Keeping Quality of Ghee and Butter Oil

Ghee is expected to have the keeping quality of about 9 months on storage at about 21oC when packaged in rust free lacquered tin containers. The spoilage of ghee and butter oil results into:

•  Production of objection off-flavour, thereby loosing the consumers’ acceptability
•  Adversely affect its nutritive value on account of
• - Lestruction of fat-soluble vitamins and carotene
•  Formation of toxic products due to auto oxidation
•  Loss of attractive colour

i. Factors affecting keeping quality

It is highly essential to identify the factors that influence the keeping quality of ghee and butter oil so that they can be effectively controlled during production and storage. Some of these factors are listed as below.

•  Initial moisture content in ghee and butter oil
•  Initial acidity in the products
•  Amount of residue/sediment
•  Oxygen content in packaged products
•  Copper, iron and other catalytic salts
•  Method and type of packaging
•  Storage temperature
•  Exposure to light

Under practical situation the moisture content in ghee and butter oil is about 0.2%(the extreme limit can be 0.5%) when properly processed. The higher moisture content is responsible for faster hydrolysis of fat and other deteriorations. Similarly higher initial acidity, oxygen content and presence of catalytic salts, which accelerate the fat oxidation, always increase the rate of spoilage of anhydrous milk fat. The spoilage of these butterfat products is also directly proportional to the storage temperature and prolonged exposure to direct sunlight.

 

ii. Extension of keeping quality of ghee and butter oil

The following approaches can be used:

Use of good quality raw material: Raw material used for the manufacture of ghee and butter oil should be of good quality. Any off flavour, such as acidic,oxidized, and rancid present in raw material shall be carried over to the final product. The raw material should also be checked for the presence of copper and iron, which should not be more than permissible limits.Method of manufacture of ghee: Ghee prepared by desi method has higher moisture and higher acidity and thus lower keeping quality. If ghee is to be stored for longer time than this method should be avoided. The sulphydryl and phospholipid contents have antioxidant properties in ghee and butter oil. Those methods, which releases higher amounts of these natural antioxidant components should be adopted.Heating butterfat with higher amounts of solids-not-fat, as in case of direct cream method, at higher temperature of clarification will produce more sulphydryl and thus better shelf life. Probably due to this reason the keeping quality of ghee is more than butter oil.The pre-stratification method produces ghee with higher amounts of phospholipids because its loss in ghee residue is minimum. Also the extraction of phospholipids from ghee residue and addition @ 1 percent to the ghee enhance its keeping quality.

Addition of antioxidants: The antioxidants are added universally to anhydrous butterfat and high fat food products. There are two sources of antioxidants, namely synthetic and natural.

Synthetic antioxidants: These include

- Gallates (ethyl, propyl and octyl),
- Butylated hydroxy anisol (BHA)
- Butylated hydroxy toluene (BHT)
- Tertiary butyl hydro quinone (TBHQ), and many more.

PFA rules do not allow any synthetic antioxidant in ghee whereas permits the addition of gallates upto a level 0.01% and BHA & BHT upto 0.02% in butter oil
.
Naturally occurring antioxidants: There are many plants and herbs, which have antioxidant properties and may be added particularly to ghee for extending the keeping quality. Some of the examples of such natural sources are as below:

– The seeds of soybean and safflower are rich source of phospholipids. Their addition to ghee and butter oil at 0.5% level during boiling may delay the oxidative rancidity.

– Juices of Amla (Phyllanthus amblica) at level of 1.25% in ghee can retard the fat oxidation possibly due to high content of ascorbic acid and gallate in amla.

– It has been found that addition of betel and curry leaves (at rate of 1% of ghee) during heat clarification of butterfat improves not only the oxidative stability but also colour and flavour of ghee. The antioxidant properties of these plants are attributed to their phenolic compounds, predominately hydroxy charicol. The betel and curry leaves also contain carotene and ascorbic acid, which have tendency to undergo oxidation by consuming all free oxygen that may be present in the head space of the ghee container.

Packaging and storage conditions: Tin cans are best to protect ghee against oxidative spoilage. The reason being that hot filling of ghee is possible in tin cans, which will exclude most of the oxygen from the product and also enable to replace oxygen with nitrogen gas. The headspace in such containers can also be minimized. Ghee should not be exposed to direct sunlight or irradiation. It should preferably be stored at about 22oC.