To overcome texture and flavor challenges in fermented plant-based product development, the potential of microorganisms is generating great interest in the food industry. This study examines the effect of Lactobacillus rhamnosus on physicochemical properties of fermented soy, oat, and coconut. L. rhamnosus was combined with different lactic acid bacteria strains and Bifidobacterium. Acidification, titratable acidity, and viability of L. rhamnosus and Bifidobacterium were evaluated. Oscillation and flow tests were performed to characterize rheological properties of fermented samples. Targeted and untargeted volatile organic compounds in fermented samples were assessed, and sensory evaluation with a trained panel was conducted. L. rhamnosus reduced fermentation time in soy, oat, and coconut. L. rhamnosus and Bifidobacterium grew in all fermented raw materials above 107 CFU/g. No significant effect on rheological behavior was observed when L. rhamnosus was present in fermented samples. Acetoin levels increased and acetaldehyde content decreased in the presence of L. rhamnosus in all three bases. Diacetyl levels increased in fermented oat and coconut samples when L. rhamnosus was combined with a starter culture containing Streptococcus thermophilus and with another starter culture containing S. thermophilus, L. bulgaricus and Bifidobacterium. In all fermented oat samples, L. rhamnosus significantly enhanced fermented flavor notes, such as sourness, lemon, and fruity taste, which in turn led to reduced perception of base-related attributes. In fermented coconut samples, gel firmness perception was significantly improved with L. rhamnosus. The findings suggest that L. rhamnosus can improve fermentation time and sensory perception of fermented plant-based products.

The production of a fermented plant-based cheese requires understanding the behavior of the selected raw material prior to fermentation. Raw material processing affects physicochemical properties of plant protein ingredients, and it determines their ability to form fermentation-induced protein gels. Moreover, the addition of oil also influences structure formation and therefore affects gel firmness. This study focuses on identifying and characterizing an optimal pea protein matrix suitable for fermentation-induced plant-based cheese. Stability and gel formation were investigated in pea protein matrices. Pea protein isolate (PPI) emulsions with 10% protein and 0, 5, 10, 15, and 20% olive oil levels were produced and further fermented with a starter culture suitable for plant matrices. Emulsion stability was evaluated through particle size, ζ-potential, and back-scattered light changes over 7 h. Gel hardness and oscillation measurements of the fermented gels were taken after 1 and 7 days of storage under refrigeration. The water-holding capacity of the gels was measured after 7 days of storage and their microstructure was visualized with confocal microscopy. Results indicate that all PPI emulsions were physically stable after 7 h. Indeed, ζ-potential did not change significantly over time in PPI emulsions, a bimodal particle size distribution was observed in all samples, and no significant variation was observed after 7 h in any of the samples. Fermentation time oscillated between 5.5 and 7 h in all samples. Higher oil content led to weaker gels and lower elastic modulus and no significant changes in gel hardness were observed over 7 days of storage under refrigeration in closed containers. Water-holding capacity increased in samples with higher olive oil content. Based on our results, an optimal pea protein matrix for fermentation-induced pea protein gels can be produced with 10% protein content and 10% olive oil levels without compromising gel hardness.

Texture and flavor are currently the main challenges in the development of plant-based dairy alternatives. To overcome them, the potential of microorganisms for fermentation of plant-based raw materials is generating great interest in the food industry. This study examines the effect of Lactobacillus rhamnosus, LGG® (LGG® is a trademark of Chr. Hansen A/S) on the physicochemical properties of fermented soy, oat, and coconut. LGG® was combined with different lactic acid bacteria (LAB) strains and Bifidobacterium, BB-12® (BB-12® is a trademark of Chr. Hansen A/S). Acidification, titratable acidity, and growth of LGG® and BB-12® were evaluated. Oscillation and flow tests were performed to analyze the rheological properties of fermented samples. Acids, carbohydrates, and volatile organic compounds in fermented samples were identified, and a sensory evaluation with a trained panel was conducted. LGG® reduced fermentation time in all three bases. LGG® and BB-12® grew in all fermented raw materials above 107 CFU/g. LGG® had no significant effect on rheological behavior of the samples. Acetoin levels increased and acetaldehyde content decreased in the presence of LGG® in all three bases. Diacetyl levels increased in fermented oat and coconut samples when LGG® was combined with YOFLEX® YF-L01 and NU-TRISH® BY-01 (YOFLEX® and NU-TRISH® are trademarks of Chr. Hansen A/S). In all fermented oat samples, LGG® significantly enhanced fermented flavor notes, such as sourness, lemon, and fruity taste, which in turn led to reduced perception of the attributes related to the base. In fermented coconut samples, gel firmness perception was significantly improved in the presence of LGG®. These findings suggest supplementation of LAB cultures with LGG® to improve fermentation time and sensory perception of fermented plant-based products.

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