Differentiation of Carbohydrate Gums and Mixtures Using Fourier Transform Infrared Spectroscopy and Chemometrics

Abstract

Guar gum, a nonionic galactomannan, is used as an economical thickener and stabilizer in the food industry and is often combined with xanthan, locust bean gum (LBG), or carboxymethylcellulose (CMC) to promote synergistic changes in viscosity or gelling behavior via intermolecular interactions; however, the adulteration of LBG with guar gum is a well-known industrial problem. The ability to identify the purity of gums and concentrations of individual gums in mixtures would be advantageous for quality control in the food industry. Fourier transform infrared spectroscopy (FTIR) methods are rapid and require minimum sample preparation. The objectives of this study were to evaluate the ability of FTIR techniques to (1) differentiate LBG with a variety of mannose/galactose (M/G) ratios, (2) differentiate guar, LBG, tara, and fenugreek gums, (3) differentiate pure guar gum from guar gum mixed with LBG, xanthan gum, or CMC, (4) quantify LBG, xanthan gum, and CMC in guar gum, and (5) quantify guar gum in LBG. Two FTIR methods were used: diffuse reflectance (DRIFT) on powdered gum samples added to KBr at 5%, w/w, and attenuated total reflectance (ATR) on 1%, w/w, gum solutions. Spectra were collected and then analyzed by multivariate statistical procedures (chemometrics). The DRIFT method provided better discrimination and quantitative results than the ATR method. Canonical variate analysis (CVA) of DRIFT spectra (1200-700 cm(-1)) was able to classify LBG with various M/G ratios, pure galactomannans, and pure versus mixtures of gums with 100% accuracy. Quantification of an individual gum in gum mixtures (0.5-15%, w/w) was possible using partial least-squares (PLS) analysis of DRIFT spectra with R2 > 0.93 and using this approach for quantifying guar gum added to LBG resulted in an R2 > 0.99, RMSEC = 0.29, and RMSEP = 3.31. Therefore, the DRIFT FTIR method could be a useful analytical tool for quality control of select gums and gum mixtures used in the food industry.

Mesquite Gum as a Novel Reducing and Stabilizing Agent for Modified Tollens Synthesis of Highly Concentrated Ag Nanoparticles

“…The bands around 1150 cm −1 and 900 cm −1 can be attributed to vibration modes of C–O and the C–O–H groups of carbohydrates (such as glucose, mannose and galactose), according to the literature [31,52,53,54]. The bands at 834 and 776 cm −1 indicate the occurrence of pyranose glycosidic acetal groups [54]. A shift in the absorbance peaks was observed (Figure 4B) from 3290 to 3226 cm −1 and from 2922 to 2917 cm −1 , suggesting the binding of silver with hydroxyl and carboxylate groups.…”

Structural and thermal characterization of galactomannans from non-conventional sources

“…7 shows the FTIR spectrum of the analyzed galactomannans. The IR spectra of galactomannans show peaks at 815 and 872 cm −1 that are related with the presence of anomeric configurations (␣ and ␤ conformers) and glycosidic linkages, attributed to ␣-d-galactopyranose units and ␤-d-mannopyranose units, respectively (Figueiró, Góes, Moreira, & Sombra, 2004;Prado, Kim, Özen, & Mauer, 2005;Yuen, Choi, Phillips, & Ma, 2009). The broad band between 1198 and 983 cm −1 results from the stretching vibration of C-O in C-O-H bonds (e.g.…”

Carboxymethylation of Cassia angustifolia seed gum: Synthesis and rheological study

“…The absorption band at 1437 cm −1 belongs to CH 2 group bending while the presence of strong peak 1024 cm −1 was observed due to the bending H 2 C O CH 2 bond. The peaks at 869 and 813 cm −1 were related with the presence of glycosidic linkages and anomeric configurations (␣-and ␤-conformers), attributed to two sugar units, respectively (Figueiró, Góes, Moreira, & Sombra, 2004;Prado, Kim, Özen, & Mauer, 2005;Yuen, Choi, Phillips, & Ma, 2009). The IR spectrum of CM-CAG ( Fig.…”