Combined application of polyamines and chitosan on bioactive compound and browning of fresh pistachio

In order to maintain the quality of pistachio fruit and evaluation of fruits color changes and browning an experiment was conducted as block completely randomizes design as factorial with three factors: perharvest polyamines forms applications: putrescine, spermidine, and spermine at 1 mM; chitosan (0 and 1%) and storage periods (0, 20 and 40 days of storage) with three replications on ‘Akbari’ cultivar. In this study fruits and hull water, hull and shell indices, pigments, hull and kernel phenolic compounds, polyphenol oxidase and antioxidant activity were measured. The results showed that hull and kernel phenolic compounds, polyphenol oxidase, antioxidant activity, anthocyanin, hull water, hull color indices were decreased during storage period and perharvested application of polyamines maintained these traits during storage. Among polyamines, putrescine had the highest influence on these traits compared to spermidine and spermine. The results also showed that chitosan application also maintains hull and kernel phenolic compounds, polyphenol oxidase, antioxidant activity, anthocyanin, hull water, hull color indices in pistachio treated-fruits and untreated-fruits with polyamines during storage. The results also indicated that combined application of putrescine and chitosan had the greatest effect on maintaining pistachio characteristics and reducing the percentage of fruits browning during storage. Therefore, according to the results of this study, the use of putrescine with a concentration of 1 mM before harvest following chitosan coating can plays an important role in maintaining the quality of fresh pistachio fruit during storage.