12 TOMATO KETCHUP UNDER THE MICROSCOPE. 



way the fresh pulp is run in with some that may have been in the 

 tank for several hours, and the fact that the tank is not com- 

 pletely emptied and cleaned out from morning till night allows 

 spoilage to begin, and some injury to the product is done. A better 

 way is to have a set of smaller vats, if the pulp is to be stored at all, 

 so that each vat as it is emptied can be cleaned out before a new 

 lot is run in, thus checking any fermentation that might result due 

 to the storing of the pulp in the same vat throughout the day's run. 



One serious criticism to be made of the gravity method of concen- 

 trating as practiced by some factories is the length of time that the 

 product stands before being cooked up into the final product. This 

 was found to vary in different factories from 30 minutes to half a day 

 or more. A few did not leave a batch standing more than 30 minutes 

 after the last of it had been run in, but by that time the first that had 

 gone into the vat had usually been standing from one and one-half to 

 two hours. Even this length of time allows a large number of or- 

 ganisms to develop, and it makes little or no difference in the final 

 product where the decay occurs, whether in trimmings from the 

 tables, in the vats after chopping (if that is practiced), or in the 

 pulp in the vats before it is worked up. As soon as the fruit is 

 peeled it is imperative that the trimmings should be worked up with 

 the least delay possible, for it has been shown that spoilage takes 

 place rapidly after the tomato tissues are torn. 



Although this applies especially to the handling of trimmings, it 

 is equally true of the whole tomato pulp. And furthermore, to 

 expect that the results of carelessness in handling the pulp stock can 

 be removed by subsequent cooking is a serious mistake, for though 

 the product will be sterilized by sufficient cooking, the dead organisms 

 that produced the decay remain in the ketchup, as well as some of 

 their products of decomposition, and a marked deterioration in the 

 character of the final product necessarily results. 



CONCENTRATING. 



The tomato pulp, as it comes from the pulper, contains the fibrous 

 cellular material of the fruit, and also the " water " or, more prop- 

 erly, the juice of the tomato. The cellular material is insoluble in 

 water and corresponds to the residue remaining after cider has 

 been squeezed from apple pulp. In the juice or " water " are con- 

 tained the most of those products which give to the tomato its 

 characteristic taste and flavor. Among these are certain fruit acids 

 and sugars without which the product has a flat taste. 



The pulp obtained from the fruit in making ketchup is usually 

 concentrated, by boiling or otherwise, to about 50 or 25 per cent 

 of the original volume. Finely chopped tomatoes or tomato pulp 

 on standing separates into two portions, due to small amounts of 



