•Accurate NIR calibration models were obtained for main quality indexes of apples.•Total phenolics and antioxidant activity of apples could be predicted by NIR-based models.•Classification models ...were able to discriminate apple lots on the basis of storage time.
Apples can be stored for long time under controlled temperature and atmosphere conditions, and therefore, non-destructive and rapid tools are required to assess fruit quality and to monitor changes during the postharvest period. The aim of this study was to evaluate the feasibility of NIR spectroscopy to optimize postharvest apple management and to follow changes in fruit quality during storage. An FT-NIR system operating in diffuse reflectance in the range 12,500–3600cm−1 was used to evaluate the physico-chemical (dry matter, soluble solids, colour and firmness) and some nutraceutical characteristics (total phenolics, total flavonoids and antioxidant activity) of ‘Golden Delicious’ apples, which were stored for about six months at 1°C in controlled atmosphere, over two subsequent years. Spectral data were elaborated by PLS regression and LDA classification techniques. Good correlation models between spectral data and chemical and physical parameters were obtained for soluble solids, a* colour coordinate and firmness (0.81<R2<0.90 in calibration and 0.79<R2<0.89 in cross validation). Even higher correlation values (0.89<R2<0.95 in calibration and 0.86<R2<0.92 in cross validation) were obtained for indexes correlated to the antioxidant capacity of apples. The classification technique Linear Discriminant Analysis was applied to spectral data, in order to discriminate apples on the basis of storage time. Average correct classification was higher than 93% in validation and close to 100% in calibration, indicating high potential of NIR spectroscopy for the estimation of storage time of apple lots.
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•Non-destructive diagnostic tool was proposed for olive ripening monitoring.•Image analysis, vis/NIR and NIR spectroscopy, and chemometrics were used.•Replacing of traditional ...subjective method in a view of fully automated application.•Comparison of modelling performance of benchtop FT-NIR and portable vis/NIR devices.•Selection of 12 (1.5 nm wide) vis/NIR bands to improve classification models.
A diagnostic visible/near infrared tool calibrated by means of image analysis,was proposed to evaluate the maturation degree of oil olives in order to replace traditional subjective methods in a view of future fully automated applications.
Thirteen varieties of Olea europaea deriving from four regions of the south of Italy were analyzed. In order to objectify the ripening stage assessment, the RGB image was acquired. Spectroscopic analyses were performed using a benchtop FT-NIR and a portable vis/NIR instrument. The benchtop device was equipped with an optical fiber probe and the spectra were collected over the 800–2500 nm range, nominal resolution of 1.6 nm; the portable spectrophotometer cover the range of 400–1000 nm, nominal resolution 0.3 nm. The olive spectral data were modelled using Partial Least Squares - Discriminant Analysis (PLS-DA). The prediction capability reached by the global model (13 varieties were used) obtained from data acquired with both the devices results promising. The PLS-DA models calculated on the olives from Calabria, Sardinia and Abruzzo revealed high prediction capabilities, i.e. sensitivity, specificity and accuracy higher than 83%. The prediction capability of Apulia samples could be improved increasing the variability of the samples since for this region only 3 sampling times were considered. To compare the modelling performance between the benchtop FT-NIR and the portable vis/NIR device, a McNemar’s test was performed resulting no significant difference between the PLS-DA global models. Finally, considering the good performance of the vis/NIR model, a variable selection using the interval PLS (iPLS) algorithm was applied. To reduce the complexity keeping the performance of the model built using the whole vis/NIR spectra (1647 variables), 12 bands (1.5 nm wide) were selected. The new model showed an improvement in terms of model stability and complexity (Sensitivity 86%; Specificity 87%; Accuracy 87%) than the two global models built with the whole vis/NIR and NIR range.
The classification performance provided the groundwork for the development of (i) simplified systems for a direct olives ripening determination on the olive tree, and (ii) automated systems to be applied both in field and at the mill for olives sorting according to the ripening degree.
Background and Aims. The composition of grapes (Vitis vinifera L.) at harvest is a key factor that determines the future quality of wine. The work aimed to evaluate and compare the environmental ...impact of the most evaluated technological parameters using three approaches: the wet-chem method, the optical method using benchtop devices, and the optical method using a prototype smart and cost-effective device (Technology Readiness Level: 5). Methods and Results. The life cycle assessment (LCA) methodology was used to identify the most environmentally sustainable solution in a “from-cradle-to-grave” approach. The functional unit was identified by the execution of the analyses necessary to measure the three technological parameters: TSS, pH, and TA. The findings show that the optical analysis carried out with the prototype is the most suitable and green solution (i.e., with the lowest environmental impact in all the impact categories analysed); in fact, the same technology has proved to be 3.2 times more sustainable than the wet-chem method for the best average environmental performance. Conclusions. The research demonstrated the environmental impact advantages of the optical analyses for assessment of grape composition. Significance of the Study. Innovations in agriculture and the development of smart solutions represent advantages for managing and monitoring the composition of agri-food products that are a green solution for the industry.
The aim of this work is the application of vis/NIR spectroscopy in order to correlate spectral data acquired on intact olives just before or in pastes during the milling process, to the crucial ...parameters for the optimization of the process. Physical measurements (i.e. yield point force and total deformation energy) were performed on the olive samples; after the fruit were crushed for olive paste production, chemical analysis (moisture, oil and sugars content) and maturity index (MI) were measured and correlated to the spectral data. The obtained results were encouraging for chemical, texture and MI parameters, demonstrating the feasibility of real-time prediction of important indices for the milling plant settings. Keywords: chemometrics, milling plant, olive pastes, optical analysis, ripening, texture
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Grape composition at harvest is a key factor determining the quality of future wine. For this reason, measurement of grape characteristics in field during the ripening is a requirement to evaluate ...the right moment for the harvest. Classical chemical analyses, common at the moment in wine industry, have several limits: these take time, are wasteful, destructive, and ultimately inadequate to test fruit in field. Wineries need new practical and quick instruments, non-destructive, and able to quantitatively estimate, in field and on a large scale, the interesting parameters. The goal of the present study was to test an optical portable system for prediction of ripening parameters of fresh berries of grape (Vitis vinifera L. ‘Cabernet Sauvignon’ and ‘Sauvignon Blanc’). In particular, the evaluation of the correlation between vis/NIR spectra and classical destructive ripening parameters was targeted, for samples of both red and white grapes. Each sample was obtained in a different date during the last period of ripening, by averaging the spectral acquisitions of several individual berries. A chemometric regression model was created for each parameter considered. Vis/NIR spectra were correlated with ripening parameters (total soluble solids content TSS, titratable acidity, pH, weight of 200 berries, potential alcoholic degree PAD and sugar/acidity ratio) and with phenolic ripening parameters (extractable anthocyanins EA, total anthocyanins TA and tannins) using the partial least square (PLS) regression algorithm. Principal component analysis (PCA) was performed on spectra too. For both red and white grapes, PCA showed a significant sample grouping for the different acquisition times. PLS models on red grape gave good predictive skills for TSS, acidity and PAD (0.7 < R2 < 0.8, low values of RMSE), and for EA (R2(cv) = 0.74), while less accurate was the model elaborated for TA. Similar results were obtained for white grape (RMSE < 0.9 °Brix for TSS).
Product quality must be maintained at each step of product handling, processing, and preservation, and therefore rapid methods should be available to provide useful information in process management. ...The aim of this review was to give an overview of optical techniques for measuring quality of fruit and vegetables along minimally processed chain. A brief description of spectroscopic and imaging techniques currently used in the fruit and vegetable sector and a selection of applications are presented, paying particular attention to those along pre-, post-harvest and post-packaging phases. Future perspectives about the simplification of these non-destructive techniques were finally explored.
•Overview of rapid techniques to measure fruit and vegetables quality.•Description of optical techniques currently used in the fruit and vegetable sector.•Focus on spectroscopic and imaging applications in the minimally processed chain.•Selection of applications regarding the pre-, post-harvest, post-packaging phases.•Future perspectives about the simplification of optical techniques.
The production of chestnut flour is a viable alternative to their fresh consumption. The principal step of the flour production process is drying, which can be done by different methods. The ...traditional method uses coal as a fuel (low and uncontrolled temperature, long time, low energy consumption), whereas the most widely used method is by convection ovens based on forced warm air (temperature controlled, short drying time, high energy consumption). Therefore, an alternative drying system is desired that is energy efficient and able to preserve product quality. Drying by heat pump decreases processing costs and produces a good quality product with high value added. This research studied the performance of an industrial-sized chestnut drying plant based on a heat pump. The system, equipped with a fan, provides air at a temperature of 25°C to 30°C and at a flow rate of approximately 5 m3/s. A total of 9,430 kg (volume of 12 m3) of fresh chestnuts was processed. During the process, chestnut weight was monitored to obtain the drying curves (from 48%-50% to 7%-11% wet basis). Temperature (T) and relative humidity (RH) levels of the circulating air in the Heat Pump Dryer (HPD) were analyzed to investigate the performances. Throughout, an electric analyzer studied the energy consumption of each component of the plant in order to define all the technical parameters of the drying process. Furthermore, indices to measure the energy efficiency of the drying plant (specific consumption of fresh chestnuts regarding evaporated water, flow of water evaporated, and specific moisture extraction rate) were determined. Finally, two sensorial parameters, color (colorimeter) and odor (electronic nose), were evaluated to characterize the final product resulting from two drying methods: traditional (still locally in use) and HPD.
The aim of this work was to investigate the influence of packaging on measurements of visible-near infrared and near infrared spectroscopy during the shelf life of fresh-cut Valerianella leaves and ...Golden Delicious apple slices. Principal component analysis and partial least square discriminant analysis were applied on spectral data to reach the objectives.
Results on Golden Delicious could be considered satisfactory even if the classification performances were lower than those obtained for Valerianella; however, overall collected positive predictive values ranged from 86.7% to 100.0%. The presence of packaging had only a slight effect on classification capability. These findings would be useful in the development of freshness decay assessment tools using these optical techniques along products' post-packaging chain.
•Vis/NIR and NIR spectroscopy were used to monitor fresh-cut salad and apple.•The aim was to investigate the packaging influence on the optical measurements.•Spectra were acquired in contact with the samples surface and through the packaging.•PLS-DA classification models were built for the two measurement conditions.•The classification performances were considered to evaluate the packaging influence.
