Table 1.

Impact of different thermal treatment techniques on milk and yogurt properties affecting flavor and texture.

Milk Treatment	Treatment Description	Effect on Milk	Effect on Yogurt
Thermalisation	Heating at 60–69 °C, for 20–30 s	Death of non-heat resistance bacteria.	No significant effect.
		Inactivation of several enzymes [4].	Characteristics affected by further processing [4].
Low Pasteurization	Heating at 63–65 °C for 20 min/at 72–75 °C for 15–20 s (HTST)	Death of most pathogens, vegetative bacteria, yeast and molds.	Slight increase in viscosity and firmness [1].
		Several enzymes denatured, denaturation of several whey proteins [4].
High Pasteurization	Heating at 85 °C for 20–30 min/at 90–95 °C for 5 min	Death of most vegetative microorganisms, except spores.	Large increase in viscosity and firmness [1].
		Deactivation of most enzymes.
		Denaturation of most whey proteins.
		Development of “cooked” flavor [4,18].
Sterilization	Heating at 110 °C for 30 min/at 130 °C for 40 s	Extermination of all microorganisms.	Incorporation of whey proteins into casein matrix. Very large increase in viscosity and firmness [1,4].
		Deactivation of most enzymes.
		Denaturation of whey proteins and aggregation of caseins (casein micelles) and MFG.
		Weakening of flavor intensity.
		Color darkening [4,18].
Ultra Heat Treatment (UHT)	Heating at 145 °C for 1–2 s	Extermination of all microorganisms.	Medium increase in viscosity and firmness [1].
		Mild flavor deterioration.
		Denaturation of whey proteins (β-lactoglobulin, serum albumin, several immunoglobulins)
		Development of off-flavors.
		Color darkening [4,18].