July 28/MINT -- Biochemists at the Indian Institute of Science (IISc) say they have separated a novel enzyme from rice bran that is capable of converting cooking oils containing triacylglycerol (TAG) into a much healthier diacylglycerol (DAG).

The fatty acid constituent TAG in cooking oils is considered unhealthy, as high levels of it in the bloodstream can lead to increased risk of heart disease and stroke. DAG oil, on the other hand, has numerous health benefits, including reducing post-meal blood TAG levels and increasing the overall metabolism, thus helping reduce fat already stored in the body.

"We have identified and purified a DAG generating enzyme (lipase) from rice bran that cleaves one of the three fatty acids from TAG, converting it into DAG," says Ram Rajasekharan, a professor of biochemistry at IISc.

The department of biotechnology (DBT) is funding one of Rajasekharan's researches in this area, called "metabolic engineering to produce TAG-anti-obesity oil", where he has recorded initial success.

Tokyo-based health and chemicals company Kao Corp. holds a patent for DAG oil and started commercially producing DAG oil in Japan using "general" enzymes from Denmark-based Novozymes AS. Kao markets DAG oil in the U.S. in a 50/50 venture with Decatur, Ill.,-based cereal and seed company Archer Daniels Midland Co.

"Now, we have found a new process to produce this oil, and although we cannot call it DAG oil, the end product is the same," Rajasekharan says.

The IISc research group is looking at many things, but there are two relevant aspects to DAG as an anti-obesity oil, says G. Padmanaban, head of the DBT committee and professor emeritus at IISc.

"He (Rajasekharan) could put this gene in a suitable microorganism and produce DAG as a product, and put the gene in oil seed and express the gene so that the oil will be rich in DAG," says Padmanaban.

Rajasekharan has isolated a mutant yeast that is capable of accumulating "13-16% of its dry weight as DAG with no TAG," he says.

"We are now genetically engineering yeast so that it can accumulate 40-50% of its dry weight as healthy oil, which is good enough for commercial production," he adds. This yeast can then be used in a regular fermentation process to produce oil rich in DAG.

Rajasekharan says if his research works, it could provide an economical alternative method for DAG.

"It's a very promising area of work and needs to be explored further with the industry," says P.P. Srivastava, a professor of agricultural and food engineering at the Indian Institute of Technology, Kharagpur, who has earlier used enzymes to increase extraction rates of rice bran oil.

Rajasekharan, who has licensed some of his innovations to Dow Chemical Co. and ITC Ltd., says the industry should come forward to scale up lab technologies for the market. "Another possible use of this enzyme is that it can be engineered as a supplement to convert the conventional 'obese' oil into 'slim' oil in the body," he says.  

From the August 4, 2008, Prepared Foods e-Flash