FOOD. Science. Technology. Quality

Food. SCIENCE. Technology. Quality

Food. Science. TECHNOLOGY. Quality

Food. Science. Technology. QUALITY




Macro- and microelements in determination of different forms of ellagic acid in by-products from strawberry processing


The objective of the research was to select a solvent and the conditions for extracting ellagitanins (ET) from dried by-products from strawberry processing, as well as to develop a method for hydrolyzing ellagic acid (EA) esters in glycerol solutions of trifluoroacetic acid (TFA). Another equal objective was to determine the free and bond EA in some selected by-products from strawberry processing. The results obtained constituted a basis for the calculation of the ET content in the analyzed plant materials. It was evidenced that a 70 % aqueous acetone solution, applied at a room temperature (22 ± 2 ºC) to at least three-step extraction, made it possible to satisfactorily isolate EA and ET from dried strawberry pomace and from post-extraction strawberry achenes defatted under a supercritical CO2 extraction process. It was proved that ET, if maintained at a temperature of 95 ± 1 ºC in a 70 % aqueous glycerol containing 2 M TFA for at least 6 hours, were completely hydrolyzed and the release of free EA occurred. The chromatograms were recorded of extract components before and after the hydrolysis using a HPLC method; this made it possible to determine the content of free and released EA in the selected strawberry by-products and to calculate a percent content of ET therein. It was found that, in the dried industrial seedless strawberry pomace, the content of free EA was below 100 mg/100 g and the content of released EA was about 900 mg/100 g, whereas the percent content of ET was 1.4 % m/m. In the dried industrial residues obtained from a rubbing machine, the content of free EA, released EA, and ET ranged from 30 to 150 mg/100 g, 300 to 600 mg/100 g, and 0.5 to 1.1 %, respectively.


strawberries, strawberry pomace, ellagic acid, ellagitannins, extraction, hydrolysis