Emulsion gel enriched with a barley β-glucan concentrate for reducing saturated fat in biscuits

Abstract

Solid fats (e.g., margarine) provide appealing taste, flavor and texture to bakery products including biscuits. However, margarine is rich in saturated and trans fatty acids, which are associated with increased cardiovascular disease risk. An oil-in-water emulsion gel was formulated with barley flour β-glucan concentrate/olive oil/water (13/10/77 w/w/w) to replace margarine in biscuits at 50–100% substitution; a full-fat biscuit (30% margarine) was also tested (control). A multi-instrumental analytical approach was employed to explore the dough rheological behavior and biscuits quality characteristics. Elasticity and viscosity of control dough were greater than those of the formulated composite doughs with the emulsion gel preparations as showed by frequency sweep and creep-recovery testing, while the flexural modulus and fracture strength of the biscuits decreased with increasing level of margarine substitution. Biscuits without margarine exhibited smaller diameter and higher thickness, compared to control, whereas products with higher fat substitution level had higher moisture and water activity. Nevertheless, the 50% fat substituted biscuit had similar flexural properties and microstructure, as revealed by texture analysis and SEM microscopy, respectively, to those of control; additionally, this reduced-fat product received acceptable ratings for flavor, fragility, hardness and overall acceptability by sensory analysis, similar to control. Furthermore, the product with higher margarine substitution levels exhibited slower rates of in vitro lipid hydrolysis (on biscuit weight basis) upon enzymatic intestinal digestion. Overall, the use of barley flour emulsion gel as substitute of solid fats in biscuits offers the advantage of producing healthier and acceptable products depending on the degree of fat replacement.