BEHAVIOR OF WATER AND ICE IN FOOD UNDER HIGH- PRESSURE

为了确定高压冷冻对冷冻凝胶质量的影响，将由蛋白质组成的凝胶（豆腐和蛋羹凝胶）和多糖组成的凝胶（琼脂、海藻酸、角叉菜胶-刺槐豆胶、可得然胶和结冷胶）在100 ~ 686 MPa下加压，在约100 ~ 686 MPa下加压。-18℃至-20℃。减压至大气压后，将凝胶在-30℃下储存，然后在20℃下解冻。然后将其质地和结构（低温SEM观察）与在大气压（0.1 MPa）下冷冻（-20℃、-30℃或-80℃）的凝胶进行比较。在没有蔗糖的凝胶，冷冻在0.1，100，600和686 MPa，质地和结构显着不同，从原来的凝胶。另一方面，当所有凝胶（除了DAPRAAC）在200 - 400 MPa下冷冻时，冷冻凝胶的质量得到改善。随着蔗糖添加量的增加，凝胶的外观、质地和结构都有所改善。为了确定加压期间冰的相变，确定温度。当凝胶在200 ~ 400 MPa和-20℃下加压时，凝胶不冻结（过冷），但减压后，凝胶迅速冻结。冻融耐受性因所检测的凝胶种类而异。它们被分为三种类型：在冷冻过程中变硬的凝胶（豆腐，豆腐），变软的凝胶（琼脂，κ-卡拉胶，未取代的形式-结冷胶凝胶），和没有变化的凝胶（可得兰，取代的形式-结冷胶，ι-卡拉胶凝胶）。最后，在200 - 400 MPa的压力转移冷冻被认为是有效的，在提高所有的冷冻凝胶的质量。

To determine the effect of high-pressure-freezing on the quality of frozen gels, gels composed of protein (tofu and egg custard gel) and gels of polysaccharides (agar, konjac, carrageenan-locust bean gum, curdlan and gellan gums) were pressurized at 100 〜686 MPa at ca. -18℃ 〜 -20℃. After reducing to atmospheric pressure, gels were stored at -30℃ then thawed at 20℃. Texture and structure (cryo-SEM observation) were then compared with gels frozen (-20℃, -30℃ or -80℃) at atmospheric pressure (0.1 MPa). In gels without sucrose, frozen at 0.1, 100, 600 and 686 MPa, texture and structure differed significantly from original gels. On the other hand, when all gels (except konjac) were frozen at 200 - 400 MPa, the quality of frozen gels improved. With an increase of sucrose, the appearance, texture and structure of all gels improved. To determine the phase transition of ices during pressurization, temperatures were determined. When gels were pressurized at 200 〜 400 MPa and -20℃, the gels did not freeze (supercooled), but after depressurization, the gels froze quickly. The freeze-thaw tolerance differed with the kinds of gels being examined. They were classified in three types : gels which became hard during freezing (tofu, konjac), the gels which became soft (agar, kappa-carrageenan, unsubstituted form-gellan gum gels), and the gels which did not change (curdlan, substituted form-gellan gum, iota-carrageenan gels). Finally, pressure-shift-freezing at 200 〜 400 MPa was found to be effective in improving the quality of all frozen gels.