超高压和热处理对荔枝汁品质的影响研究

Effect of Thermal and Ultra High Pressure Treatments on Quality Characteristics of Litchi Juice

[目的]系统分析比较新鲜荔枝汁经热处理和超高压处理后主要理化性质及品质的变化情况。[方法]对比分析了荔枝汁经超高压与热处理后,在达到商业无菌的基础上,对其感官品质、理化性质和营养成分的影响。[结果]试验表明,超高压处理对荔枝汁色泽无显著影响,但热处理后色泽明显加深。PPO经热处理和超高压处理后均未检测到活性,热处理和超高压处理对可溶性固形物、pH、总酸度和电导率影响不明显。还原糖在3个组之间没有显著差异;总多酚、维生素C和氨基酸组成含量经热处理后明显降低,但超高压处理对其没有影响。超高压处理可以很好地保留荔枝的香气物质,热处理对荔枝的香气物质损失较严重。因此,超高压处理对于荔枝果汁有很好的杀菌效果,能一定程度地钝化酶的活性,同时能较好地保持荔枝果汁中的天然营养成分。[结论]超高压处理是一种很有前景的荔枝非热加工技术,该研究可为超高压技术在荔枝汁加工中的应用提供参考。

[ Objective ] To analyze the variation of main physicochemical properties and quality of fresh litchi juice after thermal and ultra high pressure treatments. [ Method] This research assessed the effects of different thermal and ultra high pressure treatments on the sensory quality, physicochemical properties and nutrients of litchi juice. [ Result] The results showed that ultra high pressure treatment had no significant effect on the color of litchi juice, but thermal treatment has a significant effect. After thermal and ultra high pressure treatments, the contents of solu- ble solid, pH value, total acidity and electrical conductivity did not change, PPO activity was not detected. There were not changed signifi- cantly in Lychee juice of reducing sugar by thermal and ultra high pressure treatments, and there were reduced significantly on the total poly- phenols, vitamin C and amino acids content by thermal treatments. Total polyphenols, vitamin C and amino acid content did not change after the ultra high pressure treatment. Ultra high pressure treatments is a good way to keep the aroma of litchi juice more than thermal treatment. These results indicate that ultra high pressure treatment on litchi juice has a good bactericidal effect, certain passivation effect on food quality enzyme and a good retention of nutritional ingredients, so ultra high pressure is a potential non-thermal sterilization technique for litchi processing. [ Conclusion] This research provides technical basis for applying ultra high pressure sterilization of litchi juice.