预处理及解冻方法对马铃薯冻融品质的影响

Effect of Pretreatment and Thawing Method on Freezing and Thawing Quality of Potato

目的 提高马铃薯冻融后的品质,为PEF预处理在蔬菜冷冻领域的应用提供理论依据。方法 探讨预处理方法(脉冲电场、热处理)和解冻方法(常温解冻、水里解冻、冰箱解冻)对马铃薯冷冻–解冻过程及品质的影响,分析冰晶成核温度、融化温度、汁液损失比、色泽、硬度等理化指标,并通过低场核磁共振仪分析冻融后样品不同状态下水分间的迁移情况。结果 热烫和高压脉冲电场(Pulsed Electric Field,简称PEF)预处理均可显著降低冷冻时间、提高冰晶成核温度。PEF预处理样品在最大冰晶体形成带的滞留时间相较于对照组样品降低了26.3%。在不同解冻方式下,PEF预处理和热烫预处理均可降低马铃薯冻融后的汁液损失。在常温下解冻,对照组、热烫组、PEF预处理组的汁液损失率分别为24.12%、17.39%、15.53%。PEF预处理和热烫预处理可减缓食品在冻融过程中的颜色和硬度的变化进程。结论 PEF预处理可以改善冻融后马铃薯的品质,可为PEF在果蔬冷冻领域的应用提供理论参考。

The work aims to improve the quality of potato after freezing and thawing and provide theoretical basis for the application of PEF pretreatment in vegetable freezing.The effect of pretreatment methods(pulse electric field and blanching)and thawing methods(room temperature thawing,water thawing and refrigerator thawing)on potato freezing-thawing process and quality was discussed,the physicochemical indicators such as ice crystal nucleation temperature,melting temperature,water loss ratio,color,hardness,etc.were analyzed and the migration of water at different states of samples after freezing and thawing was analyzed by low field nuclear magnetic resonance analyzer.Blanching and PEF(Pulsed Electric Field)pretreatment could significantly reduce the freezing time and increase the ice crystal nucleation temperature.Moreover,the retention time of PEF pretreated samples in the maximum ice crystal formation zone was 26.3%lower than that of the control group.PEF pretreatment and blanching pretreatment could both reduce the water loss of potato after different thawing methods.For room temperature thawing,the water loss ratio of treated, blanching pretreated and PEF pretreated samples were 24.12%, 17.39% and 15.53% respectively. At the sametime, PEF pretreatment and blanching pretreatment could also reduce the color change and hardness change of food duringfreezing and thawing. PEF pretreatment can improve the quality of potato after freezing and thawing, which providestheoretical reference for the application of PEF in the field of vegetable freezing.