In this article we will discuss about:- 1. Preparation of Ghee 2. Chemical Composition of Ghee 3. Detection of Adulteration.
Preparation of Ghee:
Here some of the common methods which are applied in ghee making are mentioned:
1. Village Method:
In our villages, the ghee is made by curd or dahi. Dahi is churned in the mathni or village churn. It separates the curd into two parts. The first part is known as makkhan (a form of raw butter). It is a fat rich part of curd. The other part is known as mattha, (a form of buttermilk). The makkhan is removed from the mattha and heated to make ghee. It is normally heated in a metal pan (kadahz) over an open fire.
The yield of ghee by the village or indigenous method is about 82% of the milk fat in the original milk. Of that milk fat about 2.5% is lost in handling, about 2% goes into the ghee residue and about 13% is found in the buttermilk or mattha.
2. Butter Method:
For ghee making, butter must not contain any colouring matter or preservative or common salt. Butter is heated to remove its moisture by evaporation.
The equipment employed by the dairy processing plant for heating butter is usually a steam jacketed kettle, although a karahi may also be used when production is on a small scale. After heating, the contents of the kettle are allowed to stand undisturbed for a while before the ghee is removed from above the residue, as in the village method.
The yield of ghee by the butter method is about 92% of the milk fat in the original milk. Of that milk fat, losses are, about 0.8% in the buttermilk, 1.4 % in the ghee residue and 4.5 % in handling.
3. Cream Method:
When cream is used for making ghee directly by heating, the content of cream should be as high as possible. High fat content in such cream has two advantages.
First, the heat required to evaporate the free water present in cream decreases as its fat content increases. Secondly, high fat cream has a comparatively low milk solid (other than fat) content. Because of the fat globule surface complex, the concentration of fat in cream gives it qualities that require special care during certain process. For one thing, cream will loam readily and profusely during heating if special care is not taken to prevent it.
By-products of ghee making by separation and the direct heating of cream are skim and ghee residue. Of the fat in the, original milk, about 88% is reported to be recovered in the ghee, losses are 1.4% in the skimmed, 9.0% in the ghee residue and 1.7% in handling. The village and butter methods of ghee making can yield ghee of better colour and flavour than the cream method.
4. Pre-Stratification Method:
Making ghee from butter by using the induced or pre-stratification procedure, a special ghee kettle is required. This kettle is equipped with a bottom opening and valve by which it is possible to remove the bottom layer of the pan contents without disturbing the upper layers.
The first stage of heating involves raising the butter temperature to 80°C, it is then held for about 30 min. Three layers or strata of the product form.
On the top is a thin layer of curd particles which is not removed before the completion of the heating because the curd which it contains produces the characteristic ghee aroma when heated with the fat at 100°C and above heating continue by the completion of the first stage, followed by the second and third stages, as outlined above. Ghee shall contain no more than 0.3% moisture, the remainder is almost entirely pure milk fat.
The more completely the moisture is removed during final heating, the greater is the phospholipid content of the ghee. One hundred grams of ghee provide nearly 896 kcal of energy. In addition, it is an extremely rich source of essential fatty acids.
Chemical Composition of Ghee:
The chemical composition of ghee is given in here in a tabular form. Here, we can also know the contents in ghee made from the cow and buffalo milk.
Normally, the fat% is more in the case of buffalo milk than in the cow milk.
Detection of Adulteration in Ghee:
To acquaint with the problem of adulteration in ghee and their detection the test may be used.
The following tests may be used for the detection of adulterants in ghee sample:
1. Test for Vegetable Fat:
To acquaint with the problem of adulteration in ghee and their detection the test may be used.
The following tests help to detect the presence of vegetable fat or the hydrogenated fat in ghee:
(i) Bomner’s Phyto-Sterol-Test:
50 g of ghee is weighted and saponified with 100mL of alcoholic potassium hydroxide and 300 mL of distilled water is added. This solution is passed through ether to dissolve unsaponified cholestrine and phytosterine. Ether is evaporated and residue (Unsaponified matter) is treated with 2 mL acetic anhydride for 15 min and is filtered.
When crystals of acetate are formed, filtrate is evaporated. These acetate crystals are dissolved in alcohol and recrystallised. If melting point of these determined is above 17°C, it indicates the presence of phystosterol acetate which means presence of vegetable fat or oil.
(ii) Valenta Test:
Take 3 mL of ghee and 3 mL of glacial acetic acid and warm the content in a test tube. Agitate it frequently and note the melting point. If it is above 39°C, it indicates presence of animal fat, but if abnormally low (i.e., below 29°C), then there is presence of coconut oil.
(iii) Baudouin Test:
Melted sample of ghee is shaken with cane sugar solution in hydrochloric acid. If sesame oil is present in ghee, it shows red colour.
(iv) Halphens Test:
Take 5 mL of amyl alcohol and add 1 mL of 1% of sulphur solution in carbon disulphide and mix with 10 mL of sample ghee. This is heated at 125°C for one hour. If red colour appears, it indicates the presence of cotton seed oil in ghee.
(v) Nitric Acid Test:
A sample of 3 mL of ghee is melted in a tube and 3 drops of concentrated colourless nitric acid is added and kept in hot water bath.
Observations are made as given here:
(vi) Soda Ash Test:
Ghee sample is melted and equal amount of 25% sodium carbonate solution is added. It is shaked well and kept in boiling water for few minutes. Turbid liquid is formed. When it is kept for few more minutes, two layers formed are on standing.
2. Test for Animal Fat:
Ghee adulterated by animal fat can be detected by the tests given here:
i. Valenta test
ii. Nitric Acid test
iii. Carbolic Acid test