Chemistry Reference
In-Depth Information
Table 1.2 Approved Methods for Nondigestible Carbohydrates
Method Number
AoAC
AACC
Method Name
997.08
32-31
fructans in food Products, ion exchange Chromatographic
Method (Hoebregs, 1997)
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999.03
32-32
Measurement of total fructan in foods by enzymatic/
spectrophotometric Method (McCleary et al., 2000)
16
2000.11
32-28
Polydextrose in foods, ion Chromatographic Method (Craig et al.,
2001)
12
2001.02
32-33
determination of
trans
-galactooligosaccharides in selected food
Products by iC (slegte, 2002)
13
2001.03
32-41
determination of resistant Maltodextrins and total dietary fiber in
selected foods by LC-enzymatic-gravimetric Method (gordon
and ohkuma, 2002)
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recovered along with the insoluble fraction via filtration. There are, however, certain
naturally occurring or manufactured oligosaccharides and polysaccharides, that is,
nondigestible carbohydrates, that remain soluble in the dilute alcohol medium and,
hence, are not recovered as part of the TDF residue. Since 1997, methods have
been developed and approved by AOAC and AACC for separate determinations
of fructans and fructo-oligosaccharides, polydextrose, galacto-oligosaccharides,
and resistant maltodextrins (Table 1.2). In 2002, the Institute of Medicine of the
National Academy of Sciences
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proposed a definition stating:
Dietary Fiber
consists of nondigestible carbohydrates and lignin that are intrinsic and
intact in plants.
Functional Fiber
consists of isolated, nondigestible carbohydrates that
have beneficial physiological effect in humans.
Total Fiber
is the sum of Dietary Fiber
and Functional Fiber.
If and when the above definition is accepted by the FDA, the scientific community,
and consumers, then the existing analytical methods need to be modified to measure
all the components as defined above.
1.2 ANAlyTICAl ProCEDurEs For ToTAl DIETAry FIbEr
The approved methods can be classified as either gravimetric or chemical pro-
cedures. Regardless of this distinction, all ground, dried food samples containing
>10 percent fat and/or sugar, should be extracted sequentially with hexane or petro-
leum ether to remove fat, and with 80 percent ethanol or methanol to remove sugar.
Detailed descriptions of each method under discussion can be found in an AOAC
publication.
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