Extrusion Cooking of Maize/Spirulina Mixture: Factors Affecting Expanded Product Characteristics and Sensory Quality

Abstract

The physical properties and sensory attributes of an extruded product are generally influenced by a large number of process and ingredient variables. Expansion is the most important physical property of the snack food. The effects of spirulina powder (SP) addition to maize flour (MF) on the physico‐chemical and sensory quality of extrudates were investigated. Addition of SP (7.5%) in the MF blend increased the carotenoids, protein and zinc contents and produced crisp to hard‐textured extruded products. The protein, zinc and carotenoid content of extruded product were respectively, 14.63%, 6.66 mg/Kg and 138.83 mg/kg. Optimum operating conditions for development of SP and MF blended extrudate were: barrel temperature (109.2C), screw speed (280 rpm) and feed moisture (16% d.b.). These optimum process conditions resulted lateral expansion of 161.46%, bulk density, 0.18 g/cm3; water absorption index, 6.22 g/g; and overall acceptability, 6.12 with desirability 0.809. Practical Applications Extruded food products produced from cereals are usually low in protein and have a poor biological value due to their limited essential amino acid contents and are often fortified with proteins. Spirulina – cyanobacteria has been used by different populations as protein source and other nutritional requirement. Successful incorporation of spirulina into cereal‐based extruded products could deliver physiologically active components, represents a major opportunity for food processors who are engaged in providing the consumer a healthy maize‐based product, which is currently lacking in the market place.

Effect of Spirulina addition on the physicochemical and structural properties of extruded snacks

“…This effect is due to the fact that higher moisture content decreases the shear of the plasticized mass inside the extruder, reducing the gelatinized starch and prevent the growth of air bubbles of the snacks (Stojceska et al, 2009;Sumargo et al, 2016). The hardness of the snacks ranged from 14.1 to 32.8 N. Similar results (16.2 to 43.4 N) were reported by Joshi et al (2014) on corn extrudates added with microalga.…”

“…WAI is related to the absorption and retention of water by the constituents of the raw material, and can be used as a gelatinization index (Joshi et al, 2014). The increase in feed moisture positively influenced the WAI (p <0.01), due to the increase in content of water available.…”

“…Some studies using Spirulina on extrudates composition verified nutritional increase (Morsy et al, 2014;Joshi et al, 2014). Therefore, this study aimed to evaluate the effects of Spirulina sp.…”

Process optimization of extrusion variables and its effect on properties of extruded cocoyam (Xanthosoma sagittifolium) noodles

“…This could also be related to the generally low values for bulk density and ER, resulting in a more porous and puffed noodles with better color. These parameters have earlier been observed to impart changes in the lightness of the extrudates (Chaiyakul, Jangchud, Jangchud, Wuttijumnong, & Winger, 2008; Joshi, Bera, & Panesar, 2014). Observations drawn from the coefficient of regression model (Table 4), indicated that the positive quadratic effect of SS ($X_2^2$ ) and negative quadratic interactive effects of FMC and BT ( X 1 X 3 ) significantly ( p  < 0.05) influenced the L * and b * of the cocoyam noodles.…”

“…The textural values of the cocoyam noodles ranged from 11.93 to 16.17 N. These values were observed to significantly ( p  ˂ 0.05) differ, as a function of FMC, SS and BT (Table 5). More significantly, higher temperature extrusion usually results into a product with more air cells, lighter (reduced wall thickness), and softer extrudates (Joshi et al., 2014). Coefficient of the regression models of the texture with respect to their linear, quadratic, or interaction effects did not show significant ( p  < 0.05) effect, but the influences of these process variables observed are shown on the surface plots (Figure 1l).…”