NCN value increased during storage for both skimmed and whole milks, as shown in Fig. 1. Values were
always higher (>99% signi®cance level) for skimmed
milks than for the corresponding whole milks. This fact
could be attributable to a lower enzymatic activity in
whole milk due to a possible protective eect of the fat
against enzymatic attack of the protein, as was reported
by Lo pez-FandinÄ o, Corzo et al. (1993). These authors
found that proteolysis (estimated by SDS-PAGE) was
faster in skimmed milk than whole milk