Polymer Materials Research Department, Advanced Technology and New Materials Research Institute, CSRAT, New Boarg El-Arab City, 21934 Alexandria Egypt.
Proteins Research Department, Genetic Engineering and Biotechnology Research Institute, CSRAT, New Boarg El-Arab City, 21934 Alexandria Egypt.
J Food Sci Technol. 2014 Oct;51(10):2425-34. doi: 10.1007/s13197-012-0792-y. Epub 2012 Aug 14.
Pure zein is known to be very hydrophobic, but is still inappropriate for coating and film applications because of their brittle nature. In an attempt to improve the flexibility and the antimicrobial activity of these coatings and films, Chemical modification of zein through forming Schiff bases with different phenolic aldhydes was tried. Influence of this modifications on mechanical, topographical, wetting properties and antimicrobial activity of zein films were evaluated. The chemical structure of the Schiff bases films were characterized by ATR-FTIR spectroscopy. The results indicate an improvement in mechanical properties with chemically modification of zein to form Schiff bases leading to a reduction in the elastic modulus. An increase in the elongation at break has been observed, but with slight influence on tensile strength. Plasticized zein films have similar initial contact angle (∼40°). An increase in reaction temperature and time increases film's affinity towards water. As shown by contact angle measurements, a noticeable relation was found between film composition and the hydrophilicity. Surface topography also varied by forming Schiff bases, becoming rougher than zein-based films. The antibacterial activities of zein and Schiff bases of zein-based films were investigated against gram-positive bacteria (Listeria innocua, Listeria monocytogenes, Bacillus cereus and Clostridium sporogenes) and gram-negative bacteria (Escherichia coli, Yersinia enterocolitica and Salmonella enterica). It was found that the antibacterial activity of the Schiff bases-based films was more effective than that of zein-based films.
纯玉米醇溶蛋白是众所周知的非常疏水，但由于其脆性，仍然不适合用于涂层和薄膜应用。为了提高这些涂层和薄膜的柔韧性和抗菌活性，尝试通过与不同酚醛醛形成席夫碱来对玉米醇溶蛋白进行化学修饰。评估了这种修饰对玉米醇溶蛋白膜的机械性能、形貌、润湿性和抗菌活性的影响。通过衰减全反射傅里叶变换红外光谱（ATR-FTIR）对席夫碱膜的化学结构进行了表征。结果表明，通过化学修饰玉米醇溶蛋白形成席夫碱可以改善其机械性能，从而降低弹性模量。观察到断裂伸长率增加，但对拉伸强度的影响较小。增塑玉米醇溶蛋白膜具有相似的初始接触角（约 40°）。反应温度和时间的增加会增加薄膜对水的亲和力。如接触角测量所示，发现薄膜组成与亲水性之间存在明显关系。表面形貌也因形成席夫碱而发生变化，变得比基于玉米醇溶蛋白的薄膜更粗糙。研究了玉米醇溶蛋白和玉米醇溶蛋白席夫碱基薄膜对革兰氏阳性菌（无害李斯特菌、单核细胞增生李斯特菌、蜡状芽孢杆菌和产气荚膜梭菌）和革兰氏阴性菌（大肠杆菌、肠炎沙门氏菌和肠炎耶尔森菌）的抗菌活性。结果发现，席夫碱基薄膜的抗菌活性比基于玉米醇溶蛋白的薄膜更有效。
