JPH01165333A - Freezing of food produced from thermally denaturated protein - Google Patents

Abstract

PURPOSE:To prevent the lowering of the quality of a food containing thermally denaturated protein even after preservation over a long period, by freezing the food after cooling to a temperature slightly above the freezing point. CONSTITUTION:A food containing thermally denaturated protein, e.g., pudding containing albumen, bean curd containing soybean protein or KAMABOKO (boiled fish paste) containing fish meat protein is slowly cooled to a temperature slightly above the freezing point to uniformize the temperature throughout the food. The cooled food is frozen by quick cooling and the cooling is continued to obtain a frozen food at a stroke. The frozen food is cooled to a prescribed preservation temperature, i.e. about -5--25 deg.C.

Description

[Detailed Description of the Invention] A. Industrial Application Field The present invention is based on the invention, which is made by freezing for long-term storage.
The present invention relates to a method for freezing foods using heat-denatured proteins, such as pudding using egg white, tofu using soybean protein, and protein-free fish cakes, which do not deteriorate in quality even if thawed later.

Conventional technology Conventionally, all frozen foods, not just foods using heat-denatured proteins, have been stored at room temperature to the frozen storage temperature of approximately -25°C to -3°C.
It was cooled steadily to 0°C.

C. The problem that the invention aims to solve: When the cooling rate is high, the ice crystals become finer and the structure of the protein is less likely to be destroyed, but the temperature difference between the inside and outside becomes large, causing cracks due to expansion and contraction. There is a drawback. In other words, in the process of freezing, the surface layer first freezes and the freezing progresses to the inside, so when the outside expands due to freezing and that pressure is applied to the unfrozen inside, internal strain occurs due to the residual stress. Eventually, cracks will appear. On the other hand, if the cooling rate is slowed down, it will take time for the freezing to progress to the inside, and the ice crystals will become too large, leading to tissue destruction and becoming porous and spongy, with a poor texture and poor taste when thawed. There was a detriment to it.

As described above, both rapid cooling and slow cooling have the above-mentioned drawbacks, and therefore frozen foods have a reputation for being unpalatable, and the commercial value of foods using heat-denatured proteins in particular has been severely reduced.

2. Means for Solving the Problems The present invention takes into account the drawbacks of frozen foods that use heat-denatured proteins. In order to prevent the food from being damaged, this freezing method has been completed after various experiments.When freezing food containing heat-denatured proteins, the freezing point of the food is determined in advance. The purpose is to uniformly cool the inside and outside to the temperature immediately before the temperature.

(e) When freezing, the inside and outside are uniformly cooled in advance to a temperature on the verge of freezing, so even when rapidly cooled, there is only a small temperature difference between the surface layer and the center, and even fine ice crystals form. Since countless amounts of are produced, tissue destruction is prevented and quality is maintained even after thawing, making it possible to obtain ideal frozen foods using heat-denatured proteins.

EXAMPLE Hereinafter, an example in which the present invention was implemented using a pudding having the following raw material composition will be explained based on the drawings.

Milk 50.0% Sugar 15.0% Kinjirushi 25.0% Flavoring 0.1% Water 9.9% Total too, 0% Heat and coagulate the above pudding ingredients in a container at a temperature of 60°C or higher. , store it in a container in a freezing/refrigerating room, and as shown in Figure 1, the freezing point of pudding is reached from room temperature.
It is slowly cooled to just below 1.7°C, kept at a temperature just before reaching the freezing point, and left for 2 hours to equalize the temperature inside and outside.

Next, the so-called critical temperature range from around the freezing point of -1.7°C to around the freezing point of around -5°C is rapidly cooled using, for example, brine, which is a secondary refrigerant, and the temperature drops rapidly to below the critical temperature range in about 10 minutes. .

As a result, many fine ice crystal nuclei are generated both inside and outside the pudding, and fine ice crystals are generated by the growth of the ice crystal nuclei.

Since the pudding before quenching has a uniform low temperature distribution inside and outside, there is almost no difference in temperature between the surface layer and the center during the quenching process, and no cracks occur.

Further, rapid cooling is continued to cool down to -25°C, which is the freezing storage temperature. That is, the freezing point of egg white is as low as 10.45°C, and the freezing precipitation rate due to rapid cooling in the above-mentioned limit temperature range is approximately 90%.
Therefore, when cooled in about 20 minutes from around -5°C to the freezing storage temperature around -25°C, the remaining components will form fine ice crystals, and the growth of the already formed ice crystals will be inhibited, resulting in fine ice crystals. It is a frozen product with ice crystals, and even after thawing, you can obtain a pudding with the same quality as before freezing.

Furthermore, since the freezing method is performed by rapid cooling as described above, processing time is shortened and the operating rate of the freezing/refrigerating room is improved, thereby contributing to improved productivity.

In this example, a method for freezing pudding, which is a food product using heat-denatured egg whites, has been explained. However, the raw material composition of the pudding is merely an example, and can be changed as appropriate depending on the desired taste. . The freezing method of the present invention is also suitable for freezing processed foods such as tofu and kamaboko, as long as they use heat-denatured proteins.

G. As described in detail, according to the present invention, a food containing heat-denatured protein is maintained just before its freezing point to equalize the internal and external temperature distribution, and then rapidly cooled from its freezing point. By freezing the food first, followed by rapid cooling, and then freezing all at once, it is possible to produce frozen foods that do not have cracks, have a fine ice crystal structure, and do not lose quality even when thawed after long-term storage. Therefore, there are great benefits to food processing.

[Brief explanation of the drawing]

FIG. 1 is a pudding freezing curve diagram showing an example of the present invention. A%A'...freezing point of pudding, B...freezing point of pudding,
C...Frozen storage temperature of pudding, Hlh...Time, L...
Limit temperature zone, T...Temperature patent applicant Sakaeya Dairy Co., Ltd.

Claims (1)

[Claims] A method for freezing foods using heat-denatured proteins, which is characterized in that, before freezing the food containing heat-denatured proteins, the inside and outside of the food are uniformly cooled to a temperature just before the freezing point of the food.