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

Abstract

The role of bread, pasta and related products produced from milled wheat seeds is important to the human diet, so monitoring changes of starch content in developing grain is essential. Immature wheat grains are also used as a functional food, particularly as a source of water-soluble carbohydrates. The amount and variation in content of different carbohydrates changes considerably during maturation and these changes were non-destructively monitored in developing grain using near infrared (NIR) spectroscopy. Characteristic changes in three carbohydrate absorption bands [1585-1595 nm (Carbohydrate I), 2270-2280 nm (Carbohydrate II) and 2325-2335 nm (Carbohydrate III)] were identified and it was concluded that the different dynamics of carbohydrates (starch accumulation as well as synthesis/decomposition of water-soluble carbohydrates) could be followed sensitively by monitoring these three different regions of NIR spectra. Carbohydrate I represents the effect of starch accumulation during maturation based on the vibrations of intermolecular hydrogen bonded O-H groups in polysaccharides. Carbohydrate II is the manifestation of O-H stretching and C-C stretching vibrations existing unengaged in water-soluble carbohydrates whileCarbohydrate III describes the changes in C-H stretching and deformation band of poly-and mono-oligosaccharides. NIR spectroscopic techniques are shown to be effective in monitoring plant physiological processes and the spectra have hidden information for predicting the stage of growth in wheat seed.

Investigations of Native and Resistant Starches and Their Mixtures Using Near-Infrared Spectroscopy

“…1c, d) have two peaks between 2,080-2,130 nm. These results are in agreement with the observation of Gergely and Salgó (2005) who stated that the first peak (around 2,096 nm) is determining in the presence of amylose while the second peak (around 2,120 nm) belongs to amylopectin. The decreasing amylopectin concentration of the samples can be followed up in the spectra of the MH (Fig.…”

“…We analysed the whole spectra and the four most characteristic absorption bands for carbohydrates (Gergely and Salgó 2005;Osborne and Fearn 1986;Williams 2001), namely carbohydrate I (1,575-1,590 nm, the first overtone of O-H stretching), carbohydrate II (2,080-2,130 nm, the combination of O-H bending and C-O stretching), carbohydrate III (2,275-2,290 nm, the combination of O-H stretching and C-C stretching) and carbohydrate IV (2,310-2,335 nm, the combination of C-H bending and C-H stretching). The carbohydrate II and III bands provided the most comparable and changeable regions of the samples; therefore, they are shown in this paper.…”

“…The physicochemical and chemical characteristics of starches can be analysed using near-infrared (NIR) spectroscopy as well. NIR spectroscopy is used for the analysis of starch bonds vibrations and damage (Gergely and Salgó 2005;Osborne and Fearn 1986) and it is also possible to evaluate the structural changes in retrograded resistant starch during storage (Garcia-Rosas et al 2009). However, the spectra of resistant starches have not been analysed yet.…”

Monitoring water uptake in whole barley (Hordeum vulgare L.) grain during steeping using near infrared reflectance spectroscopy

“…The region between 2200 and 2300 nm is related with C-H and CONH 2 associated with several compounds including protein, starch and cell wall constituents (e.g. lignin) (Gergely and Salgo, 2005;Jacobsen et al, 2005;Ridgway et al, 1999;Workman and Weyer, 2008). Table 3 shows the calibration statistics for the PLS models developed for water uptake and steeping time using whole barley samples and NIR spectra after second derivative as pre-processing.…”

“…The main differences were observed in the NIR regions between 1100 and 1200 nm, related with C-H second overtones and between 2100 and 2300 nm with related with C-H, O-H stretching, C-C stretching bonds, and CONH 2 associated with several chemical constituents present in the whole barley matrix (e.g. starch) (Alencar-Figueredo et al, 2006;Delwiche et al, 1995;Gergely and Salgo, 2005;Hodsagi et al, 2012;Jacobsen et al, 2005;Workman and Weyer, 2008). Arngren et al (2011)) using hyper spectral NIR imaging of single kernels found that wavelengths between 1400 and 1550 nm can be associated with water activity related to barley germination as well as with the activity of starch and maltose.…”