Augusta Lujerdean


SEASONAL RELATED CHANGES IN THE MAJOR NUTRIENTS OF BOVINE MILK (TOTAL PROTEIN, LACTOSE, CASEIN, TOTAL FAT AND DRY MATTER)

Augusta Lujerdean, Andrea Bunea, Vioara Miresan

Abstract
The objective of this study was to analyse the chemical composition of cow milk for an entire year to provide fundamental information for dairy products making and milk cheese yielding. So an investigation of seasonal changes of major nutrients of dairy milk was performed over 12 months beginning in January 2007. Samples were collected weekly from bulk milk shipment in a commercial dairy products company and analyzed for content (%) of total protein, fat, casein, lactose and dry matter. The parameters determined were of interest both from a nutritive and technological point of view. The mean protein content was 3,21±0,10%, lactose 4,87±0,08%, the fat content 3,58±0,07%, casein 2,58±0,10% and dry matter 12,20±0,11%. The relationship of these parameters to season was assessed. The highest and lowest values were observed during winter and summer months respectively.

Key words: cow milk, nutrients, total protein, casein, lactose, fat, dry matter

MODIFICARILE SEZONIERE ALE NUTRIENTILOR MAJORI DIN LAPTELE DE VACA (PROTEINA TOTALA, LACTOZA, CAZEINA, GRASIMEA SI SUBSTANTA USCATA)

Augusta Lujerdean, Andrea Bunea, Vioara Miresan

Rezumat
Obiectivul acestui studiu a fost acela de a determina compozitia chimica a laptelui pe parcursul unui an, informatiile rezultate urmānd a fi utilizate de procesatorii de produse lactate. S-au urmarit modificarile concentratiei nutrientilor majori din laptele de vaca īncepānd cu luna ianuarie 2007. Probele au fost colectate saptamīnal din tancul izoterm al unitatii si s-au analizat urmatorii parametrii: proteina totala, grasimea, cazeina, lactoza si substanta uscata. S-au obtinut urmatoarele valori (%): proteina 3,21±0,10%, , grasime 3,58±0,07%, cazeina 2,58±0,10%, substanta uscata 12,20±0,11%. Se constata dependenta valorilor individuale ale acestor parametri de anotimp cu maxime iarna si minime īn lunile de vara.

Cuvinte cheie: lapte de vaca, nutrienti, proteina totala, cazeina, lactoza, grasime, substanta uscata