Abstract

The development of functional yogurt products enriched with plant-derived ingredients and biologically active compounds represents a promising strategy to improve the nutritional, probiotic, and antioxidant properties of fermented dairy foods. The aim of this study was to evaluate how plant-derived ingredients (whole-meal flour from sprouted wheat grain and a protein-rich functional ingredient derived from hemp press cake), used individually or in combination with curcumin- or ergosterol-enriched Saccharomyces cerevisiae biomass, influence the physicochemical, structural-mechanical, probiotic, antioxidant, and sensory characteristics of yogurt products. Two forms of yeast biomass were used as enrichment agents: one containing encapsulated curcumin and the other with a high ergosterol content. Milk mixtures were supplemented with yeast biomass containing 34.0 mg/g encapsulated curcumin or 10.55 mg/g ergosterol. Additionally, whole-meal flour from sprouted wheat grain or the hemp-derived protein ingredient was incorporated into the yogurt products at concentrations of 2–3%. These ingredients were tested both individually and in combination to identify optimal formulations that would confer novel properties to the final products. Based on the conducted studies, it was found that the addition of enriched yeast biomass and the protein ingredient resulted in a denser and more uniform structure in the yogurt products compared to those of the control. The titratable acidity of the experimental formulations ranged from 80.2 to 91.8 °T, while pH values ranged from 3.79 to 4.04. Compared with the control sample, these changes indicate enhanced lactic acid fermentation activity. The number of probiotic microorganisms in the experimental samples reached 1.6 × 107–6.4 × 107 MPN/g, exceeding those of the control by an order of magnitude. The type of plant ingredient used significantly determined the technological properties of the finished product. Compared with the control sample, yogurt products supplemented with the hemp press cake-derived protein ingredient exhibited higher protein content (33–34% on a dry matter basis), increased viscosity (2.5–2.6 Pa·s), and reduced syneresis (values of 16.1 mL). The whole-meal flour from sprouted wheat grain exhibited a more pronounced stimulating effect on the growth of probiotic microflora. Enrichment of yogurt products with yeast biomass also increased antioxidant activity: the AOA (DPPH) value increased to 69–84% compared to ~62% in the control. Biotesting using Paramecium caudatum, a sensitive protozoan model widely used for rapid assessment of biological compatibility, toxicity, and the relative biological value of food systems, demonstrated a statistically significant increase (p < 0.05) in protozoan growth to 104–106% compared with the control sample, suggesting the absence of toxic effects and the potential bioavailability of yogurt matrix components. This data confirm the potential of using enriched yeast biomass in combination with plant ingredients for creating probiotic yogurt products with improved structural and functional properties.

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