The American Cranberry: Evolution for Fruit Preservation
Nicholi Vorsa
Department of Plant Pathology and Plant Biology
Cook College, Rutgers University, NJ
The American cranberry, Vaccinium macrocarpon has received much attention for its potential benefits to human health. Most of the attention has focused on the amelioration of urinary tract infection caused by uropathogenic E. coli. Cranberry fruit was found to have A-type proanthocyanidins which inhibit P-fimbriated E. coli from adhering to uroepithelial cells. Proanthocyanidins are well known for their anti-microbial and anti-herbivory activities. Many plant species have utilized fruit as vehicle for seed dispersal with the fruit becoming edible during fruit ripening and maturation, with increases in sugar levels, a reduction in proanthocyanidins and lowering of acids, thus encouraging consumption. Although some animals will consume cranberries, many attributes of the cranberry fruit suggest that cranberry has developed a water dispersal strategy for seed dispersal. The fruit is hollow making it highly buoyant, and proanthocyanidin and acid levels remain relatively high, while sugar levels are lower than in other fruit crop species. Cranberry is one of species which contains relatively high levels of benzoic acid, a known antifungal preservative. In addition, cranberry is among the highest in levels of proanthocyanidins and flavonols relative to other fruit crops. The predominant flavonol aglycone in cranberry is quercetin and is found in at least 22 conjugated forms. Many reports indicate that quercetin and derivatives of quercetin exhibit anti-bacterial and anti-fungal activity. Cranberry also contains high levels of epicatechin and epicatechin oligomers and high molecular weight proanthocyanidins which are used in the tannin industry.