REVERSE-OSMOSIS CONCENTRATION OF AQUEOUS-PHASE CITRUS JUICE ESSENCE

Dilute aqueous essences of 2 to 20% ethanol obtained from commercial orange juice evaporators when concentrated to 31% ethanol by reverse osmosis resulted in increased concentration of the small aroma molecules and acetaldehyde. Rejection of ethanol varied from 90% at 2% ethanol to 40% at the highest concentration achieved (31%). Acetaldehyde rejection varied from about 65% at 2% ethanol, to an extrapolated low value of 25% at 31% ethanol. Rejection was generally greater than 85% for larger aroma molecules, e.g., ethyl butyrate, hexanal and terpenes. Permeate flux rates followed a first order decay with increasing ethanol concentration, from greater than 300 at 0.01% ethanol to 26 L/H/module at 31% ethanol, 8.3 MPa, 30-degrees-C.