Effect of Homogenization and Pectin on Chemical, Textural, Antioxidant and Sensory Characteristics of L. bulgaricus-Fermented Oat-Based Product

Abstract

The demand for plant-based fermented beverages is being driven by dietary restrictions, health concerns, and environmental concerns. However, the use of plant substrates, such as oats, presents challenges in terms of fermentation and texture formation. The effects of enzymatic hydrolysis, homogenization and the addition of 1% pectin on oat-based beverages fermented with Lactobacillus delbrueckii subsp. bulgaricus were evaluated in this study. The samples were evaluated for a number of characteristics, including physicochemical, rheological, antioxidant and sensory properties. After 6 h fermentation, pectin-containing samples showed a statistically significant decrease in pH (to 3.91) and an increase in titratable acidity (to 92 °T). Homogenization and the addition of pectin were found to significantly increase viscosity (by 1.5-2 times) and water-holding capacity (by 2 times) while reducing syneresis by 96%. The antioxidant activity of L. bulgaricus-fermented samples increased significantly: the radical scavenging activity (RSA) and OH-radical inhibition increased by 40-60%, depending on the treatment. Extractable polysaccharides (PSs) inhibited lipase and glucosidase by 90% and 85%, respectively; significantly higher inhibition was observed in the fermented and pectin-containing groups. Sensory evaluation showed that the homogenized, pectin-enriched samples (Homog+) scored highest for consistency (4.5 ± 0.2), texture (4.9 ± 0.2), and overall acceptability (4.8 ± 0.2); these scores were all statistically higher than those for the untreated samples. These results suggest that combining enzymatic hydrolysis, homogenization and fermentation with L. bulgaricus significantly improves the structural, functional and sensory properties of oat-based beverages, providing a promising approach to producing high-quality, functional non-dairy products.

Keywords: antioxidants; fermentation; lactic acid bacteria; oat-fermented base; plant beverages; sensory evaluation; texture; viscosity.

Figure 1

The theoretical basis for the selection of oat-fermented base for plant beverages.

Figure 2

The experimental sample preparation.

Figure 3

The effects of varying the duration of fermentation and stabilization on changes in titratable acidity, pH (A,B) and glucose concentration (C,D). (A,C) Fermentation for 6 h; (B,D) fermentation for 24 h.

Figure 3

The effects of varying the duration of fermentation and stabilization on changes in titratable acidity, pH (A,B) and glucose concentration (C,D). (A,C) Fermentation for 6 h; (B,D) fermentation for 24 h.

Figure 4

Effect of L. bulgaricus fermentation and pectin on titratable acidity (A), pH (B), and absolute glucose concentration (C). Asterisks indicate statistically significant differences between variants without pectin and with pectin according to non-parametric one-way analysis of variance (Kruskal–Wallis) test, p < 0.05.

Figure 5

Viscosity changes during 6 h L. bulgaricus fermentation and after stabilization at 4 °C.

Figure 6

Effect of homogenization and pectin added to concentration on total phenol-containing compounds (TPCs) ((A)—product; (B)—protein-free extract) and peptides in protein-free extract (C) in L. bulgaricus-fermented oat base. Control—unfermented oat base, Control_h—unfermented homogenized oat base, Unhomog—L. bulgaricus-fermented oat base, Homog—L. bulgaricus-fermented homogenized oat base. Asterisks indicate statistically significant differences between variants without pectin (control) and with pectin according to non-parametric one-way analysis of variance (Kruskal–Wallis) test, p < 0.05.

Figure 7

Antioxidant activity of L. bulgaricus-fermented oat base: radical scavenging ability (A), OH-free radical scavenging ability (B), ferric reducing antioxidant power (C), and correlation (D); Control—unfermented oat base, Control_h—unfermented homogenized oat base, Unhomog—L. bulgaricus-fermented oat base, Homog—L. bulgaricus-fermented homogenized oat base. Asterisks indicate statistically significant differences between variants without pectin (control) and with pectin according to non-parametric one-way analysis of variance (Kruskal–Wallis) test, p < 0.05. “*”—indicates differences between versions with and without pectin. “**”—indicates differences between control (before fermentation) and after fermentation by L. bulgaricus.

Figure 8

Total amount of extractable polysaccharides (PSs) (A), radical scavenging ability (B), OH-free radical scavenging ability (C), lipase inhibition (D), glucosidase inhibition (E) of EPS extractable from L. bulgaricus-fermented oat base. Control—unfermented oat base, Control_h—unfermented homogenized oat base, Unhomog—L. bulgaricus-fermented oat base, Homog—L. bulgaricus-fermented homogenized oat base. Asterisks indicate statistically significant differences between variants without pectin (control) and with pectin according to non-parametric one-way analysis of variance (Kruskal–Wallis) test, p < 0.05. “*”—indicates differences between versions with and without pectin. “**”—indicates differences between variants without homogenization and with homogenization.

Figure 9

The heatmap correlation of sensory profile and chemical/texture parameters (A) of oat-based beverages fermented by L. bulgaricus with/without pectin and the principal component analysis of beverages (B).