Fats and taste

The main molecules we eat in our food are carbohydrates, proteins and fats. Fats are triglycerides, that is, compounds made of a central glycerol holding three chain polymers of fatty acids. The picture shows an unsaturated fat triglyceride (C55H98O6). The left part is glycerol while the right part contains, from top to bottom, the three acids, palmitic acid, oleic acid, and alpha-linolenic acid.
BOX on composition of triglycerides
For those of you who have studied some organic chemistry, the chain polymers in a triglyceride are of the form CH2-CH2-CH2-... and have 16 or more carbon atoms. In organic chemistry fats are classified as esters. These esters are derived from compounds called organic acids containing the characteristic -COOH group. The esters are formed from the acids by replacing one OH (hydroxyl) group in the acid group with another kind of molecule (an -O-alkyl or what is called alkoxy group). Esters are responsible for the aroma of many fruits such as bananas, applees, pineapples, etc. But esters are also famous in clothes as polyester garments.
END OF BOX

Types of Fat
The fatty acids can be saturated with hydrogen atoms, that is, they contain all the H atoms possible. An example is stearic acid. These acids tend to be harder and may be solid such as butter and ghee. Stearic acid is used in the production of detergents, soaps, shaving cream and other cosmetics.
Or they can be monounsaturated, missing one pair of H atoms, which is replaced by a carbon-carbon double bond. An example is oleic acid. As you can guess from the name, it is present in many oils, such as peanut oil or sunflower oil.
Or fatty acids can be polyunsaturated, missing many pairs of H atoms, which are replaced by double bonds. These acids tend to be softer and may be liquid. An example is linoleic acid (LA), found in many nuts, seeds and their oils, such as safflower, sunflower, corn (maize), sesame. It is used in the manufacture of oil paints.
Another example is alpha-linolenic acid (ALA), also found in many seeds and their oils, for example chia seeds (from central America), kiwi seeds (from China and New Zealand), and flax seeds (from central Asia). One of these two fatty acids is essential for human nutrition.

Butter and ghee
A fat can be a combination of these: for example, one of its fatty acids can be saturated, one can be monounsaturated, one can be polyunsaturated. Oils (which are liquid fats), nuts and chocolates typically have a combination of these kinds of acids. The word ``oils'' is sometimes used for unsaturated fatty acids. Butter is a mixture of milk fat, water and protein solids. Milk fat is a mixture of saturated and monounsaturated fats. The word ``lipid'' is used for fats and other chemicals like cholesterol, which is a fatty alcohol.
In India we clarify butter to make {ghee}: the butter is melted and the water is boiled off. The process also burns off proteins and milk sugars, so ghee can be taken by people who cannot take lactose products. What is left behind is highly saturated milk fat, delicious---but it also thickens the arteries in our bodies.
Do noodles have fat? Yes, they do, nearly 20 per cent is fat. This is acquired when the noodle is prepared, which involves deep frying. Although the Chinese claim priority over noodles, pasta, thukpa, vermicelli, idiyappam have been known in different cultures since as far back as we know.

Taste of food
While we are on the subject, what is monosodium glutamate (MSG) or ajinomoto, which are famous for giving noodles their umami taste? As its name indicates, it is a salt of glutamic acid, which is one of the amino acids found in proteins. Seaweed are rich in free glutamates and the Japanese have used them for a long time in their soups. But free glutamates are also found in cheese, tomatoes, mushrooms. You can see that these foods have good flavouring! Human beings clearly have a taste for umami (you do like sauces and ketchups, don't you?). They have receptors to recognize its "savouriness" on their tongues just like they have for the sweet, sour, bitter and salty tastes. Scientists have suggested that this taste may have encouraged people to eat peptides and proteins, which are essential for the body.
In India and China, ``hotness'' as in chillies, black pepper, ginger and horseradish, or the ``coolness'' of menthol, are thought of as tastes. These are sensations which go under the name of chemesthesis. They are not tastes, there are no receptors on the tongue. These foods are ``irritants'', they directly excite nerve fibres. The same thing leads to tears in one's eyes on cutting onions, or the ``stinging'' in the throat with some carbonated soft drinks.
In 2015, Richard Mattes and his colleagues at Purdue University suggested that oleogustus (``oily'' and ``fatty'') is another taste, found for example in cheese which stinks or meat which has turned rancid. Their suggestion was that like bitterness, human beings developed this taste as a warning mechanism for bad food. But this has not been widely accepted yet.
Adapted from 
What Einstein told his cook
by
Robert Wolke