Effects of Pasteurization Method on Lactose

Abstract

In response to claims that lactose-intolerant people were able to drink milk pasteurized utilizing the low temperature, long time method, it was decided to conduct a study comparing the lactose levels in milk pasteurized with two different methods: low temperature, long time (145 degrees F for 30 minutes) and high temperature, short time (165 degrees F for 15 seconds). It was hypothesized that there would be higher available lactose levels in the milk pasteurized with high temperature, short time method. Milk from Autumnwood Farm, a local creamery that pasteurizes with the low temperature, long time method, was used. Raw milk was also collected at the same time and pasteurized in small batches at the high temperature, short time method requirements. Milk samples were analyzed with a colorimeter to determine if browning was evident. After sample clean up and Megazyme Lactose and D-Galactose kit preparation, the lactose and D-galactose levels were determined with a spectrometer. Samples were prepared and run through high-performance liquid chromatography. First round results showed minimal differences with the colorimeter; varying largely based on homogenization rather than pasteurization. Spectrometer and HPLC results did not show differences in lactose concentrations in the various samples. Further research will be conducted to see if there are differences in milk protein, to see if the Maillard reaction has changes on the lactose.