Table 3. Heat treatments of other dairy products used in the dairy industry

Heat treatments (Temperature – time conditions) Applications Bacteria destroyed Significant chemical effects Comments
90°C-95°C/5-10 min Yogurt manufacture Most non-spore-forming bacteria Almost total denaturation of whey proteins (WP) Causes increased viscosity of yogurt through for mation of WP – k-casein complexes and enhanced water binding capacity
72°C-80°C/15-30 s) Low-heat skim milk powder (SMP) Non-spore-forming pathogens and psychrotrophic spoil-age bacteria As for pasteurization; little whey protein denaturation- WPNI>6.0 g/L Product used for recombined milk, milk, standard-isation, cheese manufacture
85°C/1 min; 90°C/30 s; 105°C/30 s Medium-heat SMP.Pre-heating in UHT processing Whole milk powder. Non-spore-forming pathogens and psy-chrotrophic spoil-age bacteria Moderate to substantial whey protein denaturation- WPNI 1.5-6.0 g/L; inactivation of plasmin; Exposure of some sulfhydryl groups and formation of some sulfhydryl compounds which act as antioxidants in whole milk powder Product used for ice-cream, chocolate, confectionery Decreases fouling of UHT plants and reduces plasmin-catalysed proteolysis during storageImproves storage stability of whole milk powder
90°C/5 min; 120°C/1 min; 135°C/30 s High-heat SMP Non-spore-forming pathogens, psychro-trophic spoilage bacteria and most spores at the most severe conditions Extensive whey protein denaturation- WPNI<1.5/L Product used for recombined evaporated milk
>120°C/>40 s High-high-heat or high-heat-high-stable SMP Non-spore-forming pathogens, psychrotrophic spoilage bacteria and most spores Almost complete denaturation of whey proteins- WPNI<<1.5 g/L Product used for bakery products and recombined evaporated milk
Adopted from Deeth & Smithers with CC-BY [4].
WPNI, whey protein denaturation index; indicates level of undenatured whey protein and used to categorize skim milk powders; UHT, ultra high temperature.