Influence of extrusion conditions on the physical and nutritional properties of snacks from maize and pearl millet

Abstract

The partial replacement of maize grits with pearl millet grains in snacks can increase their nutritional quality. This study aimed to design healthier and less expensive extruded snacks and study extrusion conditions (moisture and temperature) according to an experimental central rotational composite design. The improved snack, optimized as the desirability index of the highest expansion capacity, was extruded and flavored with cheese or ham. Acceptability was analyzed in terms of appearance, texture, flavor, and overall value attributes by typical consumers of snacks. Moisture, as opposed to temperature, was significant factor for the snack expansion. The improved snack was classified as a rich source of dietary fiber (5.9 g·100 g−1 of fresh food) and protein (10 g·100 g−1). The snacks were accepted with most scores above 6 (liked it a little). By replacing 50% of maize grits with pearl millet grain, more sensorial acceptable and healthier snacks can be obtained.

Practical applications We observed that under minimal moisture and mild temperature conditions in the third zone of the extruder, snacks rich in fiber and protein, with the best expansion index and a specific volume similar to that of commercial snacks prepared with only maize grits (of poor nutritional quality) are produced. The optimized processing parameters established by mathematical modeling to reach a good expansion index could be applied to other pieces of extruder equipment for industrial purposes, as the results did not undergo any great variation at distinct moments of extrusion. We demonstrated the potential for commercialization of snacks made from maize grits and whole grain pearl millet as a product with added nutritional value. Our interest is to offer healthier options for convenience foods as high-fiber snack foods with low cost, high nutritional quality, and good acceptance by consumers, mainly children, who make snack products one of the most consumed convenience foods in the word.