Microstructure and creep-recovery characteristics of achu (a taro based paste) made from freeze dried taro chips as affected by moisture content and variety

Achu is a mashed taro paste traditionally obtained by cooking fresh corms until softening, followed by peeling and pounding in a mortar to obtain a smooth and homogeneous paste. In the present study, the utilisation of precooked freeze dried taro chips as convenience food for the preparation of achu was investigated. The Peleg rehydration kinetic model was used to define the conditions for reconstitution. Changes in parenchymous tissue structure and transformation of starch during production of achu from cooked corms and instant chips were followed by light and scanning electron microscopy, stereomicroscopy, and rheology. Four varieties of taro corms and cormels coded WC, RI, MBA and MF were used in this study. The corms were cooked whole, cut into cubes and freeze dried. Unprocessed, processed corms and achu were characterised. As results, the water absorption kinetic of instant chips followed the Peleg model. Reconstituted achu was not significantly different to that made traditionally. The achu paste made from traditional and freeze dried chips consists of starch-filled cells encased in a continuous amylose–amylopectin gel containing some vascular elements and mucilage. This study confirmed that cooking of whole corms/cormels before drying constituted a good approach in the processing of taro flour, usable in the preparation of achu.