Desenvolvimento de extrato hidrossolúvel de painço em pó (Panicum miliaceum L.)

Abstract

Millet has been introduced in human food due its high nutritional value and facility to be used in the food industry. Furthermore, miller is considered a non-allergenic ingredient and without gluten. Thus, the objective of this study was to develop a millet water-soluble extract as food ingredient, adding the nutritional properties of the grain and apply in gluten-free cake formulations. The powder millet water-soluble extract (PMWE) was obtained by aqueous extraction followed by spray drying. The proximate composition, chemical and physicochemical properties of PMWE were evaluated. To evaluate the effect of PMWE application, three gluten-free chocolate cake formulations were obtained (F1=100% rice flour; F2=50%/50% rice flour and PMWE; F3=100% PMWE) and characterized as to the proximate composition and physicochemical properties. PMWE exhibited moisture content within the recommended limit for spray dried powder products (< 4%) and presented significant amounts of proteins (13.38%), carbohydrates (75.98%) and lipids (7.51%). The carbohydrate content of the PMWE was 75.98%, related to the presence of starch in the grain and dietary fiber in the grain. As for mineral composition, higher amounts of calcium, copper, potassium, magnesium, manganese and phosphorus were observed for PMWE when compared to wheat and rice flours reported in the literature, demonstrating its nutritional importance as an alternative ingredient. The pH (5.75) and acidity (0.79 g acid 100 g- 1) values were within the expected range when compared to flours in general. The PWME was considered a hygroscopic sample. The instrumental color measurement showed a lightness powder (L* = 56.48), greenness (a* = -1.76) and yellowness (b* = 11.82) color. The total phenolic content of 106.95 mg gallic acid 100 g-1 and the DPPH value of 107.33 mg Trolox 100 g-1 confirm the antioxidant activity of PMWE. The infrared analysis (FTIR-ATR) allowed to observe characteristic bands of the functional groups of the sample, being confirmed the presence of carbohydrates, proteins and lipids. Thermal analysis confirmed the presence of starch in the sample, with the identification of a thermal event characteristic of starch gelatinization at 77 °C, in addition to protein denaturation at 210 °C and thermal degradation of PMWE at 304 °C. The gluten-free cake formulations made with PMWE had lower moisture content and higher protein and ash content, suggesting an improvement in the nutritional characteristics of the product with the replacement of rice flour by PMWE. Aw values did not differ between cake formulations. The cakes with PMWE had a softer texture, revealed by the texture profile, and a lightness color and a redness and yellowness mass color. The results obtained allowed concluding that the PMWE presented values of proximate composition and antioxidant activity similar to millet grains reported in the literature, suggesting that the production process made it possible to maintain the nutritional characteristics of the product. PMWE presents as a viable alternative for application in gluten-free confectionery products such as cakes.