THE FREE D-ASPARTIC ACID AND D-GLUTAMIC ACID CONTENT OF SHEEP MILK AND SHEEP MILK PRODUCTS
J. Csanádi, J. Csapó, J. Fenyvessy, A. Jávor, O. Bara-Heczegh
The role of D-amino acids of foods in the human health is a strongly discussed topic and usually, data came from the investigation of cow milk. We have studied the free D-aspartic acid and free D-glutamic acid content of sheep milk, heat-treated sheep milk at various temperatures and various products of sheep milk. Raw sheep milk didn’t contain free D-aspartic and D-glutamic acid in remarkable amount and ratio 5.92% free D-aspartic acid; 2.62% free D-glutamic acid). Our heat-treatments didn’t cause major change in the free D-aspartic and D-glutamic acid content (max.: 7.8% free D-aspartic acid; 5.3% free D-glutamic acid in total free aspartic and glutamic acid). Contrary, all of the investigated products contained high level of free D-amino acids. The free D-aspartic acid and free D-glutamic acid content of the products were 16,9-39,5%,and 13,3-27% in the percent of total free amino acids. The racemization of aspartic acid was higher, than that of glutamic acid in every product. The D-amino acid content of fermented milk products was higher than in different cheeses.
Keywords: free D-aspartic acid, free D-glutamic acid, sheep milk, dairy products