DIELECTRIC PROPERTIES OF FRESH CASSAVA TUBER AT 2-2.90 GHZ MICROWAVE FREQUENCYHEMASANKARI PALANI, S.K. NANDA, K., T. MATHEW, JOE JACOB, V.S. SANTHOSH MITRA AND J.T. SHERIFFUDIN
Rapid quantification of starch present in fresh cassava tuber by electronic means requires a conductivity work at various points of the tuber. The dielectric parameters of different samples of cassava tuber (Manihot esculenta L.) at the S-band of the microwave frequencies were determined. Tubers of cassava varieties of CTCRI, H-226, H-97, Sree Harsha, Sree Prabha, Sree Rekha, Sree Jaya, Sree Sahya, Sree Vijaya, Sree Prakash, Sree Visakham and H-165 were subjected to the cavity perturbation technique. The range of S-band microwave frequency tested were 2247, 2440, 2684 and 2970 MHz. Tubers of the variety H-226 had significantly lower conductivity value was 0.02s/m and the variety H-165, 1.49s/m and are significantly different. The dielectric constant (real part) of tubers of the varieties, H-165 and H-226 were 34.82 and 14.97 respectively and were significantly different. The proximal part of the tuber had the lowest level of conductivity followed by the middle portion and then the distal portion being 0.60s/m, 0.65s/m and 0.69s/ m respectively. The dielectric constant decreases steadily with increase in frequency between 2.00-2.90GHz range for fresh cassava tubers and the dielectric loss factor follows the same pattern. The moisture content of different varieties of fresh cassava tuber, H-226, H-97, Sree Harsha, Sree Prabha, Sree Rekha, Sree Jaya, Sree Sahya, Sree Vijaya, Sree Prakash, Sree Visakham and H-165 ranged between 44.52% and 58.66% as analysed using the moisture analyser at 80 Â°C. The starch content values estimated by the chemical method for all the varieties of fresh tuber ranged between 20.78% and 35.94%. The difference in starch content of tuber between the proximal and the middle region was found to be 3% and that of the middle and distal region was found to be 2%. The conductivity values of fresh cassava tuber can be used for the development of a starch indicator based on moisture content.