Influence of low water activity on the thermal resistance of Salmonella Enteritidis PT30 and Enterococcus faecium as its surrogate in egg powders

Egg powders are increasingly popular ingredients, due to their functionality and compactness, in industrial food production and preparation at homes. However, there is a lack of studies that evaluate the thermal resistance of Salmonella Enteritidis PT30 and its potential surrogate Enterococcus faecium NRRL B-2354 in egg powders. This study examined the log-linear relationship between the thermal resistance of Salmonella Enteritidis (D-value) and the water activity (a w ) of egg powders. The changes of a w in the egg powders with temperature were measured using a Vapor Sorption Analyzer and a high-temperature cell. The D 80 ℃ -value of S. Enteritidis PT30 and E. faecium inoculated in the egg powders preconditioned to three a w levels (0.3, 0.45, and 0.6) at 20 ℃ were determined using aluminum thermal death test cells. The a w values increased (P < 0.05) in all three egg powders when the temperature of the samples was raised from room temperature to 80 ℃. The D 80 ℃ -values ranged from 5.3 ± 0.1 to 25.9 ± 0.2 min for S. Enteritidis while 10.4 ± 0.4 to 43.8 ± 0.4 for E. faecium in samples of the three different a w levels. S. Enteritidis PT30 showed a log-linear relationship between D 80 ℃ -values and a w80 ℃ for the egg powders. This study contributes to our understanding of the impact of a w on the development of thermal treatments for low-moisture foods.