Assessment of physical, microstructural, thermal, techno-functional and rheological characteristics of apple (Malus domestica) seeds of Northern Himalayas

In this research, two common apple seed cultivars Viz: ‘Golden Delicious’ (GD) and ‘Red Delicious’ (RD) of Northern Himalayan region were characterized for physical, techno-functional, microstructure, thermal, and rheological properties. Seeds showed a significant difference in width, arithmetic, and geometric mean diameters, volume, and surface area. Proximate analysis results revealed that seed flours have high oil content (> 20%) and are potentially rich sources of protein (> 40%). Color analysis of flours indicated their satisfactory whiter color with higher brightness values (L* ˃ 75), resulting from the reduced particle size which allows greater light penetration and relatively lower a* (< 1.5) and b* (< 11) values. Techno-functional attributes including water/oil absorption capacity, emulsifying capacity, and emulsion stability were significantly higher in RD than GD flour. There was also a significant difference in the average particle size of seed flours. Flour micrographs indicated the presence of oval/spherical-shaped starch granules embedded in dense protein matrix while, Differential Scanning calorimeter (DSC) revealed exothermic transition enthalpies for seed flours. Additionally, seed flours depicted high elastic modulus (G′), suggesting their suitability for modifying food texture. It was concluded that apple seeds exhibit significant potential for use in formulating protein-enriched foods while contributing to reducing industrial wastage.