EXAMINATION OF CANNED PRODUCTS old 
former times, many unscrupulous manufacturers used spoiled fruit, 
and by-products from the tomato canning industry for making ketchup 
Satisfactory methods for separating good and bad ketchups have been 
hard to find. In general, a bad or low-grade ketchup 1s one which has 
been made from decayed or partly decayed fruit. The methods which 
are now used are microscopical and center around determining the num-~ 
bers of bacteria, yeasts and molds. Bitting (1909) used superficial 
methods for studying spoilage of tomato ketchup. He found that 
ketchup prepared from whole ripe stock had a low content of microor- 
ganisms and in that prepared from decayed fruit large numbeis of micro- 
organisms were present. 
Howard (1911) proposed a method for the examination of ketchup 
which has been in use since then probably because no one has proposed 
a better one to 1eplace it. This method is based on cxamuning the 
tomato product for yeasts, molds and bacteria, and it 1s thus assumed 
that these microorganisms indicate that decayed fruit was used or that 
the method of manufacture is faulty. This latter possibility was found 
to be the case in an instance quoted by Howard (1917). A manufac- 
turer was using ripe fresh tomatoes and still secured high counts in the 
final product. 
Howarp’s Mertruop ror tHe MICROANALYSIS OF Tomato PRopuUCcTS 
AND INTERPRETATION OF THE RESULTS 
Apparatus Required. The outfit used is as follows: 
A good compound microscope giving magnifications of approyi-~ 
mately 90, 180, and 500 diameters. This 1s accomplished by the use 
of a 16 mm. (two-thirds of an inch) objective and an 8 mm. (one-third 
of an inch) objective, together with a medium (6 compensating) and 
also a high-power ocular (X18 compensating). A Thoma-Zeiss blood- 
counting cell,* a 50-c.c. graduated cylinder, and ordinary slides and 
cover glasses complete the apparatus required. It is impractical to 
use objectives of a higher power than those mentioned, because of their 
short working distance, which makes their use with the counting cell 
inpossible. 
Estimation of Molds. A drop of the product to be examined is 
placed on a microscope slide and a cover glass is placed over it and 
* This 1s a cell named after the designer of the form of rulings used, and consists 
of a slide with a disk ruled in 3; mm squares, so arranged that when the cover 1s 
in place the film of hquid under examination 1s 4; mm deep They were originally 
intended for counting corpuscles in the blood and are obtainable from practically 
all manufacturers of microscopic accessories. 
