HARDNESS OF COOKED MILLED RICE BY INSTRUMENTAL AND SENSORY METHODS

Fifteen milled rice varieties covering the usual range of amylose cont ent and cooked rice hardness were used in a collaborative study to ver ify the sensitivity of the present objective method for measuring cook ed rice hardness. The grains were cooked either in a rice cooker using a fixed water: rice ratio of 2:1, or by boiling in excess water for t he predetermined optimum cooking time for each sample followed by drai ning. Hardness of cooked rice was measured in an Instron Universal Tes ting Machine (UTM) using two methods: (1) puncture of 100 individual g rains and (2) extrusion through a 30 cm2 Ottawa Texture Measuring Syst em (OTMS) cell with either a 3.2- or 4.8-mm-diam. holes plate. Hardnes s values were compared with sensory scores by a trained panel composed of 11 members. Sensory hardness of the rices cooked in a fixed amount of water showed very good correlation with puncture force (r = 0.94, P < 0.01) and with extrusion force through a 3.2-mm-diam. holes plate (r = 0.94). The correlation coefficient between puncture force and ext rusion force was 0.97. Paired comparison test by the sensory panel on three pairs of rices verified consumers' claims with respect to prefer ence between members of each pair and agreed with results of ranking t est.