Issued February 18, 1911. 



United States Department of Agriculture, 



BUREAU OF CHEMISTRY CIRCULAR NO. 68. 

 H. W. WILEY, Chief of Bureau. 



TOMATO KETCHUP UNDER THE MICROSCOPE; 



WITH PRACTICAL SUGGESTIONS TO INSURE A CLEANLY PRODUCT. 



By B. J. HOWARD, 

 Chief, Microchemical Laboratory. 



INTRODUCTION. 



The various products manufactured from tomatoes are becoming 

 more and more important commercially from year to year. Those 

 who have watched the industry during the past 5 or 10 years have 

 noted radical changes in some of the manufacturing methods which 

 tend to produce a cleaner and more wholesome product. Especially 

 is this true of the manufacture of ketchup. Some manufacturers, 

 however, are still producing their product under conditions which show 

 a lamentable lack of care, and are making themselves liable to prosecu- 

 tion and their products to condemnation. It is, however, the writer's 

 opinion that much of this is the result of ignorance as to the influence 

 that certain methods of handling exert upon the character of the 

 product. It is for the purpose of giving the manufacturer the benefit 

 of certain practical results of laboratory and factory investigations 

 of the various methods of handling these products that this circular 

 is written. It is not intended to deal with the subject exhaustively, 

 nor to present the detailed micro-analytical data on which the con- 

 clusions are based, but rather to give the practical deductions of the 

 investigations and the reasons for the same in a manner that will be 

 clear to the manufacturer, who may not have a technical education. 

 To this end some points which may be used to advantage by those 

 engaged in the manufacture of such products will be emphasized 

 and some of the pitfalls which beset the manufacturer indicated. 



NATURE OF DECAY. 



Under the food and drugs act, June 30, 1906, a food product is 

 deemed to be adulterated " if it consist in whole or in part of a 



74671 Cir. 6811 



