Surface Disinfection and Food Safety Enhancement in Pistachios Through Ultraviolet Light Application

Abstract

Pistachios are prone to contamination by soilborne and foodborne microorganisms after harvest, affecting their safety and quality. Due to unfavorable alterations in the product's physical and sensory qualities, several processing methods to lessen the microbial load on pistachios have not been reported as successful or practicable. This study evaluates the impact of ultraviolet-C (UV-C) light treatment on pistachios' physical, chemical, microbiological, and sensory properties. UV-C treatments were applied at 900, 1,800, and 2,700 seconds, with a light intensity of 0.044 W/cm², corresponding to doses of 39.6, 79.2, and 118.8 J/cm², respectively. Results showed that increasing UV-C dose led to a significant increase in total fat content and peroxide value, total antioxidant activity, L* and b* total phenolic substance content, a significant decrease in total chlorophyll content, a* with no significant change in titratable acidity (P ≤ 0.05). The decrease in total mesophilic aerobic bacteria, total mold and yeast, total Salmonellae and total coliform counts were 3.10, 3.38, 3.2 and 2.97 log cfu/g, respectively (P ≤ 0.05). Sensory evaluations indicated that UV-C-treated samples, particularly those at 79.2 and 118.8 J/cm², received higher scores than control samples (P ≤ 0.05). The concentrations of the major fatty acids, oleic, butyric, linolenic, and palmitic acids, showed fluctuations with the applied energy. These findings demonstrate that UV-C light treatment effectively inactivates microorganisms while enhancing bioactive compounds and maintaining product quality.