Large-area coverage–transmission near-infrared measurement of dried laver to determine crude protein content

Abstract

A large-area coverage (LAC)–transmission near-infrared (NIR) measurement scheme was demonstrated to determine the crude protein content of a dried laver sheet. Because dried laver sheets are large (approximately 19 cm × 21 cm) and the algae packing over the sheet is not homogeneous with including numerous void spots, acquisition of sample-representative and reproducible spectra is necessary for reliable quality evaluations. The proposed scheme incorporated a fixed NIR illumination in the y direction and an xz-direction linear motor stage, allowing for a snake scan over an area of 10 cm × 7 cm. This scheme successfully acquired sample-representative and reproducible NIR spectra of nonhomogeneous laver-sheet samples. The predicted crude protein contents of the samples correlated closely with those determined using conventional Kjeldahl analysis, which required destructive sample digestion. The proposed LAC-NIR scheme demonstrated its suitability as a quality assurance tool in real-world field analysis.