Modelling and optimization of the extrusion process in a snack of barley/corn and nutritional evaluation of the optimized product

Abstract

Background and objectives Most of the snacks in the market contain a single cereal and show nutritional deficiencies. The aim of the study was to optimize the conditions of the extrusion process for a snack with barley/corn mix and their physicochemical evaluation, amino acid content, protein digestibility, and resistant starch as a healthy snack. Findings The regression model indicated that the variables water absorption index, water solubility index, and hardness can be explained by the models. Expansion index showed no significant effect. The optimal conditions of the process of extrusion were feed moisture 38%, die temperature 130°C, and barley/corn mix 50:50. An unflavored snack with 392.11 kcal/100 g was obtained, considering it is flavored, its estimated energy contribution is around of 446.11 kcal/100 g. The concentration of essential amino acids in the extrudate meets the requirements established by FAO/WHO/UNU for children and adolescents. Protein digestibility increased and the content of available and resistant starch was reduced. Conclusions The optimal conditions of extrusion allowed to obtain an alternative snack with the essential amino acid requirements and higher protein digestibility. Significance and novelty The combination of two cereals allows to supplement the requirement of essential amino acids and greater protein digestibility.

Impact of extrusion processing on the nutritional and physicochemical properties of intermediate wheatgrass (Thinopyrum intermedium)

“…A significant ( p < .05) reduction of up to 9.64% in total dietary fiber (TDF) was observed after extrusion. A similar observation was reported for extruded snacks made from barley and corn mix (Román‐Gutiérrez et al, 2021) and snacks made from rice, pea, and carob flour blends (Arribas et al, 2017), although the levels of reduction (~27% and 28%–34%, respectively) were higher in those studies. This could be due to the initial fiber content of the raw materials, which was higher in our study.…”

“…The fat content of IWG flour was slightly higher than those reported for different IWG varieties in a previous study (1.84–4.02 g/100 g) (Tyl & Ismail, 2019), possibly due to varietal differences and growing location, which can influence grain composition (Mpofu et al, 2006). Extrusion resulted in a significant ( p < .05) reduction in fat content of IWG, possibly due to the expulsion of lipids from the food matrix as a result of the high pressure and shear effect (Román‐Gutiérrez et al, 2021). There was no significant difference in fat content between the extrudates, indicating that screw speed did not significantly affect the lipid content of the extrudates.…”

“…However, slight decreases were observed in alanine, threonine, glycine, valine, proline, isoleucine, leucine, methionine, phenylalanine, glutamic acid, and aspartic acid after extrusion. This could be due to the occurrence of Maillard reaction during the extrusion process (Román-Gutiérrez et al, 2021). Lysine has been shown to give the most intense Maillard browning (Ajandouz & Puigserver, 1999).…”

Physical and microstructural quality of extruded snacks made from blends of barley and green lentil flours

“…Most puffed snacks in the market are made from a (refined) single cereal source and therefore, nutritionally inferior from the perspective of lower protein content and incomplete amino acid profile (e.g., limiting in the amino acid lysine) (Asif et al, 2013; Román‐Gutiérrez et al, 2021). Furthermore, most studies on nutritionally enhanced puffed snacks up to date have focused on enriching either the protein (Lazou et al, 2011; Matthey & Hanna, 1997; Patil et al, 2016) or the dietary fiber (Kumari et al, 2018; Sharma & Gujral, 2013) content, not both.…”

Optimizing the extrusion conditions for the production of expanded intermediate wheatgrass (Thinopyrum intermedium) products

“…Compared to a full factorial design, the RSM's experimental design reduces the number of experiments required to evaluate independent variables and their interactions (Kalitsis et al., 2021). RSM has been extensively used for process optimization in the production of extruded cereal grains (Charunuch et al., 2014; Román‐Gutiérrez et al., 2021; Singha, Singh, et al., 2018).…”