Creamery Butter Method

This is the standard method adopted by organized dairies. In this method unsalted creamery butter or white butter or cooking butter is used a raw material for ghee making. A typical plant assembly for the creamery butter method comprises the following units. (1) a cream separator (2) butter churn (3) butter melting outfits (4) steam-jacketed, stainless steel ghee kettle with agitator and process controls (5) ghee filtration devices, such as disc filters or oil clarifier (6) storage tanks for cream, butter and ghee (7) pumps and pipelines interconnecting these facilities (8) crystallization tanks and (9) product filling and packaging lines.

First, the butter mass is melted at 60oC. The molten butter is pumped into the ghee boiler. Alternatively, solid butter may also be transferred manually to ghee kettle.The steam pressure is increased slowly to raise the temperature of butter to 90oC.This temperature remains constant as long as the moisture is being driven off. The scum, which collects on the top surface of the product may be removed from time to time with the help of a perforated ladle. The temperature gradually rises and the heating at the last stage is carefully controlled. The end-point shows the disappearance of effervescence, appearance of finer air bubbles on the surface of fat, and browning of the curd particles. At this stage, the typical ghee aroma is also produced. The final temperature of clarification is adjusted less than 110oC. Heating beyond this temperature will generate a marked ‘cooked’ flavour. The ghee is then pumped, via an oil filter or clarifier, into crystallization tank, which are cooled by re-circulating water at 60oC. The ghee is then packed in suitable containers.

 

Advantages

•  This method produces ghee of highly consistent quality.
•  Quantity of ghee residue is very less, hence less fat losses.
•  Less space is required for storage of cooking butter, the raw material for this method.
•  Energy requirement are lower than direct cream and indigenous methods.
•  Longer keeping quality than indigenous method

Disadvantages

 The flavour of ghee prepared by creamery butter method is criticized to be either flat/bland or cooked, particularly to the consumers who are habitual of using village ghee made by traditional method. The granulation in ghee is also poor as compared with the earlier discussed method.

 

iv. Pre-stratification Method

The ghee boiler in pre-stratification method is slightly modified. A faucet is provided at lower end (almost at side of bottom) of the boiler to remove most of the buttermilk (moisture and SNF). In this method, white butter is heated at a temperature of about 80oC and left undisturbed for about 30 minutes at this temperature. The melted butter stratifies into three layers, viz., a top layer of floating denatured curd particles, a centre layer of fat, and a bottom layer of buttermilk. This separation of butter into layers is called as pre-stratification. The bottom layer of buttermilk contains 60-70 per cent of milk solids-no-fat and also over 80 per cent of moisture originally present in the butter. The buttermilk is mechanically removed without disturbing the top and middle layers. Afterwards, the temperature of remaining two upper layers is raised to the usual clarifying temperature of about 110oC and ghee prepared as discussed above for creamery butter method.

 

Advantages

•  Economy in fuel consumption to an extent of 60 per cent as compared with direct clarification.
•  The acidity of ghee is less, which results into longer keeping quality.
•  Exposure to high temperature for lesser time.
•  The amount of residue formation is reduced.

 

Disadvantages

 It is essentially a batch method unsuitable for continuous production of ghee.
 The flavour of ghee is very mild or rather flat.

 

v. Continuous Method

The batch methods for making ghee discussed earlier are highly suitable for small and medium scale production of ghee. With the increase in demand and scope for export of ghee, some very large organized dairies prefer to adopt a continuous ghee making methods. Some of the problems associated with the current batch methods of ghee making are:

•  Unsuitable for large-scale production.
•  High-energy consumption.
•  Excessive strain and fatigue on the operators.
•  Product exposed to the environment.
•  Cleaning of equipment is done manually.

All the limitations of the conventional batch methods given above are obviated by continuous ghee making plants. These systems work on the basis of two principles,viz. (a) moisture evaporation from cream/butter using thin film scraped surface heat exchanger (TSSHE) and (b) de-emulsification of cream using high speed clarifixator and oil concentrator followed by moisture evaporation. The design, function and special feature of continuous ghee making units are discussed below:

TSSHE for continuous ghee making: The white or cooking butter from continuous butter melter is pumped in balance tank where it is kept agitated by means of agitator to maintain the homogeneity of molten butter. Then the butter is pumped to the TSSHE. The flow rate of molten butter is indicated by a rotameter and controlled with a value provided on the inlet line. The centrifugal action of the rotor blade make the molten butter spread uniformly in form of a film on the heating surface of the SSHE. Steam is admitted at regulated rate into the jacket of SSHE. The rate of evaporation of water from the butter film is very fast due to turbulence caused by the action of rotating blade. The speed of rotor blade is controlled by a motor drive. The vapour is removed through the outlet provided at the top of the SSHE and can be used for heating the butter in balance tank, thus economizing the steam consumption. The temperatures of molten butter and ghee are indicated by thermometers and adjusted by controlled steam supply with valves. Ghee is collected continuously in the ghee tank. The residue is separated from ghee by the oil clarifier. Residue free ghee is finally transferred to packaging line/tank.
 

Cream de-emulsification method: This method of continuous ghee making is based on the principle of de-emulsification of fat in cream from oil-in-water phase to water-in-oil phase. In this process milk is separated into cream of 40% fat using a centrifugal cream separator. This cream is converted into plastic cream of 80% fat in a clarifixator and then further concentrated in a concentrator, which work under centrifugal force. The de-emulsification of fat is done mechanically in the clarifixator and concentrator. Scraped surface heat exchanger is used to generate flavour and remove most of the moisture from fat concentrate. The traces of moisture left in ghee are removed in a vapour separator and the ghee residue removed by a oil clarifier. The flow diagram of the process is shown in  below.

Flow diagram of Ghee manufacture by Cream de-emulsification method