A Fast and Selective HPLC Determination of Ulose Formation during Enzymatic Isomerisation of Pentose Rich Syrups
2010
Givry, S | Duchiron, F | Bliard, C.
Xylose, and arabinose rich syrups obtained by hydrolysis of wheat bran represent a large potential as fermentation substrates in the production of second generation biofuels (1), providing that pentoses are isomerised into the 2-ulose form previously, or during in the fermentation process. The transformation of arabinose and xylose present in pentose rich syrups into the corresponding ketoses using immobilised isomerases produces a very effective fermentation medium. (2). Existing analytical protocols to monitor the isomerisation rate, such as the carbazol test (3) or the resorcinol method (4) do poorly on concentrated syrups containing a mixture of various types of aldoses, especially at low and medium ulose concentrations. In order to closely monitor the action of the isomerase on the sugar mixture we developed a new fast and selective high performance liquid chromatographic (HPLC) analysis of the produced uloses, directly in the concentrated complex carbohydrate mixtures (5). This method uses the UV absorption specificity of the open-chain ketose form at 210 nm. The test is linear up to a concentration of 20 g/L ketose even in the presence of 50 g/L D-xylose or L-arabinose. The sensitivity of th method is 0.5 g/L for D-xylulose and L-ribulose.
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