Property changes and cholesterol-lowering effects in evening primrose oil-enriched and cholesterol-reduced yogurt

The present study was carried out to investigate the changes in chemical and sensory properties and the cholesterol-lowering effect of evening primrose oil (EPO) addition to cholesterol-reduced yogurt. The rate of cholesterol removal reached 93.5% by beta-cyclodextrin in yogurt before EPO addition. pH, viscosity and microbial counts decreased with amounts of EPO added. The thiobarbituric acid value of cholesterol-reduced and EPO-enriched yogurt increased proportionally to length of storage period and amount of EPO addition, and it was significantly different between the EPO-enriched groups than in unenriched groups in all storage periods. The production of short-chain free fatty acids (FFA) increased with longer periods of storage. From 6 days' storage, the amounts of short-chain FFA in 6 and 10% EPO-enriched groups were significantly different from other groups. Most sensory scores of 2% EPO-enriched group were not significantly different from those of the control, whereas 6 and 10% EPO addition showed an adverse effect on sensory analysis. In blood analysis, the total cholesterol increase after 8 weeks' feeding was dramatically lowered to 39.2% in the 10% EPO-enriched group from 57.7% in the control. In addition, the concentration of blood triglyceride increased in the control, whereas it decreased in the 10% EPO-enriched group. The above results indicated that EPO addition resulted in a profound lowering effect in blood lipids, although it adversely affected some sensory properties.