Abstract
BACKGROUND: Lactic acid fermentation is a natural way to increase the bioactive and functional properties of fruit and vegetable juices. In this study, the in vitro gastrointestional digestion of phenolics, flavonoids, anthocyanins, and antioxidant activity of mixed vegetable juice was investigated as affected by fermentation with probiotic Lactobacillus plantarum and non-thermal treatments (ultraviolet (UV) and/or ultrasonic (US) treatment). For this purpose heat, US, UV or US/UV treated vegetable juice samples were fermented by probiotic L. plantarum and percentage recovery of bioactive (total phenolic (TPC), total flavonoid (TFC) and total anthocyanin contents (TAC) and antioxidant (DPPH [1,1-diphenyl-2-picrylhydrazyl] and CUPRAC [CUPric Reducing Antioxidant Capacity]) properties was evaluated during simulated gastrointestinal digestion. RESULTS: Total mesophilic aerobic bacteria (TMAB) and total yeast-mold (TYM) counts were significantly decreased by thermal and non-thermal processes and coliforms were fully eliminated. The bioaccessibility of total phenolics, anthocyanins, and flavonoids decreased after in vitro digestion. In general, recovery (5.78-34.71%) and serum availability of the bioactives was positively influenced by the fermentation and non-thermal treatments. Phenolics and anthocyanins exhibited the highest and the lowest recovery, respectively, while post-digestion recovery of antioxidant was between that of the phenolics and anthocyanins. CONCLUSIONS: This study confirmed that US and UV treatment could be advantageous alternatives to heat treatment for ensuring the microbial safety of vegetable juices with increased in vitro bioaccessibility of bioactive compounds while probiotic fermentation with L. plantarum contributed to the improvement of the bioactive profile. © 2021 Society of Chemical Industry.