Biotin assessment in foods and body fluids by a protein binding assay (PBA).

The biotin content of plant and animal food samples as well as of human plasma and urine specimens was assessed by a modified protein binding assay (PBA). Protein bound biotin in samples was released by digestion with papain, food samples were in addition treated previously with liquid nitrogen. Comparing analyses by use of the conventional microbiological test with L. plantarum resulted in slightly enhanced biotin values, in case of plasma by 9.2% and in case of urine by 10.3%, but the results obtained by both methods correlated well (r = 0.926 for plasma and 0.934 for urine). Regarding food analysis the additional comparison of different disintegration procedures led to best reproducible results by using the PBA with preceding papain digestion.