The effect of grinding time on the texture and physical properties of sesame seeds was studied. Sesame seeds were roasted at 200°C for 10 min in an electric oven and automatically ground in an mortar equipped with a wooden pestle revolving 40 times per minute for 5, 10, 15, 20, 30 and 50 min.
The ground sesame seeds were defatted and separated with six sieves differing in opening (26-850 μm). As the grinding time was prolonged, the weight of finer fractions with a particle size less than 53 μm increased. The amount of oil exuded from the ground seeds was determined by absorbing on paper, reaching 12.3% in the first 5 min of grinding and increasing to 22.9% after continuous grinding for 50 min.
The roasted sesame seeds formed an oily, soft and smooth paste after grinding, and its stickiness increased as the grinding time was increased up to 30 min as judged by a sensory test. However, there was no difference in the total preference.
The changes in scores evaluated by the sensory test for the ground sesame seeds generally corresponded with the change in the amount of exuded oil for the oiliness, MMD measured with a friction tester for the graininess, and texturometer readings for the hardness and degree of adhesiveness.