How sour cream is made
Sour cream is cream that bacteria thicken in about 18 hours, until its pH falls from 6.5 to 4.6.
- stations
- 7
- things upstream
- 2
- raw source
- 1
- steps from the ground
- 2
The short version
Dairies adjust cream to the right fat level, stir in stabilizers, homogenize it so the fat droplets are tiny, and pasteurize it. Then they cool the cream, add lactic acid bacteria and leave it to ferment for about 18 hours in the tub. The acid thickens the cream, and it is chilled before it ships.
-
Set the fat level
Cream is standardized so the finished product meets the legal minimum. In the United States that is at least 18 percent milk fat before any bulking ingredients are added.
at least 18% milk fat
-
Stir in stabilizers
Whey solids and stabilizers such as modified starch, guar gum or carrageenan go in. They give a smooth gel and help stop the watery layer that can weep out of the tub when it gets shaken in transit.
-
Break the fat into specks
A homogenizer forces the cream through a narrow gap so the fat globules shatter into specks below 2 microns. Smaller globules make a thicker, whiter, creamier product that does not separate.
-
Pasteurize the cream
Heat kills harmful bacteria and clears the field for the starter culture. It also denatures whey proteins, and those stick to the fat globules and add to the thick texture.
-
Cool and add culture
The cream is cooled to a temperature where mesophilic bacteria thrive and seeded with a small dose of active starter culture, 1 to 2 percent of the batch.
20 °C
-
Let it sour in the tub
The inoculated cream is portioned into its packages and left to ferment. Bacteria turn milk sugar into lactic acid. At a pH near 4.6 the casein proteins clump into a gel and the cream sets.
18 hours, pH 6.5 to 4.6
-
Chill the sealed tubs
A last cooling stops fermentation. The sealed product must stay refrigerated from then on.
Worth repeating
- Sour cream is only partly fermented, which is why it still has to be refrigerated.
- Milk protein sets into a gel when the pH reaches about 4.6, the same threshold that curdles milk into cheese and yogurt.
- An unopened tub of sour cream can last 1 to 2 weeks past its sell-by date.
Back to the ground
Follow every input upstream and sour cream starts as these 1 raw source.
Keep walking
Sources
Cite this page: "How sour cream is made." Assembly Line, 2026-11-03. https://assemblyline.org/make/sour-cream