Quick Dips

Sweet Success

The search for a means of economically producing a food additive may mean sweeter strawberries in future, if research at the University of Canterbury pays off.

Canterbury's Biotechnology Research Group has been able to insert genetic material coding for a protein sweetener into a variety of plants, resulting in sweeter produce. The protein, thaumatin, is usually extracted from an African plant and has been used for centuries to sweeten food. Dr David Leung says the project aimed to produce quantities of thaumatin in plants that could be grown easily outside Africa.

Overseas teams tried inserting the protein's gene sequence into microorganisms, using the traditional recombinant DNA approach. Leung's postgraduate students thought that the plant protein sequence might be better expressed if inserted in plants. Potatoes and rock melons used in the first trials have all been sweeter as a result.

"The initial project was to test the hypothesis, " says Leung. "With the strawberries, the goal would be more ambitious." Leung points out that, unlike many horticultural projects, his group aims to improve the quality of the produce, rather than to improve yields.

It will be some time before genetically-sweetened strawberries will be on the market, but other groups in New Zealand and elsewhere are keen to use the technique on a range of produce.