Physicochemical Properties of Flaxseed Fortified Extruded Bean Snack

Key Findings

This project was undertaken to assess the shelf life stability of extruded bean snacks fortified with flaxseed. Bean flours were chosen due to nutritional and functional characteristics of beans in extruded foods. Details are described including the effect of flaxseed on the physicochemical, sensory, and shelf life properties of flaxseed fortified extrudates. Milled flaxseed addition significantly increased water activity and omega-3 fatty acid content of extrudates. The 5 and 10% milled flaxseed addition did not significantly affected lipid oxidation and sensory attributes. Interactions between starch, protein, and lipids may have contributed to the stability of extrudates. Extrudates from bean and corn flour combinations with 5 and 10% flaxseed had good quality and stable shelf life. In addition, consuming 1 oz (28 g) of the 10% fortified extrudate provides a significant level of ALA (33%). These levels of flaxseed are recommended for the creation of gluten-free extruded healthy snacks.

Abstract

Milled flaxseed was incorporated (0–20%) into a combination of bean-corn flours and extruded in a twin screw extruder using corn curl method. Physicochemical parameters such as water activity, color, expansion ratio, bulk density, lipid content, and peroxide values of extruded snack were analyzed. Scanning electron micrographs were taken. Peroxide values and propanal contents were measured over four months of storage. Rancidity scores of extruded snack were measured using a trained panel. As expected, omega-3 fatty acids and bulk density increased with increasing flaxseed fortification levels. Extrudates with more flaxseed had decreased lightness values and expansion ratios. However, only the 15 and 20% flaxseed containing extrudates had expansion ratios that were significantly (? ≤ 0.05) different from the control. In general, no significant difference (? > 0.05) in water activity values was observed in the flaxseed fortified extrudates, except in the navy-corn based extrudates. Peroxide values increased with increased flaxseed levels and over a storage period. However, propanal values did not change significantly in the 5–10% flaxseed fortified extrudates but increased in extrudates with higher levels of flaxseed. Rancidity scores were correlated with peroxide values and did not increase significantly during storage under nitrogen flushed conditions.