DIFFERENTIATION BETWEEN MILK POWDERS IN RELATION TO PROTEIN OXIDATION AND ANTIOXIDANT

D. SCHEIDEGGER; P. M. RADICI; N. S. BOSIO; V. A. VERGARA-ROIG; S. F. PESCE; R. P. PÉCORA; J. C. P. ROMANO; S. C. KIVATINITZ

JOURNAL OF DAIRY SCIENCE

AMER DAIRY SCIENCE ASSOC-ADSA

Lugar: Champaign, Illinois; Año: 2012

0022-0302

The objective of the present research was to test if commercially available milk powders could be differentiated by their protein oxidative modifications as well as antioxidant capacity, and if these characteristics were related to physical quality parameters such as dispersibility or stability during storage. Fifteen commercially processed spraydried milk powders were employed: six whole milk powder (WMP), four skim milk powder (SMP) and five infant formulae (IFP). Protein oxidative status was measured as protein carbonyl (PC), dityrosine content and extent of protein polymerization. The level of PC was slightly lower in SMP than in WMP, while IFP had more than twice PC that WMP (2.8 ± 0.4; 2.1 ± 0.2 and 6.5 ± 1.3 nmol/mg protein for WMP, SMP and IFP respectively). No differences were detected in dityrosine accumulation. While all the possible pairs of parameters were tested for correlation between them, it was found that four of them were linked: PC, whey content, protein aggregate level and dispersibility. After nine months of storage at -20 ºC (CS) or at room temperature (WS) all milk samples were analyzed to evaluate changes in protein oxidative status (PC, dityrosine and protein integrity) as well as the linked parameters. Milk powders stored had increased PC and idecreased dispersibility when compared to initial conditions. Our results denote the importance of protein oxidative status in milk powder and its relationship to other quality parameters closely linked such as protein integrity and dispersability and suggest that the understanding of such relationships could contribute to develop quality differentiation between different types of milk powders.