Extruded snacks based on corn and quinoa flours: development, optimization and characterization

Abstract

Expanded snacks are mostly consumed by children and adolescents. Enrichment with high nutritional value flours would be an interesting option, such that these products, besides supplying energy, could also contribute to the physical and mental development of these individuals. In addition, the nutritional appeal should result in a widening of the target public for the snacks, attracting adults. In the present work, extruded snacks based on corn flour will be developed, enriched by incorporating quinoa flour, aiming at increasing the nutritional value. Corn is widely used in the manufacture of snacks because it expands easily. Quinoa (Chenopodium quinoa) is a pseudo-cereal with an important agronomic potential and high nutritional value, containing an elevated protein level with expressive amounts of the amino acids lysine, methionine and cystine. The raw materials will first be characterized with respect to their physical, chemical, nutritional and microbiological properties. Subsequently, aiming to check which parameters influence the properties of the corn and quinoa flour snacks prepared by the thermoplastic extrusion process,,an experimental design applied to response surface methodology will be carried out , adopting a sequential strategy to determine the optimized conditions. A 2 5-1 fractionated factorial design will first be carried out, the independent variables being: (i) initial moisture content; (ii) amount of quinoa flour; (iii) temperature in the 4th extrusor zone; (iv) temperature in the 5th extrusor zone and (v) screw speed. The dependent variables evaluated (responses) will be: (i) expansion rate; (ii) specific volume; (iii) texture and (iv) nutritional availability of the lysine. As part of the sequential strategy adopted for the experimental design, the next trial could be another fractionated factorial one, but with a reduced number of independent variables and with alterations in the ranges studied as a function of the impact they had on the responses. At the end of this strategy, a Central Compound Rotational Design (CCRD) will be carried out to elaborate the predictive model and define the optimized process conditions. After determining the best extrusion conditions and proportions of the ingredients in the formulation, a final processing will be carried out. The snacks obtained in this last processing will be characterized with respect to their physical, chemical and nutritional properties, and their properties compared with those of a standard corn snack, After the addition of aromas, they will also be subjected to a sensory evaluation for acceptance and purchase intention. (AU)