COMPOSITION AND SENSORY CHARACTERIZATION OF RED RASPBERRY JUICE CONCENTRATED BY DIRECT-OSMOSIS OR EVAPORATION

Raspberries were processed into juice and concentrated to 45-degrees-Brix by two processes: Osmotek's cold, direct-osmotic concentration process and conventional evaporative technology. Compositional analyses included pH, titratable acidity, fomol value, total anthocyanin pigment, polymeric color, and nonvolatile acid, sugar and anthocyanin pigment profiles. Concentration by either process resulted in small anthocyanin pigment losses and formation of fumaric acid and small increases of polymerized pigment. The aroma and flavor of the experimental samples and nine commercial concentrates were evaluated in a raspberry drink formulation by a trained descriptive flavor panel. Principal component analysis revealed no significant flavor differences between the single-strength juice, the concentrates and three of the commercial samples.