Application of microencapsulation technology to improve the stability of citral in rodent diets

Citral is a widely used flavoring and scenting agent which is employed in numerous food, industrial, and household products. Although the current regulatory status of citral lists it as a GRAS chemical on the FDA list, the chemical is a reactive beta-substituted vinyl aldehyde that has been shown to induce irritations of skin and mucous membranes, and to exhibit a dose-dependent teratogenic effect on embryos of white leghorn chickens. Because of these factors, citral was nominated by the National Toxicology Program for carcinogenesis study. Stability studies of dose formulations of citral (0.02%) in NIH-07 rodent diet indicated a loss of 41% of the citral after 1 day in a rat cage, due mainly to volatility and reactivity with diet components. The chemical was subsequently microencapsulated using a shell medium of food-grade modified cornstarch and sucrose, and then formulated into NIH-07 diet (0.02%) for various stability studies. Results after 7 days in a rat cage showed 95% retention of chemical; diet that had been stored 21 days retained 95% at 5 degrees C storage and 89% at room temperature. An assessment of the purity of the citral in the microcapsules indicated that total impurities increased from 0.7% in the neat chemical to 1.1% in the encapsulated chemical.