TEXTURE AND STRUCTURE OF HIGH-PRESSURE-FROZEN FOOD GELS.

为了确定高压冷冻对质量的影响，由蛋白质组成的凝胶（豆腐、蛋羹和明胶凝胶）和多糖凝胶在100 MPa（冰I）、200 MPa（冰I）、200 MPa（冰I）和200 MPa（冰I）下，（液相）、340 MPa（冰III）、400、500、600 MPa（冰V）或700 MIPa（冰VI）。在降低到大气压后，将凝胶储存在-30 ° C，然后在20 ° C解冻。然后将质地和结构（低温-SEM观察）与在大气压（0.1 MPa）下冷冻（-20 ° C、-30 ° C或-80 ° C）的凝胶进行比较。在没有蔗糖的凝胶，冷冻在0.1，100，600和700 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（除冰I）在200 - 400 MPa下冷冻时，冷冻凝胶的质量与在0.1和100 MPa下冷冻的凝胶（冰I）相比得到改善。然而，质量不同于解冻凝胶。随着蔗糖用量的增加，凝胶的外观、质构和结构均得到改善。为了确定冰在减压过程中的相变，在相同的高压下解冻高压冷冻凝胶。此后，压力降低。在200 - 500 MPa下冷冻的凝胶的质地与原始凝胶相同。这表明相变（从冰VI到冰V到冰III到液体到冰I）发生在减压（-20 ° C）期间，或在冰箱中储存期间。然而，当凝胶在200-400 MPa和-20 ℃下加压时，凝胶不冻结（过冷），而减压后，凝胶迅速冻结。因此，在200-400 MPa的高压冷冻是有效的，在提高所有冷冻凝胶的质量。

To determine the effect of high-pressure-freezing on quality, gels composed of protein (tofu, egg custard and gelatin gel) and gels of polysaccharides (agar, konjac, carrageenan-locust bean gum, curdlan and gellan gums) were frozen at 100 MPa (ice I), 200 MPa (liquid phase), 340 MPa (ice III), 400, 500, 600 MPa (ice V) or 700 MIPa (ice VI) at ca. -20ﾟC.After reducing to atmospheric pressure, gels were stored at -30ﾟC then thawed at 20ﾟC.Texture and structure (cryo-SEM observation) were then compared with gels frozen (-20ﾟC, -30ﾟC or -80ﾟC) at atmospheric pressure (0.1 MPa). In gels without sucrose, frozen at 0.1, 100, 600 and 700 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 compared to gels frozen at 0.1 and 100 MPa (ice I). However, quality differed from unfrozen gels. With the increase of sucrose, appearance, texture and structure of all gels improved. To determine phase transition of ices during depressurization, high-pressure-frozen gels were thawed at the same high pressure. Aferwards, pressure was reduced. Texture of gels frozen at 200 - 500 MPa was the same as original gels. This suggested that phase transitions (from ice VI to iceV to ice III to liquid to ice I) occurred during reduction of pressure (-20ﾟC), or during storage in a freezer. However, when gels were pressurized at 200-400 MPa and -20ﾟC, the gels did not freeze (supercooling), while after depressurization, the gels froze quickly. Thus, high-pressure-freezing at 200-400 MPa was effective in improving the quality of all frozen gels.