جستجوی مقالات مرتبط با کلیدواژه « Firmness » در نشریات گروه « مکانیزاسیون کشاورزی »

Quality assay and caring of fruit and vegetables has basic role on modern agricultures today. Photoacoustics is a new method of non-destructive detection of the properties of biological materials, in which light energy is used to produce ultrasonic waves in various materials.The received ultrasound waveform contains useful information about the textural properties of the adsorbent medium. This research investigated and evaluated the quality of three peach cultivars during their storage period using non-destructive photoacoustic method in comparison with destructive penetration method. For this purpose, a system for ultrasound wave generation was implemented using laser pulse radiation with a wavelength of 1064 nm. The maximum amplitude of the photoacoustic signal and the time of occurrence of this amplitude were extracted from the experimental samples. Also, by separate penetration test, the amount of firmness and modulus of elasticity were measured on the same samples. By selecting the factors of peach cultivar, size and caring time, the obtained data were analyzed in a completely randomized experimental design with 5 replications. Finally, the means of the two sets of data obtained from the two tests were compared by examining the correlation coefficients. The results showed that in all sources of variables in the measurement indices except the size factor in the maximum signal index there is a significant difference between the averages of the indices at the level of 5%. Over time, the maximum signal amplitude index decreased. As the sample size increases, the maximum amplitude time value increases more. There was a significant difference between the two levels of care. There was an interaction between factor of peach cultivar and factor of caring time. The results showed that the modulus of elasticity decreased in larger sizes. Comparison of the means of peach cultivar factor in firmness index showed that there is a significant difference in all three levels. The highest amount was in Balkhi cultivar and the lowest amount was in Zafarani cultivar. The mechanism of the photoacoustic signal produced by laser radiation on the surface of the material depends on the mechanical properties of the irradiated material and the properties of the light source. Therefore, the change in signal amplitude is affected by the initial pressure wave caused by the laser radiation on the surface of texture. Based on the results, the time of occurrence of the maximum signal is a good indicator to assess the quality of peach fruit texture during its care period. The results of correlation between the data of the two tests showed that the highest correlation coefficient between texture of firmness and the maximum amplitude of the photoacoustic signal is for three cultivars. So that Balkhi cultivar had the highest correlation coefficient equal to 0.821. These results prove the validity of non-destructive and non-contact measurement methods in texture quality.

A robust numerical analysis was proposed for simulating the rebound velocity pendulum method for melon. For considered varieties (Zard-Eyvanekey and Sousky-Sabz varieties), the change in impact parameters (extracted from excitation by pendulum) was studied for five stages of ripening. With the melon ripeness, the rebound velocity, rebound height, relative rebound height, rebound angle, rebound energy and coefficient of restitution (velocity ratio) increased, while the absorbed energy decreased (from 37.6 to 27.9 MJ for Zard-Eyvanekey and from 38.5 to 27.9 MJ for Sousky-Sabz). The regression analysis showed a highly significant linear relationship (coefficient of determination, R² more than 0.8059) between impact parameters and five stages of ripening. So the results of the analysis are feasible in ripening detection and hence in the classification of the melon maturity.

Development of ultrasound technique has not been progressing for evaluating the internal quality of fruits as fast as that of processed foods. In this research for quality assessment of pear fruit (Shah Miveh variety) an ultrasonic measurement system was constructed to transmit and receive the ultrasonic waves. The apparatus included a pulser-receiver، a pair of 75 kHz ultrasonic transducers with exponential horn، and a computer system for data acquisition and analysis. Several mechanical and chemical properties، including firmness، TSS، acidity، elastic modulus، pH and total dry matter for destructive quality assessment were measured. Velocity and attenuation of ultrasonic waves for nondestructive tests were also measured. The fruit quality levels for the experiment were: unripe، ripe and overripe. The results of tests showed that firmness was the best parameter for measuring fruit quality، as it decreased significantly with ripeness. The effect of ripeness on the velocity and attenuation of ultrasonic waves was also significant. Investigation showed a positive linear relationship between fruit firmness and wave velocity (R2=0. 81). Furthermore، the relationship between fruit firmness and attenuation was exponential and wave attenuation decreased with increasing fruit firmness (R2=0. 895). The Relationship between ultrasonic properties and fruit modulus of elasticity showed that the wave velocity increased and attenuation decreased with increasing elasticity. It can be concluded that the ultrasonic instrument equipped with exponential horns can effectively be utilized for pear quality assessment based on measurement of wave velocity and attenuation.

In this research، kiwifruits (Hayward) were selected in two mass ranges (large and small). They were placed in one-liter glass bottles in the vicinity of the polyethylene sachets containing potassium permanganate nano-zeolite (0، 0. 2، 0. 4 and 0. 8 g) and were stored in a germinator (5°C temperature and 30% relative humidity). Then، the physicochemical properties of the fruits (soluble solid content، pH، moisture content and fruit firmness) and potassium permanganate nano-zeolite color (L، Hue angle، Chroma and E) were measured after t 0، 2، 4 and 6 weeks of storage. The factorial treatment structure based on completely randomized block design was used for analyzing the obtained data. The results of analysis showed that potassium permanganate nano-zeolite had a significant effect on the measured physicochemical properties، except for the moisture content (P)