Development of value-added tropical almonds (Terminalia catappa L.) and evaluation of physicochemical, sensory, nutritional and shelf-life properties

Tropical almond (Terminalia catappa L.) kernels are a highly nutritious yet underutilized resource in Sri Lanka, despite their rich content of protein, healthy lipids, minerals, and bioactive compounds. Limited consumer awareness, processing difficulties, and a lack of value-added products have hindered their commercial potential. This study was conducted to develop two value-added snack products: sugar-coated and savory tropical almonds, and to evaluate their nutritional, physicochemical, functional, and shelf-life characteristics under different packaging conditions. Sugar-coated almonds were formulated using 30%, 40%, and 50% (w/w) sugar levels, while savory almonds were developed using 5%, 7.5%, and 10% (w/w) spice mixtures. Sensory evaluation indicated that the formulation containing 40% (w/w) sugar in the sugar-coated almonds and 7.5% (w/w) spice in the savory almonds received the highest overall acceptability scores. Proximate analysis revealed that savory almonds had the highest protein (39.60 ± 1.87%), fat (78.00 ± 4.21%), and fiber (7.15 ± 0.65%), which was attributed to the composition of the coating mixture. Sugar-coated almonds exhibited a lower peroxide value (5.70 ± 0.64 meq/kg), indicating better oxidative stability. Among functional properties, sugar-coated almonds showed higher antioxidant activity (30.04 ± 3.46 mM Trolox/g) while savory almonds demonstrated the highest flavonoid content (4.13 ± 1.06 mg QE/g). Shelf-life evaluations were conducted over 12 weeks using paper zip-lock pouches and zip-lock pouches with an inner aluminium foil layer, with or without silica gel, to assess changes in color, moisture content, pH, water activity, and microbial growth. Results indicated that packaging with an inner aluminium foil layer, combined with silica gel, provided the best protection, maintaining product quality and minimizing microbial growth throughout storage. Overall, the study demonstrates that value addition through sugar-coated and savory tropical almond snacks can significantly improve the usability and marketability of this underexploited nut, offering promising opportunities for commercial production and rural entrepreneurship.