ABSTRACT
Oranges, and citrus in general, are harvested for about 6-9 months; nonetheless the fresh fruit is not literally available year round in the United States, and so it has to be processed and preserved. Oranges change in their sugar and acid content, flavor, and color with time of the year, with geographical area, varieties, and many other variables. Frozen concentrated orange juice is a concentrated product in that the water is removed and solids are increased. Orange processing teaches some lessons that can be extended to other commodities in which heat-sensitive, volatile characteristic flavors are significant. The juice is heated to inactivate an enzyme called methyl pectin esterase, which would decompose the naturally occurring pectin in orange juice that helps keep orange juice cloudy. Fresh orange juice initially is cloudy, but if allowed to stand enzyme modification of the pectin will allow the pulp to settle to the bottom, leaving a clear juice (serum) on the top.
