Influence of oxidized lipids on the non-enzymic browning reaction: interaction between linolenic acid and an Amadori compound

Abstract

The formation of 4-( d- arabino-tetritol-1-yl)-1-butyl-3-pyrrolecarbaldehyde ( 1) and 3-( d- arabino-tetritol-1-yl)-1-butyl-4-pyridone ( 2) in the non-enzymic browning reaction at pH 6 of 1-butylamino-1-deoxy- d-fructose (BAF) in the presence of linolenic acid (LNA) was studied. 1 and 2 are products of the reaction of the amino sugar with the malondialdehyde (MDA) that results from the oxidative degradation of the LNA. Identification and quantification of both heterocycles was carried out using high resolution gas chromatography (HRGC) and GC-MS of their O-trimethylsilyl derivatives. Oxidative conditions were necessary for browning development in the interaction BAF-LNA and the results were different according to oxidative conditions. Thus, using the 13-OOH of LNA (13-LNOOH), the initial level of thiobarbituric acid reactive substances (TBARS) and the browning were lower than when chemically oxidized LNA was used. In addition, the quantification of the heterocycle 2 (>99% extractable with ethyl acetate from aqueous reaction solutions) was used to determine the amount of MDA produced and reacted with BAF. 13-LNOOH was found to produce a lower amount of MDA (0.06%) than chemically oxidized LNA (0.54%). In the latter case, the amount of MDA had a threefold increase (1.48%) when the reaction mixture was preincubated for 24 h at room temperature.