CANNING SARDINES 95 
Organisms (bacteria, molds, and yeasts) act upon oils and give 
rise to changes in their composition, the main change being an in- 
crease in acidity. The enzyme lipase occurs in the seeds of many 
plants and in some animals. It acts on oils (in the presence of 
moisture), splitting them into free fatty acids and glycerin. 
On exposure to air oils are oxidized, giving rise to a number of 
changes. The most important one is the development of a rancid 
taste and odor. Some oils thicken and eventually become solid; 
this takes place in air and is called drying. Sardine oil exhibits this 
phenomenon. 
Light and heat produce polymerization of the fats (visually indi- 
cated by thickening of the oil). They accelerate the action of mois- 
ture on oils, giving rise to increased acidity. Oxidation changes are 
similarly accelerated. 
Rancidity in oils may be looked upon as being due to the formation 
of free fatty acids by enzymes in the presence of water and the sub- 
sequent action of oxygen and light on the free fatty acids. Fats and 
oils kept fully protected from light, air, and moisture will keep in- 
definitely in their original condition. 
Sardine canners have used methods of one nature or another in 
an endeavor to improve their oil during use. These efforts usually 
have been of a mechanical nature—washing with water and filter 
pressing or centrifuging. At times fuller’s earth and other similar 
substances have been used on the oil. It is safe to say that none of 
these methods (although all are helpful) have been very successful. 
Chemical methods of recovering used oil have been tried but they 
have been found to be expensive and unsatisfactory. 
Discussion with canners elicited many conflicting suggestions as to 
the nature and causes of the changes that take place in frying oil. 
It was generally believed, however, that more or less fish oil gets 
into the cottonseed oil and causes trouble. 
This lack of knowledge made it clear that in studying the problem 
it would first be necessary to determine the exact nature of the 
changes that take place in the oil and the factors that contribute 
thereto. With such information at hand, the problem would resolve 
itself into a study of means to eliminate the objectionable factors, if 
possible, or to devise a better method of accomplishing the same 
end. This was the path followed. 
EXPERIMENTS 
FRYING 
Two runs of frying tests were carried out in order to obtain accurate 
information concerning the changes that take place in oil used for 
frying sardines. Each run consisted of tests on two lots of oil. 
The equipment used in these tests consisted of two small vats, 
or fry baths, as they are usually called, 1434 by 101% by 934 inches, 
inside dimensions, with steam coils midway of their depth. 
Procedure and data, first run.—Large, fat, California pilchards were 
prepared for frying by being scaled, headed, and eviscerated, then 
dried for 60 minutes in air having a velocity of about 500 feet per 
minute and a temperature around 100°. Most of the fish were brined 
45 minutes in an 85 per cent saturated salt solution before being 
