Effect of dough ingredients on apparent viscosity and properties of extrudates in twin‐screw extrusion‐cooking

Abstract

A capillary-type viscometer was used in a twin-screw extruder to measure the apparent viscosity of cooked-extruded wheat-flour dough with various ingredients: lecithin, palm oil, sucrose, whey, sodium chloride, and bran. The effects of concentration of these ingredients on dough rheology and physical properties of extrudates (apparent density, expansion ratios, mechanical, and crispness properties) were measured. The role of ingredients was discussed in terms of their physico-chemical effect on biopolymer conversion. The correlations between apparent viscosity of dough and physical properties of extrudates were developed.

Effect of Extrusion Conditions on Cassava/Soybean Extrudates

“…Ralet et al [44] reported that wheat bran increased its water uptake after extrusion. This could be as a result of the disruption of covalent or non-covalent bonds in the carbohydrate and protein moieties, leading to smaller, more soluble molecular fragments [45,46]. These observations confirm similar findings reported for starch-based extrudates obtained either using single or twin screw extrusion [47,48].…”

Expansion mechanism of extruded foams supplemented with wheat bran

“…Only few studies investigated the effect of wheat bran on the shear viscosity of extruded starchy melts. Moore et al (1990) and Wang et al (1993), using a capillary rheometer, reported no change in the apparent viscosity of cooked dough supplemented with up to 16% of wheat bran. However, the composition of the bran was not specified and the effect of bran on the flow behavior was not characterized.…”

“…However, its valorization in extruded food products is constrained due to its negative effect on product expansion and organoleptic properties (e.g. Wang et al, 1993;Brennan et al, 2008). Several works reported a decreasing effect of wheat bran on the expansion properties of starchy foams (Breen et al, 1977;Hsieh et al, 1989;Moore et al, 1990;Wang et al, 1993;Yanniotis et al, 2007;Brennan et al, 2008).…”

Online Shear Viscosity Measurement of Starchy Melts Enriched in Wheat Bran

“…Supplementation of extruded products with wheat bran is a cost‐efficient way of increasing their dietary fiber content. However, wheat bran/fibers addition was reported to decrease expansion and increase the bulk density of extruded food foams (Breen and others 1977; Hsieh and others 1989; Moore and others 1990; Wang and others 1993; Yanniotis and others 2007; Brennan and others 2008). The reduced diameter, increased bulk density, and/or change in cellular structure characteristics resulting from the addition of wheat bran lead to harder textures (Wang and others 1993; Yanniotis and others 2007; Brennan and others 2008), less preferred by consumers.…”

“…Only few works investigated the effect of bran on the melt rheological properties (Moore and others 1990; Wang and others 1993). In relevant studies, the shear viscosity was assessed using an online slit viscometer.…”