The concept of fatty acids

The basic structure of fatty acids is a hydrocarbon chain, the basic formula: the number of n in CH3[CH2]nCOOH, is 2 ~ 24, basically even carbon atoms.

Type: saturated fatty acids（SFA）, unsaturated fatty acids(UFA)

There are about 40 different fatty acids in nature, classified according to the saturation degree, and can be divided into saturated fatty acids（SFA） and unsaturated fatty acids(UFA).

SFA

Saturated fatty acids（SFA） are represented by stearic acid (18:0), common in livestock and poultry meat, eggs, milk, palm oil, coconut oil, etc., the main role is to provide energy for the human body.Saturated fatty acids were previously thought to increase the concentration of "LDL cholesterol" in the blood and can easily lead to cardiovascular disease, but this discussion is gradually being challenged.In animal foods, saturated fatty acids are rich in saturated fatty acids, which are solid at room temperature, such as butter, lard, milk, mostly composed of saturated fatty acids.To put it more, the oil that is solidified "automatically without being put in the refrigerator" is mainly saturated fatty acids.

UFA

Unsaturated fatty acids are classified into monounsaturated fatty acid(MUFA) and polyunsaturated fatty acid(PUFA) according to the number of ω carbon bonds in the chemical structure; they can be further classified into ω-3, ω-6, ω-7 and ω-9 lines UFA based on the position of the ω carbon atoms closest to the end of the methyl group.The spatial structure of carboxylic acids is also divided into cis fatty acids and trans fatty acids(TFA).

MUFA

Monounsaturated fatty acid monounsaturated fatty acid chemical structure contains a carbon double bond, represented by oleic acid (18:1), can reduce the "Low-density lipoprotein cholesterol" concentration in the blood, and may improve the "High-density lipoprotein cholesterol" concentration, has the antioxidant function, can resist the damage caused by oxidation.Edible oil with high content of unsaturated fatty acids is liquid at room temperature.The main sources are vegetable oil, such as: bitter camellia oil, olive oil, mustard flower oil, etc., its unit of unsaturated fatty acids content is quite high.Pear and nuts (such as hazelnut, almond, cashew nut, etc.) are also quite rich in monounsaturated fatty acids, and animal lard, butter and chicken oil, its monounsaturated fatty acids content is not low, containing about 35 ~ 40%.

Unsaturated fatty acids are more unstable, less heat resistant, and liquid at room temperature.A high probability of toxicity when cooking at high temperatures.

PUFA

Polyunsaturated fatty acid chemical structure contains more than two carbon double bonds, poor stability, the more the number of carbon double bonds, the less the high temperature resistance.They are represented by linoleic acid (18:2), linolenic acid (18:3), arachidonic acid, etc. (20:4).Edible oils with many polyunsaturated fatty acids are liquid at room temperature and refrigeration.Polyunsaturated fatty acids are less stable and are not suitable for heating, cooking, or frying.The main sources rich in multiple unsaturated fatty acids of edible oil are soybean oil, peanut oil, sesame oil, flax kernel oil, deep-sea fish oil or shrimp oil.