牛、羊乳粉的DSC热学性质比较及掺假分析

为明确羊乳粉、牛乳粉的热学特征，采用差示扫描量热法（differential scanning calorimetry,DSC）对真空冷冻干燥制备的全脂羊、牛乳粉样品以及高比例掺假（75%、50%、25%）和低比例掺假（10%、5%、3%、1%）牛乳粉的混合羊乳粉样品进行热力学分析。结果表明，全脂羊乳粉和全脂牛乳粉在DSC热学指标上存在差异，全脂牛乳粉相比全脂羊乳粉缺失一个脂肪特征熔融吸热峰b，蛋白质熔融吸热峰c峰值温度和热焓值较低，而乳糖熔化分解峰e热焓值较高。对于掺入不同比例牛乳粉的羊乳粉，通过检测是否存在吸热峰b及其热焓值，可判断样品掺假牛乳粉比例是否在25%以下及判断掺入牛乳粉的量；在不同比例掺假样品中检测乳糖熔化分解峰e的焓值可判断羊乳粉掺入牛乳粉的掺假量。因此，DSC技术可以实现对羊乳粉、牛乳粉热学性质的分析和评价，也可作为乳制品行业质量保证和真实性鉴别的潜在分析工具。

Comparative Differential Scanning Calorimetric Analysis of Thermal Properties of Bovine and Goat Milk Powder and Identification of Goat Milk Powder Adulteration with Bovine Milk Powder

The thermal characteristics of whole goat and bovine milk powder, prepared by vacuum freeze drying, and goat milk powder adulterated with different proportions (75%, 50%, 25%, 10%, 5%, 3% and 1%) of bovine milk powder were analyzed by differential scanning calorimetry (DSC). The results showed that there were differences in DSC thermal characteristics between whole goat and bovine milk powder. Compared with whole goat milk powder, whole milk powder lacked the characteristic melting endothermic peak (b) of fat, and had lower protein melting endothermic peak (c) temperature and enthalpy value but higher enthalpy value for lactose melting decomposition peak (e). According to the presence or absence of endothermic peak b and its enthalpy value, we could judge whether goat milk powder was adulterated with bovine milk powder at levels below 25% and determine adulteration levels. In conclusion, DSC can be used for the analysis and evaluation of the thermal properties of goat milk powder and milk powder and can also be used as a potential tool for quality assurance and authenticity identification in the dairy industry.