6 TOMATO KETCHUP UNDER THE MICROSCOPE. 



As regards the limits which may be expected in the examination 

 of ketchups for bacteria, it might be stated that some manufactured 

 samples as well as good, clean products made by household methods, 

 have been examined and the count found to be so low when esti- 

 mated by this method that the numbers present were reported as 

 negligible. In other words, it was found that for the areas counted 

 over the number of bacteria averaged less than one that is, less than 

 2,400,000 per cubic centimeter. It is unusual, however, for the final 

 number per cubic centimeter to be less than from 2,000,000 to 

 10,000,000 organisms. Contrasted with this number as a minimum, 

 it has been found that the number has occasionally exceeded 300.- 

 000,000 per cubic centimeter. Such a number as this would indicate 

 extremely bad conditions and carelessness in handling, as the studies 

 of factory conditions has shown that there is little excuse for the 

 number ever exceeding 25,000,000 per cubic centimeter. While ex- 

 periments have also shown that although the effect produced by the 

 bacteria on the product varies with different species, it is true that 

 their presence can frequently be detected in the raw pulp by odor 

 or taste when the number exceeds 25,000,000 per cubic centimeter and 

 sometimes when the count is as low as 10,000,000. 



To one who has not been initiated into the mysteries of the micro- 

 scope the presence of such a number of bacteria in a food product 

 seems inexcusable. It must be remembered in this connection that the 

 most of these are probably nonpathogenic forms, and many occur 

 naturally on the skins of the -fruits. It does not seem just to set a 

 standard so high as to virtually prohibit the manufacture of the 

 product under commercial conditions; rather the idea is to set a 

 limit that the manufacturer can attain if due care is exercised and 

 which will insure a cleanly product. It is, however, perfectly pos- 

 sible to make a cleanly, wholesome product commercially even 

 though the number of bacteria exceed that in the homemade article. 



The allowable limits for the bacterial content of tomato pulp vary 

 according to the concentration. The number, however, should be 

 low enough so that when the amount of concentrating necessary for 

 its conversion into ketchup has been accomplished the final product 

 will still be within permissible limits (25,000,000 per cubic centi- 

 meter). Thus for a pulp which must be concentrated one-half the 

 bacterial counts should not exceed about half the limits stated above 

 for the ketchup itself i. e. ? it should not be more than 12,500,000 per 

 cubic centimeter. The same general rule should also apply to the 

 content of molds and of yeasts. 



To insure a sound product, free from decay or any filthy material, 

 many factors must be carefully watched, for not infrequently over- 

 sight in one particular has been found to have undone the good effects 



