June 29, 2007 You can say goodbye to the unpopular brown potato chip, thanks to a University of Guelph scientist who has found an enzyme that ensures potatoes stay golden when cooked.
Food scientist Rickey Yada has discovered an enzyme in a particular potato variety that prevents chips made from cold-stored Ontario potatoes from browning.
“Not very many people like brown chips because they don’t look as appetizing and they taste bitter,” said Yada, who worked with a team of researchers in Guelph’s departments of Food Science and Plant Agriculture. “We’ve basically found an enzyme that prevents the chemical reaction that leads to browning.”
The cold temperatures needed for long-term storage of potatoes cause the starch in spuds to break down into smaller sugar molecules. It’s the reaction between these sugars and the extreme heat of deep frying that causes browning.
“The longer you refrigerate potatoes, the more starch converts to sugar to cause the browning,” Yada said.
Yada has found an enzyme in a certain variety that allows the potato to be stored at colder temperatures without turning brown.
The enzyme he and his team discovered helps convert the broken-down sugars into other molecules, reducing the browning effect. Called pyruvate decarboxylase, the enzyme was found in a potato from North Dakota.
Yada said introducing the gene for the enzyme into local potato varieties will enable producers to store them at a lower temperature, allowing for a year-round supply for chip production without the high percentage of browning. This would be a big plus not only for the avid chip eater but also for the $26.8-million chip industry in Ontario. Currently, about 10 to 15 per cent of the potatoes stored for chip production turn brown, according to the Ontario Potato Board.
“Since Ontario chip manufacturers suffer from having just a single harvest season, we can’t keep enough domestic supply and end up importing potatoes from other provinces and the United States,” said Yada.
“But if we are able to store potatoes at a lower temperature, then we can store them longer and replace the imported portion with a local supply.”He and a team of researchers are currently working towards introducing the gene for the enzyme into Ontario potato varieties.
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