# The Impact of Varying Enzymatic Pretreatment Durations of Wheat Gluten on the Flavour Characteristics of High-Moisture Plant-Based Extrudates

## TL;DR

This study shows that enzymatic pretreatment of wheat gluten for 40 minutes optimizes flavor in plant-based extrudates by enhancing umami and sweetness while reducing off-flavors.

## Contribution

The study identifies optimal enzymatic pretreatment duration and six key volatile compounds for flavor regulation in high-moisture plant-based extrudates.

## Key findings

- Moderate enzymatic pretreatment (40 min) maximized sensory scores and enhanced umami and sweetness.
- Extended pretreatment reduced beany off-flavors and increased meaty aroma compounds like furans and pyrazines.
- Excessive pretreatment (>40 min) led to burnt odors due to pyrazine accumulation, reducing flavor acceptance.

## Abstract

This study examined the effects of varying enzymatic pretreatment durations (0–80 min) of wheat gluten on flavour characteristics of high-moisture plant-based extrudates (HMPEs). Through a comprehensive analysis involving sensory evaluation, electronic tongue, free amino acid (FAA) profiling, electronic nose, and headspace solid-phase microextraction-gas chromatography-mass spectrometer (HS-SPME-GC-MS) analysis of volatile odour compounds, it was found that HMPEs with moderate enzymatic pretreatment (40 min) achieved the highest overall sensory score. Electronic tongue and FAA results confirmed a significant enhancement in umami and sweetness, while electronic nose effectively discriminated differences in odour profiles. Extending pretreatment durations gradually reduced beany off-flavours substances (hexanal reduced by up to 174.7 μg/kg) and encouraged the formation of meaty aroma compounds (furans and pyrazines). However, excessive pretreatment (>40 min) reduced acceptance due to burnt odour caused by the excessive accumulation of pyrazines, particularly 2,3-diethyl-5-methylpyrazine. Six key volatile odour compounds were identified by integrating the analysis of variable importance projection (VIP ≥ 1) and relative odour activity value (ROAV ≥ 1), offering a foundation for targeted flavour regulation in HMPEs.