ass日本风韵熟妇pics男人扒开女人屁屁桶到爽|扒开胸露出奶头亲吻视频|邻居少妇的诱惑|人人妻在线播放|日日摸夜夜摸狠狠摸婷婷|制服 丝袜 人妻|激情熟妇中文字幕|看黄色欧美特一级|日本av人妻系列|高潮对白av,丰满岳妇乱熟妇之荡,日本丰满熟妇乱又伦,日韩欧美一区二区三区在线

The low-alcohol Zaosu pear wine was prepared and stored at 4℃ and 25℃ for 60 days respectively to investigate the changes in browning factors and volatile aroma compounds. The activity of polyphenol oxidase, peroxidase and phenylalanine ammonia lyase, and the content of total amino acids, reducing sugar, total phenols, 5-hydroxymethylfurfural as well as the browning degree were measured every seven days during the storage of wine samples. The volatile aroma compounds in pear wine were detected at the end of storage by using SPME-GC/MS. Results showed that the POD activity of Zaosu pear wine was rapidly decreased and the content of total amino acids and polyphenols was reduced by 62%~70% and 23%~31%, respectively. Meanwhile, 5-hydroxymethylfurfural content and browning degree were constantly increased during the storage of pear wine. The evolutions of total amino acids, polyphenol, 5-hydroxymethylfurfural and browning degree were perfectly fitted to the zero order kinetic equation. Correlation analysis showed that total amino acids, polyphenols and 5-hydroxymethylfurfural had a significant impact on the browning of pear wine. The content of terpenes, esters and carbonyl compounds was increased, while the level of higher alcohol and volatile fatty acids was significantly decreased in wine samples after 60 days of storage. The correlation coefficients between 15 key aroma compounds (OAV>0.1) and the main browning factors were greater than 0.8. The research results had potential application value for controlling the browning of Zaosu pear wine.