Microstructure changes of taro (Colocasia esculenta L. Schott) chips and grains during drying

Microstructure changes of taro (Calocasia esculenta L. Schott) chips behaviour during drying at elevated temperature of 50 degrees C, 60 degrees C and 70 degrees C were studied. Scanning electron microscope (SEM) images of taro chips samples taken at the end of each drying step. Series of SEM images shows a fresh section of raw taro chips which honeycomb form cells are clearly observed and distinguishably filled with starch grains. The cells are tightly connected to each other, with approximately has 50-80 mu m size. The compound of starch grain, i.e. amyloplasts, has similar size of approximately 5-15 mu m, yet the cohesion between amyloplast are differs. When subjected to drying temperature of 50 degrees C, corm cells opened. Compound and individual starch grains are clearly visible. By increasing the time, the membrane cells were quietly disappeared, meanwhile the grains shrunk. However, there is no significant size decrease of the grains along the increasing of drying time up to 7 hours. This phenomenon is in line with the moisture content measurement, because since 160 minutes, the low moisture content observed and it's constant for the rest of drying process. As for samples of 60 degrees C, the membrane cells opened further, and the starch grains were mostly appeared in individual granular The grain size is comparable regardless the drying time. By increasing the temperature to 70 degrees C, the impact to grains sizes is quite significant. The polyhedral shape is still observed but is in smaller grains. Therefore, microstructure of taro chips most likely related to their drying behavior at certain subjected drying temperature.