TOMATO KETCHUP UNDER THE MICROSCOPE. 13 



gas held in the fibrous portions. The lower stratum contains a 

 considerable proportion of the water from the fruit, together with 

 some of the soluble solids, while the top contains more or less water 

 and the insoluble portions, which consist largely of the cellular mate- 

 rial. By careful manipulation it is possible to draw off half or two- 

 thirds of the original volume in the lower layer, and some have 

 supposed that they were removing nothing but the water by this 

 operation, but the facts are quite to the contrary, as the water which 

 is removed is as rich in the natural sugar and acid of the fruit and 

 flavoring material as that remaining in the pulp. 



A simple test of this loss can be made by placing some of the 

 " water " in a suitable dish and boiling it down to about one-fourth 

 of the original volume. The resulting product will be found to be 

 especially rich in tomato flavor. Thus it is seen that the gravity 

 method is an extremely wasteful one. Though this method of con- 

 centrating is cheaper than by boiling, this is about the only thing 

 that can be said in its defense. Some claim that the product is sub- 

 jected to heat for a shorter time by this treatment, and therefore it 

 retains a better color; but with a proper arrangement of kettles hav- 

 ing a good head of steam (80 pounds or more) the concentrating 

 of the entire pulp to the consistency of ketchup can be accomplished 

 in from 40 to 50 minutes, which is as short a time as is safe if even 

 an approximately sterile product is to be obtained. 



It was found that 9 per cent of the factories that were making 

 ketchup from whole tomatoes were using the gravity method of con- 

 centrating. Of those that were making trimming pulp, 78 per cent 

 used this method. Frequently manufacturers who make both whole 

 tomato ketchup and also a trimming pulp grade use the entire juice 

 method for the whole pulp and the gravity method on the trimming 

 pulp. 



At some plants it is customary to process the ketchup after bottling, 

 while others find it unnecessary. The formula and amount of con- 

 centration are probably largely responsible for this difference, as well 

 as for the varying temperatures at which the product is bottled. 



STORING. 



While some factories do not make up all of the pulp during the 

 packing season many are doing this both because of the superior 

 product obtained and because of the difficulty of keeping the stored 

 pulp in good condition. Many of the canning factories simply make 

 the pulp and sell it to the final manufacturer. The proper storing 

 of the pulp is an important problem, since if it is not properly 

 handled, spoilage will set in, offsetting any previous care which had 

 been taken to produce a good product. The pulp is usually stored 



