2.4. Perten Fungal (α-Amylase)
Falling Number (FFN)
In the past, systematic documentation of the addition of enzymes, for
example for flour improvement, by the standard falling-number method presented
certain problems. The problems were greater when fungal α-amylase was used than
with α-amylase concentrates obtained from cereals (malt flour). In tests on treated
and untreated milled products it was possible to trace these changes better
with the Brabender Amylograph, particularly with the maximum viscosity
(Brümmer, 1984a).
The new development by Perten Instruments is a modified Falling Number
method that uses the ability of amylases to liquefy gelatinized starch and
therefore to reduce measurable viscosities. The material used is a suspension of
potato starch in a buffer solution (pH 5.3, as in the swelling curve after
Drews (1971), to which the milled product to be tested, enzyme preparations or
other relevant raw materials are added. Preparation of the sample to be tested
and measurement of the changes in viscosity are then carried out much as in the
familiar standard Falling Number method.
Both cereal and fungal amylases can be detected by this modified
method. Since the fungal amylases are inactivated at lower temperatures than
the cereal amylases, it is possible to differentiate between them. The
influence of "side activities" such as xylanase or protease is
usually slight, although these may alter the Falling Number at least if the
dose is too high. But the FFN did seem to react sensitively to different
flours, i.e. if the same enzyme preparations were used on flours from different
wheat varieties and these were subsequently tested. This may be due to
differences in the susceptibility of the ingredients to enzymatic attack.
All in all it may be said that the enzymatic changes in raw materials
could still be detected better and with greater differentiation by the maximum
viscosity of the Brabender Amylogram curves than by various Falling Number
methods. However, the Brabender Amylogram only records total activity and
cannot help to distinguish between cereal and fungal amylase as the modified
Perten Falling
Number method does.
Further series of tests need to be performed to establish how far
microbial contamination of cereal, e.g. with fusaria, can be determined
directly or by comparison with the standard Falling Number. Washings from
deliberately contaminated cereal have so far shown only slight effects on the
measurements. It was concluded from this that the enzymatic activity of fusaria, for example,
is only slight. It was not possible to decide whether or not a sample was
contaminated with fusaria or whether technological effects can be expected to
result from the micro-organisms.
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