Physicochemical Characteristics of a Novel Cereal-Based Food Material: Lactic Acid Fermented Grain Mixture
2023
Jang, K.H. | Surh, J.H.
This study employed the lactic acid fermentation process on a grain mixture (GM) composed of soybean, barley, brown rice, and wheat to formulate a novel cereal-based food material. Strains of lactic acid bacteria including Streptococcus lactis, Streptococcus thermophilus, and Lactobacillus acidophilus, along with Bifidobacterium longum KCTC 5734, were introduced into the GM. The mixture was cultivated aerobically at 37°C for 5 days, followed by freeze-drying to produce the fermented GM. Compared to the GM, the fermented GM exhibited decreased dietary fiber and protein-bound amino acid content, while there was an increase in soluble solids and free amino acid content. In addition, the pH decreased with an increase in titratable acidity. The total reducing capacity was ten-fold higher, and oxidation stability improved, as evidenced by the lower amounts of malondialdehyde under an accelerated oxidation system. These improvements could be attributed to the degradation of flavonoid glycosides into aglycone by the action of β-glucosidase in the microorganisms. The content of γ-aminobutyric acid and ornithine increased, while the content of glutamic acid and arginine, their precursor amino acids, decreased. These changes can be attributed to the action of glutamate decarboxylase of S. thermophilus and S. lactis, as well as arginine deiminase of S. lactis. The sedimentation index decreased, indicating better dispersibility. These results showed the potential of lactic acid fermentation when applied to mixed grains to develop novel food materials with unique functional attributes and physical characteristics that are distinctively different from those of the raw materials.
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