Studies on Barley and Malt With the Rapid Viscoanalyser: [I] the Effect of Variations in Physical and Chemical Parameters

Rapid Viscoanalysis was investigated as a method off determining the malting quality of barley and malt, to define the conditions required to select progeny with high malting potential from a barley breeding programme. Studies were made on (i) varying physical parameters and chemical additions, (ii) the effect of modification, (iii) the prediction of malting potential from viscograms, (iv) the relationship of the viscometric characteristics of starch to malting quality and (v) the use of a Rapid Viscoanalyser (RVA) in a commercial meltings. The results will be presented as a series of papers. In this paper, physical and chemical factors were examined. Firstly, sample/liquid ratios, initial and final temperatures, speed off mixing and the fineness of grinding of the samples were varied. The effect of the time of standing of malt slurries was also investigated. The peak areas, peak viscosities and Stirring Numbers were shown to obey a relationship with the cube of the sample concentration under a wide range of conditions. Comparisons with the Amylograph and Falling Number Apparatus are reported. Conditions of grinding, temperature, speed of mixing and grist/liquid ratios for the routine examination of barleys and malts were defined. Secondly, calcium-complexing agents, acids, alkalies and the salts of heavy metals were tested for their effects on the Rapid Viscogram of malt. Unless substantial time was allowed for reaction to occur, calcium-complexing agents per se had no effect on viscograms: acidic radicles were necessary. Although both acids and alkalies affected viscograms, inhibition could be reversed by neutralisation. Silver nitrate is suggested as the most suitable chemical for inhibition of enzymes for the determination of the intrinsic viscosity of malts with an RVA.