Frozen concentrated citrus juices

Technological developments in high vacuum evaporation techniques have been responsible for the rapid growth of the domestic citrus industry. These techniques were developed and refined, for the most part, during World War II and they made possible the manufacture and production of many perishable foods and medicines. Most notable for the domestic citrus industry was the development of frozen concentrated citrus juices which was made possible by the development of these high vacuum evaporators... 

FCOJ and other frozen concentrated citrus juices are produced by the process outlined in Figure 4. Prior to evaporation the process includes extraction, finishing, and blending. In the evaporator, the juice may be concentrated to 45°Brix (% soluble solids) or higher and, as a matter of routine practice, most of the evaporator pumpout (concentrate) is at 65-68°Brix. 

A typical fruit juice evaporation system using the heat pump cycle is shown (PI, Cl), which uses low-temperature ammonia as the heating fluid. A frozen concentrated citrus juice process is described by Charm (Cl). The process uses a multistage falling-film evaporator. A major fault of concentrated orange juice is a flat flavor due to the loss of volatile constituents during evaporation. To overcome this, a portion of the fresh pulpy juice bypasses the evaporation cycle and is blended with the evaporated concentrate. 

The use of citrus fruit, especially oranges, dramatically increased in the U.S. after World War II (1 ) because of the introduction of frozen concentrated orange juice (FCOJ) to the market. Citrus fruits, being subtropical products, did not enjoy the popularity of other fruits, e.g. apples, because the locality of production were usually not near the world population centers and because of perishability of citrus fruits during storage. 

There is much that can be said in favor of the consumption of fresh fruits and vegetables in the daily diet. In much of the world, citrus is consumed primarily as the fresh fruit, but in the United States processed products are consumed as the major source of citrus in the diet. The main staple of processed citrus juices in the U.S. is frozen concentrated orange juice (FCOJ). 

Frozen concentrated orange juice began to capture a real segment of the citrus market in 1948, and since then, its presence has been a dominant contributing factor to the increasing per capita consumption of citrus juices worldwide. 

Processed orange products accounted for the usage of about 81% of the domestic orange crop between the years 1973 and 1978, as can be seen in Table II. Frozen concentrated orange juice in that period was by far the major product of the U.S. citrus industry, which is concentrated in 4 states Florida, California, Texas, and Arizona, with Florida being the dominant factor in the industry. 

Frozen concentrated orange juice (FCOJ) is by far the most widely distributed of the processed citrus products. First marketed in the mid-1940 s, it has grown in consumer acceptance until the present day, and to the point where its volume consumption exceeds the combined total for all other processed citrus products. 

The presence of surface or floating juice sacs may significantly affect sensory evaluation of citrus juices. Amount of floating pulp in any particular retail product is primarily dependent on corporate specifications as per their beliefs. When testing frozen concentrated citrus products containing signifi-... 

The Florida Department of Citrus rules (4 ) prohibit the addition of any PW to frozen concentrated orange juice (FCOJ). The U. S. regulations, while not as strict, prohibit addition of PW beyond that obtained from the particular batch of fruit from which the juice was obtained (5j. Since Florida produces most of the FCOJ in the United States, this type of adulteration is a national as well as a state problem. 

Flavor changes that occur in citrus juices are the result of heat input into the product over time i.e., they are a function of temperature and time. It is for this reason that canned and bottled juices are generally less preferred by consumers than other processed citrus juices, e.g., frozen concentrates or chilled juices. The canned juices receive more heat input during pasteurization and they remain at relatively high temperatures for extended periods of time because they are discharged from the water coolers at temperatures near 40°C to facilitate drying and to inhibit rusting of the cans. It is well known that the rate of flavor deterioration increases with temperature, so canned juices are stored at a temperature as low as is economically practical before distribution at the retail level to extend their shelf life as much as possible. 

Of course, identical reconstitution methodology could be applied to frozen concentrated grapefruit or other citrus juices as well as for FCOJ as discussed above. 

Yet another valuable avor product of citrus fruits is the essence oil. The favored method for the transport of citrus juice is in the form of a frozen juice concentrate. The fruit juice is partly... 

Yet another valuable flavor product of citrus fruits is the essence oil. The favored method for the transport of citrus juice is in the form of a frozen juice concentrate. The fruit juice is partly dehydrated by distilling off under vacuum the greater part of the water and frozen. Distilling off the water results in significant losses of the desirable volatiles responsible for the aroma of the fruit. These volatiles are captured in several cold traps and constitute the aqueous essence or essence oil that has the typical fruity and fresh fragrance, but slightly less aldehydic than that of the oil. This oil is used to enhance the flavor of the reconstituted juice obtained by thawing and dilution with water of the frozen concentrate. 

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