The Study On Browning Phenomenon And Influencing Factors Of Browning During Storage Of Grapes

It is easy to occur browning in grape tissues during low temperature storage, the browning symptoms can happen at edible parts such as grape peel and flesh or inedible spike-stalk, study on browning rarely involve in peel, flesh, seed and spike-stalk for simultaneous analysis, analysis of the relationship between them or effect on browning is less. Manai grape of Hebei Province and Rosario Bianco grape of Tianjin were selected as test materials, through two years of investigation, studied change rule of browning of different tissues during storage. Different tissues on microbiological analysis were studied after 90 d storage, distinguished fungal species and difference in 7 parts. In addition, studied browning, related enzymes activity, chlorophyll a and carotenoid content in 2014 and 2015; studied browning difference between Manai and Rosario Bianco. Besides, in order to analyse effect of storage time on browning, physiological quality of Rosario Bianco grape was determined; the correlation analysis of different parts of browning related enzymes and total phenol content was carried out. At last, after 85 d cold storage, Rosario Bianco grape was used to storage at room temperature, found out the change rule for different browning level during shelf time, studied relationship between surface of browning and inner quality. The main research results are as follow:Grape peel change was bright green, reddish, brown; grape pulp white green gradually disappeared, and part transformed to shallow black, red brown; spike-stalk change was bright green, yellow green, brown, it also showed sub section features. The activity of browning related enzymes were higher in spike-stalk and grape peel. All of seven parts have aspergillus niger, there was no difference in fungal species between green and brown. Although microorganism could not directly cause browning, it could indirectly destroy tissue integrity, cause decline of antioxidant capacity, and easily lead to browning.By analyzing the influencing factors of browning, the results were: PPO activity presented upward trend after first fall for grape peel in two years, there had little difference in different years; and brown spike-stalk activity increased gradually with storage time, effect of years was significantly different(P<0.05); resulted showed that PPO and POD activity in Manai grape peel and spike-stalk were higher than rosario bianco at the end of storage time, higher enzyme activity was one reason of Manai was more easily to browning.Compared with CK treatment, CT2 treatment could significantly reduce rotting rate, delay the process of grape peel color change, and inhibitory effect on breathing intensity reflected after the second survey period. CT2 group could reduce descent speed of TA content, delay time for VC content to begin to fall, preservative treatment could maintain fruit quality for longer storage time.The shelf storage test indicated that 1 grade and 2 grade browning fruit had more obvious browning change on surface than 3 grade, between physiological quality and a was quadratic relationship, if running room temperature shelf storage after a period of low temperature storage, the fruit quality would change quickly.