新技术可使面包保质60天

 

An American company has developed a technique that it says can make bread stay mould（模具，霉）-free for 60 days.

 

The bread is zapped in a sophisticated microwave array which kills the spores¹ that cause the problem.

 

The company claims it could significantly reduce the amount of wasted bread - in the UK alone, almost a third of loaves purchased.

 

The technique can also be used with a wide range of foods including fresh turkey and many fruits and vegetables.

 

Food waste is a massive problem in most developed countries. In the US, figures released this year suggest that the average American family throws away 40% of the food they purchase - which adds up to $165bn annually².

 

Bread is a major culprit（犯人，罪犯）, with 32% of loaves purchased in the UK thrown out as waste when they could be eaten, according to figures from the Department for Environment, Food and Rural Affairs (Defra).

 

One of the biggest threats to bread is mould. As loaves are usually wrapped in plastic, any water in the bread that evaporates（蒸发，消失） from within is trapped and makes the surface moist. This provides excellent growing conditions for Rhizopus stolonifer, the fungus³ that leads to mould.

 

In normal conditions, bread will go mouldy in around 10 days.

 

But an American company called Microzap says it has developed a technique that will keep the bread mould free for two months.

 

At its laboratory on the campus of Texas Tech University in Lubbock, chief executive Don Stull showed off the long, metallic⁴ microwave device that resembles an industrial production line. Originally designed to kill bacteria such as MRSA and salmonella, the researchers discovered it could kill the mould spores in bread in around 10 seconds.

 

"We treated a slice of bread in the device, we then checked the mould that was in that bread over time against a control, " he explained.

 

"And at 60 days it had the same mould content as it had when it came out of the oven."

 

The machine the team has built uses much the same technology as found in commercial microwaves - but with some important differences, according to Mr Stull.

 

"We introduce the microwave frequencies in different ways, through a slotted radiator⁵. We get a basically homogeneous signal density⁶ in our chamber⁷ - in other words, we don't get the hot and cold spots you get in your home microwave."

 

The company's device has attracted plenty of interest from bread manufacturers - but it is worried that it could push up costs in an industry where margins⁸ are very tight.

 

And there is also a concern that consumers might not take to bread that lasts for so long. Mr Stull acknowledges it might be difficult to convince some people of the benefits.

 

"We'll have to get some consumer acceptance of that," he said. "Most people do it by feel and if you still have that quality feel they probably will accept it. "

 

Mr Stull believes that the technology could impact bread in other ways. He said that bread manufacturers added lots of preservatives⁹ to try and fight mould, but then must add extra chemicals to mask the taste of the preservatives. If bakers¹⁰ were able to use the microwave technology, they would be able to avoid these additives¹¹.

 

While a wholesale¹² change in the bread industry might be difficult to achieve, there may be more potential with other foods, including ground turkey.

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