A novel approach to suppress enzymatic browning of packed fresh pistachio (Pistacia vera L.) through enhanced calcium absorption by lecithin

Abstract

Various calcium nitrate solutions, including control (distilled water), calcium nitrate 0.4%, and calcium nitrate enriched with lecithin 0.2%, were used to improve the postharvest quality of two cultivars: ‘Akbari’ and ‘Kaleh- Ghoochi’ pistachio fruit two weeks after full bloom. After pistachio harvest, it was packed and transferred to cold storage at 4 ± 1°C with 85 ± 2% relative humidity for 45 days. Our findings indicated that the calcium nitrate treatment enhanced antioxidant activity and overall pistachio characteristics during storage compared to the control group. While the Kaleh-Ghoochi cultivar showed a decline in hull appearance quality when treated with calcium nitrate enriched with lecithin, the pistachio remained desirable. Notably, this treatment exhibited greater effectiveness in certain characteristics. For instance, the Akbari cultivar treated with calcium nitrate enriched with lecithin showed improved hull appearance (3%), greater firmness (25%), and lower water activity (1%). Conversely, the Kaleh-Ghoochi cultivar exhibits deteriorated hull appearance (12%), reduced firmness (32%), lower water activity (2%), and elevated superoxide dismutase (SOD) enzyme activity (57%). Additionally, antioxidant activity was higher (7%), while phenolics content was lower (2%). The combination of calcium nitrate and lecithin-surfactant provides an innovative approach to mitigate hull browning and preserve the quality of pistachio fruit during storage period.