Changes in available lysine contents during manufacture of evaporated milk

Roskosz, A.; Brezina, P.; Dolezalek, J.; Prikryl, F.

Prumysl Potravin 30(6): 342-343


Samples of milk (i)-(iv) delivered from 4 delivery routes to the Hlinsko dairy factory in Czechoslovakia; of (v) bulk raw milk from the holding tank standardized to 3.7% fat; of (vi) standardized milk after addition of Na2HPO4 at 1.5-2 kg/t; of (vii) milk after heat treatment at 112 deg C for 3 min; of (viii) milk after concentration on 3-stage Holvrieka evaporator and 2-stage homogenization at 60 deg C and 4.91 and 17.7 MPa resp.; and (ix) of milk after cooling to 10 deg C, standardization of TS content, addition of stabilizing salts, and treatment in 170-g tins by continuous sterilization in an IMC installation at 116 deg C for 10-11 min (the final 'Tatra' product containing 31.1 TS and 9.20% fat were examined for available lysine by the method of Carpenter (Biochemical Journal (1960) 77 (3) 604) and by customary methods for composition. Data tabulated for density, titratable acidity, pH, contents of TS, fat, protein (N X 6.38) and available lysine include the following available lysine values for (i)-(ix): 7.48, 6.87, 7.68, 7.23, 7.48, 7.44, 7.20, 6.97 and 6.23 g/16 g N. Calculated nutritive values of protein based on available lysine losses are also presented for (v)-(ix), (v) being taken as 100%.