Fermented Plant-Based Milks: Effects of pH Value and Storage Conditions on Protein Stability

Introduction

The growing demand for plant-based dairy alternatives has accelerated the development of fermented plant-based milks. Protein stability is one of the most important quality factors that affects texture, shelf life, and consumer acceptability. Although soy and oat milks are frequently used in various formulations, their protein systems are sensitive to changes in temperature and pH value. This study aims to investigate how pH adjustments and storage temperatures affect protein stability in fermented soy and oat milks.

Methods

Commercial soy and oat milks were inoculated with a starter culture containing Lactobacillus spp. and incubated at 37 ^°C for 12–24 hours to initiate fermentation. Before inoculation, selected samples were adjusted to specific pH levels ranging from 4.5 to 6.5 to evaluate the impact of initial acidity. Following fermentation, all samples were kept for a maximum of 10 days at 25 ^°C and 4 ^°C. Protein stability was assessed by sedimentation analysis, and total protein content was measured using the Kjeldahl method.

Results

Preliminary results indicate that samples adjusted to lower pH values (around 4.5–5.0) and stored at 4 ^°C exhibited significantly improved protein stability, with reduced sedimentation and better protein retention. In contrast, storage at 25 ^°C led to increased sediment formation and protein destabilization, especially in samples with higher initial pH values.

Conclusions

The results highlight the importance of both pH value adjustment and cold storage in preserving protein stability in fermented plant-based milks. These findings provide useful insights for optimizing formulation and storage strategies, ultimately supporting the development of higher-quality plant-based dairy alternatives.