超高压处理对哈密瓜汁中C6、C9 醛、醇形成机理研究

Xinjiang Hami melon is one kind of regional characteristics fruit resources. Currently，melon maturity is relatively concentrated, fresh melon decay rate is much heavier (25%-30%), and the flavor quality deteriorated during processing, which have become the bottleneck of restricting the development of hami melon industry. On the basis of achievement summaries and analysis from preliminary studies, the fresh melon juice was treated by ultra high pressure treatment technology, and the flavor of treated melon juice was analyzed by GC-MS and GC-O. The flavor fingerprint was validated by using the chemometrics method (PCA and PLS-DA) to determine the accuracy and effectiveness on the quality control of hami melon juice.the content change of C6, C9analysis of aldehydes, alcohols was determined by Using KI and internal standard method. After treatment, the effects on the substrate and product of LOX metabolic pathway in the hami melon juice were studied. The changes of enzyme activity and structure of each sample were determined by using PAGE, CD and fluorescence spectrophotometric analysis. The correlation analysis of C6, C9, alcohol, aldehyde aroma, related enzyme activity, metabolic substrate and product , then using random verification methods to verify the correlation. Through the above analysis, it can be determined which effector substrate and enzyme contribute greatly to each of the C6, C9 characteristic flavor compounds, further revealing the mechanism of Xinjiang hami melon characteristic flavor. As a scientific basis, the mechanism of C6, C9 aldehyde, alcohol metabolic regulation in hami melon juice by ultra high pressure treatment was revealed gradually. The anticipated results of this research serve as a theoretical basis for melon juice non-thermal processing, the improvements of controlled flavor technologies and the upgrading of product quality. The results related with this project and other continuity exploration will play an important role in promoting the development of Xinjiang hami melon industry.

新疆哈密瓜为区域特色瓜果资源，目前由于其成熟期较集中，鲜瓜腐烂率高（25%-30%），及热加工过程中香气劣变现象已成为限制哈密瓜产业发展的瓶颈。本项目在前期对哈密瓜汁香气及品质研究成果总结分析基础上，采用GC-MS-O联用技术分析超高压处理哈密瓜汁香气组分，以系统聚类和相似度法构建哈密瓜汁特征香气指纹图谱，并采用KI和内标法分析确定C6、C9 醛、醇化合物含量变化；同时研究超高压处理对哈密瓜汁LOX 代谢途径的底物和产物影响；采用PAGE、园二色谱和荧光光度计法分析每个样本关键酶活性与结构的变化；结合PCA 技术分析C6、C9 醛、醇香气、相关的酶活性、底物与产物相关性分析，并采用随机验证等方法对其相关性进行验证，挖掘并验证与C6、C9醛、醇香气相关底物与酶，深入解析超高压处理对哈密瓜汁中C6、C9 醛、醇形成机理研究。预期为哈密瓜汁加工、呈香调控等技术改进及产品品质升级提供坚实理论基础。

新疆哈密瓜为区域特色瓜果资源，目前由于其成熟期较集中，鲜瓜腐烂率高（25%-30%），及热加工过程中香气劣变现象已成为限制哈密瓜产业发展的瓶颈。本项目在前期对哈密瓜汁香气及品质研究成果总结分析基础上，采用GC-MS-O联用技术分析不同超高压处理、高温瞬时及微波处理的哈密瓜汁香气组分，采用LEfSe分析了热处理和非热处理中引起风味变化的关键物质；同时研究不同处理对哈密瓜汁脂肪酸和氨基酸代谢途径中底物和产物影响；采用PAGE、园二色谱和荧光光度计法分析每个样本关键酶活性与结构的变化；结合R语言和Cytoscape可视化分析C6、C9 醛、醇香气、相关的酶活性、底物与产物之间的关系。结果表明高温瞬时加热样品中风味变化主要体现在乙酸酯类，C6、C9醇醛类和胺类物质的变化；在微波处理中，主要是醇醛类的变化；在不同超高压条件下使哈密瓜汁风味产生的变化的关键物质主要是乙酸酯类和C6、C9的醇醛类。热处理组中与香气相关主要是PLA2、异亮氨酸、α-亚麻酸、LOX、AAT、花生四烯酸，且在热处理组中，氨基酸代谢占主导地位。在高压处理组中，与香气物质相关的有PLA2、赖氨酸、棕榈酸、苯丙氨酸等，根据Vegan分析高压处理组中脂肪酸与香气物质的相关性大于氨基酸与香气物质的相关性。通过对数据的充分挖掘深入解析不同处理对哈密瓜汁中C6、C9 醛、醇形成机理研究，预期为哈密瓜汁加工、呈香调控等技术改进及产品品质升级提供坚实理论基础。