Balancing flavor and bioactivity: fermentation-driven glucosinolate hydrolysis and sulforaphane stability in cruciferous vegetables

Cruciferous vegetables are rich in glucosinolates (GSLs) with diverse R-group side chains. Hydrolysis of GSLs yields various isothiocyanates (ITCs), including sulforaphane (SFN), which possesses anti-cancer and antioxidant activities. However, the pungent odor of SFN limits consumer acceptance. Probiotic fermentation effectively improves flavor and nutritional value. Single-strain fermentation may result in relatively monotonous flavors, whereas co-fermentation enriches flavor but may impair SFN stability. Microbial metabolism in co-fermentation can disrupt SFN-stabilizing acidic conditions and accelerate its degradation. Nevertheless, major research gaps still exist, including unclear microbial interactions in co-fermentation systems and bottlenecks for industrial-scale application. Based on GSL hydrolysis mechanisms, this review systematically compares single-strain and co-fermentation in terms of flavor and SFN content, and analyzes the mechanisms by which these two approaches improve the flavor of SFN-rich cruciferous vegetable juices. Furthermore, to quantify functional and flavor attributes under different fermentation processes and optimize product quality, we systematically summarize conventional and advanced detection techniques for flavor compounds and SFN. Meanwhile, the association between probiotic biotransformation and sensory quality in SFN-rich systems is specifically discussed, aiming to offer theoretical reference and practical insights for the quality improvement and product development of fermented cruciferous vegetable beverages.