Some Visco-Elastic Properties of Mango (Mangifera Indica L.) Fruit
Under Dynamic Conditions
Ben-Hur C. Rafosala1 and Engelbert K. Peralta2
The study was conducted primarily to determine the dynamic rheological properties of mango that would have its concomitant effects as the commodity would be transported from the farm to the market or wherever it might go. A vibrator machine was developed to perform the dynamic testing and transport simulation. Utilizing three ripeness stages, green, breaker, and 30% yellow, and speed ranging from 50 rpm to 200 rpm, the study involved the testing of individual fruit specimens to find the whole mango’s rheological properties using the steady-state sinusoidal dynamic test.
The study corroborated with previous findings that stress varying sinusoidally with respect to time has also its strain varying sinusoidally but in a lag phase. Initial load affects significantly complex modulus but not the phase angle. Yet, both the complex modulus and phase angle rose as frequency increased. Conversely, amplitude and displacement dropped in response to increases in frequency levels as firmness likewise dropped as the ripening process proceeded. It showed a highly significant albeit negative correlation with the phase angle but displayed insignificantly vis-à-vis complex modulus. It displayed no significant effect with respect to frequency. Amplitude decreases as frequency increases; and the vibration force tends to drop as fruit ripens. Firmness is a quality-based fruit characteristic. Complex modulus has a positive relationship with firmness; but phase angle relates negatively with it.
Keywords. Dynamic testing, steady-state sinusoidal dynamic test, complex modulus, phase angle, firmness
Rafosala, B.R. and Peralta, E.K. (2015). Some Visco-Elastic Properties of Mango (Mangifera Indica L.) Fruit under Dynamic Conditions. Philippine Journal of Agricultural and Biosystems Engineering, 11:36-48.