Chemistry Reference
In-Depth Information
and lactose are determined before and after enzyme hydrolysis, and their concentra-
tions are used to calculate the total TGOS content of the test samples.
1.3.2 high-Performance liquid Chromatographic Method
1.3.2.1 For Resistant Maltodextrins
Resistant maltodextrins (RM) are mixtures of oligo- and polysaccharides pro-
duced by a combination of heat and enzyme treatment of cornstarch with a wide
range of molecular weight averaging about 2,000. The lower-molecular-weight frac-
tion is soluble in dilute alcohol. The AOAC method 2001.03
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measures first a non-
digestible carbohydrate fraction recovered from 78 percent alcohol solution using
AOAC method 985.29. Then the dilute alcohol filtrate is concentrated on a rotary
evaporator, and passed through ion exchange resins for the removal of salts and
proteins. Low-molecular-weight RM is quantified by HPLC with reflective index
detector. This method measures both the dilute alcohol soluble and insoluble nondi-
gestible carbohydrates.
1.3.2.2 For Lactulose
Using a Waters carbohydrate analysis column, separation and quantification of a
solution containing galactose, tagatose, lactose, and lactulose was achieved by elu-
tion with a mixture of water and acetonitrile as described by Parrish et al.
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This is
not an official method; however, it is applicable for the analysis of samples contain-
ing mono- and disaccharides.
1.3.3 spectrophotometric Method
1.3.3.1 For Total Fructan
AOAC method 999.03
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incorporates enzyme treatments with spectrophotomet-
ric determination for the measurement of fructan and fructo-oligosaccharides. Test
samples are extracted into hot water (80°C) with pH maintained above 5.5. Extracts
are incubated with a solution of sucrase/amylase, followed by reduction with sodium
borohydride. The mixtures containing sugar alcohol are then incubated with fruc-
tanase, followed by the addition of PAHBAH (p-hydroxybenzoic acid hydrazide)
reagent and the absorbance is measured at 410 nm against a reagent blank. Total
fructan content is calculated from the concentration of fructose in the hydrolyzate.
1.3.4 Fourier Transform Ion Cyclotron resonance Mass spectrometry
1.3.4.1 For Fructo-Oligosaccharides
(
FOS
)
A relatively new method
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for precise quantification of fructo-oligosaccharides
has been published utilizing matrix-assisted laser desorption/ionization Fourier
