Non-destructive identification of defects and classification of Hass avocado fruits with the use of a hyperspectral image

D.A. Metlenkin¹*, Y.T. Platov¹, R.A. Platova¹, E.V. Zhirkova¹ and O.T. Teneva²

¹Plekhanov Russian University of Economics, Faculty of Trade Economics and Commodity Science, Department of Commodity Science, Stremyanny lane 36, RU115054 Moscow, Russia
²University of Plovdiv 'Paisii Hilendarski', Faculty of chemistry, Department of Chemical Technology, 24 Tsar Assen Str., BL4000 Plovdiv, Bulgaria
*Correspondence: Metlenkin.DA@rea.ru

Abstract:

Sensory analysis and instrumental analytical methods are used in determining the maturity and quality monitoring of avocado fruits, which are labor-intensive and do not allow the determination of fruit quality in real time. The use of hyperspectral imaging (HSI) methods in the range of 400–1,000 nm and of the multivariate analysis was demonstrated for a non-destructive grading of Hass avocado fruits into quality classes according to the number of hidden defects. Using the sensory analysis, avocado fruits were separated into quality classes according to the number of defects after being stored for 10 days. Development of a classification model included several steps: image recording and analysis using the ANOVA and PCA method, image segmentation (selection of ROI), pre-processing (SNV-correction, centering), selection of a multivariate classification method (PLS-DA, SIMCA) and a spectral range, model verification. The analysis of hyperspectral images of avocado fruits has detected spectral regions with the maximal variance responsible for the change of the content of pigments and moisture within the avocado fruit exocarp. Comparison of PLS-DA and SIMCA models on the basis of best accuracy and test-validation results was carried out. Comparison of models showed SIMCA model as the most efficient model for fruit classification into quality classes depending on the number of hidden defects. The implementation of the developed approach as a digital avocado fruit sorting system at different stages of the product life cycle is proposed.

Key words:

chlorophyll, HSI, Multivariate analysis, PCA, PLS-DA, sensory analysis, SIMCA

Potential of multivariate analyses of X-ray fluorescence spectra for characterisation of the microchemical composition of plant materials

A. Brangule¹³*, M. Bērtiņš², A. Vīksna² and D. Bandere¹

¹Riga Stradins University, Department of Pharmaceutical Chemistry, Dzirciema 16,
LV-1007 Riga, Latvia
²University of Latvia, Faculty of Chemistry, Jelgavas 1, LV-1004 Riga, Latvia
³Baltic Biomaterials Centre of Excellence, Headquarters at Riga Technical University, Kalku street 1, LV-1658 Riga, Latvia
*Correspondence: agnese.brangule@rsu.lv

Abstract:

This work describes a method for the rapid element analysis of plant material using ED-XRF in conjunction with chemometrics. An effective analysis method is developed by measuring certified reference materials (CRM) of plant materials (algae, cabbage, lichen) covering major chemical elements with ED-XRF, to overcome the matrix effect. All samples have been measured additionally by ICP-MS. The ICP-MS analysis was used for missing information on the concentration of some elements in certificated standards. In addition, ICP-MS with CRM has been used to determine sample related element sensitivity for microelements for ED-XRF analyses.

The ED-XRF spectral patterns were used for multivariate principal component analyses by SIMCA strategy instead of each element concentration calculation. The model allows quickly analyse samples for similarity and differentiate them based on a little difference in spectral pattern, which corresponds to a minor difference in element concentration pattern. Samples with specific chemical composition could be easily spotted for in-depth analysis.

The proposed strategy for plant material sample chemical composition screening allows the quick method to improve laboratory work efficiency, reduce unnecessary analysis and rapid method for control reliability of results of more complex chemical methods, such as ICP-MS.

Key words:

chemometrics, ED-XRF, ICP-MS, Multivariate analysis, plants, screening analysis, SIMCA