Lipids Flashcards
What is the classification of the structure of lipids?
Fatty acids are carboxylic acids of various hydrocarbon chains lengths and degrees of unsaturation
Saturation:
Saturated- contain all hydrogen that are capable of
Unsaturated - 1 or more double bonds between carbons. Can have cis/trans configuration
- MUFA (one double bond)
- PUFA (2 or > double bonds)
Length:
- LCFA
- SCFA
Give examples of SCFA (short chain fatty acids)
VFA:
Acetic
Propionic
Butyric
Give examples of PUFAs (polyunsaturated fatty acids)
Omega 3 and omega 6 fatty acids
List some saturated FAs of nutrition significance
Acetic (Rumen VFA)
Propionic (Rumen VFA)
Butyric (Rumen VFA)
Valerie (Rumen VFA)
Caproic (Rumen VFA)
Lauric (palm oil)
Myristic (palm oil)
Palmitic (plant and animal fats)
Stearic (plant and animal fats)
What are TAGs (triacylglycerols)?
Are the esters of 3 fatty acids with glycerol
Which properties of FAs affect the physical nature (liquid/solid) of the TAGs?
Length of the carbon chain
Degree of unsaturation
The shorter the carbon chain and the more unsaturated, the greater the chance to be liquid in a room temperature
List common unsaturated FAs of nutritional significance
Oleic
Elastic
Linoleic
Gama-linolenic
Alfa-linolenic
Arachidonic
Where is cholesterol most abundant: animal fat or muscle tissue?
Muscle tissue (more cell membranes in muscle than adipose tissues)
List some examples of steroids (fat soluble substances)
Cholesterol
Vit D
Bile acids
Sex hormones (androgenic, estrogens, progesterones)
Corticosteroids hormones (cortisol)
Mineralocorticoids (aldosterone)
Which FAs are eicosanoids (prostaglandin, tromboxanes, leukotrienes) synthesized from?
Arachidonic acid (mainly)
EPA
DHA
How is the lipid digestion in non-ruminants?
TAGs are emulsified in the small intestines by the emulsifying activity of bile salts (bile acids) and phospholipids.
Their digestion depends on the hydrolysis of the Ester bonds, in which the pancreatic lipase will take part. It will liberate free fatty acids, diacylglycerols and monoacylglyslcerols. These products will form water-soluble micelles, those will transport the fat-soluble substances to the intestinal surface for absorption
Why ruminants should receive a diet with low concentration of lipids?
In non-ruminants, fats are emulsified by bile before digestion in the intestines
In the rumen, there is a lack of emulsifying agent and pancreatic lipase. If they would receive high fat content, it would lead to decreased fiber digestibility. Also, unsaturated fats are toxic to rumen bacteria.
Which is the most predominant fatty acid in the rumen?
Steric acid (through the biohydrogenation of Linoleic Acid in the rumen)
What are differences between ruminants and non-ruminants regarding the lipids digestion?
Non ruminants: lipids entering the small intestines are in the esterified form
saturated fatty acids are poorly absorbed
Ruminants:
lipids entering the small intestines are FFA (80-90%)
Mainly saturated FAs in the rumen (stearic acid)
Why does sheep meat have a strong/offensive odor? What is the influence of their diet on it?
Because of the high amount of medium length branched-chain fatty acids (BCFAs).
Also it gets higher when in grain-fed than pasture-raised sheep.
