50 PROVISIONAL METHODS FOR ANALYSIS OF FOODS. 



plate in a funnel to separate from particles of the inclosing shell, and ascertain the 

 weight of the sirup. Dilute with half its volume of water and determine alcohol as 

 directed on page 82. 



15. DETECTION OF COLORING MATTER. 

 Proceed as directed under Coloring matters (p. Ill and following). 



VII. CANNED VEGETABLES. 



By L. S. MUNSON, 

 Bureau of Chemistry, U. 8. Department of Agriculture. 



1. GENERAL DISCUSSION. 



In the investigation of canned vegetables, the proximate analysis is, as a rule, of 

 little value in determining quality; much more depends upon the size, age, and 

 fresh and healthy condition of the vegetables at the time of canning, and the treat- 

 ment during and subsequent to the processes of canning. Hence, methods for the 

 proximate analysis have been given minor consideration to means of determining 

 the quality of the various classes of vegetables and the detection of different forms 

 of adulterants. Much still remains to be done with this class of food, as the time at 

 the disposal of the writer was not sufficient to investigate thoroughly the various 

 problems that presented themselves. 



2. MACROSCOPIC EXAMINATION. 



A careful macroscopic examination is often of material value in detecting inferior 

 quality with certain classes of vegetables. Upon opening a can, carefully note the 

 appearance of the contents as to quality, color, and size. Any undue corrosion, or 

 blackening of the walls of the can, should also be observed. With mushrooms and 

 capers, no further examination is necessary, as a rule, except the detection of sul- 

 phites in the former. 



The most common form of mushrooms found upon the market is Agaricus cam- 

 pestris, although different varieties of Boletus are occasionally found. The latter are 

 particularly susceptible to attack by larvae and, except in a fresh state, are seldom 

 free from them. These larva? may readily be seen with the naked eye, or by use of 

 a small hand lens. Many of the mushrooms on the market are of inferior quality, 

 and consist largely of old and broken fragments of tops and stems; occasionally 

 diseased fungi are to be found in the inferior grades. Owing to the nature of this 

 vegetable, only the fresh, healthy specimens should be passed as edible. 



Capers are the liower buds of Cappares spinosa and, so far as known, are but little 

 liable to adulteration. Owing to their green color, it is always advisable to make 

 a qualitative test for copper. 



Olives are to be judged entirely by general appearance and by taste. Gherkins 

 and mixed pickles, while not strictly under this class of foods, are considered here 

 along with olives for the sake of completeness; these also are to be judged largely 

 macroscopically and by taste. The use of copper with this class is of frequent 

 occurrence to produce the bright green color; with mixed pickles, where mustard is 

 used, turmeric is frequently added as a coloring agent. It is also advisable to test 

 for aniline dyes where turmeric is not detected. 



3. PREPARATION OF THE SAMPLED 



Weigh the full can; open, pour off the liquid portion, and reweigh the can; then 

 empty out the solid contents of the can and weigh again. From these weights esti- 

 mate the percentage of liquid and solid contents. By this means, any undue propor- 



U. S. Dept. of Agr., Div. of Chem., Bui. 13, pt. 8, p. 1027. 



