Thermal resistance of Salmonella in low-moisture high-sugar products

Abstract

Recent foodborne outbreaks in low-moisture foods were caused mostly by Salmonella. The main common carbohydrates in low-moisture high-sugar products are D-glucose and D-fructose. There is a lack of information on the thermal resistance of Salmonella in pure sugar and high-sugar products with low water activity (aw) levels. The objective of this study was to study the thermal resistance of Salmonella Enteritidis PT30 in sugar products. Two pure sugars (glucose and fructose) and honey powder were selected for this research. The initial aw and moisture content for glucose, fructose, and honey powder are 0.30, 0.30, 0.40 and 0.02, 0.15, and 0.50% db., respectively. The D-values of Salmonella in different sugar products are determined at low aw levels (0.18, 0.30, 0.40, and 0.50 measured at 80 °C). The results showed that the D80 °C-values of S. Enteritidis PT30 decreased with increasing aw of all samples. At aw80 °C 0.18, S. Enteritidis PT30 in glucose powder has higher D-value than those in fructose and honey powder whereas, at aw80 °C 0.30, 0.40, and 0.50, S. Enteritidis PT30 in fructose powder has higher D-values than glucose and honey powder at 80 °C. Zaw values of S. Enteritidis PT30 in fructose and honey powder are comparable but was lower in glucose because of the phase change. The results of this study provide insights on understanding the thermal resistance of Salmonella in sugars and guidance on thermal process design to improve the safety of low-moisture high-sugar products.