不同前处理的冻融荔枝果壳色泽和微观结构比较分析

Comparison of Effects of Different Pretreatments on Color and Microstructure of Frozen-thawed Litchi Pericarp

摘要:

该研究探讨了护色保脆前处理对冻融后的荔枝果壳酚酶氧化、细胞完整性及褐变抑制等品质特性的影响。结果显示，“8% C6H8O7+0.5% Vc+1% CaCl2”前处理组的色泽与新鲜荔枝最为接近，与对照组相比，其相对电解质渗出率和汁液流失率分别降低18.71%和0.92%，硬度保留率提高了14.17%，多酚氧化酶和过氧化物酶的残余酶活力分别降低158.18%和342.14%，多酚、花色苷含量、抗氧化能力保留率分别提高了9.79%、27.11%和10.21%。柠檬酸的护色效果较Vc佳，CaCl2在保脆中起着关键作用，三个护色保脆试剂之间具有协同增效的作用，其中，Vc需在氯化钙存在时，才能显现出对细胞完整性的保护效果；0.5% Vc（m/V）与柠檬酸、氯化钙之间具有协同增效护色钝酶、保护质构的效果；柠檬酸浓度越高对硬度的保护效果越好。总而言之，“8% C6H8O7+0.5% Vc+1% CaCl2”前处理组可作为速冻荔枝的适宜护色保脆前处理模式。该研究结果可以为荔枝保鲜加工提供技术支撑。

Abstract:

The effects of color and crispness preservation pretreatments on frozen-thawed litchi pericarp were investigated in this study, including the effects on phenolase oxidation, cell integrity, browning, and other quality attributes. The results show that the color and shine of the litchi pretreated with 8% C6H8O7 + 0.5% Vc + 1% CaCl2 closely resemble those of fresh litchi. Compared to those of the control group, the relative electrolyte exudation rate and the juice loss rate of litchi after this pretreatment are decreased by 18.71 and 0.92%, respectively. In addition, the hardness retention rate is increased by 14.17%, while the residual enzyme activities of polyphenol oxidase and peroxidase are decreased by 158.18 and 342.14%, respectively. Meanwhile, the contents of polyphenols and anthocyanins and the antioxidant capacity retention rate increased by 9.79, 27.11, and 10.21%, respectively. Citric acid is found to be more effective in color preservation than Vc, while CaCl2 plays a critical role in maintaining crispness. Synergistic effects are noted among the three color- and crispness-preserving agents. In particular, the protective effects of Vc on cell integrity are observed only in the presence of CaCl2. The combination of 0.5% (m/V) Vc with citric acid and CaCl2 synergistically show enhanced color preservation and texture protection against enzymes. Hardness is better preserved at higher citric acid concentrations. In conclusion, pretreatment with 8% C6H8O7 + 0.5% Vc + 1% CaCl2 can be considered as a suitable solution for color and crispness preservation of frozen litchi. The results of this study can provide technical support for the preservation and processing of litchi.