Evaluation of Anti-Fungal Activity of Chitosan and Its Effect on the Moisture Absorption and Organoleptic Characteristics of Pistachio Nuts

Abstract

Pistachio is one of the main export products of Iran and Iran is one of the largest producer and exporter of pistachio in the world. Unfavourable environmental conditions during storage, causes a sharp drop in quality of product through musty and toxin production, especially aflatoxin by Aspergillus flavus and Aspergillus parasiticus, Absorption of foreign odors and moisture, Tissue destruction of undesirable flavour. The aim of this study was to study the anti-fungal activity of chitosan and its effect on the organoleptic characteristics of pistachio nuts. Therefore, using acetic acid 1% V / V, chitosan concentrations of 0.5%, 1% and 1.5 % V/W was prepared and pistachios were coated by these solutions. Also acetic acid at concentration 1% without chitosan was used as a treatment for coating to determine the antimicrobial effect of acetic acid. The results showed that chitosan significantly (p <0.05) inhibited the growth of the Aspergillus and its effect was increased with increased concentration. Chitosan also prevented moisture absorption and weight change in pistachio nuts, while chitosan concentration showed no significant effect on moisture absorption and weight change of pistachio nuts. Chitosan 1.5% had a significant effect (p <0.05) on the flavour of pistachio, but other concentrations had no effect. However, chitosan in general had no significant effect (p <0.05) on color, texture and acceptability of pistachio nuts.