Development of a multichannel hyperspectral imaging probe for property and quality assessment of horticultural products

Authors: HUANG, YUPING - Nanjing Agricultural University; Lu, Renfu; CHEN, KUNJLE - Nanjing Agricultural University

Submitted to: Postharvest Biology and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/10/2017
Publication Date: 7/26/2017
Citation: Huang, Y., Lu, R., Chen, K. 2017. Development of a multichannel hyperspectral imaging probe for property and quality assessment of horticultural products. Postharvest Biology and Technology. 133:88-97.

Interpretive Summary: Improved techniques for nondestructive quality assessment of food products are needed in order to meet the increasing consumer demand for food quality, reduce food loss, and ensure profitability for producers and retailers. In recent years, visible and near-infrared technique has been widely used for nondestructive measurement of properties and compositions of agricultural and food products. However, the technique only provides point measurements and cannot be used for measuring the spatially varying properties and condition of food products. While hyperspectral imaging technique has emerged in recent years as a powerful tool for obtaining both spatial and spectral information of food products, it often has limited spectral regions and lacks flexibility in dealing with food products of varying geometry. In this research, a new multipurpose, multichannel hyperspectral imaging probe was developed for nondestructive measurement of optical properties and quality of food products. The new multichannel detection probe enables to obtain 30 spatially resolved spectra simultaneously over the spectral region of 650-1,650 nm from food samples with flat or curved/irregular surface. These spatially resolved spectra can be used for determining the optical absorption and scattering properties, which are related to the structural and chemical properties of food, as well as for directly assessing the condition and characteristics of food products at varying depths. Calibration procedures for the detection probe were developed and carried out. The detection probe was used to measuring the optical properties of liquid model samples, which compared well with the two reference measurement methods. Furthermore, it was used to measure the optical absorption and scattering properties of tomatoes of different maturity levels. The new detection probe provides enhanced capabilities for optical property measurement and quality assessment of horticultural and food products.

Technical Abstract: This paper reports on the development, calibration and evaluation of a new multipurpose, multichannel hyperspectral imaging probe for property and quality assessment of food products. The new multichannel probe consists of a 910-miscrometer fiber as a point light source and 30 light receiving fibers of three sizes (i.e., 50 micrometers, 105 micrometers and 200 micrometers) arranged in a special pattern to enhance signal acquisitions over the spatial distances of up to 36 mm. The multichannel probe allows simultaneous acquisition of 30 spatially-resolved reflectance spectra of food samples with either flat or curved surface over the spectral region of 550-1,650 nm. The measured reflectance spectra can be used for estimating the optical scattering and absorption properties of food samples, as well as for assessing the tissues of the samples at different depths. Several calibration procedures that are unique to this probe were carried out; they included linearity calibrations for each channel of the hyperspectral imaging system to ensure consistent linear responses of individual channels, and spectral response calibrations of individual channels for each fiber size group and between the three groups of different size fibers. Finally, applications of this new multichannel probe were demonstrated through the optical property measurement of liquid model samples and tomatoes of different maturity levels. The multichannel probe offers new capabilities for optical property measurement and quality detection of food and agricultural products.