496 FOOD PRESERVATION 
unnecessary contamination during production. In this connection, it 
should be remembered that many foods contain bacteria in the tissue. 
This has been shown in other places in this book. Hoagland, McBryde 
and Powick (1917) found a micrococcus to be normally present within 
the tissues of fresh beef. Bacteria have also been found in tissues from 
other sources. 
The relation of environmental conditions during production to 
infection of foods needs no extended discussion. Many cases of food 
poisoning from meats have been traced back to infection during slaugh- 
ter. Other factors tend to render the aseptic production of meat im- 
practicable and impossible. Certified milk is the nearest approach to 
the production of aseptic milk. Water glass is used for preservation of 
ego's and this is probably a good example of aseptic preservation of foods. 
The humidity of the atmosphere in which foods are kept, is an im- 
portant determining factor. Water is necessary to carry food into the 
cell and remove the waste products from the cells of microorganisms. 
Spores will not germinate if there is insufficient moisture present. 
The physical structure of the food may determine the type of 
decomposition. Nature has provided many foods with efficient bar- 
riers against the attack of microorganisms. Unless these are broken in 
some way, the microorganisms are not able to accomplish any damage. 
Fruits, such as apples, cherries, pears, etc., are provided with a thick 
cellulose skin which is very resistant to the attack of microorganisms. 
Few of them possess a cellulase with which to attack this barrier. Eggs 
are protected by a shell which is covered with a gelatinous layer. If 
this is removed by washing, the egg will spoil much more quickly. 
In general, the conditions under which a food is produced greatly 
influence any method that may be adopted to preserve it. 
Spices. Condiments have probably been a little over-emphasized 
as food preservatives. Bitting (1909), in studying the preserving 
action of spices in ketchup found that cinnamon and cloves were the 
strongest antiseptics. He boiled 20 gms. of the whole spice in 200 c.c. 
of water for forty-five minutes. This was then filtered and from 0.1 
to 5 c.c. of the filtrate added to tomato bouillon. Mustard, paprika 
and cayenne pepper checked growth, but 5 c.c. of the highest strength 
did not inhibit growth. Bachmann (1916), using different technique, 
secured somewhat the same results. Using the oils, she found that 
cinnamic aldehyde was most effective in preventing the growth of all 
organisms studied. Eugenol and oil ot allspice had a distinct preserv- 
ative action. Molds were found to be more sensitive than the bac- 
teria or yeasts. 
