A process for the demineralization of whey or a liquid based on whey and for producing an acid mixture and a base mixture useful in food industries
The invention relates to a process for removing by electrolysis at least a portion of salts contained in whey or a liquid based on whey while producing an acid mixture and a base mixture useful in food industries. The invention is further concerned with products obtained by means of the process, particularly with an acid mixture and a base mixture useful in food industries.
The high salt content of whey obtained as a side product in the production of cheese and casein is the main reason why whey cannot be used in foodstuffs. However, demineralized whey powder has many uses in baby foods, ice-cream and bakery industries. Demineralization of whey has long been carried out by electrodialysis and ion exchange. Such techniques have also been combined for improving the efficiency and economy of the demineralization process (see e.g. British Patent Specificiation 1,583,814). It is typical of all the techniques mentioned above that the salts contained in whey as well as small amounts of the other whey solids, i.e. lactose and proteins, get into the waste water. Waste water treatment increases considerably the cost of the demineralization process and may even prevent the introduction of the process. Since waste waster regulations are becoming increasingly strict, attempts have been made to solve this problem. Recently, a new demineralization process based on ion exchange has been developed in which part of the regeneration chemicals can be reused (see e.g. U.S. Patent Specification 4,159,350). However, this process, to, produces considerable amounts of waste water, so there is still a need of new techniques by means of which waste water problems are avoided or at least substantially reduced.
On the other hand, it has long been known that a salt solution can be rendered to a corresponding acid and base in an electrolytic cell divided into four compartments by means of cation and anion exchange membranes (see e.g. French Patent Specification 1,324,549). This techique, however, has been applied only to the treatment of pure inorganic and organic salts. Electrolysis as such has also been used experimentally in the treatment of milk (see e.g. British Patent Specificiation 2,100,289 A); however, the cell structure described in the examples has thereby comprised two or three compartments and the aim has not been to demineralize milk but to adjust its pH.