Evaluating Biodegradable Plastics with in vitro Enzyme Assays: Additives Which Accelerate the Rate of Biodegradation
This chapter contributes to the understanding of the initial mechanism of deterioration, specifically the role of microbial enzymes in the hydrolysis of biodegradable additives, and to makes possible more efficient and standardized methods for determining "biodegradability". It has been found that the rate and extent of the enzymatic degradation of biodegradable plastics can be significantly improved with the use of additives such as surfactants in the enzyme mixture. In the standard assay method the biodegradation of starch in plastic films was based on the measurement of glucose produced as the starch was hydrolyzed by a mixture of amylases. The treatment of the polymer by boiling also resulted in an improvement of the degradation of the starch; however, increasing degradation by this physical disruption of the material was not further examined. A plastic sample containing 40" starch or cellulose in high density polyethylene (HDPE) was pretreated with Igepal or SDS for seven days at 60ºC.