Oxidation mechanisms in real food emulsions: oil-water partition coefficients of selected volatile off-flavor compounds in mayonnaise

A method for the determination of oil/water partition coefficients, P(o/w), for volatile lipid oxidation products in mayonnaise enriched with fish oil has been developed. Selected volatile off-flavor compounds (2-pentenal, 3-heptanone, octanal, 1-octen-3-ol, 2,4-heptadienal, and 2-nonanone) were added in levels ranging from 80 to 480 ng/g mayonnaise. The mayonnaises were separated by a procedure involving freezing, centrifugation, and ultracentrifugation. The P(o/w) values were then determined from the concentrations of volatiles quantified by dynamic headspace gas chromatography on the separated lipid and aqueous phases. The P(o/w) values for the selected volatiles ranged from 4.9 to infinity. Increased addition levels of the six volatile compounds resulted in an increase of the apparent P(o/w) values and higher recoveries of the volatiles. Also, the effect on P(o/w) values of an additional emulsifier (Panodan TR) and three different antioxidant systems (Grindox 1032, Toco 70, and ascorbic acid) added to mayonnaise was studied. Addition of ascorbic acid seemed to increase recoveries, which resulted in higher P(o/w) values. In contrast, addition of extra emulsifier and a water dispersible tocopherol preparation (Grindox 1032) resulted in lower P(o/w) values and lower recoveries for analysis. We propose that the effect of Grinder 1032 addition may be due to the ability of this antioxidant preparation, via its emulsifier content, to promote increased binding or entrapment of volatile compounds at the oil/water interface of mayonnaise. The data may be useful for selecting antioxidant and emulsifier systems to mask off-flavor development in food emulsion systems.