Influence of Thermal and Intensive Pulsed Light Treatments on Polyphenoloxidase Structure, Saccharomyces cerevisiae Morphology, and Phenolic Profile of Bael (Aegle marmelos) Beverage.

The influence of pulsed light (PL) treatment at optimum condition (1.64 kJ/cm available fluence) was observed on structural changes in polyphenoloxidase (PPO), morphological changes in the cells of Saccharomyces cerevisiae, bioactive profile of bael (Aegle marmelos) beverage, and its sensory quality. Sensory data were processed with fuzzy logic. Thermal-processed (95°C, 5 min) beverage was considered a treatment reference for the entire study. In addition to protein unfolding and aggregation, the maximum reduction of β-sheet by PL and the maximum increase of α-helix by thermal were responsible for PPO inactivation. The chosen pulsed irradiation and thermal processing conditions were capable of obtaining 56.4% and 90% inactivation of PPO (the most resistant entity in the bael beverage), respectively. PL-treated cells of Saccharomyces cerevisiae showed a wrinkled surface, flattened appearance, and cell lysis. Thermal and PL resulted in a 78.4% and 75.2% reduction in average cell diameter, respectively. About 49 phenolic compounds were detected in the untreated beverage. After thermal and PL treatment, a respective loss of 15 and 13 bioactive compounds indicates better bioactive retention by PL processing. For example, compounds like umbelliferone, marmin, marmesinin, rutin, and 1-O-E-cinnamoyl-(6-arabinosylglucose) were lost due to thermal processing, whereas 8-methyldihydrochelerythrine, 6-feruloylglucose 2,3,4-trihydroxy-3-methylbutylglycoside, and hexyl heptanoate were lost due to PL processing. Apart from this, only a few bioactive compounds were discovered after treatment. Taste was perceived as the most essential sensory parameter. The sensory quality of PL irradiated was slightly better than that of thermally treated beverage, with crisp-sample-score of 3.25 and 3.19, respectively. PRACTICAL APPLICATION: The present work focuses on investigating the influence of high-intensity pulsed light (PL) on the inactivation mechanism of polyphenoloxidase enzyme (through circular dichroism), the inactivation mechanism of Saccharomyces cerevisiae (through scanning electron microscopy), the phenolic profile of bael beverage (through liquid chromatography-mass spectroscopy), and sensory evaluation augmented with fuzzy logic. A detailed comparison of the inactivation mechanism of PL with thermal pasteurization conditions will improve our understanding. Impact on the phenolic profile of bael beverage due to PL and thermal treatment presents crucial information for understanding the processing consequences of nutrients. Furthermore, data from the sensory analysis through an intelligent technique, like fuzzy logic, gave more accurate and reliable results.