Modification of maillard browning in a microwaved glucose/glycine model system by water‐soluble natural antioxidants and foods containing them

Abstract

AbstractInhibition of pyrazine formation by natural antioxidants and the foods containing them was measured in a microwaved glucose/glycine model system. Inhibition of lipid oxidation by the same materials was assayed in both bulk and emulsion systems. Pyrazines were determined by solid‐phase micro extraction followed by GC. Lipid oxidation volatiles were assayed by polyamide fluorescence produced by either a bulk oil display or a hematin‐ or 2,2′‐azobis‐(2‐amidino=propane) dihydrochloride‐accelerated lecithin or fish oil emulsion. It was shown that (i) the inhibition of pyrazine formation depends on high concentrations of water‐soluble antioxidants; (ii) such antioxidants occur naturally in some foods and are usually polyphenols; (iii) during pyrazine inhibition, oxidized polyphenols show enhanced nonfluorescing browning similar to enzymic browning products; (iv) monophenols, which structurally cannot form quinone polymers on oxidation, inhibit pyrazines with less browning; (v) during the final pyrazine‐forming phase of the Maillard reaction, polyphenolics and reducing agents such as glutathione and ascorbic acid are partially consumed with some nutritional loss; (vi) fruit powders of grape seed, grape skin, and red wine are highly pyrazine‐inhibitory, steeped blueberry strongly so, but plum purees are moderately pro‐pyrazine, and freeze‐dried vegetables strongly pro‐pyrazine; and (vii) black and green tea infusions are highly inhibitory, whereas spices have mixed effects.