Flavor Stability Of Beer Research Articles

Husk Separation (Kubessa Method) Impacts the Aging Chemistry of Beer.

The removal of husks before the mashing process, also known as the Kubessa method, is an established brewing practice often positively associated with smoothness and better flavor-stability of beer. Empirical evidence on the effect of the Kubessa method on beer, however, has been lacking. Similarly, our study's comprehensive analysis of established brewing attributes revealed that traditional methods do not fully capture the impact of husk separation in beer brewing. Conclusive evidence of the Kubessa method's impact on beer aging chemistry was obtained through ultrahigh resolution mass spectrometry (FT-ICR-MS), revealing intricate molecular details inaccessible to conventional analytical techniques. The compositional information on thousands of molecules in Kubessa beer was resolved and compared to whole malt mashing. Machine learning algorithms applied to aging experiments identified over 500 aging-related compounds inhibited by husk separation. Complementary Time of flight mass spectrometry (ToF-MS) coupled with chromatography further confirmed that the mashing of husks introduces sulfur-containing lipid compounds. These significant differences in the beer composition provide valuable insights for further investigation into the staling protective effect of husk-separation (Kubessa process) during beer production, as empirically demonstrated in this work.

A Preliminary Study on the Effect of Adding Sugarcane Syrup on the Flavor of Barley Lager Fermentation.

This study focuses on the diversified utilization of the sugarcane industry, and sugarcane syrup, as a by-product of the sugarcane industry, is a good raw material for fermentation. Bringing sugarcane syrup into beer is conducive to the enrichment of the sugar industry, and it can improve the flavor of beer and make it more aromatic. This study determined the optimal fermentation process for beer. By analyzing the consumption rate of the carbon and nitrogen sources of raw materials, the nutrient utilization of yeast, and the causes of differences in flavor substances, the flavor composition and flavor stability of beer were determined by SPME-HS-GC-MS technology. The results showed that beer brewed with sugarcane syrup as an auxiliary raw material met the basic specifications of beer. The addition of sugarcane syrup to the wort base increased the utilization of amino acids by the yeast, and LS (lager with added cane syrup) increased the nine flavor compounds of the beer, which constituted the basic flavor of the beer, bringing new flavor compounds compared with the normal all-barley beer. Forced aging experiments showed that LS produced fewer aging compounds than OWBL. Various experiments have shown that it is feasible to ferment beer with sugarcane syrup instead of partial wort.

Differences in structure, stability and antioxidant activity of melanoidins from lager and ale beers

Beer melanoidins, the final products of the Maillard reaction (MR), play a critical role in determining the flavor stability of beer due to their antioxidant properties. This study investigated the structure, stability, and antioxidant activity of lager beer melanoidins (LBM) and ale beer melanoidins (ABM). The results revealed that ABM possessed a higher browning index and molecular weight, attribute to its relatively intense MR. However, this intensity also led to a more unfolded and disordered structure in ABM. Conversely, LBM outperformed ABM in the FAST index, thermal stability, and total antioxidant activity because the low alcohol content in lager beer reduced oxidation and thermal degradation while boosting the stability and antioxidant activity of melanoidins. As a result, it would offer a novel possibility to improve beer flavor stability by optimizing the brewing process to modify the structural and functional characteristics of melanoidins.

The impact of lager brewing yeasts on flavor stability of pilot-scale beer during storage

AbstractThe aim of the present study was to investigate the impact of two lager brewing yeasts (KVL001 and KVL018), known to produce different levels of sulfite and thioredoxin, on the flavor stability of beer during storage for 24 weeks at 25 °C and 35 °C. Fermentations with the two yeast strains were carried out in two identical pilot scale brews and provided fresh beers with very similar sensory profiles, only differing significantly in content of sulfite, iron, thioredoxin, and free amino acids. No difference in protein thiols was observed indicating that thioredoxin was not active in the final beer. The yeast strain KVL018 consumed less free amino acids than KVL001 resulting in fresh beers with a higher content of free amino acids. During storage, the beers developed very similarly, but the beers fermented with KVL018 developed more 'fruity aged/vinous' flavor, especially at 35 °C. This suggested that a higher degree of the Maillard reaction took place in these beers due to the higher content of free amino acids. Beers fermented with KVL018 also contained more sulfite and less iron, but scored lower in the general evaluation of the sensory analysis. In conclusion, our results indicate that the yeast strain (KVL001) taking up more free amino acids resulted in more flavor-stable beer due to a lower degree of the Maillard reaction, while no clear effects were observed on oxidation.

Formation of staling aldehydes in different grain bed layers in an industrial scale maltings

Understanding the contribution of raw materials to the quality of the final product is crucial for the food industry. In the brewing process, malt delivers various compounds that compromise the flavour stability of beer, including staling aldehydes and their precursors. The primary aim of this study was to investigate the evolution of staling aldehydes and their cysteinylated counterparts throughout industrial scale pale malt production. The second objective was to study the extent to which process related gradients (e.g., temperature, moisture) may contribute to the differential formation of free and bound state aldehydes. Samples were collected from two industrial scale, pale lager malt production processes as a function of process time (germination, kilning, and cooling) and the position of the kernals in the grain bed (bottom, middle and top layers) during kilning. The levels of free and cysteinylated aldehydes were determined. The results show that the initial stage of germination is accompanied by enzymatic fatty acid oxidation as reflected by the formation of hexanal and trans-2-nonenal. Drying at elevated temperature (at a critical moisture content of 6-9%) results in the intensified formation of cysteinylated Strecker aldehydes and furfural. Moreover, a rapid increase in the formation of (cysteinylated) Strecker aldehydes furfural and trans-2-nonenal continued through kilning. A clear effect of temperature and moisture gradients was observed on the formation of aldehydes and it is concluded that exposure to heat load plays a critical role in the development of cysteinylated aldehydes during malt production. This publication is dedicated to the memory of Professor Luc De Cooman.

Enhancement of dimethyl sulphide separation during wort boiling by a single spinning cone evaporator

Wort boiling is the most energy intensive stage in the brewing process. Novel wort boiling systems have been explored to reduce primary energy consumption and improve wort quality and beer flavor stability. Low thermal stress boiling is proposed for wort boiling, but the content of dimethyl sulphide (DMS) in the wort may exceed the required product threshold. A single spinning cone evaporator (SCE) is proposed to enhance the separation of DMS and minimise the energy consumption for wortboiling. The performance of a SCE was evaluated by measurement of fluid flow, ratio of DMS removal, wort self-evaporation ratio based on sensible heat, and thermal efficiency. The results show that use of a spinning cone evaporator, reduced DMS by up to 90% with 2.1% wort self evaporation ratio with less primary heat consumption. The SCE operation exceeds the evaporation of a gravity film cone. Under reduced pressure, the spinning cone evaporator was less effective in DMS removal.

Assessment of the Prediction Power of Forced Ageing Methodology on Lager Beer Aldehyde Evolution during Maritime Transportation.

The globalisation of the beer market forces brewers to have methodologies that rapidly evaluate the evolution of beer flavour stability. Commonly used forced ageing methods have limitations since temperature and transportation conditions (temperature, vibrations, long-distance travel, and other factors) impact beer quality. This study assessed the prediction power of a forced ageing methodology on the evolution of aldehydes during maritime transportation across four sample groups (maritime transport, storage simulation, and three ageing periods: 7, 21, and 28 days at 37 °C), which differed in their bottle-opening system (either crown cap or ring pull cap). The results revealed that forced ageing up to 28 days could estimate the evolution of phenylacetaldehyde, 3-methylbutanal, 2-methylpropanal, and hexanal during maritime transport. In contrast, the benzaldehyde content was consistently underestimated, on average, 0.8 times lower. In general, the ageing conditions significantly favoured the formation or liberation from a bound state, up to 2.2 times higher, of trans-2-nonenal, acetaldehyde, and 5-hydroximethylfurfural in comparison to the levels registered on exportation simulation beers. Moreover, forced-aged beers with ring pull caps developed quantifiable levels of nonanal and increased phenylacetaldehyde, benzaldehyde, and acetaldehyde content over time. Moreover, thermal stress induced a continuous increase in the extent of beer staling, up to seven times higher, in most samples.

Flavour Stability of a Cold-Stored Unpasteurized Low-Alcohol Beer Produced by Saccharomycodes ludwigii

Low-alcohol beer (LAB) is a growing part of the brewing industry in terms of market volumes and consumer interest. Universities and research centres are making efforts to improve organoleptic profile and flavour stability of the product. One of the main limitations of such products is the stability. These beers must be severely filtered and pasteurized, causing a significant loss of quality in terms of flavour. Herein, flavour stability of an unpasteurized and unfiltered LAB was checked during 120 days of cold storage (4 ± 1 °C). The results showed that the beer remained stable for 120 days for many observed parameters. The alcohol content increased from 0.5 to 0.7% v/v. The beer without oxygen was more stable than that filled with oxygen in the headspace. The results confirmed the possibility to produce an unpasteurized craft LAB by Saccharomycodes ludwigii by the cold chain.Graphical

The Effect of Mash-In Temperature on the Characteristics and Flavor Stability of Pilsner-Type Beer

Beers were brewed at mash-in temperatures of 35 °C, 50 °C, and 65 °C, and their flavor profiles and stability were examined. Beers with mash-ins at 35 °C and 50 °C exhibited full-bodied taste and estery sensory qualities with higher concentrations of esters and amino acids. Higher extract yields were obtained in wort with mash-ins at 35 °C and 50 °C, the optimal temperatures for enzymes to break down the tissue where starch granules are located. In contrast, the beer with a 65 °C mash-in temperature had a light taste and a toast-like aroma. In terms of providing nutrition for the yeast, the proteolytic process to produce amino acids seemed unnecessary for brewing beer made exclusively from malt. Following a month of storage at 30 °C, cardboard flavors predominated in beers with mash-in temperatures of 35 °C and 50 °C, while honey and sherry-like scents predominated in beers with a mash-in temperature of 65 °C. The concentrations of the 14 components contributing to the stale flavor of Pilsner-type beers, including Strecker aldehydes, did not correlate with mash-in temperature, with the exception of the concentration of (E)-2-nonenal, even though the mash-in temperatures were predicted to affect the formation of Strecker aldehydes during beer storage.

Evaluation of the antioxidant characteristics of craft beer with green tea

The addition of green tea as antioxidants to beer can improve the beer's flavor stability by protecting against staling during storage. To analyze the effect of different green teas on the flavor stability of beer, we developed an approach to rapidly evaluate their antioxidant activity. Ten types of craft beer were produced by adding different kinds of green tea during brewing, and their antioxidant activity and phenolic profiles were evaluated. The results showed remarkable variations in antioxidant activity and antioxidative compound contents, which were considerably higher in green tea beers than in non-tea beer (p<0.05). A comprehensive evaluation function was developed to evaluate the total antioxidant activity of beers using principal component analysis. The highest total antioxidant activity was observed in Taiping Houkui beer, with a comprehensive evaluation score of 2.53. Pearson correlation analysis suggested that (-)-epigallocatechin gallate, (-)-epicatechin gallate, and (-)-epigallocatechin were strongly correlated with the total antioxidant activity of green tea beers (p<0.01). The summation of their contents represented more than 60% of the total phenolic content of the teas, which can be used to predict the total antioxidant activity of green tea beers. PRACTICAL APPLICATION: Flavor stability is of prime concern for brewers, and flavor aging is increasingly becoming the limiting factor in beer shelf life. The application of green tea as antioxidants in beer can improve the flavor stability by protecting against beer staling during storage. The analytical method developed in this study will contribute to the rapid comparison of the effect of different green teas on the flavor stability of beer. Furthermore, the research findings demonstrate the potential benefits of green teas to beer flavor stability, which is of considerable importance in promoting the development and consumption of green teas.

Novel Saccharomyces cerevisiae variants slow down the accumulation of staling aldehydes and improve beer shelf-life

Beer quality generally diminishes over time as staling compounds accumulate through various oxidation reactions. Here, we show that refermentation, a traditional practice where Saccharomyces cerevisiae cells are added to beer prior to bottling, diminishes the accumulation of staling aldehydes. However, commonly used beer yeasts only show a limited lifespan in beer. Using high-throughput screening and breeding, we were able to generate novel S. cerevisiae hybrids that survive for over a year in beer. Extensive chemical and sensory analyses of the two most promising hybrids showed that they slow down the accumulation of staling aldehydes, such as furfural and trans-2-nonenal and significantly increased beer flavor stability for up to 12 months. Moreover, the strains did not change the original flavor of the beer, highlighting their potential to be integrated in existing products. Together, these results demonstrate the ability to breed novel microbes that function as natural and sustainable anti-oxidative food preservatives.

The Impact of Whirlpool Hop Addition on the Wort Metal Ion Composition and on the Flavor Stability of American Style Pale Ales Using Citra® Hop Extract and Pellets

The characteristic hoppy flavor of pale ales is known to be unstable and deteriorates during the beer’s shelf life. Metal ions, in particular iron and copper, have a prooxidative effect and therefore accelerate beer flavor deterioration. Recent studies suggest that hop constituents may complex metal ions in beer thereby suppressing their negative effect on beer flavor stability. Using benchtop wort boiling experiments and quantitating metal ions in the cast wort, this study determined that different whirlpool additions of up to 3.0 g/L hop extract or up to 17.4 g/L pellets significantly reduced metal ion concentrations in wort, especially Fe, which was reduced by a factor of up to 6 compared to the control. Based on identified dose- and product-related effects, 2.5-hL brewing trials were performed using a selection of whirlpool hopping levels with either extract or pellets revealing significant differences in resinous and sweaty flavor. The flavor of the beer hopped with 5.8 g/L pellets was perceived as 8 times more resinous and 9 times sweatier than the control revealing clear differences between extract and pellets, especially at the lower hopping levels. The beer flavor stability was predicted using ESR spectroscopy and verified by performing forced aging experiments at 30 °C and monitoring beer flavor changes by sensory evaluation. Results indicate that both extract and pellet whirlpool hopping improve beer flavor stability by reducing the formation of age-related off-flavors and by supporting the retention of flavors related to freshness with only minor variations between the two hop products.

Assessment of Staling Aldehydes in Lager Beer under Maritime Transport and Storage Conditions.

Beer flavor stability is greatly influenced by external temperature, vibrations, and longer delivery times. The present study assessed the impact of transport and storage conditions on staling aldehyde evolution in lager beers across five sample groups (fresh, transport, and storage simulation, and their controls), which differed in their bottle opening system (either crown cap or ring pull cap). Maritime transport conditions (45 days of travel, vibrations of 1.7 Hz, and warm temperatures (21–30 °C)) were simulated, together with storage time in a distributor’s warehouse (up to 75 days). The results revealed that the concentration of Strecker aldehydes increased more quickly after transport and storage simulation in beer bottles with the ring pull cap opening system, and the contents of 2-methylpropanal and 3-methylbutanal, in particular, were up to three times higher. Benzaldehyde content also increased significantly, by 33% on average, in these samples. Hexanal was only found in beers with a ring pull cap that underwent transport simulation. Further storage after transport simulation significantly reduced the content of 2-methylpropanal, 3-methylbutanal, and hexanal, by 73%, 57%, and 43%, respectively, suggesting the formation of a bound state. 5-hydroxymethylfurfural was continuously increased by 78.5% and 40.5% after the Transport and Transport & Storage simulations, respectively. Transport conditions lead to a slight increase, of 0.6 EBC units, in beer color.

Barley to Beer Flavor Stability Secrets Revealed Using Electron Paramagnetic Resonance EPR Technology​

Barley to Beer Flavor Stability Secrets Revealed Using Electron Paramagnetic Resonance EPR Technology​

A Novel Approach to Develop Lager Yeast with Higher NADH Availability to Improve the Flavor Stability of Industrial Beer.

Flavor stability is important for beer quality and extensive efforts have been undertaken to improve this. In our previous work, we proved a concept whereby metabolic engineering lager yeast with increased cellular nicotinamide adenine dinucleotide hydride (NADH) availability could enhance the flavor stability of beer. However, the method for breeding non-genetically modified strains with higher NADH levels remains unsolved. In the current study, we reported a novel approach to develop such strains based on atmospheric and room temperature plasma (ARTP) mutagenesis coupled with 2,4-dinitrophenol (DNP) selection. As a result, we obtained a serial of strains with higher NADH levels as well as improved flavor stability. For screening an optimal strain with industrial application potential, we examined the other fermentation characteristics of the mutants and ultimately obtained the optimal strain, YDR-63. The overall fermentation performance of the strain YDR-63 in pilot-scale fermentation was similar to that of the parental strain YJ-002, but the acetaldehyde production was decreased by 53.7% and the resistance staling value of beer was improved by 99.8%. The forced beer aging assay further demonstrated that the favor stability was indeed improved as the contents of 5-hydroxymethylfurfural in YDR-63 was less than that in YJ-002 and the sensory notes of staling was weaker in YDR-63. We also employed this novel approach to another industrial strain, M14, and succeeded in improving its flavor stability. All the findings demonstrated the efficiency and versatility of this new approach in developing strains with improved flavor stability for the beer industry.

Development and Validation of a HS-SPME-GC-SIM-MS Multi-Method Targeting Hop-Derived Esters in Beer

Hop-derived esters contribute to beer flavor and changes in the ester spectrum are believed to be an important driver in the flavor–instability of hoppy beers. To date, there exists no published method that enables reliable quantification of hop-derived esters in beer. As the availability of such a method is vital to enlarge the understanding of beer flavor stability, the current article is concerned with the development, validation, and application of a headspace solid phase microextraction gas chromatography selected ion monitoring mass spectrometry (HS-SPME-GC-SIM-MS) based methodology for quantification of 16 hop-derived esters in beer. The validation data shows that choosing suitable HS-SPME-GC-SIM-MS conditions enabled reliable quantification of esters across a range of 1–200 µg/L, with calculated limits of quantification being well below 1 µg/L. Spiking experiments using terpenes and terpenoids evidenced method robustness, most importantly when two commercially available stable isotope labeled internal standards (d6-geranyl acetate and 13C-methyl octanoate) were used. Application to beer samples indicated that beers brewed with different qualities/quantities of hops and differing in freshness could be well differentiated by HS-SPME-GC-SIM-MS analysis of their ester profile. Supplemental data for this article is available online at at https://doi.org/10.1080/03610470.2021.1994814 .

Impacts of Adjunct Incorporation on Flavor Stability Metrics at Early Stages of Beer Production

The fresh flavor of a beer brand is one of its most important quality parameters and should be retained as long as possible through shelf-life. Early stages of beer production can have significant impacts on beer flavor stability. The use of cereal adjuncts – either malted or unmalted – is now widespread practice in brewing. This laboratory mashing study investigated the impacts of incorporating common solid adjuncts (corn and rice) at increasing grist percentages (0-50%) on flavor stability indicators measured in wort. Sweet worts were analysed for metal ion levels (ICP-MS), thiol content (RP-HPLC), oxidative stability (EPR spectroscopy), staling aldehydes (HS-SPME-GC-MS), trihydroxy fatty acids (GC-FID), t-2-nonenal potential (GC-MS), color and thiobarbituric acid (TBI). Mashing conditions for each formulation were adjusted in order to achieve target FAN values. Unmalted rice or corn adjuncts significantly reduced the total metal ion content, color, TBI and staling aldehydes in sweet worts at 50% adjunct incorporation (p < 0.05), relative in each case to the respective all-malt control mash. Our findings showed that unmalted rice or corn adjunct incorporation generally improved flavor stability metrics in sweet worts when similar mashing conditions were applied, whilst increasing the length of the ‘protein stand’ in mashing to reach target FAN in general had a negative impact on flavor stability indicators – e.g., wort T150 values significantly decreased in each recipe at 25% and 35% adjunct relative to the 12.5% adjunct brew but increased again at 50% adjunct, presumably due to the prolonged proteolytic stand employed to achieve target FAN content.

METALS AND POLYCYCLIC AROMATIC HYDROCARBONS (PAHs) IN BEER: A REVIEW

The major cations in beer are potassium, sodium, magnesium, and calcium with the anions, chloride, sulphate, nitrate and phosphate. The minor ones include iron, copper, zinc, manganese, lead, arsenic and phosphorous. These metals are important in beer fermentation because they supply the appropriate environment for yeast growth and influence yeast metabolism. Copper and iron are involved in beer conditioning and ageing through reactions resulting in the formation of reactive oxygen species which readily oxidize organic compounds present in beer, changing the quality of foaming and flavour stability of beer. Small amounts of nitrogen-containing constituents are present and phosphorous is associated with some of these. Only trace amounts of sulphur-containing compounds are present but some of these are very potent flavouring agents. Beer is also subject to PAHs contamination due to the drying and roasting of barley. PAHs have been detected in different types of beverages such as tea, coffee, distilled drinks, wine, and fruit juice. Although PAHs are usually found in low concentrations in foods and beverages, they are one of the main factors that contribute to the onset of cancer in humans. This review covers the determination of levels of metals and polycyclic aromatic hydrocarbons in beer. The review was designed to cover the sources of metals and PAHs in beer as well as functions of metals and methods for the determination of metals and PAHs in beer. It was also designed to give insight to the health concerns of beer consumers.

Copper Binding in Sweet Worts Made from Specialty Malts.

Trace levels of copper can impact the flavor stability of beer. The main source of copper is malt, and the wort copper levels are established during mashing and lautering. This study focuses on sweet worts made from experimental roasted and caramel malts. Potentiometric titrations using ion-selective electrodes combined with electron paramagnetic resonance spectroscopy have been used to investigate Cu(II) binding in worts as well as the impact of Cu(II) ions on the wort oxidative stability. High-temperature treatment during malting decreased Cu(II) binding affinities in the worts, with roasted malt worts having lower affinities than caramel malt worts of similar color and pH. Electron paramagnetic resonance spectra indicated dipeptides as the main Cu(II) chelators. A positive correlation between Cu and free amino nitrogen levels in worts is demonstrated. In dark worts with high rates of radical formation, Cu(II) had pronounced antioxidative effects. In contrast, moderate prooxidative effects were observed when adding Cu(II) to pale worts with inherently low rates of oxidation.

Impact of Dry Hopping on Beer Flavor Stability.

To investigate the chemical and sensorial impact of dry hopping time on typical pale ale, a standardized beer was produced and separated into ten vessels. Nine vessels were dry hopped, and one vessel remained un-hopped as a control. Impact of dry hopping contact time was investigated over 96 h. Polyphenols and iso-α-acid t/c ratio were analyzed in both Young and Aged beer samples. Total polyphenol content generally increased in both young and aged treatments compared to controls. Analysis of the t/c ratio suggests that both Young and Aged beers were chemically preserved to some degree after approximately 12 h at the given dry hopping rate regardless of age. Within the Aged beer trials, 96 h of dry hop contact yielded a significant increase in t/c ratio compared to all other Aged trials. This suggests that a 4-day dry hop regime may yield additional oxidative protection of iso-α-acids in beers stored unrefrigerated for 30 days. Descriptive analysis was also performed with an 8-person, trained panel; however, beers were sensorially distinguished by their aging time as opposed to their dry hopping time.