Effect of microfluidization on quality characteristics of sapodilla (Manilkara achras L.) juice

Effects of Thermosonication on the Antioxidant Capacity and Physicochemical, Bioactive, Microbiological, and Sensory Qualities of Blackcurrant Juice

This study investigated the effects of thermosonication (TS) on the quality of blackcurrant juice, along with its physicochemical properties, bioactive compounds, antioxidant capacity, and microbiological and sensory qualities. The treatments included raw juice (RJ), pasteurized juice (90 °C, 1 min, PJ), and thermosonicated juice (480 W, 40 kHz at 40, 50, or 60 °C, for 10, 20, 30, or 40 min, TJ). The results indicated that the effects of pasteurization and thermosonication on the pH, total soluble solids, and titratable acidity of the juice were not significant (p > 0.05). However, the cloudiness, browning index, and viscosity were significantly increased (p < 0.05), and the color properties of the blackcurrant juice were improved. The total phenolic, flavonoid, and anthocyanin contents of TJ (treated at 50 °C for 30 min) were increased by 12.6%, 20.9%, and 40.4%, respectively, and there was a notable decline in ascorbic acid content after the pasteurization treatment, while the loss was minor in all TJ samples compared with RJ. The scavenging ability of 1,1-diphenyl-2-pyridyl and hydroxyl radicals increased to 52.77% and 50.52%, respectively, which were significantly (p < 0.05) higher than those in the RJ and PJ samples. In addition, both pasteurization and thermosonication resulted in a significant (p < 0.05) reduction in microbial counts, while there were no significant (p > 0.05) differences in the sensory parameters compared with the RJ samples. In conclusion, this study suggests that TS is an effective method that can be used as an alternative to pasteurization to improve the quality of blackcurrant juice.

Effect of High-Pressure Micro-Fluidization on the Inactivation of Staphylococcus aureus in Liquid Food

High-pressure homogenization has been extensively studied for its excellent homogenization effect and the prospect of continuous liquid food production, but its sterilization ability still needs to be improved. In this study, we replaced the homogenization valve with two opposing diamond nozzles (0.05 mm inner diameter) so that the fluid collided at high velocity, corresponding to high-pressure micro-fluidization (HPM). Moreover, HPM treatment significantly inactivated Staphylococcus aureus ~7 log in the liquid with no detectable sub-lethal state at a pressure of 400 MPa and a discharge temperature of 50 °C. The sterilization effect of HPM on S. aureus subsp. aureus was attributed to a significantly disrupted cell structure and increased membrane permeability, which led to the leakage of intracellular proteins, resulting in bacterial death. At the same time, HPM treatment was able to significantly reduce the ability of S. aureus subsp. aureus to form biofilms, which, in turn, reduced its virulence. Finally, compared to the simulated system, more effective sterilization was observed in apple juice, with its color and pH remaining unchanged, which suggested that HPM can be used to process other liquid foods.