Optimal conditions for deproteinizing natural rubber using immobilized alkaline protease

Abstract

BACKGROUND: Natural rubber latex contains allergenic proteins. Therefore, processes for deproteinizing the latex are needed. An immobilized enzyme process for deproteinization is reported. An optimal protocol was first developed for immobilizing a protease on cellulose−chitosan composite beads. The beads were then used in developing an optimal deproteinization treatment. The main effects and the interactions of the factors for the two processes were identified using a two-level full factorial experimental design.RESULTS: Under optimal conditions (15% cellulose in beads, immobilizing reaction pH of 9, immobilization period of 24 h), the beads attained the highest specific activity of 1685.3 U g −1 beads. Using these beads, the optimal conditions for deproteinization of the latex were: an enzyme loading of 0.1 parts per hundred of rubber (phr), a sodium dodecyl sulfate concentration of 20 phr, 30 • C, and a treatment period of 12 h. The nitrogen content of the rubber was reduced to 0.012% from an initial value of 0.3%. The enzyme beads were operationally stable and could be reused for at least five cycles. CONCLUSIONS:The optimized treatment effectively deproteinized the natural rubber. The final product was free of peptides. This deproteinization treatment was more effective than the conventional urea-based treatment performed for comparison.

Zeta Potential and Environmental Scanning Electron Microscopy Analysis in Deproteinisation of Natural Rubber Latex

“…However, as mentioned earlier, it is uncertain whether the particles are permanently attached together or just in contact with adjacent particle. Treatments with urea will not break the proteins but serves as denaturants which facilitates the removal of proteins from NRL through centrifugation and washing process [23]. When only SDS was used during deproteinisation process, the particle seemed to have an orderly arrangement with a distinct particle shapes and without the particles merging effect (Figure 4b).…”

Environmental impacts of examination gloves made of natural rubber and nitrile rubber, identified by life‐cycle assessment

“…This preference for nitrile gloves is driven by the presence of potentially allergenic proteins on the surface of NR gloves. [5,6] These proteins occur naturally in the latex harvested from the rubber tree and can be removed with additional processing. [5,6] Allergenicity notwithstanding, NR gloves have superior barrier property, elasticity, resistance to sharp objects, and strength than nitrile gloves [4,7] and are preferred in many applications.…”

Deproteinized natural rubber film reinforced with silane-modified silica nanoparticles

“…Unfortunately, a long incubation time and strict temperature control is necessary for enzymatic deproteinization. [13][14][15][16][17][18][19] Urea is used as a protein denaturant in the presence of a surfactant. [20][21][22][23] Washing NR latex with non-ionic surfactants such as sodium dodecyl sulphate (SDS) 24 and polyethylene glycol 25 efficiently reduce proteins from the rubber particles by transferring them to the serum phase.…”