Stale bread crumbs used to make alcohol-based hand sanitiser

Dr Stefan Hayward Picture: African News Agency (ANA)

Dr Stefan Hayward Picture: African News Agency (ANA)

Published Apr 2, 2020

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Cape Town – Stellenbosch University (SU) students have proven that with the right equipment, some ingenuity and a few loaves of bread, you can do almost anything in times of crisis.

The SU food scientists made 18 litres of alcohol-based hand sanitiser from stale bread crumbs in their in-house fermentation tank.

After a week-long process, they were able to bottle the end product hours before South Africa went into lockdown because of Covid-19.

Departmental staff were able to take a good supply of hand sanitiser home. A few bottles were left at the ready in the Food Science building for when authorised staff visited the facility to check up on the running of experiments.

“It smells just a little bit like toast,” said Dr Stefan Hayward, a postdoctoral researcher in the Department of Food Science at SU.

He is part of a research group in the Department who on a normal day focuses on ways to reduce food waste being produced, on the one hand,

and on another, on ways to put these by-products to use.

“Waste implies a need to discard something which has become useless and needs to be disposed of.

"We see waste products and the tendency to produce too much food not as a problem, but as raw ingredients or by-products that can provide the impetus to invent new ways of reducing, reusing and recycling,” he explained.

The plan to make their own hand sanitiser came a day after the Presidency announced self-isolation measures, during a brainstorming session

between Dr Hayward, another postdoctoral researcher, Dr Timo Tait and MSc food science student Sebastian Orth.

“We were talking about alternative uses for some of the everyday items we often discard, bread being one of them,” remembers Dr Hayward.

They decided to try and produce bio-ethanol from bread with which to make hand sanitiser.

“Bread is composed of 40% starch, which can be used as an excellent carbohydrate source during the production of bio-ethanol via fermentation,” Hayward said.

“The global Covid-19 pandemic has highlighted the need for better hygiene practices and adequate supplies of antiseptic products such as hand sanitiser to help ‘flatten the curve’,” he added.

In the Department’s fermentation tank, they combined 60kg of bread crumbs with hot water and added alpha amylase enzymes that are regularly used in the food industry to the mix.

They then adjusted the pH level to optimal levels to convert starch to sugar.

The mixture was then incubated at 65°C for 60 minutes to enable saccharification, and therefore sugar production. Thereafter, the mixture was cooled to 30°C before a specialised yeast strain used by the distilling industry was added.

The end product, which looks very much like mashed potatoes, was left at room temperature for seven days until the fermentation process was complete and they could start distilling the mixture.

From the initial 60kg of bread in their first batch, they were able to produce 10.5 litres of 75% ethanol. Because of the lockdown, the researchers could not continue their work, but they hope to do so once the situation returns to normal in the country.

Cape Times

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