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I have a quick question: Are triglycerides essentially what we call "fats"? I've tried reading up on it but there seems to be some conflicting information. Thank you.

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  • $\begingroup$ I think "fat" is a word that maybe it is not too recommended to use in an organic chemistry context. What I understand as fat is those "yellowish" and solid compounds, like margarine. In a chemical context fat is often confused with the lipids, which are (be the definition broad) the amphipatic compounds, mainly composed by carbon and hydrogen and that fall in two groups, the ones that can undergo saponification and the ones that cannot. this is consequence of having or not the FATTY acids (C-H chains ended in a carboxy group). $\endgroup$ – Katz Sep 28 '14 at 15:23
  • $\begingroup$ If the fatty acids have a double bond in their C-H chain they are called insaturated, and are often liquid at room temperature. The ones with no double bond are saturated, and are SOLID. If you accept my definition of "fat", saturated triglycerides YES would be FAT, but the others would be not. Thats what I think, but I am not 100% sure $\endgroup$ – Katz Sep 28 '14 at 15:26
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Fats include free fatty acids and their compounds with glycerol: mono-, di- and triglycerides.

In a cooking context, fats refer to solid fats, and oils to fats that are liquid at room temperature. Most of them contain triglycerides.

Fats belong to a broader group--lipids--, which are substances that are usually not soluble in water and usually soluble in certain organic solvents, such as ether or acetone. Besides fats, lipids include sterols (cholesterol, plant sterols), waxes, lipid-soluble vitamins (A, D, E, K) and steroid hormones (aldosterone, corticosterone, etc).

Examples of complex lipids are phospholipids, glycolipids and lipoproteins.

Fats and lipids are often used as synonyms. However, you usually say dietary fats and blood lipids.

http://www2.chemistry.msu.edu/faculty/reusch/VirtTxtJml/lipids.htm http://biology.about.com/od/molecularbiology/ss/lipids.htm

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As far as I know fats are solid lipids while oils are liquid lipids in (I guess) room temperature. So saturated triglycerides are usually fats, and unsaturated triglycerides are usually oils.

This is because saturated and trans-unsaturated fatty acid chains are linear while cis-unsaturated fatty acid chains are curly (non-linear). Forces between linear chains are stronger that's why they are solid after a length.

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