FTIR光谱法与奶粉的品质分析

采用傅里叶变换红外光谱法（FTIR）获得了11种奶粉产品的红外光谱。奶粉中的主要营养成分在红外光谱中具有明显的指纹特征。同一生产厂家不同品牌的奶粉，其脂肪、蛋白质和碳水化合物的相对比例在红外光谱上差异性较显著，不同厂家相同类别的奶粉既有一定的一致性，在添加辅料的类型和用量上又有所不同。奶粉中脂肪含量高的谱图在1747cm^-1附近的C-O吸收峰和2926cm^-1附近的CH2吸收峰很强；蛋白质高的奶粉所对应的酰胺Ⅰ带的C=O吸收峰（1650cm^-1）和酰胺Ⅱ带的N—H及C-N吸收峰（1540cm^-1）强度较大；奶粉中碳水化合物所对应的C-O伸缩振动峰和环的振动峰在1150～900cm^-1范围内较显著。麦芽糊精、蔗糖和乳糖这三种常用辅料同样具有明显的指纹特征。该方法可简便、快速、直观地评价奶粉品质的优劣。

Quality Analysis of Powdered Milk via FTIR Spectroscopy

Eleven kinds of powdered milk were identified by Fourier transform infrared spectroscopy (FTIR). The main nutritious components had distinct fingerprint characteristics in the IR spectra of milk powder. For samples from the same factory but of different brands, there was some dissimilarities in the relative intensities of infrared absorption peaks due to the difference in fat, protein and carbohydrate as well. For the samples of the same sort, but from different factories, there were certain similarities in the IR spectra. The spectra of milk powders with high level of fat, protein, and carbohydrates have their own characteristic absorption prak in the FTIR. Three kinds of commonly used excipients: maltodextrin, sucrose and lactose, all have specific fingerprint features, which change as their amounts alter. The present research provides a fast and direct method for evaluating the quality of powdered milk.