INFLUENCE OF ACID AND BASE HYDROLYSIS ON THE PHENOLIC COMPOSITION OF RED RASPBERRY JUICE

Acid and base hydrolysis simplified the complex HPLC chromatographic profile of red raspberry juice phenolics dramatically. In three acid-hydrolyzed juices, ellagic acid, two unidentified ellagic acid compounds, and gallic, p-hydroxybenzoic, protocatechuic, caffeic, p-coumaric, and ferulic acids, as well as (+)-catechin, (-)-epicatechin, quercetin, and kaempferol were separated and identified using HPLC diode array spectral techniques. The percentages of HPLC peak area for these phenolics were similar in the acid-hydrolyzed juices. In base-hydrolyzed samples the same phenolics, except the second ellagic acid compound, were present, and the first ellagic acid compound was present in smaller quantity. Sep-Pak C18 cartridges were used for sample preparation. Hydrolysis could become a very useful tool for rapidly screening raspberry juices for qualitative deviations from authentic HPLC profiles to determine adulteration by other fruit juices or phenolic mixes.