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FAIR-CT95-1048
Valorising of Lactose by Enzymatic Conversions to Compounds with Application in the Food and Non-Food Industries |
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Type of Project | Shared Cost |
| Contract No | FAIR-CT95-1048 | |
| Total Cost | 1,803,053 ECU | |
| EC Contribution | 1,564,053 ECU | |
| Start Date | 01/11/1996 | |
| Duration | 36 Months |
Valorising of lactose by enzymatic conversions to compounds with application in the food and non-food industries
Objectives
One of the most significant problems with regard to economics and environmental impact faced by the dairy industries is the disposal of lactose in whey permeates. Lactose is a low- value sugar accounting for up to 75% of the total dry material in whey and accumulates in annual quantities of approximately 1.2 million tons worldwide without many profitable routes for the direct utilisation being available. Lactose itself has a very weak marketing potential due to several reasons, lactose intolerance of the consumers being probably the most important. As a consequence, a project was started to develop uses for lactose by enzymatic conversion processes to products more valuable than the parent compound.
Technical Approach
First the project is aimed at improving existing chemical or biotechnical routes to lactose-derived products in terms of productivity and process economy. Lactose hydrolysis (using enzymes from thermophilic microorganisms) to yield a mixture of glucose and galactose, which is more suitable for food applications than lactose, and classic primary conversions of lactose will be targeted. The products of the latter are lactitol (a low cariogenic sweetener), lactobionic acid (a compound that is known to be useful in medicine, but also in food products due to its sweet-sour taste), and lactulose (a bifidogenic component). The enzymatic approach to these products is characterised by two aspects of novelty: the use of coenzyme dependent catalysts for redox processes of lactose conversion and the emerging unit operation of charged nanofiltration membrane technology concerning coenzyme retention. Tasks within the process development comprise:
These will lead to technical applications with a high degree of probability.
A second major goal of the project is to prepare new products from lactose while exploiting the entire range of synthetic potential of the biocatalysts such as activity- or specificity-tuned glycosidases, esterases and others. Employing the respective enzymes under conditions that do not occur in nature (such as in organic solvents), a number of interesting compounds including esters, polymers, oligosaccharides or glycosides will be made. The novelty aspects within these tasks include the optimisation of reaction conditions and routes to completely new products with expected applications in food and non-food industries such as surfactant manufacture.
As a third goal the possible and improved applications of the products prepared in the project will be targeted, and special reference will be given to assess the effect of these products on the growth promotion of probiotic organisms. These organisms are known to have beneficial effects on human health and well being. As a result of these studies the most promising lactose-derived compounds will be selected for the development of new functional food products.
The long-term objective is to improve the competitiveness of the EU in the versatile area of lactose valorisation, especially by means of enzyme technology, which will help the EU to take the lead in launching novel lactose-based products on the world market. The efficient conversion of the low-value compound lactose into (much) more valuable products could indeed serve as the basis for new industry in the future. In addition, for two economic reasons, the project and the processes to be developed therein will add to novel green technologies. First, with better options to utilise lactose being available, the large biological oxygen consumption of today's effluents from the dairy industries will certainly be reduced. Second, lactose-derivatives will be biodegradable and could - at least with regard to the surfactant industry - be more environmentally compatible than current products on the market.
Results To Date
An improved dialysis membrane reactor system was developed for lactose hydrolysis and reduction of the sugar content to less than 20% (to serve lactose intolerant consumers).
This 100 litre scale process is now being upscaled to about 1000 tons skimmed milk powder per year together with Lactoprot (an Austrian lactose company). For improved sterility, commercial mesphilic ß-galactosidases will be replaced soon by ß-glycosidases from thermophiles (Sulfoobus sofataricus, Pyrococcus furiosus). S.s. ß-gly and P.f. ß-gly cloned and expressed in Escherichia coli where characterised and compared, e.g. concerning long-term stability and oligosaccharide formation at 70oC.
Several other enzymes transforming lactose or its derivatives (aldose reductase, xylitol-, sorbitol-, cellobiose-dehydrogenase) by cofactor-dependent oxidoreduction reactions were screened, fermented, purified, characterised and partially expressed by recombinant E. coli. Process development for lactobionic acid (100g scale), galactitol and tagatose is underway. Lactitol and lactulose are other targets. Some of these basic derivatives were further transformed by lipases, esterases or ß-glycosidases in the presence of organic solvents. After careful optimisation of reaction conditions some compounds (esters, glycosides) are now available on 100 mg scale.
A large number of prebiotic sugar (including lactose) derivatives were tested concerning their influence on the growth of bifidogenic and other intestinal microbial strains in order to develop new functional food products.
Enzymatic transformation of lactose
Contacts
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Participant
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