content remained without changes compared to the content found in
raw milk. On the contrary, some changes in the retinol contentwere observed;
the UHPH-treated milk s with Ti=45 and 55 °C presented similar
retinol contents than raw milk, while UHPH-treated milks with
Ti=65, 75 and 85 °C and those heat-treated samples presented a slight
but significant (P b 0.05) reduction in the retinol content, compared to
raw milk.
In general, the liposoluble vitamins of milk have demonstrated to be
more thermal resistant than the hydrosoluble vitamins (Fennema,
1996). For this reason, minor changes in this group of vitamins after
the treatments applied can be expected. Even though the UHPH treatment
causes a decrease in the fat globule size due to mainly mechanical
effects in the homogenization valve (Hayes & Kelly, 2003a; Pereda et al.,
2007), it seems to have no effect on the liposoluble vitamins detected in
the lipid fraction of the milk fat globule.