Citrus-processing industry

Data from a statistical report ( ) indicated that over one million tons of dried citrus pulp and pellets were produced during a recent season from the Florida crop, which was about 70% of total U. S. citrus production. This by-product is important to the function of the citrus processing industry and to many livestock producers who use it as a cattle feed supplement. 

Mamma, D., Kourtoglou, E., and Christakopoulos, P. (2008). Fungal multienzyme production on industrial by-products of the citrus-processing industry. Bioresour. Technol. 99,... 

Limonene is an important by-product of the citrus processing industry. Potentially, this compound can be used as a substrate for the production of several terpenoids with important flavour characteristics, such as menthol, carvone and dihydrocarvone (Fig. 1). 

In order to achieve maximum recovery of oil, the citrus processing industry applies several techniques that increase the yield. These include the following ... 

The main renewable resource for L-carvone is spearmint oil (Mentha spicata), which contains up to 75% of this flavour chemical. There also exists a synthetic process for the manufacturing of L-carvone, which is based on (-t)-limonene, which is available as a by-product of the citrus juice industry as a major component of orange peel oil (Scheme 13.4). The synthesis was developed in the nineteenth century and starts with the reaction of (-t)-limonene and nitrosyl chloride, which ensures the asymmetry of the ring. Treatment with base of the nitrosyl chloride adduct results in elimination of hydrogen chloride and rearrangement of the nitrosyl function to an oxime. Acid treatment of the oxime finally results in l-carvone. 

During industrial citrus processing, a part of the essential oil passes to the juice, depending on the extraction method, and contributes to the aroma. In the juice, essential oils are present in the range of 0.0005-0.004%, and these levels can increase to 0.01-0.1 during extraction due to contamination from the flavedo (Primo, 1997). Modem juice extraction methods tend to minimize oil contamination. 

Juice extraction represents 55% (w/w) of the initial weight of oranges, whereas the essential oils and essences extracted constitute only 0.2-0.22% (Sinclair, 1984). The citrus juice industry can recover essential oils from different intermediate process steps to obtain limonene or crude essences. In Figure 5.2, the different possibilities for obtaining essential oils with different properties are summarized (Girard and Mazza, 1998 Braddock, 1999). 

Uckoo, R.M., Jayaprakasha, G.K., and Patil, B.S. 2013. Hyphenated flash chromatographic separation and isolation of fiirocoumarins and polymethoxyflavones from byproduct of citrus juice processing industry. Separation Science and Technology, 48, 1467-1472. 

Cold-pressed essential oils from the peel are some of the most important by-products recovered during the processing of Citrus fruits. The presence of limonene in the aqueous discharges, with its antimicrobial activity [1], decreases the effectiveness of the waste treatment system and increases the time necessary for the biological breakdown of the organic matter produced in the peel oil recovery system [2,3]. Additional recovery of essential oils from waste water would increase industry s returns and reduce the pollution problems associated with the disposal of waste water [4,5]. Several methods for reducing the levels of residual essential oils in the aqueous effluent have been developed over the years [6-11]. 

The two pinenes are obtained from Crude Sulfate Turpentine (CST), which is a side product of the sulfate cellulose process from pine trees. Limonene is present in orange and lemon peels [which provide different enantiomers/ )], and is a cheap by-product of the citrus industry. 

Citric acid, which prior to 1922 was made entirely from citrus fruits and mainly in Italy, is now produced almost exclusively by the fermentation of sucrose by means of a mold, Aspergillus niger. At first pure sucrose was used for this process but more recently molasses has been used instead. Practically the whole of the world production of citric acid is used as such in medicinal preparations, in making soft drinks and in certain foods. The textile industries use small amounts, and it is also... 

Were it not for the processing of citrus fruits, this rich source of nutritious food, in the forms of juices and drinks, would be available to us for only limited periods of time throughout the course of any year. Processing techniques practiced today in the citrus industry ensure the availability of a continuous supply of citrus juices and their allied products to people in all regions of the United States and, indeed, in many parts of the world. 

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. 

Canned and bottled citrus juices are examples of products that are packed aseptically, and these processes have been used in the industry for many years. One of the newer processes for aseptic packaging employs a paperboard package that is sterilized with hydrogen peroxide prior to the form, fill, and seal operation. This process, developed by Tetra Pak Ab of Lund, Sweden, is in use in many parts of the world, but it has not yet been approved by the U.S. Food and Drug Administration for domestic use. 

J.A. Zang, Sweetening Citrus Juice in Membrane Process for Industry, Proc. Southern Res. Inst. Conf. 35 (1966). 

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