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Using the Rapid Visco analyser to measure fungal alpha-amylase activity. A. LEUNG (1), M. L. Bason
(1), and R. I. Booth (1). (1) Newport Scientific, 1/2 Apollo St. Warriewood NSW 2102 Australia.
In the baking industry cereal and fungal alpha-amylases are used to
improve fermentation of flour and to retard staling. Cereal alpha-amylase is conventionally detected with
the Brabender Amylograph, by the Falling Number method at 100°C or with the Rapid Visco Analyser
(RVA) Stirring Number method at 95°C. However, fungal alpha-amylase cannot be detected by these
methods because it has low thermostability. The aim of the work presented here was to develop a rapid and
simple viscometric method using the RVA to measure fungal alpha-amylase activity in supplemented bakers
flour, premixes and concentrates. An agglomerated, cold water soluble, modified waxy maize corn starch
was used as substrate. Fungal alpha-amylase flour supplementation was measured at 50°C, using 4.00 g of a
50:50 mixture of flour and substrate and 25 mL of distilled water. Fungal alpha-amylase in premixes and
concentrates was extracted with a acetate buffer and the activity measured at 50°C, using 2.00 g substrate
and a total of 25 mL acetate buffer extract. Results were obtained in 20 minutes. End viscosities were well
correlated with SKB values and other measures of fungal alpha-amylase activity. The method is simple to
perform and has been optimised for sensitivity at commercial dosage levels. It is suitable for use to measure
and control fungal alpha-amylase supplementation and levels in premixes and concentrates.
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