PHOSPHOLIPID DEGRADATION IS INDUCED BY HEAT IN ALPHA-TOCOPHEROL-ENRICHED EGGS

A comparative study was undertaken to determine the effect of an alpha -tocopherol- and iodine-enriched laying diet on the phospholipid profi le of egg yolk. In addition to the comparative study between the exper imental and control eggs, experiments were conducted to determine the effects of heating on the phospholipid profile and the comparative mol ar ratios of cholesterol and total phospholipid. The phospholipid comp osition determined for frozen egg yolk samples showed no differences f or the major components of phosphatidylcholine and phosphatidylethanol amine between the control and experimental diet group. In control eggs , exposure to boiling water produced time-related elevations in the co ncentration of lyso-phosphatidylcholine. A similar heat-related elevat ion in lyso-phosphatidylethanolamine was observed in both groups after 10 min. A time shift was observed in the heat susceptibilities of the experimental diet group. The control egg yolks hardened more quickly when exposed to heat. The results suggest protection against oxidative degradation of phospholipids and possible inhibition of phospholipase s A(2) and C, which may result from the elevated level of alpha-tocoph erol in the experimental egg yolks.