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FAILURE OF MERCURIC CHLORIDE TO SELECTIVELY INHIBIT β‐AMYLASE IN SORGHUM MALT
Author(s) -
Robbins D. J.,
Egan B.
Publication year - 1992
Publication title -
journal of the institute of brewing
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.523
H-Index - 51
eISSN - 2050-0416
pISSN - 0046-9750
DOI - 10.1002/j.2050-0416.1992.tb01120.x
Subject(s) - amylase , sorghum , chemistry , chloride , food science , context (archaeology) , biochemistry , chromatography , enzyme , agronomy , organic chemistry , biology , paleontology
Mercuric chloride has been reported to be a suitable reagent for the determination of α‐amylase activity in sorghum malt, based on its ability to selectively inhibit β‐amylase. In this re‐investigation, the α‐ and β‐amylase activities of eight sorghum malts were determined after treatment of malt extracts with various concentrations of mercuric chloride. At a malt: mercuric chloride ratio of 8.3 × 10 3 : 1, incomplete inhibition of β‐amylase activity, as measured by the Betamyl assay, occurred in all extracts. However, this concentration resulted in significant inhibition of α‐amylase activity in all extracts, as measured by both the Ceralpha assay and the Phadebas assay. In addition, α‐amylase activity was found to be significantly inhibited at malt: mercuric chloride ratios as low as 1.0 × 10 5 : 1, when measured by the AmyloZyme assay. These findings do not support the original report that a malt: mercuric chloride ratio of 4.0 × 10 3 : 1 will selectively inhibit β‐amylase in sorghum malt. Furthermore, in this context it should be emphasised that the original report was based upon inhibition studies conducted on β‐amylase derived from barley, not sorghum malt .