Submitted to: IFAC/CIGR Workshop
Publication Type: Proceedings
Publication Acceptance Date: 3/10/2006
Publication Date: 12/7/2006
Citation: Kavdir, I., Lu, R., Ariana, D., Ngouajio, M. 2006. Nondestructive quality assessment of pickling cucumbers using visible and near infrared spectroscopy. Borimer Agrartechnische Berichte. 55:97-108. Interpretive Summary: Firmness, skin and flesh color, and dry matter content are important quality parameters for pickling cucumbers and pickled products. Large quality variations often exist in the pickling cucumbers received at the processing plant as they usually come from different growing, storage or handling backgrounds. Rapid, effective quality evaluation of pickling cucumbers before processing would be valuable for controlling and assuring the quality and consistency of final products. Visible and near-infrared (Vis/NIR) spectroscopy, which measures light reflectance or absorption from the sample at wavelengths in both the visible and near-infrared (adjacent to and longer than the visible) spectrum, has good potential for assessing the high moisture crops as it is accurate, fast, economical and, most importantly, nondestructive. This research studied the potential of Vis/NIR spectroscopy for rapid assessment of fruit firmness, skin and flesh color, and dry matter content of pickling cucumbers during the two and one half weeks of cold storage. Vis/NIR spectra were collected from two cultivars of pickling cucumbers, followed by standard destructive measurements of firmness, skin and flesh color and dry matter content. Vis/NIR spectroscopy correlated well with destructive firmness measurements. Vis/NIR measurements had good correlation with skin color. Poor correlation was found between Vis/NIR measurements and dry matter content. This research demonstrated that Vis/NIR spectroscopy is potentially useful for rapid assessment of the quality of the pickling cucumbers. A nondestructive sensing technique based Vis/NIR spectroscopy could be developed for rapid grading and sorting of pickling cucumbers. This would help the pickle industry in providing better quality and more consistent products to the consumer.
Technical Abstract: This study was aimed at developing a nondestructive method for measuring the firmness, skin and flesh color, and dry matter content of pickling cucumbers by means of visible and near-infrared spectroscopy. Two cucumber varieties were tested in the study. Spectroscopic measurements were made from each intact cucumber in the interacting mode over the wavelengths 550-1100 nm. Standard methods were used to measure skin and flesh color, firmness, and dry matter content of the pickling cucumbers. Calibration models were developed using the partial least squares method on relating spectral measurements to individual quality parameters of the cucumbers. Good correlations were obtained in predicting firmness values measured by the slope of the Magness-Taylor force/deformation curve for the pooled data with the coefficient of determination (R**2) of 0.75 for calibration and 0.67 for validation. Better correlations were obtained in predicting skin chroma values (R**2 = 0.89 for calibration and 0.83 for validation). Results for predicting dry matter content of the cucumbers were not satisfactory partly due to the narrow dry matter content distribution among the samples.