High hydrostatic pressure inactivation of microorganisms: A probabilistic model for target log-reductions

Effects of high-pressure processing on the physicochemical properties and glycemic index of fruit puree in a hyperglycemia mouse model

BACKGROUND

In this study, the duration of high-pressure processing (HPP) required to achieve a 5 log reduction of Escherichia coli O157:H7 in fruit purees was evaluated. Banana, cantaloupe, and dragon fruit purees were subjected to HPP at 600 MPa for 300, 270, and 270 s, respectively, and their physicochemical properties and enzyme activities were then analysed. Diabetic mice were fed fresh and HPP-treated purees to observe their effects on the glycemic index (GI) and postprandial blood glucose response.

RESULTS

Compared with their fresh counterparts, the HPP-treated banana and dragon fruit purees exhibited significantly higher viscosities, lower glucose concentrations, and higher glucose dialysis retardation indices and showed disrupted sucrose invertase and polygalacturonase activities. The GI and postprandial blood glucose response were not significantly different between the fresh and HPP-treated cantaloupe purees. By contrast, the peak time of glucose response (T_max ) was delayed from 30 min to 60 min, and the area under the receiver operating characteristic curve was reduced by 40% in the mice fed HPP-treated banana and dragon fruit purees. The GIs of the HPP-treated banana and dragon fruit purees (were 50.3 and 44.8, respectively) were significantly lower than those of their fresh counterparts (85.1 and 75.2, respectively).

CONCLUSION

HPP can change the physicochemical properties of fruit purees, resulting in stabilized blood glucose levels and lower GIs after consumption. Therefore, purees processed in this manner would benefit consumers and patients with diabetes/pre-diabetes who need to maintain stable blood glucose levels (Fig. S1). © 2022 Society of Chemical Industry.

Evaluation of microbiological safety, physicochemical and aromatic qualities of shiikuwasha (Citrus depressa Hayata) juice after high pressure processing

This study evaluated high pressure processing (HPP) for achieving greater than 5-log reduction of Escherichia coli O157:H7 in shiikuwasha (Citrus depressa Hayata) juices and compare quality parameters, including microbiological safety, total phenolic content (TPC), total flavanones (TFC), and polymethoxylated flavones, browning, volatile aromatic, and physicochemical properties of HPP-treated juice with those of high-temperature short-time pasteurized juice. A HPP of 600 MPa for 150 s was identified capable of achieving greater than 5.15-log reductions of E. coli O157:H7 in shiikuwasha juice. The microbiological shelf life of the juices were at least 28 days when processed at HPP for 600 MPa/150 s or HTST for 90 °C/60 s. The color, aromatic, and antioxidant contents (TPC, TFC, Tangeletin, Nobiletin) were well preserved after HPP, however, HTST resulted in a significant (p < 0.05) loss of antioxidant content (TPC (8.8%), Tangeletin (6.8%)), and negatively impacted the juice color. By the end of storage, the amount of these aroma relevant volatiles appears to still be higher in HPP pasteurized juices compared to their conventional counterparts. This study demonstrated that under optimal conditions of HPP can attain the same level of microbiological safety as thermal pasteurization and preserved the acceptable quality of shiikuwasha juice.