3 cc. of 15 percent sodium hydroxide and 15 cc. of the isobutyl alco- 

 hol were added. These were shaken vigorously for 1 1/2 minutes. The 

 tubes were centrifuged for 1 minute and the aqueous layer siphoned 

 off. Two to three grams of anhydrous sodium sulphate were added, 

 thoroughly mixed, and the tubes were again centrifuged. The clear sol- 

 ution vras decanted into cuvettes to be read irawediately in the previous- 

 ly adjusted Coleman photofluorometer. For standardization, the instru- 

 ment was set to read 70 with a 0.3 mg. per liter quinine sulphate solu- 

 tion. The instrument was checked with the quinine sulphate solution 

 before each sample vgas read. The following formula was used to determine 

 the thiamine content: 



Sample Micrograms 



reading - Blank x 1 x 25 x 100 - per 



Standard 5 Vol.decalsoed Wt.of Sample Gram 

 reading - Blank 



Recovery samples were rtin on the various types of products by adding 

 a definite amount of thiamine to a sample and running the regular assay. 

 Recovery assays with the raw materials and fish meals were high enough 

 to indicate that there was no significant destruction of the thiamine 

 during the extraction process. Frcm 95 to 105 percent of the thiamine 

 added was usually recovered. 



Proximate Analyses 



Proximate analyses were run to obtain the moisture, ash, protein and 

 oil content of the raw materials and fish meals. These deteiuiinations 

 were made by standard A.O.A.C. procedures. 



Results and Discussion 



The resiilts of the vitamin and proximate analyses are given in Table 

 I. Since the components of the diets prepared for the feeding tests are 

 added to the diets on a wet basis, the vitamin analyses are also report- 

 ed on a wet basis. 



The stickwater concentrate was the liquor formed during the prepara- 

 tion of the air-dried Alaska pink viscera meal. Since the stickwater con- 

 centrate has a high vitamin content, the loss of vitamins during the pro- 

 cessing of the meals seem to be due to the solution of the vitamins 

 rather than to their destruction. 



There was very little difference between the vitamin content of the 

 fish meals dried at 145° F. and those dried at 100°F. However, the flame- 

 dried meal prepared canmercially had a sigiificantly lower vitamin con- 

 tent than these air-dried meals. 



85 



