Control of Salmonella Typhimurium DT 104 and Salmonella Enteritidis PT 30 on almonds by vacuum-packaged hot water immersion and dry-heat roasting treatments.

BACKGROUND: This study investigated the efficacy of vacuum-packaged hot water (VPHW) immersion as an alternative to conventional dry-heat roasting for almond pasteurization, focusing on Salmonella inactivation and selected physicochemical quality attributes. Almonds inoculated with Salmonella Typhimurium DT 104 and Salmonella Enteritidis PT 30 were treated by VPHW immersion (70-90 °C) and roasting (120-140 °C). RESULTS: Vacuum-packaged hot water achieved greater microbial inactivation at lower temperatures than roasting. Treatment with VPHW at 90 °C for 10 min resulted in population reductions of 4.64 and >4.99 log CFU g-1 for S. Typhimurium DT 104 and S. Enteritidis PT 30, respectively, whereas roasting at 140 °C for 20 min was required to achieve comparable inactivation. A reversal in resistance was observed: S. Typhimurium DT 104 exhibited greater resistance to VPHW, whereas S. Enteritidis PT 30 showed higher tolerance to roasting. Physicochemical analyses further highlighted the advantages of VPHW. Roasting caused significant browning (decreased L*, a*, and b* values) and accelerated lipid oxidation at 140 °C, whereas VPHW-treated almonds maintained color and lipid integrity comparable with those of raw controls. Vacuum-packaged hot water also maintained antioxidant capacity comparable with untreated almonds, whereas high-temperature roasting led to oxidative degradation. CONCLUSION: These findings suggest that VPHW, by maintaining a relatively high-moisture processing environment and reducing oxidative stress through vacuum-packaged conditions, is an effective technology for ensuring microbiological safety while minimizing degradation of the visual and chemical quality of almonds. © 2026 Society of Chemical Industry.