Effect of ethanol addition on physical properties of extruded starch

Abstract

The aim of this study was to determine selected properties of extrudates produced from potato starch with the addition of ethyl alcohol. Ethyl alcohol at 5, 10, 15, and 20% concentration was added to potato starch with moisture content of 18 and 23%; the starch was then extruded in single-screw extruder. The extrusion process was carried out in three temperature variants. The resultant extrudates were determined for color, expansion ratio, and mechanical properties. Properties of the extrudates were found to depend on parameters of the extrusion process, moisture content of the extruded sample and ethanol content. Morphological characteristics of the extrudates produced were affected by temperature of the extrusion process, i.e., increasing extrusion temperature resulted in a higher expansion ratio, a lower density, and higher saturation of white color. The extrudates produced from starch with the addition of ethanol were whiter, than those prepared without ethanol. The samples produced with ethanol addition were characterized by a higher number of air spaces and thinner walls, when compared to the those prepared from starch moistened only with water. All mechanical properties were lower in the samples prepared with the addition of ethanol, as compared to the extrudates without its addition.

Effect of ethanol on properties of extrudates enriched with high‐fibre by‐products

“…walls of bubbles break and volatile substances contained in them are released. This process was observed in the mixtures with 4% ethanol (Zhou & Hanna, ; Tomaszewska‐Ciosk et al ., ). All studied factors had a significant effect on values of the analysed mechanical properties (Table ).…”

“…Ethanol content in extruded mixtures had no statistically significant effect on other colour parameters either. A distinct effect of ethanol presence was also observed in the case of lightness of the extrudates made of potato starch with different additions of water and ethanol (Tomaszewska‐Ciosk et al ., ).…”

“…Similar results were reported by Miladinov and Hanna () in their study on acetylated corn starch containing 70% of amylose, and by Tomaszewska‐Ciosk et al . () in their research with potato starch extruded in various temperature variants. It is likely that through manipulating ethyl alcohol addition to the extrusion mixture it would be possible to manufacture a product with hardness and texture acceptable by consumers even at lowered extrusion temperature, which would minimise losses of components sensitive to high temperatures (e.g.…”

“…Mechanical properties of extrudates were measured according to the method described by Tomaszewska‐Ciosk et al ., , using an Instron 5544 Tensile Tester with a Bend Fixture attachment, at crosshead with the cutting blade speed of 4.5 mm min −1 and its loading of 2 kN. The distance between fulcrums of the extrudates was fixed at 40 mm.…”

“…Their values can be modified only to a little extent, because temperature increase (besides increasing expansion ratio) inactivates thermolabile components of the extruded mixture and reduces the nutritive value of the finished product, whereas water content increase in the extruded mixture above the limit value does not increase the expansion ratio but even decreases it (Mendonc ßa et al, 2000). The possibility of controlling expansion rate of the extrudates made of corn and potato starch through ethyl ethanol addition to the extruded mixture was demonstrated in few studies (Miladinov & Hanna, 2001;Tomaszewska-Ciosk et al, 2013). Because starch is the major texture-forming component of food extrudates, changes occurring in the extruded cereal products may be predicted with high probability.…”