- Technical Blog From My Notebook

Monday, February 17, 2020

Butter making in batch churn-Dairy Engineering-Technical Superintendent Milk Marketing Federation ltd

Butter making in batch churn-Dairy Engineering-Technical Superintendent Milk Marketing  Federation Ltd

There are four basic stages involved in any butter making process. These include: 

1. Concentration of the fat phase of milk by separation of milk.

 2. Crystallization of the fat phase of milk by cooling and ageing.

 3. Destabilization of the oil-in-water (o/w) emulsion. 

4. Formation of a plasticized (water-in-oil) w/o emulsion.

Butter making in batch churn Though batch churns are still in use, they are rapidly being replaced by continuous butter making machines (CBMM). 

The steps involved in butter making by the batch method are as follows: 

I. Preparation of cream

 The steps involved in the preparation of cream for butter making are standardization of cream (38-41 % fat), pasteurization (80o C/16 sec.), cooling (~ 5o C) and aging (5-8o C/6-12 h) of cream.

 Standardization of cream fat will help to obtain ‘exhaustive churning’ i.e. churning in the normal time period (~ 45-60 min for a batch) with minimal fat loss in buttermilk. 

Ageing of the cream helps in improved partial solidification of fat that helps in imparting good body and texture to butter and minimizes fat loss in buttermilk. 

II. Churning of cream and draining of buttermilk 

The cream is churned after slight raising the temperature of cream (i.e. 9-11o C) from the ageing temperature; the cultured cream may be churned to obtain ‘Cultured butter/Ripened cream butter’. 

Butter was traditionally made in cylindrical, conical, cubical or tetrahedral churns with adjustable speed.

 Axial strips and dashers are fitted inside the churn.

 In batch churns, the mechanical stress is created by rotating the partly filled churn so that the cream is lifted up the ascending wall of the churn and then cascades to the base. 

In such churns, aeration and foam formation and collapse are relatively important, in a process taking 40-60 min. 

In the churning process, the cream is agitated violently to breakdown the fat globules, causing the fat to coalesce into butter grains. 

The churn is usually filled to 40-50% of its capacity, to allow space for foaming.

 Modern churns have a speed range that permits selection of the most suitable working speed for any set of butter parameters. 

Upon churning, the cream is split into two fractions: butter grains and buttermilk. 

The machine is stopped when the grains have reached a certain size (peanut), and then the buttermilk is collected separately in buttermilk silo.

The size of churns has increased greatly in recent years. Churns of 8,000-12,000 lit./batch capacity or more are used in large creameries.

 III. Washing of butter grains 

It is a common practice to wash the butter with pasteurized chilled water to remove any residual buttermilk and milk solids; this helps in reducing the curd (i.e. SNF) content (limit of 1.5% as per FSSA) of butter. 

IV. Salting of butter 

Salting of butter helps in enhancing the flavour and also extends the shelf life of butter. 

The salt should be chemically pure, extra-fine (pulverized) and quickly and completely soluble. 

Salt is normally added dry but can be added in the form of brine too. 

Recommended percentage is limited to 2 % for long-life butter. 

Too much salt can lead to the presence of free moisture in the finished product and make the product prone to flavour defects, if stored for a long time. 

V. Working of butter 

In order to subject the butter to the working process, the batch butter churns are equipped with either working vanes or working rollers. 

The churn is allowed to revolve at a speed much lower than that of churning for a specific period of time (20 – 35 min) in order to ‘work’ the butter. 

The butter grains are pressed and squeezed to remove the moisture between them.

 The fat globules are subjected to a high pressure and liquid fat and fat crystals are forced out. 

In the resulting mass of fat (eventually the continuous phase), the moisture becomes finely dispersed by the working process, which is continued until the required moisture content (maximum 16 %) is obtained. 

In most churns, there is a provision for vacuum working so that butter contains less air (< 1%) and is more dense and compact. 

If butter is to be salted, salt is spread over the surface of pre-worked butter in batch production.

 After salting, the butter must be worked further to ensure uniform distribution of the salt.

Proper working results in uniform dispersion of aqueous phase droplets in the continuous fat phase coupled with their microscopic size, restricts microbial growth due to the limited nutrient availability.

 VI. Unloading of butter 

Butter from the batch churn may be dropped onto previously clean and sterilized butter trolleys, wheeled to the packer, and then either tipped or shoveled into the feed hopper. 

VII. Packaging of butter 

The butter is then portioned, via a continuous packaging machine, into vegetable parchment paper which is then enclosed in a card board box. 

The sizes packed maybe 10 g chiplet, 100 g block, 500 g block and even 400 g tinned butter; later one is exclusively packed for armed forces. 

White butter may be packaged in bulk in cardboard box lined inside with polyethylene in 15 kg packs. 

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