Pasting temperature, the key for dynamic mashing.
Gelatinisation or pasting?
In a recent investigation by Rittenauer et al., both terms had been brought up for discussion. To make starch accessible to the amylolytic enzymes, brewers apply a characteristic temperature during mashing to induce swelling and partial disruption of the microscopic starch granules. To date, this temperature has been referred as either gelatinization or pasting temperature. However, Rittenauer et al. address the need of separating both terms, indicating the importance of specifically the pasting temperature to the brewer.
"Pasting summarizes continuing starch transformations occurring at temperatures exceeding the gelatinization temperature. It includes intensive swelling and total disruption of the starch granules in combination with considerable amylose leaching"
describes Rittenauer et al.
The authors also emphasize that besides the genetic endowments, extrinsic factors like growth conditions, influence the pasting temperatures of the malt, bringing heterogeneity to the daily tasks in the brewhouse. The malt pasting temperature fluctuations can be compensated, by adapting the mashing process temperatures. However, this approach must be carefully used, -as malt enzymes, like limit dextrinase and β-amylase, are thermally unstable. Too high temperatures have a drastic impact on saccharification by directly affecting the fermentability of the wort.
The mashing paradox proposes that "the optimal initial mashing temperature should be as high as necessary to ensure quick starch accessibility, but concurrently, as low as possible to preserve the activity of thermolabile enzymes as long as possible. Up to now this optimal process temperature, considering fluctuating raw material properties, has been unknown and therefore was not applied in breweries and distilleries."
However, the development of new inline technologies like SIBA, -Specshell's Inline Brewing Analyser, has removed the blindfold, facilitating the brewers a more dynamic mashing practice. SIBA automatically depicts the pasting profile directly during the brewing process, allowing the brewer to instantly act by adjusting the mashing temperature. The brewer can now simply modify process temperature based on actionable data provided by SIBA and then monitor the impact in real-time, thereby avoiding prolonged brewhouse challenges. If malt batches with increased pasting properties are processed without adaption of the saccharification temperature, this will result in reduced sugar and alcohol yields, and potentially filtration problems.
The author concludes by saying "Overall, the results speak in favour of applying a raw material adapted initial mashing temperature and point out that it is important to differentiate between the terms gelatinization and pasting of malt starch. As saccharification requires intense starch granule swelling followed by disruption and amylolytic degradation, only the term pasting is appropriate in this context."
Rittenauer M., Gladis S., Gastl M., Becker T. (2021), Gelatinization or Pasting? The Impact of Different Temperature Levels on the Saccharification Efficiency of Barley Malt Starch, [article] MDPI. Available at: https://www.mdpi.com/2304-8158/10/8/1733