Implication of enzymatic and chemical treatment on high ammoniated natural rubber latex

Abstract

Enzymatic treatment is commonly applied in natural rubber latex (NRL) to produce deproteinized natural rubber (DPNR). The enzyme plays an essential role in degrading the protein molecules into smaller fragments thus easily removed during processing. The DPNR is an alternative raw material of rubber with minimal amount of protein and other non-rubber components which enhances the value of rubber in certain specialized products. Application of DPNR for latex dipped products was initiated as an option to tackle the allergenic issue of NRL glove. However, these ‘low protein latex’ or DPNR-Latex (DPNR-L) have been reported to give uncertain and at times poorer mechanical property and stability. The destabilization of NRL occurs from a build-up of volatile fatty acids (VFA) resulted from microbial metabolic activities. Hence, ammonia is used to stabilize the NRL. In this study, the fundamental approach of making DPNR-L from high ammoniated NRL (HA-NRL) via enzymatic (alcalase and pepsin) and chemical (urea) treatment was conducted. Effect of alcalase, pepsin and urea on the protein content and allergenicity in HA-NRL were studied and discussed. The mechanical property and stability were also evaluated to determine the suitability of the treated HA-NRL use for latex dipped product. Efficiency of alcalase in deactivation of allergenicity was rather good. However alteration in the protein biological structure is detrimental to the latex mechanical property. Meanwhile, the presence of pepsin in HA-NRL caused protein aggregations. As a consequent, insignificant increment of allergenic proteins was detected. Interestingly, the mechanical strength of HA-NRL treated with pepsin was 20% higher than the untreated latex. Treatment with urea shows approximately similar effect as pepsin. Unfortunately, none of these materials could stand alone as protein denaturing agent and mechanical property booster. However, these results proved that the presence of proteins is crucial to NRL mechanical property and that the enzymes and urea could be used to treat HA-NRL based on the purpose of the product application.