Effect of different time of precooling on bioactive compound and fruit quality of fresh Pistachio during storage in low temperatures

In recent decades, demand for fresh produce has increased due to changes in consumer attitude. Fresh pistachio fruits have bioactive compounds and antioxidant properties that play important role in health food diet. Also, maintenance of quality and appearance of fresh pistachio plays an important role in increasing the economic value of this produce. To evaluate qualitative properties of fresh pistachio cv. Ahmadaghaei, different time of precooling 4, 16, 28, 40 hr. were considered and fruits were stored at 3±1oC and 85±5 % R.H. as first factor and storage time (35 and 55 day) as second factor. Different parameters include hull and fruit water content, hull, shell and kernel color indices, anthocyanin content, hull and kernel phenolic compounds, antioxidant activity and PPO activity were measured. The results indicate that delayed cooling time had significant effects on hull and fruit water content, hull, shell and kernel color indices, anthocyanin content, hull and kernel phenolic compounds, antioxidant activity. The fruits that were cooled down in 16 hr. had better quality than others. The results also showed that the highest PPO activity was recorded for those fruits which cooled after 16 hr. Therefore, according to the results of this study, 16 hr. delay in cooling of fresh pistachio fruit is recommended to improve the quality of fruit during storage.