Naked Science Forum

Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: chris on 15/10/2011 10:46:22

Title: Why does whipping cause cream to thicken?
Post by: chris on 15/10/2011 10:46:22
What happens when cream is whipped to make it change texture in the way that it does?
Title: Why does whipping cause cream to thicken?
Post by: CliffordK on 15/10/2011 10:53:55
I presume that whipping aerates the cream.

Churning, on the other hand, separates the fats from the buttermilk.  Perhaps a centrifuge would do the same thing.
Title: Why does whipping cause cream to thicken?
Post by: Geezer on 15/10/2011 16:14:37
You can make butter from cream by whipping it in a mixer [:D]
Title: Why does whipping cause cream to thicken?
Post by: Airthumbs on 15/10/2011 23:53:59
The only thing that happened when I whipped my cream is it made a mess all over my leather tassels!  [:P]
Title: Why does whipping cause cream to thicken?
Post by: yor_on on 15/10/2011 23:59:12
Because it hurts?

ahem.

No?

Okay then, it doesn't hurt. maybe :)

Title: Why does whipping cause cream to thicken?
Post by: damocles on 17/10/2011 14:32:58
Cream is an emulsion. Ordinary cream contains fat/oil droplets in water with a protein adsorbed at the interface to stabilize the system.

Whipping the cream incorporates tiny air bubbles into the still colloidal system. But is also disrupts the surface structure of the fat droplets allowing them to link up and form a gel-like structure where both fat and water are continuous phases, but the fatty phase is more solid-like.

Fresh cream:-- water is a continuous phase, fat is in protein-coated discrete nanoparticles.
Whipped cream:-- water and fat are both continuous phases, with a protein coating at the interface. Air is present in discrete microbubbles.

The structure of gels is a little mysterious to many people -- how can you have two continuous phases? Take a cube shaped block from a child's set of blocks, and drill three holes between pairs of opposite faces. If you were to take a large number of such blocks and stack them together, the holes would join up, and both the remaining solid of the blocks and the air in the continuous hole channels would be continuous phases. Most gels do not have such a regular defined structure, and they certainly would not need to have this structure. And with whipped cream the gelation is usually only partial.
Title: Why does whipping cause cream to thicken?
Post by: Pmb on 17/10/2011 16:53:32
Quote from: damocles on 17/10/2011 14:32:58
Cream is an emulsion. Ordinary cream contains fat/oil droplets in water with a protein adsorbed at the interface to stabilize the system.

Whipping the cream incorporates tiny air bubbles into the still colloidal system. But is also disrupts the surface structure of the fat droplets allowing them to link up and form a gel-like structure where both fat and water are continuous phases, but the fatty phase is more solid-like.

Fresh cream:-- water is a continuous phase, fat is in protein-coated discrete nanoparticles.
Whipped cream:-- water and fat are both continuous phases, with a protein coating at the interface. Air is present in discrete microbubbles.

The structure of gels is a little mysterious to many people -- how can you have two continuous phases? Take a cube shaped block from a child's set of blocks, and drill three holes between pairs of opposite faces. If you were to take a large number of such blocks and stack them together, the holes would join up, and both the remaining solid of the blocks and the air in the continuous hole channels would be continuous phases. Most gels do not have such a regular defined structure, and they certainly would not need to have this structure. And with whipped cream the gelation is usually only partial.

Excellent response damocles! :D

Best wishes

Pete
Title: Why does whipping cause cream to thicken?
Post by: Geezer on 18/10/2011 03:45:52
The only problem I have with whipping cream is that it makes my hands slip out of the handcuffs.
Title: Why does whipping cause cream to thicken?
Post by: Phractality on 18/10/2011 08:42:46
Surface tension affects only a small fraction of the volume of a liquid, but a foam is practically all surface, so surface tension dominates.
Title: Why does whipping cause cream to thicken?
Post by: syhprum on 18/10/2011 13:58:41
Mention of cream and whipping seems to awaken strange thoughts in the male mind.