Discrimination of reconstituted milk and over-processed milk in pasteurized and UHT milk

Abstract Text: The objective of the present study was to distinguish over-processed milk and reconstituted milk by comparing the heat treatment indicators in raw milk, over-processed milk and raw milk plus reconstituted milk under both pasteurized and ultra high temperature (UHT) conditions. The contents of furosine and lactulose, as well as the ratio of lactulose to furosine were investigated. Lactulose was detected using UV spectrophotometer by enzymatic method (ISO 11285/2004) with modifications and furosine was detected by using high-performance liquid chromatography (HPLC) according to ES ISO 18329/2012. The content of furosine was less than 12 mg/100g protein, when the milk was pasteurized from pure raw milk; if the content of furosine was more than 12 mg/100g protein, it can be considered as reconstituted milk when L/F was less than 1, otherwise it could be regarded as over-processed milk when L/F was higher than 1. If it was produced from pure raw milk under UHT conditions, the content of furosine would be less than 140 mg/100g protein; if the content of furosine was more than 140 mg/100g protein, it can be considered as reconstituted milk when L/F was less than 2, otherwise it could be regarded as over-processed milk when L/F was higher than 2. Our results suggest that over-processed milk and reconstituted milk in pasteurized and UHT milk might be differentiated by the content of furosine and the ratio of lactulose and furosine (L/F).

Keywords: reconstituted milk; over-processed milk; lactulose/furosine