A novel antidiabetic lactofermented beverage from agro-industrial waste (broccoli leaves): Process optimisation, phytochemical characterisation, and shelf-life through thermal treatment and high hydrostatic pressure

Fermentation is the main process in several foods claimed to be health-promoting products due to their content in microorganisms and bioactive compounds. Therefore, in this study, the fermentation process was used to revalorise broccoli waste in the development and optimisation of a new fermented beverage by Lactiplantibacillus plantarum following a fermentation-assisted extraction strategy. The beverage was also subjected to several processing treatments and stored at 5 °C for 49 days. LC-MS/MS was used to characterise and quantify the individual (poly)phenolic and isothiocyanate contents. Optimised fermentation was carried out using a Box-Behnken design and the process was set to 4 days, 0.1 g of leaves per mL and 27.77 °C. Pasteurisation resulted in a higher (poly)phenolic content but caused a fall in LAB population to 3.5 log CFU/mL. In the control beverage, the (poly)phenol content decreased with increasing storage time and the LAB population was maintained at 6.5 log CFU/mL. In the beverage treated with high hydrostatic pressure (HHP 200 MPa, 10 min) the LAB population also remained like the control, maintained the stability of the phytochemical with the highest content of sulforaphane (4.38–8.82 mg/L), and a high stability of its antidiabetic potential during refrigeration. In contrast, the beverage subjected to HHP 400 MPa for 1 min had reduced LAB population (2 log CFU/mL), and obtained the lowest (poly)phenolic content, and α-amylase inhibition. In conclusion, the results suggest that HHP 200 MPa treatment was the most suitable method to achieve stability of LAB population and phytochemicals throughout the shelf-life.