Presentation Information
[P02-916]Synergistic Effects of Homo- and Heterofermentative Probiotics on the Metabolomic and Textural Profiles of Soy Yogurt
○So-Young Yim1、Nam Soo Han1 (1. Chungbuk National University (Korea))
Keywords:
soy yogurt,LAB co-fermentation,texture (viscosity,WHC),flavor (diacetyl,hexanal),metabolomics (GC-MS,NMR)
[Purpose]
Plant-based dairy alternatives like soy yogurt are rapidly growing in the food industry, but undesirable beany off-flavors and poor textural properties often limit consumer acceptance. This study aimed to overcome these limitations by evaluating the effects of mixed-culture composition and ratio optimization on the physicochemical and fermentation characteristics of soy yogurt. Three previously selected strains were utilized: Limosilactobacillus fermentum EFEL6805 (LBF, obligately heterofermentative), Limosilactobacillus reuteri EFEL6901 (LBRE, obligately heterofermentative), and Streptococcus thermophilus (STT, homofermentative).
[Method]
Sterilized soymilk was fermented with various single and mixed cultures. Based on a 1:1:1 basic ratio, five combinations (ranging from 1:5.5:5.5 to 10:1:1) were fermented at 37 °C for 24 h. Physicochemical properties (pH, acidity, viscosity, water-holding capacity [WHC]), texture profiles, and sensory attributes were evaluated, alongside comprehensive metabolite profiling via GC-MS and 1H-NMR.
[Results]
The results indicated that mixed cultures containing LBF formed smaller, smoother, and more uniform curd particles compared to single cultures. Rheological analysis revealed that the three-strain mixture (LBF+LBRE+STT) exhibited the highest WHC and viscosity. Principal Component Analysis (PCA) of 1H-NMR data confirmed distinct fermentation patterns between homofermentative and heterofermentative strains. Crucially, a direct correlation between precursor consumption and volatile flavor production was established; samples with lower residual citrate, driven primarily by STT, showed significantly higher concentrations of desirable dairy-like flavor compounds such as diacetyl and acetoin.
[Consideration]
As the proportion of STT increased in the ratio trials, overall acidity and creamy flavors were enhanced. Conversely, higher proportions of LBF and LBRE effectively reduced beany off-flavors, including hexanal and heptanal. The co-fermentation of heterofermentative and homofermentative strains resulted in a synergistic increase in acetic acid, as well as phenolic and sweet-related volatile compounds. Furthermore, 1H-NMR analysis revealed that while most amino acids decreased after fermentation, the concentrations of lysine, proline, serine, and threonine significantly increased.
[Conclusion]
In conclusion, co-fermentation with LBF, LBRE, and STT effectively reduced off-flavors while significantly improving the flavor balance and texture of soy yogurt. Among the tested ratios, the range of 2:5:5 to 5:3:3 was identified as the optimal condition, yielding a premium product with a well-balanced sensory and metabolic profile.
Plant-based dairy alternatives like soy yogurt are rapidly growing in the food industry, but undesirable beany off-flavors and poor textural properties often limit consumer acceptance. This study aimed to overcome these limitations by evaluating the effects of mixed-culture composition and ratio optimization on the physicochemical and fermentation characteristics of soy yogurt. Three previously selected strains were utilized: Limosilactobacillus fermentum EFEL6805 (LBF, obligately heterofermentative), Limosilactobacillus reuteri EFEL6901 (LBRE, obligately heterofermentative), and Streptococcus thermophilus (STT, homofermentative).
[Method]
Sterilized soymilk was fermented with various single and mixed cultures. Based on a 1:1:1 basic ratio, five combinations (ranging from 1:5.5:5.5 to 10:1:1) were fermented at 37 °C for 24 h. Physicochemical properties (pH, acidity, viscosity, water-holding capacity [WHC]), texture profiles, and sensory attributes were evaluated, alongside comprehensive metabolite profiling via GC-MS and 1H-NMR.
[Results]
The results indicated that mixed cultures containing LBF formed smaller, smoother, and more uniform curd particles compared to single cultures. Rheological analysis revealed that the three-strain mixture (LBF+LBRE+STT) exhibited the highest WHC and viscosity. Principal Component Analysis (PCA) of 1H-NMR data confirmed distinct fermentation patterns between homofermentative and heterofermentative strains. Crucially, a direct correlation between precursor consumption and volatile flavor production was established; samples with lower residual citrate, driven primarily by STT, showed significantly higher concentrations of desirable dairy-like flavor compounds such as diacetyl and acetoin.
[Consideration]
As the proportion of STT increased in the ratio trials, overall acidity and creamy flavors were enhanced. Conversely, higher proportions of LBF and LBRE effectively reduced beany off-flavors, including hexanal and heptanal. The co-fermentation of heterofermentative and homofermentative strains resulted in a synergistic increase in acetic acid, as well as phenolic and sweet-related volatile compounds. Furthermore, 1H-NMR analysis revealed that while most amino acids decreased after fermentation, the concentrations of lysine, proline, serine, and threonine significantly increased.
[Conclusion]
In conclusion, co-fermentation with LBF, LBRE, and STT effectively reduced off-flavors while significantly improving the flavor balance and texture of soy yogurt. Among the tested ratios, the range of 2:5:5 to 5:3:3 was identified as the optimal condition, yielding a premium product with a well-balanced sensory and metabolic profile.
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