马哈鱼鱼皮明胶提取温度和甘油质量浓度对其成膜特性的影响

明胶提取温度和甘油质量浓度是影响明胶膜性质的基本因素。本研究以马哈鱼（Oncorhynchus keta） 鱼皮为原料，采用不同温度（40、50、60、70、80、90 ℃）提取明胶，考察不同甘油质量浓度（1.1、1.2、 1.5 g/100 mL）下明胶膜的厚度、机械性能、光学性质、微观结构和红外特性。研究发现，40、50、60 ℃明胶 膜的厚度高于70、80、90 ℃明胶膜的厚度（P＜0.05）。50、60 ℃膜的拉伸强度（tensile strength，TS）高于 70、80、90 ℃膜的（P＜0.05）；添加1.5 g/100 mL甘油，膜的断裂伸长率随提取温度升高而上升（P＜0.05）； 50、70、80 ℃膜的TS随甘油质量浓度升高而下降（P＜0.05）。色差分析表明，膜的a*值随提取温度升高而上升 （P＜0.05）。水蒸气透过率随提取温度和甘油质量浓度的升高而升高（P＜0.05）。明胶膜于200、280 nm波长处 的透光率为0.00%，350～800 nm范围内的透光率为46.53%～74.57%，60 ℃膜的透光率低于40、50 ℃膜的透光率 （P＜0.05）。衰减全反射傅里叶变换红外光谱分析表明膜的图谱呈现典型酰胺A、B、Ⅰ、Ⅱ、Ⅲ带，酰胺A带随 提取温度的升高向低波数移动，且振幅随甘油质量浓度升高而增加。扫描电子显微镜结果显示，膜的截面和表面未 呈现明显断裂或空隙。以上结果表明，温度对马哈鱼鱼皮明胶膜的机械性能、透水性、颜色、透光率影响显著，甘 油质量浓度仅对前二者影响显著，可通过优化提取温度与甘油质量浓度改善马哈鱼鱼皮明胶膜性质。

Effects of Extraction Temperature of Chum Salmon (Oncorhynchus keta) Skin Gelatin and Glycerol Content on Its Film-Forming Properties

Extraction temperature and glycerol content are the critical factors affecting gelatin film properties. In the present study, chum salmon (Oncorhynchus keta) skin gelatin was extracted at different temperatures (40, 50, 60, 70, 80 and 90 ℃), and the effect of glycerol content (1.1, 1.2 and 1.5 g/100 mL) on gelatin film properties including thickness, mechanical properties, color, optical properties, microstructure and infrared absorption characteristics was explored. Results indicated that films of gelatin extracted at 40, 50 and 60 ℃ showed higher thickness than films of gelatin extracted at 70, 80 and 90 ℃ (P < 0.05). Mechanical analysis showed that tensile strength (TS) of films of gelatin extracted at 50 and 60 ℃ was higher than that of films of gelatin extracted at 70, 80 and 90 ℃ (P < 0.05). Elongation at break (EAB) of films with 1.5 g/100 mL glycerol increased with the increase of gelatin extraction temperature (P < 0.05). TS of films prepared from gelatin extracted at 50, 70 and 80 ℃ declined with the increase of glycerol content (P < 0.05). The a* value of films increased with the increase of gelatin extraction temperature (P < 0.05). Water vapor permeability (WVP) showed an increase with the increase of extraction temperature and glycerol content (P < 0.05). The light transmittance of films were 0.00% at wavelengths of 200 and 280 nm and 46.53%–74.57% in the range of 350–800 nm. The light transmittance of films prepared from gelatin extracted at 60 ℃ was lower than that of films prepared from gelatin extracted at 40 and 50 ℃ (P < 0.05). Attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR) analysis demonstrated that gelatin films exhibited the characteristic absorption regions of gelatin, including amide I, II and III bands and amide A and B bands. Among them, amide A shifted to lower wavelength with the increase of extraction temperature and its amplitude increased with increase of glycerol content. Scanning electronic microscopy showed no distinct crack or gaps on the surface and cross section of films. The results indicated that extraction temperature had a significant impact on mechanical properties, WVP and color of gelatin films. However, glycerol content only affected mechanical properties and WVP. Thus, the properties of films prepared from chum salmon skin gelatin can be improved by optimizing gelatin extraction temperature and glycerol content.