Less hawthorn leaf extract produced a better anti-browning effect when combined with ultrasound: a case study in fresh-cut potatoes

In the fresh-cutting industry, enzymatic browning poses a significant challenge. Although many anti-browning approaches have been evaluated individually, there are few combined technologies reported with the characteristics of health and low cost. To explore whether ultrasound (US) coupled with hawthorn leaf extract (HLE) could function as an effective anti-browning technology, this study was conducted. Results indicated that the combined treatment (US + 0.05% HLE) delayed the browning rate better than the individual application in fresh-cut potatoes stored at 4 °C for 8 d. Interestingly, the lower concentration combinations (US + 0.01% HLE) produced better anti-browning than that of their optimal combination (US + 0.05% HLE). Not only the activities of polyphenol oxidase, peroxidase, and phenylalanine ammonia-lyase, but also the content of phenolic, soluble quinones, intermediate, and advanced products were significantly diminished. Additionally, a decrease of malondialdehyde and H₂O₂, as well as lipoxygenase activity, and an increase in catalase, superoxide dismutase, and antioxidant capacity were achieved by the lower combination treatment. A Pearson correlation analysis revealed that all of the above detected parameters, except for phenylalanine ammonia-lyase, influenced browning development. Compared with the optimal combination, there is less accumulation of phenolic, and the intermediate and advanced products produced by the lower concentration combination. Thus, it is inferred the combination (US + 0.01% HLE) mediated the browning reaction and alleviated the reactive oxygen species (ROS)‒redox imbalance, which synergistically produced a superior quality. Overall, ultrasound coupling with a less dose extract (US + 0.01% HLE) is a more promising technology for discoloration control in the fresh cut industry.