Sleepyjack

How come butter goes so hard in the fridge, whereas margarine stays quite spreadable?

I never got into much organic chmeistry, so i am not sure about all the poly and mono (un)saturated fats, or if that has anything to do with it?

Also what are some fundamental differences betwen margarine and butter? Is it something to do with the different fats used, like vegatble and or animal? i was never too sure about this?

thanks

saltfish

Any fat that is solid or mostly-solid at room temperature has a higher concentration of saturated fat.

Unsaturated
<IMG src="http://www.eng.auburn.edu/users/wfgale/usda_course/section0_images/section0_images_4/unsaturated_fat.gif"</IMG>

Saturated
<IMG src="http://www.eng.auburn.edu/users/wfgale/usda_course/section0_images/section0_images_4/saturated_fat.gif"</IMG>

What you see here is that the unsaturated fat has far less Hydrogens and that there are more double bonds. An unsaturated fat solution is usually liquid at room temperature, whereas a saturated fat is solid at room temperature.

Butter, by law must be an exact number,80%, margarine must also be that same percentage to be called margerine. When you start talking about spreads and stuff that comes in 'crocks' you are looking at a higher water percentage.

Mainly what you will see with margerines, as well as other spreads is the use of corn/soy oils that have been 'hydrogenated' these fats have been exposed chemicially to a substance that 'adds' hyrdogens to their composition, turning them into a higher degree of saturation. Thus making them solid at room temperature. Other tricks that have been used in the past is using a lecethin to suspend more water into the fat so they do not seperate. This helps to lower costs on the producers end. One consequence to hydrogenating fats is that they're strands can twist, thus creating the dreaded 'trans-fat" <-- bad stuff.

Main differences between butter and margerine.

Butter must come from milk, must contain 80% milk-fats

Margarine- origionally developed to use beef fat and milk to make a spread similar to butter, it is not mainly comprised of vegetable oils, water and salt. Some margerines contain up to 50% water, and must be labeled as 'spread'

Other fats like- lard, seut are animal based and contain high levels of both cholesterol as well as saturated fat.

Other yummy fats: Safflower, Coconut, cottonseed, palm kernel, all of which have a great concentration of saturated fat, but they're soo darn tasty!!

I can keep goin!!

-SF

sipsake

Holy cow...that's a lot of info. So, if Marlon Brando had used for margarine instead of butter in Last Tango in Paris, it wouldn't have made much difference.

Oh...don't forget olive oil, it's a pretty yummy fat.

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Sapper

Eek!! I see lots of trans-fats in the above example

The low-down.

If all the "fat tails" are straight, they can pack in tightly as the fat cools ... allowing the formation of a solid.

If most "fat tails" are bent, the fat can not pack in tightly, maintaining fluidity.

Your cell's plasma membrane uses cholesterol to regulate membrane fluidity (prevents tails from packing in tightly at low temperatures).

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