Identifying Rotten Potatoes

Description and Advantages

Physicists in England have developed a sensor to identify rotten potatoes while in storage and this could save an estimated 5.7 million pounds. The sensor, developed by physicists at the University of the West of England, is used to detect organic compound in the air space around the potato tubers indicating an infection in the vegetables.

Bacterial soft rot, caused mainly by the bacterium Erwinia carotovora is a major problem in the bulk storage of many vegetable crops.

Under favourable conditions the bacteria can change infected potato into wet, rotten tissue which quickly infects surroundings tubers and spreads the infection rapidly.

Bacterial infection of this type is accompanied by an increase in the concentration of odorous organic compounds in the air space above the tubers and it is these gases that the sensor sniffs out to detect the rot.

A number of heated ceramic sensors were tested at an operating temperature of 350 degree celsius by the researchers. In normal air, sensors have an electrical resistance that depends on the concentration of oxygen present. When the oxygen reacts with the volatile organic compounds produced by the potato tubers, this causes a change in the oxygen concentration and thus a change in the resistance of the sensor.

The larger the change, the more obvious gases being produced by the vegetables.  The sensors - based on ceramic materials - showed a high sensitivity to the organic vapours and an added bonus is that they are also relatively inexpensive.

Using their experimental results the researchers used the best performing sensors to make a prototype detector tuber in 100 kilograms (approximatley 900 potatoes).

Source: Chemical Weekly, 24 APRIL, 2001