STRAWBERRY ANTHOCYANIN DETERMINATION BY pH DIFFERENTIAL SPECTROSCOPIC METHOD - HOW TO GET TRUE RESULTS?

The aim of the research was to analyse the weaknesses of the pH differential method for strawberry anthocyanin determination. The work is based on practical experi- ments with 12 strawberry cultivars and on analysis of published papers. We used follow- ing molar absorption coefficients (�0 values): 26900 and 29600 M -1 cm -1 for cyanidin 3 glycoside (C3g) and 15600, 22400, 27300 and 36000 M -1 cm -1 for pelargonidin 3 glyco- side (P3g). In order to show how the calculated value of total anthocyanins depends on the predominant anthocyanin used for the calculations, we compared the results of spectro- scopic and chromatographic analysis. Present research demonstrated that different �0 val- ues may influence the results of total anthocyanins even more than cultivar properties. The most frequently used �0 values 26900 M -1 cm -1 and 29600 M -1 cm -1 gave underesti- mated values. C3g was present in minor amounts in all cultivars. Conclusively, P3g with the �0 = 15600 M -1 cm -1 should be used for ensuring most precise estimation of total antho- cyanin content in strawberries.