A comprehensive nutritional profiling of rubber seed powder: evaluating the impact of shell inclusion and implications for future dietary applications

Rubber (Hevea brasiliensis) seeds, which have traditionally been underutilized, are gaining attention for their rich nutritional and bioactive properties. This study offers a comprehensive comparison of the proximate, fatty acid, mineral, heavy metal, and amino acid content of rubber seed powder with (S1) and without (S2) the shell. Proximate analysis demonstrated that shell removal significantly enhances key nutrients (p < 0.05), with protein content increasing from 9.82 % in S1 to 16.11 % in S2, and fat content rising from 21.38 % to 38.39 %. The carbohydrate content showed a similar pattern, decreasing in S2, which highlights an improved macronutrient balance. The de-shelled seeds (S2) exhibited higher concentrations of potassium (7.77 mg/100 g) and phosphorus (6.92 mg/100 g) compared to S1, indicating a superior mineral profile. Amino acid profiling further substantiated this improvement, with essential amino acids such as glutamine increasing from 14.71 µg/mg in S1 to 48.93 µg/mg in S2 (p < 0.05), suggesting enhanced protein quality after shell removal. Furthermore, significantly elevated levels of total flavonoid content (2.4-fold), total phenolic content (1.81-fold), and total antioxidant activity (2.2-fold) in S2 reflect its enhanced antioxidant potential. The fatty acid profile of S2 also showed notable increases in beneficial unsaturated fatty acids, particularly linoleic acid, though some fatty acids like oleic acid were slightly reduced. These findings underscore that shell removal significantly improves the nutritional, bioactive, and antioxidant properties of rubber seed powder, with substantial differences in mean values (p < 0.05), positioning de-shelled rubber seeds as a potent functional food ingredient. In addition, safety concerns related to heavy metal and anti-nutrient factors contamination are adequately addressed.