Detection of Glucomacropeptide in Raw Milk Adulterated with Cheese Whey in Ecuador

Abstract

Milk is one of the products that can be adulterated in many ways affecting the quality of this and its derivatives. Glucomacropeptide (GMP) is a protein that is found only in the whey from the production of fresh cheese, enzymatically obtained from the coagulation of casein and which is commonly used to adul-terate fresh or powdered milk. The aim of this study was to determine the adulteration of milk with cheese whey thought a molecular approach, where the glucomacropeptide was collected by sequential precipitation with trichlo-roacetic acid (ATC) and detected by polyacrylamidododecylsulfate gel elec-trophoresis (PAGE-SDS), using samples of fresh milk, intentionally adulte-rated with serum in the proportion of 0%, 1%, 5%, 10% and 15%. The results obtained showed that the detection of glucomacropeptide by electrophoresis was positive in all samples of adulterated milk, evidencing a band of 20.9 kDa in the reading, corresponding to the molecular weight of the GMP, showing that the technique used determines the adulteration in the milk, in a specific and sensitive way, also shows that in the evaluation of physical-chemical and microbiological parameters of milk, there are no significant differences be-tween treatments, except for the pH that tends to decrease as the percentage of serum in the milk increases.