Other than the heat-acid precipitated cheese (Chapter 9.5), there are five principal types of acid coagulated fresh cheese: (1) Cottage cheese (North American); (2) Quark types such as Baker’s cheese (European); (3) Cream cheese; (4) fresh lactic cheese such as ‘Chevre’; and (5) ripened lactic cheese such as Valençay and Chaource. More accurately, these varieties can be described as predominantly acid coagulated, because for many varieties in this category, small amounts of rennet are used to improve the texture. This section describes several varieties that are normally acidified by lactic acid fermentation.

1. Cottage cheese – Short Set

Manufacturing procedures may differ considerably and still yield a high-quality product. They differ chiefly in temperature of setting and in amounts of starter and rennet. Procedures differ also in the size of curd, creaming rates, type of cream, the degree of “cottage cheese flavour”, and added condiments.

Milk

Cottage cheese is made from pasteurized skim milk. Minimum legal pasteurization treatment is 72°C for 16 s. Greater heat treatment denatures more whey protein which participates in the formation of the acid coagulated gel resulting in higher yield. However, the denature whey proteins also create a more brittle curd that results in loss “fines” in the whey and less desirable texture.

Procedure

1. Pasteurize skim milk (72°C for 16 s or 62.5°C for 30 min) and cool to 32°C.
2. Add sufficient mesophilic DVS to acidify the milk to pH 4.6 within 5 – 6 h. For long set cottage cheese, add sufficient mesophilic DVS to acidify the milk to pH 2.6 within 12-16 h. Normally, Lactococcus lactis and/or cremoris cultures are used, but certain cottage cheese culture blends also contain Streptococcus thermophilus. Stir well for 10 – 15 min. It is important that the culture is not gassy (not heterofermentative) and that it does not produce ropiness. Ropy texture is due to excretion of polysaccharides by certain lactic acid bacteria.
3. About 90 minutes after inoculation, add 50 IMCU of rennet per 100 Kg of skim milk. Mix for two minutes. Leave the milk undisturbed while ripening. If the A-C test (see below) is used to determine the cutting time, take the A-C test sample before adding the rennet.
4. Determine the cutting time using pH measurements of the curd or via the A-C test. Optimum values for pH at cutting depend on the heat treatment and composition (total solids) of the skim milk. Generally, pH of 4.80 in the curd can be used for normal skim milk when rennet is used. Use 1.2 cm (3/8”) knives.
5. After cutting, allow the curd to rest undisturbed for 15 to 20 min.
6. Raise the temperature of the heating water at a rate such that the temperature in the vat rises 0.5°C each 5 min for the first 30 min. After this, the rate may be doubled and eventually tripled until a final cooking temperature of 54 – 57°C is reached about 2 hours later. Stirring should be gentle to prevent shattering, yet sufficiently vigorous to prevent matting. If both matting and shattering occur, the rate of heating is probably too fast.
7. The proper firmness should be reached after holding 15 to 20 minutes at 54 – 57°C. The curd should be checked frequently during cooking to ensure that it does not become too firm. The pH or acidity at cutting is the chief factor influencing the firmness of curd at the final cooking temperature. If curd is consistently too firm at 54 – 57°C, the cutting pH should be lowered slightly. If curd is consistently too soft at 54 – 57°C, the cutting acidity should be lowered, or the cutting pH should be raised slightly. Judge firmness of curd after cooling in water to 15 – 20°C.
8. After cooking, drain the whey until the whey first disappears below the surface of the curd mass, and then add the first wash water, enough to replace the whey removed. If three wash waters are used, the first is at 20 – 25°C, the second at 10°C and the third at 1.5 – 5°C. If two wash waters are used, the first is at 15°C and the second at 1.5 – 5°C. The curd should remain in contact with each wash for 15 – 20 min and should be stirred frequently but carefully.
9. Trench the curd carefully while draining the final wash water. Continue draining until the free water has completely drained (30-60 min).
10. Add salt (1% of the weight of curd) either directly to the curd or in the cream.
11. Add homogenized cream (18%) to give 4% fat in the creamed curd. If cream of lower fat content is used, it is necessary to increase its viscosity using stabilizers to prevent excess free cream in the curd.

Expected yield: 6 x casein content or about 14 – 16%.

The A-C Test

1. Add starter to the skim milk in the vat. Mix well.
2. About 90 minutes after inoculation, place a sample of the well-mixed starter and skim milk in the A-C test beaker.
3. Add rennet to the skim milk in the vat immediately after taking the A-C test sample. Mix well.
4. Immediately suspend the A-C test beaker in the vat so that the surface of the skim milk in the beaker is a little below that in the vat. Cover the vat.
5. Periodically check the vat for coagulation. After it is coagulated, begin to check the A-C beaker for coagulation with a spatula or thin knife with as little disturbance of the skim milk as possible.
6. As soon as coagulation in the A-C beaker is first detected, cut the coagulating skim milk 2 or 3 times with the spatula and repeat the operation at 5 min intervals.
7. Observe the surface of the A-C test samples for the appearance of fine lines of whey in the cuts made previously with a spatula. The A-C end-point is the time when the fine lines of whey first appear and usually occurs 10 – 20 min after coagulation is first detected.

Reference

Emmons, D.B. and Tuckey, S.L. 1967. Pfizer cheese Monographs -7. Cottage cheese and other cultured products. Pfizer & Co. New York, N.Y.

2. Quark

Quark (sometimes called European style cottage cheese or quarg) represents a group of soft fresh cheese of varying moisture and fat contents. The procedure described below produces a relatively firm, granular curd structure. If a smooth textured product (such as Baker’s cheese) is desired, the pH at the time of breaking the curd should be 4.5 – 4.4 and no cooking is required. The soft smooth curd must then be separated in cloth bags or by a centrifuge. Quark and Cream type cheeses are now normally produced using ultrafiltration to concentrate skim milk protein before ripening, removing whey by liquid-solid centrifugation after ripening, or removing permeate by ultrafiltration after ripening.

Procedure

1. Pasteurize skim milk (72°C for 16 s or 62.5°C for 30 min) and cool to 32°C.
2. Add sufficient mesophilic DVS such as blends of Streptococcus lactis and Streptococcus cremoris to acidify the milk to pH 4.6 within 5 – 6 h. Stir well for 10 – 15 min.
3. Let milk set for 4 – 6 h until a soft gel is formed. The pH should be about 4.8, and clear whey should appear when the curd is cut with a spatula.
4. Stir gently to break up the curd and heat slowly to 52°C. Initial heating rate should not exceed 0.5°C in 5 min. Hold at 52°C until the curd is firm (about 1.5 h from the time of breaking the curd).
5. Drain most of the whey and replace it with 10°C water to leach the acid flavour from the curd. Washing may be omitted if you prefer an acid cheese. It may be convenient to drain the curd in a cloth bag, in which case, it could be washed by soaking the whole bag in cold water for 15 min.
6. Add cream or cream dressing to the curd according to taste. Suggestion: 4 – 8% using 18% homogenized cream.

3. Cream Cheese

Cream cheese according to the Food and Drug Directorate is the cheese made from cream or milk to which cream has been added. It may contain not more than 0.5% stabilizer, not more than 55% moisture, and not less than 30% milk fat.

The following procedure is a cold pack method. For greater shelf life and smoother texture, cream cheese or Neufchatel cheese can be blended with 50% cream, heated, homogenized and hot-packed. Neufchatel cheese is similar to cream cheese, but has a lower fat content. Cream cheese is now frequently made by ultrafiltration procedures.

Conventional Procedure

1. Standardize: Cream should be 11 – 20% fat. Cream of 11% fat is required to make a legal cheese.
2. Pasteurize the cream (80°C, 16 s, or 70°C, 30 min).
3. Homogenize at 1,000 – 1,500 psi (6,900 – 10,300 kPa) at 63°C and cool to 30°C.
4. Add sufficient mesophilic DVS such as blends of Streptococcus lactis and Streptococcus cremoris to acidify the cream to pH 4.6 within 5 – 6 h. Stir well for 10 – 15 min.
5. When the pH reaches pH 4.6, stir the curd thoroughly to remove lumps. Add water at 76°C directly to the curd until the temperature is 51°C. Curd should be smooth and creamy. Coarse or mealy texture at this stage may be due to low fat or lack of acid development.
6. Pour the hot curd and whey into draining bags. Sterilize the bags in boiling water before use.
7. Allow the whey to drain freely for about 2 h. After the correct consistency is obtained, salt the curd with 0.75% salt.
8. Pack the cheese in appropriate sized molds lined with Saran or plastic tabs and chill to 2°C.

Yield: 2.7 – 3.1 Kg of cheese per Kg of fat.

Flavouring: many flavouring materials may be used such as olives, nuts, mayonnaise, pickles, relish and pimento.

Reference

Emmons, D.B. and Tuckey, S.L. 1967. Pfizer cheese Monographs -7. Cottage cheese and other cultured products. Pfizer & Co. New York, N.Y.