Optimized analytical parameters for the viscometric determination of pasting temperatures of barley malt

Rittenauer, Michael; Gastl, Martina; Becker, Thomas

doi:10.1016/j.foodhyd.2016.07.033

Cited by 9 publications

(12 citation statements)

References 35 publications

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“…In contrast to the maximal peak viscosity, the initial viscosity was independent of the α ‐amylase activity of the respective malt. This circumstance might be explained by the resistance of still unpasted starch granules towards enzymatic hydrolyses .…”

Section: Resultsmentioning

confidence: 99%

“…Viscometric analyses were carried out using a ‘Super 4 Rapid‐Visco‐Analyser’ (Perten Instruments, PerkinElmer Company, USA). A malt‐specific procedure with optimized parameters was used to record the viscometric progression of the samples .A 6.25 g aliquot of malt flour, based on a moisture content of 5%, was mixed with distilled water in an RVA sample can. The accurate weight of malt is dependent on the water content and can be calculated as follows:

m_{m} = \frac{95^{*} m_{i}}{(100 - w_{m})}

…”

Section: Methodsmentioning

confidence: 99%

“…In order to fill this gap, an adapted viscometric method with optimized analysis parameters was developed : a practical grist to water ratio (1:4) is micro‐mashed in a rotational viscometer (Rapid‐Visco‐Analyser, RVA) while continuously recording the torque applied to the paddle rotating in the fluid .…”

Section: Introductionmentioning

confidence: 99%

“…A slope threshold mPas/s which needs to be reached or exceeded can be specified. The impact of this threshold on the resulting PT was discussed in previous investigations : sensitive thresholds led to a more precise determination of the onset and therefore to more accurate PTs. Too sensitive slopes, however, led to misinterpretations caused by unavoidable viscosity fluctuations prior to starch pasting (see Fig.…”

Section: Introductionmentioning

confidence: 99%

“…) and therefore unrealistically low PTs. In the MEBAK analysis procedure for barley malt, a compromise between accuracy and robustness was investigated and set as threshold (5 mPas in 6 s) .…”

Section: Introductionmentioning

confidence: 99%

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Critical evaluation of viscometrically determined pasting temperatures in barley malt

et al. 2017

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Modern varieties of malting barley allow mashing to proceed efficiently to enable saccharification and other biochemical processes. A prerequisite for starch hydrolysis is the disruption of starch granule structure by exceeding a grain specific pasting temperature. For grains, several viscometric methods based on the Rapid‐Visco‐Analyser were developed to determine variations in the pasting temperature reproducibly. Absolute pasting temperatures, as they are necessary to optimize the isothermal mashing process, cannot be determined owing to constructional and data evaluation related limitations. The aim of this research is to investigate and compensate for temperature deviations caused by standard data evaluation and lagging heat transfer from the heating unit into the sample. Accordingly, an improved determination of the pasting onset and a formula to compensate for temperature lags were developed. The optimized data leads to more accurate and reduced pasting temperatures compared with the standard method. The heat transfer was reproducibly quantified (Δϑ: 2.9–5.8°C) and integrated into a compensation formula (R2 = 0.99). It was found that the lag is strongly dependent on the actual sensor temperature but independent of the unpasted sample's initial viscosity. The results were applied on viscometric analyses (n = 161) to calculate the intrinsic pasting temperatures of barley malt. The determined temperature range is considerably lower than anticipated (56.7–60.5°C). Winter barley exhibits significantly lower pasting temperatures. The outcome of this work can be used to improve the accuracy of prospective analysis and to correct already existing viscometric raw data. Copyright © 2017 The Institute of Brewing & Distilling

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Section: Resultsmentioning

confidence: 99%