Pasteurization of bael fruit (Aegle marmelos) juice using high-intensity pulsed light treatment

The ability of high-intensity pulsed light (PL) treatment (0-4.5 min) to pasteurize bael juice (beverage) was investigated. Hydrolyzing enzymes like polygalacturonase (PG) used for bael juice extraction were usually thermally inactivated. Therefore, inactivation of non-pathogenic surrogates (Escherichia coli (EC), Salmonella Typhimurium (ST), Listeria monocytogenes (LM)), spoilage yeast (Saccharomyces cerevisiae (SC)), a cocktail of all microorganisms, native microbial groups (aerobic mesophile (AM) and yeast-mold (YM)), PG enzyme, and native spoilage enzymes (polyphenol-oxidase (PPO), peroxidase (POD)) were analyzed. EC, LM, SC, and AM were the most resistant pathogen in juice, pathogen in buffer, spoilage microorganism, and native microflora, respec-tively. They required 0.21, 0.20, 0.53, and 0.64 kJ cm-2 available fluence (Fa), respectively, for achieving a 5-log reduction in bael juice. No significant sub-lethal injury in all four microorganisms in the juice was observed. The order of resistance for enzymes was PG < POD < PPO. In juice, a maximum of 73.5% inactivation of PPO activity was achievable at the most severe treatment of 1.64 kJ cm-2 Fa with 55 degrees C initial sample temperature. Compared to thermal control (95 degrees C, 5 min), 73.5-90% inactivation of resistant enzymes with PL irradiation was achieved along with enhanced nutritional qualities, mild colour change, and lower browning in the bael juice.