Top-fermented Beers Research Articles

Effect of Dry Hopping Conditions on the Hop Creep Potential of Beer

Dry hopping is a technique of adding hops to beer during or after fermentation to enhance aroma and flavor. It results in an undesired phenomenon called hop creep: attenuated beer undergoes a secondary fermentation. The aim of the research was to evaluate practical aspects of hop creep. In laboratory conditions hop creep was evaluated in pasteurized and unpasteurized beers and the effect of hop separation from beer after 3 days of dry hopping was verified. Hop creep analyzed in beers brewed on a pilot scale (20 L) and an industrial scale (10 hL) allowed to observe the course of hop creep in various scales of production, and to compare the process in pressure and non-pressure conditions. The decrease in the apparent extract of beer caused by hop creep occurs only in unpasteurized beers, separation of hops after 3 days reduces the extent of hop creep. Hop creep occurs faster in top-fermented beers and is equally intense regardless of the scale of production. The use of pressure conditions during dry hopping extends the duration of the hop creep without affecting the final extract content of the beer (the final attenuation of beer is the same in pressure and non-pressure conditions).

A table-top sensor for the detection of hydrophobins and yeasts in brewery applications

In this work, we present a biomimetic sensor for the sensitive and fast (< 15 min) detection of yeast cells (S. cerevisiae) and hydrophobins (e.g. HFB) in food and beverages. While unwanted yeast contaminations can cause off-flavors and stability issues, hydrophobin contaminations are a less-known but equally serious economic concern in beer production. Hydrophobins are small proteins, that are produced by pathogenic fungi that often infect barley. Due to their high temperature stability, HFBs survive all stages of brewing and, after bottling, they cause excessive foaming due to interactions between the HFBs, CO2, and glass surfaces. Tiny HFB concentrations are sufficient to cause this “gushing” and up to 10% of beer production is therefore discarded. Hence, an early-stage HFB detection, preferably even before malting, would reduce the loss of resources. However, existing tests are time-consuming and have sub-optimal accuracy. The novel sensor platform has a user-friendly design that combines impedimetric readout with wire-type electrodes, coated with poly-pyrrole layers that are imprinted with Trichoderma reesei hydrophobin I (HFBI) molecules or with yeast cells. In complex food samples, the sensor reaches detection limits of 50 yeast cells/mL (in yoghurt solution) and below 30 ng/mL HFBI in top-fermented beer samples. Cross-selectivity tests with proteins of similar size show a response to Hyd5 (another hydrophobin) and discrimination against insulin. As a final proof of application, we demonstrate hydrophobin detection directly in extracts of industrial malt samples with and without a natural hydrophobin contamination.

RESEARCH ON THE POSSIBILITY OF USING LACTOSE IN PRODUCING A CRAFT VARIETY OF MILKSHAKE IPA STYLE

The article presents the results of studies to study the possibility of using lactose in the brewing industry, as a component that forms the original organoleptic characteristics of top-fermented beer. The influence of the introduction of various amounts of lactose on the change in physicochemical, biochemical indicators at the stage of the main fermentation, as well as at the stage of maturation of the finished beer, on the physiological characteristics of top-fermented brewing yeast and on the organoleptic characteristics of the finished beer was investigated. It was found that the most optimal stage of lactose introduction is the stage of main fermentation.

The effect of different oat (Avena sativa L) malt contents in a top-fermented beer recipe on the brewing process performance and product quality

In brewing, barley (Hordeum vulgare L.) malt is increasingly being replaced by other cereals. This stems from the desire to add new characteristics to beer and/or to improve the brewing process or cost of production. This research aimed to analyse the effect of different percentage shares (0, 10, 50 and 100 %) of oat (Avena sativa L.) malt in the recipe on the course of top-fermented beer production. The analysis conducted did not show any negative effect of the application of 10 % share of oat malt in the recipe on the brewing process and the quality of the final product, as compared to the no-oat-malt recipe. On the other hand, in the case of higher oat malt content, prolongation of lautering time (up to ca. 120 min), lower quantity of wort (up to ca. 30 %), its extract content (up to ca. 35 %), and thus alcohol concentration, as well as intensified colour of beer were observed. In oat and barley beers, the content of D-chiro-inositol was below the detection threshold, while small amounts of myo-inositol were determined in the samples. Furthermore, the application of oat malt affected the ionic content of the wort and did not affect the level of phenolic compounds.

High-gravity brewing without adjuncts – The effect on beer parameters

High-gravity brewing (HGB) is a common practise in industrial breweries. The aim of this study was to examine the effect of HGB on analytical and quality parameters of all-malt beer. Parameters were evaluated in bottom-fermented (BF) beer and some data were compared with results from top-fermented (TF) beer. In both, BF and TF beer, two brews were produced where a higher original gravity (OG) beer was diluted to the level of a lower OG beer. Increased ester production was the principal reason for changes in the flavour profile. Especially higher levels of acetate esters (ethyl acetate, isoamyl acetate) affected beer aroma, creating fruity and solvent-like odours. Higher alcohol and acetaldehyde contents were not affected by HGB. The use of HGB for BF beer did not affect important quality parameters such as thiobarbituric acid number (TBA) or foam stability. The content of beer ageing markers (carbonyl compounds) was also not affected by the use of the HGB technology. In sensorial evaluation, differences in flavours of BF HGB beer were evaluated in a triangle test. Beer without dilution was preferred by tasters, commenting on better harmony in bitterness and beer body.

Influence of malt composition on the quality of a top fermented beer.

The beer is a widely consumed drink, appreciated for its sensory characteristics, and it also contains beneficial compounds for health derived from its raw materials. In this work, the influence of coloured malt on the main quality parameters of a top-fermenting beer was evaluated. The beers were produced increasing the percentage of coloured malt (0, 5, 15% Caraamber®) respect to the pale ale base malt. The beers had an alcohol content ranging from 6.2 to 6.8 vol%; the results highlighted a deeper colour, increased bitterness and turbidity in beer with the highest amount of Caraamber malt. This latter showed the highest polyphenols (453.8mg GAE/L) and antioxidant activity (840.1µmol TE/L) and, on the other hand, the lowest foam stability. The volatiles profile showed a higher amount of aldehydes and ketones in beer with the highest percentage of caramel malt but the lowest in higher alcohols and esters. No differences were found in the fruity-esters, alcoholic and caramel sensory notes; while the beer made with 15% of coloured malt was perceived sweeter and with less fruity citrus notes than other beer samples.

Investigations on the Impact of the Special Flavor Hop Variety Huell Melon on the Odor-Active Compounds in Late Hopped and Dry Hopped Beers.

Bottom-fermented and top-fermented beers, both either late or dry hopped with Huell Melon hops, and respective reference beers without late or dry hopping were subjected to a comparative odorant screening by aroma extract dilution analyses. On the basis of differences in the FD factors, 14 odorants were identified as hop-derived. Among them were ethyl 2-methylpropanoate, methyl 2-methylbutanoate, ethyl 2-methylbutanoate, propyl 2-methylbutanoate, myrcene, linalool, and geraniol. Differences between late hopped, dry hopped, and reference beers were substantiated by quantitation. Results showed minimal transfer of myrcene from hops into beer. Moderate transfer was observed for propyl 2-methylbutanoate, geraniol, and linalool. Process-induced changes of ethyl 2-methylpropanoate, ethyl 2-methylbutanoate, and methyl 2-methylbutanoate were beyond a direct transfer from hops into beer, suggesting a formation from the corresponding hop-derived carboxylic acids by yeast. Spiking experiments revealed that linalool and propyl 2-methylbutanoate contributed particularly to the characteristic aroma of beers flavored with Huell Melon hops.

Specialty rice malt optimization and improvement of rice malt beer aspect and aroma

Although brewing beer with cereals other than barley malt is an established trend, producing a tasty product in this manner represents an ongoing research challenge. Rice malt beer represents a gluten-free beverage for individuals with celiac disease. Previous research on rice malt beer has shown a notably flat sensory profile and a low pale color. The use of special rice malts could be a means of enhancing the flavor, taste, color and body of a rice malt beer. To the best of our knowledge, no research has been performed on the use of rice for the production of specialty malts. An experimental study to obtain two different types of special rice malt, namely, caramelized and dark, was conducted. Quality attributes of the obtained malts were determined. A top fermented beer from pale rice malt and special rice malts was produced and analyzed to evaluate the sensorial properties. The resulting beer displayed a malted profile and an amber color. The use of the special rice malts enhanced the flavor and the color, in addition to the stability and the nutritional value, of the beer, thanks to their high polyphenol content and their good antioxidant capacity.

Robotics and computer vision techniques combined with non-invasive consumer biometrics to assess quality traits from beer foamability using machine learning: A potential for artificial intelligence applications

Foam-related parameters greatly influence other sensory attributes of beer such as aromas, flavors and mouthfeel; therefore, the visual assessment of beers is one of the most important quality traits, since it creates the first impression of consumers in determining the willingness to taste the product and perceived quality. Sensory analysis has been extensively used to assess consumers acceptability; however, this can only obtain their self-reported conscious responses. Therefore, biometric techniques have been used to assess the subconscious responses, which provide more information from consumers when integrated with sensory evaluation questionnaires. In this study, non-invasive biometrics along with a sensory questionnaire were used to assess consumers perception to visual attributes of 15 beers from pouring videos obtained using the RoboBEER (automatic robotic pourer). The sensory session was conducted with 30 participants using an integrated camera system, which consists of an infrared thermal camera and video recording coupled with a Bio-sensory computer application (App) and an eye tracking device. Objective physical parameters from beer pouring were obtained using the RoboBEER and computer vision algorithms. Results from the Just About Right (JAR) and acceptance tests showed that consumers preferred top fermentation beers, which have a medium foam height and stability, and tend to highly penalize bottom fermentation beers with lower foam. The principal components analysis explained a total of 52% of data variability. A correlation matrix was developed to assess significant correlations between the conscious, subconscious and physical data such as the positive correlation between perceived quality and heart rate, and the negative correlation between foam stability liking and foam drainage. Furthermore, an artificial neural network model (ANN) with 82% accuracy was developed using 28 parameters from the subconscious and objective physical data as inputs to classify beers per participant according to their level of liking of foam height (low and high). The combined use of these techniques showed to be an accurate and rapid tool to assess the visual sensory perception of beers based on the RoboBEER and biometric outputs from consumers with significant potential applications for fast screening within the beer industry.

Statistical evaluation of beer spoilage bacteria by real-time PCR analyses from 2010 to 2016

A total of 13,802 samples over seven years were investigated using real-time PCR for the presence of beer spoilage bacteria, providing a rare large-scale overview of the incidence of individual species. At the same time, the isolation site (early stages of the brewing process = type I and late stages = type II) and the type of contaminated beer and intermediate products (bottom-fermented or top-fermented) were evaluated using chi-squared analysis. The most frequently occurring species were Lactobacillus brevis (7 year average 41.9%), Lactobacillus (para-)casei (10.4%) and Lactobacillus backii (9.5%). L. (para-)casei was found at significantly higher rates in the early stages of the brewing process, whereas Lactobacillus lindneri, the Lactobacillus [L. (para-)plantarum and L. coryniformis] and the Pectinatus (P. cerevisiiphilus, P. frisingensis and P. haikarae) groups and Megasphaera cerevisiae predominated in the later stages and in package (significance level 95%). On a significance level of 95%, Pediococcus damnosus, M. cerevisiae and L. lindneri together with the Pectinatus and Lactobacillus groups grew predominantly in bottom fermented samples. L. brevis, in contrast, was found most frequently in top fermented beers. Copyright © 2018 The Institute of Brewing & Distilling

Modernización tecnológica y cambio empresarial en la industria cervecera barcelonesa, 1870-1913. Un enfoque chandleriano

The start of the production of bottom-fermented beer in Barcelona, at the beginning of the 1870s, resulted in a drink with organoleptic characteristics that made it more popular: less alcohol and more frothy and transparent than the top-fermented beer made until then. Its production resulted in greater investment in new technologies, including the production of artificial refrigeration, which led to a marked increase in fixed costs. This meant, on the one hand, external financing requirements. Furthermore, it encouraged the development of partnership strategies due to overproduction. Finally, launched mergers appeared, motivated by the emergence of economies of scale and leading to the formation of an oligopoly in 1910. These strategies, used to consolidate a new structure in the Barcelona brewing industry, have many points in common with the principles of big business enunciated by Chandler.

Influence of hop harvest date of the ‘Mandarina Bavaria’ hop variety on the sensory evaluation of dry‐hopped top‐fermented beer

To impart a special hop aroma to beer, dry-hopping is a technique that is becoming more and more popular with commercial breweries. Nevertheless, until now little was known about the factors that influence the reproducibility (and consistent product quality) of dry-hopping with flavour varieties. One factor that could influence the sensory impressions and aroma profile compositions of dry-hopped beers is the hop harvest date. Therefore, to determine the effects of different harvest dates of the flavour variety ‘Mandarina Bavaria’ on the aroma of top-fermented beer, laboratory-scale dry-hopping trials were performed. Besides tasting sessions of brewed beers, relative quantities of selected hop-derived, as well as beer-originated aroma compounds, were investigated by headspace–solid-phase microextraction–gas chromatography–mass spectrometry. Duo–trio tests between the beers hopped with pellets of different harvest dates showed no significant differences (α = 0.05) between them. In addition, these beers had similar profiles in a five-point profile tasting scheme. On the other hand, relative concentrations of some hop-derived aroma compounds – especially myrcene, which is known to be able to contribute to beer flavour – increased corresponding to a later harvest date, while beer originated volatiles were not different between the beers. Analytical results combined with the results of sensory evaluations led to the conclusion that the harvest date of Mandarina Bavaria was not a dominant factor in the dry-hopping aroma of top-fermented beers. High amounts of fermentation by-products are likely responsible for masking effects resulting in no sensory distinctness between the samples with different hop aroma compound concentrations. Copyright © 2016 The Institute of Brewing & Distilling

Taste-active Components of Beers from Emmer Wheat (Triticum dicoccum) Malt

Abstract Emmer wheat (EW, Triticum dicoccum) grows under adverse climatic and soil conditions in the hilly areas of Italy and other temperate regions. So far, EW has been used for pasta or bakery products. The malt obtained from EW was used to produce a light beer, a double malt beer, and beers with 50% (B50) and 30% (B30) EW malt combined with barley malt. These top-fermented beers showed a sweet, fruity, citrus character. The different sensory impact and chemical composition (betaglucans and flavanoids) of the beers was related to the germinative energy of EW and the different proportions of malted EW and barley malt. The light beer combines the moderate alcohol (3% vol.) with a good intake of natural antioxidants (total phenolic content, TPC, 85 mg l−1), whereas B50 showed a high TPC (109 mg l−1) and the highest beta-glucan content (27 mg l−1).

Quality Attributes of Low-Alcohol Top-Fermented Beers Produced by Membrane Contactor

The practice of dealcoholization is used nowadays to reduce the alcohol content in beverages, and osmotic distillation seems to be a convenient membrane process due to its mild operating conditions. The focus is on the quality of final beverage which may lack in taste, flavor, and body. The aim of this work was to evaluate the quality attributes of low-alcohol beers, dealcoholized by osmotic distillation and using stripping solutions specific for the beverage composition. Two types of top-fermented beer were used: Weiss beer, with a very fruity aroma and strong phenolic content, and Bitter beer, with a malt aroma. Regarding the stripping solutions, they were obtained by dilution of the original beer with water, in order to limit the volatile compound loss during the process. Moreover, low-alcohol Weiss beer was also produced by using carbonated stripping solutions (i.e., saturated with CO2 at ambient pressure). The results highlighted that color, bitterness, total phenols, and antioxidant activity were unchanged in the low-alcohol beers but volatile compounds were reduced to a different extent. The lower vapor pressure of some volatile compounds (i.e., 2-phenylethanol, aldehydes) can explain their retention in beer. The carbonation of stripping solutions did not significantly reduce CO2 loss, but aldehydes and total alcohols were better retained in low-alcohol Weiss beer. Esters and other volatile compounds were reduced so that the low-alcohol beer may result with a weak sensory profile, which can be compensated by a re-addition of CO2 before bottling.

Occurrence of Theaspirane and its Odorant Degradation Products in Hop and Beer.

In model oxidized media, six theaspirane-derived compounds were identified by gas chromatography-high resolution mass spectrometry: 4-hydroxy-7,8-dihydro-β-ionone, 6-hydroxy-7,8-dihydro-α-ionone, dihydrodehydro-β-ionone, two monoepoxides, and a derived alcohol. Only 4-hydroxy-7,8-dihydro-β-ionone and dihydrodehydro-β-ionone have been described previously in the literature. Investigation of hop revealed five of these compounds in free form together with theaspirane (especially in the Mosaic variety), while the Citra and Amarillo hop varieties emerged as very interesting for the release of theaspirane, 4-hydroxy-7,8-dihydro-β-ionone, and dihydrodehydro-β-ionone from glucoside precursors. For the first time, theaspirane, 4-hydroxy-7,8-dihydro-β-ionone, 6-hydroxy-7,8-dihydro-α-ionone, and both monoepoxides were found in a fresh commercial top fermentation beer (only theaspirane, 4-hydroxy-7,8-dihydro-β-ionone, and dihydrodehydro-β-ionone have recently been mentioned as Gueuze constituents).

Deoxynivalenol and zearalenone occurence in beers analysed by an enzyme-linked immunosorbent assay method

The occurrence of deoxynivalenol and zearalenone in samples of 91 beers commercialised in Poland was the topic of investigation. Most of beers were produced by domestic companies. The analysis was conducted using the enzyme-linked immunosorbent assay method (ELISA). Deoxynivalenol has been found in 100% and zearalenone in 11% of tested beer samples, with ranges of 6–70.2 μg/L and 0–0.546 μg/L, respectively. The mean levels of 20.66 μg/L for deoxynivalenol and 0.044 μg/L for zearalenone contribute on average of 8.6% and 0.04% of the estimated tolerable daily intake of both mycotoxins, considering an average daily intake of 0.25 l of beer per capita in Poland. The concentration of deoxynivalenol was found to be slightly higher in top-fermented beers. The deoxynivalenol content was also higher in dark-coloured beers both in the top-fermented and bottom-fermented beer samples. The regression analysis showed very little correlation between deoxynivalenol content and alcohol percentages by volume.

Gene cloning of phenolic acid decarboxylase from Bacillus subtilis and expression in top-fermenting yeast strain

Phenolic acid decarboxylase ( PADC ) gene, encoding phenolic acid decarboxylase, was cloned from Bacillus subtilis and ligated with a shuttle vector YEp352 to generate a novel plasmid YPADC. By analysis of sequencing and the restriction endonuclease digestion, the validity of construction was proved. Subsequently, the new vector was successfully transformed into wild-type top-fermenting yeast strain W303-1A; the mutant yeast strain W303+padc was obtained, which was tested on the laboratoryscale mashing and fermentation experiments. At the end of fermentation, the results showed an obvious increase of 4-vinylguaiacol content in top-fermented beers brewed with mutant yeasts. The final 4-vinylguaiacol concentration obtained with wild-type and mutant yeasts was 1.20 and 1.70mg/l, respectively. Additionally, the level of esters produced by the mutant strain was higher than that of the wild-type; there were therefore a marked clove-like and ester aroma in top-fermented beers brewed with the former. However, no evident differences were found in brewing characteristic between wild-type and mutant strains, especially the ability of utilizing fermentable sugar and reducing diacetyl. Taken together, these approaches indicated the possibility of cloning PADC gene and enhancing the concentration of 4-vinylguaiacol in top-fermented beers.size. Keywords : Clone, phenolic acid decarboxylase, top-fermenting yeast, 4-vinylguaiacol African Journal of Biotechnology Vol. 9(33), pp. 5284-5291, 16 August, 2010

Enhancing the Concentration of 4-Vinylguaiacol in Top-Fermented Beers—A Review

Despite being considered undesirable in bottom-fermented beers, 4-vinylguaiacol (4VG) is a well-known aroma compound found in top-fermented beers such as Belgian white (brewed with unmalted wheat), German Weizen, and rauch (brewed with malted wheat). Most of the published reports have investigated the brewing technology used to enhance the concentration of 4VG, but only a few have explored the genetic engineering of yeast strains to increase its content. In fact, expressing the phenylacrylic acid decarboxylase (PAD1) and phenolic acid decarboxylase (PADC) genes is the most efficient way to enhance the concentration of 4VG in top-fermented beers. Accordingly, this review focuses on the cloning and expression of PAD1 and PADC genes and compares the concentrations of 4VG in top-fermented beers brewed with parent and mutant yeasts in laboratory-scale mashing and fermentation experiments. The results indicate that the concentration of 4VG was markedly increased in top-fermented beers brewed with the mutant yeast.

Processing of a Top Fermented Beer Brewed from 100% Buckwheat Malt with Sensory and Analytical Characterisation

A top fermented beer was brewed from 100% buckwheat malt and sensory and analytical characterisation was carried out. Difficulties with lautering and filtration were encountered during the brewing process, which resulted in problems during fermentation and beer filtration. The beer was evaluated in the fresh and forced aged state for the following attributes: odour, purity of taste, mouthfeel, tingling, and bitterness. Analytical results indicated that the buckwheat beer compared quite closely to a typical wheat beer with regard to pH, FAN, fermentability and total alcohol. However, the extract of the buckwheat wort was lower, resulting in a final extract yield of 54.5%. GC analysis of the resultant beer revealed commonly encountered levels of the esters that give beer a fruity character. A low level of fusel alcohols, in comparison to a typical wheat beer, was detected. A high level of ethyl caprinate (coconut flavour) and lauric acid (fatty odour) was detected. Sensory analysis indicated that the buckwheat beer was acceptable with regard to odour, purity of taste, mouthfeel, tingling and bitterness. In conclusion, results of this study prove buckwheat's qualification as a gluten-free brewing material and with process optimisation, its readiness for marketing.

Formation of 4-vinyl and 4-ethyl derivatives from hydroxycinnamic acids: Occurrence of volatile phenolic flavour compounds in beer and distribution of Pad1-activity among brewing yeasts

This work represents a survey of the occurrence of hydroxycinnamic acids and volatile phenols in a variety of beer styles. The contribution of 4-vinylguaiacol to the overall flavour perception of top-fermented specialty beers was shown. Significant differences in hydroxycinnamic acids (both free and ester-bound) and volatile phenol content between different beers were observed. The variability in volatile phenol content between different beers and beer styles can be explained by the high incidence of Pad1 + phenotype and the variability of Pad1 activity observed among top-fermenting brewing yeast strains. The relative importance of thermal versus enzymatic decarboxylation can account for the differences found between bottom and top-fermented beers. Concerning the optimisation of volatile phenol levels in beer, the selection of a suitable brewing yeast strain is the most important means of creating a phenolic taste profile in beer. Given that a considerable amount of hydroxycinnamic acids in beer still occurs in ester-bound form, enhancing the enzymatic release of these phenolic flavour precursors during mashing can greatly enhance the phenolic aroma potential of wort.