Non-destructive moisture measurements of dried fruit samples

A microwave moisture meter has been designed with the specific purpose of measuring moisture in dried fruits. The meter employs absorption techniques, non-destructive and can easily be adapted for on-line measurements. The samples are placed in fixed size containers in 700-900 gr batches. The microwave energy absorption by the samples at certain frequencies is found to be proportional to moisture contents. The previous information about the microwave moisture properties of the dried fruits are stored in a microcontroller. The microcontroller interfaced to the system records the amount of absorption and indicates the moisture levels, after having compared with the stored information and taking the weights, grain sizes and the types of dried fruit samples into account. By this method an accuracy of 2-3% has been achieved. The device is consistent in readings, and is reliable and cost effective.