Development of solid-phase biocatalyst and bioreactor for elimination of glucose content of egg white in a technology of continuous regime

Contract Number: OMFB 02345/2000

Starting date: 01/07/2000

Duration: 28 months

OM contribution: 12 000 thousand Ft

Acronym: Glucose elimination from egg white in biocatalytic way

Background

Egg white - as stock of the food industry - is released currently in powder form, after drying. Beyond that, in the member states if European Union, it is a general practice to remove the glucose content of white (0.4 %) before drying. In this way, caramel formation - consequently, the browning of the product - can be avoided. Accordingly, the storage stability of the egg white powder can be enhanced considerably, too.

In the known technologies, the glucose content of egg white is oxidized by the help of soluble glucose oxidase or is eliminated by microbes. The disadvantage of the prior procedures is that the inactivated enzyme as extraneous protein is remained in the egg white product. It would be more advisable if glucose oxidase was used in immobilized form. In this way, enzyme would be separable from the egg white after the treatment. To the best of our knowledge, such industrial process does not exist.

In our country, there is absolutely no industrial-scale glucose elimination from egg white, although the glucose-free egg powder would be exportable, moreover, the Hungarian customers have expressed their claim to the product, too. Consequently, the glucose-free egg powder would be sold at considerably higher price than the normal one.

SÁTO Ltd., the largest egg powder producing firm in Hungary has launched development activity with the final aim to create a technology for glucose-free egg powder production in industrial scale. The managers and technical experts of the form became very well experienced in the egg powder production in the last 10 years. At the co-operation partner, Research Institute of Chemical and Process Engineering of University Kaposvár, in its Department of Bioreaction Engineering, numerous excellent theoretical as well as practical results arose in the field of study and application of immobilized biocatalysts and multiphase bioreactors, in the past 15 years.

OBJECTIVES

After immobilizing commercial food grade glucose oxidase enzyme onto suitably selected particulate solid support, a solid phase biocatalyst of sufficiently high specific activity and high stability is to be formed. The catalyst is to be operated in continuous regime in a column bioreactor of type to be developed by our group, so a glucose-free egg white liquor producing technology is to be created.

The accomplishment of the goals is profitable because the expectable results imply a novelty not only in Hungary but they represent considerable steps of international significance concerning the development activities in the field of industrial application of biological catalyst. The most important benefit of the R+D work is that after the glucose-free egg white liquor formation, enzyme protein does not pollute the food stock, on the other hand, the new process is carried out in up to date continuous operation regime.

Description

• Elaboration of a method for preparation of immobilized glucose oxidase biocatalyst of activity: at least 5 U/g dry support, of half time: at least 6 moths;

• Elaboration of a method for bubble-free oxygen transfer to egg white liquor. The rate of oxygen saturation should be minimum 20% / min (at 30 °C, 1 bar);

• Determination of the structure of a pilot-scale bioreactor (useful volume 45 dm³), appropriate to oxidation by immobilized glucose oxidase, suitable for continuous regime, too;

• Set-up of an apparatus for production of particles of immobilized biocatalyst (total volume 15-20 dm³), preparation of the biocatalyst particles;

• Set-up of the reactor for glucose elimination and its auxiliary devices; operational and experimental tests. The minimum capacity of the technology is 20-25 reactor volume/day glucose-free egg white liquor (final glucose content < 0,02 g/ dm³).

Current situation

• Combined adsorptive + covalent immobilization method has been elaborated. The productivity of glucose oxidase (immobilized onto a resin on the basis of the method) is higher than it is specified. The stability of the biocatalyst is in accordance with the book;

• Bubble-free oxygen feeding method has been elaborated using clean O₂ gas through a porous surface. The specified saturation rate has been achieved;

• 15 dm³ immobilized glucose oxidase has been produced by means of a special mechanically mixed fluidized-bed apparatus.

• A three-stage fluidized-bed pilot scale bioreactor with large porous surface for bubble-free oxygen transport has been built up. The biocatalyst packing is distributed between the stages;

• Continuous production experiments have been carried out in the reactor at SATO Ltd. The final glucose content of egg white liquor was in accordance with the expectations.