Beginning to cool__________

Cooled__________ APM; to__________

Acidity: After pasteurization__________

When inoculated________________

+INOCULATION:+

Time__________ Temperature__________

Amount__________ lbs. __________%

+INCUBATION:+

Temperature__________ Time__________

+MOTHER STARTER USED:+

Source_____________________________________ % used_______________

Times propagated___________________________ Acidity______________

Amount used________________________________ Appearance___________

Flavor_______________________________

Comments__________________________________________________________

+STARTER:+

Time of examining__________

Temperature________________

+SCORE-CARD:+

Flavor__________50

Clean, desirable acid.

Aroma___________20

Clean, agreeable acid. No undesirable aroma.

Acidity_________20

0.6%-0.75%.

Body____________10

Before breaking up: jelly-like, close,

absence of gas holes. No free whey.

____

___After breaking up: smooth, creamy, free from

granules or flakes.

Total_________ 100

----------------------------------- The above is a tentative score-card.

+COMMENTS:+____________________________________________________ _______________________________________________________________ _______________________________________________________________ _______________________________________________________________

+Work and observation by+______________________________________

+75. The amount of starter to use+ depends on the amount of acid desired in the milk for any particular kind of cheese. The great abuse of starter is the practice of using too much. It is better and safer to add starter a little at a time and several times than to add too much at once. When starter is added to milk for cheese-making, it should be strained to remove any lumps; otherwise an uneven color is likely to result.

+76. Starter lot-card.+--For certain dairy operations, a permanent record is desired. This is especially true in the making of starter and certain varieties of cheese. A lot-card not only serves as a record but also points out the succeeding steps of the operation. This latter is especially useful for beginners and students. Page 53 shows a desirable lot-card to be used when making starter. Each operation has been referred to the page in the text where it is discussed. This makes this particular lot-card an index to the whole process of starter-making as here treated.

CHAPTER V

_CURD-MAKING_

Aside from the purely sour-milk cheeses, the coagulum or curd resulting from rennet action is the basis of cheese-making. The finished cheese, whatever its final condition, is primarily dependent on a particular chemical composition and fairly definite physical characters in the freshly made curd ma.s.s. These characters are determined by a series of factors under control of the cheese-maker. a.s.suming the milk to be normal in character, success depends on the use of a proper combination of these factors. The possible variations in each factor together with their number makes an almost infinite series of such combinations possible. The essential steps in the process are, therefore, presented as underlying all cheese-making. The special adaptations of each factor are considered in the discussion of the varieties group by group.

These factors follow:

_A._ The coagulation group:

1. Fat-content of the milk.

2. The acidity of the milk.

3. The temperature of renneting.

4. The effective quant.i.ty of rennet.

5. Curdling period or the time allowed for rennet action.

_B._ The handling group:

6. Cutting or breaking the curd.

7. Heating (cooking) or not heating.

8. Draining (including pressing, grinding and putting into hoops or forms).

+77. The composition of the milk.+--The fat percentage in the milk in the cheese-vat should be known to the cheese-maker and be strictly under his control. The fat tester and the separator make this clearly possible. He can go further. Milk from particular herds whose quality is a matter of record from the routine test of each patron's milk may be selected and brought together for the manufacturer of cheese of special quality. Control of casein or lactose, on the contrary, is not nearly so practicable. The purchase of milk on the fat test has become so well established in most dairy territories, as to insure the presence and constant use of the tester. A fat test of the mixed product in the cheese-vat in connection with established tables thus insures an accurate knowledge of the materials which go into each day's cheese. For some varieties of cheese, whole milk should always be used. For other varieties, the addition or removal of fat is regularly recognized as part of the making process. The presence of added fat or the removal of fat affects the texture of the product and the details of the process of making.

+78. Cheese color.+--An alkaline solution of annatto is usually used as a cheese color. This colors both casein and fat in contrast to b.u.t.ter color which is an oil solution of the dye and mixes only with the fat.

Cheese color is added to the milk in making some varieties of cheese, and not for others. When lactic starter is used, the color should be added after the starter and just before the addition of the rennet. The amount is determined by the color desired in the cheese. The usual amount varies from one to four ounces to each thousand pounds of milk.

Before adding, the color should be diluted in either milk or water, preferably water. It should then be mixed thoroughly with the milk.

+79. The acidity factor.+--Milk as drawn shows a measurable acidity when t.i.trated to phenolphthalein with normal sodium hydroxide. This figure varies with the composition of milk. Casein itself gives a weakly acid reaction with this indicator. Calculated as lactic acid, this initial acidity varies within fairly wide limits, records being found from 0.12 to 0.21 of one per cent or even more widely apart. Commonly, however, such t.i.tration shows 0.14 to 0.17 per cent. Some forms of cheese (Limburger, Swiss, Brie) are made from absolutely fresh milk. Acidity from bacterial activity is important as a factor in the making of most types of cheese and probably in the ripening of all types.

Increasing the acidity of the milk hastens rennet action and within limits produces increased firmness of the curd. If carried too high, acidity causes a grainy or sandy curd. Normally fresh milk is sufficiently acid in reaction when tested to phenolphthalein to permit rennet to act, but the rate of action increases rapidly with the development of acid. Increase of acidity may be accomplished: (_a_) by the addition of acid as has been done by Sammis[25] and Bruhn in pasteurized milk for Cheddar cheese; or (_b_) by the development of acid through the activity of lactic organisms, which is the usual way. For renneting, the acidity necessary for particular cheeses runs from that of absolutely fresh milk still warm (as in French Brie, Limburger, Swiss, Gorgonzola) through series calling for increase of acidity, hundredth by hundredth per cent calculated as lactic acid. This ranges from 0.17 to 0.20 per cent as is variously used in American factory Cheddar to about 0.25 to 0.28 per cent as obtained by adding acid in Sammis' method. This method is discussed under the heading "Cheddar Cheese from Pasteurized Milk" (p. 229) since it requires special apparatus and has not thus far been used with other types of cheese. For the development of acidity by the action of bacteria, lactic starter is almost universally used. This may be added in very small quant.i.ties and the acidity secured by closely watching its development or by adding starter in amount sufficient to obtain the required acidity at once. In either case, the cheese-maker needs to know the rate of action of the culture to insure the proper control of the process. The amount of acid already present when the rennet is added affects not only the texture of the curd as first found, but within limits indicates also the rate at which further acidity may be expected to develop.

A series of experiments in making Roquefort were tabulated to show the rate of acidification from various initial points. In the graphs (Fig.

8) the curves for acid development are parallel after the determination reaches 0.30 per cent. These experiments were made at a temperature 80 to 84 F. Milk at the lowest acidities tried developed t.i.tratable acid very slowly. A period of several hours was required to produce sufficient acid to affect the curd texture. When the acid reached 0.25 per cent by t.i.tration, the further rise was rapid and all the lines became almost straight and parallel after the t.i.tration reached 0.30 per cent. If this rapid souring occurred after the completion of the cheese-making process, the texture of the experimental cheese was not measurably affected. In those cases, however, in which 0.30 per cent was reached before the cheese reached its final form in the hoop, the texture of the ripened cheese was entirely different from that desired for this variety under experiment. These curves apply directly to but one cheese process in which a particular combination of acidity, rennet and time is used to obtain a very delicately balanced result. In other varieties it is equally important to obtain exactly the adjustment of these factors which will bring the desired result.

[Ill.u.s.tration: FIG. 8.--The acidification of Roquefort cheese.]

+80. Acidity of milk when received.+--If proper care has been taken, milk should be delivered to the factory fresh, clean and without the development of acid. If the milk has not been handled properly, the early stages of souring or some other unfavorable fermentation will have developed. Such milk may develop too much acid, or gas, or any one of several objectionable flavors during the making and ripening of the cheese. Some cheese-makers become very expert in detecting the first traces of objectionable qualities, but most makers are dependent on standardized tests to determine whether milk shall be accepted or rejected, and when accepted to determine the rate at which it may be expected to respond during the cheese-making process.

Various tests have been devised to determine the amount of acid present in milk. There are two tests commonly used in cheese-factories. One is known as the "acid test" and the other the "rennet test."