Water extraction process can increase safety and decrease costs

Water can replace solvents in food and pharmaceutical processing, reducing costs and eliminating the environmental problems associated with some industrial solvents, according to University of Arkansas researchers Ed Clausen and Julie Carrier.

'It has always amazed me that a chemical as toxic as hexane is used as a solvent in processing soybeans, for example,' said Clausen. 'I think it has largely been a matter of using something you know works rather than trying to find a less-toxic alternative.'

Clausen and Carrier developed their water-based extraction process while studying milk thistle. Carrier, who specialises in neutraceuticals, needed a safe method for extracting the active ingredients, flavonolignans, from the plant.

'Neutraceuticals are plant-based extracts that are effective in treating diseases,' explained Carrier. 'Milk thistle, for example, contains six compounds that may have therapeutic value in treating several diseases, including prostate cancer and liver disease.'

Clausen and Carrier compared their hot-water extraction process with a standard chemical extraction process and found that similar concentrations of the compounds were obtained by using both processes.

'Under certain temperature and pressure conditions, water begins to act like an organic solvent,' explained Clausen. 'Although this is a known phenomenon, it has not been applied to food and pharmaceutical processing before.'

Current industrial processing techniques use a solvent, such as hexane, to extract the desired compounds from the plant. The solvents must then be removed before the compound can be used.

Water extraction is a cost-effective alternative because it eliminates the solvent-recovery stage. In addition, water is less expensive than most industrial solvents.

'Water extraction allows us to reduce the number of steps in the process,' Carrier explained. 'And because it is environmentally benign, it doesn't present many of the problems encountered with use and disposal of many industrial solvents.'