Spontaneously fermented curly kale juice: Microbiological quality, nutritional composition, antioxidant, and antimicrobial properties

摘要

Nondairy fermented products, such as fruit and vegetable juices, are gaining popularity among consumers worldwide for health-related and economic reasons. The purpose of this study was to determine the changes in microbiological quality; antimicrobial and antioxidant activity; and phenolic, vitamin C, minerals, and cadmium content occurring during spontaneous fermentation of curly kale juice. The fermentation process contributed to a significant growth of lactic acid bacteria, enterococci, and yeasts, while no pathogens of Escherichia coli and Salmonella spp. were observed. The antimicrobial properties of the obtained juice improved during fermentation for all indicator microorganisms. Total phenolic content and antioxidant activity increased from 48 to 116 mg gallic acid equivalent/100 mL and from 4.5 to 6.8 mM Trolox/100 mL, respectively, while the content of vitamin C decreased. The results indicated that 100 mL ofjuice provided a significant contribution to the recommended mineral intake. Moreover, the content of heavy metal Cd was within acceptable limit (6 μg/kg). Overall, our findings indicate that fermented curly kale juice may become popular in the functional food sector, especially among vegetarians and consumers with lactose intolerance or allergy to milk proteins.