Quality assessment of tomato quality by optical absorption and scattering properties

Authors: HUANG, YUPING - Nanjing Agricultural University; HU, DONG - Zhejiang University; Lu, Renfu; CHEN, KUNJIE - Nanjing Agricultural University

Submitted to: Postharvest Biology and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/26/2018
Publication Date: 4/26/2018
Citation: Huang, Y., Hu, D., Lu, R., Chen, K. 2018. Quality assessment of tomato quality by optical absorption and scattering properties. Postharvest Biology and Technology. 143:78-85.

Interpretive Summary: Firmness, soluble solids content (SSC) and pH are three important quality parameters for tomato fruit. Current standard methods for measuring these quality parameters include the puncture and compression test, the refractometer, and the pH meter, which are largely destructive and/or also slow in measurement. In this research, a newly developed spatially-resolved hyperspectral imaging probe was used to measure the optical absorption and scattering properties of 600 tomatoes of different maturity stages over the spectral region of 550-1,300 nm. Mathematical models for predicting these quality parameters were developed using the optical absorption and scattering property data as well as their combined data. Results showed that both absorption and scattering properties were useful for predicting the quality parameters, although the former was consistently better than the latter. Combinations of the two optical property parameters overall improved predictions of firmness, SSC and pH. Good predictions of firmness parameters were obtained with the correlation coefficients of 0.853-0.923, while relatively poor predictions for SSC and pH were obtained. This research showed that optical absorption and scattering properties are useful for nondestructive measurement of quality attributes of tomato fruit, and the spatially-resolved reflectance technique provides a new means for assessing quality of horticultural and food products.

Technical Abstract: This paper reports on the measurement of optical absorption and reduced scattering properties of tomato fruit over the wavelength range of 550 – 1,300 nm, using a newly developed spatially-resolved multichannel optical probe, for assessing the firmness, soluble solids content (SSC) and pH. Tomato firmness, SSC and pH were measured using standard reference methods. Partial least squares models were developed for predicting the three quality attributes. Better prediction results were obtained when using the absorption coefficient and the combinations of absorption and reduced scattering coefficients, especially multiplication of the two parameters wavelength by wavelength. Good predictions of multiple firmness parameters were obtained with the correlation coefficients of 0.835-0.923, while SSC and pH predictions were relatively poor. This research showed that optical absorption and scattering properties are useful for nondestructive measurement of quality attributes of tomato fruit, and the spatially-resolved reflectance technique provides a new means for assessing quality of horticultural and food products.