Cream is the fat rich product of milk obtained by gravity or mechanical separation. It is the light weight portion of milk which still contains all the main constituents of milk, but in different proportions.

Fat content of cream varies widely from 18 to 85 % depending upon the method of separation. Tar/Malai is cream obtained by hand skimming of heated and cooled milk.

​

Classification

The fat in cream may vary from 18 – 85%; the SNF constituents in lower proportions than in milk. Cream may be broadly classified as:

• Market cream: Used for direct consumption, and
• Manufacturing cream: Used for the manufacture of dairy products

CREAM, CLASSIFICATION AND WHIPPING CREAM

• According to Food Standards Safety Act (2006), cream including sterilized cream means the product of cow or buffalo milk or a combination thereof. It may be of following 3 categories:
•  Low fat cream: containing milk fat not less than 25% by weight
• Medium fat cream: containing milk fat not less than 40% by weight
• High fat cream: containing milk fat not less than 60% by weight
• Cream sold without any indication about fat% are “high fat cream”
• Malai means the fat rich product prepared by boiling and cooling cow or buffalo milk or a combination thereof, containing not less than 25% fat

• WHO (1977) have suggested the following standards for market cream:

According to FAO standards, the following classification is made according to the fat content:

Coffee Cream

• Coffee cream is a shelf-stable product with >10% fat. It is homogenized and UHT processed, filled aseptically or sterilized in the container.
• Its key function is to whiten coffee, but it is also used in the preparation of food products and beverages that are meant for direct consumption.
• The important quality criteria are taste, whitening power and stability in hot coffee.

Sour Cream

• This is a heavy-bodied ripened cream of high acidity with clean flavour and smooth texture. It should have following organoleptic criteria:
• Appearance: White to yellowish, slightly creamy
• Flavour: Clean, slightly acidic, rich and Taste: Clean and milk-sour

CREAM PRODUCTS

Clotted Cream

• Clotted cream is rich, containing 60-70% fat and the fat present in cream is in a finely emulsified form, rendering it digestible
• It shows a peculiar boiled taste and rough appearance, and will exhibit a white-flaked surface

Canned or Sterilized Cream

• Canned cream possesses a peculiar flavour due to its processing and high viscosity due to homogenization
• Texture is smooth and should be free from lumpiness and separation of serum
• Sterilization spoils its whipping quality. The fat content is about 20-25%, and SNF content may vary between 6.5-9.5%.

Plastic Cream

• Plastic cream is highly viscous than any other type of cream
• Its texture resembles to paste and fat content is between 65 and 85%. It can be used directly for the manufacture of butter-oil
• This is obtained by:
• re-separating normal cream (30-40% fat) in a normal cream separator, or by
• separating milk in specially designed ‘plastic cream separator’
• In both the above cases, the initial product is pasteurized at about 71-77 °C for 15 m and cooled to 60-66 °C before separation

Whipping Cream

• Whipping cream is one of the food foam and contains 35-40% fat
• It is widely accepted due to its multiple applications in decorating and refining of food
• The cream is usually whipped immediately prior to consumption, either by the consumer or in catering outlets (restaurants, bakeries and others)
• It is therefore, primarily designed to be beaten into foam, often with added sugar and mostly available as a pasteurized product in small bottles, plastic cups, or large cans
• It is also sold as in-can sterilized cream, and even supplied with sugar and a driving gas in an aerosol-can that delivers a ready-whipped cream

Butter:

• Butter is a dairy product with high butterfat content - solid when chilled and at room temp. and liquid when warmed. It is a water-in-oil emulsion resulting from an inversion of the cream, an oil-in-water emulsion; the milk proteins are the emulsifiers. It is made by churning fresh or fermented cream or milk after separating the butterfat from the buttermilk.
• It is generally used as a spread and consists of trace amount proteins and water with/out salt.

BUTTER: Composition, principle of churning, processing of butter, temperature treatment of fat, packaging, storage, defects

• As per FSSAI (2011), butter means the fatty product derived exclusively from milk of cow and/or buffalo or its products principally in the form of water-in-oil type of an emulsion.
• The product may be with or without added common salt and starter cultures of harmless lactic acid and/or flavour producing bacteria.
• Table butter is obtained from pasteurised milk and milk products after adequate heat treatment to ensure microbial safety.
• It should be free from animal fat, vegetable and mineral oil and should have pleasant taste and flavour free from rancidity. It may contain added flavours and food additives

Fig. Structure of Butter

Table . The major constituents of butter.

In addition, butter also contains fat-soluble vitamins A, D and E.

• As per PFA rules (1976), table /creamy butter should contain not less than 80% fat, not more than 1.5% curd and not more than 3% common salt.
• Butter should have a uniform color, be dense and taste clean.
• The consistency should be smooth so that the butter is easy to spread and melts readily on the tongue.

Fig. Butter making process

CONTINUOUS FLOTATION CHURN

Fig. 7 Schematic diagram of a continuous Butter Churn

Fig. Continuous Butter Churn (Exterior view)

Fig. Continuous Butter Churn

TEMPERATURE TREATMENT

• Before churning, the cream is subjected to a program of temperature treatment, which controls the crystallization of the fat, so that the butter will have the desired consistency.
• The consistency of butter (hardness, viscosity, plasticity and spreadability) is one of its most important quality as it affects the taste and aroma.
• Relative amounts of FAs with high melting points determine whether the fat will be hard or soft. Soft fat has a high content of low-melting FAs and at room temp. has a large continuous phase of liquid fat, i.e. the ratio of liquid to solid fat is high. In a hard fat, ratio of liquid to solid fat is low.
• In butter-making, if the cream is always subjected to the same temperature treatment, it will be the chemical composition of the milk fat that determines the consistency of the butter. Soft milk fat will result in soft and greasy butter, whereas butter from hard milk fat will be hard and stiff.
• The consistency of the butter can be optimized if the temp. treatment is modified to suit the iodine value of fat. The temp. treatment regulates the amount of solid fat to a certain extent –major factor that determines the consistency of the butter.

Table. Principal temperature programs adjusted to the iodine value and recommended volumes of culture, when used

Treatment of hard fat:

• If iodine value is low, i.e. butter is hard, as much as possible the hard fat must be converted to a fewer crystals, ----little of liquid fat is bound.
• The liquid fat phase in the fat globules will thereby be maximized and much of it can be pressed out during churning and working, resulting in butter with a relatively large continuous phase of liquid fat.
• The program of treatment necessary to achieve this result comprises the following stages:
• rapid cooling to 8°C and storage for about 2 hours at this temperature
• heating gently to 20 - 21°C and storage at this temperature for 2 hours (water at 27 - 29°C is used for heating)
• Cooling to about 16°C

Treatment of medium-hard fat: With an increase in the iodine value, the heating temperature is accordingly reduced from 20-21°C. Consequently, a larger number of fat crystals will form and the more liquid fat will be adsorbed than is the case with the hard-fat program. For iodine values up to 39, the heating temperature can be as low as 15°C.

​

Treatment of very soft fat: Where the iodine value is greater than 39-40 the "summer method" of treatment is used. After pasteurization, the cream is cooled to 20°C. If the iodine value is around 39 - 40 the cream is cooled to about 8°C, and if 41 or greater to 6°C. It is generally held that aging temperatures below the 20°C level will give a soft butter.

PRINCIPLE OF CHURNING

Foam theory: According to this theory, the presence of foam is essential for churning. It also postulates that there is a ‘foam- producing’ substance in cream which gradually solidifies as the cream is agitated.

Foam is created during churning. The fat globules due to surface tension effects tend to concentrate and clump on the foam bubbles. The foam producing substabce assumes a solid character and the form collapses, the fat globules then coalesce and butter if formed.

Phase Reversal Theory: According to this theory, churning is a phase reversal, i. e., changing an oil-in-water emulsion to water-in-oil emulsion.

Agitation of cream during churning causes coalescence and clumping of fat globules until eventually the ration of the surface area to the volume of fat units become so small that it can no longer contain all the buttermilk in stable form.

Modern theory: In cooled cream at churning temperature, the fat is present as clumps of fat globules and within each globule, it is present partly in solid and partly in liquid form.

Churning breaks up the clusters and causes foam formation. The globules become concentrated to some extent.

The movement of the globules over one another in the foam film causes a gradual wearing away of the emulsion-protecting surface layer of the pospho-lipid complex. The globules then adhere to form larger and larger particles, eventually in form of butter

AMF or Butteroil or Ghee:

• Anhydrous milk fat and butteroil are products consisting of more or less pure milk fat. Ghee, a milk fat product with some protein fractions and a more pronounced flavour than AMF, has been known in Indian sub- continent for centuries.
• AMF, milkfat, anhydrous butteroil and butteroil are fat rich products derived exclusively from milk and/or products obtained from milk by almost total removal of water and non‑fat solids.
• Ghee, on other hand, is a product exclusively obtained from milk, cream or butter, by nearly total removal of water and non‑fat solids, with an especially developed flavour and physical structure.

- Anhydrous milk fat must contain at least 99.8 % milk fat and be made from fresh cream or butter. No additives are allowed for neutralization of free fatty acids.

- Anhydrous butteroil must contain at least 99.8 % milk fat, but can be made from cream or butter of different ages. Use of alkali to neutralize free fatty acids is permitted.

- Butteroil must contain 99.3 % milkfat. Raw material and processing specifications are the same as for anhydrous butteroil.

- Ghee must contain 99.5% milkfat and should have characteristic flavour

Fat spread:

• A fat spread is a food in the form of an emulsion (mainly of the water-in-oil type), comprising principally an aqueous phase and edible fats and oils.

Margarine:

• Margarine consists of a water-in-fat emulsion, with tiny droplets of water dispersed uniformly throughout a fat phase in a stable crystalline form. In general, margarine must have a minimum fat content of 80% to be labelled as such, the same as butter.
• It is fat rich product with minimum of 80% fat (80- 95%) with just 3% contribution from milk fat, so vegetable oils are the main ingredients.

Edible fats and oils:

• Foodstuffs mainly composed of triglycerides of fatty acids. They are of vegetable, animal, milk or marine origin.

Table 1. Essential composition of milk fat and margarine products

Table 2. Names of milk fat and margarine products

QUIZ-II: Prepare short report on the following respective heading