It is well-known that many processing techniques may affect the concentrations and bioavailability of a range of fruit and vegetable extracts. For example, processing tomatoes is known to boost the availability of lycopene, while processing of broccoli is said to reduce activity of an enzyme responsible for producing the potential anti-cancer benefits of the vegetable.
Results of a human study just published in the Journal of Agricultural & Food Chemistry now indicate that consuming fresh or thermally processed strawberry puree produces similar production of compounds called urolithins.
“Strawberry polyphenols, and particularly ellagitannins and ellagic acid, have been associated with the health benefits of this berry for humans,” explained researchers led by Mar Larrosa from the Research Group on Quality, Safety and Bioactivity of Plant Foods at the Department of Food Science and Technology, CEBAS-CSI in Murcia.
“These compounds are transformed into urolithins by the gut microbiota, and these metabolites exert several biological activities that could be responsible for the health effects of strawberries.”
The researchers produced a thermally processed strawberry puree and compared this to the same amount of fresh strawberries in 20 human volunteers.
Results showed processing increased the amount of free ellagic acid 2.5-fold. However, this had no effect on the production of urolithins by the gut microbiota between the fresh and processed strawberry groups.
This result showed “that the release of ellagic acid from ellagitannins is not a relevant factor affecting the microbial metabolism”, said the Murcia-based scientists.
The results also showed the effects of inter-personal differences between the subjects with all of the volunteers producing urolithin A, while only 3 produced and excreted urolithin B.
“It is confirmed that some volunteers were efficient producers of urolithins, whereas other produced much lower amounts,” they said.
“These results show that processing does not modify the potential health effects of strawberry polyphenols.”
Source: Journal of Agricultural & Food Chemistry
Published online ahead of print, doi: 10.1021/jf203641r
“Strawberry Processing Does Not Affect the Production and Urinary Excretion of Urolithins, Ellagic Acid Metabolites, in Humans”
Authors: P. Truchado, M. Larrosa, M.T. Garcia-Conesa, B. Cerda, M.L. Vidal-Guevara, F.A. Tomas-Barberan, J.C. Espin