To systematically investigate the effects of corn starches with different amylose content, including normal corn starch, high-amylose corn starch and waxy corn starch, on the freeze-thaw stability of konjac gels.
The texture characteristics, water separation rate and water retention rate of the samples were determined. The water distribution characteristics were analyzed in combination with low-field nuclear magnetic resonance technology, and the microstructure and crystalline structure analyses were carried out to reveal the structure-water-performance relationship of the composite gel.
The addition of corn starch could all improve the freeze-thaw stability of konjac gel. Among them, the 5% waxy corn starch system performed the best. After 5 freeze-thaw cycles, the water separation rate was only 5.58%, the water retention rate remained at 89.94%, the proportion of retained water in the system was maintained at 96.40%, and the proportion of free water was less than 1.20%. Moreover, the variation range of hardness and chewiness was the smallest. The results of scanning electron microscopy showed that the waxy corn starch system still maintained a continuous and uniform porous network structure before and after freeze-thaw, with only slight pore expansion. The results of the crystalline structure showed that its crystallinity changed the least, and the low-temperature regeneration was significantly inhibited. The appearance remained intact and the color was bright.
The highly branched amylopectin structure in waxy corn starch can restrict the regular arrangement of recrystallization and molecular chains. Meanwhile, the abundant hydroxyl groups on its molecules can form hydrogen bonds with konjac and water molecules, maintaining a stable hydration state and reducing the freedom of water migration. This effectively inhibits water migration, phase separation and structural damage induced by freeze-thaw cycles, significantly improving the freeze-thaw stability of konjac gel.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |