After UHT processing conditions (18 s at 138 °C), a residual activity of 37.1 ± 6.1% was determined in SMUF. Mu et al. (2009) revealed about 40% of the initial activity of a peptidase from P. fluorescens after heating to 140 °C for 20 s in Tris–HCl buffer (25 mm, pH 7.5).