寒地冬小麦冰结构蛋白对冷冻豆腐品质及蛋白性质的抗冻保护作用

Antifreeze Protective Effect of Winter Wheat Ice Structural Proteins on the Quality and Protein Properties of Frozen Tofu

冷冻豆腐经常出现质地粗糙、孔径不均、甚至断面等品质问题。该研究采用冰球结合磷酸盐缓冲液法提取寒地冬小麦冰结构蛋白(Winter Wheat Ice Structural Proteins,WISPs),经检测热滞性为0.46℃,其溶液的冰晶形态小、数量多,具有一定的抗冻活性。在不同添加量WISPs各组冷冻豆腐中,当添加质量分数为1.00%时,其持水率、复水性、耐煮性及弹性、拉伸性较对照组分别提高了114.17%、57.42%、56.25%、21.52%、23.71%,硬度、剪切力降低了24.83%、23.75%;结合水、半结合水、不易流动水含量增加了133.77%、131.78%、26.41%;横截面光滑细腻,蜂窝均匀,孔径大小适中。此时冷冻豆腐蛋白游离疏基含量较对照组增加了37.50%,二硫键含量减小了29.79%;对照和0.25%组中90 ku以上的组分全部降解;除0.75%和1.00%组外,其余各组的BS亚基中低分子量组分降解;各组中AS、BS亚基含量均少于1.00%组,说明1.00%组的蛋白组分最稳定。WISPs作为抗冻保护剂,改善了冷冻豆腐的品质和蛋白质结构特性,对其具有抗冻保护作用,为抗冻蛋白在冷冻食品中的应用提供了理论基础。

Frozen tofu is often associated with quality issues,such as coarse texture,inconsistent pore sizes,and even broken sections.Herein,ice balls were combined with phosphate buffer solution(PBS)to extract winter wheat ice structural proteins(WISPs).Based on the analysis,its thermal hysteresis activity(THA)was 0.46℃.The ice crystals in the solution were small and numerous,and exhibited a certain anti-freezing activity.When 1.00%of WISP was added to frozen tofu,the water holding capacity,rehydration capacity,cooking resistance,elasticity,and stretchability increased by 114.17%,57.42%,56.25%,21.52%,and 23.71%,respectively,compared with those of the control,while the firmness and shear force decreased by 24.83%and 23.75%,respectively.The content of bound water,semi-bound water,and non-flowing water increased by 133.77%,131.78%,and 26.41%,respectively.The cross section was smooth and delicate,the honeycomb was uniform,and the pore sizes were moderate.Compared with the control,the free sulfhydryl group content of the frozen tofu protein increased by 37.50%and the content of disulfide bonds decreased by 29.79%.All components above 90 ku in the control group and 0.25%group had degraded.Except for the 0.75%and 1.00%groups,the low molecular weight components of the BS subunits in other groups were degraded.The contents of the AS and BS subunits in each group were lower than those in the 1.00%group,indicating that the protein components in the 1.00%group were the most stable.As an antifreeze protective agent,WISPs improved the quality and characteristics of the protein structure of frozen tofu,and exhibited an antifreeze protective effect.This result provides a theoretical basis for the application of antifreeze protein in frozen food.