The effect of microwave pasteurization on the composition of milk. II. Vitamin B1, B2, B6, B12 and C, utilizable lysine, lysinoalanine, and hydroxymethyl furfurol content

Abstract

The authors compared the traditional pasteurization procedure with microwave milk pasteurization. They examined water soluble vitamin content (vitamin C, B₁, B₂, B₆ and B₁₂) and utilizable lysine, lysinoalanine and hydroxymethyl furfurol content of heat treated milk samples. After mild pasteurization, vitamin C content of milk hardly changed while during microwave pasteurization it decreased to less than its third value compared to the raw milk. Comparing the composition of raw milk with that of milk pasteurized using the two heat treatment methods, they established that there was a bigger loss of vitamin B₁ of around 30-40% while for the other three vitamins B this decrease was around 10%. Comparing vitamin B content of the two pasteurized milk samples, it was established that there was no important differences between the four vitamins B, therefore they recommend the microwave treatment for the pasteurization of milk. They established that vitamin C suffered a bigger damage during microwave pasteurization. Raw milk and milk pasteurized traditionally and by microwave contained hydroxymethyl furfurol not even in traces, consequently, in this respect the two pasteurization procedures can be considered as equal. Utilizable lysine content of the raw milk was measured to be 0.229%, that of the normal milk was measured to be 0.217%, while that of microwave pasteurized milk to be 0.219%. There is a decrease of only around 4-5% in the utilizable lysine content of the milk samples pasteurized in different ways, which indicates the formation of Maillard reaction products during the heat treatment. Lysinoalanine content remained for all the three samples below the quantification limit of 5 mg/dm³, so no difference in the lysinoalanin content could be evidenced between the three milk samples.