Determination of protein and glucose of tuber and root flours using NIR and MIR spectroscopy

Abstract

Infrared spectroscopy associated with chemometrics analysis have been used for protein and glucose determination but researches which compare near-infrared (NIR) and mid-infrared (MIR) spectroscopy especially the ones which study root and tuber crops are rare. In this research, several tuber and root flours, i.e. arrowroot, canna, modified cassava, taro, and sweet potato (purple, yellow, and white) were used. The objective of this study aimed at determining protein and glucose contents of multiple crop flours using a single model for each chemical compound. NIR (10,000–4000 cm−1) and MIR (4000–600 cm−1) spectra as well as chemometrics (principal component analysis, PCA, and partial least-squares regression, PLSR) were used for developing model and analysis. For protein, the best NIR model was developed using original spectra showing Rc2, Rcv2, and Rp2 of 0.97, 0.96, and 0.93, while the best MIR model was developed using SNV method with Rc2, Rcv2, and Rp2 of 0.97, 0.96, and 0.96. Moreover, the best models for glucose were established using MSC pre-processed spectra which have Rc2, Rcv2, and Rp2 of 0.85, 0.78, and 0.86, as well as Rc2, Rcv2, and Rp2 of 0.89, 0.84, and 0.77 for NIR and MIR, respectively. This study showed the potential of NIR and MIR spectroscopy for determining protein and glucose contents of root and tuber flours.