The global alcoholic beverage market has a projected value of $1.684 trillion in 2025. Beer is the most widely consumed alcoholic beverage, accounting for 78.2% of total consumption worldwide.
One reason for beer prevalence in the market is its suitability for large-scale production. A wide range of products are offered that differ in appearance (color, clarity, and foam), flavor, and taste. In recent years, the market for and consumption of craft beers manufactured by microbreweries have grown.
Microbreweries market their products based on unique recipes, high quality, and product distinction from both large-scale beer manufacturers and other microbreweries. Despite an expansion in the scope of products, the four raw materials needed for beer production remain the same: barley, water, hops, and yeast.
Image Credit: Galaxy Scientific Inc.
Beer manufacturing is a multi-step process that requires quality control testing at every step of the process to ensure that the final product meets specifications.
The quality of raw materials has a considerable effect on the final product. Before the brewing process begins, the characterization of barley, yeast and hops can assist the brewer in improving the process. Malting is the process of making malt by roasting, mashing, and germination of barley. The finished product of malting is mash, a mixture of crushed grains and hot water. During the mashing stage, starches are broken down with the assistance of enzymes into fermentable sugars. The soluble materials in mash are a sweet, fermentable liquid called wort, which is separated from the grains, cooled, and added to the fermenter with yeast for fermentation.
Beer fermentation is the process of converting wort, water, and hops into an alcoholic beverage. The yeast breaks down the fermentable sugars in the wort, releasing carbon dioxide, ethyl alcohol, and other compounds that create the flavor, color, and aroma of the beer.
After fermentation is completed and the beer is put into the final holding container, final quality testing can check to make sure the beer meets product specifications. In addition to pH, alcohol content, original gravity, carbonation level, and other standard parameters, final tests can include sensory analysis (aroma, taste, color) and tests for undesirable chemicals and microorganisms.
Process control feedback during brewing, particularly during the fermentation and malting stages, is crucial for brewing high-quality beer. Real-time feedback on moisture and nitrogen in barley, germination parameters, sugars during mashing, and alcohol and original gravity during fermentation help the brewer improve the process and optimize resources for brewing.
Traditional testing methods for quality control parameters in beer are expensive, time-consuming, labor-intensive, and often ill-suited for real-time testing during manufacturing. They can require extensive sample preparation, the use of toxic chemicals or solvents, and can measure only one chemical or physical parameter of interest in a single test. There is a need for fast and cost-effective methods for real-time monitoring at all stages of the brewing process. NIR spectroscopy offers the advantages of being fast and non-invasive while requiring little or no sample preparation. Once calibration models are created that correlate parameters of interest to the NIR spectra, multiple parameters can be determined from a single measurement.
In the sections below, a discussion and review of the use of NIR spectroscopy during each stage of beer manufacturing is presented. Scientific studies are examined that have proved the feasibility of using NIR spectroscopy as an alternative to traditional quality control methods.
Raw Material Testing
Barley
Analytes:
Moisture, Starch, Protein, Total Nitrogen Content, Hardness, β-Glucan, Genotype Classification, Mycotoxins
Principal quality parameters for barley include moisture, protein, starch, and nitrogen, which is indicative of protein content. Higher protein barley can have negative effects such as higher malting loss, lower foam retention, and excessive haze in the final product. High moisture barley can lose its ability to germinate properly and is at risk for mold and fungal contamination. The Analysis Committee of the European Brewery Convention has recommended the use of NIR spectroscopy for determining moisture and nitrogen in barley.
Other quality parameters have been studied using NIR spectroscopy as an analytical method, such as hardness and β-Glucan. β-Glucan in barley can be directly correlated to extract yield, wort viscosity, and malt quality. Genotype classification has been studied as well, which can have a strong effect during germination and malt production.
Some work has been done on mycotoxin contamination with promising results. However, the correlation between the NIR spectra and mycotoxin contamination is indirect as the mycotoxin concentration is far below the threshold of detection for NIR spectroscopy. Such indirect correlations can be feasible but extensive validation work is required to ensure that the correlation is reliable, as it is almost certain that the parameter being measured is not the correlated model parameter, but rather a parameter that has a direct effect on the parameter of interest.
Image Credit: Galaxy Scientific Inc.
Hops
Analytes:
α-Acids, β-Acids, Hop Storage Index (HSI)
NIR spectroscopy has been studied as an alternative to traditional testing methods in hops analysis. Acid compounds in hops are precursors to bittering agents and are normally determined using HPLC.
HSI is the estimated alpha acid potential loss when hops are stored at room temperature for six months. UV wavelength absorptions at 325 nm (hops acids) and around 275 nm (degenerative compounds associated with oxidation) is the standard method for measuring HSI. Results for both acid compounds and HSI in applications studies have proved the feasibility of using NIR spectroscopy to measure these parameters in dried hops.
Image Credit: Galaxy Scientific Inc.
Yeast
Analytes:
Glycogen, Trehalose (Dried & Slurry), Protein
Glycogen and trehalose are major storage carbohydrates in yeast. Protein in yeast is a major physiological parameter and is used to determine the price of spent brewery yeast by-product. Studies have shown all parameters can be determined using NIR spectroscopy. In the case of trehalose, a comparison was made between using dried yeast and slurry yeast. Results were much better using slurry, which would be the preferred measurement in an on-line process setting.
Image Credit: Galaxy Scientific Inc.
Malting
Analytes:
Moisture, Extract, Nitrogen, Starch
The malting process begins with steeping. Sorted and cleaned barley is transferred into tanks and covered with water. During germination, barley undergoes a complex series of biochemical reactions to create malt. Monitoring moisture is important during this process. Steeping is complete when moisture is high enough to allow uniform breakdown of starches and protein. The moisture level in the barley increases from an initial level of 14% to 15% to around 42% to 44% at the end of germination, with the germination process starting at around 30% moisture.
Work has been conducted on monitoring malt quality during germination by measuring starch and nitrogen (an indirect measurement of protein) using NIR spectroscopy. Real-time feedback during germination allows brewers to accelerate or decelerate the process by adjusting temperature and humidity. Finished malt should have a moisture limit of 5% or less, which is important because the moisture is used to calculate dry matter. Dry matter is used by brewers as a yardstick for all other quality parameters.
Image Credit: Galaxy Scientific Inc.
Mashing
Analytes:
Moisture, Total Carbohydrates, Fermentable Sugars, Nitrogen, Hot Water Extract, Protein
After malting, the malt is ground through the mill and the brewing process begins with mashing. The main objective of mashing is to form maltose and other fermentable sugars from solubilized starch by adding hot water. Once the starch is broken down into sugars, the sugars are extracted into a sweet liquid called wort which is used for fermentation. The water temperature is carefully controlled during the mashing process as it can greatly affect the flavor, color, body, and sweetness of the final beer.
The water temperature during mashing is usually between 155°F and 175°F and can involve pauses during the process. Studies using NIR spectroscopy to monitor mashing parameters have been successful, although most studies used filtered wort in transmission mode. Mashing matter is thick enough to make real-time monitoring difficult, but advances in hardware have made the prospect of real-time analysis during the mashing process more feasible. Such analysis would be tremendously beneficial to brewers as it would enable optimal temperature adjustment during the mashing process.
Image Credit: Galaxy Scientific Inc.
Fermentation
Analytes:
Alcohol, Original Extract, Real Extract, Biomass, Soluble Solids Content (Brix), pH
Fermentation is the process of converting wort into beer. Yeast breaks down the sugars in the wort to create alcohol, carbon dioxide, and other compounds that give beer its aroma and flavor. Yeast affects the taste, color, and alcohol content. Fermentation time and the temperature of the tank vary depending on the type of beer being made. It is often a three- stage process: primary, secondary, and conditioning (lagering).
Optimization of fermentation is a complex process because many factors can affect the final alcohol content and overall yield. HPLC is often the method of choice for fermentation monitoring and while effective, there are many drawbacks to it. In particular, it is ill-suited for real-time monitoring.
Numerous studies have proven that NIR spectroscopy is a valid method for the optimization of beer fermentation. Alcohol monitoring as well as real extract and original extract have worked so well that NIR spectroscopy is an approved method by the Analysis Committee of the European Brewery Convention. Soluble Solids Content (SSC), pH, and Biomass are parameters that can also be monitored.
The potential of fermentation optimization using real-time feedback from NIR spectroscopy cannot be understated. Protocols can be optimized such as changing enzymes, process parameters, and nutritional supplements, resulting in the optimization of both yield and fermentation time. Benefits include considerable savings in raw materials, processing fuel, labor, maintenance, and equipment, potentially saving large breweries millions of dollars per year.
Image Credit: Galaxy Scientific Inc.
Final Quality Analysis
NIR spectroscopy can be used for a final quality check to make sure the beer means product specifications. Alcohol content, pH, SSC, original gravity, carbonation level, foam volume, and other standard parameters are all measurable from a single NIR spectrum scan and calibration models.
Work has also been conducted to test for undesirable chemicals and microorganisms. Final quality tests can be subjective for sensory analysis parameters such as color, aroma, and taste. Studies have been conducted to correlate the NIR spectra with these final sensory parameters and have demonstrated the potential to help remove the subjectivity from such testing.
Image Credit: OlegSam/Shutterstock.com
Process Analytical Technology (PAT)
Process Analytical Technology (PAT) was first introduced by the FDA for the pharmaceutical industry but has proven to be effective as a modeling and control strategy for the food industry. Many steps of the beer manufacturing process benefit from using the principles of PAT to ensure quality.
Inherent advantages of implementing PAT into brewing include controlled and optimized utilization of raw materials, reduction in variation of the final product, waste reduction, minimization of process cycle time, and the replacement of slow, costly, and ineffective laboratory testing methods with newer and more reliable sensor technologies, such as NIR spectroscopy.
On-line Analysis
While the feasibility of measuring beer quality control parameters has been proved in both academic studies and real industrial applications, there are inherent challenges to using NIR spectroscopy as an on-line process control tool. Off-line analysis is easily attainable but does require the transfer of a sample to the instrument. While still much faster and more effective than traditional methods, laboratory instruments are not suitable for real-time analysis
At-line analysis involves the placement of an instrument in a manufacturing environment and using a sampling system to pull a sample from the process to the instrument. Such methods are also effective but still do not provide real-time feedback and analysis to show both changes in sample parameters and differences in the homogeneity of samples in a process if an undesirable change occurs during the process.
On-line analysis involves a sensor being placed either into or above the manufacturing process to provide real-time feedback for the parameters of interest. The nature of and changing physical characteristics of the physical components of beer manufacturing can make the hardware needed for monitoring very challenging.
For example, mashing creates a mixture that is difficult to use transmission (light passes through the material to obtain NIR spectra) for because the light must pass through it to reach the detector sensor. It is also difficult to use reflectance (light reflects off the material to obtain NIR spectra) as the liquid in the mash absorbs a large amount of the light, minimizing the light reflection to the detector sensor.
Advances in hardware, fiber optics, transflectance probes, diffuse reflectance mechanisms, and cleaning mechanisms have greatly contributed to the potential for using NIR spectroscopy as a real-time process control and monitoring tool. Software advances and the use of cloud-based systems have also contributed to the use of NIR spectroscopy as a tool for manufacturing monitoring.
Galaxy Scientific's QuasIR™ 2000 Near Infrared Spectrometer. Image Credit: Galaxy Scientific Inc.
Recent Advances
Recent work on the use of NIR spectroscopy in beer analysis has not only focused on new applications, but also the use of it with other analytical technology and methods. Calibration model and method development to correlate the NIR spectra to chemical and physical parameters of interest can also be a challenge and recent analysis has worked on ways to simplify this process.
Some recent work focused on using NIR spectroscopy in combination with a robotic analyzer in one study and an electronic nose sensor in the other. A parameter known as MaxVol (Maximum Volume of Foam) was easily correlated to the NIR spectra after reference values were obtained from the robotic analyzer. The analyzer can measure multiple color and foam parameters and could be used in combination with a NIR spectrometer for quality control analysis.
The nose sensor study was used to identify numerous off-aromas/flavors in beer samples and determine the feasibility of using NIR spectroscopy to identify beer that is faulty. The study proposed an integrated AI system for smart detection of beer faults using NIR spectroscopy, the electronic nose, and advanced machine learning modeling algorithms. Results were excellent and proved the feasibility of this analytical system, which could be of great benefit to both craft and large-scale brewers.
There have been advancements in the use of chemometric modeling algorithms for the monitoring of manufactured products using NIR spectroscopy as well as the use of in-line probes. A recent study showed excellent results using an in-line transflectance probe during mashing for the measurement of Free-Amino Nitrogen (FAN), an important parameter in wort for the growth of yeast cells and desirable fermentation. Advances in both hardware and machine-learning algorithms have enabled the extraction of relevant spectral information for chemometric modeling. This means that older technology could not collect meaningful spectra for analysis nor were past modeling algorithms powerful enough to create accurate and robust models. Coupled together, these two advances have demonstrated great potential when used in tandem for real-time monitoring and process control of beer manufacturing.
In some cases, especially for smaller craft brewers, a more simplistic approach for beer analysis using NIR spectroscopy is beneficial. A recent study examined a comprehensive approach to monitoring an entire beer manufacturing process using NIR spectroscopy and a multi-variate control chart to monitor beer development. The goal was to demonstrate that variations between each step were negligible compared to the variation of the whole process, ultimately allowing for the creation of a general model that could be used to monitor the entire process by measuring the Soluble Solids Content (SSC). The results showed that the variability between batches was smaller than the variability between the manufacturing process steps. Ultimately, the monitoring of a single parameter (in this case, SSC) using NIR spectroscopy showed the multivariate analysis was versatile, simple, and reliable enough to monitor and control the entire beer manufacturing process at all steps.
Galaxy Scientific
Galaxy Scientific is an industry pioneer in the use of optical Near Infrared Spectroscopy. Our QuasIR™ family of NIR spectrometers uses Fourier Transform Near-Infrared (FT-NIR) technology for laboratory, field, and process applications. Our passion is innovation and our mission is to develop uniquely robust NIR instruments to solve critical analytical problems in numerous sectors, including beer manufacturing.
For more information about Galaxy Scientific and to contact one of our applications specialists, please visit our website at Galaxy Scientific Inc.
For more detailed discussion on the topics covered in this article, including advanced statistics, overview of the beer manufacturing process, and a review of applications studies for beer analysis using NIR spectroscopy, please visit the following sections on the Galaxy Scientific NIR spectroscopy for food analysis website:
Alcoholic Beverages - NIR-For-Food
Beer Overview - NIR-For-Food
Beer Analysis - NIR-For-Food
References
- Process Analytical Technology for the Food Industry -O’Donnell, Fagan, Cullen, et al., Springer, Food Engineering Series (2014)
This information has been sourced, reviewed and adapted from materials provided by Galaxy Scientific Inc.
For more information on this source, please visit Galaxy Scientific Inc.