Food industry electrodialysis application

Bazinet, L., Lamarche, F., Labrecque, R., Toupin, R., Boulet, M., and Ippersiel, D. 1997. Electroacidification of soybean proteins for the production of isolate. Food Technol. 51(9), 52-56, 58, 60. Bazinet, L., Lamarche, F., and Ippersiel, D. 1998. Bipolar-membrane electrodialysis Applications of electrodialysis in the food industry. Trends in Food Sci. Technol. 9, 107-113. 

The two water desalination applications described above represent the majority of the market for electrodialysis separation systems. A small application exists in softening water, and recently a market has grown in the food industry to desalt whey and to remove tannic acid from wine and citric acid from fruit juice. A number of other applications exist in wastewater treatment, particularly regeneration of waste acids used in metal pickling operations and removal of heavy metals from electroplating rinse waters [11]. These applications rely on the ability of electrodialysis membranes to separate electrolytes from nonelectrolytes and to separate multivalent from univalent ions. 

Bazinet L, Lamarche E, and Ippersiel D. Bipolar-membrane electrodialysis An application of electrodialysis for the food industry. Trends Food Sci. Tech. 1998 9 107-113. 

The effect of the cost of the ion exchange membrane on the total cost of electrodialysis or electrolysis is large because the membrane is relatively expensive. The lifetime of the membrane depends on the purpose and conditions of electrodialysis or electrolysis. A membrane for the electrodialytic concentration of seawater to produce sodium chloride has a lifetime of over 10 years, and that in the chlor-alkali membrane process, which is operated at ten times or more higher current density than that of seawater concentration, is over 5 years. However, in applications for food industries, the lifetime of the membrane is relatively short due to periodical sanitary cleaning of the electrodialyzer by acid or alkali solution, and sometimes oxidizing agents. 

Many papers on continuous fermentation using electrodialysis have been reported.34 If ionic products produced in the fermentation broth amino acids, carboxylates, etc. are removed from the broth by electrodialysis, continuous fermentation becomes possible. The diffusion behavior of organic acids, such as, acetic, propionic, lactic, tartaric, oxalic, or citric acid through cation78 and anion79 exchange membranes has been studied in detail in connection with the removal of organic acids from the fermentation broth, and in applications in the food industry. 

Several other applications of electiodialysis in the pharmaceutical industry have been studied on a laboratory scale [51]. Most of these applications are concerned with desalting solutions containing active agents which have to be separated, purified, or isolated from certain substrates [52]. Here, electrodialysis is often in competition with other separation procedures such as dialysis, solvent extraction, etc. In many cases, electrodialysis is the superior process as far as economics and the quality of the product is concerned. Especially the separation of amino acids and other organic acids by electrodialysis seems to be of interest to the pharmaceutical and chemical industry [53]. However, the deionization of cheese whey with an installed capacity of more than 35,000 square meters of membrane area for the production of more than 150,000 tons of desalted lactose per year is economically by far the most important application of electrodialysis in the food industry today. 

Bazinet, L., Lamarche, F., and Ippersiel, D. (1998) Bipolar membrane electrodialysis Applications of electrodialysis in the food industry. Trends in Food Science and Technology 9, 107-113. 

The need for high purity in a separations process is common in many industries semiconductor manufacture, pharmaceuticals processing, and the foods industry, as weil as in many cases of more-conventional chemical processing. It is also very important in separation processes that are oriented to cleaning gas, liquid, and solid streams for environmental purposes. The low concentrations required of many environmentally significant compounds prior to discharge from a chemical plant have created a need for a new class of separation methods and have focused attention on many techniques that often have been ignored. Adsorption, ultraflitration, electrostatic precipitation, reverse osmosis, and electrodialysis are just a few examples of separation processes in which there has been an increased level of interest partly because of their potential in environmental applications. 

Electrodialysis is used widely to desalinate brackish water, but this is by no means its only significant application. In Japan, which has no readily available natural salt brines, electrodialysis is used to concentrate salt from seawater. Tbe process is also used in the food industry to deionize cheese whey, and in a number of pollution-control applications. 

Electrodialysis is by far the largest use of ion exchange membranes, principally to desalt brackish water or (in Japan) to produce concentrated brine. These two processes are both well established, and major technical innovations that will change the competitive position of the industry do not appear likely. Some new applications of electrodialysis exist in the treatment of industrial process streams, food processing and wastewater treatment systems but the total market is small. Long-term major applications for ion exchange membranes may be in the nonseparation areas such as fuel cells, electrochemical reactions and production of acids and alkalis with bipolar membranes. 

This review summarizes the monopolar and BPM principles of operation. Moreover, this review presents shortly the main applications in chemical processing, pollution control, and resource recovery, and details the specific applications of electrodialysis with BPMs to food and bio-industries. 

S. Miyagi, Desalination by electrodialysis in the cane raw sugar factory, Int. Sugar J., 1985, 87, 3-10 T. Kokubu, T. Yamauchi and S. Miyagi, Application technology of electrodialysis in sugar industry, Food Ind., 1983, 27, 26-31. 

The technically and economically most important electrodialytical process used for the separation of ionic components from an aqueous solution is conventional electrodialysis. The main application of electrodialysis is the desalination of brackish water. However, other uses, especially in the food, drug, and chemical process industry as well as in biotechnology and waste water treatment, have recently gained a broader interest. In its basic form electrodialysis can be utilized to perform several general types of separations, such as the separation and concentration of salts, acids, and bases from aqueous solutions, or the separation of monovalent ions from multiple charged components, or the separation of ionic compounds from uncharged molecules. 

The use of electrodialysis in food, drug, and chemical industries has been studied quite extensively in recent years. Several applications have considerable economic significance and are already well established today. One is the demineralization of cheese whey [46]. Normal cheese whey contains between 5.5 and 6.5 % of dissolved solids in water. The primary constituents in whey are lactose, protein, minerals, fat and lactic acid. Whey provides an excellent source of protein, lactose, vitamins, and minerals, but in its normal form it is not considered a proper food material because of its high salt content. With the ionized salts substantially removed, whey provides an excellent source for the production of babyfood. The partial demineralization of whey can be carried out quite efficiently by electrodialysis. 

Overall the electrodialysis industry has experienced a steady growth since it made its appearance as an industrial scale separation process about 15 years ago and new areas of application in the food and chemical process industry are gaining interest rapidly. 

Electrodialysis 1. Desalination of brackish water 2. Production of table salt 3. Waste water treatment 4. Concentration of RO brines 5. Applications in the chemical, food, and drug industries... 

Ultraflltration is also used to fractionate and concentrate proteins from potato processing wastewaters. Other protein wheys can be processed by reverse osmosis. Electrodialysis is used for a number of applications in the food and beverage industry, including deionization or deacidification of fruit juices, wines and, in the dairy industry, milk and whey. It often competes directly with ion exchange processes. 

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