Determination of amylose content in starch using Raman spectroscopy and multivariate calibration analysis

Abstract

Fourier transform Raman spectroscopy and chemometric tools have been used for exploratory analysis of pure corn and cassava starch samples and mixtures of both starches, as well as for the quantification of amylose content in corn and cassava starch samples. The exploratory analysis using principal component analysis shows that two natural groups of similar samples can be obtained, according to the amylose content, and consequently the botanical origins. The Raman band at 480 cm(-1), assigned to the ring vibration of starches, has the major contribution to the separation of the corn and cassava starch samples. This region was used as a marker to identify the presence of starch in different samples, as well as to characterize amylose and amylopectin. Two calibration models were developed based on partial least squares regression involving pure corn and cassava, and a third model with both starch samples was also built; the results were compared with the results of the standard colorimetric method. The samples were separated into two groups of calibration and validation by employing the Kennard-Stone algorithm and the optimum number of latent variables was chosen by the root mean square error of cross-validation obtained from the calibration set by internal validation (leave one out). The performance of each model was evaluated by the root mean square errors of calibration and prediction, and the results obtained indicate that Fourier transform Raman spectroscopy can be used for rapid determination of apparent amylose in starch samples with prediction errors similar to those of the standard method.

Biodegradable starch-based films containing saturated fatty acids: thermal, infrared and raman spectroscopic characterization

“…The Raman band at 1260 cm -1 attributed to CH 2 OH, which indicates the V-form amylase deformation [22,23] . The vibrations from the glycosidic linkage observed in the region of 920-960 cm -1 , in our study the band at 940 cm -1 [21,24] .…”

Plasticizers effect on native biodegradable package materials

“…The bands from 2900 cm −1 are related to the symmetrical and anti-symmetrical CH stretching vibrations [1,11] and their intensity can be attributed to the amount of amylose and amylopectin [23].…”

“…The 1461 cm −1 band corresponds to the superposition of CH, CH 2 and C-O-H bending vibrations [24] and those from 1380 cm −1 and 1340 cm −1 are due to C-O-H deformation modes and to the superposition of C-O stretching and C-O-H deformations, respectively [1,25].…”

“…Starch is used as the main component of biodegradable packaging materials and also in the textile and the food industry [1][2][3]. Chemically, the starch contains two glucose polymers, amylose and amylopectin, and physically, it has both amorphous and crystalline regions [4].…”

“…Many physical-chemical characteristics and properties of starch as viscosity, gelation power, adhesion etc., are strongly influenced by the amylose to amylopectin ratio [1,6]. The plasticizers molecule (water, glycerol) and other proceedings as annealing extrusion or enzymatic digestion can destabilize the crystalline regions and increase the amorphous domains [7,8].…”