Enzymatic determination of free glutamic acid in dried soups and in minced sausages: NMKL collaborative study.
An enzymatic method for the determination of free glutamic acid in meat products and dried soups was collaboratively studied in 11 laboratories. In the presence of the enzyme glutamate dehydrogenase, L-glutamic acid is oxidatively deaminated by nicotinamide adenine dinucleotide (NAD) to 2-oxoglutarate. In a reaction catalyzed by diaphorase, the NADH thus formed converts 2-(p-iodophenyl)-3-(p-nitrophenyl)-5-phenyltetrazolium chloride to a formazan, which is measured in the visible range at 492 nm. Fourteen samples (7 samples of minced sausage and 7 samples of dried cauliflower soup) with glutamate contents varying between 0.4 and 16 g/kg were included in the study. Materials were distributed to participants as blind duplicates and as split level pairs. The mean relative standard deviation (RSDR) for reproducibility for the dried soup material containing glutamate between 7 and 16 g/kg was 4.6%. RSDR values for samples of minced sausage containing glutamate at lower levels (0.4-1.3 g/kg) were between 12 and 16%.
Hattula
M T
MT
Technical Research Centre of Finland, Food Research Laboratory, Espoo.
Wallin
H C
HC
D005503:Food Additives / Q000032:analysis*; D005504:Food Analysis / Q000379:methods*; D005969:Glutamate Dehydrogenase / Q000378:metabolism; D005971:Glutamates / Q000032:analysis* / Q000378:metabolism; D018698:Glutamic Acid; D007656:Ketoglutaric Acids / Q000378:metabolism; D008461:Meat Products / Q000032:analysis*; D009243:NAD / Q000378:metabolism; D013053:Spectrophotometry
D005503:Food Additives; D005971:Glutamates; D007656:Ketoglutaric Acids; D009243:NAD; D018698:Glutamic Acid; D005969:Glutamate Dehydrogenase