Color characteristics of raw milk from silage and alfalfa-fed cows

LANGMAN, L.,; ROSSETTI, L.; A.M. SANCHO; COMERON, E; DESCALZO, A; GRIGIONI G

Mar del Plata

Congreso; AIC Interim Meeting 2010. Color and Food: from the farm to the table; 2010

International Color Association

Food color is the result of natural products associated with the raw material from which it is processed and / or colored compounds generated as a result of processing. It is influenced by how the food matrix interacts with light. The white appearance of milk is the result of its physical structure. The casein micelles and fat globules disperse the incident light and, consequently, milk exhibit a high value of parameter L*. The other color parameters (a* and b*) are influenced by factors related to natural pigment concentration of milk. Carotenoids pigments are related to the yellowness of milk, being this characteristic associated with b* parameter. Forage diets improved the content of carotenoids and vitamins in milk when compared to grain-based diets. The experiment was conducted during spring (October to December) at the National Institute of Agricultural Technology in Rafaela (Argentina). During a first four-week pre-experimental period, ten Holstein cows were fed on a silage-only diet (SS) with at least 50% of forage; this diet also contained soy expeller and sunflower pellets (3.5 and 1.1 kg/day per cow, respectively) and hay (1.5 kg/day per cow). Thereafter, five cows were randomly assigned to an alfalfa diet (ALF, at least 60% alfalfa of dry matter on dietary basis) while another group remained as control, during 60 experimental days. At each measure time, CIELab parameters were recorded using a reflectance spectrophotometer (BYK Gardner Color View model 9000), with large port area (5 cm diameter) and D65-artifitial daylight. As regards of b* component, raw milk corresponding to the alfalfa-based diet showed significant differences at 60 days after implementing the diet. These samples presented higher b* values, which indicates a more yellow color. No significant differences were observed for L* parameter.