2 TOMATO KETCHUP UNDER THE MICROSCOPE. 



filthy, decomposed, or putrid animal or vegetable substance." Decay 

 or putrefaction in tomatoes is commonly the result of the attacks 

 made by various forms of plant life upon the fruit or upon the par- 

 tially manufactured product. Among these, yeasts, bacteria, and 

 molds of various species are the most common. They feed upon 

 certain compounds in the tomato, reducing the food value of the 

 product, producing by-products of a more or less offensive character, 

 and usually modifying the characteristic flavor of the product. They 

 may attack the fruit on the vine before picking or at almost any of 

 the various steps of manufacture, and if the conditions for preserva- 

 tion are not right they may infect and cause spoilage in the finished 

 product. Among the forms most liable to attack the fruit on the 

 vines are some species of molds. One of the most familiar molds, 

 both to the farmer and to the manufacturer, results in the produc- 

 tion of " dry " or " black rot." Some others appear as white growths 

 on the fruits and usually develop after the fruit has been taken 

 from the vines, entering through cracks or fissures in the skin of the 

 fruit. This also occurs in the entrance and growth of yeasts and 

 bacteria. If the temperature conditions are favorable the develop- 

 ment of yeast and bacteria in the raw flesh of the tomato or in the 

 raw partially manufactured product is very rapid and the rate of 

 growth increases tremendously when the hosts are stored in close, warm 

 quarters. Good ventilation tends on the other hand to retard such 

 growth. The decomposition products due to these organisms appear 

 to be much the same whether the growth occurs on the whole fruit, 

 in the pulp, or in the stored product. Boiling may arrest the growth 

 for a few hours, but if the product is not shielded from fresh infec- 

 tion, the benefit thus derived is only temporary, for it is the common 

 knowledge of many manufacturers that tomato pulp will keep only 

 a short time, even after prolonged heating, unless it is stored in 

 well-sealed packages of some sort. It is at this point that some 

 manufacturers have failed because, although the raw materials may 

 have been fairly free from decayed or putrid material, they have 

 handled it in such a way as to allow decomposition to occur at some 

 of the various stages of manufacture. As a general rule it seems 

 that the decay for which molds are largely responsible appears in the 

 fruit before the actual manufacturing processes are begun, that is on 

 the vines, or in the crates after picking, while those forms in which 

 yeasts and bacteria play the principal role appear in greatest num- 

 bers at some stage after the manufacture has begun. Therefore it 

 is seen that a product may be subject to criticism when the trouble 

 is almost wholly due to molds present on the raw fruit. This is 

 particularly true of much of the product made up at once during 

 the packing season from trimming materials which have not been 

 stored for a sufficient length of time for other forms of decomposition 



