Using brewery waste to grow yeast

Using brewery waste to grow yeast

Spent grain amounts to as much as 85% of a brewery’s waste. Researchers at Nanyang Technological University in Singapore found a way to convert this brewery waste into a valuable feedstock for yeast. We interviewed Professor William Chen, director of NTU’s Food Science and Technology Programme.

What are the current uses of spent grains as a waste product from breweries?

Currently, spent grains are used mainly for animal feeds.


Can you give an estimate of the size of this waste stream worldwide?

In Singapore alone, more than 23,000 tonnes of spent grains are generated every year.


You developed a process to turn the spent grains into a feedstock to grow beer yeast. How does this process work?

It’s a fermentation process, with food grade and non GM microbes, which break down the macromolecules (lipids, proteins and carbohydrates).


How much of the waste stream can be converted using your process?

Our process contains a second part which allows extraction of cellulose from the post-fermented solid waste. As a whole, there is no waste left behind after fermentation and cellulose extraction.


Has the process already been applied on a production scale?

We are in discussion to make our technology at industry level (more than 100 tonnes scale).


What do you consider to be the main advantages for the brewer?

Sustainable and low cost culture medium for the yeast growth. The surplus yeast culture from our technology can be used for other food applications (bakery for example).


Are there other industrial processes where the conversion process can be applied?

Our technology platform has been successfully applied to our side-streams of food processing industry, including soy bean residues.



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Artificial spider silk composite

Artificial spider silk composite

Spider silk is a bioactive material with a wide range of medical uses. Researchers at KTH in Stockholm have synthesized artificial spider silk and combined it with nanocellulose to produce hybrid silk fibers. We interviewed researcher My Hedhammar from KTH.

What process did you use to create the artificial spider silk?

Our artificial spider silk is produced using recombinant DNA technology and a lab bacteria.

What are the advantages of this process compared to the alternatives?

This process is simple, cheap and allows control and scalability.

Does the artificial spider silk have the same properties as natural spider silk?

Our artificial silk contains one miniaturized spider silk protein, which makes it more defined and reproducible than natural spider silk. The initial mechanical properties are essentially the same, with high elasticity and strength. However, the artificial silk is not as extendible as natural silk. Since the artificial silk is made from a defined protein solution, it is possible to process it into a wide variety formats e.g. fibers, films, nets and foam. The recombinant technology also allows functionalization of the artificial silk with bioactive domains such as enzymes, growth factors, affinity modules etc.

Can you tell us something about the properties of the cellulose nano fibrils?

Cellulose nano fibrils can be obtained from trees and are thus renewable and available in large volumes. Moreover, they are biodegradable, virtually non-toxic and offer outstanding mechanical properties.

Which technology was used to combine the spider silk and the cellulose nano fibrils?

We utilized a new method for constructing fibers from nano fibrils, based on flow focusing. Since there are favourable interactions between silk and cellulose, it is possible to include a fraction of silk fusion proteins in the process to obtain composite materials.

What are the main properties of the composite?

The silk-nanocellulose composition gives ultrastrong fibers which have specific bioactivities (from the silk fusions) and are also biodegradable.

Can the properties of the composite be tuned by using a different ratio of silk and cellulose?

By the addition of different silk fusions it is possible to obtain a variety of functional materials with specific bioactivities.

What do you consider to be the possible applications of the composite within healthcare?

For example these composites could be used to develop wound dressings with healing and/or antimicrobial properties, or engineering of load bearing tissue.

Do you also see applications outside healthcare?

Depending on the functionality chosen in the silk fusion, it could be used for e.g. biocatalysts, biosensors or affinity matrices.

Are you licensing the technology for commercial use?

The technology is patented by Spiber Technology AB.

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Low cost E.Coli test

Low cost E.Coli test

E.Coli in drinking water can be a serious health hazard. Researchers at the University of Waterloo have developed a frugal test to test drinking water for E.Coli at a low cost. We interviewed Sushanta Mitra who lead the research and co-founded Glacierclean Technologies, the company that will commercialize the test.

What are the health hazards of E.Coli in drinking water to the individual?

It can cause diarrhea. But more importantly, it is an indicator organism for water quality. If E. coli is present, most likely other pathogens like norovirus etc. are present, which can be very deadly.

Is there a clear view about the causes for E. Coli outbreaks?

Yes, it happens due to faecal contamination by run-off during rainy seasons or cross-contamination between drinking and sewage lines. Also, poor hygiene could be another reason.

How many people are affected by E.Coli worldwide and in which areas particularly?

It can affect billions of people.. 70 % of diseases worldwide are due to water-borne illness. Most vulnerable are the limited resource communities worldwide including those in developing countries.

You developed a paper strip to test for E.Coli. How does the technology to detect E.Coli work?

It is made of paper strip. Paper is a porous material. We apply sugar at the bottom of the paper to attract E. coli (almost fishing bacteria from water). Once E. coli is in contact with paper, due to capillary action both E. coli and water front moves up inside the paper and reach the reaction zone, where we have proprietary chemical reagents that react and produce the colour change.

How accurate is the test?

Currently, we are able to meet the recreational water standards. Work is in progress to meet the US EPA standard for potable water.

You founded Glacierclean Technologies to commercialize the test. When do you expect that the new test becomes available?

It should be available within 9 months. A number of organizations have shown interest in doing field trial with us and we are partnering with them to make our products more robust and field-deployable.

Can you give an indication of the price of the test?

It would be less than 20 cents per test.

What are the other advantages of the new test compared to existing tests?

It is fast, cheap, easy to carry and empowers individuals to have a choice of clean and safe drinking water.

Apart from not drinking the water, what can be done once the E.Coli is detected in the drinking water?

A quick solution is to boil water and also put chlorine tablet. Our rapid detection methods allows individuals to take these measures quickly, thereby avoid falling ill.

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Photo’s: courtesy of Sushanta Mitra