低温低功率等离子体处理对复合蛋白基薄膜结构性能的影响

Effects of low-temperature and low-power plasma treatment on the structure and properties of composite protein-based films

采用30 W的低温等离子体对乳清分离蛋白-酪蛋白酸钠-甘油复合蛋白膜表面分别进行0、5、10、15、20 min的扫描处理,研究了不同能率的等离子体处理对薄膜中蛋白质二级结构、薄膜微观形态、表面水-油亲和力、机械性能、阻隔性能、热稳定性及灭菌能力的影响作用。结果显示,在结构方面,5~10 min的等离子体处理导致蛋白质二级结构中α-螺旋和β-折叠的程度提高15%左右,薄膜表面更加致密,变得粗糙少孔,玻璃态转变温度(glass transition temperature,T_(g))升至150.60℃,分解温度(decomposition temperature,T_(d))升至197.08℃;在包装性能方面,抗拉强度提高24.10%,断裂伸长率降低27.13%,同时,薄膜的阻隔性提高,其氧气透过率降低至1.20 cm^(3)/(m^(2)·d),水蒸气透过系数降低至5.555×10^(-12) g·cm/(cm^(2)·s·Pa),表面疏水性、疏油性因其表观变化而显著降低(P<0.05),透光率降低20%,水溶性也有轻微下降;在薄膜减菌化处理应用中显示了良好潜力:薄膜菌落总数降低约93.93%。因此,较低能率的等离子体处理能够有效改善薄膜的包装特性,提高蛋白质稳定性,并增强其表面粗糙度以利于与其他材料复合。

The 30 W low-temperature plasma was used to scan the surface of the whey protein isolate-sodium caseinate-glycerol composite protein films for 0,5,10,15 and 20 min.The effects of protein secondary structure,microscopic morphology,surface water-oil affinity,mechanical properties,barrier properties,thermal stability and sterilization ability of films were studied.The results showed that after plasma treatment for 5-10 min,the structure,the degree ofα-helix andβ-sheet in the secondary structure of the protein increased about 15%.In addition,the surface of the film became denser,rougher and showed less porous,and the glass transition temperature(T_(g))rose to 150.60℃,decomposition temperature(T_(d))rose to 197.08℃.In terms of packaging performance,the tensile strength increased by 24.10%,the elongation at break decreased by 27.13%respectively.At the same time,the barrier properties of the film increased,and the oxygen transmission rate was reduced to 1.20 cm^(3)/(m^(2)·d),the water vapor transmission coefficient was reduced to 5.555×10^(-12) g·cm/(cm^(2)·s·Pa),and the surface hydrophobicity and oleophobicity were significantly reduced due to their apparent changes(P<0.05).Besides,the light transmittance was reduced by 20%,and the water solubility was also slightly reduced.Good potential in the application of film sterilization treatment was showed that the total number of film colonies was reduced by about 93.93%.Therefore,plasma treatment with a lower energy rate could effectively improve the packaging characteristics of the film and the stability of the protein,enhance its surface roughness to facilitate the composite with other materials.