Sequential autoclave-hydrothermal, enzymatic conversion of cauliflower waste Xylan into high-purity bioactive Xylooligosaccharides: Purification, prebiotic activity and toxicity analysis.

The sustainable valorization of food wastes into health-promoting products as prebiotic xylo-oligosaccharides (XOS) is surely a circular bioeconomy initiative. This study reports autoclave-hydrothermal pretreatment (AC-PT) for superior 71.7% xylan recovery from cauliflower waste. The optimized enzymatic hydrolysis of xylan produced 64.27% XOS, primarily X2 (38.4%), X3 (24.9%), X4 (34.3%) and X6 (2.4%). The sequential ultra- and nano-purification primarily purified the XOS fractions, X2 (55.8%), X3 (35.7%), X4 (8.3%) and X6 (0.2%). The purified XOS showed a good prebiotic effect, promoting the growth of Lactobacillus strains with a > 1 prebiotic index, prebiotic score and good antimicrobial activity. In-vitro XOS fermentation generated lactic acid and SCFAs. The cytotoxicity of XOS exhibited no plant toxicity or cytotoxicity on NCM 460 human cell lines. This work confirms the practical applicability of sequential autoclave hydrothermal pretreatment-enzymatic hydrolysis-membrane purification from cauliflower waste as high-quality prebiotics.