甘油添加量对兔皮明胶膜性能与结构的影响

Effect of Glycerol Content on Properties and Structure of Rabbit Skin Gelatin Film

以兔皮明胶为原料制备明胶膜,通过测定不同甘油添加量明胶膜的机械性能、水蒸气透过率、亚基组成及结构,明确了甘油添加量对明胶膜性能与结构的影响。结果表明甘油添加量对明胶膜厚度无显著性影响,而水蒸气透过率随甘油添加量的增加呈现上升趋势。力学性能结果表明当甘油添加量达22%(以明胶质量计,m/m)时,明胶膜的抗拉强度和断裂伸长率均显著增加(P<0.05)。十二烷基硫酸钠-聚丙烯酰胺凝胶电泳分析显示甘油并没有导致明胶分子的降解和聚集,膜内结构较稳定,并且当甘油添加量为30%时,膜的谱带强度增加,明胶膜有较高的抗拉强度。傅里叶变换红外光谱分析结果表明随甘油添加量增加,酰胺A带吸收峰逐渐向低波数移动(3 446.9~3 398.9 cm^(-1)),说明甘油分子进入到膜基质,与明胶分子侧链的N—H基团相互反应形成氢键;酰胺Ⅰ带曲线拟合结果表明随甘油添加量的增加,膜内无规卷曲含量逐渐减少,而三螺旋结构含量逐渐增加,说明甘油的添加可促进明胶膜形成更有序的空间结构,进而提升明胶膜的成膜性能和力学性能。

The effect of glycerol concentration on the properties and structure of rabbit skin gelatin film was studied by measuring its mechanical properties, water vapor permeability, subunit composition and structure. The results showed that glycerol concentration had no significant effect on thickness, and the water vapor permeability of gelatin film increased with glycerol concentration. Tensile strength（TS） and elongation at break（EAB） significantly increased（P〈0.05） when glycerol content was increased to 22%. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis（SDS-PAGE） indicated that gelatin molecules did not degrade or aggregate and the band intensity and tensile strength of gelatin film increased when glycerol concentration was 30%. FT-IR analysis showed that amide A band moved to low wave numbers（3 446.9–3 398.9 cm^-1）, which indicated that glycerol molecules reacted with NH groups in peptides to form hydrogen bonds in film matrix. Curvefitting of amide I band showed that random coil decreased while triple helix increased gradually with glycerol concentration, suggesting that glycerol promoted gelatin film to form an ordered structure and in turn to improve its film-forming and mechanical properties.