Diet apples for diet freaks
Date: 13.3.2006
US researchers have developed a transgenic apple tree which bears fruits sweetened with sorbitol.
US researchers have developed a technique which reduces the calories in an apple by about one half. With the help of genetic engineering, they changed the metabolism of apple trees, so they would store sorbitol instead of fructose in the fruit.
As opposed to the fructose, sorbitol has about 45 percent less calories, reports the journal Chemistry & Industry.
Dr. Abhaya Dandekar and his colleagues, from the University of Californa in Davis, first observed these complex metabolic processes in apple trees, which are responsible for the taste, appearance and other properties appreciated by consumers.
Dr. Dandekar’s team discovered that through genetic engineering the content of the natural sweetener sorbitol can be varied in apples. As a consequence, the calorie content of an apple can also be varied.
Normally, sorbitol is produced in the leaves of the tree and it becomes transformed into fructose only inside the apple.
By blocking this transformation, sorbitol remains in the apple and is not converted into fructose.
One gram of sorbitol, according to Chemistry & Industry, corresponds to 2,6 kilocalories, while one gram of fructose corresponds to 4 kilocalories. Thus an “apple light” has 45 percent less calories, when all of the fructose is replaced by sorbitol.
The use of synthetically produced sorbitol as a sugar-replacement is already quite common in the food industry.
Among other things Dr. Dandekar found out that more sorbitol is produced in the apples when sorbitol production in the leaves is suppressed.
Even though these results have been produced using genetic engineering, it would be possible to achieve the same results using classical cultivation, report the researchers.
Also the same technique could replace fructose with sorbitol in other types of fruit, as for example in pears, peaches, plums and cherries. However, it would only have moderate advantages, comments Lynsey Sizer of Weight Watchers in the United Kingdom since fruits and vegetables have generally few calories.
In the food tables of Weight Watchers, one apple corresponds to one point, and thus the genetically modified “apple light” would only count as half a point.
"Source":[ http://www.checkbiotech.org/root/index.cfm?fuseaction=news&doc_id=12287&start=1&control=203&page_start=1&page_nr=101&pg=1].
