In this article we will discuss about:- 1. Introduction to Cheese 2. Definition of Cheese 3. History 4. Scientific Basis of Cheese Making 5.Classification 6. Composition 7. Food and Nutritive Value 8. Moisture Control 9. Freezing 10. Distribution of Milk-Constituents 11. Packaging 12. Storage 13. Judging and Grading 14. Uses.
Contents:
- Introduction to Cheese
- Definition of Cheese
- History of Cheese
- Scientific Basis of Cheese Making
- Classification of Cheese
- Composition of Cheese
- Food and Nutritive Value of Cheese
- Moisture Control in Cheese
- Freezing of Cheese
- Distribution of Milk-Constituents in Cheddar Cheese and Whey
- Packaging of Cheese
- Storage of Cheese
- Judging and Grading of Cheese
- Uses of Cheese
Introduction to Cheese:
Cheese, like butter, also functions as the balance wheel of the dairy industry in developed dairying countries. The world’s recorded annual cheese production in 1969 has been estimated to be 6.8 million tonnes. An insignificant amount of milk is annually converted into cheese in India, mainly of the cheddar type.
The manufacture of cheese did not develop in India during the past mainly because animal rennet could not be used by Indians (mostly Hindus), who considered cow slaughter sinful. However, they discovered a plant known as Withania coagulans, the seeds of which coagulated milk, and this helped in the preparation of Indian cheese or panir on a very limited scale.
The non-acceptability of rennet even today by the vast majority of the population (consisting of orthodox vegetarians) together with a lack of taste for cheese, besides certain other factors, have impeded the growth of the industry in this country.
Definition of Cheese:
Cheese has been defined by Davis as a product made from the curd obtained from milk by coagulating the casein with the help of rennet or similar enzymes in the presence of lactic acid produced by added or adventitious micro-organisms, from which part of the moisture has been removed by cutting, cooking and a pressing, which has been shaped in a mould, and then ripened by holding it for some time at suitable temperatures and humidities.
According to the PFA Rules (1976), (hard) cheese means the product obtained by draining after the coagulation of milk with a harmless milk coagulating agent, under the influence of harmless bacterial cultures. It shall not contain any ingredients not found in milk, except coagulating agent, sodium chloride, calcium chloride (anhydrous salt) not exceeding 0.02 per cent by weight, annatto or carotene colour; and may contain certain emulsifiers and/or stabilizers, namely citric acid, sodium citrate or sodium salts of orthophosphoric acid and polyphosphoric acid not exceeding 0.2 per cent by weight; wax used for covering the outer surface should not contain anything harmful to the health.
In case the wax is coloured, only permitted food colours may be used. Hard cheese shall contain no more than 43.0 per cent moisture and not less than 42.0 per cent milk fat of the dry matter. Hard cheese may contain 0.1 per cent of sorbic acid or its sodium, potassium or calcium salts: or 0.1 per cent of nicin.
History of Cheese:
Cheese is one of the oldest foods of mankind. It was a prominent article of the Greek and Roman diet as much as 2500 years ago. It is referred to in the Old Testament several times. Probably cheese was made accidentally in the stomachs of animals carrying milk, when milk-clotting enzymes of the stomach converted the liquid milk into a solid mass or junket.
Until 1850, cheese was made in the ‘farmhouse’. The period 1860-80 saw the introduction of the ‘factory system’ throughout the cheese-making world.
Cheddar cheese originated in the town of Cheddar located in the county of Somerset in south-western England. Cheddar is probably the best-known cheese in the world; many variants are now recognized, such as American, Australian, New Zealand, Canadian and Indian Cheddar.
Modern cheese-making technology has advanced through the years as shown below:
About 1870:
Commercial rennet preparation was put on the market by Hansen in Denmark.
About 1900:
i. Use of titratable acidity measurements to control acidities in cheese making.
ii. Introduction of pure cultures of lactic streptococci as ‘starters’.
iii. Pasteurization of cheese milk to destroy pathogenic micro-organisms.
iv. Refrigerated curing of cheese.
v. Processed cheese making.
vi. Mechanization of cheese making.
vii. New methods of packaging.
Scientific Basis of Cheese Making:
This has been stated by Davis as follows:
(a) All cheeses, irrespective of country of origin and methods of manufacture, possess certain characteristics in common:
(i) They are made from the milk of certain mammals;
(ii) The first stage is souring ripening;
(iii) The second stage is clotting/coagulation by rennet or a similar enzyme preparation;
(iv) The third stage is the cutting or breaking up of the coagulum or junket to release the whey;
(v) The fourth stage is the consolidation or ‘matting’ of the curd;
(vi) The fifth stage is the maturing, curing of green cheese in some type of container.
(b) The above five stages are common to all cheeses, but the conditions vary considerably.
The chief factors responsible for differences in the final cheese are:
(i) The type of milk used;
(ii) The degree of souring and the type of souring organisms added;
(iii) The temperature of renneting and subsequent ‘cooking’ of the curd in the whey;
(iv) The method and fineness of cutting or of breaking up the curd;
(v) The treatment of the curd after separation from the whey;
(vi) The milling and salting of the curd before placing it in the hoop or mould;
(vii) The pressure applied to green cheese.
(viii) The time, temperature and relative humidity of curing:
(ix) Special treatment such as pricking or stabbing the cheese, bathing in brine, and surface treatment to produce a certain type of coat.
(c) These variables, which are under the control of the cheese maker, all exert an influence on the physical, chemical and micro biological changes which take place successively in the milk, coagulum, curd and cheese.
(d) From the scientific point of view, cheese making is essentially the controlled syneresis of the rennet milk coagulum, the expulsion of moisture being affected by:
(i) Acid development—the pH falling from 6.6 to about 5;
(ii) Warmth—the temperature being raised to 31°C (88°F) for renneting and to about 38°C for cooking the curd;
(iii) Repeated cutting of the curd.
The combined effect of these factors is to decrease the moisture from 87 per cent in milk to about 40 per cent in green cheese.
Note:
Earlier, cheese making was done ‘by the clock’; today, it is done ‘by the acidity/pH’ test.
Classification of Cheese:
It is reported that there are probably about twenty distinct classes/ types/varieties of cheese in the world today, although they are given over a thousand different names.
Cheese can be classified according to the following systems:
(a) Geographical Considerations:
Country, valley, institution, town or region where first produced/marketed.
(b) Type of Milk:
Cow, sheep, goat, buffalo.
(c) Method of Manufacture:
Temperature of cooking, degree of acidity, fineness of cutting, etc.; these affect moisture retention, which in turn affects firmness (hardness/softness) and also the rate of ripening.
(d) General Appearance:
Flavour, size, colour, keeping quality.
(e) Physical and Rheological Properties:
Very hard (less than 25 per cent moisture); hard (25-36 per cent moisture); semi-hard (36-40 per cent moisture): and soft (40 per cent moisture).
(f) Chemical Analysis:
Water, calcium, sodium chloride, casein, lactose, fat-acidity contents.
(g) Microbiological Properties:
Bacteria-ripened, mould-ripened, unripened, etc.
Note:
The factors that influence the resultant cheese from a given lot of milk are- types of organisms added, enzymes added, acid development, temperature and time used for cooking the curd, amount of salt added, moisture content of cheese, etc.
Composition of Cheese:
The average composition of some of the important varieties of cheese is given in Table 7.2.
Food and Nutritive Value of Cheese:
Cheese has high food and nutritive value:
(i) It is an excellent source of milk proteins;
(ii) A rich source of calcium and phosphorus;
(iii) An excellent source for several fat-soluble vitamins, such as A, D, E and K;
(iv) A concentrated form of energy; cheddar cheese gives about 400 calories/100 g;
(v) Is both palatable and digestible; there is practically no waste.
Moisture Control in Cheddar Cheese:
The following considerations are involved:
(a) Coagulation Period:
An increase in the coagulation period tends to increase the moisture content of cheese, and vice versa.
(b) Curd Particle Size:
An increase in the curd particle size for cooking increases the moisture content of cheese, and vice versa.
(c) Cooking Temperature:
Although a rise in the (maximum) cooking temperature causes an increased rate of moisture expulsion, it also reduces the rate of acid production by the starter which has the reverse effect on moisture expulsion; hence the overall effect is rather variable.
(d) Dry Stirring before Cheddaring:
This tends to reduce the moisture content.
(e) Cheddaring:
The smaller the size of the cheese blocks, the greater the moisture loss during cheddaring. On the other hand piling of cheese blocks encourages moisture retention in cheese.
(f) Salting:
More salts expel more moisture, and vice versa.
(g) Curd Treatment after Salting Prior to Pressing:
An increase in the time between salt-addition and hooping decreases the moisture content of cheese, and vice versa.
Freezing of Cheese:
Freezing of cheese may damage its texture. Whereas in fresh cheese the substances dissolved in the moist portion include lactose, milk salts and sodium chloride, as the cheese cures, increasing amounts of water-soluble protein-degradation compounds are added. There is also a gradual decrease in moisture due to evaporation.
Thus the percentage concentration of substances dissolved in cheese-moisture gradually increases and the freezing point is continually lowered as curing progresses. On average, the freezing point of cheddar may be —4.5°C (24°F) in fresh cheese and – 14.5°C (6°F) in cheese more than a year old.
Yield:
This is affected by- the quality of milk, nature of manufacturing operations, the skill of the manufacturer, and curing procedures.
More specifically the yield of cheese depends on:
(i) Composition of milk, mainly the content of cheese solids (i.e., casein and fat).
Note:
An extra 1 kg. casein increases the yield of cheese by 2.5 to 2.75 kg., since each 1 kg. of casein carries 1.5 to 1.75 kg. of moisture; on the other hand, an extra 1 kg. fat increases the yield by only 1 kg.
(ii) Quantity of milk constituents lost in whey;
(iii) Amount of sodium chloride added during the making process (a minor part of which is lost in whey after salting);
(iv) Amount of water retained in cheese.
The yield of cheddar cheese is given by the following formula (vide Van Slyke):
Y = (F + C) N,
Where
Y = kg. cheese per 100 kg. milk
F = kg. fat per 100 kg. milk
C = kg. casein per 100 kg. milk
N = 1.63 for green cheese
= 1.555 for cured cheese.
Distribution of Milk-Constituents in Cheddar Cheese and Whey:
The average figures are given in Table 7.5.
Packaging of Cheese:
Packaging of cheese refers to its being placed in a protective wrapper or container for transport or storage.
Requirement:
Any material to be used for packaging natural cheeses should:
(i) Afford general protection;
(ii) Prevent moisture loss;
(iii) Improve its appearance;
(iv) Protect it against micro-organisms; and
(v) Prevent oxygen transmission.
Modern Packaging Materials and Forms:
Materials:
The basic ones for cheeses are paper (usually coated or lined); vegetable parchment; foil (usually aluminium); and plastics such as polyethylene (polythene), polypropylene, treated cellulose and cellulose acetate (cellophane), polystyrene, polyester, polyamide (nylon), rubber hydrochloride (pliofilm), polyvinyl chloride, polyvinyledene chloride (cryovac) and saran (a mixed polymer). Laminates are now more common.
Forms:
The common forms for cheeses are cans (lacquered or lined with plastics), bags/pouches, glass jars, etc.
Film Packaging:
This is synonymous with rind less cheese. Green cheeses of uniform size and shape are ripened in bags made of plastic films; these cheeses may be placed in wooden boxes to preserve their shape.
Merits:
(i) It affords a considerable saving in labour required for paraffining, turning while curing, etc.;
(ii) It protects the cheese from attacks by moulds, insects, rodents and fault-inducing micro-organisms;
(iii) It is easily applied, and the method can be readily mechanized;
(iv) There is practically no shrinkage while curing;
(v) The method is suitable for packaging small quantities, which makes handling and retail trade easier;
(vi) The method is most easily applied to rectangular blocks;
(vii) It is cheap and convenient;
(viii) Humidity control is not necessary during ripening and storage;
(ix) More cheese can be stored in a given volume;
(x) Turning is not necessary during ripening;
(xi) It permits rindless curing so that the whole cheese can be eaten. (When rind is formed as in the traditional method, the loss can be as high as 10 per cent.)
Demerits:
(i) Not all technical problems in film packaging have been solved. For example, the new methods fail to obtain a perfect seal and to remove all air, which may in turn result in mould growth.
(ii) The moisture content of the cheese at packaging must be smaller than that for traditional packaging and must be carefully standardized. Failure to do so may lead to the growth of taint- producing organisms.
(iii) The ripening process in some cheeses (such as camembert) may be affected.
(iv) The film does not always give the same mechanical protection to cheese as traditional methods.
(v) The most careful attention to detail is necessary in film packaging.
Packaging of Raw and Processed Cheese:
Broadly speaking, there are two main types of packaging requirements, viz., the ‘long- term’ wrap for factory packaging and the ‘short-term’ wrap for retail sale. For the former, waxed cellulose and nylon films, and cellulose-pliofilm, cellulose-polythene, pliofilm-polythene, polythene- polyester laminates have found favour; for the latter, pliofilm, cryovac, saran, polyvinyl and chloride are suitable.
Due to improved keeping quality, the packaging requirement for processed cheese is less critical. Wax-coated cellophane, laminates with a heat-sealable layer and foil-composite with cellophane or paper laminated on the outer surface are generally used. Hot cheese is poured into pre-formed pouches and the sealed package is tight, mould-resistant and inexpensive. Canning is rather expensive. Processed cheese spreads are packaged in glass jars, paper-board cartons with foil overwraps and rigid vacuum-formed polythene tubs.
Automatic packaging machinery has allowed cheese packers to eliminate all hand wrapping, and cheese packages may be formed from either roll-stock or pre-fabricated pouches.
Storage of Cheese:
Natural cheeses should be stored at low temperatures, preferably 0 to 1°C (32 to 34°F), to ensure good quality. A high temperature leads to evaporation of moisture, growth of unwanted moulds and taint-producing bacteria, and other faults. A very low temperature also leads to mould growth (because of the relatively high humidity usually associated with it) and may result in damaged texture. Processed cheese may be stored at 5-10°C (40-50°F).
Judging and Grading of (Cheddar) Cheese:
Score Card:
This is given (for cheddar cheese) in Table 7.9.
Procedure of Examination:
(a) Tempering Cheese:
Before judging, cheese should be tempered by holding it at 10-15°C (50-60°F) for a sufficient length of time, so as to enable determination of its true body and texture characteristics.
(b) Sampling:
Take a sample with a cheese trier and hold it under the nose immediately. Then break the upper 2-3 cm. of the sample-plug (to be replaced flush with the surface of the cheese and later brushed with melted paraffin).
Sequence of Observations:
(i) Appearance:
Before sampling, look for a neat, attractive appearance, evenness of surface, smoothness of paraffin coating, mould spots, cracks in rind, etc., on the cheese-block.
(ii) Colour:
Observe the colour of the cheese-plug: whether bright and clear, dull and lifeless, uniform and free from mottles, etc.
(iii) Body and Texture:
Note the body by bending the plug and observing the nature of the break; then take one of the broken pieces and work it up between thumb and forefingers. Observe whether the mass feels smooth, silky, waxy, sticky, pasty, mealy or crumbly. Observe the texture by noting the nature and size of the opening and whether they are regular, rounded, large or small.
(iv) Flavour:
Observe the flavour and aroma by placing the worked-up mass under the nose and noting its aroma; compare this with the aroma observed during sampling. Then place a small portion of the unworked plug into the mouth, chew it to a semi-liquid, and note the flavour (smell and taste).
Note:
Rinse mouth with saline water frequently.
Requirements for High-Grade Cheddar Cheese:
The ‘ideal’ requirements for high-grade cheddar cheese are:
(i) Colour:
Uniform; light amber to ivory; not artificially coloured.
(ii) Finish and Appearance:
Smooth; unbroken rind; a neat, clean, attractive appearance.
(iii) Body:
Slightly elastic; breaks slowly when plug is bent; firm but not hard when crushed between the fingers.
(iv) Texture:
Compact; continuous and homogeneous; free from openings, holes, breaks, cracks or fissures.
(v) Flavour:
Clean, pleasing aroma; mildly salted in taste; when fully aged, causes a pleasant tingling sensation within the mouth; after cheese is swallowed, leaves pleasing after-taste resembling the flavour of sweet nuts.
Uses of Cheese:
(i) Direct consumption as such or in sandwiches;
(ii) In the preparation of special dishes (added in cut or grated form);
(iii) In the preparation of sauce.