Glutamate determination in foodstuffs with a very simple HPLC-UV method

Abstract

To date, monosodium glutamate is the most used flavour enhancing food additive. Because high levels of glutamate are toxic to brain concerns appeared regarding the safe use of glutamate and there is a 10 g kg −1 concentration limit in foodstuff. A simple HPLC-UV method, based on a derivatization procedure with o -phthaldialdehyde, was developed for determination of glutamate in meat products, soup bases and vegetable concentrates. Even if our method is less sensitive than the HPLC-fluorescence ones widely available, it is able to measure amounts at least 200 times smaller than the maximum allowed one, has good reproducibility (CV under 2% for intraday and under 3% for interday determinations), linearity and accuracy. Less expensive HPLC systems are required and the formed derivative is very stable (at least 1 week), good separation is obtained with the less expensive 5 μm particle C 18 columns and methanol as organic phase. Concentration of free glutamate ranged between 0.14 g kg −1 in sausage without added glutamate to as high as 2.16 g kg −1 in a pork sausage. Concentration in vegetable mixes and soup bases were between 80–120 g kg −1 .