SUMMARY Pectinesterase activity, 3 pectic fractions, and other characteristics were determined periodically on 5 component parts of Valencia oranges during a 7‐month maturation cycle for 2 seasons. Usually, PE activity for peel, membrane, and juice sacs was least in December, when the Brix/acid ratio was low, and highest in June, when this ratio was greatest. The order of component parts for PE in most cases, from highest to lowest activity, was juice sacs, membrane, peel, seeds, and juice. Water‐soluble pectin generally remained constant in peel and juice sacs, increased slightly and then remained constant in the membrane, and was irregular throughout the cycle in the seeds. The trend of ammonium‐oxalate‐soluble pectin in the components was to increase during maturation. Protopectin in the component parts usually increased to a peak and then gradually decreased for the remainder of the season, except that protopectin in the juice sacs decreased throughout the sampling period. In this component, protopectin evidently was at its maximum by the first picking in December. Total pectin remained constant in the juice and seeds, and slowly declined in the other 3 components with maturation. Membrane contained the highest source of protopectin and total pectin throughout the season.
SUMMARY The flavor of orange juices was studied objectively through analyses of recovered volatile materials. Organic extracts of freshly recovered volatiles from juices of established varieties were shown with programmed‐temperature gas chromatography (PTGC) and thermal conductivity detection to contain 40–50 components. Aroma profiles of the different juices were obtained with a programmed‐temperature flame ionization gas chromatograph. Comparative evaluations were conducted of the flavor and aroma patterns of three varieties of Florida oranges: Hamlin, Pineapple, and Valencia. Preliminary investigation revealed no significant qualitative differences among varieties in gross analyses obtained with thermal conductivity an the ionization detection system using PTGC. Quantitative differences appeared responsible for the flavor differences noted among varieties. Analyses showed some compositional differences among varieties in control juices, peel‐oil‐free juices, their respective juice essences, and peel oils. The presence of certain chemical constituents in the juice was directly related to the peel oil. No significant qualitative differences existed in similarly prepared samples from different varieties. Some specific chemical identification and the methods used are outlined.
SUMMARY Pectinesterase activity, 3 pectic fractions, and other characteristics were determined periodically on 5 component parts of Pineapple oranges during a 9.month maturation cycle for 2 seasons. Generally, PE activity was greatest in the peel, membrane, and juice sacs in March, April, and May, when the Brix/acid ratio was highest. However, the activity varied in similar components for like months during the 2 seasons. The order of component parts for PE in most cases, from highest to lowest activity, was juice sacs, membrane, peel, seeds, and juice. Total PE in the average whole orange attained maximum activity in March and April. Over 52% of the activity present was found in the juice sacs, which represented about 22.5% of the whole fruit. Water‐soluble pectin increased slightly in the peel and membrane, remained somewhat irregular in the juice sacs, and decreased to a constant level in the seeds throughout the growing season. Ammonium‐oxalate‐soluble pectin in the peel decreased slightly, and in the other components was either irregular or increased slightly, during maturation. Quantity of protopectin was greatest in the membrane and generally decreased toward the end of the sampling period in the various components. Total pectin and weight of the average whole orange was greater in the 1961–62 season than in the preceding season.
In the early production of frozen concentrated orange juice (FCOJ) several factors contributed to a product quality that closely resembled the fresh juice fed to the evaporator. Among these were: fruit selection, a moderate juice yield, no heat treatment, low evaporator temperatures, cutback juice (8)2, and selected coldpressed orange oil (7). Paper published with permission.
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