MACRO- AND MICROELEMENTS IN DETERMINATION OF DIFFERENT FORMS OF ELLAGIC ACID IN BY-PRODUCTS FROM STRAWBERRY PROCESSING

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MACRO- AND MICROELEMENTS IN DETERMINATION OF DIFFERENT FORMS OF ELLAGIC ACID IN BY-PRODUCTS FROM STRAWBERRY PROCESSING

Journal Title: Żywność. Nauka. Technologia. Jakość - Year 2010, Vol 17, Issue 4

Abstract

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.

Authors and Affiliations

Elżbieta Klimczak, Bogusław Król

Keywords

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EP ID EP121789
DOI 10.15193/zntj/2010/71/081-094
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