Microbial Desizing Using Starch as Model Compound: Enzyme Properties and Desizing Efficiency

Abstract

A film of sizing agents protects yarn during weaving. Its removal in a subsequent washing process causes 50% of the organic effluent load of textile finishing processes and requires large amounts of auxiliary chemicals (e.g., surfactants). Microbial desizing is a new bioprocess that uses the acidifying culture of a two-phase anaerobic digestion plant for the removal and partial degradation (acidification) of the sizing agent. Soluble starch is used in this study to characterize the enzymatic properties in the supernatant of the desizing culture and to link them to desizing efficiencies. The supernatant of the culture (grown at 37 degrees C, pH 5.5) displayed the highest enzymatic activity between pH 4 and 5 and in a broad temperature range (20-80 degrees C). Highest metabolization rates were determined with the substrate amylose. Short chain dextrins (average of 5 and 10 glucose units) and amylopectin were converted significantly more slowly. At 37 degrees C the half-life time of the enzymatic activity in the supernatant was 45 h. In a desizing test a decisive reduction of the chain length was found already after 1 h (allowing starch solubilization). A microbial desizing experiment with dyed, native maize starch demonstrated the efficiency of the proposed bioprocess.

Application of enzymes for textile fibres processing

“…For fabrics made from cotton or blends, the warp threads are coated with an adhesive substance know as 'size' to lubricate and protect the yarn from abrasion preventing the threads to break during weaving. Although many different compounds have been used to size fabrics, starch and its derivatives are the most common because of their excellent film forming capacity, availability and relatively low cost (Feitkenhauer et al 2003). After weaving, the sizing agent and natural non-cellulosic materials present in the cotton must be removed in order to prepare the fabric for dyeing and finishing.…”

Effect of Desizing Treatment on the Bagging Behavior of Denim Fabrics

“…The most common sizing agents are starch, polyvinyl alcohol (PVA), carboxy-methyl-cellulose (CMC), and acrylates, 3 but starch and starch combined with polyvinyl alcohol are most applied to size denim fabrics. [4][5][6][7] Despite this, untreated denim garments remain extremely rigid. In addition, this step of pretreatment of the fabric affects the wettability of the fabric and the fabric handling.…”

Conventional and Single-step Pretreatment Process of Cotton Woven Fabric

“…Desizing is a typical process in pretreatment by which size materials are removed from cotton woven fabrics, cotton blends and all grey synthetic materials which contain sizes. Sizing agents on the warp yarns which applied for better weaving efficiency in the weaving mills, have to be removed before further processing in textile [3][4][5][6][7][8]. Since natural impurities such as cotton wax, pectin substances and protein are associated mainly within the primary wall, the scouring process aims to remove this wall.…”