Addition of lactose and vitamin C to growth milk reduces the nutritional quality of proteins.

Addition of lactose to growth milk (+20-30 g . L-1) is responsible for an i ncrease in the Maillard reaction which induces a loss in nutritional value of protein and the development of brown compounds. This reaction is further reinforced by the iron-vitamin C mixture, because of the production of fi ee radical species during heat treatment. However, iron supplementation is one of the nutritional interest of growth milk, whereas lactose addition do es not seem to trigger any nutritional benefit for children. Furthermore, d espite the higher iron biodisponibility allowed by simultaneous vitamin C a ddition, it seems better not to add the vitamin C to avoid its interaction with iron. A new UHT growth milli formula, without addition of lactose and vitamin C, has been compared to a formula containing both nutrients and pro duced using the same UHT hear treatment. We provide evidence of a very sign ificant improvement in the protein quality of the new formula as compared w ith the classic growth milk formula, regarding both the early (25 % lower) and advanced Maillard reaction (400 % less), measured as furosine and fluor escence at 330 and 420 nm respectively. Furthermore, whereas the tryptophan and tyrosine contents of the soluble proteins are 30 % lower in the classi c formula than in cow's milli, they are unchanged in the new formula. In co nclusion, we demonstrate that omission of lactose and vitamin C enrichment in growth milk allows a protein quality similar to that usually found in co w's milk to be restored, despite the presence of iron. (C) Inra/Elsevier, P aris.