Use of almond shell as food ingredient

Abstract

Almond shell is a major waste from the almond processing industry. Its feasibility as natural source of health-promoting components was examined. The by-product was fractionated under basic conditions following an easy scale-up process. The chemical composition of the recovered fraction and its antioxidant and antidiabetic properties were evaluated. Novel information regarding the chemical composition of the polysaccharides was also obtained. Almond shell is formed by lignin-carbohydrate complexes possessing antioxidant properties and capacity to inhibit α-glucosidase. According to our knowledge, this is the first time α-glucosidase inhibitory activity of a lignin-carbohydrate complex is reported. Biscuits containing non-caloric sweetener soluble (2.5%) and insoluble (5.6%) dietary fiber, natural antioxidants (1.34 mg of gallic acid equivalents/g) and α-glucosidase inhibitors (1 g of biscuit–1 mg of acarbose) achieved a high sensorial score (7.2 out of 9) when almond shell was incorporated to them. The application of a fraction from almond shell containing lignin-polysaccharides complexes as food ingredient in biscuit formulations for people with particular nutritional requirements is feasible and new.