Rheology and microstructure of achu, a food based on taro (Colocasia esculenta L. Schott), as affected by method of preparation

The functional properties of flour and the organoleptic, rheological and microscopic characteristics of traditionally made achu were compared with those of reconstituted achu prepared from the taro variety Ibo coco. Organoleptic analyses showed that reconstituted achu was generally softer in consistency and less appreciated than traditional achu. In general with respect to functional properties, the estimated water absorption capacity, bulk density, blue value index and penetrometric index were lower for traditional achu than for reconstituted achu. In contrast, the viscosity of traditional achu was significantly higher than that of reconstituted achu. Light microscopic observations revealed that reconstituted taro achu is a smooth starch gel containing broken parenchyma cells whereas in traditional achu, the paste is mainly composed of whole cells within a starch gel. Coulter particle size analyses of achu showed a peak at median 122 μm for traditional achu whereas reconstituted-flour achu had its median at 143 μm. All the functional, rheological and microscopic analyses reflect the higher degree of starch gelatinisation in the reconstituted achu. From this study, it is suggested that boiling the whole corms before drying could improve the texture of the reconstituted achu. © 2006 Society of Chemical Industry.