Peanut skins were the source of oligomeric proanythocyanidins (OPCs), dimers, trimers and tetramers of the procyanidin monomers, identified by French scientist Masquelier about half a century ago. Now, in a new study published in the Journal of Food Composition and Analysis (Vol. 19, pp. 364-371), lead author Jianmei Yu from North Carolina A&T State University, says they could provide an inexpensive source of natural antioxidants, such as catechins and procyanidin, for use in food and dietary supplements.

Procyanidins, polyphenolic compounds found naturally in and more commonly associated with green tea, fruit, vegetables and red wine, have been linked to a wide range of health benefits, including reduced risks of cardiovascular disease and some cancers. In fact marketing of antioxidants means that many people are familiar with sources of polyphenols such as green tea extracts, like Teavigo and Sunphenon, grape seed extracts, like Anthogenol, and pine bark extracts like Pycnogenol.

Yu's study investigated three different peanut skin removal techniques (direct peeling, blanching or roasting). The total polyphenol yield for the three removal techniques were 130.8, 15.1, and 124.3 milligrams gallic acid equivalents (GAE) per gram of dry skin for the direct peeling, blanching or roasting techniques respectively. Boiling in water and then peeling (blanching) and roasting at 175 degrees Celsius followed by the standard ethanol extraction, significantly altered the procyanidin profiles compared to direct (untreated) skin removal. The heat based approaches destroyed the polyphenolics such as caffeic acid, chlorogenic acid, ellagic acid and resveratrol.

The procyanidin compositions of the extracts were compared to those of grape seed varieties. The yield of catechins was significantly less for the peanut skin extract. However, the concentration of OPCs was found in comparable quantities to those found in grape seed extracts.

The total antioxidant activity (TAA) of the peanut skin extracts increased almost linearly with increasing concentration of total phenolics, and they were higher than those of Trolox and vitamin C with exception of TAA of crude extract from the blanched peanut skin. The free radical scavenging capacity (FRSC) of the extracts was also greater than Trolox and vitamin C, with the extract of the direct peeled peanut skin having the highest FRSC of all the extracts.

The US Department of Agriculture claims a healthy diet should provide an adequate intake of OPCs, with studies showing a benefit of OPCs with doses in the range of 100 to 300 milligrams a day. Some studies have suggested that intake of an average diet is only around 25 mg per day. So it seems quite possible that a new wave of antioxidants may soon be marketed, based on the "miracle power of peanuts," or something like that. After, of course, the usual astonishingly convincing scientific studies can be produced to "independently" underwrite the marketing campaigns.