Bagher Emadi

Mechanical Properties of Pumpkin

Mechanical properties of three common varieties of pumpkin were evaluated and statistically compared. Toughness, rupture force, shear strength, and cutting force were determined for Jarrahdale, Jap, and Butternut varieties. The investigation was carried out in three cases of flesh, skin and unpeeled product, ignoring the toughness and rupture force of flesh. Relative contribution of skin to unpeeled case of each property was estimated. Varieties were found statistically alike in rupture force, toughness, and maximum shear strength force of unpeeled cases. Also the skin of three varieties showed similar strength in shear (p>0.05). Jap and Butternut varieties for some other properties showed close values. Maximum shear strength force of flesh, shear strength of unpeeled case, and relative contribution of skin to shear strength of unpeeled case were close (p>0.05) for these varieties. Jarrahdale had no difference in shear strength of flesh with two other varieties. It was also similar (p>0.05) to Jap in relative contribution of skin to shear strength, rupture force, and toughness of unpeeled case.

Non-destructive evaluation of maturity and quality parameters of pomegranate fruit by visible/near infrared spectroscopy

ABSTRACT In this study, the potential of visible and near infrared spectroscopy was investigated to classify the maturity stage and to predict the quality attributes of pomegranate variety “Ashraf” such as total soluble solids content, pH, and titratable acidity during four distinct maturity stages between 88 and 143 days after full bloom. Principal component analysis was used to distinguish among different maturities. The prediction models of internal quality attributes of the pomegranate were developed by partial least squares regression. The transmission spectra of pomegranate were obtained in the wavelength range from 400 to 1100 nm. In this research several preprocessing methods were utilized including centering, smoothing (Savitzky–Golay algorithm, median filter), normalization (multiplicative scatter correction and standard normal variate) and differentiation (first derivative and second derivative). It concluded that different preprocessing techniques had effects on the classification performance of the model using the principal component analysis method. In general, standard normal variate and multiplicative scatter correction gave better results than the other pretreatments. The correlation coefficients (r), root mean square error of calibration and ratio performance deviation for the calibration models were calculated: r = 0.93, root mean square error of calibration = 0.22 °Brix and ratio performance deviation = 6.4 °Brix for total soluble solids; r = 0.84, root mean square error of calibration = 0.064 and ratio performance deviation = 4.95 for pH; r = 0.94, root mean square error of calibration = 0.25 and ratio performance deviation = 5.35 for titratable acidity.

Development of a multispectral imaging system for online quality assessment of pomegranate fruit

ABSTRACT The objective of this study was to develop a prototype multispectral imaging system for online quality assessment on pomegranate fruit. At first, a visible/near infrared spectroscopy (400–1100 nm) was tested for non-destructive determination of total soluble solids, titratable acidity, and pH. The spectral data were analyzed using the partial least square analysis. Then to establish consistent multispectral imaging system, the highest absolute values of β-coeffcients correspond to wavelengths from the best partial least square calibration model were selected and used for identifying the optimal wavelengths. Consequently, a multispectral imaging system was developed based on the effective wavelengths 700, 800, 900, and 1000 nm. The performance of the developed multispectral imaging system was evaluated by multiple linear regression models. The multiple linear regression model predict total soluble solids with r = 0.97, root mean square error of calibration = 0.21°Brix, and ratio performance deviation = 6.7 °Brix. Also, the results showed that the models had good predictive ability for pH and titratable acidity. Results showed that the developed multispectral imaging system based on the optimal wavelengths could be used for online quality assessment of pomegranate fruit.

Carob moth, Ectomyelois ceratoniae, detection in pomegranate using visible/near infrared spectroscopy

Abstract In pomegranate, carob moth infestation is a postharvest problem. In most cases, damage develops inside the fruit i.e. without affecting the rind. Consequently, visual inspection is not adequate for identification of carob moth in pomegranate fruit because of the lack of external symptoms. In this study, the feasibility of using VIS/NIR spectroscopy as to detect carob moth infestation in pomegranate fruits is demonstrated. The samples included intact as well as infected pomegranate fruits at four different stages of maturity. Discriminant analysis of the samples was performed by soft independent modeling of class analogy (SIMCA) and partial least squares discriminant analysis (PLS-DA). The results showed that in all sample groups when the samples were classified by PLS-DA, the high values were found in comparison with the SIMCA models. All the discriminate analyses were accomplished for three different sample sets: standard (only the samples handpicked at standard harvest time consist of stage 1, stage 2 and stage 3), last (only the handpicked at last harvest time including stage 3 and stage 4) and combined (all four studied maturity stages together). The total discriminant power of PLS-DA classes was approximately 88%, 90%, and 86% for standard, last and combined sample sets, respectively. The comparison among different sample groups indicated that the last sample group was predicted with the best prediction accuracy followed by standard and then combined sample group.