinds of fats and oils which form solids or semi-solids until the contents are melted completely then cooled to prepare fatty liquid impregnating the fatty liquid into the dried ingredients, and sealing the products in the small packages. While producing, water activity of products are regulated in a range of 0.55 to 0.75 in order to inhibit the blocking and generation of microorgasms.

Description: BACKGROUND OF THE INVENTION Technical Field This invention relates to food products utilized in instant cooking having the ability to be stored for long periods without need of high temperature sterilization. Specifically it relates to oil impregnated food products which retain the material color and flavor of their raw ingredients. Background Art Methods of producing storable sterilized and sealed foods such as canning, bottling and retorting have been utilized broadly over the last 150 years and have been applied to fruits, vegetables, meat, marine products, and cooked products and so on as safety foods. They can be distributed at room temperature because microbiological resistance and sterility make it possible to store them for long periods of time at room temperatures. In sterilized and sealed foods such as the above mentioned, storageability is definitely influenced by whether or not the sterilization after sealing is perfect. Generally, the means for sterilization utilized in the industrial field is wet heating sterilization by vapor. It is used for the purpose of establishing sanitary conditions by destroying all toxic and nontoxic microorganisms that are generated in foods under storage without cooling or generated in the course of distribution. Suitable heating conditions for the above mentioned are varied by the pH and water activity of the products, heat resistance of microorganisms, packaging size and the physical properties of the foods. Particularly, pH and water activity are influential elements for microorganism generation. Acid foods having pH values of less than 4.6 such as canned fruits are low temperature sterilized at temperatures less than 100 o C, and low acid foods having pH in a range of 4.6 to 8.0 such as canned marine products are high temperature sterilized at temperatures more than 100 o C. It is well known that the generation of microorganisms which can decompose canned foods are commanded by water activity at a border value of 0.93 or 0.94. According to the Food Sanitation Act of Japan, it is necessary to apply heat sterilization of at least 120 o C for 4 mins. (this is necessary for destroying botulism bacillus) when producing food products having a pH of more than 5.6 and water activity of more than 0,94. Most canned foods are wet, low acid foods having water activity of more than 0.94 with pH values in a range of 4.6 to 8.0. Therefore, they need heat sterilization as described above. However, when using perishable materials characterized by fresh flavor and vivid color, heat sterilization causes several problems. That is to say, denaturation of protein and decomposition of pigment occur as a result of heat sterilization, this and other influences damage the raw material's precious flavor and color. Therefore, supplying these kinds of food products in canned form under room temperatures is very difficult. Japanese Patent First Publication No. 59-34874 discloses a method for producing food products by adding etylalcohol to pastes after cooking. Japanese Patent First Publication No. 61-31039 and No. 63-279770 disclose methods for producing sauce or suspension that is first cooled suddenly, whereupon a mixture of heated oils is kneaded thereinto, followed by addition of an emulsifying agent. U.S. Patent No.4,746,524 discloses a method for producing food products by adjusting the pH values while also adjusting the water activity of the ingredients of the food products. U.S. Patent No. 3,769,042 discloses a method for food products by immersing solid pieces in a liquid phase gravy or sauce comprising an aqueous solution of stabilizing solutes to infuse a portion of the solutes into the solids phase to the extent of reducing water activity of the solids phase to a level ranging from about 0.6 to 0.9 and forming surrounding liquid phase gravy to have residual stabilizing solutes such that water activity of the liquid phase differs from the water activity of the solids phase by less than 0.1. Though food products produced by the above mentioned methods have adequate microorganism resistance, relative long storage ability and retention of flavor in the raw materials thereof, further storage ability at room temperatures and restoration ability are needed. Additionally, food products for instant cooking by mixing them with materials such as boiled noodles and rice using oil for cooking are needed. It is well known that lowering the water activity of products inhibits generation of microorganisms necessary as previously mentioned for long storage. Products that are merely dried are different from the raw materials before drying in flavor, color, taste and so on. It is also well known that storage methods such as salting, pickling, miso pickling, sweetening and so on greatly change the material's taste. Therefore, these methods of raising osmotic pressure can be applied for only certain types of food products. Other methods for producing storable food products are disclosed in GB-A-1 113 435, FR-A-2 602 398 and US-A-3 966 993. GB-A-1 113 435 describes a process for improving the stability of dried plant tissue which has been dehydrated and comminuted. The plant tissue is mixed with an edible fat and/or oil in the liquid state at a temperature below that at which the plant tissue is substantially degraded. In example 3 dried comminuted spices having a moisture content of less than 9 wt% were mixed with melted beef suet and then, dried comminuted parsley was added to this mixture which was subsequently mixed for a further period of time. This product was found useful as a source of mixed spices in a powdered savoury food. The description makes no reference to regulation of water activity in the final product. FR-A-2 602 398 describes a shelf-stable dough product having a shelf life of at least 12 months. The dough product is an intermediate moisture dough made principally from inactivated flour and in which the water activity value is fixed in an optimum range of between 0.60 to 0.80. For the increased shelf stability use of inactivated flour is relied on. The flour was obtained by first steam treating the grain, then cooling and pre-drying it before crushing. The flour was subsequently sifted and dried to a water content of between 3 to 6%. The product was not subjected to impregnation with a fatty liquid to increase shelf life. US-A-3 966 993 describes a process for making a solid sauce bar by mixing fat, flour and condiments, tempering the mixture and subsequently casting and cooling the bar until it is dimensionally stable at room temperature. The document does neither disclose impregnation of the starting products with a fatty liquid nor regulation of water activity in the final product. In the light of the above mentioned background, it is the object of this invention to provide new food products for instant cooking which can retain the raw ingredient's natural flavor and color and methods of producing same. It is another object of this invention to provide new food products which can be stored for long periods of time at room temperatures and methods of producing same. It is a further object of this invention to provide new food products without sterilizing at high temperatures and methods of producing same. SUMMARY OF THE INVENTION This invention takes advantage of the properties of oil. Properties that provide a coating which can not be oxidized easily and can provide moisture to dried materials. Raw materials such as fruits, vegetables, meat, marine products are dried until having less than or equal to 15 wt% of water in them. Fatty liquid from a mixture of fats and/or oils which forms a solid or paste (semi-solid) at room temperatures is heated and melted, then cooled until less than or equal to 60 o C. After the cooling of the fatty liquid the dried materials are added and mixed. At this stage, the products' water activity is regulated in a range of 0.55 to 0.75. When these products are completed, they are sealed in appropriate packaging. According to this invention, a method for producing flavorful and colorful products keeping the properties of their raw material's without sterilizing at high temperatures can be provided. They can be stored for long periods of time at room temperatures because of addition of oil for moisture sealing and imparted relative stability against moisture or oxidation. This has not been realized by prior arts such as canning or retorting foods. Food produced according to the invention contain plenty of fat and oil of their own, the invention has extensive utility in producing sauces or other ingredients using oil for cooking. By applying this invention, the variety of easily available foods, convenient in preparation and storage, can be greatly increased, more plentiful. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The following discussion concerns the details of the preferred embodiment according to the present invention. The invention includes food products which retain the flavor and color of their raw materials at room temperatures for long periods of time. The products are impregnated with oil, and water activity thereof is regulated in a range of 0.55 to 0.75. Water activity (hereinafter referred to as Aw) is the unit which indicates the presence of water in foods can be described by the following formula: Aw = P/Po (P:vapor pressure of food, Po:vapor pressure of pure water) In food products produced according to the present invention, Aw is determined in a range of 0.55 to 0.75, because generation of microorganisms cannot be substantially prevented when Aw is more than 0.75. Additionally, at room temperature storage, there is a possibility of pollution not only be yeasts or molds but also be halophilic bacteria when Aw is more than 0.75. If Aw is less then the maximum value as mentioned above, storageability is obtained much like that in ordinary keepable foods sterilized at room temperatures (less than 100 o C) but without losing the raw ingredients' flavor. On the other hand, if Aw is less than 0.55, salt, sugar or other sweetening agents, polyalcohols and chemical seasonings utilized in cooking cannot be dispersed uniformly in the material. Therefore, in an industrial process, clogging occurs in packing systems. Furthermore, when using small package such as aluminium pouches, crystals of the added seasonings cause poor sealing or leaking of the liquid in the package. In order to prevent the occurrence of these disadvantages, there is the method of previously pulverizing such materials. However, these particles absorb small quantities of water in the reaction system and form crystallike blocks having a diameter of more than 2 mm which are called "blocking". Therefore, it causes packing difficulty and besides it has an unpleasent texture in the mouth because of this crystalization. Therefore, foods which are impregnated with oil can promote fluidity of liquid in a package and concurrently cause no blocking when Aw is determined higher than 0.55. According to the previously mentioned considerations, in the present invention, raw materials having nearly 1.0 of Aw are dried until less than 15 wt% of water remains in order to obtain the above mentioned range of Aw. Then these materials are impregnated with a molten mixture of fats and oils forming a solid or paste (semi-solid) at room temperatures. By this process the fatty liquid is absorbed by the dried materials in place of water, by this process raw flavor of the materials can be restored. The method for drying is not specifically limited and may be such as hot-air drying, freeze-drying, far infrared-drying or so on. Drying is generally performed so as to leave less than 10 wt% of water in the materials, because it is difficult to lower the Aw below 0.75 when water in the materials is more than 15 wt%, and the total wt% may be slightly changed by the amount of added seasonings. On the other hand, small amounts of water may be added in order to regulate Aw when the materials are overdried or the Aw of the materials becomes less than 0.55 due to the adding of small amounts of seasonings. Materials which can utilized in the present invention are all eatable solids which are derived from animals or plants. Generally, beef, pork, chicken, eggs, fish, roe, shellfish, shrimp, crab, vegetables mixtures containing bamboo shoots or udo, fruits, nuts, spices, whole or parts of sea weeds and dairy products such as cheese are utilized as materials. A mixture of Fats and oils in the form of a solid or paste at room temperatures is used as base agent in the present invention. Edible animal and plant oils such as palm, cottonseed, rape, peanut, sesame, palm core, almond, bean, safflower, sunflower, tallow, lard, or separation of these oils, random ester exchanged oil, hardened oil or a blend of the same, oil products such as butter, margarine, shortening or so on can be used. Fats and oils having a low exchange of density by temperature are preferable. This is indicated by SFI (solid fat index) line crossing the temperature axis as perpendicularly as possible. Margarine which is sold on market is preferable in the light of the invention's object because its density exchange is regulated by temperatures as small as possible by ester exchange, etc. However, margarine containing natural butter contains a considerable amount of water, consideration of water content is necessary when utilizing this type of margarine. On the other hand, mixtures of liquid oils such as salad oil and pasty fats such as middle m.p. fractions of palm oil can provide desired density without consideration of water content. In order to impregnate the dried materials with fats and oils as mentioned, the materials are added to the fatty liquid from a mixture of fats and oils under temperature conditions of less than 60 o C, then mixed until they are dispersed sufficiently. By this process, the tissue structure of the materials is impregnated with fatty liquid and their flavor and color are restored. In the present invention, besides the materials and oils as previously mentioned, seasonings such as salt and sugar, many kinds of spices and flavorings can be added to taste for the purpose of controlling the flavor of the food products. These seasonings may be added to the ingredients before drying or during the impregnation period. Additionally, small amounts of natural or synthetic antioxidant can be added to inhibit formation of peroxide due to the oxidation of fats and oils. The food products of the present invention have long storageability. They are not denatured or decomposed while being stored and do not oxidize suddenly or absorb moisture because the materials are surrounded by fat and oil. However, in order to prevent pollution or moisture absorption through dust in the air, the products are preferably wrapped lightly using materials such as cellophane having moistureproof properties. Furthermore, even with fat and oil surrounding the materials, this coating will oxidize over very long periods of time. Therefore, the products should be sealed and packed in long term storable casings such as cans, bottles or aluminium pouches. In this case, high temperature sterilizing is not necessary, but if desired, low temperature sterilizing may be performed. Furthermore, when low temperature sterilizing is performed, vacuum treating or heat-packing at low temperature can be performed as desired. EXAMPLES The following examples are disclosed for the purpose of giving a more detailed description. 〈Example 1〉 Japanese style spaghetti sauce "mentaiko" (cod or pollack roe in red pepper sauce). 50 kg of palm oil and 18 kg salt-free butter were mixed then heated and stirred into kneader (of the steam heated, water cooled type) until the oil and butter were melted completely. After melting, 29 kg of cottonseed oil and 0.5 kg of butter flavoring and the same amount of cod roe flavoring were added and mixed uniformly. Then the mixture was cooled by stirring until the temperature became less than 35 ° C. 12 kg of chemical seasoning, 40 kg of pure salt, 35 kg of granulated sugar and 55 kg of raw pollack roe in red pepper sauce (dried by hot air at 80 ° C for 3 hours at which water content was regulated to 7 wt%) was added to the previously mentioned mixed oil. Furthermore, 25 kg of water was added to this mixture then stirred and mixed until all the ingredients were dispersed in the oil mixture completely. The obtained sauce was packed and sealed into small aluminium pouches using a small-package machine, each containing 15 g of sauce. Delicious Japanese style spaghetti having the flavor, color and taste of raw pollack roe was obtained when boiled spaghetti was dressed with this packed sauce. Measured Aw of this example's sauce is shown in Table 1. 〈Example 2〉 Genoese style basil sauce for pasta. 70 kg of palm oil and 50 kg of salt-free butter were mixed in the kneader then heated and melted. After it melted completely, 20 kg of olive oil was added and mixed uniformly and cooled by stirring until the temperature became less than 35 ° C. 10 kg of chemical seasoning, 45 kg of pure salt, 38 kg of granulated sugar, 22 kg of freeze-dried raw basil in which water content was regulated to 4 wt% and 20 kg of pine seeds chopped into 2 mm squares were added to the mixed oil. Furthermore, 25 kg of water was added then stirred and mixed until the all materials were dispersed in the oil mixture completely. Then, packing and sealing in aluminium pouches was done, each pouch containing 15 g of sauce, a Genoese type basil sauce for pasta was obtained. When sampling boiled spaghetti dressed with this sauce, the flavor and color of the basil was restored excellently. Aw measured of this sauce is shown in Table 1. 〈Example 3〉 Chinese dish of fried rice with roast pork. 30 kg of lard, 40 kg of beef fat, 35 kg of salad oil were mixed in a direct boiling style pot with a mixer, then heated and melted until all ingredients were melted completely. After a uniform dispersion was completed, the mixture was cooled by stirring until the temperature became less than 40 ° C. 36 kg of chemical seasoning, 50 kg of pure salt, 25 kg of granulated sugar, 18 kg of freeze-dried roast port cubed to 5 mm size in which water content was regulated to 5 wt% and the same amount of dried onion also cubed to 5 mm size in which water content was regulated to 7 wt% was added to the mixed oil and fat. Then furthermore, 40 kg of water was added and stirred until the all materials were dispersed in the oil mixture completely. The obtained stock were packed and sealed into aluminium pouches of 10 g each by a small package machine. A dish of Chinese fried rice with fully restored roast pork flavor and natural vegetable taste was obtained when frying cold rice with this stock. Measured Aw of this stock is shown in Table 1. 〈Example 4〉 Sauce of chow mein with ingredients. 50 kg of lard, 50 kg of salad oil and 20 kg of salt-free butter was added in a direct boiling style pot then heated and melted until all materials were melted completely. Afterwards, the molten mixture was moved into a pan with a mixer, then cooled by stirring until the temperature became less than 30 ° C. 5 kg of beef particles extract, 5 kg of chemical seasoning, 45 kg of pure salt, 25 kg of sugar, 10 kg of freeze-dried (according to the usual method) pork cubes of 5 mm size in which water content was regulated to 12 wt%, 5 kg of cut in desired size and dried cabbage in which water content was regulated to 10 wt%, 2 kg of green laver, 1 kg of dried ginger cubed to a 10 to 20 x 2 x 2 mm size in which water content was regulated to 8 wt% and 30 kg of Worcester sauce were added to the previously mentioned mixed oil. Then the mixture was stirred and mixed until the all materials were dispersed in the oil mixture completely. The obtained sauce was packed and sealed into aluminium pouches of 20 g each by a small-package machine. A chow mein with ingredients having good flavor was obtained when the sauce was melted completely in a frying pan and fried with raw mein or chow mein over medium heat for 3 min. Measured Aw of this sauce is shown in Table 1. Example No. 1 2 3 4 Aw 0.57 0.60 0.72 0.68 Several combinations arrangements of ingredients ratios for Examples 1 and 2 were performed in the laboratory scale. The results are shown in Tables 2 and 3. Other combinations of Example 1. Combinations Materials (kg) A B C D E Dried pollack roe 21 21 21 21 21 Palm oil 20.4 19.4 19.8 18.8 17.8 Cottonseed oil 11 11 11 11 11 Salt-free butter 6.8 6.8 3.4 3.4 3.4 Butter flavoring 0.2 0.2 0.2 0.2 0.2 Cod roe flavoring 0.2 0.2 0.2 0.2 0.2 Pure salt 20 15 15 15 15 Granulated sugar 13 13 13 13 13 Chemical seasoning 4.4 4.4 4.4 4.4 4.4 95% of alcohol -- -- 10 -- -- Water 3 9 2 13 18 Sum (kg) 100 100 100 100 100 Occurrence of blocking Y N N N N Aw 0.52 0.57 0.65 0.70 0.82 Generation of mold or yeast (/ml) <300 <300 <300 <300 2.5 x10⁷ Other combinations of Example 2. Combinations Materials (kg) F G H I J Pine seeds 20 20 20 20 20 Dried basil 22 22 22 22 22 Palm oil 90 85 70 62 55 Olive oil 20 20 20 20 20 Salt-free butter 50 50 50 50 50 Pure salt 45 45 45 45 45 Granulated sugar 38 38 38 38 38 Chemical seasoning 10 10 10 10 10 White wine -- 10 -- -- -- Water 5 -- 25 33 40 Sum (kg) 300 300 300 300 300 Occurrence of blocking Y Y N N N Aw 0.49 0.53 0.66 0.71 0.78 Generation of mold or yeast (/ml) <300 <300 <300 <300 7.0 x10⁷ Referring now to Tables 2 and 3, blocking of products occurred when Aw was less than 0.55. On the other hand, mold or yeast was generated when Aw was more than 0.75. Therefore, ingredient ratios can be varied without departing from an Aw range between 0.55 and 0.75.

Claims: A method for producing oil based food products, which are storable at room temperatures; wherein said method comprises the steps of: drying eatable solids to have less than or equal to 15 wt% of water therein; preparing a fatty liquid from a mixture of fats and/or oils which forms a solid or a semi-solid at room temperature, by heating and melting said mixture and then cooling it to a temperature less than or equal to 60° C; adding said dried eatable solids to the fatty liquid and mixing it until the solids are dispersed sufficiently in the fatty liquid, in order to impregnate said fatty liquid into said dried solids; regulating the water activity of said products in a range of from 0.55 to 0.75; and packing said products in a casing to be sealed. A method according to claim 1; wherein said method comprises adding seasonings to said eatable solids. A method according to claim 1; wherein said method comprises adding seasonings to said products while impregnating. An oil based food product being storable at room temperatures and being composed of: dried materials prepared by drying eatable solids until having less than or equal to 15 wt% of water therein; and a mixture of fats and/or oils which forms a solid or a semi-solid at room temperature; wherein said mixture of fats and/or oils is heated to melt completely and cooled to a temperature of less than or equal to 60° C for impregnating into said dried materials; wherein said dried materials are substantially uniformly dispersed in said mixture of fats and/or oils, in order to impregnate said mixture into said dried materials; and wherein said product has a water activity regulated in the range of 0.55 to 0.75 and is contained in a sealed casing. A food product according to claim 4; wherein said product comprises seasonings added to said eatable solids. A food product according to claim 4; wherein said product comprises seasonings added to said product while impregnating.

Inventors: SUZUKI KAZUJI, UEDA YASUO, SUZUKI, KAZUJI, UEDA, YASUO
Applicants: SUNTORY LTD, SUNTORY LIMITED
Application year: 1989
Main classification: A23L3
IPC codes: A23B7, A23L1, A23L3, A23B4