A Simplified, Light Emitting Diode (LED) Based, Modular System to be Used for the Rapid Evaluation of Fruit and Vegetable Quality: Development and Validation on Dye Solutions

Abstract

NIR spectroscopy has proven to be one of the most efficient and ready to transfer tools to monitor product’s quality. Portable VIS/NIR instruments are particularly versatile and suitable for field use to monitor the ripening process or quality parameters. The aim of this work is to develop and evaluate a new simplified optoelectronic system for potential measurements on fruit and vegetables directly in the field. The development, characterization and validation of an operative prototype is discussed. LED technology was chosen for the design, and spectral acquisition at four specific wavelengths (630, 690, 750 and 850 nm) was proposed. Nevertheless, attention was given to the modularity and versatility of the system. Indeed, the possibility to change the light sources module with other wavelengths allows one to adapt the use of the same device for different foreseeable applications and objectives, e.g., ripeness evaluation, detection of particular diseases and disorders, chemical and physical property prediction, shelf life analysis, as well as for different natures of products (berry, leaf or liquid). Validation tests on blue dye water solutions have shown the capability of the system of discriminating low levels of reflectance, with a repeatability characterized by a standard deviation proportional to the measured intensity and in general limited to 2%–4%.

Potential effectiveness of visible and near infrared spectroscopy coupled with wavelength selection for real time grapevine leaf water status measurement

“…A limited number of already built prototypes of simplified systems based on the analysis of a few variables can be found in the literature. Civelli et al . designed and tested a simplified, LED‐based, modular system to be used for the rapid evaluation of fruit and vegetable quality, and preliminary tests performed on a lab scale using dye solutions gave encouraging results.…”

“…Recently, considerable effort has been directed towards developing and evaluating different procedures for the objective identification of variables which contain useful information and the elimination of variables containing mostly noise . This selection reduces the cost of the potential miniaturized devices built only with the selected wavelengths . The selection of these optimal wavelengths reduces the size of the required measurement data while preserving the most important information contained in the data .…”

Monitoring strategies for quality control of agricultural products using visible and near-infrared spectroscopy: A review

“…The main differences between these types of NIR devices and an overview of spectroscopy applications on fruits and vegetables based on the instrumental characteristics of the NIR devices employed for the studies can be found in Beghi et al (2017). The literature shows that many applications of VIS-NIR spectroscopy involve the use of benchtop and portable full spectra devices, but recent studies have been conducted using simplified optical systems based on a small number of wavelengths (Beghi et al, 2013;Giovenzana et al, 2014;Civelli et al, 2015). This topic is discussed in Beghi et al (2017).…”

Detection of contaminants in water supply: A review on state-of-the-art monitoring technologies and their applications

“…A novel and simplified optoelectronic system was designed on the basis of an NIR technique at wavelength acquisitions of 630, 690, 750 and 850 nm using a LED as a light source for evaluating fruits and vegetables [339]. Validation was performed on dye solutions resulting in the system's ability to discriminate among the reflectance rate's low limit levels, which were in the range of 2-4%.…”