鱼翅干制品品质的ATR-FTIR鉴别研究

采用衰减全反射-傅里叶变换红外光谱法(ATR-FTIR)对64份鱼翅干制品(包括真鱼翅、仿鱼翅和素鱼翅)及明胶增重真鱼翅干制品进行快速无损检测鉴别。实验比较了上述四种样品的特征红外光谱图，结果显示，同一种样品的红外光谱具有较好的稳定性;四种鱼翅干制品的红外光谱图存在明显的差异，主要表现在蛋白质酰胺Ⅰ和Ⅱ峰(1 650, 1 544 cm-1)和多糖骨架(1 050 cm-1)等营养成分吸收峰的差异。真鱼翅样品由于蛋白质含量高、多糖组分含量较低，故其红外光谱图主要呈现强度较高的蛋白质特征吸收酰胺Ⅰ和 Ⅱ峰(1 650, 1 544 cm-1)与较弱的多糖骨架C—O—C伸缩振动峰(1 050 cm-1)，前者峰面积和(A_pro)与后者峰面积和(A_pol)的比值(A_pro/A_pol)范围为5.58～25.38。仿鱼翅样品是由鲨鱼的边脚料、胶体及其他一些物质混合、压模而成的，其他添加物质导致减弱了蛋白质特征吸收酰胺Ⅰ和Ⅱ峰的强度，也使酰胺Ⅰ峰发生了约30 cm-1的蓝移，A_pro/A_pol范围为2.63～2.86。素鱼翅样品主要是由海藻酸钠等多糖类物质合成的，其红外光谱图上几乎不显示蛋白质的特征峰，而多糖的特征峰(～1 047 cm-1)表现明显，高于真鱼翅相应吸收峰的强度，A_pro/A_pol范围为0.60～0.72。真鱼翅样品涂覆明胶增重后，样品表面的红外光谱图显示蛋白质和多糖的特征峰均有所减弱，A_pro/A_pol值为1.16，而样品剖面的红外光谱图则与真鱼翅的谱图基本一致。可见，采用ATR-FTIR，利用样品间特征红外光谱图和A_pro/A_pol值的差异，可简便、快速、直观地实现鱼翅干制品品质的无损快速鉴别。

Attenuated Total Reflection-Fourier Transform Infrared Spectroscopic Study of Dried Shark Fin Products

Sixty-four pieces of shark fin dried products (including real, fake and artificial shark fin products) and real products coated with gelatin were rapidly and nondestructively analyzed by attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR). The characteristic of IR spectrograms among the above four kinds of samples were systematically studied and comparied, the results showed that the spectrograms of the same kind of samples were repeatable, and different kinds of shark fin products presented significant differences in the spectrograms, which mainly manifested as the specific absorption peaks of amido bonds in protein (1 650, 1 544 cm-1) and skeletal vibration in polysaccharide (1 050 cm-1). The spectrograms of real shark fins were characterized by the strong absorption peaks of protein characteristic amide Ⅰ and Ⅱ absorbent (1 650, 1 544 cm-1) and relatively weak C—O—C vibration absorbent (1 050 cm-1) owing to the high content of protein and relatively low level of polysaccharide. For fake shark fin products that were molded form by mixing together with the offcut of shark, collagen and other substances, the introduction of non-protein materials leaded to the weaker amido bonds absorbent than real products along with a 30 cm-1 blue shift of amide Ⅰ absorbent. Opposite to the real sample, the relatively strong absorption peak of polysaccharide (～1 047 cm-1) and barely existed amide absorbent were the key features of the spectrogram of artificial samples, which was synthersized by polysaccharide like sodium alginate. Real samples coated with gelatin, the peak strength of protein and polysaccharide were decreased simultaneously when the data collection was taken at the surface of sample, while the spectrogram presented no significant difference to real samples when the data was collected in the section. The results above indicated that by analyzing the characteristic of IR spectrograms and the value range of A_pro/A_pol collected by ATR-FTIR method could perform the undamaged and rapid identification for shark fins.