Measurement of total starch in cereal products by amyloglucosidase-alpha-amylase method: collaborative study.
McCleary, B. V., Gibson, T. S. & Mugford, D. C. (1997). Journal of AOAC International, 80, 571-579.
An American Association of Cereal Chemists/AOAC collaborative study was conducted to evaluate the accuracy and reliability of an enzyme assay kit procedure for measurement of total starch in a range of cereal grains and products. The flour sample is incubated at 95 degrees C with thermostable alpha-amylase to catalyze the hydrolysis of starch to maltodextrins, the pH of the slurry is adjusted, and the slurry is treated with a highly purified amyloglucosidase to quantitatively hydrolyze the dextrins to glucose. Glucose is measured with glucose oxidase-peroxidase reagent. Thirty-two collaborators were sent 16 homogeneous test samples as 8 blind duplicates. These samples included chicken feed pellets, white bread, green peas, high-amylose maize starch, white wheat flour, wheat starch, oat bran, and spaghetti. All samples were analyzed by the standard procedure as detailed above; 4 samples (high-amylose maize starch and wheat starch) were also analyzed by a method that requires the samples to be cooked first in dimethyl sulfoxide (DMSO). Relative standard deviations for repeatability (RSD(r)) ranged from 2.1 to 3.9%, and relative standard deviations for reproducibility (RSD(R)) ranged from 2.9 to 5.7%. The RSD(R) value for high amylose maize starch analyzed by the standard (non-DMSO) procedure was 5.7%; the value was reduced to 2.9% when the DMSO procedure was used, and the determined starch values increased from 86.9 to 97.2%.
Measurement of carbohydrates in grain, feed and food.
McCleary, B. V., Charnock, S. J., Rossiter, P. C., O’Shea, M. F., Power, A. M. & Lloyd, R. M. (2006). Journal of the Science of Food and Agriculture, 86(11), 1648-1661.
Procedures for the measurement of starch, starch damage (gelatinised starch), resistant starch and the amylose/amylopectin content of starch, β-glucan, fructan, glucomannan and galactosyl-sucrose oligosaccharides (raffinose, stachyose and verbascose) in plant material, animal feeds and foods are described. Most of these methods have been successfully subjected to interlaboratory evaluation. All methods are based on the use of enzymes either purified by conventional chromatography or produced using molecular biology techniques. Such methods allow specific, accurate and reliable quantification of a particular component. Problems in calculating the actual weight of galactosyl-sucrose oligosaccharides in test samples are discussed in detail.
Chemical composition and physicochemical properties of tubera salep produced from some Orchidaceae species.
Tekinşen, K. K. & Güner, A. (2010). Food Chemistry, 121(2), 468-471.
Salep samples obtained from 10 different Orchidaceae spp., namely Dactylorhiza osmanica var. osmanica, Ophrys mammosa, Orchis anatolica, Orchis coriophora, Orchis italica, Orchis morio, Orchis palustris, Orchis simia, Orchis tridentata and Serapias vomeracea ssp. orientalis, in Anatolia, were analyzed for moisture, glucomannan, starch, protein, ash contents, pH and viscosity values. Depending on the species, the samples showed statistically significant differences in glucomannan, starch and viscosity values. It was observed that the salep samples obtained from the tubers of O. italica, O. morio, O. anatolica and O. tridentata and S. vomeracea ssp. orientalis, respectively, had higher glucomannan contents and viscosities. To ensure a supply of high-quality salep, the uncontrolled collection of tubers from the wild, especially the species O. italica, O. morio and O. anatolica, should be prevented, and research into methods of cultivation should be carried out.
Structure and bioactivity of the polysaccharides in medicinal plant Dendrobium huoshanense.
Hsieh, Y. S. -Y., Chien, C., Liao, S. K. -S., Liao, S. F., Hung, W. T., Yang, W. B., Lin, C. C., Cheng, T. J. R.,Chang, C. C., Fanga, J. M. & Wong, C. H. (2008). Bioorganic & Medicinal Chemistry, 16(11), 6054-6068.
Detailed structures of the active polysaccharides extracted from the leaf and stem cell walls and mucilage of Dendrobium huoshanense are determined by using various techniques, including chromatographic, spectroscopic, chemical, and enzymatic methods. The mucilage polysaccharide exhibits specific functions in activating murine splenocytes to produce several cytokines including IFN-γ, IL-10, IL-6, and IL-1α, as well as hematopoietic growth factors GM-CSF and G-CSF. However, the deacetylated mucilage obtained from an alkaline treatment fails to induce cytokine production. The structure and bioactivity of mucilage components are validated by further fractionation. This is the first study that provides clear evidence for the structure and activity relationship of the polysaccharide in D. huoshanense.
Methodologies for the extraction and analysis of konjac glucomannan from corms of Amorphophallus konjac K. Koch.
Chua, M., Chan, K., Hocking, T. J., Williams, P. A., Perry, C. J. & Baldwin, T. C. (2012). Carbohydrate Polymers, 87(3), 2202-2210.
Here we present a comparison of commonly used methodologies for the extraction and quantification of konjac glucomannan (KGM). Compositional analysis showed that the purified konjac flour (PKF) produced using a modified extraction procedure contained 92% glucomannan, with a weight average molecular weight (Mw), polydispersity index (PDI) and degree of acetylation (DA) of 9.5 ± 0.6 × 105 g mol-1, 1.2 and 2.8 wt.%. These data, plus Fourier-transform infrared spectral (FTIR) and zero shear viscosity analyses of the extract (PKF) were all consistent with the literature. Comparison of three existing methodologies for the quantitative analysis of the KGM content of the PKF, namely 3,5-dinitrosalicylic acid (3,5-DNS), phenol–sulphuric acid and enzymatic colorimetric assays; indicated that the 3,5-DNS colorimetric assay was the most reproducible and accurate method, with a linear correlation coefficient of 0.997 for samples ranging from 0.5 to 12.5 mg/ml, and recoveries between 97% and 103% across three spiking levels (250, 500 and 750 μg/g) of starch. These data provide the basis of improved good laboratory practice (GLP) for the commercial extraction and analysis of this multifunctional natural polymer.