Postharvest reduction of Salmonella on Hass avocado epicarp by hot water immersion and evaluation of fruit quality

Abstract

Salmonella contamination of fresh produce, including avocados, poses a significant public health concern. Effective postharvest interventions are needed to reduce pathogen loads without compromising fruit quality. This study evaluated the efficacy of hot water (HW) immersion (70 or 80 °C for 1, 2, and 4 min) in reducing loosely (LA) and strongly attached (SA) Salmonella cells on Hass avocado epicarp, and its effect on background microbiota and fruit quality. Whole avocados, inoculated or uninoculated, were stored at 25 °C for 72 h before being washed and treated by HW immersion. The LA and SA cells of Salmonella, aerobic plate count (APC), and yeasts and molds (YM) were enumerated on avocado epicarp. Hot water immersion was equally effective (P > 0.05) in removing LA and SA cells of Salmonella and background microbiota. Temperature and immersion time significantly influenced Salmonella reductions (P < 0.05), with 80 °C for 4 min being the most effective, achieving 5.1 and 4.8 log CFU/avocado reductions for LA and SA. Immersion time did not significantly affect (P > 0.05) the reductions in background microbiota. Treatments at 80 °C yielded the greatest APC and YM reductions (P < 0.05), with maximum reductions of 3.5 and 4.3 for LA, and 3.7 and 4.2 for SA. No significant differences (P > 0.05) were observed in pulp color, firmness, total fat content, or flavor between HW-treated and untreated samples. These results support the use of HW immersion as a postharvest decontamination strategy that enhances microbial safety while maintaining avocado pulp quality.