Impact of frozen storage and pretreatment conditions on health-related compound stability kinetics in leeks and Brussels sprouts

Abstract

Frozen vegetable chain variables can impact health-related compounds and their corresponding unique (bio)chemical reactions. To delve into this dynamism, kinetic shelf life studies were undertaken, focusing on several compounds (vitamin C, vitamin K1, carotenoids, glucosinolates, S-alk(en)yl-L-cysteine sulfoxides (ACSOs)) present in Brussels sprouts and leek. Frozen storage was conducted after industrial freezing and performed at −7, −15, −20 and −40 °C over one year. Glass transition temperature was about −24 °C for leek (Tg’) and about −27 °C for Brussels sprouts (Tg”). Overall, compound stability was higher when stored close to the glass transition temperature, influenced by (bio)chemical conversations related to substrate-enzyme location. Losses of 0–30% glucosinolates, 17–100 % vitamin C in blanched Brussels sprouts and 7–80% ACSOs, 87–100% vitamin C, 39–100% carotenoids in unblanched diced leeks were determined. Mathematical models were used to describe and compare the stability of these compounds as impacted by frozen storage. Additionally, different pretreatments (blanching, pureeing) were applied before freezing. Pretreatment type impacted initial compound concentrations, but had no impact on compound behavior during frozen storage of nine months, except for vitamin C which was stabilized by blanching but destabilized by pureeing. Overall, vitamin K1 was the only compound not impacted by storage temperature or pretreatment type.