Viscosity of sweetened condensed milk concentrates: effects of preheat treatment applied during powder manufacture

The viscosity of laboratory-prepared 73% total solids (TS) reconstituted sk im (26% milk solids non-fat, MSNF : 47% sucrose) and 74% TS recombined full -cream (20% MSNF: 8% fat : 46% sucrose) sweetened condensed milk concentrat es was examined as a function of the preheat treatment applied during skim milk powder manufacture and date of powder manufacture. The preheat treatme nts applied to skim milk during powder manufacture were 72 degreesC for 30 s, 75 degreesC for 2 min, 80 degreesC for 30 s or 1, 2 or 5 min, 85 degrees C for 2 or 30 min or 90 degreesC for 2 min. Preheat treatment and date of p owder manufacture had significant effects (p<0.05) on the viscosity of both reconstituted and recombined sweetened condensed milk concentrates. Marked increases in viscosity were observed when the extent of whey protein denat uration in the powder was >50%.