Original article

A new liquid chromatography method for the simultaneous and sensitive quantification of lactose and lactulose in milk

种新的液相色谱法同时检测乳中乳糖和乳酮糖

Regina Schuster-Wolff-Bühring^*, Ronnie Michel and Jörg Hinrichs

Department of Dairy Science and Technology, Institute of Food Science and Biotechnology, University of Hohenheim, Stuttgart, Germany

^* Corresponding author (通讯作者): gini@uni-hohenheim.de

Received: 13 January 2010
Revised: 16 April 2010
Accepted: 30 April 2010

Abstract

The disaccharide lactulose is known to have a large influence on human digestion, the effects of which range from prebiotic to laxative action. Lactulose can be derived from lactose by either alkaline isomerization or enzymatic transgalactosylation of fructose. The aim of this study was to establish a new analytical method for the quantification of both disaccharides lactose and lactulose using high performance liquid chromatography (HPLC) and evaporative light scattering detection (ELSD). The new method needs to provide good chromatographic separation of lactose and lactulose while being fast and reliable. Therefore, four analytical methods using different HPLC columns were developed and compared. A HPLC column with an amino-bonded polymeric matrix yielded better results compared to amino-bonded silica-phase resin or cation-exchange resin. The new method had detection limits for lactose and lactulose of 3.8 and 2.5 mg·L⁻¹ and was successfully applied to the quantification of lactulose and lactose in commercial milk products.

摘要

乳酮糖为二糖，具有益生元的功能。乳酮糖除对人消化能力有较大的影响外，还具有对人体放松的作用。乳酮糖的制备可以采用乳糖在碱性条件下的异构化作用或者在酶催化下发生果糖的转半乳糖苷作用。本文建立了配以蒸发光散射检测器 (ELSD) 的高效液相色谱法 (HPLC) 测定乳糖和乳酮糖的定量检测方法。新的色谱条件必须保证乳糖和乳酮糖有较高的分离度，并且具有快速和准确的特点。因此，选用不同的色谱柱用四种分析方法对测定结果进行了比较和分析。与氨基键合硅胶柱或阳离子交换树脂柱相比，氨基键合柱可以将乳糖和乳酮糖较好地分离。所建立的方法对乳糖和乳酮糖的检测限分别为 3.8 和 2.5 mg·L⁻¹。该方法可以成功地用于乳制品中乳糖和乳酮糖的定量测定。