THERMOSONICATION VS. THERMAL PROCESSING: INACTIVATION KINETICS OF LACTICASEIBACILLUS CASEI IN ORANGE NECTAR FOR POSTBIOTIC BEVERAGE PRODUCTION

Postbiotics, derived from inanimate microorganisms and their components, offer health benefits like improved gut health. This study aimed to compare the inactivation kinetics of Lacticaseibacillus casei in fermented orange nectar using thermosonication (TS) and thermal processing (TH) to produce a postbiotic beverage. TS (10.6 W/mL) and TH were applied at 50 ± 2, 55 ± 2, and 60 ± 2 °C. The impact of pulsed operation and different ultrasound power densities were also investigated. TH followed the linear Bigelow model, with D-values decreasing from 11.12 min at 50 °C to 1.44 min at 60 °C (Z-value = 11.28 °C). In contrast, TS followed a non-linear Weibull model, with the inactivation rate (b) increasing from 1.77 at 52 °C to 4.56 at 60 °C. TS achieved a significantly faster inactivation than TH at the same temperatures. Higher acoustic power density (10.6 W/mL) resulted in 1.86-fold greater inactivation compared to 2.8 W/mL. Importantly, pulsed thermosonication (3 s ON – 1 s OFF) demonstrated similar inactivation efficiency to continuous operation, with a 25% reduction in energy consumption. Thermosonication offers a more efficient method than conventional thermal processing for inactivating L. casei, providing a promising approach for optimizing postbiotic beverage production.