# Controlling Off-Odors in Plant Proteins Using Sequential Fermentation

## TL;DR

This study introduces a two-stage fermentation method to reduce unpleasant odors in plant-based proteins, making them more appealing to consumers.

## Contribution

A novel sequential fermentation strategy using specific microbes to significantly reduce off-odors in plant proteins.

## Key findings

- Two-stage fermentation reduced key odorants like hexanal and sulfur compounds by 95–99% across eight plant proteins.
- Sequential fermentation outperformed single-stage methods in deodorization effectiveness.
- Additives like allulose and strawberry preserves enhanced microbial activity without negatively affecting volatile profiles.

## Abstract

Off-odors produced by volatile compounds remain a major barrier to consumer acceptance of plant-based proteins. This study presents a novel two-stage fermentation strategy to effectively reduce undesirable volatiles in eight plant proteins. A sequential fermentation process was developed using Lactobacillus plantarum in Stage 1 and a traditional yogurt culture, Streptococcus thermophilus, Lactobacillus delbrueckii subsp. Bulgaricus and Lactobacillus acidophilus, in Stage 2. This method was applied to solutions of 9% soy, pea, chickpea, mung bean, faba bean, rice, barley-rice, and hemp proteins. Volatile profiles were analyzed via Selected Ion Flow Tube Mass Spectrometry (SIFT-MS) and sensory evaluation before and after fermentation. The two-stage fermentation resulted in significant deodorization, with 95–99% reduction in key odorants such as hexanal, 2-pentylfuran, methoxypyrazines, and sulfur compounds across all proteins. The sequential approach significantly outperformed a one-stage fermentation. Allulose enhanced L. plantarum activity while strawberry preserves supported traditional yogurt culture performance. Non-fermentable additives such as pectin, xanthan gum, and oil had minimal effects on volatiles. The proposed fermentation method offers an effective, scalable, and clean-label solution for mitigating off-odors in plant-based proteins. By leveraging microbial metabolism and formulation synergies, this strategy provides a foundation for developing more palatable plant-based dairy alternatives.