PH-cheeses showed the highest content of C16, C18 and C18:1 at
30 and 60 days of ripening. No statistical differences were found
between PA- and UH-cheeses in either of these ripening stages.
Lipolysis in cheese can be produced by natural lipases, such as
LPL or by microbial lipases from the starter and non starter lactic
acid bacteria. The indigenous LPL is nearly completely inactivated
by HTST pasteurization. However, it may contribute to lipolysis in
pasteurized-milk cheeses as a time and temperature combination
of 78 C for 10 s is required for its complete inactivation (Driessen,
1989). Datta et al. (2005) observed that the activation/inactivation
of milk lipase by UHPH depends on the temperature reached with
the treatment. These authors found a total inactivation of the
endogenous LPL in milk UHPH-treated at 200 MPa at outlet temperatures
>71 C. In the present study, the maximum temperature
achieved with the UHPH treatment was around 82 C which was
maintained for a short time (0.7 s), so little or no LPL activity is
expected for all cheeses.