تاثیر پوشش خوراکی کیتوزان با وزن های مولکولی و غلظت های مختلف بر واکنش های اکسایشی مغز پسته

Abstract‎iran is one of the largest pistachio producer and exporter‏ ‏in the world. under unfavorable conditions during ‎storage, pistachio quality will be reduced due to undesirable reactions. this study was conducted to evaluate ‎the influence of chitosan coating with different molecular weights and concentrations on oxidation activity in ‎the akbary variety of pistachio nuts. therefore, using acetic acid as 1% (v/v), chitosan with low molecular ‎weight (lmc) and medium molecular weights (mmc) at concentrations of 0.5%, 1% and 1.5% v/w were ‎prepared and pistachios were coated by them. in order to prepare control group, coating was performed ‎with water and acetic acid as 1% v/v. coated pistachios were packed in polyethylene bags and kept at room ‎temperature and relative humidity (25-27 °c and 35-45%) for six months. samples were ‎examined every two weeks for peroxide and thiobarbituric acid value during storage ‏.‏‎‎ the results showed that‎ during ‎storage, chitosan coating reduced the rate of oxidation significantly (p < 0.05). the lmc exhibited higher anti-‎oxidant activity than mmc and increased concentration correlated with higher antioxidant activity. the ‎thiobarbituric acid value of pistachios was always zero due to non-formation of secondary compounds of ‎oxidation reactions. in this research, lmc was found ‎appropriate edible coating material for pistachio nuts. key words: antioxidant activity, chitosan coating, concentration, molecular weight, pistachio nuts