80 BULLETIN 908, U. S. DEPARTMENT OF AGRICULTURE. 
water present in the fish and to the number of times the packed goods 
are frozen. Mustard sardines, however, are very seriously damaged 
by freezing and thawing, even once, particularly if improperly dried © 
before packing. The texture of the flesh is destroyed, the appear- 
ance injured, and the tasie lost. 
The desirability of storing sardines at a low, even Epes was 
demonstrated by these experiments. 
DETINNING OF SARDINE CANS. 
EFFECT OF SULPHUR IN SKIN OF FISH. 
More or less blackening or detinning of the inner surface of the 
unlacquered sardine cans always occurs on standing. It was sug- 
gested by a former packer that this might be due to the action of 
some compound in the skin of the fish, as from his experience skinned 
fish when packed did not cause detinning. Sulphur was first con- 
sidered as a possible cause of the detinning. A difference in the quan- 
tity of sulphur in the skin of the fish and in the flesh, provided the 
skinned fish did not attack the tin, would indicate that sulphur was 
an important factor in this phenomenon. 
A small pack was made of skinned and unskinned fish from the 
same source which had been the same length of time in pickle. 
Part of the fish were skinned and then steamed, dried, and packed. 
The other portion was dried and packed without removing the skin. 
- Both lots were packed in oil at the rate of less than 2 gallon per case, 
and were sterilized for 1? hours m a boiling water bath. In all re- 
spects, except for the skinning of part of the fish, the packs repre- 
sented actual commercial conditions. Representative samples of the 
skin and flesh of the fish composing this pack were analyzed, with 
the results shown in Tabie 34. 
TABLE 34.—Composition of skin and flesh ef sardines. 
Determination. 3 Skin. | - Flesh. 
Per cent. | Per ceni. 
W ECT ae oe Sn do Soc oes SSR Sere ce Se oO rn ee ee See See ee ee 63. 60 70. 76 
abe erat ee Serer Bee SE SO a i ee 9 ee ge eee 14. 62 3. 56 
Total BEREF OCHRE CN) oS 2S ea ge eg eee ee eee 2. 85 3. 90 
Prnkcid @NE<G:25) £2 se Te Oe ee ee eee 17. 81 24. 38 
Dali CNAs fae 2 a re ge Seem ee eee age 4.05 1.79 
otalsulphur(S). 2. ELS RR A RS Se ee ee ee 0. 207 0. 260 
LotaLsuiphurCwater and fat free basis) ss #5 be eee ee ee ee 0.95 1.01 
Total sulphur (water, ae and salt free basis) uD SAE ET RES SS ie Se i 2 ees TEC 1.09 
The amount of sulphur in the skin was practically the same as that 
in the flesh of these fish. A marked difference in the extent of de- 
tinning between cans packed with the skinned and those packed with 
the unskinned fish would not, then, be due to the quantity of sulphur — 
present, aithough it might be due to its form of combination. No 
work, however, was done to determine the form in which sulphur 
