Old bread is being used to create yoghurt, wine and new bread

Old bread is being given a new lease of life as scientists create a ‘secret sauce’ that allows it to be turned into yoghurt, wine and even new bread – all in a bid to tackle food waste

  • The team turn the old and discarded bread into a platform for yeast to grow in 
  • They say this is an alternative to the unused loaves being sent to landfill sites
  • The Italian researchers say it could then be used in commercial bakeries 
  • Their method could be used by bakeries to recycle their own unused produce 

Leftover bread is being given a new lease of life as researchers create a ‘secret sauce’ that lets them turn it into yoghurt, wine and even new bread products. 

The team from University of Bari Aldo Moro in Italy are working to take a bite out of food waste – something they say is a growing problem for the environment.

As much as a third of food produced for human consumption is wasted or lost globally every year, according to lead author Carlo Rizzello.

They plan to take bread that may have been destined for landfill, which generates harmful greenhouse gas emissions, and use it as a medium for growing yeast.

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Researchers hope to take bread that hasn’t been sold by bakeries and supermarkets or used by people at home and turn it into a medium for growing yeast. This stock image shows leftover bread turned into a bowl of croutons for soup or salad

The researchers say the yeast produced using their new old bread medium could be used by the same bakeries that produced the bread being thrown away in the first place to create new bread products – rather than buying yeast from other companies

While exact numbers regarding the amount of bread that is thrown away are hard to estimate, it is believed ‘hundreds of tons are wasted daily worldwide’.

They want to use all that discarded dough to feed the very microorganisms needed in food industries such as bakeries, dairy and wine-making. 

‘We believe that the introduction of innovative bioprocessing technologies might be the key to unravel the burden of food waste,’ Dr Rizzello said.

The team experimented with more than 40 different kinds of growing conditions to find the best combination for various bacteria, yeast and other microorganisms.

The process involved discovering the right recipe of bread amount, enzymes and supplemental ingredients, as well as the ideal time and temperature for incubation.

The goal was to create a wasted bread medium (WBM) that would match or beat current production methods that rely on raw materials.

The scientists formulated a secret sauce using 50 per cent waste bread that was appetising to a wide variety of microorganisms, including yoghurt bacteria.

Crucially, they estimate that the production cost of WBM is about a third that of conventional media.

‘We combine both the need for disposing of the huge amount of bread waste with that of cheap sources for media production, while fitting for the cultivation of several food industry starters, and it is patent pending,’ he said.

The idea is that the WBM protocols could be easily adopted by industrial bakeries, which currently rely on other companies to provide the starters.

The Italian researchers say the aim is to stop more bread from going to landfill sites as they generate harmful greenhouse gas emissions

Those businesses would benefit by ‘using their own waste to produce the medium and propagate the cultures, without modifying [or] adding any equipment to the existing technology,’ said co-lead author Michela Verni.

She added: ‘The strength of our study strictly relies on how easily applicable the protocol is, and proof of its feasibility is indeed the fact that the process is already scaled up at industrial level.

‘Nevertheless, WBM offers a possibility for sustainable starter production to all the food industries working in the field of fermented foods and beverages.’

Dr Rizzello said WBM has applications beyond simple microbial cultivation. 

For example, it could be used as a food ingredient itself with a few tweaks to the WBM recipe and fermentation with different starters.

Or it could serve as a substrate to feed microbes that produce specific compounds used in food supplements or cosmetics.

While WBM appears to be an effective medium for growing lactic acid bacteria and yeasts, Dr Rizzello said further study is needed.

They want to determine if certain components or lack of some micronutrients might affect microbial metabolism in some significant way.

The findings have been published in the journal Frontiers in Microbiology. 


According to the Food and Agriculture Organization of the United Nations, about 2.9 trillion pounds (or a third of the food in the world) is lost or wasted every year.

Fruits, vegetables, roots, and tubers make up the most-wasted foods. 

In industrialized countries, this all amounts to $680 billion in food. In developing countries, it’s $310 billion. 

The average waste per capita in Europe and North America is 95-115 kg, or 209-254 lb, ever year.    

The food lost or wasted in Latin America each year is enough to feed 300 million people. In Europe, it could feed 200 million people, and in Africa, it could feed 300 million people.  

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