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


How can ZYMON facilitate the daily plant management in comparison to HPLC?

Generating detailed and meaningful data in real-time during your process is often the bottleneck to optimization of key operating parameters and daily quality control (QC). Off-line analytical methods such as liquid or gas chromatography (HPLC/GCMS) are often the methods of choice and are indeed valuable for providing detailed compositional analysis, or for ensuring a product meets final QC checks. However, this methods have shortcomings related to sampling, and the calibration and maintenance needed, for not mentioning the limited data frequency and process information obtained.

Process analytical technologies (PAT) on the other hand, offer bioprocess plants the opportunity to gain an unprecedented level of insight into their processes and products. ZYMON in particular has been designed and calibrated to provide the highest level of real-time data for bioethanol processes.

Forget about sampling, calibration and maintenance.

Our patented solutions work inline (no sampling needed), are industrially robust, and require no user calibration (once plugged in, they produce data instantly during the first batch).

ZYMON is more than just an in-line HPLC for the bioethanol processes.

Moreover, the user can experience an automated process information (based on infection alarms and real-time yeast and enzymatic activities), and uninterrupted data every 5 minutes.

ZYMON at 37th FEW

ZYMON at 37th FEW

Interested in knowing more about Actionable In-line Monitoring of Bioethanol Fermentation with ZYMON? Find us on Booth 606 at FEW 2021 (13-15th July, Des Moines). Our VP of Bioethanol Business Unit Steen Skjold-Jørgesen will also be presenting the "Experience with online actionable process monitoring based on MIR", July 14th 3:30 PM.

Experience  with online  actionable process monitoring based  on  Mid Infrared Spectroscopy     

Several attempts have been made to apply IR spectroscopy to online monitoring of fermentation processes. Socalled 'Near Infrared (NIR)' generally fails due to need for frequent recalibration to the specific system being measured. Mid Infrared Spectroscopy provides very distinct information about the molecular species at hand, but the technology has so far been deemed too fragile for industrial application. 

Specshell has developed ZYMON - a robust precalibrated instrument tailored for grain to ethanol fermentation. The instrument provides online actionable information about the early phases of fermentation where intervention is still possible. This paper provides an overview of the technology behind ZYMON, as well as an account of the industrial experience so far. 

The instrument went to work day 1 without a need for plant specific calibration, it measured for months in a row without interruption, and it provided thorough insights with the performance of the process as well as the added ingredients such as yeast and enzymes. Infections were spotted early on as well as deviations from the production protocol around filling, ingredient addition as well as cleaning cycle.

Fermentability Predictor for brewing QC with SIBA

Fermentabiliyt Predictor - Inline RDF/ADF estimation at the mash-tun

Using the Specshell Inline Brewing Analyzer (SIBA), not only can you measure standard parameters such as extract formation and carbohydrate profile without manual sampling processes, but you can now also determine wort fermentability as both unit of apparent and real degrees of fermentability!

The SIBA system will automatically quantify batch-to-batch variation in wort fermentability, preventing labor intensive methods with slow turnarounds. This breakthrough technology now gives brewers the tools to deliver to-spec wort even more easily, improving recipe and mash schedules optimization.

 Equip your brewhouse with the Fermentability Predictor as part of your robust stand-alone real-time process monitoring system SIBA and yield the benefits of lab-free control.


The fermentability of a given batch of wort is a function of grist composition, ingredient quality, brewing configuration (infusion / decoction etc.), mash schedule, and the introduction of endogenous enzymes. Controlling the mashing process to maximize extract formation while controlling fermentability is essential for brewers to guarantee that the wort is produced up to specification.

Yeast mediates the conversion of fermentable sugars (maltotriose, maltose, glucose, fructose, and sucrose) to alcohol, leaving behind the longer maltodextrins and other minor components. Fermentability describes proportion of wort extract that yeast are able to ferment to alcohol, or effectively the percentage of sugars that are convertible to alcohol in a given wort. Several parameters other than wort sugar composition influence a yeast's contribution to fermentability, such as wort free amino acid content, yeast strain and fermentation conditions, but predominantly in most barley based worts, it is the sugars that determine this parameter.

Wort fermentability is measured in the brewing laboratory through forced fermentations of overpitched wort with differing methods described by the American Society of Brewing Chemists and European Brewing Chemists. This process is time consuming, labor intensive, and can be subject to a number of user and systematic errors. However, this value is critical for improving recipes and mash schedules when faced with variable raw material quality – this delay in data generation is subsequently limiting to brewhouse optimization and daily QC, potentially resulting several off-specification batches before issues can be addressed.

The Fermentability Predictor integrated into the SIBA platform now offers brewers inline and automated quantification of the wort fermentability (apparent and real fermentability) at the end of each batch. Inline measurement of wort fermentability prediction allows digitalized QC for daily brewhouse operation and batch-to-batch optimizations to be made while eliminating laboratory workload. Improvements in wort fermentability can be translated into greater product yields, time savings in the brewhouse, or increase in adjunct use.

Fig1. Fermentability Prediction historic data for the several batches of a specific recipe. Recipe upper and lower limits set to recipe requirements by the brewery, showcasing the visual quality control feature of SIBA.

Apparent and Real Fermentability

There are two main ways to consider the degree of fermentability of a wort or beer, 'apparent' and 'real', the main difference being how the final extract is considered with regards to the concentration of ethanol in this sample [1] [2 ] [3].

The Apparent Degree of Fermentation is calculated from the apparent extract after final attenuation (AEFA) and the original extract (OE), and is widely used to compare batches of the same recipe with similar original extracts; however, this parameter should be handled with care when comparing different OEs. AEFA is directly calculated from the density of the product after fermentation and converted to a value in ° Plato using the same scale as before fermentation. This assumes that the starting matrix (binary mixture of carbohydrate and water) pre-fermentation have the same composition as after fermentation; however, the fermented product is a ternary mixture as it contains ethanol. The lower density of the ethanol significantly reduces the measured final extract compared to a comparable mixture of sugars and water.

The alternative is to measure or calculate the Real extract (RE, in ° P), which accounts for the concentration of lower density of ethanol effectively estimating the true quantity of dissolved sugars (and proteins) remaining after fermentation. This can be done using labor intensive laboratory techniques or more typically calculated using the formula of Balling, which when used in combination with a factor accounting for sugar uptake by yeast, then allows calculation of the Real Degree of Fermentability (RDF). This parameter allows comparisons between worts of varying original extracts to be more reliable in terms of fermentation performance.

The SIBA Fermentability Predictor estimates both the ADF and RDF of each batch during mash out, giving brewers the resources to control and optimize their processes easily for increased mash efficiency and time savings!

Conventional laboratory fermentability measurements

To measure the fermentability of a given wort there are several prescribed methods from the European Brewing Chemists (EBC, EBC 9.4) and American Society of Brewing Chemists (ASBC, Wort-5) that outline how to perform this technique. A volume of wort is boiled and fermented with a large pitch of fresh yeast, with the extract measured before and after. However, these and other methods in the scientific literature disagree on the duration of fermentation, the fermentation temperature, agitation, and yeast pitch size. All of these parameters significantly influence the results of this test. Too short a fermentation time and the wort will not be fully attenuated, too long a duration or too warm and you will experience ethanol evaporation leading to higher AE.

Specshell fermentation scientists have examined both EBC and ASBC methods, as well as the impact of several parameters and have established a reliable test bed for determining wort fermentability that neither significantly over-nor under-estimates AE measurements. This highly reproducible method was applied to worts brewed and measured using SIBA on our in-house pilot system, to produce reliable calibration samples applicable to a wide range of OE and fermentabilities.

Fig2. Validation of the multivariate models using independent data set measured in-line using the SIBA

Model performance

Specshell data scientists utilized the in-house produced calibration samples to train multivariate models for prediction of the RDF. The models use advanced processing steps to highlight the key spectral features that contain information about the RDF. The trained models were tested with an independent validation data set consisting of mashes that were conducted and measured in-line using a SIBA instrument in our in-house pilot facility. The validation set contained samples with a wide range of RDF.

Model performance is robust, enabling accurate prediction of wort RDF across the whole validation range, with a very high accuracy (correlation coefficient R 2 = 0.999 and a root mean squared error in validation (RMSEV) = 0.0145 RDF units) and a high precision ( the standard deviation of the residuals was 0.56 RDF units).

Limits of Use

Since the SIBA is measuring inline at the mash-tun, processes that influence fermentability that take place after wort is transferred from this vessel are not captured with the measurement system. This for instance might include the use of thermostable enzymes that are still active during and can increase the proportion of fermentable sugars. Also, the addition of syrups and adjuncts post mashing will likely increase the fermentability of the wort beyond what was predicted by the Fermentability Predictor during mashing. In these cases, the predicted the fermentability value still has significant value as a benchmarking tool to assess mash performance or ingredient contributions between batches.


European Brewing Chemists (EBC) 8.6.1 Fermentability, Attenuation Limit of Wort Reference Fermentation - 2002

European Brewing Chemists (EBC) 9.4 Original, real and apparent extract and original gravity of beer - 2004

American Society of Brewing Chemists (ASBC) Wort-5: Yeast Fermentable Extract

Main contributors

Application Scientist: MsC Jabob Grønberg and Dr Joshua Mayers

Data Scientist: Dr. Pau Cabaneros

This project was run under the Innobooster program by the Innovationfonden, part of the Intelligent Brewing program.

Next Generation Carbohydrate Analysis

Next Generation Carbohydrate Analysis

In the current Horizon2020 SME project, Specshell is developing new robust inline analyzers for the ethanol and starch industries; where part of our Chemistry team, Joshua Mayers, Katrin Pontius and Pernille Christensen, is pushing the existing technological and scientific limits of carbohydrate analysis. With the development of a new quantitative method combining HPAEC (High Performance Anion Exchange Chromatography) and HPLC with high field 2D-NMR, Specshell is now able to accurately characterize complex carbohydrate matrices from starch-based industries

In the Horizon2020 project the Specshell team has discovered several limitations and shortcomings in the industry's analytical methods for characterizing the complex fermentation slurries. Today the industry largely relies on HPLC protocols which are inherently poor for characterizing and quantifying dextrins, which leaves large parts of the hydrolyzate sample matrix poorly characterized. As chemometric models can never be better than the analytical reference methods they rely on, the efforts in analytical reference methods are a key element in Specshell's mission to become the new standard must-have equipment in every bioethanol plant and starch based industries.

Intelligent brewing

Intelligent brewing

Specshell ready to give a boost to breweries worldwide through intelligent brewing.

Even though in quarantine, our CEO Erik Hoffmann and CTO Andreas Jonas Kunov-Kruse were excited to celebrate that the Intelligent Brewing project has been approved under the Innovationsfonden program. This will support Specshell with a grant to develop new software technologies to fully automate the data analysis and integration of SIBA with the brewhouse. The project will ensure a continuous recipe and process optimization in the brewhouse, directly responding to the needs from current and future clients in the brewing world.





Specshell is now (remotely) working towards the next self-driving brewhouse technology, making the way from digitalized to intelligent breweries. Let’s all keep working, but in a social distancing manner for the moment.

Specshell contributing to the Spanish beer

Specshell contributing to the increasing Spanish beer market

Spain has shown itself to be a beer drinking country in 2018 after surpassing 40 MhL of beer consumed, becoming the third largest beer consuming country in Europe based on the Socioeconomic Report of Brewers of Spain.

Spanish brewers worked hard to meet consumer needs by increasing production by 2.2% compared to the previous year, brewing a record breaking 38.41 MhL.

To ensure the foreseen 2020 demand, a top performing Spanish brewery has now been equipped with SIBA. Based on the live inline mashing data analyzed by SIBA, the brewers can now improve the annual productivity by reducing the main brand’s mashing time with data certainty.

The mashing digitalization with SIBA will allow the brewery to fulfill the 2020 production goals without any major brewhouse changes.

5 years of Specshell

5 years of Specshell

Enthusiastic and thrilled, 5 years ago a very special team got together to found Spechsell ApS.

Today the four founders are happy to look back on the major steps that has made it possible for Specshell to be the exciting and fun company to be working at, that it is today:

2014 – Financing: MMF, Otto Bruun, Alex Foss Industrifond.

2016 – International Development: Specshell Inline Brewing Analyzer (SIBA) technology developed and tested in several international industrial breweries to optimize and quality control their production process.

2017 – Production: Expansion of operations and facilities to begin producing SIBA units.

2018 – Commercialization: SIBA technology permanently installed at several large international breweries.

2019 – Novel Developments: Horizon 2020 funding will make it possible to further develop the technology towards fermentation and bioethanol processes.

Congratulations and thanks to everyone making it possible for this to happen!