Oct. 13
Oct. 14
Oct. 15

0

Fresh; stored sample had characteristic dried appearance...

1.79

1. 15

1.59

Per ct. 1.46

Per ct.

Per ct.

Per ct.

Per ct.

Per ct. Per ct. Per ct. Per ct.

1.20

1.51

1.02

0.88

0.98

11.45

7.61

10.21 9.34

7.94

9.69

6.53

5.82

6.29

1

All samples comparatively same; no signs of deterioration...

1.48

1.21

1.45

1.31

1.05

1.74

.96

1.03

.17

0.66

0.20

0

9.33

8.31

9.45

8.26 7.21

11.34

6.05 7.07

2 Samples beginning to deteriorate; more marked in fresh and stored; preserved, fairly fresh.

Oct. 16

3

Slight odor noticeable, more marked in fresh and stored; samples were spoiling and becoming soft.

1.85

1.65

1.91

1.61

1.38

1.46

1.98

1.52

1.69

.46

47

.28

11.81

10.70

12.23

10.28

8.95

9.35

12.64

9.86

10.82

2.94

3.05

1.79

Oct. 19

6

Odor quite bad and samples spoiled; were soft and "mushy"..

1.88

1.65

2. 13

1.46

1.38

1.77

3.16

2.61

2.38

1.20

1.23

.77

11.80

10.74

13.52

9.17

8.98

11.24

19.84

16.98

15.11

7.53

8.00

4.89

1.45 9.16

3.49 21.61

3.51 22.41

1.80

1.82

2.10

1.85

11.37

11.27

13.41

11.69

REPORT ON THE ADULTERATION OF DAIRY PRODUCTS.

By HERMANN C. LYTHGOE, Associate Referee.

The referee, with the help of Messrs. Nurenberg and Marsh, assistant analysts of the Massachusetts State board of health, has made a study of the different methods for the preparation of milk serum and for the detection of calcium sucrate in cream. As a result of this work it is apparent that the provisional method for the preparation of milk serum needs no modification, but the method of Baier and Neumann for the detection of sucrose in milk or cream should be made provisional. The work done is embodied in the two following articles.

A COMPARISON OF METHODS FOR THE PREPARATION OF MILK SERUM. The samples of milk used in this investigation were all milked in the presence of an inspector or an analyst of the Massachusetts State board of health and represented nearly all breeds of dairy cattle, particularly the Holstein, Ayrshire, Dutch Belted, and grade Holstein cows. The methods employed were the provisional (acetic acid) method, natural souring, a calcium chlorid method, and asaprol method. details of the methods other than the provisional methods are as follows:

The

Natural souring method.-Allow the samples to sour spontaneously and filter off the

serum.

Calcium chlorid method.-Place 90 cc of milk in a flask, add 0.75 cc of calcium chlorid solution-sp. gr. 1.1375 (when diluted 1:10 this solution reads 26 on the immersion refractometer at 17.6° C.), shake thoroughly, close the flask with a cork carrying a glass tube to act as a reflux condenser, place in a boiling water bath for twenty minutes, cool to 20°, mix the condensed water and serum without shaking, and filter.

Asaprol method. The precipitating solution is made by dissolving 30 grams of asaprol and 55.8 grams of crystallized citric acid in 1 liter of water. If the refraction of this solution is not 36.3 on the scale of the immersion refractometer at 20°, add water or citric acid to make it so. Mix equal volumes of the above solution and the milk, shake well, and filter.

In the accompanying table are the results of the refraction of the milk serum prepared from milk samples of known purity when two or more methods were applied to the same sample of milk. The asaprol method is by far the easiest of manipulation. It gives the clearest serum in the least time and shows the lowest refraction with the least variation. Unfortunately pure asaprol is very difficult to obtain, and, owing to the fact that it decomposes readily, it is not an easy matter to prepare different solutions that will give identical sera with the same sample of milk. The calcium chlorid method is the most difficult of manipulation and is liable to give a cloudy serum rather troublesome to read, but the results are lower than those obtained by the acetic acid method and not so variable. The natural souring method is too slow for ordinary use, but is valuable in the hot weather if the milk is nearly sour when it reaches the analyst. Four years' experience with the provisional method has shown it to be reliable, easy of manipulation, and to give concordant results.

a Matthes and Müller, Zts. öffentl. Chem., 1903, 10: 173.

Ackerman, Zts. Untersuch. Nahr. Genussm., 1907, 13: 186.

c Baier and Neumann, Zts. Untersuch. Nahr. Genussm., 1907, 13: 369.

Refraction of milk sera from known purity milk of individual cows.

THE DETECTION OF CALCIUM SUCRATE IN MILK OR CREAM.

The calcium sucrate used in this investigation was prepared by adding 2.5 parts, by weight, of sugar to 1 part of quick lime slaked in 8 parts of water, allowing to settle, and decanting the supernatant liquid. The sample polarized at 17.3° V. in the 200 mm tube and its alkalinity was 1.86 normal.

Leffmann's method for the detection of calcium sucrate in cream, using sesame oil and hydrochloric acid as the reagents, was found to be satisfactory only in the presence of larger quantities than are necessary to thicken cream, therefore it was abandoned. The method of Baier and Neumannb was found to be entirely satisfactory for the detection of sugar, and is as follows:

a Chem. Ztg., 1906, 30: 638.

bZts. Nahr. Genussm., 1908, 16: 51.

To 25 cc of milk or cream add 10 cc of a 5 per cent solution of uranium acetate, shake, allow to stand for five minutes and filter. If the filtrate is not clear pour it through the filter again. To 10 cc of the clear filtrate (in the case of cream use the total filtrate if less than 10 cc) add 2 cc of a cold saturated solution of ammonium molybdate and 8 cc of dilute hydrochloric acid (1 part of 25 per cent hydrochloric acid and 7 parts of water) shake well and place in a water bath at 80° C. for five minutes. If the sample is pure the solution will resemble a nickel sulphate solution, but if sugar is present it will be of a Prussian blue color. These different colors can be readily distinguished but it is advisable to compare with a standard blue solution made by adding a few drops of potassium ferrocyanid and 5 drops of 10 per cent hydrochloric acid to a solution of 1 cc of 0.1 per cent ferric chlorid in 20 cc of water.

Alkalinity of ash.-Evaporate 25 cc of cream to dryness, and burn to an ash in a muffle. Dissolve the ash in an excess of tenth-normal sulphuric acid, boil to expel the carbon dioxid and titrate back with tenth-normal sodium hydroxid, using phenolphthalein as the indicator. Express results as cubic centimeters of tenth-normal acid required to neutralize the ash of 100 grams of cream.

Determination of calcium.-Add acetic acid to the final solution from the above determination, heat to boiling, add 1 gram of sodium acetate and an excess of ammonium oxalate. Filter and wash the precipitated calcium oxalate with water, dissolve in hot dilute sulphuric acid, and titrate hot with tenth-normal potassium permanganate. The number of cubic centimeters of tenth-normal potassium permanganate multiplied by 0.0112 (4 × 0.0028) gives the percentage of calcium oxid in the sample. The table appended shows the composition and reactions of pure and adulterated cream, using the Baier and Neumann method for calcium sucrate. It is recommended that this method be distributed for criticism.

Results on pure and adulterated creams using the Baier and Neumann method for calcium

During the past year considerable work was undertaken in our own laboratory upon cereal products, very little of which has as yet been completed. Therefore only a report of progress can be made. As the result of examinations made by A. S. Mitchell, chief of the St. Paul Food and Drug Inspection Laboratory, the following methods are suggested:

METHODS FOR ANALYSIS OF CEREAL PRODUCTS.

MOISTURE.

Dry a convenient quantity of the flour (approximately 5 grams) at the temperature of boiling water in a current of dry hydrogen or in vacuo until it ceases to lose weight.