Functional Properties of Chia Seed Mucilage Supplemented In Low Fat Yoghurt
Amira M.G. Darwish , Randa E. Khalifa, Sobhy A. El Sohaimy
Modern diet lifestyle demands of healthy natural foods represent a challenge for food manufacturers to lead towards the healthy new trends. This work aimed to study the microstructure of chia seed (Salvia hispanica L.) and its mucilage, provide chemical and functional properties of mucilage before supplementation in low-fat yoghurts and evaluate its impact on products’ composition, texture, and acceptance. The micro morphology of chia seed and its mucilage were described via scanning electron microscope (SEM). For physical functional properties evaluation; functional groups were studied using Fourier Transform Infrared (FTIR) spectroscopy; the thermal behavior was analyzed using Thermogravimetric Analyzer (TGA), and Water/ Oil Holding capacities (WHC/ OHC) were assessed. The gross chemical composition of mucilage was studied before supplementation with various concentrations (1, 1.5 and 2%) at different ratios of fat content (1, 2 and 3%) yoghurts, monitoring mucilage effect on chemical, rheological (using Texture Analyzer) and organoleptic properties of yoghurts. Chia mucilage micrographs showed fine fibrous network structure supported by high fiber, protein, ash and fat values (12.4, 10.68, 9.64, and 3.10% respectively). The FTIR analysis indicated the presence of uronic acids, mannose, carboxylic acid, pyranose, glucopyranose, xylopyranose groups in mucilage polysaccharides, which influenced its thermal stability. Mucilage showed comparable high WHC/OHC values (5.25g water, 5.85 g oil/ g sample) that nominate it to perform as a stabilizer and emulsifier. Along with increased chia mucilage concentrations in fortified yoghurt, fiber content elevation subsequently reflected on higher values of springiness, and descendant hardness values that produced “soft” yoghurts as described in sensory evaluation.
Key words: FTIR; Microstructure; SEM; Texture analysis; TGA.