Enzymatically Pretreated Red-Fleshed Pitaya (Hylocereus polyrhizus) as a Co-Fermentation Substrate Improves the Nutritional Quality and Sensory Profile of Black Rice Wine

Black rice wine is a traditional cereal-based fermented beverage valued for its colour, flavour and bioactive constituents. However, product innovation is needed to meet increasing consumer demand for fruit-derived aroma, nutritional quality and functional attributes. To address this demand, we developed an integrated processing strategy combining enzymatic pretreatment of pitaya pulp with stage-specific co-fermentation, an approach that has not been systematically evaluated in rice wine systems. Pitaya pulp was first pretreated with pectinase using an orthogonal design to optimise juice yield and betacyanin retention; the enzymatically pretreated pitaya pulp was then introduced either as pulp or as fermented pitaya wine at the saccharification, tank-flushing or ageing stage. The resulting wines were compared with a pitaya-free control and three commercial black rice wines on the basis of physicochemical indices, phenolic and pigment contents, amino acid composition, mineral composition and fuzzy mathematics-based sensory evaluation. Pitaya pulp added at saccharification (Sample THJ) yielded the strongest functional and nutritional profile, with the highest total phenolic content (629.74 mg/L); high flavonoid content (152.07 mg/L); enrichment in Mg, K and Mn; and a broader taste-active amino acid profile. By contrast, pitaya pulp added during tank flushing (Sample CHJ) achieved the highest sensory score (85.3) and had the highest anthocyanin content. These findings indicate that the timing and form of pitaya addition determine the balance between functional enrichment, pigment retention and sensory quality. Co-fermentation with red-fleshed pitaya, particularly the early addition of enzymatically pretreated pitaya pulp, provides a practical route for the development of fruit-flavoured black rice wine with improved nutritional composition and consumer appeal, suggesting the potential for enhanced functional value.