Anthocyanin pigment, nonvolatile acid and sugar composition of red raspberry juice

Graduation date: 1986Seven red raspberry (Rubus Ideaus L.) samples from Oregon, Washington, British Columbia and New Zealand were processed into juice. These, along with three juice samples supplied from West Germany were analyzed by high performance liquid chromatography, (HPLC), for nonvolatile acid, sugar, anthocyanin and anthocyanidin composition. In\ud order to quantitate the compounds of interest, particular attention was given to selection and improvement of HPLC analytical procedures. Adequate resolution of malic acid\ud from isocitric by reverse phase C-18 chromatographic media was achieved using a two column system. The more uniform response of analytes to refractive index detection allowed for quantitation of isocitric acid. Sugar analysis based on a crosslinked cation exchange resin required removal of the acids from the juice via anion exchange. Resolution of anthocyanin pigments was achieved using as organic modifier 15% acetic acid. Acetic acid (15%) demonstrated high selectivity in resolving pigments with similar polarity. Ultraviolet-visible spectral techniques were employed to determine anthocyanin concentration, color density, polymeric color and browning index. Other data presented include °Brix, pH, titratable acidity, Stable Isotopic Carbon Ratios and Hunter color parameters. Data compiled are intended to create a reference data base for authentic red raspberry juice