Potential of Homopolysaccharide-Producing Starter Cultures in the Fermentation of Coconut Yoghurt Alternatives...

This study investigates the use of a homopolysaccharide (HoPS)-producing Latilactobacillus sakei strain for the production of protein-enriched plant-based yoghurt analogues based on coconut milk. Formulations varied in added sucrose (2.5% or 5.0% w/w), pea protein isolate (PPI; 0-5.0% w/w), and tapioca starch (0%, 1.5% w/w), and were fermented with either a HoPS-producing strain (L. sakei 1.411), or a non-exopolysaccharide (EPS)-producing control strain (L. sakei 1.2037) with very similar acidification kinetics. Microbial growth and pH were monitored, HoPS content was determined via HPLC, and both firmness and syneresis were assessed during 5 days of storage at 4 °C. EPS yields were significantly higher (p < 0.05) in samples with 5.0% w/w added sucrose compared to those with 2.5% w/w. Fermentation with L. sakei 1.411 generally resulted in firmer gels (p < 0.05) and reduced syneresis (p < 0.05) compared to L. sakei 1.2307 and the enhanced viscosity (sample thickness) was also observed in a sensory analysis. Samples containing starch and 5.0% w/w PPI showed the highest firmness-related values. These findings demonstrate the potential of in situ HoPS production to improve the texture and stability of protein-enriched coconut-based yoghurt analogues. It highlights the importance of matrix formulation, strain selection and process control, which all contribute to the final product quality.