These antioxidants have numerous health benefits.
The study by researchers The Hershey Company and Brunswick Laboratories of Norton, MA aimed at finding the levels of antioxidants in selected cocoa powders and the effect of processing on the antioxidant levels.
The researchers went on to analyse Hershey's Natural Cocoa Powder and nineteen other cocoa powders, and found that natural cocoa powders contained an average of 34.6 mg of flavanols per gram of cocoa powder, or about 3.5pct of total flavanols by weight.
Thus, the study ranked cocoa powder among the foods highest in these types of antioxidants.
The researchers looked at a variety of Dutched (alkaline processed) cocoa powders, which are commonly used by the food industry.
Dutching, or alkali treatment, of cocoa is a 180-year-old process used to lower the bitterness and darken the color of cocoa powder. Dutched cocoas are commonly used in beverages such as chocolate milk and hot cocoa mixes, in cakes and cookies, and in a limited number of confections.
The results indicated that the Dutched cocoa powders, particularly the light- and medium-Dutched cocoa powders, had a tendency to retain significant amounts of cocoa flavanol antioxidants.
In fact, no matter what were the losses created by light to medium Dutch processing, these cocoa powders still made a place in the top 10pct of flavanol-containing foods when results were compared to foods listed in the USDA Procyanidin Database.
"This is an important finding for people who like all things chocolate. Because cocoa powder is one of the richest sources of flavanol antioxidants to start with, even lightly- or medium-Dutched processed cocoa powders still retain significant levels of the beneficial antioxidants." said Ken Miller, the lead author of the paper.
The researchers found that the degree of cocoa alkalization led to a progressive, but not complete loss, of flavanol antioxidants, with about 40pct retained in lightly dutched cocoas, 25pct retained in medium dutched cocoas, and 10pct retained in heavily dutched cocoas.
The study is published this month in the Journal of Agricultural and Food Chemistry.