OXISTEROL DETERMINATION IN SELECTED COFFEES

The main aim of green-coffee processing techniques, such as decaffeination and roasting, is always to maintain a very high level of quality in taste and flavor, the beverage's most important characteristics to consumers. Oxidative alterations of coffee lipids, which can occur in roasting, exert a very marked influence on these quality traits. Determining the extent of oxidation thus can provide an indication of the product's potential shelf-life and reveal traces of any newly-formed oxidative products that might prove nutritionally unsafe. Yet, while much attention has recently been focused on certain by-products induced by cholesterol oxidation and their proven toxicity as risk factors in atherosclerosis and cancer, oxidated phytosterols have largely gone unnoticed, being considered along with beta-sitosterol as not very dangerous in that neither is absorbed by the intestinal tract. The present study investigates the substances derived from phytosterol oxidation (oxisterols) in samples of regular and decaffeinated commercial coffees. The findings show that oxisterols were absent in some samples and that the traces of oxidate phytosterols detected in others were well below the threshold considered as toxicologically active.