Preparation of cream and cheese

                                                                             

 

                                                                                                                                                                                                              PREPARATION OF CREAM

• Hand skimming,  Milk is put in bowls and allowed to settle for 12 to 24 hours. During that period cream collects on top and is skimmed off. When this settling process is going on, the milk must be kept in cool places, say in a refrigerator to prevent it from getting sour. The main advantage of this method is that there is no expensive equipment required. However, efficient separation of cream from milk is not possible and as the process takes a long time, there is a danger of the milk becoming sour while waiting for the cream to collect on top.

    

• Mechanical separation of cream,  Milk is poured out in a mechanical device for making the cream. It passes in a continuous flow-through plate revolving at about  5000 revolutions per minute. The rising of fat globules to the top is assisted by centrifugal force. As the heavier skimmed milk (milk without fat)  is thrown to the outer edges of the plates, the lighter fat globules accumulate near the center from where they can be collected as cream. This method is quick. It eliminates the risk of milk getting sour and results in efficient separation of fat from milk. However, the machine used is fairly expensive.                                                                                                                                                                                                                                     PREPARATION OF CHEESE                                                                                               Cheese can be made from whole milk, skimmed  milk or cream. The main stages in cheese manufacture are four, namely, curdling the milk, removal of moisture from the curd, salting and ripening.                                                                                                                                                                                                                                                                                             
• Curdling the milk, Curdling is the process in which milk protein, casein, is coagulated to hard consistency. To assist this process, a starter( which is a culture of the lactic acid bacteria), is added to fresh milk. Usually, streptococcus lactis and streptococcus cremoris are used. An enzyme, rennin, is also added to encourage coagulation of the casein. Both the acid produced by the bacteria and rennin are responsible for the curdling of milk.                                                     When the curd has been precipitated; it leaves behind a watery fluid called  whey. The largest percentage of this fluid (nearly 93 percent) is made up of water but there is little lactose, proteins, fats, and minerals in it.                                                                                                                                           
• Removal of moisture from the curd,  After curdling, whey is drained off by putting the curdled milk in moulds which have small holes. However, there still remains some when in the curd at this stage. This can be removed by scalding( using boiling water). The process involves raising the temperature very gradually (by 0.56 centigrade per cent) is made up of water but there is a little lactose, proteins, fats and minerals in it.                                                                                                                                                                                            
• Salting,  Ordinary table salt( NaCl) is added to the drained curd or on the surface of the curd after cutting. In addition to imparting a good flavor and taste, salt increases the keeping quality of cheese by withdrawing water from cheese. It also prevents prevalence of micro-organisms which can cause decay.                                                                                                                                                                                                                                                
• Ripening, Apart from cottage and cream cheese which are soft and  unripened, most cheese requires ripening. During the ripening period, specific micro-organisms work on lactose, protein and fat to liberate certain desirable acids, alcohols and other compounds which contribute to the desired flavour and aroma.