Attenuation control


Attenuation is a key factor for the daily operations of a brewhouse, where RDF and ADF are used to describe the degree of fermentation of the worts produced. Measuring attenuation is important as brewers need to meet recipe specifications, and because different beer styles come with specific attenuation levels. An example is the production of low-calorie beers, also known as light beers, which have a high degree of attenuation requiring the use of exogenous glucoamylases.

However, it is somewhat challenging for the brewer to achieve predictable and targeted attenuation specifications. Not only the mashing parameters will influence the final degree of fermentation of the wort, but also malt quality will have a direct impact on this. Both malt gelatinization and diastatic power will have a saying in the attenuation of the wort, and often brewers need to cope with the fluctuating quality of the crop.

For this matter, the use of exogenous enzymes like glucoamylases has become a common practice to control attenuation, even when not producing high attenuation beers. Several factors will have an impact on the attenuation while using enzymes: type of enzymes, the enzymatic stability during the mashing process, and the mashing temperature and time. The complexity of accounting for all of these factors hence makes it complicated for the brewer to have full control over which enzymes to use, the necessary dosages, and how to compensate for the inherent variability of the malt quality.


With the Specshell In-line Brewing Analyzer (SIBA), the brewer can now have full control over the attenuation when using exogenous enzymes like glucoamylases. SIBA gives a live overview of the enzymatic activity using the degree of polymerization, glucose, and maltose and maltotriose concentrations of the mash. Based on these live parameters, the brewer can evaluate if the enzymatic activity is sufficient to achieve the targeted attenuation, or be critical about the enzymatic dosage used and meet the target without overdosing. The use of SIBA has become even more relevant with the current fluctuating malt quality, where the analyzer can be used as a warning to increase the glucoamylase dosages when the Fermentability Tool detects a decrease in the targeted attenuation without the need for any laboratory analysis.

A real case of how SIBA can help adjust the glucoamylase dosage to meet your target RDF. Both glucoamylase dosages – high and low – reach the same final RDF and glucose concentrations after mashing. The lower dosage conversion speed is lower as the enzyme is more limited, but the target RDF is equally reached avoiding the brewer to waste their enzyme bill.

Proper control of the attenuation in your brewery is now possible by taking the best out of your enzymes together with SIBA. 

For more information, book a meeting with our specialists. 

Pasting temperature, the key for dynamic mashing.

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:

The solution for 2021 challenging malt

Climate effects on malt quality:

Through the last few years, different barley producing regions have been experiencing unusual drought. The dry and hot summer of 2021 had a devastating effect on the worldwide barley crop [1,2,3]. To add insult to injury, the effect on barley yields and malt prices might in fact not even be the most significant impact for the brewer. Heat and drought will shift gelatinization temperatures to higher temperatures [4,5,6]. Recent results supports that barley gelatinization temperatures are mostly determined growth conditions and very little by genetics.

If starch gelatinization temperature is much higher than saccharification rest temperature, it will cause trouble to the brewer. This is because that, the last starch fraction will gelatinize very slow during the saccharification starch gelatinizing very late in the mashing process, cannot be hydrolyzed by β-amylase which is inactivated at the end of the mashing process. This will in most cases it will result in a lower wort attenuation, but in some very extreme cases this late gelatinization can even result in filtration issues because of large unhydrolyzed starch molecules. While most brewers have designed mashing recipes to be well above the 60-63C temperature often cited, gelatinization temperatures from heat and drought stress barley will have significantly higher gelatinization temperature. In this case, the wort quality would benefit by a higher saccharification temperature.

However, this theory is currently is tricky for the brewer to apply; The malt producers do not routinely supply this parameter in the malt specification, and very few breweries have resources to routinely run RVA analysis on all incoming malt. This unknown change in malt quality introduced by “random” barley origins can cause batches with “identical” specifications (variety, malting, supplier) to cause sudden and unexplainable drops in wort quality.

High gelatinization malt will result in:

• Late extract formation
• RDF compromised


SIBA for RDF consistency - no matter malt quality:

Specshell assisted a European brewery with inline SIBA measurements of their production while experiencing unexpected malt quality fluctuation. By monitoring the malt gelatinization over this period, the brewery had troubles with RDF fluctuations and low wort attenuation in some production weeks. SIBA found the gelatinization temperature of the malt used, extraordinary high at 66.5C - more than one degree higher than the recipe saccharification rest temperature. By adjusting saccharification temperatures, the RDF of the wort was increased by more than 2%, ensuring the brand attenuation consistency. With the subsequent batch of malt, the gelatinization temperature returned to an ideal 61C, SIBA notifying the brewer to lower the saccharification temperature slightly again to obtain optimal B-amylase stability.

These results show how much brewers can benefit from inline measurements, that will give the a prompt warning if malt quality undergo changes, and allow the to work with difficult crops. Despite involvement of advanced barley breeding programs and good supply chain control, malt quality is largely determined by random regional weather conditions. We envision that the future of mashing will not be based on a static recipe but rather a dynamic mashing scheme adjusting temperatures according to in-line and real time data provided automatically to the brewer.



[1] Simpsons Malt (November 1, 2021) ( [2] Brewers Association (November 1, 2021) ( [3] Bryce, J. (Host) (October 25, 2021) Episode 228: The Challenging 2021 Barley Outlook ( [4] Ao Z.; Jane J. L., (2007). Carbohydr Polym; 67: 46-55 [5] Myllarinen P.; Schulman A A; Salovaara H; Poutanen K (1998) Acta Agricultural Scandinavia; Section B; Soil Plant Sci; 48: 85-90 [6] Tester R.F.; South J. B.; Morrison W.R., Ellis R.P. (1991). J Cereal Sci, 13: 113-127 [7] van Grunsven C.; Kunov-Kruse A.; J Grønborg; Lekuona


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