Factors Affecting the Determination of Available Lysine in Whey with 2,4,6-Trinitrobenzene Sulfonic Acid

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Abstract
Lactose in cheese whey interferes with the determination of biologically avail- able lysine in whey proteins when the reagent 2,4,6-trinitrobenzene sulfonic acid is employed. Loss of the epsilon- TNP-derivative of lysine is dependent up- on the amount of lactose ifi the test ma- terial. The sample weight chosen for analysis also influences results with this reagent. The larger the sample of either pure protein or carbohydrate containing material , the smaller the amount of available lysine found. By careful selec- tion of experimental conditions and by application of a correction formula for lactose interference, the available lysine in whey protein can be rapidly approxi- mated with the 2,4,6-trinitrobenzene sul- fonic acid method. Results compare fa- vorably with those obtained by art estab- lished method.