Broken rice grains pregelatinized flours incorporated with lyophilized açaí pulp and the effect of extrusion on their physicochemical properties

Abstract

Liophilized açaí pulp (LAP), which is considered a power food, could enrich broken rice grains flours (BRG), which is an abundant by-product in many countries. The extrusion could change the physico-chemical properties of this mixture, which later could be applied in the development of instant food products, as an appeal regarding the appearance, nutritional value and the presence of bioactive compounds. This study examined the effect of LAP incorporation (0, 5, 10, 15, and 20%) on the physical, chemical, and functional properties of BRG pregelatinized flours at mild extrusion conditions. Extrusion significantly changed the solubility and absorption of water, the thermal and pasting properties of pregelatinized flours. DSC analysis did not show gelatinization peaks after extrusion, indicating a total gelatinization of the starch. Extrusion also affected the color and chemical composition, and to a greater extent, the anthocyanin content, the phenolic compounds and the antioxidant capacity, despite the mild process conditions. The mixture with 10% LAP resulted in a product with a reddish color, rich in fiber and presented lower loss of anthocyanin (27.16%), therefore, the most suitable to be used as an ingredient in the preparation of ready-to-eat foods with higher functional value.