JPH0160222B2 - - Google Patents

Description

[Detailed description of the invention]

(Field of Industrial Application) The present invention relates to a tofu snack whose main ingredient is a freeze-dried product with a new morphology obtained by rapidly freezing soybean milk gel or tofu and vacuum freeze-drying, and a method for producing the same. be. (Prior Art) As is well known, so-called tofu consists of approximately
It is a food that is 90% water and also contains a considerable amount of water, making it unsuitable for consumption in any form other than cooking food. On the other hand, frozen tofu is a dried food whose moisture content has been reduced to around 10% by freezing and drying, but it is usually rehydrated by hot water to absorb a large amount of moisture again, swell it, and then season and cook as appropriate. As a result, it was first made edible. In this way, frozen tofu can also be regarded as a variation of high-moisture foods, since it is a necessary condition for its use (edible) to contain a large amount of water when eaten. Furthermore, if we consider the texture of tofu as a food, excluding the amount of water it contains, so-called tofu has excellent smoothness, but on the other hand, it is only solid and strong, making it difficult to pick with human fingers. On the other hand, air-dried frozen tofu has sufficient strength (firmness) as a solid food, but if left in the air-dried state,
When placed on the human tongue, it has a coarse texture and tasteless taste that cannot be considered food. Frozen tofu and so-called tofu are both processed soybean foods that are rich in high-quality oil and fat, have good digestibility, and are nutritionally superior.
This is widely recognized in the fields of nutrition and medicine, and is becoming increasingly understood by general consumers. Despite this, consumption of these processed soybean products has not increased significantly. The main reason for this is that there are contradictory problems such as high moisture content during ingestion and an imbalance between texture and solid food strength. The contradictory problems mentioned above, namely, high water content during feeding;
and by resolving the imbalance between texture and strength and modifying the composition of tofu and frozen tofu, which are conventionally known only as culinary foods.
An object of the present invention is to provide a type of dried tofu that is directly edible, which has never been known before, and a method for producing the same. (Structure of the Invention) In the present invention according to the above object, the main component is soybean milk gel or tofu freeze-dried product, the freeze-dried product has a moisture range of 5 to 10% by weight, and has a main distribution.
It is characterized by having a dense porous structure with a pore diameter of 10 to 30 μm, and having a coating material adhered to the surface. In addition, the first step is to produce soymilk gel or tofu from soybeans, mold the resulting soymilk gel or tofu into a shape of any size, and quickly freeze the molded soymilk gel or tofu to reduce the temperature to -18 ℃ or below, followed by vacuum freeze-drying to reduce the moisture content to 5~5°C.
A second step of producing a freeze-dried product having a dense porous structure with a pore size of 10% by weight and a main distribution of pores of 10 to 30 μm, and coating the surface of the freeze-dried product with a coating material. It is characterized by Since the tofu snack according to the present invention is based on the same manufacturing method, it will be explained together with the manufacturing method. The method for producing tofu snacks according to the present invention basically includes two steps, as will be described in detail later. First, the first step is to produce a soybean milk gel solid having an arbitrary fixed shape, which has a dense and smooth texture, and has the strength (firmness) to withstand the second step operation. First, raw soybeans are soaked in water, crushed, steamed, and filtered to produce soybean milk. Calcium chloride, magnesium chloride, or calcium sulfate is added to this soymilk and stirred to cause a coagulation and flocculation reaction.
A soybean milk gel solid having an arbitrary fixed shape (hereinafter simply referred to as soybean milk gel) is produced by filling in a mold box, compressing and dehydrating, cooling by immersion in water, cutting into intermediate sizes, and molding. In the above first step, the process operations up to intermediate size cutting may be carried out using the usual process conditions for producing momen tofu or fresh tofu for frozen tofu. However, for the purpose of improving the structure of the freeze-dried product and preventing cracks in the second step, it is desirable to incorporate a small amount of carrageenan (a sulfated polysaccharide of red algae) in the soymilk coagulation and aggregation reaction. The appropriate concentration of carrageenan used here is 0.02% to 0.1% in soy milk. In addition, in order to make the final molding operation easier and smoother, in the compression dehydration process, the water content should be reduced to 90% or less, preferably 85%.
%. In the molding process, the size is, for example, 1 x 1 x 5 cm square. This size and shape are commercially available karinto, large candy, chocolate bars, biscuits,
This is an example of a size and shape comparable to that of a state-shaped kutsky or other sweets. Theoretically, the present invention can be used to arbitrarily set even larger shapes, but in order to proceed smoothly with the next second step, it is a practical condition that the maximum thickness is 2 cm or less. Become. Next, the second step is to freeze and dry the tofu gel. First, tofu gel is immersed in an aqueous carrageenan solution having a concentration of about 1% by weight for 15 to 30 minutes. On this occasion,
Depending on the food form of the end product, suitable sweeteners or flavoring substances are used in combination with carrageenan. Sweeteners used here include sucrose, glucose, sorbitol, malbitol, or cupping sugar.
A 10 to 20% by weight aqueous solution is suitable. Also, when using coffee as one of the seasoning substances,
A suitable solid content concentration in the aqueous solution is 1 to 2% by weight. In addition, in place of or in combination with carrageenan in the first step and this step, other suitable aqueous gum substances can be used as the structure improving material. The pretreated tofu gel is flash frozen using a liquid nitrogen freezing device. In this case, a minimum temperature of -40°C is sufficient, and lower temperatures are not particularly required. Because liquid nitrogen freezing is so-called instant freezing, it has the effect of making the ice crystals extremely fine and making the structure of frozen tofu dense and uniform.
As an inert gas, it has an antioxidant effect on processed foods. This can be understood from the fact that the cross section of the dried product exhibits a light yellowish white color that is denser and cleaner than tofu, as usual. Moreover, instead of liquid nitrogen freezing, a quick freezing method using an air freezing method (including air cutoff freezing in an air blast method) using a mechanical freezing device using Freon or ammonia refrigerant may be used. Although rapid freezing by mechanical freezing cannot form ice crystals as fine as liquid nitrogen, it has the advantage of producing a dense and smooth edible structure. In the past, rapid freezing at -20°C was not considered possible in the production of frozen tofu due to the necessity of mechanical dehydration after freezing. The fine ice crystals associated with rapid freezing reduce the drying rate, especially at the end of the drying process, and are therefore beneficial in controlling the small amount of moisture retention in the finished product. In short, the freezing conditions at this time only need to be freezing speed and freezing temperature conditions as a means of forming ice crystals as fine as possible. By the way, rapid freezing in food freezing refers to the "maximum ice crystal formation zone (-1 to -5℃)".
It is generally accepted that "freezing is such that the product temperature easily reaches -18°C (equilibrium temperature)". Specifically, it is desirable that the maximum ice crystal formation zone passage time be within about 11 hours. In addition,
Although the still air freezing method is not as aggressive as the liquid nitrogen freezing method, it is an effective method for preventing oxidation of tofu. Then, the frozen tofu gel that has been quickly frozen is immediately vacuum freeze-dried in a vacuum freeze-drying apparatus by a conventional method. Generally, in commercial vacuum freeze-drying equipment, the final moisture control system for dried products is currently undeveloped. Therefore, the finished state of drying is determined based on the product temperature and time curve, and the dried product according to the present invention is finished in a moisture range of 5% to 10%. Absolutely dried food takes saliva away from the mouth, directly impairing its edibility. It is difficult to control the moisture content in the freeze-drying equipment, and when the moisture content of the dried tofu gel (hereinafter simply referred to as dried tofu) reaches an absolute dry state (2% to 3% or less), add an appropriate amount of water. Dried tofu is stored in an airtight container placed at the bottom of the container, and the moisture content is adjusted through natural humidification. Vacuum freeze-drying is a necessary and effective means for drying frozen products of fine ice crystals that are difficult to dry using other methods. Further, since the drying is carried out under reduced pressure and at a low temperature, there is an advantage that oxidation of the dried material is prevented.
Conventionally, in the freezing and drying of frozen tofu production,
Frozen tofu Even attempts to apply vacuum freeze-drying to the product were recognized as pointless. It is thought that the process operations of adjusting the finished moisture, non-oxidative freezing, use of carrageenan, and reducing the size of the processed product have a synergistic effect on preventing cracks in the dried finished product. The dried tofu obtained in the above manner has a denser porous structure than frozen tofu. Frozen tofu usually has a coarse porous structure with a pore diameter of about 30 to 500 μm, but dried tofu obtained in the above process has a porous structure with a main distribution of pore diameters of 10 to 30 μm. Of course, there are some with pore diameters larger than 30 μm, but most have pore diameters in the range of 10 to 30 μm. Next, coat the dried tofu. The significance of this is that it improves its edibility and preservability while improving its appearance as a snack food or confectionery. The dried tofu obtained in the above step is coated with, for example, thiokolate for confectionery as a coating material. That is, dried tofu gel is immersed in thiocolate melted on a hot water bath, coated, and then placed on an aluminum butt or a suitable drying stand to solidify the thiokolate at room temperature of 0 to 20°C and peeled off. As a coating material, in addition to Chiyocolate, a coating material such as caramel can also be used. Through the above first and second steps, tofu snacks are completed. As is already clear, the composition of this product is a food whose main ingredients are chemical components equivalent to the solid content of momen tofu or frozen tofu. (Example) Example 1 Soybeans soaked in water for 16 hours at a water temperature of 15 to 18°C (2.3 times the weight of the raw soybeans) were further added with water 8.7 times the weight of the raw soybeans, and ground.
After boiling for a minute, it was filtered to obtain hot soy milk. temperature 70
At ℃, calcium chloride and calcium chloride were added to the heated soymilk so that the concentrations in the soymilk were 0.2% and 0.02%, respectively.
and carrageenan in various aqueous solutions were added and stirred to cause a coagulation and aggregation reaction. After removing the excess separated liquid, the reacted solid content was placed in a mold box, and the load was gradually increased to press and dehydrate the mold to form tofu. Tofu obtained by separating the mold box, cutting, and soaking in cold water (8 x 12 x 4 cm)
The moisture content of the horn was 85%. Next, the tofu was cut into pieces of 1 x 1 x 4 cm squares, and immersed in a sufficient amount of 10% coupling sugar aqueous solution for 30 minutes at room temperature. This pretreated shredded tofu was placed in a liquid nitrogen freezing device and flash frozen. Although the nitrogen atmosphere temperature temporarily dropped to -80℃,
The lower limit was -40°C, and the temperature was kept at -40°C for 1 hour to ensure complete freezing. Subsequently, it was transferred to a vacuum freeze-drying apparatus whose shelf temperature had been previously cooled to -30 to -40°C, and the vacuum freezing apparatus was immediately started.
Approximately 1 hour after the start of operation, a sufficient degree of vacuum (approximately 1×10 ^-1
mbar), the shelf temperature (set temperature) is increased stepwise (0 to 30°C) to accelerate drying,
After 24 hours, vacuum freeze-drying was completed. The maximum degree of vacuum during this period is 8×10 ^-2 mbar (8Pa), and the maximum product temperature is 20
It was between 30℃ and 30℃. The dried product obtained here was almost completely dry, so it was transferred to another airtight container.
Warm water was placed at the bottom of the vessel, and the mixture was naturally humidified for about 5 hours, and finally dried tofu pieces with a water content of about 8% and a pale yellowish white color were obtained. Finally, household thiokolate with a melting point of about 32°C was melted in a hot water bath, and the dried tofu pieces were dipped into this, the entire surface was coated, pulled out, and arranged on a smooth aluminum part. Store this in a home freezer for about 20 minutes, wait until the temperature has dropped to 10 to 20°C and the tyokolate has solidified sufficiently, and then take it out. By slightly bending the bottom of the vat, it can be easily peeled off. , the object of the present invention was obtained. Example 2 Fresh tofu processed for frozen tofu production (58×74×
18mm square, moisture 81%), cut into small pieces, approximately 58 x 9 x 18 mm
The square size was approximately 29 x 9 x 9 mm. After immersing this in an aqueous solution containing 10% sucrose and 1% carrageenan for 30 minutes, part of it was frozen with liquid nitrogen as in Example 1, and the remaining part was stored in a -20°C walk-in freezer. It was then frozen and stored overnight (16 hours). These frozen tofu pieces were vacuum freeze-dried under the same conditions as in Example 1. However, in this case, quality
Judging from the time curve, the drying process was terminated at a rather modest stage, the pressure inside the vacuum freeze-drying apparatus was returned to atmospheric pressure, and the vacuum freeze-drying apparatus was kept at a low temperature in a closed state, and after about 6 hours, the dried product was transported out. The dried product was pale yellowish white and had a moisture content of 8 to 10%. Finally, thiokolate for confectionery use having a melting point of about 36° C. was melted in a water bath, and then a thiokolate coating was applied in the same process as in Example 1 to obtain the final target product. Example 3 Fresh tofu processed for frozen tofu production was cut into sticks of about 9 x 9 x 58 mm. this,
Commercial instant coffee (freeze-dried product) 1.5
% weight, sucrose 2% weight, and glucose 2% weight for 30 minutes at room temperature. Arrange them on aluminum trays, wrap them in saran wrap to prevent direct exposure to outside air, and store them in an air-blast type quick-freezing chamber (room temperature -22°C).
℃) and frozen overnight (16 hours). Then, vacuum freeze-drying was carried out under the same conditions as in Examples 1 and 2 to obtain a brown stick-like dried product. Furthermore, the tofu snacks obtained in each of the above examples were
When stored in a refrigerator at 10°C, no change in quality was observed for at least 3 months. The product of the present invention obtained as described above was given to 10 confectioners, 5 frozen tofu manufacturers, and the general public.
Table 1 shows the responses of 10 people (5 people each for Example 3) who sampled each sample individually.
It seems like.

[Table] (Effects of the Invention) The tofu snack according to the present invention has the following remarkable effects. This product meets a wide range of tastes among men and women of all ages in terms of fragrance, odor, taste, and texture. In particular, whereas so-called dry frozen tofu has a rough and stiff texture derived from its spongy structure, this product has a moisture content of 5% to 10% and has a small apparent specific gravity and a dense porous structure. Since it is made from eggplant, it does not absorb saliva in the mouth, does not feel so-called rough, has a moderate texture, and does not leave any residue on the tongue. This product has almost no soy odor and can be eaten without any objection. It has a longer shelf life and shelf life than regular frozen tofu. Because the ingredients equivalent to tofu or frozen tofu are preserved, it has extremely high nutritional value. Moreover, since it is coated with thiokolate or the like, it is effective in retaining the moisture content in the inner layer and stabilizing the fats and oils that are normally easily oxidized, and its palatability is maintained for a long time. It has the appropriate strength as a confectionery or snack food. That is, it has sufficient direct edibility. Further, the following remarkable effects are recognized in the manufacturing method of the present invention. The manufacturing process is simple and mass production or small quantity production is possible. In particular, the freeze-denaturation process for frozen tofu takes about 20 days, and the processes after the freezing process are also complex and require a considerable amount of energy. However, in the present invention, there is no energy-intensive process other than vacuum freeze-drying, and the process can be completed in a short period of time. We can supply products at low prices. By performing vacuum freeze-drying, oxidation of non-dried products can be prevented and high quality tofu snacks can be provided. In particular, vacuum drying can be performed without causing cracks in the dried product by adjusting the finished moisture content, non-oxidative freezing, using carrageenan, reducing the size of the processed product, etc. Soaking unfrozen tofu in a sugar solution is effective in suppressing the freeze denaturation of soybean proteins that may occur, and also contributes to maintaining the humidity of dried finished products and adding flavor as a sweetener. The use of carrageenan not only contributes to improving the texture of finished products, but also effectively prevents cracking in vacuum freeze-dried products. This is thought to be due to a chemical reaction between soybean protein and carrageenan, a sulfated polysaccharide. Since liquid nitrogen freezing is so-called flash freezing, it has the effect of making the ice crystals extremely fine and making the structure of frozen tofu dense and uniform, and as an inert gas, it has the effect of preventing oxidation of processed foods. In addition, rapid freezing by mechanical freezing does not produce as fine cryogenic crystals as liquid nitrogen, but it has the advantage of producing a dense and smooth edible structure. The fine ice crystals that result from rapid freezing reduce the drying rate, especially at the end of the drying process, and are therefore beneficial in controlling the small amount of moisture retained in the finished product. Although the present invention has been variously explained above with reference to preferred embodiments, the present invention is not limited to these embodiments, and it goes without saying that many modifications can be made without departing from the spirit of the invention. It is.

Claims (1)

[Scope of Claims] 1. A dense gel whose main component is soybean milk gel or tofu freeze-dried product, the freeze-dried product has a moisture range of 5 to 10% by weight, and has a main distribution of pore diameters of 10 to 30 μm. Tofu snacks have a porous structure with a coating material attached to the surface. 2. The first step of producing soymilk gel or tofu from soybeans and molding the obtained soymilk gel or tofu into a shape of any size, and quickly freezing the molded soymilk gel or tofu to reduce the product temperature to -18°C. and then vacuum freeze-drying to achieve a moisture content of 5 to 10% by weight and a main distribution of
A method for producing tofu snacks, comprising the steps of: producing a freeze-dried product having a dense porous structure with a pore size of 10 to 30 μm; and coating the surface of the freeze-dried product with a coating material. . 3. The method for producing tofu snacks according to claim 2, characterized in that the thickness of the molded product in the first step is 20 mm or less. 4. The method for producing tofu snacks according to claim 2 or 3, characterized in that in the tofu coagulation and aggregation reaction in the first step, carrageenan is blended into the aggregation liquid. 5. Claims 2, 3, or 5, wherein the second step includes a step of immersing the shaped soymilk gel or tofu in an aqueous seasoning solution such as an aqueous carrageenan solution or an aqueous sweetener solution, or 4. The method for producing tofu snacks according to item 4. 6 Claim 2, characterized in that the quick freezing in the second step is performed using liquid nitrogen;
The method for producing tofu snacks according to item 3, 4, or 5. 7 Claims 2 and 3, characterized in that the quick freezing in the second step is performed by a mechanical freezing device using Freon or ammonia refrigerant.
5. The method for producing tofu snacks according to item 4, item 5, or item 5.