Effect of Harvesting Time and Delay in the Hulling Process on the Aflatoxin Content of Pistachio Nuts

Harvesting time is one of the important factors that affect the quantitative and qualitative characteristics of pistachio nuts. Delaying in harvest time decreased intact nut percentage and increased cracked nut percentage. Furthermore, harvest time had significant effects on overmaturity, and the highest and lowest values were observed at the last time (Oct. 22) and at the first harvest time (Sep. 6). Results of harvesting time on aflatoxin contamination (without delay in processing) showed that the highest aflatoxin content was 0.33 ppb on October 22 and the lowest was 0.1 ppb on Sep. 6. Effects of processing delays on aflatoxin content showed that 0 and two-delay hours had no significant effects, but 12, 24, and 48-hour delays caused a significant increase in aflatoxin content. Delaying the harvest time increased the splitting percentage. Delay in processing time, increased nut staining, and aflatoxin content. The effects of harvest time and delays in processing showed that the highest stained nuts (11.3%) were found at the last harvest time and after a 48-hour delay in processing time. The lowest measured aflatoxin content at harvest was 0.1 ppb and the highest was 66.10 ppb on Sep. 6 (without delay in processing) and Oct. 22 (with 48 hours’ delay in processing), respectively. The hulling process of the harvested pistachio nuts must be carried out immediately after harvest. Processing delays must not be more than 24 hours after harvest. Considering the lowest early splitting, hull cracking, over maturity, shell staining, and aflatoxin content, September 6 is recommended as the best time to harvest pistachio nuts.