Lutein enhances functional properties of yogurt.

Research indicates that lutein may help protect the eyes and skin from oxidative stress and harmful blue light. While dark green leafy vegetables, egg yolk and corn are naturally rich in the carotenoid, dairy products are not good sources of lutein.

Scientists at Louisiana State University and elsewhere wanted to determine the impact of various levels of lutein on the physico-chemical, microbiological and sensory characteristics of yogurt over its shelf life. The idea is to nutritionally enhance the product. Their results suggest that lutein is suitable for inclusion in functional yogurts. The skin and eye health benefits of lutein can easily be incorporated into yogurt to complement its inherent nutritional properties.

In experiments, nonfat strawberry yogurts were prepared with 0 mg, 0.5 mg, 1.5 mg and 3.0 mg of lutein per 6-oz serving. The researchers included 20% overages to account for processing losses. The lutein was incorporated prior to homogenization of the yogurt mix. The investigators studied the stability of lutein, its viscosity, pH, syneresis, standard plate counts, coliform counts, instrumental color (L*,a*,b*), sensory flavor, body texture, appearance and color at certain intervals up to five weeks after product manufacture. Three readings were recorded per replication, and two replications were conducted.

The researchers analyzed data and determined significant differences. Lutein did not impact viscosity, pH, syneresis, standard plate counts, coliform counts, sensory body texture, appearance and color of the yogurts. Significantly higher flavor scores were obtained for yogurts fortified with 1.5 mg lutein per serving.

Yogurts with lutein levels of 1.5 mg and 3.0 mg per serving had significantly lower L* (lightness) values compared to the yogurts with 0 mg and 0.5 mg lutein per serving. The interaction effect between levels of lutein and storage time was significant for a* (redness) values. Lutein levels remained above target levels throughout the five-week storage study.

Further information. Kayanush Aryana, Department of Dairy Science, Louisiana State University Agricultural Center, 115 Dairy Science Building, Baton Rouge, LA 70803; phone: [phone]; fax: [phone]; email: [e-mail].