Characterization of Mucilage from Roasted and Steamed Flaxseed and Its Utilization in Low-Fat Cake

The effect of heat treatment (roasting and steaming) of flaxseed on physicochemical properties of mucilage and its potential to use as fat replacer in cake formulation were investigated. Flaxseeds were roasted at 100, 130, 160 ºC for 5, 10, 15 min, and steamed for 5, 10, 15 min before mucilage extraction. The highest water-holding capacity (22.6%) and oil-holding capacity (4.2%) were observed in mucilage extracted from flaxseed steamed for 15 min, and roasted for 15 min at 160 ºC, respectively. However, heat treatment decreased the foam capacity of the mucilage. The highest emulsion capacity (45.5%) was observed in mucilage from flaxseed roasted at 100 ºC for 15 min. Mucilage was used in cake formulation at 50% replacement with fat. Heat-treated flaxseed mucilage significantly increased the cake’s specific volume, with the highest (2.52 cm3/g) was determined in the cake supplemented by 15 min steamed flaxseed mucilage. Steamed flaxseed mucilage resulted in a softer cake texture. Moreover, mucilage from steamed flaxseed generally resulted in lower color differences in cake samples compared to that from roasted flaxseed. The addition of mucilage increased total dietary fiber content of cake samples and decreased their glycemic index values. Steamed flaxseed mucilage resulted in the lowest glycemic index values. Overall, heat-treatment of flaxseed, especially steam treatment, before mucilage extraction results in mucilage with improved functional properties without resulting any adverse effects at 50% replacement with shortening in low-fat cake quality.