Membrane fruit juice

The most significant application of reverse osmosis has been in the field of desalination to produce drinking water. Other important apphcations include the treatment of industrial waste water, concentration of fruit juices, and concentration of weak solutions such as aqueous ethanol [3-6]. The rest of the chapter will focus almost entirely on semi-permeable membranes used for reverse osmosis based applications. We chose this focus in view of the importance of reverse osmosis as a rather efficient separation technique for separating a wide range of solutions, especially very dilute solutions—which are usually notoriously difficult to handle using conventional techniques such as distillation. 

UF is used to clarify various fruit juices (apple, grape, pear, pineapple, cranberry, orange, lemon) which are recovered as the permeate [Blanch et al., AlChE Symp. Ser. 82, 59 (1986)]. UF has also been used to remove pigments and reducing browning in wine production [Kosikowski in Membrane Separations in Biotechnology, McGregor (ed.), Marcel Dekker, New York, 1986]. 

There is increasing interest in the use of specific sensor or biosensor detection systems with the FIA technique (Galensa, 1998). Tsafack et al. (2000) described an electrochemiluminescence-based fibre optic biosensor for choline with flow-injection analysis and Su et al. (1998) reported a flow-injection determination of sulphite in wines and fruit juices using a bulk acoustic wave impedance sensor coupled to a membrane separation technique. Prodromidis et al. (1997) also coupled a biosensor with an FIA system for analysis of citric acid in juices, fruits and sports beverages and Okawa et al. (1998) reported a procedure for the simultaneous determination of ascorbic acid and glucose in soft drinks with an electrochemical filter/biosensor FIA system. 

Figure 3.17. A typical fruit juice plant using Membralox ceramic membrane filters (approx. 100 m membrane area). (Courtesy MEMBRAFLOW Filter systems Germany).

The removal of macromolecules by ultrafiltration has often been used in the production of clear fruit juices and wine (Girard and Fukumoto, 2000). This treatment removes both proteins and polysaccharides. Ultrafiltration through a 10,000 Da cut-off membrane has been shown to stabilize wines against haze formation (Flores, 1990). 

Girard, B. and Fukumoto, L. R. (2000). Membrane processing of fruit juices and beverages A review. Crit. Rev. Biotechnol. 20, 109-175. 

Schmid et al. used the same principle to develop sensors to be incorporated into FI systems for the determination of ascorbic acid in fruit juices [38] and that of lactic acid in dairy products [39]. The membrane used in both applications consisted of decacyclene dissolved in silicone rubber that was treated similarly as the membrane in glucose sensors (Fig. 3.4.B). The oxygen optrode was coated with a sheet of carbon black as optical insulation in order to protect it from ambient light or intrinsic sample fluorescence. Ascorbic acid oxidase or lactic acid oxidase was immobilized by adsorbing it onto carbon black and cross-linking it with glutaraldehyde. The FI system automatically buffered and diluted the food samples, thereby protecting the biosensor from a low pH and interferents. 

Figure 2.8 Schematic diagram of the concentration of fruit juice by vapour transport across a porous Teflon membrane.

Isotopic distribution within an element will vary between living organisms depending on the biosynthetic pathways that lead to its formation. Furthermore, the rate at which a molecule crosses cellular membranes will depend on the molecule s isotopic distribution. Hence, detectable differences in isotopic composition can be observed in the products formed. Detection of adulterated vegetable oils, flavourings and fruit juices, as well as the study of metabolism in plants and numerous biomedical applications, use isotopic abundance as a tool. For example, the... 

Gajovic et al. [64] L-malate Fruits, fruit juices, ciders and wines NAD(P)+-dependent L-malate dehydrogenase oxaloacetate decarboxylating with salicylate hydroxylase (SHL)/ in gelatine membrane sandwiched between a dialysis membrane and a PET membrane Clark-electrode ... 

Prodromidis et al. [35] Citric acid Fruits, juices and sport drinks Citrate lyase (in solution), oxaloacetate decarboxylase and pyruvate oxidase/ sandwiched between a cellulose acetate membrane and a protective polycarbonate membrane H202 probe (Pt electrode) ... 

Citrus fruits, especially certain of their component parts, constitute one of the richest sources of pectin. On a dry weight basis, as much as 30% of orange fruit albedo may be pectin (8). The rag, comprising the fruit core and segment membranes after juice extraction, is also a rich source. Since pectin is a cell wall component, it follows that comparatively little would be present in juice expressed from fruit. For example, concentrations ranging from 0.01 to 0.13% in orange juice have been reported (15). Much of this would be present as cell wall fragments and particulate material in juice pulp and cloud. 

When dealing with acid whey, and lactate removal is a priority task, it is possible to resort to a three-compartment configuration (Figure 13), obtained by assembling a series of two anionic membranes and a single cationic one (Williams and Kline, 1980). By feeding the compartments limited by two anionic membranes with acid whey and the other two adjacent compartments with a brine solution and an alkaline one, respectively, it is possible to remove selectively lactate anions from the product and replace them with hydroxyl ions. This procedure is also suggested to reduce the acidity of several acidic fruit juices without any chemical addition (Section III.E). 

FIG. 17 Schematic layout of a three-compartment ED stack for the deacidification of fruit juices a, anionic membrane c, cationic membrane R , generic anion X+, generic cation. 

Figure 6.24 Ultrafiltration flux in apple juice clarification as a function of the volumetric feed-to-residue concentration factor. Tubular polysulfone membranes at 55 °C [27]. Reprinted from R.G. Blanck and W. Eykamp, Fruit Juice Ultrafiltration, in Recent Advances in Separation Techniques-III, N.N. Li (ed.), AIChE Symposium Series Number 250, 82 (1986). Reproduced by permission of the American Institute of Chemical Engineers. Copyright 1986 AIChE. All rights reserved...

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. 

Figure 10.17 Flow schematic of electrodialysis systems used to exchange target ions in the feed solution, (a) An all-cation exchange membrane stack to exchange sodium ions for calcium ions in water softening, (b) An all-anion exchange membrane stack to exchange hydroxyl ions for citrate ions in deacidification of fruit juice...

Integrated Membrane System for Fruit-Juices Industry... 

Integrated membrane processes are today proposed also in the dairy, food, and fruit-juices industries. 

Figure 12.7 Scheme of an integrated membrane process for fruit-juice concentration [26],... 

The interactions between pectins and sugars (rhamnose, arabinose, and galatose) are principally responsible for the high turbidity and viscosity of fruit juice. Pectinases immobilized in membranes are used to reduce the viscosity of fruit juice [12, 13]. 

Integrated Membrane Processes for Water Desalination 266 Integrated Membrane Process for Wastewater Treatment 271 Integrated Membrane System for Fruit-Juices Industry 274 Integrated Membrane Processes in Chemical Production 276 Conclusions 281 References 281... 

Osmotic distillation also removes the solvent from a solution through a microporous membrane that is not wetted by the liquid phase. Unlike membrane distillation, which uses a thermal gradient to manipulate the activity of the solvent on the two sides of the membrane, an activity gradient in osmotic distillation is created by using a brine or other concentrated solution in which the activity of the solvent is depressed. Solvent transport occurs at a rate proportional to the local activity gradient. Since the process operates essentially isothermally, heat-sensitive solutions may be concentrated quickly without an adverse effect. Commercially, osmotic distillation has been used to de-water fruit juices and liquid foods. In principle, pharmaceuticals and other delicate solutes may also be processed in this way. 

MEMBRANE FILTRATION. Membrane filter cartridges are seldom used in fruit juice technology, as hot-filling is the common practice and prior membrane filtration is therefore unnecessary. These filters can only be used after fine filtration, as otherwise the membrane is immediately clogged up. 

Clarification of other fruit juices. Clarification of cranberry juice has also been practiced commercially using ceramic membranes recently. Through a series of tests with alumina microfilters, Venkataraman et al. [1988] determined that the optimal pore diameter is about 0.45 pm with respect to the permeate flux and the clarity of the... 

Membrane contactors can be used in osmotic distillation process to transfer water vapor, as discussed in Section 2.8. Such a process has been investigated as a means of concentrating fruit juice [58] using concentrated brine as the receiving phase for water vapor. A photograph of a pilot system is shown in Figure 2.15. 

FIGURE 2.15 (See color insert following page 588.) Membrane contactor for fruit juice concentration using membrane distillation process. 

Alves VD and Coelheso IM, Low temperature membrane processes for fruit juice concentration. Euromembrane 2004, Hamburg, Germany, September 28-October 1, 2004. 

Pereira CC, Rufino JRM, Habert AC, Noberga R, Cabral LMC, and Borges CP. Aroma compounds recovery of tropical fruit juice by pervaporation Membrane material selection and process evaluation. J. Food Eng. 2005 66(l) 77-87. 

Jiao B, Cassano A, and Drioli E. Recent advances on membrane processes for the concentration of fruit juices a review. J. Food Eng. 2004 63 303-324. 

Howell JA. Future of membranes and membrane reactors in green technologies and for water reuse. Desalination, 2004 162(10) 1-11. Noronha M, Britz T, Mavrov V, Janke HD, and Chmiel H. Treatment of spent process water from a fruit juice company for purposes of reuse Hybrid process concept and on-site test operation of a pilot plant. Desalination, 2002 143(2) 183-196. 

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