Alginate and malva nut gum-based hydrogels incorporated with brewer’s spent grain as a source of fibre and antioxidants

Abstract

Hydrogels were prepared using malva nut gum (MVG) and alginate as a structuring agent via the ionotropic gelation method. For preparation as a source of fibre and antioxidant, the hydrogels were incorporated with brewer’s spent grain (BSG) at varying concentrations (0 - 10%). Then, the characteristics and stability of the beads were evaluated based on heating and the storage pH of the beads. The antioxidant activities of the hydrogels increased proportionally with the BSG content. The incorporation of BSG, especially at high concentration, enhanced the bead stability with the beads showing good stability under acidic pH conditions, perhaps because of molecular interactions between the hydrogel-structuring agents and the chemicals available in BSG, as suggested by the FTIR profiles. Then, the hydrogels incorporated with BSG were introduced to passionfruit juice, and their stability was observed throughout 2 w storage. The most appropriate BSG concentration incorporated into the beads was 7.5%, based on its good stability in the juice model, and the relatively high antioxidant capacity of the beads. Therefore, it could be feasible to use the MVG-alginate-based hydrogels incorporated with BSG for the production of healthy food, due to the presence of fibre and the antioxidant in the beads.