Effects of Freezing and an Alginate Coating on the Shelf Life of Fresh Pistacia Vera

Despite nutritional and economic importance of pistachios, there are still many problems facing their production and marketing. Changes made in the quality of fresh pistachios during storage could reduce their shelf life. Thus, they should be consumed in a short period of time if not stored under proper conditions.

This study was conducted using treatments of freezing (for 0, 1.5, and 3 months at -20 °C) and an alginate-based edible coating (at concentrations of 0, 0.5, and 1%) to increase durability of fresh pistachios in a completely randomized design. The measured parameters included moisture reduction, the peroxide value, and the phenolic content.

Results of the current research showed that freezing temperatures (up to 1.5 months) reduced the peroxide value of fresh pistachios. The use of an alginate-based edible coating (especially at the concentration of 1%) helped maintain some parameters of fresh pistachios, such as the moisture content and peroxide value.

Quality changes in fresh agricultural products during storage are mostly caused by enzyme activities and metabolic alterations. The use of chemical compounds is not welcomed by consumers due to their detrimental effects on the environment and human health. The freezing temperature could extend the shelf life of fresh products by decreasing their respiration rate. The other new technology employs edible coatings, such as alginates, to create a barrier on the surface of fruits to prevent water loss and gas exchange (oxygen and carbon dioxide).