Friction index was introduced into the evaluation of food texture. A wedge-shaped probe was inserted into a food sample by a swing arm device for the acoustic measurement of food. Since total weight of the arm, balance weights and probe were known,initial kinetic energy of the inserting probe can be calculated. Displacement and time of the probe after insertion was monitored by a linear encoder. When the probe is stopped within the sample, a food friction index (FFI) was calculated by an equation, 3/4 ×(mv0)/Δl or 3/2 ×(m/Δt), where m is the total weight of the balance, arm and probe, v0 the initial probe velocity at insertion, Δl the probe travelling distance after insertion until the probe stop, and Δt the time from the insertion to the probe stop. FFIs (kg/s) of fresh and stored apple were 40.5 ± 0.8 and 44.1 ± 1.2, suggesting the fresh apple exhibits less FFI and is more crisp. The FFIs obtained by the first and second equation are not significantly different and different insertion velocity of the probe did not affect the results. FFIs of another species of fresh apple, persimmon and banana were 23.6 ± 0.7, 20.5 ± 0.8, and 12.4 ± 0.1, that corresponds to human sensory evaluation.
抄録全体を表示