The effect of high‐pressure processing or thermosonication in combination with nisin on microbial inactivation and quality of green juice

Abstract

The impact of high-pressure processing (HPP) or thermosonication (TS) in combination with nisin on the microbial inactivation of green juice (celery stalk, apple, cucumber, parsley) and changes in its quality was investigated. Microbial inactivation with HPP at 600 MPa resulted ≥7 log reduction of Escherichia coli, whereas 5 and 7 log reduction of Listeria innocua were attained after combining with 100 and 200 mg/L of nisin, respectively. With TS at 60°C, 7.42 log reduction of E. coli was achieved after 6 min; meanwhile, combining with 100 mg/L of nisin, 7 log reduction of L. innocua was detected after 3 min. Neither HPP nor TS did not alter pH and total soluble solids; however, significant changes were observed in color. Green juice predominantly followed Newtonian flow behavior and the viscosity did not change significantly after using both technologies. Results indicated that HPP or TS in combination with nisin is a viable option for green juice pasteurization. Practical applications Green juice is a heat-sensitive food product with numerous health benefits. Selected nonthermal food processing technologies using HPP or TS in combination with nisin revealed promising results for the inactivation of both gram-negative and gram-positive bacteria in green juice without adverse effect on quality including pH, total soluble solids, color, and viscosity. With nisin combination, either HPP or TS could be used as an effective nonthermal pasteurization process for high-quality green juice production.