Processing-induced hydrolysis and degradation pathways of glucotropaeolin in edible garden nasturtium (Tropaeolum majus L.) extracts

Garden nasturtium ( Tropaeolum majus L. ) is a rich source of bioactive compounds, particularly glucotropaeolin, and is increasingly used in functional foods. Maintaining glucosinolate stability during processing is critical for ensuring consistent bioactivity. This study systematically investigated the kinetics and mechanism of glucotropaeolin degradation in edible extracts obtained from seeds, leaves, and flower buds under typical processing and storage conditions. Glucotropaeolin hydrolysis was primarily driven by myrosinase, producing benzyl isothiocyanate, which then degraded to form benzyl thiocarbamate and 1,3-dibenzyl-2-thiourea. Untreated or lyophilised extracts showed rapid glucotropaeolin degradation, whereas boiling-induced myrosinase inactivation substantially improved glucotropaeolin stability. Additionally, an analysis of commercial garden nasturtium extracts revealed surprisingly low levels of glucotropaeolin and benzyl isothiocyanate, highlighting the impact of industrial processing. These findings provide insight into the mechanism of glucotropaeolin stability and highlight processing strategies for preserving bioactive glucosinolates, supporting the development of functional foods with predictable bioactive profiles.