Abstract: In order to explore the potential roles of amino acids as natural plasticizers of gelatin film, we investigated the effect of different amino acids (proline, leucine, glutamate, serine and methionine) on thickness, mechanical properties, water vapour permeability, light transmission, color, and structure of gelatin films. The results showed that amino acids increased except proline the flexibility of the gelatin film compared with the control group except methionine. Amino acids increased except proline the yellowness and reduced the transparency of gelatin film. Gelatin film incorporated with proline showed better flexibility, better surface characteristics with smooth and firm surface, and higher transparency, light transmittance and flexibility than the other amino acids. According to FTIR spectra and secondary structure results, proline, serine and methionine could interact with gelatin chain by hydrogen bond, and the addition of them reduced the random coil structure of gelatin, and increased the content of β-sheet and β-turn structure. These results indicated that proline can be used as natural plasticization of gelatin films, which provided a new perspective for the application of plasticizers in gelatin films.

Key words: gelatin films, amino acids, plasticizer, structure, mechanical properties

摘要： 为了探索氨基酸作为明胶膜增塑剂的潜力,本试验研究了不同氨基酸(脯氨酸、亮氨酸、谷氨酸、丝氨酸和甲硫氨酸)对明胶膜厚度、机械性能、水蒸气透过率、透光率、颜色以及结构等的影响。结果表明,与对照组相比,除了甲硫氨酸外,其余的氨基酸都能增加明胶膜柔韧性;除了脯氨酸外,其余的氨基酸都增加了明胶膜的黄度值,并降低了明胶膜透光率和透明度;而添加脯氨酸的明胶膜的柔韧性最好、具有更好的表观特征,表面光滑紧致,同时具有更高的透明度、透光率和柔韧性。根据傅里叶变换红外光谱和二级结构分析发现,添加脯氨酸、丝氨酸和甲硫氨酸能通过氢键与明胶相互作用,降低明胶的无规则卷曲结构含量,增加β-折叠和β-转角结构含量。综合分析认为,脯氨酸可以作为明胶膜的天然增塑剂。本研究结果为增塑剂在明胶膜中的应用提供了新视角。

关键词: 明胶膜, 氨基酸, 增塑剂, 结构, 机械性能