Desirable characteristics, AGMARK standards and increasing shelflife of ghee

Desirable characteristics of Ghee

Ghee is characterized by a pleasant, nutty flavour and a creamy white to light yellow colour. It should be free from foreign colouring matter, sediment and should have a granular texture. It should be free from any objectionable odours.

The AGMARK standards of ghee are as follows.

Increasing the shelf life of ghee

When ghee is stored under ambient temperature, it undergoes oxidative deterioration. The oxidation of unsaturated fatty acids produces hydroperoxides and their subsequent breakdown products viz. aldehydes, ketones, low molecular weight acids and oxy acids. These components are responsible for the development of off flavours in ghee.

The Food Adulteration rules as amended in 1976 permit the addition of 0.02% by weight of butylated hydroxy anisole (BHA) and butylated hydroxy toluene (BHT) either singly or in combination in to the ghee. The problem in using the antioxidants continuously results in teratogenic or carcinogenic effect in small animals and primates.

In ancient days, betel leaves and curry leaves were usually added to the butter during the clarification process. But it is now recognized that these substances indeed possess antioxidant properties, which will not only improve the shelf life and taste of the product but also they are safe to the consumers.

A research was carried out to study the antioxidant property of betel and curry leaves at different concentration when they are boiled during the clarification process of ghee making. The findings show that the initial peroxide value of ghee (0.00) showed no increase up to 30 days of storage at 30°C. But the control samples showed a steep increase in peroxide value after 60 days of storage. Ghee samples treated with 1% curry leaves were found to be most resistant up to 135 days. The betel leaves at 1% concentration appeared to be most acceptable and stable even after 147 days of storage at 30°C.

The degree of hydrolysis of ghee during the storage is measured by titration for free fatty acid (oleic acid). After a month storage, there is a progressive increase in free fatty acid content. The control sample of ghee (not treated with any anti oxidant) showed a 100 percent increase in free fatty acid content (after 30 days) where as the betel leaves treated ghee (at 1% level) offered maximum protection to the ghee from hydrolysis.

It is observed that the plant leaves (curry and betel leaves) contain phenolic compounds such as hydroxychavicol, eugenol, and certain amino acids such as aspargine, glycine, serine, aspartic acid, glutamic acid, threonine, alanine, proline, and tryptophan which might possess antioxidant properties and help to improve the shelf life of ghee.

A slight reduction in the iodine value from 35.9 in control to 35.6 in treated ghee samples is observed when the samples are stored at 30°C for 147 days. Ghee samples treated with chemical antioxidants showed similar results. Ghee samples produced with curry and betel leaves showed a lowered butyrorefractometer (BR) reading. The compounds that go in to solution during the clarification process might be responsible for the lowered BR reading.

To conclude, the betel and curry leaves can serve as a potent antioxidant at 1% concentration without any adverse effect on the organoleptic properties of the ghee and help replace the BHA and BHT to extend the shelf life of ghee.

Tests to detect adulteration in ghee

1. Butyrorefractometer reading

Properly filtered ghee whose temperature is around 40°C is taken; 2-3 drops of it are poured in to the butyrorefractometer by the side of the glass rod. Now the reading is noted by the scale placed above the meter. Care has to be exercised to maintain the temperature of water that is flowing over the thermometer to be at 40°C. If the temperature deviates, then the results obtained may not be accurate.

2. Baudoin Test (Detection of adulteration of ghee with vanaspathi)

As per the prevention of food adulteration act, it has been made mandatory to add 5% sesame oil to vanaspathi in order to detect the presence of vanaspathi in ghee through Baudoin test. The principle behind the test is development of permanent crimson red colour with furfural in the presence of concentrated hydrochloric acid in ghee adulterated with vanaspathi.

How to detect?

Take 5 g of molten filtered ghee in a test tube and add 5 ml of concentrated hydrochloric acid and 0.1 ml furfural solution in alcohol (2%) and mix the contents thoroughly and it is allowed to remain undisturbed for 10 min. Development of crimson red colour shows that the ghee is adulterated with vanaspathi.

3. Detection of mineral oil in ghee

About 2 g of ghee is saponified with 25 ml of 50% alcoholic potassium hydroxide for one hour. Then the saponified content is transferred to a beaker containing 100 ml of water. Development of turbidity indicates the adulteration of mineral oil in ghee.