Comparing the effect of several pretreatment steps, selected to steer (bio)chemical reactions, on the volatile profile of leek (Allium ampeloprasum var. porrum)

Abstract

Volatile compounds in foods can witness the occurrence of (bio)chemical reactions, comprising both enzymatic and non-enzymatic reactions, which can be influenced by processing. This study investigated the effect of different pretreatments aimed at either minimizing, realized by a heat treatment, or inducing, realized by a tissue disruptive treatment, enzymatic reactivities, on the volatile profile of leek. The volatile profiles obtained were then linked to possible (bio)chemical reactions that could have occurred during the treatments. The study showed that different pretreatments led to markedly different volatile profiles, characterized by different (abundances of) volatile compounds. Partial and extensive tissue disruption was achieved by pulsed electric fields at low electric field strength and mixing, respectively. After these tissue disruptive treatments, the volatile compounds could mainly be related to the occurrence of several enzyme-substrate interactions, including conversions of alk(en)yl cysteine sulfoxides by alliinase and of unsaturated fatty acids by lipoxygenase and hydroperoxide lyase. Thermally-induced reactions were also observed to impact the resultant volatile profile. Present study revealed that targeted (pre)treatment allows to steer (bio)chemical reactions towards specific volatile compounds in leek products.