Relationships between processing conditions and starch and protein modifications during extrusion‐cooking of pea flour

Abstract

Pea flour was extruded under various conditions; extrusion treatment was characterised by specific mechanical energy (SME), moisture content, shear rate at the die and product temperature. Product transformation was measured by starch solubility, protein solubility in specific buffers and by immunoassay with anti-legumin antibodies. Response surfaces showed that SME influenced starch and protein solubility more than did temperature. Decrease of protein solubility was attributed to formation of non-covalent bonds and disulphide bonds which could partly take place at the die, according to flow conditions. The most severe extrusion conditions (SME > 250 kWh t-') led to the creation of other covalent bonds. Immunoassay proved an efficient method for assessing the severity of treatment by following the loss of legumin antigenicity.

Twin-screw extrusion of cassava starch and isolated soybean protein blends

“…Textural modifications of extrusion products through blending of the components were reported for several blends by Nyanzi and Maga [18], Sotillo et al [19] and Valle et al [20]. The results obtained showed the following best explanatory model equation for hardness: The hardness varied from 12.3 to 66.0 N for all treatment combinations (Tab.…”

Proximate composition and digestibility of fermented and extruded uji from maize–finger millet blend

“…We did not measure water-soluble starch in fermented and cooked uji because cooking in excess water causes gelatinization of starch and formation of a colloidal matrix of amylose and amylopectin. Water-soluble starch significantly increased after extrusion as a result of disruption of the granular structure and macromolecular chain splitting (Della Valle et al, 1994) and this corresponded to an increase in in vitro starch digestibility. Extrusion processing can therefore be used to produce digestible starch fraction and has the potential to replace traditional labour intensive and time-consuming methods used in the production of uji.…”

Extrusion of Soybean and Wheat Flour as Affected by Moisture Content

“…This effect was also found for wheat gluten/potato starch blends (Yuriev et al, 1994). Textural modifications of extrusion products through blending of the components were reported for several blends by Nyanzi and Maga (1992), Sotillo et al (1994), and Valle et al(1994). In many cases, the increased expansion ratio correlated with better texture of the products.…”