Vakaleris-Price and Hull Methods for Determining Soluble Tyrosine and Tryptophan in Blue Cheese

To establish a suitable method for measuring the degree of proteolysis in blue cheese (as a measure of ripening), the Hull procedure and the Vakalaris-Price method were compared. In recovery experiments using three different spectrophotometers and known amounts of tyrosine and tryptophan, discrepancies between the three spectrophotometers in their absorbance readings at 290 nm were wide. To eliminate discrepancies that could have been caused by differing sensitivities of instruments, we used a wavelength of 285 nm instead of 290 nm.