Black Gram ( <scp> <i>Vigna mungo</i> </scp> L.) Hull as a Source of Soluble Dietary Fiber: Preparation and Application in Chocolate Cake With Lowering Glycemic Index

ABSTRACT Black gram hull (BGH), by‐product from a sprouting process, is a source of soluble dietary fiber (SDF) with bioactivity, making it an interesting ingredient for development of food products with health‐promoting effect. This research aims to examine the effect of alkaline‐aided extraction (0.5%, 1%, and 2% NaOH solutions) on physicochemical properties and bioactivity of the SDF from BGH, before employing the SDF in a model food with health‐promoting effect. The SDF recovered using 1% NaOH solution (SDF‐1) possessed good thermal stability along with effective bioactivities involving antioxidant activity, α‐glucosidase inhibition effect, and abilities to absorb cholesterol, bile salt, and nitrite. These effects might be postulated to occur due to a suitable concentration of the alkaline solution to liberate the fiber with appropriate physical and chemical characteristics. Then, the SDF‐1 was used to replace wheat flour at varying levels for chocolate cake preparation. The starch digestibility and estimated glycemic index were lowered when the SDF‐1 was incorporated into the cakes, especially at the increased fiber content. This suggested the possibility of the SDF‐1 as a functional ingredient to produce food with health‐promoting effect related to blood sugar homeostasis.