Composition and Sensory Characterization of Red Raspberry Juice Concentrated by Direct‐Osmosis or Evaporation

Abstract

Raspberries were processed into juice and concentrated to 45 "Brix by two processes: Osmotek's cold, direct-osmotic concentration process and conventional evaporative technology. Compositional analyses included pH, titratable acidity, form01 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.

On the direct osmotic concentration of liquid foods: Part II. Development of a generalized model

“…Non-fouling tests showed that fouling layer resistance is negligible. A similar finding was published by other workers (Wrolstad et al, 1993).…”

Recent advances on membrane processes for the concentration of fruit juices: a review

“…The flux to make 42°Brix pulpy orange juice was similar. The time required to concentrate raspberry juice to 45°Brix approximately doubled (5 h vs. 10 h) when the processing temperature decreased from 26 to 8°C (Wrolstad et al, 1993).…”

“…Raspberry concentrates (45°Brix) prepared by Osmotek's DOC system were compared with conventional evaporative technology (i.e., centrifugal film evaporator) (Wrolstad et al, 1993). Concentration by either processes resulted in small anthocyanin pigment losses, small increases of polymerized pigment and no significant flavor differences as compared to the single-strength juice.…”

Membrane Technologies for Point-of-Use and Point-of-Entry Applications

“…Forward osmosis has been used to treat industrial wastewaters (at bench scale) (32)(33)(34), to concentrate landfill leachate (at pilot and full scale) (35)(36)(37), and to treat liquid foods in the food industry (at bench scale) (38)(39)(40)(41)(42)(43)(44)(45)(46). FO is also being evaluated for reclaiming wastewater for potable reuse in life support systems (at demonstration scale) (47)(48)(49)(50), for desalinating seawater (51,52), and for purifying water in emergency relief situations (53).…”