BIOTIN CONTENT OF MEAT AND MEAT PRODUCTS 1 The biotin ...

66 B. S. SCHWEIGERT AND OTHERS
4 or 6 normal H2S04 for 2 hours gave maximum liberation,
while longer periods of autoclaving resulted in considerable
destruction of the biotin. The procedure adopted for libera
tion of biotin was a 2-hour autoclaving of the sample in 6N
H2S04. This procedure was used for all samples analyzed.
Satisfactory recoveries of added biotin were obtained when
this procedure was used.
After treating the samples with 6N H,S04, the digestion
mixture was neutralized with NaOH. It was necessary to
determine whether the Na2S04 formed would act as a stimulant
or an inhibitor of Lactobacillus casei. The maximum amount
of Na2S04 present in any assay tube was 0.7% and it was
found that Na2S04 concentrations ranging from 0.2-1.8%
had no effect on the assay.
Meat samples 45-257 have been previously analyzed for
their vitamin content (Waisman and Elvehjem, '41 ; Mclntire,
Schweigert, Henderson and Elvehjem, '43; and Schweigert,
Mclntire and Elvehjem, '43). Samples 45-168, 258 and 259
were prepared for analysis by removing all visible fat and
connective tissue from the outer surface of the meats. These
samples were analyzed dry and the millimicrograms of biotin
per gram of fresh meat were calculated from the biotin content
per gram of dry meat. Samples 170-257 were prepared for
analysis by removing the rind and bones from the pork hams
and loins. About i inch of fat was left on the outer surface.
The samples were then passed three times through an electric
meat grinder and thoroughly mixed. These samples were
analyzed as prepared and the biotin content per gram of dry
meat was calculated from the biotin content of the moist
meat. The results of the analysis of the meats are found in
table 1.
The selection and preparation of the meats used in the
cooking experiment have been recently reported (Mclntire
et al., '43). The loin and hams were cooked without season
ing by standard cooking procedures (Methods of Cooking and
Testing Meat for Palatability, '33) ; the braising procedure
has been described by Mclntire et al. ('43). In all cases the
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