|
There
are many different types of fiber determinations: Crude Fiber, Acid
Detergent Fiber (ADF), Neutral Detergent Fiber (NDF), and dietary fiber.
The first three can be determined on the Fibertec M 1020, the
Fibertec
2010 and the
FiberCap 2021 and
2023. Dietary fiber can be determined on
the
Fibertec E
1023.
Crude
Fiber – Weende Method [Fibertec
1020,
2010,
2021,
2023]
The
Weende Method for determining crude fiber is a very old procedure that is
used in animal feed formulations. It is defined as the residue of plant
cells after extraction by acid and alkaline hydrolysis. In the standard
procedure for crude fiber determination, the sample is first boiled in
dilute acid and then in dilute alkali. The acid hydrolysis removes free
sugars and starch. The alkaline hydrolysis removes protein and some
carbohydrates. This process also removes some hemi-cellulose and lignin;
therefore, only partial recovery of fiber components is achieved. Due to
the long-history of this method, estimates of nutritive value and quality
can be made despite the following recovery rates: Hemi-cellulose 20-30%,
Cellulose 50-80%, Lignin 10-50%
Detergent
Fiber – Van Soest [Fibertec 1020,
2010,
2021,
2023]
Detergent
fiber analysis of forage and feed samples is performed for use in the
determination of the energy value of the feed/forage. The procedure is
similar to crude fiber except detergent reagents are used.
Detergent
fiber is defined as the residue of plant cells after fractionation using
detergent solutions for the solubilization of protein and starch. When an
acid detergents solution (ADS) is used to determine acid detergent fiber,
100% of the cellulose and lignin is recovered. If neutral detergent
solution (NDS) is used to determine neutral detergent fiber, 100% of the
hemi-cellulose, cellulose and lignin are recovered.
Dietary
or Enzymatic fiber is used to determine fiber values for human foods. It
is defined as the remnants of plant cells resistant to the alimentary
enzymes of humans. Digesting and filtering out non-fibrous components with
specific enzymes determine dietary fiber. Soluble components are
precipitated with alcohol.
The
procedure involves three incubations with enzymes that mimic the human
digestive system. As with crude fiber, the residual material is ashed and
weighed, and a dietary fiber number is calculated.
PRODUCT
COMPARISON
FiberCap
(2021,
2023)
The
FiberCap 2021 and 2023 are low-cost manual systems handling batches of 6
or 18 samples at once. The sample is weighed into a FiberCap, a
polyprolylene container with a snap lid, where it remains for the entire
analysis. Using handling devices, the samples are easily defatted and the
digestion steps are performed in the extraction vessel on a hotplate.
Fibertec
M (1020)
The
Fibertec M is a manual instrument for analyzing 6 samples at once.
Reagents are heated on a hot plate to 80 ºC before they are introduced to
the samples. The sample is weighed into a fritted glass crucible where it
remains for the entire analysis. Because there are no transfer sample
steps, Fibertec units show good reproducibility. The digestion steps are
performed with a side-heating element that reduces charring of the sample.
Samples are filtered with a 4-postion filtration system that includes
vacuum and pressure to dislodge the sample if clogging occurs.
Fibertec
(2010)
The
Fibertec 2010 is a semi-automated instrument that simplifies the
determination of crude fiber, ADF, and NDF. In addition to the benefits of
Fibertec M, it heats the reagents in an integrated, closed system before
they are added to the sample. It also has an internal rinse water system.
Fibertec
E
(1023)
Filtrations
with dietary fiber samples are usually difficult. The samples tend to form
gelatinous precipitates and clog filtering systems. The Fibertec E has the
same pressure/vacuum style of filtration as found in the Fibertec I and M
to minimize filtration time. The filtration unit filters 6 samples at a
time.
The
Fibertec E also includes a Shaking Water Bath that incubates up to 12
samples at one time. The temperature range is from ambient to 80 ºC; it
is possible to preset three temperatures. The shaking speed and amplitude
are continuously adjustable.
Foss
has an extensive library of Fibertec Applications available.
A few of these applications are listed here for easy reference.
|
Applications
