164 ti. 8. BUREAU OF FISHERIES 
TABLE 18.—Changes in oil content of fat California pilchards in frying 1 





— Weight 
Sample Weight, | Per cent | Per cent | of fat 
: gQrams | moisture fat in fish, 
grams 
Before trying 662 - — Mesea Sie eee Ee ee ee ee 1, 263 60. 9 11.:2)| 3465 
Attenirying = <2... sto sedi Deepest ee cc 1, 167 58. 2 13.6 | 158.7 
@ilossifrom wpath to fishy 2 oie es ee Se ee ee eee eS oe 17.2 
Oililess from bath ‘to fish: per units offish frieds= = 2-  e e  eeeeee 0. 0136 


1In preparing the fish for frying, 20 fish, weighing 4,210 grams, lost 37.9 per cent in weight in being 
butchered, 0.1 in brining, and 3.3 in drying, calculated on the original weight. On the same basis the loss 
in frying in 10 fish which were fried was 4.4 per cent. 
In this experiment the oil removed from the bath per unit of fish fried was 
0.0136 (0.0136 gram per gram of fish fried). These fish were not allowed to 
drain 8 minutes over the bath, as was done in the experiment with lean fish 
(Table 17). Had they been allowed to drain, undoubtedly as much oil (and 
probably more, since the fish were very fat) would have drained from them as 
did from the lean fish (0.015 unit of oil per unit of fish fried). Such fish as these 
would give up a little more oil than they remove, thus causing the oil in the bath 
to increase with use. Pure cottonseed oil (1,475 grams) was used for frying the 
1,263 grams of fish. After frying there remained approximately 1,458 grams 
of oil (1,475 grams minus 17 grams carried out by the fish). The sardine-oil 
content of this oil was determined by caiculation from the iodine numbers of 
pure sardine and cottonseed oils and the mixed oil after frying. The sample of 
sardine oil analyzed was obtained from fat fish by boiling them in brine. Deter- 
minations were made by the Hanus method. Scott“ describes this method and 
the method of calculation used in determining the sardine-oil content. The 
results of this determination, given in Table 19, show that the cottonseed oil 
after frying, contained 4 per cent, or 58.3 grams, of sardine oil. This gives a 
loss of at least 0.046 unit of sardine oil from the fish to the bath for each unit 
fried. The loss was more, however, because some sardine oil was removed as a 
part of the mixed oil carried out of the bath by the cooked fish. Oxidation of 
the oil during the heating period tended to lower the iodine number of the mixed 
oil, and this in turn tended to lower the calculated amount of sardine oil. This 
tendency, however, was small, the oils being heated, in all, less than 1 hour. 
TaBLE 19.—Fish-oil content of cottonseed oil used in frying one lot of large, fat 
California pilchards } 

Iodine number - 


Oil 
1 2 Average 
Sardine=t =) 2322 seek Sle sae NE es ee eee 160. 0 160.0 160. 0 
@ottouseed, before: frying: ys. 2-54. 2 Sense oie eee ee ee eee 107.5 107.0 107. 2 
Wottensced arid sardine; iaiter frying. = 255 ee oe ie a ee 109. 5 109. 2 109. 3 _ 
1 1,263 grams fish fried in 1,475 grams of oil—1,458 grams left after frying. 
100 (109.3 — 107.2 é ; 
Calculation: es 107.2 = per cent sardine oil. 

It has been shown experimentally that a sample of large, lean fish, which would 
give up no oil in the fry bath, removed about 0.035 unit of oil from the bath for 
each unit of fish fried 8 minutes in oil at 230° and allowed to drain over the oil 
in the bath for 8 minutes. It is very probable that large, fat fish fried in the same 
manner would mechanically carry out of the bath an equal quantity of oil. If 
this is true, and if it is assumed that the oil content of the bath remains constant, 
then 0.035 unit of oil must cook out of the fish per unit fried. Oil does cook 
out of the fish and mix with the oil in the bath, for it has just been shown that 

a prandard Methods of Chemical Analysis. By Wilfred W. Scott. 3d ed., vol. 2, pp. 1128-1130. New 
ork, 1922, 
