pleteness of color development by adding a third drop; repeat the dilution procedure until the addition of an extra drop does not cause any further increase in the amount of blue color.

12. Calculation and evaluation of results. When using 0.5 gm. of sample and adding a total of 11.0 ml. of liquid, multiply the value of the reading by 1.1 to convert it to units of color or phenol equivalents per 0.25 gm. of cheese. The result may, if desired, be converted to phenol equivalents per 1 gm. by multiplying by 4.4.

IV. Photometric determination. To read the color in aqueous solution, use a filter with maximum light transmission in the region of 610 m, wave length.

To read the color in butyl alcohol, extract the color as described above. If necessary, centrifuge the sample for 5 minutes to break the emulsion and to remove the moisture suspended in the alcohol layer. A Babcock centrifuge can be adapted for this purpose by making special tube holders as follows: Slice a section 1⁄4 inch thick from a rubber stopper of suitable diameter to at in the bottom of the centrifuge cup. Glue together two cork stoppers of appropriate diameter. bore through the center a hole of proper size to hold the tube snugly, and insert the double-cork section into the cup. After centrifuging, remove nearly all of the butyl alcohol by means of a pipet with a rubber bulb on the top end. Filter the alcohol into the photometer cell and read with a filter with maximum light transmission in the region of 650 mμ wave length.

If more than approximately 4 ml. of butyl alcohol is required for the photometer used, conduct the test in a larger tube and extract the color, in both the test and the standards, with the necessary quantity of butyl alcohol rather than with 5 ml. specified above.

V. Precautions. The length of time that the crystalline disodium phenyl phosphate and the BQC powder will remain stable can be increased greatly by keeping them in the freezing chamber of a refrigerator, and by keeping them dry.

The glassware, stoppers, and sampling tools should be scrupulously clean, and it is desirable to soak them in hot, running water after cleaning.

The solid barium hydroxide and the barium buffer must be kept stoppered tightly to prevent absorption of carbon dioxide. Phenolic contamination from plastic closures on reagent bottles has been encountered, and therefore the use of plastic closures should be avoided. Rubber stoppers should not be used in flasks in which butyl alcohol is stored. Glass or cork stoppers should be used.

VI. Modifications for different cheeses. Different kinds of cheese and cheeses of different ages have different buffering capacities, and therefore some of them require modification of concentrations of the re

agents. The modifications of the barium buffer needed to produce optimal pH conditions during incubation (9.85-10.20), and of the precipitant to yield uniformly clear filtrates and to minimize interference during color development under optimal pH conditions (9.3-9.4), are specified in Table I.

With some samples, especially those of unknown history, slight deviations from the optimal pH range may occur, but such deviations do not very materially affect the results. For example, pH values as low as 9.6 or as high as 10.35 during incubation have been found to result in an average decrease of not more than 20 percent below the maximum in the quantity of phenol liberated. The use of the 25-11 buffer substrate with samples for which the 27-11 buffer substrate is specified yields pH values not lower than 9.8.

In testing cheese of unknown history or age, information as to the percentage of solids, especially the nonfat solids, is useful as an indication of the correct buffer to use; cheese with a relatively high percentage of nonfat solids generally requires the use of a relatively concentrated buffer to adjust the pH of the mixture correctly.

For precise quantitative results on unknown samples, adjust the pH to 10.0-10.05 for the incubation.

Cottage cheese curd is heated in the presence of considerable acid during manufacture, and therefore its phosphatase values are comparatively low. Alternatively, to increase the sensitivity of the test on cottage cheese, apply the following modifications: Use a 1.0-gm. sample, 27-11 buffer substrate, 2-hour incubation, and 6.0-0.1 precipitant.

(g) (1) If cheddar cheese in sliced or cut form contains an optional mold-inhibiting ingredient as specified in paragraph (d) of this section, the label shall bear the statement ". added to added retard mold growth" or as a preservative," the blank being filled in with the common name or names of the mold-inhibiting ingredient or ingredients used; e.g., "Sorbic acid and potassium sorbate added to retard mold growth."

(2) Wherever the name of the food appears on the label so conspicuously as to be easily seen under customary conditions of purchase, the statement specifled in this section, showing the optional ingredient used, shall immediately and conspicuously precede or follow such name, without intervening written, printed, or graphic matter.

[24 F.R. 6478, Aug. 12, 1959, as amended at 27 F.R. 3005, Mar. 30, 1962, 28 F.R. 5420, June 1, 1963, 29 F.R. 15811, Nov. 25, 1964, 30 F.R. 1253, Feb. 5, 1965]

§ 19.502 Cheddar cheese for manufacturing; identity.

Cheddar cheese for manufacturing conforms to the definition and standard of identity prescribed for cheddar cheese by 19.500, except that the milk is not pasteurized, curing is not required, and the provisions of paragraph (d) of that section do not apply.

[24 F.R. 6481, Aug. 12, 1959]

§ 19.505

Washed curd cheese, soaked curd cheese; identity; label statement of optional ingredients.

(a) Washed curd cheese, soaked curd cheese, is the food prepared from milk and other ingredients specified in this section, by the procedure set forth in paragraph (b) of this section, or by another procedure which produces a finished cheese having the same physical and chemical properties as the cheese produced when the procedure set forth in paragraph (b) of this section is used. It contains not more than 42 percent of moisture, and its solids contain not less than 50 percent of milk fat, as determined by the methods prescribed in § 19.500 (c). If the milk used is not pasteurized, the cheese so made is cured at a temperature of not less than 35° F. for not less than 60 days.

(b) Milk, which may be pasteurized or clarified or both, and which may be warmed, is subjected to the action of harmless lactic-acid-producing bacteria, present in such milk or added thereto. Harmless artificial coloring may be added. Sufficient rennet (with or without purified calcium chloride in a quantity not more than 0.02 percent, calculated as anhydrous calcium chloride, of the weight of the milk) is added to set the milk to a semisolid mass.

washed curd cheese may be added during the procedure, in such quantity that the weight of the solids of such preparation is not more than 0.1 percent of the weight of the milk used.

(c) For the purposes of this section: (1) The word "milk" means cow's milk, which may be adjusted by separating part of the fat therefrom or by adding thereto one or more of the following: Cream, skim milk, concentrated skim milk, nonfat dry milk, water in a quantity sufficient to reconstitute any concentrated skim milk or nonfat dry milk used.

(2) Milk shall be deemed to have been pasteurized if it has been held at a temperature of not less than 143° F. for a period of not less than 30 minutes or for a time and at a temperature equivalent thereto in phosphatase destruction.

Washed curd cheese shall be deemed not to have been made from pasteurized milk if 0.25 gm. shows a phenol equivalent of more than 3 micrograms when tested by the method prescribed in § 19.500 (f).

(3) During the cheese-making process the milk may be treated as provided in § 19.500(e) (3).

(d) Washed curd cheese in the form of slices or cuts in consumer-sized packages may contain an optional mold-inhibiting ingredient consisting of sorbic acid, potassium sorbate, sodium sorbate, or any combination of two or more of these, in an amount not to exceed 0.3 percent by weight, calculated as sorbic acid.

(e) (1) If washed curd cheese in sliced or cut form contains an optional moldinhibiting ingredient as specified in paragraph (d) of this section, the label shall bear the statement "

46

so cut, stirred, and heated with continued stirring, as to promote and regulate the separation of whey and curd. The whey is drained off, and the curd is matted into a cohesive mass. The mass is cut into slabs, which are so piled and handled as to promote the drainage of whey and the development of acidity. The slabs are then cut into pieces, cooled in water, and soaked therein until the whey is partly extracted and water is absorbed. The curd is drained, salted, stirred, and pressed into forms. A harmless preparation of enzymes of animal or plant origin capable of aiding in the curing or development of flavor of

added to .__ added

as a preservative," the blank being filled in with the common name or names of the mold-inhibiting ingredient or ingredients used.

(2) Wherever the name of the food appears on the label so conspicuously as to be easily seen under customary conditions of purchase, the statement specified in this section, showing the optional ingredient used, shall immediately and conspicuously precede or follow such name, without intervening written, printed, or graphic matter.

[24 F.R. 6481, Aug. 12, 1959, as amended at 25 F.R. 1016, Feb. 5, 1960, 27 F.R. 3005, Mar. 30, 1962, 28 F.R. 5420, June 1, 1963, 30 F.R. 1253, Feb. 5, 1965]

§ 19.507 Washed curd cheese for manufacturing; identity.

Washed curd cheese for manufacturing conforms to the definition and standard of identity prescribed for washed curd cheese by § 19.505, except that the milk is not pasteurized, curing is not required, and the provisions of paragraph (d) of that section do not apply. [24 F.R. 6481, Aug. 12, 1959]

§ 19.510 Colby cheese; identity; label statement of optional ingredients. (a) Colby cheese is the food prepared from milk and other ingredients specified in this section, by the procedure set forth in paragraph (b) of this section, or by another procedure which produces a finished cheese having the same physical and chemical properties as the cheese produced when the procedure set forth in paragraph (b) of this section is used. It contains not more than 40 percent of moisture, and its solids contain not less than 50 percent of milk fat, as determined by the methods prescribed in 19.500 (c). If the milk used is not pasteurized, the cheese so made is cured at a temperature of not less than 35° F. for not less than 60 days.

(b) Milk, which may be pasteurized or clarified or both, and which may be warmed, is subjected to the action of harmless lactic-acid-producing bacteria, present in such milk or added thereto. Harmless artificial coloring may be added. Sufficient rennet (with or without purified calcium chloride in a quantity not more than 0.02 percent, calculated as anhydrous calcium chloride, of the weight of the milk) is added to set the milk to a semisolid mass. The mass is so cut, stirred, and heated with continued stirring, as to promote and regulate the separation of whey and curd. A part of the whey is drained off, and the curd is cooled by adding water, the stirring being continued so as to prevent the pieces of curd from matting. The curd is drained, salted, stirred, further drained, and pressed into forms. A harmless preparation of enzymes of animal or plant origin capable of aiding in the curing or development of flavor of colby cheese may be added during the procedure, in such quantity that the weight of the solids of such preparation is not more than 0.1 percent of the weight of the milk used.

(c) For the purposes of this section: (1) The word "milk” means cow's milk, which may be adjusted by separating part of the fat therefrom or by adding thereto one or more of the following: Cream, skim milk, concentrated skim milk, nonfat dry milk, water, in a quantity sufficient to reconstitute any concentrated skim milk or nonfat dry milk used.

(2) Milk shall be deemed to have been pasteurized if it has been held at a temperature of not less than 143° F. for a period of not less than 30 minutes, or for a time and at a temperature equivalent thereto in phosphatase destruction. Colby cheese shall be deemed not to have been made from pasteurized milk if 0.25 gm. shows a phenol equivalent of more than 3 micrograms when tested by the method prescribed in § 19.500 (f).

(3) During the cheese-making process the milk may be treated as provided in § 19.500 (e) (3).

(d) Colby cheese in the form of slices or cuts in consumer-sized packages may contain an optional mold-inhibiting ingredient consisting of sorbic acid, potassium sorbate, sodium sorbate, or any combination of two or more of these, in an amount not to exceed 0.3 percent by weight, calculated as sorbic acid.

(2) Wherever the name of the food appears on the label so conspicuously as to be easily seen under customary conditions of purchase, the statement specified in this section, showing the optional ingredient used, shall immediately and conspicuously precede or follow such name, without intervening written, printed, or graphic matter.

[24 F.R. 6481, Aug. 12, 1959, as amended at 25 F.R. 1016, Feb. 5, 1960, 27 F.R. 3005, Mar. 30, 1962, 28 F.R. 5420, June 1, 1963, 30 F.R. 1253, Feb. 5, 1965]

§ 19.512 Colby cheese for manufacturing; identity.

Colby cheese for manufacturing conforms to the definition and standard of identity prescribed for colby cheese by

§ 19.510, except that the milk is not pasteurized, curing is not required, and the provisions of paragraph (d) of that section do not apply.

[24 F.R. 6481, Aug. 12, 1959]

§ 19.515

Cream cheese; identity; label statement of optional ingredients.

(a) Cream cheese is the soft uncured cheese prepared by the procedure set forth in paragraph (b) of this section. The finished cream cheese contains not less than 33 percent of milk fat and not more than 55 percent of moisture, as determined, respectively by the methods prescribed under "Fat-Official" on page 302 and under "Moisture-Official" on page 301 of "Official and Tentative Methods of Analysis of the Association of official Agricultural Chemists," Fifth Edition, 1940. (These methods appear in the 10th edition, 1965, p. 248, sec. 15.164; p. 247, sec. 15.157, respectively.)

(b) (1) Cream or a mixture of cream with one or more of the dairy ingredients specified in subparagraph (3) of this paragraph is pasteurized and may be homogenized.

To such cream or mix

ture harmless lactic-acid-producing bacteria, with or without rennet, are added, and it is held until it becomes coagulated. The coagulated mass may be warmed; it may be stirred; it is then drained. The curd may be pressed, chilled, worked, seasoned with salt; it may be heated, with or without added cream or one or more of the dairy ingredients specified in subparagraph (3) of this paragraph or both, until it becomes fluid, and it may then be homogenized or otherwise mixed.

(2) In the preparation of cream cheese, one or any mixture of two or more of the optional ingredients gum karaya, gum tragacanth, carob bean gum, guar gum, gelatin, algin, or propylene glycol alginate may be used; but the quantity of any such ingredient or mixture is such that the total weight of the solids contained therein is not more than 0.5 percent of the weight of the finished cream cheese.

(3) The dairy ingredients referred to in subparagraph (1) of this paragraph are milk, skim milk, concentrated milk, concentrated skim milk, and nonfat dry milk. If concentrated milk, concentrated skim milk, or nonfat dry milk is used, water may be added in a quantity not in excess of that removed when the milk or skim milk was concentrated or dried.

(4) For the purposes of this section, the term "milk" means sweet milk of cows, "skim milk" means milk from which the milk fat has been separated, and "concentrated skim milk" means skim milk from which a portion of the water has been removed by evaporation. (c) When an optional ingredient listed in paragraph (b)(2) of this section is present in cream cheese, the label shall bear the statement ". added" or "with added "the blank being

filled in with the word or words "vegetable gum," "gelatin," "algin," or "propylene glycol alginate," or any combination of two or more of these, as the case may be. Wherever the name "cream cheese" appears on the label so conspicuously as to be easily seen under customary conditions of purchase, the statement specified in this section, showing the optional ingredients present. shall immediately and conspicuously precede or follow such name, without intervening written, printed, or graphic matter.

[24 F.R. 6481, Aug. 12, 1959, as amended at 25 F.R. 8947, Sept. 17, 1960, 25 F.R. 10532, Nov. 3, 1960, 27 F.R. 3254, Apr. 5, 1962] § 19.520

Neufchatel cheese; identity; label statement of optional ingredients.

(a) Neufchatel cheese is the soft uncured cheese prepared by the procedure set forth in paragraph (b) of this section. The finished neufchatel cheese contains not less than 20 percent but less than 33 percent of milk fat and not more than 65 percent of moisture, as determined, respectively, by the methods prescribed under "Fat-Official" on page 302 and under "Moisture-Official" on page 301 of "Official and Tentative Methods of Analysis of the Association of Official Agricultural Chemists," Fifth Edition, 1940. (These methods appear in the 10th edition, 1965, p. 248, sec. 15.164; p. 247, sec. 15.157, respectively.)

(b) (1) Milk or a mixture of cream with one or more of the dairy ingredients specified in subparagraph (3) of this paragraph or a mixture of concentrated milk with milk or with water not in excess of that removed when the milk was concentrated is pasteurized and may be homogenized. To such milk or mixture harmless lactic-acid-producing bacteria, with or without rennet, are added and it is held until it becomes coagulated. The coagulated mass may be warmed; it may be stirred; it is then drained. The