BACKGROUND: The presence of lipid oxidation products in the Maillard reaction pathway is of particular interest today. The objective of this study was to investigate the effect of lard and its oxidation products on the formation of volatiles from cysteine and xylose model systems. RESULTS: Headspace volatiles generated in reaction mixtures were examined by solid-phase microextraction in combination with gas chromatography-mass spectrometry. The addition of lipid had a suppressing effect on most of the sulfur-containing compounds derived from the reaction between cysteine and xylose, especially for 2-methyl-3-furanthiol, 2-furanmethanethiol, 2-methylthiophene, and 3-methylthiophene. One of the intermediates-furfural-was also formed in much lower concentration when lard was present. In addition, cysteine and xylose modified lipid oxidation pathways, so that lipid-derived alcohols, alkylfurans and aliphatic acids were formed rather than aldehydes. Compared with the lard heated alone, most aldehydes were formed at lower levels in the lard-containing reaction mixtures, and several aldehydes including hexanal, heptanal, (2E)-heptenal and (2E,4E)-heptadienal were absent. CONCLUSION: The addition of lipid was inhibitory to the formation of most sulfur-containing compounds in the Maillard reaction. Furthermore, Maillard reaction products influenced the formation of products from lipid oxidation.
BACKGROUND: The presence of lipid oxidation products in the Maillard reaction pathway is of particular interest today. The objective of this study was to investigate the effect of lard and its oxidation products on the formation of volatiles from cysteine and xylose model systems. RESULTS: Headspace volatiles generated in reaction mixtures were examined by solid-phase microextraction in combination with gas chromatography-mass spectrometry. The addition of lipid had a suppressing effect on most of the sulfur-containing compounds derived from the reaction between cysteine and xylose, especially for 2-methyl-3-furanthiol, 2-furanmethanethiol, 2-methylthiophene, and 3-methylthiophene. One of the intermediates-furfural-was also formed in much lower concentration when lard was present. In addition, cysteine and xylose modified lipid oxidation pathways, so that lipid-derived alcohols, alkylfurans and aliphatic acids were formed rather than aldehydes. Compared with the lard heated alone, most aldehydes were formed at lower levels in the lard-containing reaction mixtures, and several aldehydes including hexanal, heptanal, (2E)-heptenal and (2E,4E)-heptadienal were absent. CONCLUSION: The addition of lipid was inhibitory to the formation of most sulfur-containing compounds in the Maillard reaction. Furthermore, Maillard reaction products influenced the formation of products from lipid oxidation.