Nutritional composition, antioxidant potential, physical characteristics, overall acceptance, and <i>in vitro</i> glycaemic index of cookies fortified with rambutan (<i>Nephelium lappaceum L</i>.) seed powder

Abstract Rambutan seeds are a by-product of the fruit processing industry. In this research, wheat flour was partially replaced by rambutan seed powder in a cookie recipe and the influence of this replacement on the product quality was examined. When increasing the rambutan seed proportion and reducing the unsalted butter ratio in the cookie recipe, the lipid content was unchanged; the ash, dietary fibre, phenolic, and saponin contents of the product were significantly enhanced while the starch and protein contents gradually decreased. The use of rambutan seed powder slightly improved monounsaturated fatty acids level but reduced polyunsaturated fatty acids content in the cookies. At the proportion of 30% and 40% rambutan seed powder, the obtained cookies had lower hardness and breaking strength but greater overall acceptance than the control cookie. The partial replacement of wheat flour by rambutan seed powder efficiently decreased in vitro glycaemic index of the product.