Extrusion cooking and bioconversions

Rheological Properties of Rice Starch at High Moisture Contents during Twin-screw Extrusion

“…There is another theoretical assumption that could be checked from these data. Wall shear stress and wall shear rate calculations were based on the principles of slit rheometry, and by considering the RabinowitschMooney correction for power fluids (shown in Eqns [2] to [6]). Viscosity is simply the ratio of shear stress to shear rate.…”

“…High moisture content (up to 700 g/kg) in the feed stream resulted in increased starch hydrolysis. Continuous extrusion cooking also presents an attractive alternative method to pretreat starchy materials for subsequent ethanol fermentation (5). High moisture extrusion has been utilized by a hazelnut candy factory in Ordu, Turkey to knead and mix crushed hazelnut, cocoa powder, and other ingredients to a thick paste which is shaped at the die to form a desired product.…”

Dynamic Response of a Twin-screw Lab-size Extruder to Changes in Operating Variables

“…The literature on food extrusion does not include any dynamic studies at high moisture contents ( > 450 g/kg). However, wet extrusion has been used by researchers (1,2) and has future potential applications such as texturization and processing of various foods and feeds. A stable extrusion process is necessary to establish a consistent product quality.…”

“…Another potential area of interest for high moisture dough is the use of extruders as bioreactors, where the combination of high moisture and extruder operating conditions is used to promote the enzymatic conversion of starch. The extrusionliquefied starch may be used for subsequent syrup manufacture, ethanol, or other fermentations (2). During extrusion starch molecules undergo a variety of reactions such as gelatinization and molecular degradation due to the thermal and mechanical treatment.…”

Effect of screw profile on extrusion‐cooking of wheat flour by a twin‐screw extruder

“…Many products, such as flakes, pasta with special sizes and shapes, are all made in minutes by a modern extrusion equipment rather than in hours by a conventional method. Linko et al (1983) have also demonstrated that an extruder could be used as a bioreactor for liquifying starch through enzymatic reactions and have pointed out the importance of residence time distribution (RTD) as a useful measure for scale-up and determination of optimum process conditions (Bruin et al, 1978). It is influenced by operating conditions, e.g.…”