Changes in Protein Content during Wheat Maturation—What is Measured by near Infrared Spectroscopy?

Abstract

The amount and variation in content of different proteins changes considerably during maturation and these changes were non-destructively monitored in developing grain using near infrared (NIR) spectroscopy. Characteristic changes in two protein absorption bands were identified (2055–2065 nm, identified as amide A/II and 2175–2180 nm, identified as amide I/III) and it was concluded that the different dynamics of protein development (accumulation of proteins as well as gluten network formation) could be followed sensitively by monitoring these two different regions of NIR spectra. Amide A/II represents the effect of protein network formation during maturation based on the vibrations of inter-chain hydrogen bonded N–H groups in polypeptides. Amide I/III is the manifestation of protein accumulation, as in the formation of gliadins and glutenins that interact together to form a gluten network. NIR spectroscopy is shown to be effective in monitoring plant physiological processes both qualitatively and quantitatively, and the spectra have more hidden information for predicting the stage of growth in wheat seed.