Extração, propriedades físico-químicas e utilização de mucilagem de chia (Salvia hispanica L.) como substituto de gordura em biscoitos

Abstract

Chia seeds (Salvia hispanica L.) present in their composition amounts regarded as gluten-free proteins, essential fatty acids, minerals, vitamins, phenolic acids and dietary fiber, standing out mucilage released when those seeds are soaked into water. That mucilage acts like soluble fiber and displays properties of hydration, water-holding, viscosity development and freshness conservation, especially in oven products; nevertheless, it remains tightly stuck to the seed which makes its extraction difficult. In this context, this study intended the extraction of the chia mucilage by three different methods: pressing and freeze-drying (A method), drying and friction (B method) and drying, rehydration and freeze-drying (C method) with variations at the extraction temperature (25°C, 45°C, 65°C and 85°C), evaluating the yield. In the chia mucilage by the highest yield extraction method analyses of chemical composition, solubility, water absorption capacity (CAA), water-holding capacity (CRA), oil-holding capacity CRO), emulsifying capacity (AE), color, scanning electron microscopy and rheological behavior. With the obtained mucilage by the highest yield extraction method, biscuits with a reduction of 10%, 20% and 30% of the formulation fat were obtained. In the biscuits, the chemical composition, color, texture and sensorial analyses were carried out. The method which presented the highest yield was the C method at the temperature of 85°C, its being of 6.44%. The chia mucilage presented high values of solubility, CRA and AE, but low values of CAA and CRO. Relative to color, the mucilage obtained displayed beige coloration and on the images of the mucilage, on the structure, a brittle and non-uniform aspect was found. As regards the rheological behavior, the mucilage dispersions presented behavior closer to the Newtonian one at the concentrations of 0.2% and 0.4%, and as a pseudoplastic fluid at the concentrations of 0.6%, 0.8% and 1.0%. The biscuits with a replacement of fat by chia mucilage presented reduction in the lipid contents, in the energy values, in luminosity (L*) and in the yellow color (b*). The increase of the replacement of fat gave greater hardness in the biscuits with replacement of 20% and 30%. In the analysis of sensorial acceptance of the biscuits, it was found that the acceptance scores for the treatments with replacement of 20% and 30% of fat were maintained, with variation of the scores of “I liked it slightly” to “I liked it moderately” and for purchase intention, scores between “I do not know” to “I would probably buy it”, respectively. Chia mucilage proved to a promising alternative to be utilized as a replacer of fat in the biscuit-making process.