Combined treatment of β-resorcylic acid and capric acid enhances mild heat pasteurization for inactivating Salmonella Typhimurium in orange juice

This study aimed to develop a pasteurization method against Salmonella enterica serovar Typhimurium in orange juice using low concentrations of naturally derived antimicrobials, β-resorcylic acid and capric acid, under mild temperature conditions based on their synergistic bactericidal interactions. Response surface methodology was used to construct a model based on four variables, namely β-resorcylic acid (1, 3, 5, 7, and 9 mM), capric acid (0.05, 0.10, 0.15, 0.20, and 0.25 mM), treatment temperature (35, 40, 45, 50, and 55 °C), and time (1, 2, 3, 4, and 5 min), and the resulting model was used to predict the reduction in the content of fastidious bacteria (S. Typhimurium) in orange juice and to identify the optimal treatment combination for juice pasteurization. A second-order quadratic model for Salmonella reduction showed a high regression coefficient (R² = 0.9503), and the accuracy of the predictive model was also verified (R² = 0.9317). The optimal conditions determined by ridge analysis were 8.43 mM β-resorcylic acid combined with 0.10 mM capric acid at 43.46 °C for 3.03 min, and these yielded an estimated 7.41-log reduction. Treatment times <30 s under the optimal conditions also resulted in a >5.7-log reduction. The combined treatment did not affect either the pH or sugar concentration in brix, and average pH and sugar concentration values of 3.86 and 11.05% were observed, respectively. The distinct advantage of the developed method is its ability to effectively reduce the content of S. Typhimurium over a short time under low temperature conditions through the addition of consumer-preferred naturally derived antimicrobials. The predictive model could be used to determine the most cost-efficient amounts of antimicrobial agents and conditions (treatment temperature and time) for sterilizing orange juice.