162 A S. Grandison whey cations for NH4. The whey salts are thus exchanged for ammonium bicarbonate which decomposes to NH3, CO2 and water during subsequent evaporation, the NH3 and CO2 being recovered. Jonsson and Arph(1987)compared conventional ion-exchange demineralisation of cheese whey to the Smr process and concluded that the requirement for regeneration chemicals and production of waste chemicals are much reduced in the SMR process Demineralisation by ion-exchange resins is used at various stages during the manufac ture of sugar from either beet or cane, as well as for sugar solutions produced by hydroly sis of starch. In the production of sugar from beet, the beet juice is purified by liming and carbonatation and then may be demineralised by ion-exchange(McGinnis, 1971). The carbonated juice is then evaporated to a thick juice prior to sugar crystallisation Demineralisation may, alternatively, be carried out on the thick juice which has the advantage that the quantities handled are much smaller, but is limited by the fact that diffusion rates are low at high sugar concentrations, To produce high-quality sugar the juice should have a purity of about 95%. Rousseau(1984)described the new demineralisation/ demi' process which utilises a mixed bed of weak cationic and weak anionic resins in a batchwise process to treat the thick juice(dry matter 70%0). This gives rise to a very pure juice with minimum dilution, with the bonus of a decolorisation at no extra cost. A further application in beet sugar production is the Quentin process by which the sugar level of molasses can be decreased. This is achieved by exchanging potassium and sodium ions of the juice prior to the final crystallisation, for magnesium using a strongly acidic cation exchanger. Magnesium is less molassigenic than alkali Ions Ash removal or complete demineralisation of cane sugar liquors has been described by Chen(1985).The process is carried out on liquors that have already been clarified and decolorised. so the ash load is at a minimum The use of a mixed bed of weak cation and strong anion exchangers in the hydrogen and hydroxide forms, respectively, reduces the prolonged exposure of the sugar to strongly acid or alkali conditions which would be necessary if two separate columns were used. Destruction of sucrose is thus minimised The cation and anion resins are sometimes used in their own right for dealkalisation or deacidification, respectively, Weak cation exchangers may be used to reduce the alkalinity of water used in the manufacture of soft drinks( Carney, 1988)and beer( Cristal 1983), while anion exchangers can be used for deacidification of fruit and vegetable juices(Lue and Chiang, 1989; Dechow et aL., 1985). In addition to deacidification, anion exchangers may also be used to remove bitter flavour compounds(such as naringin or imonin)from citrus juices (Johnson and Chandler, 1985). Anion or cation exchange resins are used in some countries to control the pH or titratable acidity of wine(rankin 1986: Bonorden et al., 1986)although this process is not permitted by other tradition wine producing countries. Acidification of milk to pH 2. 2, using ion-exchange during casein manufacture by the Bridel process, has also been described(Pierre and Douin 1984) Ion-exchange processes can be used to remove specific metals or anions from drinking ater and food fluids, which has potential application for detoxification or radioactive decontamination. For example, procedures have been described for the removal of lead Brajter and Slonawska, 1986), barium and radium(Snoeyink et al., 1987), aluminium162 A. S. Grandison whey cations for NH;. The whey salts are thus exchanged for ammonium bicarbonate which decomposes to NH3, C02 and water during subsequent evaporation, the NH, and C02 being recovered. Jonsson and Arph (1 987) compared conventional ion-exchange demineralisation of cheese whey to the SMR process and concluded that the requirement for regeneration chemicals and production of waste chemicals are much reduced in the SMR process. Demineralisation by ion-exchange resins is used at various stages during the manufac￾ture of sugar from either beet or cane, as well as for sugar solutions produced by hydroly￾sis of starch. In the production of sugar from beet, the beet juice is purified by liming and carbonatation and then may be demineralised by ion-exchange (McGinnis, 197 1). The carbonated juice is then evaporated to a thick juice prior to sugar crystallisation. Demineralisation may, alternatively, be carried out on the thick juice which has the advantage that the quantities handled are much smaller, but is limited by the fact that diffusion rates are low at high sugar concentrations. To produce high-quality sugar the juice should have a purity of about 95%. Rousseau (1984) described the ‘new demineralisation/demi’ process which utilises a mixed bed of weak cationic and weak anionic resins in a batchwise process to treat the thick juice (dry matter 70%). This gives rise to a very pure thick juice with minimum dilution, with the bonus of a decolorisation at no extra cost. A further application in beet sugar production is the Quentin process by which the sugar level of molasses can be decreased. This is achieved by exchanging potassium and sodium ions of the juice prior to the final crystallisation, for magnesium using a strongly acidic cation exchanger. Magnesium is less molassigenic than alkaline ions. Ash removal or complete demineralisation of cane sugar liquors has been described by Chen (1985). The process is carried out on liquors that have already been clarified and decolorised, so the ash load is at a minimum. The use of a mixed bed of weak cation and strong anion exchangers in the hydrogen and hydroxide forms, respectively, reduces the prolonged exposure of the sugar to strongly acid or alkali conditions which would be necessary if two separate columns were used. Destruction of sucrose is thus minimised. The cation and anion resins are sometimes used in their own right for dealkalisation or deacidification, respectively. Weak cation exchangers may be used to reduce the alkalinity of water used in the manufacture of soft drinks (Carney, 1988) and beer (Cristal, 1983), while anion exchangers can be used for deacidification of fruit and vegetable juices (Lue and Chiang, 1989; Dechow et al., 1985). In addition to deacidification, anion exchangers may also be used to remove bitter flavour compounds (such as naringin or limonin) from citrus juices (Johnson and Chandler, 1985). Anion or cation exchange resins are used in some countries to control the pH or titratable acidity of wine (Rankine, 1986; Bonorden et al., 1986) although this process is not permitted by other traditional wine producing countries. Acidification of milk to pH 2.2, using ion-exchange during casein manufacture by the Bride1 process, has also been described (Pierre and Douin, 1984). Ion-exchange processes can be used to remove specific metals or anions from drinking water and food fluids, which has potential application for detoxification or radioactive decontamination. For example, procedures have been described for the removal of lead (Brajter and Slonawska, 1986), barium and radium (Snoeyink et al., 1987), aluminium