Feedback control of apple juice quality during storage via multiple, mild in-situ processing treatments

Abstract

Current food preservation practice involves a single intensive kill-step followed by isolation of the product within a package: an open-loop control strategy. Alternatively, a closed-loop control strategy, wherein the food is minimally processed as an initial stabilization (first kill-step) but the option for processing later as-needed is available, can improve food safety and quality levels. For this purpose, unpasteurized apple juice (330 mL), packed in sterilized electrode-embedded laminate pouches, was stored at 4 °C for 45 days after processed by pasteurization (water-bath; at 71.1 °C for 3 s) and moderate processing (ohmic heating; 25 V/cm; 65 °C for 30 s) once or with periodic reprocessing, by ohmic heating. Reprocessing was conducted three times (after Day 10, 24, and 42) based on microbial counts, and resulted in microbial counts maintained lower than 2.1 log CFU/mL over about 5 weeks. Results of sensory analysis showed that apple juice could be maintained at an acceptable quality in the selected sensory attributes over 6 weeks of storage by using multiple mild electrothermal processes, instead of one terminal kill-step. This approach enables proactive response to microbial growth during storage and promotes reduction of waste.