Biochemical composition and functional properties of pumpkin (Cucurbita sp.) seed yogurt: a functional plant-based product

• Pumpkin seed milk successfully fermented into functional plant-based yogurt. • High protein content with complete essential amino acids; threonine enriched. • Fermentation preserved oleic/linoleic acids and reduced saturated fatty acids. • Increased phenolics, FRAP, and DPPH; ABTS decline showed assay-specific effect. • SEM revealed dense gel network via protein–hydrocolloid–EPS interactions. • Viable LAB and Bifidobacterium more than 7 log CFU/g confirmed probiotic potential. This study developed a functional, plant-based yogurt from pumpkin seed milk and evaluated its biochemical, antioxidant, and microstructural properties. Fermentation with a commercial starter culture yielded a product with high viable cell counts of lactic acid bacteria (7.17 log CFU/g) and Bifidobacterium spp. (7.82 log CFU/g), confirming probiotic viability. The yogurt retained a high protein content (6.78 ± 0.04%) and a complete profile of essential amino acids, including elevated threonine levels, while reductions in tryptophan and histidine suggested microbial utilization during fermentation. Fatty acid profiling revealed reduced saturated fatty acids and preserved levels of oleic and linoleic acids, with implications for cardiovascular health. Antioxidant properties were enhanced, as shown by increased total phenolic content (TPC; 73.20 ± 0.70 mg GAE/L), ferric reducing antioxidant power (FRAP; 149.16 ± 0.73 µmol Trolox/L), and DPPH (2,2-diphenyl-1-picrylhydrazyl) activity. By contrast, ABTS (2,2′-azinobis (3-ethylbenzothiazoline-6-sulfonic acid)) activity decreased, reflecting assay-specific behavior. Scanning electron microscopy revealed a dense, cohesive gel network in the fermented yogurt, attributed to protein hydrolysis, exopolysaccharide formation, and protein-polysaccharide interactions. These compositional and structural changes supported the potential of pumpkin seed yogurt as a nutrient-dense, dairy-free alternative with functional health benefits. The clean-label formulation, enhanced microstructure, and probiotics viability underscored its relevance in sustainable plant-based food innovation.