抗坏血酸浸渍后草莓中天然叶酸稳定性的变化

Changes in the Stability of Folate in Strawberries after Ascorbic Acid Impregnation

为研究抗坏血酸(Ascorbic Acid,AsA)浸渍后草莓中叶酸稳定性的变化,该研究采用真空(0.09 MPa)和常压两种方式浸渍AsA,对比浸渍速率以及浸渍后中天然叶酸的稳定性及草莓的新鲜度。同时探讨真空浸渍AsA的草莓在8 d冷藏过程中,天然叶酸的含量及质构的变化。结果表明,真空浸渍AsA的传质速率更快(k2=0.01),浓度更高(1.24 mg/g)。草莓中总叶酸含量为100~128μg/100 g,主要叶酸种类为5-甲基四氢叶酸、四氢叶酸、5,10-亚甲基四氢叶酸及叶酸降解产物或合成底物对氨基苯甲酸。草莓经8 d冷藏后,真空浸渍组和对照组的四氢叶酸分别下降了7.70%和42.51%,对氨基苯甲酸分别上升了57.13%和77.89%,5,10-亚甲基四氢叶酸均未出现显著性变化(p>0.05),5-甲基四氢叶酸在第4天分别上升了24.47%和12.67%。质构结果表明,第8天时,真空浸渍组硬度(92.60 N)明显高于对照组(57.20 N)。因此,真空浸渍AsA处理可以抑制四氢叶酸降解(p<0.05),从而提高叶酸在冷藏中的稳定性,保护草莓的质地。该研究为提高草莓叶酸稳定性提供了理论依据和参考。

Ascorbic acid(AsA)was impregnated in strawberries under vacuum(0.09 MPa)and atmospheric pressure to compare the impregnation rate and stability of folate and freshness of strawberries after impregnation.The texture and folate content in strawberries impregnated with AsA during a 8-day cold storage were also investigated.The results indicated that vacuum impregnation resulted in a faster mass transfer rate(k2=0.01)with a higher AsA concentration(1.24 mg/g).The folate content in strawberries was 100~128μg/100 g;the main types of folate were 5-methyltetrahydrofolate,tetrahydrofolate,5,10-methylenetetrahydrofolate,and folate degradation products or synthetic substrates para-aminobenzoic acid.After 8 days of refrigeration,the tetrahydrofolate content decreased by 7.70%and 42.51%in the vacuum impregnation and control groups,respectively.The para-aminobenzoic acid content in the vacuum impregnation and control groups increased by 57.13%and 77.89%,respectively.No significant change was observed in the 5~10 methylenetetrahydrofolate content(p>0.05).The 5-methyltetrahydrofolate content in the vacuum impregnation and control groups increased by 24.47%and 12.67%on day 4,respectively.Microstructure analysis indicated that after 8 days of refrigeration,hardness of strawberries in the vacuum impregnation group(92.60 N)was significantly higher than that in the control group(57.20 N).Therefore,vacuum AsA impregnation inhibited the degradation of tetrahydrofolate(p<0.05),thereby enhancing the stability of folate in cold storage and protecting the texture of strawberries.This study provides a theoretical basis and reference for improving the stability of folate in strawberries.