蛋白质和磷脂对天然胶乳成膜性能的影响

Effect of Proteins and Phospholipids on Film Formation Properties of Natural Rubber Latex

成膜性是天然胶乳的重要工艺性能,直接影响制品的质量。天然胶乳中蛋白质和磷脂的含量对其成膜性能有重要影响。文中采用高速冷冻离心、碱性蛋白酶及脂肪酶处理浓缩天然胶乳(CNRL)制备脱蛋白胶乳(DPNR)、脱脂肪胶乳(PNR)、脱蛋白脱脂肪胶乳(P-DPNR),研究蛋白质和磷脂对天然胶乳粒径、相对分子质量、干燥性能及胶膜表面形貌的影响,并分析其成膜机理。结果表明,经过离心及酶处理后,蛋白质、磷脂含量降低,平均粒径变大;DPNR和PNR的重均相对分子质量分别降低1.33×10^5、1.34×10^5,相对分子质量分布变宽;胶膜干燥速率提高;胶膜表面形貌趋于平坦,粗糙度R_a值降低。分析蛋白质和磷脂对胶乳成膜过程的影响,提出成膜过程机制图,成膜过程可分为水分蒸发、颗粒变形、聚集、相互扩散4个阶段。

Film formation property of natural rubber latex is an important process property of latex,which directly affects the quality of products.Film formation properties of latex are known to be influenced by the content of proteins and phospholipids.In this paper,the deproteinized natural rubber(DPNR),lipid-free natural rubber(PNR)and lipid-free DPNR(P-DPNR)were prepared by high speed refrigerated centrifugation,treated with enzyme decomposition(alkaline proteinase,lipid enzyme)and high speed centrifugation,research on the impact of proteins and phospholipids to the particle size,molecular weight,drying properties,and surface morphology was applied,and the film formation mechanism was analyzed.The results show that nitrogen content and lipid content decreases;the average particle size becomes larger;the average molecular weight of DPNR and PNR decreases by 1.33×10^5,1.34×10^5,the molecular weight distribution becomes wider;the drying rate of film increases;the surface morphology of the film tends to be flat,the roughness of film decreases.The influence of protein and phospholipid on the film formation process of latex was analyzed,and the mechanism of film formation process was proposed.The film formation process can be divided into four stages:water evaporation,particle deforming,coalescence,and inter-diffusion.