Desenvolvimento e caracterização de bolos integrais elaborados com farinha extrudada de milheto (Pennisetum glaucum (L.) R. Br.) adicionados de diferentes tipos de fibras.

Abstract

Consumers are increasingly aware and concerned about their nutrition and health. Thus, the use of alternative cereal sources that have good nutritional composition has become a demand of the industry, especially whole grains. Due to the high fiber content, products with whole grains can change the taste and texture. The application of some treatments, such as thermoplastic extrusion, reduces the content of antinutritional compounds and increases consumer acceptance, in addition to increase the water absorption capacity and the microbiological stability. Cakes are versatile products, as they accept variations in their recipe, allowing them to be enriched with different raw materials. Pearl millet is a gluten-free cereal source of calories, essential micronutrients, vitamins, minerals, phenolic compounds, and present antioxidant properties. It is widely used for human food in African and Asian countries, but in Brazil it is used as mulch and for animal feed. The use of this cereal in easily accessible and accepted foods becomes a strategy for its introduction into human diet in the country. In the first part of this project, the aim was to evaluate the impacts of extrusion on the physicochemical and paste properties of decorticated and whole grain pearl millet flours, by comparing raw (untreated) flours with decorticated and whole grain extruded flours. In the second part, the objective was to develop and characterize whole grain cakes containing extruded whole grain pearl millet flour and different fiber sources (wheat bran, oat bran, rice bran, or psyllium) regarding composition, physicochemical and sensory characteristics. The extrusion process significantly increased (p<0.05) the water absorption capacity of the whole grain flour, but did not change for the decorticated flour (p>0.05). The final and the setback viscosities decreased after extrusion. Breakdown viscosity also decreased in the extruded samples, but the decorticated extruded flour decreased even more, due to the higher exposure of starch to heat treatment when the grain is decorticated. The addition of fibers significantly reduced (p < 0.05) the moisture content of the cakes, which is probably because of the ability of the fibers to bind water, but did not change the specific volume or the external color of the cakes (p > 0.05). All samples were considered as fiber sources. In sensory aspects, the control formulation (without fibers) presented the highest scores for all attributes and for purchase intention. However, all samples showed acceptability with average acceptance scores between "I liked it slightly" and "I liked it a lot" and purchase intention between "I would probably buy it” and "I would certainly buy it". Therefore, the pearl millet flours produced present potential to make different foods, including cakes. Also, the cakes developed may encourage further research in the development of other new products using this cereal.