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Vitamins A and D are added to milk to

enhance its nutritional profile. Since milk is

a common food in most Americans’ diets,

supplementation of vitamin D has helped

to reduce the prevalence of rickets and

other bone weakening conditions since

supplementation began. Whole milk

naturally contains vitamin A and some

vitamin D, but must be supplemented in

low-fat products.

Homogenization is a mechanical process;

milk is pumped through fine holes

under high pressure to decrease milk

fat globule size. Because fat is less

dense than water, fat separates and

rises to the top of milk that is not

homogenized. Breaking milk fat

into smaller globules helps create

a smooth, uniform and appealing

texture. This process has no effect

on the nutritional quality of milk.

Pasteurization is the process of

heating raw milk at a high enough

temperature for a sufficient length of

time to make milk bacteriologically

safe – destroying dangerous

microorganisms which can grow in

milk. Pasteurization has little to no

effect on milk’s nutritive value.

Raw Milk

Add Vitamins

Packaging

Cooling

Pasteurization

Homogenization

Separator

Skim MilkCream

**Diagram adapted from Patton, Stuart. Milk. New Brunswick: Transaction Publishers, 2004. Print.

IS MADERaw milk from a dairy cow is processed for safety and ease of use.

The aroma, flavor and texture of yogurt can vary depending on the type of milk and culture, the amount of milk fat/nonfat milk solids, fermentation process and temperature used.

Start with milk

Whole, reduced fat, lowfat or nonfat.

Homogenization

The milk (plus optional nonfat solids) is homogenized

prior to “setting” to prevent separation of the fat.

This helps to create a smooth finished product.

Pasteurization

Milk is pasteurized to destroy milk-

borne pathogens.

Cooling and addition of healthy bacteria. Milk is

cooled after pasteurization, then Lactobacillus bulgaricus

and Streptococcus thermophilus are added and incubation

begins. The primary function of these harmless cultures is to

convert milk sugar (lactose) into lactic acid.

NOTE: Some yogurts, like fruit on the bottom yogurt,

have fruit/flavorings added prior to incubation.

Incubation is the setting phase. It serves to promote

the growth of cultures and thus, the

production of lactic acid. This acid

lowers the pH of the mixture,

changing the structure

of the proteins (namely

casein) in milk, and the

resulting “coagulated” milk

product, yogurt, is formed.

Optional Ingredients Added Other ingredients – such

as fruits and flavorings – are

stirred in prior to packaging.

Milk(Plus optional nonfat

solids for added firmness)

Homogenization

Cooling

Pasteurization

Incubation

Other Ingredients **Diagram adapted from Patton, Stuart. Milk. New

Brunswick: Transaction Publishers, 2004. Print.

© 2016 Western Dairy Association. May not be reproduced without permission from Western Dairy.