Summary - B6 by microbiological assay
EN 14166:2009 Foodstuffs - Determination of vitamin B6 by microbiological assay:
This European Standard specifies a method for the determination of total vitamin B6 in foodstuffs by microbiological assay (MBA). Vitamin B6 is determined as the mass fraction of pyridoxine, pyridoxal and pyridoxamine, including their phosphorylated or glycosylated derivatives. It is usually expressed as milligram vitamin B6 per 100 g of foodstuff. The method is applicable to samples that can be rendered homogeneous and do not contain high concentrations of antibiotics or other interfering substances.
This method has been validated in an inter-laboratory test on fortified and non-fortified samples such as wholemeal flour, milk powder, mixed vegetables and pigs liver at levels from 0,5 mg/100 g to 1,9 mg/100 g.
Pyridoxine, pyridoxal and/or pyridoxamine are extracted from foodstuffs by acid hydrolysis. The hydrolysis step liberates the vitamin B6 vitamers from proteins and carbohydrates in the sample and hydrolyses the phosphates to the free vitamers. The total vitamin B6 content in the sample extract is then determined by comparing the growth response of the assay test organism against growth obtained from a pyridoxine hydrochloride standard.