In Situ Estimation of the Constituents of Green Soybean (Edamame) Pod using Near-Infrared Transmission Spectroscopy

Abstract

Purpose:We estimated the dietary qualities of green soybean (edamame) by using a specialized NIR transmission spectrometer to determine the constitutive properties of the soybean, such as the sucrose content and ninhydrine reaction quantity (NRQ; defined by the ninhydrine reaction, which has a high positive correlation with the total free amino acids), with the purpose of establishing a quality assurance system. Methods: We used a newly developed spectrometer probe that enables in situ estimation of the constituents of the soybean. Results: The calibration results obtained using a wavelength range of 760-960 nm were characterized by R 2 = 0.57 and standard error of cross-validation (SECV) of 0.78% for sucrose, and R 2 = 0.59 and SECV = 0.35% for NRQ. Conclusions: These results are inferior to those of our previous study obtained using a specialized bench-type transmission spectrometer. The poorer results are attributed to several possible reasons, including the effect of direct sunlight and the unstable sample presentation. We plan to conduct further study using improved optical layout and sample presentation.