Deffcts in Cream and Their Control

The requirements of high quality table cream or manufacturing cream are the same as given here under.

i) Clean, sweet, pleasant flavour.

ii) Smooth, uniform and reasonably viscous body and texture.

iii) Low titratable acidity.

iv) Packaged in clean, leak-proof containers under hygienic conditions.

Defects in cream develop during storage. These defects may be due to poor initial quality of milk from which it is separated or faulty methods of production, processing,packaging and storage. As the storage period advances, the titratable acidity of cream also may increase. This may lead to defects like the curdling/serum separation.During storage, usually cream is prone to the development of flavour defects more rather than body and texture defects.

 

i. Flavour Defects and Control Measures

Common flavour defects likely to develop during storage are given here with their probable causes and control methods.

Acidic flavour may develop due to all or any of the following causative factors:

i) Use of sour milk for cream separation,

ii) Holding raw cream for longer period at ambient temperature,

iii) Using less than recommended time-temperature combination for pasteurization,

iv) Prolonged storage,

This requires strict maintenance of sanitary condition in the plant, reception of only good quality milk, using proper processing methods and storage temperature.

Cooked flavour: Uncontrolled excessive heating at any stage of processing of cream may lead development of cooked flavour. Hence, it requires check on pasteurization temperature in particular.

Oxidized/Oily/Metallic/Tallowy flavour: These kinds of flavour develop due to oxidation of fat caused by exposure of cream to light, metals, like copper/iron.Hence, its control requires proper packaging material and avoiding any metallic contamination during processing of cream.

Rancid or Bitter flavour: This is due to hydrolysis of fat by the action of enzyme lipase. Lipase may come from initial under heating and high microbial population.Entrance of moisture through packaging enhances the problem. Therefore, proper heat treatment, prevention of post processing contamination and proper packaging may serve as control measures. Bitter flavour may also come from milk if the animal is fed on some bitter weeds.

Cheesy flavour: The flavour of cream resembles that of cheddar cheese. Presence of proteolytic bacteria in cream leads to breakdown of protein causing this defect.Prolonged storage may allow psychrotrophic bacteria to grow at low temperatures and cause the defect. Prevention of post pasteurization contamination and quick disposal of the product may help reduce the problem.

Yeasty/Fruity flavour: Microbial contamination, use of improper processing methods,post processing contamination, unhygienic conditions prevailing in the plant lead to the development of undesirable flavour like that of vinegar, etc. It requires proper hygienic control at every stage of processing besides plant hygiene.

Utensils flavour: Use of dirty utensils imparts this objectionable flavour to cream.Therefore all the utensils and equipment should be properly cleaned and sterilized before and after use.

Feed/Weed flavour: This type of flavour defect comes from milk from the milch animals fed on some objectionable flavour imparting feed or weeds. Therefore strict control should be exercised while receiving the milk to control the defect.

 

ii. Body and Texture Defects

Curding: This defect is indicated by the appearance of flakes or coagulated particles in cream. This defect may result due to the following reasons:

i) Initial poor quality.

ii) Development of acidity.

iii) High temperature of storage.

iv) Post processing contamination.

Phase Separation: When this defect develops the watery portion and coagulated particles or lumps form two layers in the containers. It mostly happens due to thawing of frozen cream. It is, therefore, better to avoid frozen storage of cream to control the problem.

Undesirable fermentation: It may result in flavour as well as body & texture defect. This is mainly caused by the contamination of cream at any stage of processing particularly after pasteurization. It is, therefore, necessary to take all the precautionary measures to control contamination during and after processing including packaging to avoid the problem.