Proteolysis in Mozzarella Cheeses Manufactured by Different Industrial Processes

Evolution of soluble nitrogen values (%SN) for the central points (E1, E9, and E17) of the experimental design during ripening time at 4°C. Fat matter in the cheese milk was 2.9%, stretching temperature was 83°C, and brining time was 18h. ■ = E1, □ = E9; ▴ = E17.

Evolution of soluble nitrogen values (%SN) during ripening at 4°C of 4 pairs of cheeses stretched at 78 or 88°C and brined for 14 or 22h. E2 (■) and E3 (□): stretching temperature 78°C, 14h of brining; E4 (▵) and E5 (▴): stretching temperature 88°C, 14h of brining; E6 (○) and E7 (●): stretching temperature 78°C, 22h of brining; and E8 (+) and E10 (−): stretching temperature 88°C, 22h of brining.

Evolution of soluble nitrogen values (%SN) for the star points of the experimental design during ripening time at 4°C. a) Samples with 2.06 (E11) and 3.74% (E12) of fat content in the cheese-making milk; b) samples stretched at 74.6 (E13) and 91.4°C (E14); c) samples brined for 11.27 (E15) and 24.73h (E16), respectively.

Urea-PAGE of Mozzarella cheese sampled at a) 4, b) 49, c) 91, and d) 131 d of ripening. Fat matter in cheese milk (%), stretching temperature (°C), and brining time (h), respectively, of each cheese was as follows: E1 = 2.9%, 83°C, 18h; E2 = 2.4%, 78°C, 14h; E3 = 3.4%, 78°C, 14h; E = 2.4%, 88°C, 14h; E5 = 3.4%, 88°C, 14h; E6 = 2.4%, 78°C, 22h; E7 = 3.4%, 78°C, 22h; E8 = 2.4%, 88°C, 22h; E9 = 2.9%, 83°C, 18h: E10 = 3.4%, 88°C, 22h; E11 = 2.06%, 83°C, 18h; E12 = 3.74%, 83°C, 18h; E13 = 2.9%, 74.6°C, 18h; E14 = 2.9%, 91.4°C, 18h; E15 = 2.9%, 83°C, 11.27h; E16 = 2.9%, 83°C, 24.73h; and E17 = 2.9%, 83°C, 18h. Cheeses E8 to 17 remained in the ripening room and were also sampled at 131 d (panel d).

Principal component analysis and sample clustering (k-means) of preprocessed data obtained from reverse phase-HPLC chromatograms of the water-soluble fraction of Mozzarella cheeses. Numbers indicate sample and ripening time; different symbols show different cluster membership.