- 1 FATS AND OILS SEMESTER-II NOTES
- 2 Classification (based on the origin and degree of saturation)
- 3 Autoxidation (factors and prevention measures)
- 4 Flavour reversion
- 5 Refining, Hydrogenation & Winterization
- 6 EFFECT OF HEATING ON FATS & OILS WITH RESPECT TO SMOKE POINT
- 7 EFFECTS OF HEATING ON SMOKE POINTS OF FATS & OILS
- 8 Commercial uses of fats (with emphasis on shortening value of different fats)
- 9 COMMERCIAL USES OF FATS
- 10 FACTORS THAT AFFECT THE SHORTENING POWER OF FATS
FATS AND OILS SEMESTER-II NOTES
Lipids are organic compounds which are only soluble in organic solvents and are greasy in nature.
Tri-glycerides are esters.
Tri-Glycerides are lipids made out of 3 parts of fatty acids and 1 part of glycerol.
FATS & OILS
Fats and oils are mixed tri-glycerides, flavor compounds and some other substances.
DIFFERENCE BETWEEN FATS AND OILS
1.Fats are solid at room temperature and oils are liquid except coconut oil.
2.Fats and oils are made up of saturated and unsaturated fatty acids. Oils contain more of unsaturated.
3.Fats have single bond and oils have double or triple bond.
4.Fats have higher melting points than oils.
5.Fats are mostly animal based and oils are mostly plant based.
FAT AND FATTY ACIDS
Butyric Acid –Butter
Classification (based on the origin and degree of saturation)
CLASSIFICATION OF FATS & OILS
A.BASED ON THE ORIGIN
PLANT BASED FATS & OILS
Seeds-Mustard Oil, Sesame Seed Oil,Canola Oil,Flaxseed Oil,Cotton seed Oil
Flowers-Sunflower Oil, Safflower Oil,
Fruits- Olive oil, Palm oil,Coconut Oil
Nuts-Almond Oil,Peanut Oil
ANIMAL BASED FATS
Lard,Suet,Tallow,Butter,Ghee,Fish Oil,Cod Liver Oil
Dalda,Vegetable Fat,Margarines,Hydrogenated Fats
Autoxidation (factors and prevention measures)
Refining, Hydrogenation & Winterization
Hydrogenation can be defined as the process of addition of hydrogen under controlled conditions into vegetable oils in the presence of nickel as catalyst such that the vegetable oil is converted into fat.
This process was introduced to lower the prices of fat for commercial use.
If the oil is subjected to refrigeration it becomes cloudy since, the fats and oils are composed of both saturated fatty acids and unsaturated fatty acids, the saturated fatty acids becomes solid at lower temperatures and the process is called winterization.
Winterization is the process that is used to make salad oil.As the name suggest,salad oil is used for dressing salads.salads are served cold ,therefore winterized oil ,the oil from which solid fats are removed will be the best quality,to serve the purpose.There won’t be the solidified oil on salad anymore.
EFFECT OF HEATING ON FATS & OILS WITH RESPECT TO SMOKE POINT
SMOKE POINT is the standard for choosing the oil and fats according to the purpose and temperature of cooking with them.
FLASH POINT,FIRE POINT & SMOKE POINT
It is the lowest temperature for an oil to evaporate enough to form a combustible concentration of gas.
It is the lowest temperature for an oil whereby the vapour of the oil continues to burn for at least 5 seconds after ignition by an open flame.
It is the temperature at which an oil begins to produce a continuous visible bluish smoke.
SMOKE POINT defines whether an oil or fat is fit for high temperature cooking like frying.
EFFECTS OF HEATING ON SMOKE POINTS OF FATS & OILS
1.When fats and oils are heated past its smoke point they start to break down with the release of free radicals and a substance called acrolein.Acrolein gives the burnt food their acrid flavor and aroma.
2.As the oil is heated more free fatty acids are made which lowers the smoke point gradually leading to degradation of the oil.
3.It increases the chances of auto-oxidation.
4.The oil becomes rancid more easily.
Commercial uses of fats (with emphasis on shortening value of different fats)
The role of different types of fats and oils in cookery depends upon
- On their composition and
- properties For example,
Liquid fats or oils with a high smoke point are used for deep fat frying purposes.
Solid fats like butter and margarine are used as shortening and tenderizing agents in foods.
A shortening is defined as a fat, solid at room temperature, which can be used to give foods a crumbly and crisp texture such as pastry. Examples of fat used as “shorteners” include butter, margarine, vegetable oils and lard.
COMMERCIAL USES OF FATS
1.Medium of cooking.
2.As a shortening agent .
3.To add richness and flavor
4.To increase tenderness and make the product short.
5.To Form emulsions.
6.As a spread and be plastic.
MEDIUM OF COOKING
Fats and oils have a high boiling point as compared to water. Therefore foods get cooked in fat in shorter time than when cooked in water. Fried foods such as wafers and chivda, have a crisp texture and a delicate flavor. The high temperature used in frying destroys harmful bacteria, thus making the food safe for consumption. Some fat is absorbed by the food and the calorific value of the food is increased when it is cooked in fat or oil.
In many preparations, such as cakes, biscuits, kachauri, and namkeen, chakali, shakkarpara, biscuits, pastry etc. fats or oils are added to improve the texture. The fat covers the surface of the flour particles and prevents the sticking of particles together. Many factors such as the nature of the fat or oil, the amount added, the temperature, presence of other ingredients, manipulation and the extent of mixing, affect the shortening power.
AS A SEASONING
Fats and oils are used to season most food preparations. In sweet preparations, fats, such as butter, ghee, vanaspati
TO ADD RICHNESS AND FLAVOR
It adds flavor and richness in various food products as in halwas,toppings,cakes,pasteries etc.
TO INCREASE TENDERNESS AND MAKE THE PRODUCT SHORT
To add crispiness to biscuits,chips,namkeen,farzans etc.
TO FORM EMULSIONS
In various sauces,coulis etc.
AS A SPREAD AND BE PLASTIC
In bread and butter,greasing,sandwiches ,compound butters etc.
FACTORS THAT AFFECT THE SHORTENING POWER OF FATS
THE NATURE OF THE FAT
Fats with the greater unsaturation (3 or more double bonds) have the greatest shortening power. Greatest shortening power means the greatest surface area of flour covered in a particular product.
As the concentration of Fat increases, its shortening power is also increased e.g. butter has less shortening as compared to hydrogenated Fats.
Fats are less plastic and oils are more viscous at low temperatures. Therefore, they spread led readily and are covered is smaller with the same amounts of mixing than at higher temperature.
PRESENCE OF OTHER INGREDIENTS
It modifies the shortening power of Fat. When oil or melted Fat is used in a batter with egg yolk, the Fat is emulsified as an O/W emulsion and has less shortening power.
MANIPULATION OF FATS
It includes creaming or stirring the Fat to soften it, thoroughly mixing Fat with flour, a way of handling and rolling and this affects shortening power.