Effect of Freezing and Vacuum Packaging on Quality Properties of Pistachio Powder During Storage

Pistachio powder is a product used today in confectionery, ice cream, pistachio paste and other foods. Considering the higher rate of spoilage and oxidation in pistachio powder, developing methods to increase the shelf-life of this product is therefore important. In this study the effect of  freezing and vacuum packaging on the quality characteristics of pistachio powder during storage was investigated. The effect of packaging conditions (vacuum or air packaging), storage temperature (25°C, -18°C) and storage time (0, 1, 2, 3 and 4 months) on chemical (free fatty acids, acid value, peroxide value), physical (moisture content and color indexes of L*, a* and b*), and sensory (odor, taste, color, texture and overall acceptance) characteristics were studied. The results revealed that the peroxide value, acid value and free fatty acids in frozen and vacuum containers were lower than those packed without vacuum at room temperature. The results of sensory evaluation indicated a significant difference (p< 0.05) in samples.The best quality characteristics in terms of odor, taste, and overall acceptance belonged to the pistachio powder packed in vacuum and frozen conditions; however, in terms of texture , the containers packed and stored in ambient conditions showed better results. In all cases, the quality of pistachio powder decreased during the storage period. There was no significant difference between samples in moisture content, color indices of L*, a*, b* and sensory evaluation of color. It was generally found that packaging under vacuum and freezing could increase the shelf life of pistachio powder.