Master's thesis - Developing microscopy methods for evaluation of bioprocessing of Brewers’ spent grain

Publiceringsdatum: 2018-07-25


RISE is Sweden’s research institute and innovation partner. Through our international collaboration programmes with industry, academia and the public sector, we ensure the competitiveness of the Swedish business community on an international level and contribute to a sustainable society. Our 2,300 employees engage in and support all types of innovation processes. RISE is an independent, State-owned research institute, which offers unique expertise and over 100 testbeds and demonstration environments for future-proof technologies, products and services.


Brewers´ spent grain (BSG), the insoluble residue that is separated from the mash before fermentation, is the most abundant beer brewing by-product. Average annual global production is estimated to be ~39 million tons, of which 3.4 million tons produced in the European Union. BSG is mainly constituted by
fibers (more than 50% w/w) and protein (up to 30% w/w), which make this material very attractive for subsequent use in food industry. Despite its potential, at present, the majority of BSG is used as low value animal feed or it is discarded. One of the reasons for the poor exploitation of BSG is its poor technological performance as food ingredient. Currently, no recycling solution exists on a large scale and sustainable approach for BSG valorization should be implemented.

Bioprocessing has shown great potential for the enhancement of many food by-products. Tailored bioprocessing with selected microbial strains (e.g. lactic acid bacteria) in combination with hydrolytic enzymes, will enable the production of functional compounds in BSG, improving its overall quality and usability as food ingredient. During bioprocessing, BSG is transformed, resulting in improved structure, as well as enhanced bioactivity and bioavailability of BSG constituents. The aim of FUNBREW is to establish bioprocessing technologies for the synthesis in situ of functional compounds in BSG, such as exopolysaccharides (EPS) and antioxidants. The project goal is to obtain fundamental understanding on the biochemical and structural modifications occurring during BSG biotransformation to establish its use as food ingredient.

Description of work
In the first part of this master thesis work the microstructure of BSG will be characterized before and after different pre-treatments. Several staining techniques and microscopy methods will be addressed and optimized. The morphology of BSG will be studied using light microscopy (LM) after staining of
cell walls, starch, and protein. In particular, arabinoxylan (AX) and β-glucan, will be visualized with confocal laser scanning microscopy (CLSM) using immuno-labelling with specific antibodies.

The second part is to develop a staining method for EPS, where the EPS can be distinguished and localized in the sample. Fluorescently labelled lectins will be used to stain the EPS and the analysis will be performed by CLSM. Lectins are widely used for staining of biofilms. The first screening of different stains will be performed on bacteria growing as a biofilm. The stains showing the best result will be further tested on BSG to assess the possibility to distinguish EPS in the complex matrix.

As a candidate for this MSc project you should preferably like experimental work, be independent and creative. A suitable background is food chemistry and biochemistry. The work is planned for the autumn 2018. It’s possible to extend the project to one year, a third part will then be added.

The work will be carried out at RISE Research Institutes of Sweden, Agrifood and Bioscience, Frans Perssons väg 6, Gothenburg.

Application deadline is August 22nd, but due to the early start of the thesis we look forward to you application as soon as possible. The position may be filled before the application deadline.  

For more information, please contact:
Annika Krona, 010-5166638.


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