基于双波长紫外吸收的乳脂肪快速测定

Rapid Determination of Milk Fat Based on Dual Wavelengths of Ultraviolet Absorption

为便于实施对乳品加工中乳品及管路残留乳脂肪含量的全面监控,建立一种基于双波长紫外吸收的乳脂肪快速定量方法。采用萃取-沉淀操作采集液态乳或加工管壁样本中的乳脂肪并直接测定204 nm和230 nm 2个波长处的吸光度,再基于吸光度差ΔA204 nm-230 nm和乳脂肪标准曲线方程可确定样本中的乳脂肪含量。对于液态乳品样本,该方法的变异系数不大于3%,回收率在95.6%~102.9%之间,并可有效避免乳品热处理差异的干扰。此外,该方法也可成功用于不同加工条件下乳品加工管路中乳脂肪管壁残留量的测定。

To facilitate the comprehensive monitoring of milk fat content in dairy products or pipeline residues throughout the dairy processing, a rapid assay for milk fat based on dual wavelengths of ultraviolet absorption was developed. Milk fat was recovered from samples of liquid dairy or dairy processing pipe wall with a extraction-precipitation operation and the absorbance at 204 nm and 230 nm of the milk fat extract was detected. The milk fat content could be calculated with the standard curve equation from the difference between absorbance at 204 nm and 230 nm. In this way, the interference of various heat treatments on samples could be avoided. It was verified that the variation coefficients were less than 3%and the recoveries ranged from 95.6% to 102.9% for liquid dairy samples. In addition, the method led to reliable results in determining milk fat residues in pipe wall under various dairy processing conditions.