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Scientists from the US Department of Agriculture (USDA) and the University of Arkansas report that the flavonol content increased as a result of extrusion by between 30 and 34 per cent, but the anthocyanin content was detrimentally affected by the temperature.
"Applications of this research could provide a use for the waste product of cranberry juicing, which currently has little functionality due to its low protein content and low pH," wrote the researchers, led by Luke Howard.
"Furthermore, it could lead to the improved functionality of polyphenolic compounds, particularly procyanidins and flavonols, of cranberry pomace.
"The resulting product could be incorporated into a dietary supplement or explored as a functional snack food," they added.
Cranberry has long been considered an effective method of fighting urinary tract infections, something that has led to almost one third of parents in the US giving it to their children, according to a recent study.
In 2004 France became the first country to approve a health claim for the North American cranberry species Vaccinium macrocarpon, which states that it can 'help reduce the adhesion of certain E.coli bacteria to the urinary tract walls'.
Using pomace provided by Decas Botanicals and corn starch provided by National Starch, Howard and his co-workers prepared a series of extrudates with ratios of 30:70, 40:60, and 50:50 pomace to corn starch at 150, 170, 190 °C.
Results showed that the highest retention of anthocyanins (50 per cent) was achieved at the lowest temperature and 30 per cent pomace.
On the other hand, the flavonol content increased up to 34 per cent at 190 °C, and this was accompanied by an increase in the antioxidant activity, as measured by the ORAC assay.
Interestingly, the procyanidin content of the extrudates increased, particularly for the monomer and dimer where increases of between 61 and 157, and 49 and 164 per cent, respectively, were recorded.
According to the Cranberry Marketing Committee there are 33 suppliers of cranberries, all based in the United States.Growing awareness of the berries has led to increased demand from food and beverage manufacturers and supplement companies for the berry, its juice, and its extracts.
The supply is dominated by Ocean Spray, which produces over half of the nine million barrels of cranberries harvested annually in North America. Second place in the market goes to Decas. The two firms, both based in Massachusetts, together account for around 70 per cent of the North American cranberry market. Decas estimates that it holds about 10 per cent of the market, while Ocean Spray has over 60 per cent.
Source: Journal of Agricultural and Food Chemistry
Published online ahead of print, ASAP Article, doi: 10.1021/jf902838b
"Polyphenolic Composition and Antioxidant Capacity of Extruded Cranberry Pomace"
Authors: B.L. White, L.R. Howard, R.L. Prior