CONICET | Buscador de Institutos y Recursos Humanos

In dairy products, changes in color are associated mainly to Maillard reactions (MR). Such reactions usually occur during processing and storage of food. Many factors influence the extent of MR, such as temperature, water activivity (aw), pH, moisture content and chemical composition of the food system. Browning is desirable in some types of food, while it is undesiderable in sterilized milk products or dried milk products like milk powder, whey powder, etc. Therefore, the aim of this study was to determine the effect of heat treatment, year and season on the color of argentine whole milk powder (WMP) already manufactured. Samples were collected from factories of the Central Dairy Area of Argentina, during different seasons over a period of two years (2000-2001). WMP were manufactured from standardized raw milk, being the heat treatments used of 90-93°C 3min (indirect process) and 105°C - 30sec (direct process). CIELab color parameters were measured with a Byk Gardner 9000 colorimeter using D65 illuminant. According to the ANOVA, main effects (heat treatments, year, season) and/or their interactions were significantly (p<0.05) for color parameters. For WMP processed under direct treatment the lowest L* values were observed (p<0.05) in winter, spring and summer of the second year. For WMP manufactured under direct prosses, the highest a* values and the lowest b* values (p<0.05) were observed in the second year. Significantly higher a* values were observed in summer for both years compared to the other seasons. While significantly lower b* values were observed in summer of the second year compared to summer and spring of the first year. It can be concluded that WMP powder color is influenced by type of thermal process applied and season and year of production. The influence of season and year could be associated to compositional changes in raw milk.

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