Module 7. Butter-making process

Lesson 20

20.1 Introduction

Economy of butter manufacture greatly depends on the recovery of milk fat into butter, which in turn is decided by the amount of fat lost into buttermilk. There are several factors which determine the extent of fat losses in buttermilk. Use of break water is an important one among them. The primary purpose of adding break water and washing the butter is to reduce the amount of residual buttermilk in butter. When butter grains are formed, break water is added before draining the buttermilk. Break water helps in controlling the temperature of the butter churns and thereby the product’s consistency.

20.2 Addition of Break Water

Breaking refers to the stage where cream (oil-in-water emulsion) is converted to butter (water-in-oil emulsion). The butter grains formed are of pin head size and they tend to stick together to form large butter clumps. This may result in incorporation of buttermilk in these clumps which may not be washed later in the washing stage. To prevent this clumping of butter grains, break water is added just after phase reversal and draining of butter milk. The temperature of break water is slightly below the temperature of buttermilk drained.

20.3 Washing of Butter

Washing of butter means removal of remnants of curd adhered to surface of butter grains. After draining the butter milk, drain plug is closed and churn is filled with water (1-2°C below churning temperature) to same level as when filled with cream. The churn is then run at slow speed for 12-15 revolution and wash water drained.

The purpose of washing butter grains is:

i) To wash away free butter milk from the butter granules so as to reduce the curd content of butter and thus to improve keeping quality.

ii) To control the temperature of granules so as to facilitate the subsequent working operation and to control the firmness of resultant butter.

iii) To wash off undesirable flavouring compound, thus it has dual effect:

a) If cream is of poor quality, washing may improve flavour and even double washing may be practiced.

b) If cream is of good quality, washing may flatten the flavour and therefore washing may be eliminated.

The curd content of unwashed butter varies from 1.1 to 1.5% and that of washed butter from 0.6 to 1.0%. If butter is made from good quality, well pasteurized sweet cream washing may be eliminated otherwise washing is important for production of sound butter of good keeping quality.

20.3.1 Temperature of wash water

The temperature of wash water has a noticeable effect on the firmness and texture of butter. Under normal conditions and with butter granules of desired firmness, it is general practice to keep the temperature of wash water few degrees below the temperature of buttermilk (or equal to the temperature of cream in the churn). Since lower temperature harden and higher temperature soften the butter, it has been the general practice to keep lower wash water temperatures in summer (when the butter tends to be excessively soft) and to use higher wash water in winter where the natural tendency is for the butter to be excessively hard and crumbly.

20.3.2 Thoroughness of washing

The proportion of the buttermilk constituents contained in butter such as curd, acid and ash that can be removed by washing is limited to the buttermilk that adheres to the surface of the butter granules and that is entrained between the granules. But the buttermilk contained in the interior of the granules is so finely dispersed within the granules that it is not removed by wash water. It is for this reason that the washing of butter does not remove curd completely from butter. It is suggested that approximately 25% of the curd contained in unwashed butter is removed after washing.

20.3.3 Relevance of washing in unsalted butter

Washing is done to maximize keeping quality of butter but excessive washing may not always do so. Under certain conditions, it may tend toward accelerating deterioration. This is particularly noticed in unsalted butter made from properly ripened cream. When such butter is excessively washed, much of the pronounced flavour character passes into the wash water and is lost to the butter. The preservative characteristics developed in ripening (lactic acid, lactates etc.) are washed away by wash water and resistance to bacterial deterioration is diminished. Such butter usually have washed out or flat flavour defects and soon develop a stale flavour followed by cheesy flavour. On the other hand, unsalted butter when optimally washed resists bacterial deterioration better and fresh flavour is retained longer.

20.3.4 Quality of wash water

Wash water should be free from taints or smell and dissolved Fe and Cu ions. It should be bacteriologically sterile. Satisfactory chilled water may be sterilized by addition of chlorine sanitizer to give 2 ppm available chlorine content.

20.3.5 Initial working

After draining of wash-water there is just sufficient water left in the churn to give (when worked into butter) initial moisture content of about 13-15%. It is an important stage judged by the operator by observing the flow of wash water.

If moisture content is likely to become more after draining of wash water, the churn should be closed and revolved for several minute until granules join together to form large lump. The churn is then stopped and free water drained.

20.4 Factors Influencing the Fat Losses in Butter Milk

20.4.1 Season

Fat losses in buttermilk are higher in summer than in winter. Lowering the cooling temperature of the cream sufficiently to compensate for the softer summer fat assists in preventing fat loss in buttermilk.

20.4.2 Fat content of cream at churning

Higher the percentage fat of cream, higher will be the percent fat in buttermilk but the percentage loss of fat will be lesser. The percentage of fat in butter milk will be high if the percent fat in cream is high. Cream of medium richness gives low fat loss.

20.4.3 Size of fat globules

The greater the proportion of small sized fat globules (2 microns or less), the greater will be the fat loss and vice versa. Small fat globules have more surface area and thus there are more protective substances on small fat globules. Due to these protective substances, small fat globules escape churning action and pass on to the butter milk and thus results in more fat loss.

20.4.4 Acidity of cream at churning

Higher the acidity of cream, more will be the fat loss in buttermilk if the high acidic cream is pasteurized. Heat treatment of high acidic cream results in precipitation of protein which also entraps some fat globules. This precipitate is lost in butter milk along with the entrapped fat globules.

20.4.4 Neutralization

Cream should be neutralized properly before pasteurization to prevent excessive fat loss in buttermilk. Excess acidity should be neutralized before pasteurization otherwise protein may get precipitated incorporating fat with it and thus lead to more fat loss in buttermilk.

20.4.5 Cooling temperature of cream

The temperature to which cream is cooled and churned and the time for which cream is held before churning are important fundamental factors that control the fat loss in buttermilk. When butter comes abnormally fast and is soft, fat in buttermilk is invariable high. This is usually due to insufficient cooling of the cream and/or not holding it long enough at the cooling temperature.

20.4.7 Physical properties of butter fat

Physical properties of butter fat particularly the ratio of high and low melting point triglycerides are affected by a number of factors like season, stage of lactation, feed and many more. Higher the proportion of low melting point triglycerides more will be the fat loss in butter milk.

20.4.8 Load of churn

Overloading of churn affects the exhaustiveness of churning and thus incomplete churning leads to higher fat loss in buttermilk. It also prolongs the churning time. Churning time can be controlled by increasing temperature but then, the increased temperature result in more fat loss.

20.4.9 Common causes of loss of an excessive amount of the fat in the butter milk

1. Low testing or excessively high testing cream.

2. Diluting the cream with water or with an excessive amount of starter.

3. Improper neutralization and pasteurization.

4. Slow cooling and excessive agitation during cooling or forgetting to stop the coil when cooling is finished.

5. Partial churning during pumping.

6. Churning too soon after pasteurization and cooling especially during spring and summer.

7. Not holding cooled cream at low enough temperature after pasteurization

8. Churning at too high temperature.

9. Washing the cream excessively during churning.

10. Excessive speed of the churn.

11. Over loading the churn.

Last modified: Friday, 5 October 2012, 9:38 AM