IX. METHODS FOE THE ANALYSIS OF CANNED VEGETABLES. 



PROVISIONAL. 



1. Physical Examination. 



A careful examination of this character is often of material value in detecting 

 inferior quality with certain classes of vegetables. Upon opening a can, care- 

 fully 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. 

 In the case of mushrooms and capers no further examination is necessary, as a 

 rule, except the detection of sulphites in the former and copper in the latter. 



The most common species of mushrooms found upon the market is Agaricus 

 campestris, although different varieties of Boletus are occasionally found. The 

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

 state, are seldom free from them. These larvae 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 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 by general appearance and by taste. Gherkins and 

 mixed pickles, while not strictly included in this class of foods, are considered 

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

 largely macroscopically and by taste. Copper is sometimes used to produce a 

 bright green color. When mustard is used with mixed pickles, turmeric is 

 frequently added as a coloring agent It is also advisable to test for anil in 

 dyes if turmeric is not detected. 



2. Preparation of the Sample. 



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 estimate the percentage of liquid and solid contents. Then thoroughly 

 grind the entire contents of the can either in a mortar or by means of a food 

 chopper; mix thoroughly and preserve in a glass-stoppered bottle for analysis. 

 Unless the analysis is to be completed within a reasonably short time, it is 

 best to dry the entire sample after the determination of moisture is made. 



After thorough drying, expose the material to the air for several hours, or 

 until it becomes air dry. A second moisture determination is necessary with 

 this procedure. 



3. Total and Volatile Acids. 



It is occasionally desirable to determine total acids in tomatoes and catsups, 



and volatile acids in the latter. For this purpose use the methods described 



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