中温联合二甲基二碳酸盐对荔枝原汁品质的影响

Effects of Mild Heat Combined with Dimethyl Dicarbonate on the Qualityof Litchi Juice

该研究比较了二甲基二碳酸盐(Dimethyl Dicarbonate,DMDC)、中温及两者联合处理对荔枝原汁微生物及理化指标的影响。结果表明:荔枝原汁经DMDC或中温单独处理灭菌效果较差,联合处理组残留微生物最少,菌落总数、乳酸菌分别为0.41、0.36 lg CFU/mL,酵母菌和霉菌未检出;与新鲜荔枝汁相比,DMDC处理对荔枝原汁品质无影响,中温及联合处理组抗坏血酸和色泽无明显变化,总酚(总黄酮)分别增加了40.16%(7.16%)、38.01%(4.35%);铁离子还原能力(清除DPPH自由基能力)分别提高了15.55%(11.85%)、7.61%(3.71%),说明中温能促进酚类物质的释放,提高抗氧化活性。相关性分析显示,荔枝原汁的ΔE与Vc呈负相关,抗氧化活性与总酚、总黄酮呈正相关;聚类热图分析与感官评价表明,联合处理能促进风味物质的释放,且不会造成明显的蒸煮味;联合处理组在4℃贮藏21 d的菌落总数均小于100 CFU/mL。综上,中温联合DMDC处理对荔枝原汁微生物有较好的灭菌效果,且对品质无不良影响,4℃贮藏期可达21 d,该研究为高品质荔枝原汁产业化提供了科学依据。

The effects of dimethyl dicarbonate(DMDC),mild heat and their combination on the microorganisms and physicochemical indices of litchi juice were compared.The results showed that the sterilization effect of DMDC alone or mild heat alone was poor,whilst the number of residual microorganisms in the litchi juice treated by the combination was the lowest,with the total number of colonies and lactic acid bacteria being 0.41 and 0.36 lg CFU/mL,respectively,and no yeast and mold being detected.Compared to fresh litchi juice,DMDC treatment had no effect on the quality of Litchi juice,and the changes in ascorbic acid content and color of the mild heat alone group and the combined treatment group were insignificant,causing the increases in the total phenolics(total flavonoids)by 40.16%(7.16%)and 38.01%(4.35%),respectively,and increases in the ferric ion reducing antioxidant power(DPPH free radical scavenging ability)by 15.55%(11.85%)and 7.61%(3.71%),respectively.These results indicated that mild heat could promote the release of phenolics and improve the antioxidant activity.Correlation analysis showed that theE of litchi juice was negatively correlated with Vc content,and the antioxidant activity was positively correlated with the contents of total phenolics and total flavonoids.Cluster heat map analysis and sensory evaluation revealed that the combined treatment could promote the release of flavor substances without causing a pronounced cooking flavor.The total number of colonies in the combined treatment group stored at 4℃for 21 days was less than 100 CFU/mL.In conclusion,the combination of mild heat and DMDC treatment led to a good sterilization effect on the microorganisms in the litchi juice without causing adverse effects,and the shelf life of the juice was up to 21 d.This study provides a scientific basis for the industrialization of high-quality litchi juice.