Orange juice, fresh-squeezed

Fruit juices and nectars are highly susceptible to fermentation and other forms of microbial spoilage and with few exceptions it is essential that some form of pasteurisation is employed when these products are packaged. The exceptions that are seen usually relate to freshly squeezed orange (or other) juices that are processed directly from fresh fruit and packaged immediately. These products have a very short shelf life, usually a few days, and are maintained by storage at temperatures between 0 and 5°C. 

Figure 3. Changes in ascorbic acid content of freshly squeezed orange juice and reconstituted orange juice concentrate during storage in refrigerator (62)...

When freshly squeezed orange juice is allowed to stand, the suspended pectic compounds ("cloud") separate and settle from the juice. This phenomenon can be prevented by heating the freshly squeezed juice to inactivate the pectin methylesterase, producing a "cooked flavor." Alternatively, additional polygalacturonase can be added to the juice (53). Cloud precipitation is caused by Ca + chelating the pectic acid produced by pectin methylesterase. 

Dimitriou. M., New Evaporator Type for the Fruit Juice Industry, Fllissiges Obst, 2, (1984) Florida Department of Citrus, Scientific Research Department, University of Florida -IFAS -CREC, 700 Experiment Station Road, Lake Alfred, Florida 33850-2299, Technical Manual, Florida Orange Juice (Commonly called Fresh-Squeezed Florida Orange Juice), Production/ Packaging/ Distribution. September 1987... 

Decio, R, Gherardi, S., Freshly Squeezed Orange Juice, Confructa Studien, 36, Nr. V/VI, 162-167, (1992)... 

Black-Eyed Suzie s (128 E. 7th St., s 212-388-0707) is famous for their organic country-style breakfasts. Fresh-squeezed orange juice with plenty of pulp and fresh peach pancakes with pure maple syrup will make you feel as if you re near Green Acres, not Times Square. 

Sanchez, M.C., Plaza, L., Ancos, B., and Cano, M.P. 2003. Effect of high-pressure processing on health-promoting attributes of freshly squeezed orange juice (Citrus sinensis L.) during chilled storage. European Food Research and Technology 216 18-22. 

A heterogeneous mixture is a mixture that does not blend smoothly throughout and in which the individual substances remain distinct. The salad dressing mixture is an example of a heterogeneous mixture. Its composition is not uniform—the substances have not blended smoothly and remain distinct. In another example, fresh-squeezed orange juice is a heterogeneous mixture of juice and pulp. 

Del Caro et al. (2004) did not see significant changes in the pH, acidity, °Brix, and dry matter of freshly squeezed juice of Shamouti oranges. Red Blush grapefruit, and Salustiana oranges during 15 days storage at 4°C. 

Collet et al. (2005) stated that the study of pectinesterase inactivation behavior is important because pectinesterase is responsible for juice cloud stability loss, is composed of several isoenzymes, and occurs naturally in orange. Freshly squeezed juice of Pera orange (Citrus sinensis) was pasteurized at temperatures of 82.5, 85.0, and 87.5°C. At least five runs with different holding times were performed for each temperature. As the isothermal curves obtained showed deviations from the expected first-order kinetics, the data was statistically treated by applying a nonlinear regression, and the estimated best fit was a three-parameter-multicomponent-flrst-order model. At 82.5°C, the isothermal curves showed a nonzero asymptote of inactivation, indicating that at this temperature the most heat-resistant... 

Polydera et al (2004) studied the inactivation kinetics of endogenous PME in freshly squeezed orange juice under high hydrostatic pressure (100-800 MPa) combined with moderate temperature (30-60 °C). PME inactivation followed first order kinetics with a residual PME activity (5-20%) at all pressure-temperature combinations used. Pressure and temperature were found to act synergistically, except in the high temperature-low pressure region, where an antagonistic effect was found. 

Decio, P. and Gherardi, S. 1992. Freshly squeezed orange juice. Confructa-Studien 36, 162-167. 

Figure 10.210 Reversed-phase chromatography in ion-suppression mode of hydrophilic organic acids in a freshly squeezed orange juice. Separator column Acclaim OA, 5 pm column dimensions 250mm x4 mm i.d. column temperature 30 °C eluent 0.1 mol/L...

Na2S04, pH 2.7 with methanesuifonic acid flow rate 0.6ml7min detection UV (210nm) sample freshly squeezed orange Juice diluted 1 2 with deionized water, OnGuard P peaks (1) malic add, (2) ascorbic add, (3) citric add, and (3) fumaric add. 

Data obtained from the sum of hesperidin and narirutin for fresh and hand-squeezed orange juices and naringin and narirutin for grapefruit juices reported in the original reference. 

Lee, H. and Coates, G. 1999. Vitamin C in frozen, fresh squeezed, unpasteurized, polyethylene-bottled orange juice a storage study. Food Chemistry, 65(2), 165-168. 

Numerous investigations on orange flavor volatiles showed that their main components are hydrocarbons [1,2,6]. Because of their high odor thresholds, however, their contribution to the overall flavor is rather low. Extensive studies on the flavor of freshly squeezed orange juice have confirmed that the overall flavor impression is predominantly caused by oxygenated... 

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