Brewing Procedure Research Articles

Factors Influencing Consumer Preferences for Espresso and Omni Roasted Coffee: A Comprehensive Analysis

This qualitative study conducted in Buraydah, Saudi Arabia, explores coffee customers' shifting preferences, with a focus on the growing popularity of espresso and multi-roasted coffee. Through interviews with consumers, baristas, and coffee roasters, the study investigates the motivations behind these choices, which include health concerns, flavor exploration, and a dislike for highly acidic coffees. The findings highlight the appeal of concentrated flavor, higher caffeine concentration, and the ability to appreciate the varied qualities of coffee beans from different places. Omni roasted coffee, with its medium-dark roast, has a balanced flavor profile that works well with a number of brewing methods. The concept of coffee terroir, which highlights the distinct flavors associated with individual origins, influences customer preferences. These findings have ramifications for coffee growers and baristas, who can meet shifting customer needs by acquiring high-quality beans and perfecting brewing procedures. This study leads to a better knowledge of changing coffee preferences and gives practical insights for industry stakeholders.

Brewing Excellence: Improving Coffee Quality with the V60 Stirred-agitation Technique

Manual coffee brewing is the preferred method owing to its capacity to produce a more delicate and diverse range of flavors. While extensive research has been conducted on the process of coffee brewing, there has been limited discourse on the impact of agitation techniques on the quality of the steeping phase. The primary objective of this study is to explore the influence of agitation methods, specifically V60 and Kalita, on the quality of the steeping process. A survey-based investigation was conducted, analyzing sensory attributes such as flavor, aftertaste, acidity, body, balance, sweetness, overall flavor, acid intensity, and body level. A panel of twenty skilled baristas participated as evaluators. The findings of this research demonstrate that agitation plays a crucial role in achieving optimal extraction during the coffee brewing procedure. The particular agitation method employed distinguishes the brewing process and the final steeping outcome. Notably, the use of stirred agitation in the V60 method results in a well-balanced steeping flavor characterized by an acidic orange aroma and a subtle undertone of brown sugar, all without leaving a lingering, cloying aftertaste. The brewed coffee produced using this method exhibits a moderate level of acidity and body, alongside a subtly sweet flavor profile that contributes to an enhanced overall taste experience.

GC-MS-Olfactometric Characterization of Volatile and Key Odorants in Moringa (Moringa oleifera) and Kinkeliba (Combretum micranthum G. Don) Herbal Tea Infusions Prepared from Cold and Hot Brewing

Herbal teas are a popular global drink and are widely used in many traditional medicines. Key odorants are one of the main parameters to elucidate the final herbal tea’s overall quality and consumer acceptance. In the present study, for the first time, the brewing effect on volatile, key odorants, total phenolic contents, and antioxidant potential of Moringa (Moringa oleifera) and Kinkeliba (Combretum micranthum G. Don) herbal teas was comprehensively investigated. Two different infusions were studied and labeled as 25 °C/24 h (room temperature) and 98 °C/10 min (hot temperature). A total of 45 and 44 aroma compounds were detected in Moringa cold and hot teas, respectively, whereas 39 volatiles were determined in both infusion techniques for Kinkeliba herbal teas. The total amount of volatile compounds in both cold-infused herbal teas was higher than those in the hot-infused ones. Based on GC-MS-Olfactometry results, 19 and 21 key odorants in total were found in Moringa and Kinkeliba teas, respectively. The principal key odorants in Moringa teas with the highest flavor dilution (FD) factors were (E)-2-hexen-1-ol (herbal/fresh aroma), 3-hexanol (green/grassy), 2-phenyl ethanol (floral/rose), while in Kinkeliba teas they were 2-hexanol (herbal/green) and 3-penten-2-ol (green/fresh). The total phenolic content and antioxidant potential in Moringa and Kinkeliba teas increased using hot infusion. Principal component analysis showed that each tea infusion was clearly discriminated in terms of its volatile profiles. Our findings demonstrated that the brewing procedures had a significant impact on the key odorants of Moringa and Kinkeliba infusions.

A Modified Brewing Procedure Informed by the Enzymatic Profiles of Gluten-Free Malts Significantly Improves Fermentable Sugar Generation in Gluten-Free Brewing

The mashing step underpins the brewing process, during which the endogenous amylolytic enzymes in the malt, chiefly β-amylase, α-amylase, and limit dextrinase, act concurrently to rapidly hydrolyze malt starch to fermentable sugars. With barley malts, the mashing step is relatively straightforward, due in part to malted barley’s high enzyme activity, enzyme thermostabilities, and gelatinization properties. However, barley beers also contain gluten and individuals with celiac disease or other gluten intolerances should avoid consuming these beers. Producing gluten-free beer from gluten-free malts is difficult, generally because gluten-free malts have lower enzyme activities. Strategies to produce gluten-free beers commonly rely on exogenous enzymes to perform the hydrolysis. In this study, it was determined that the pH optima of the enzymes from gluten-free malts correspond to regions already typically targeted for barley mashes, but that a lower mashing temperature was required as the enzymes exhibited low thermostability at common mashing temperatures. The ExGM decoction mashing procedure was developed to retain enzyme activity, but ensure starch gelatinization, and demonstrates a modified brewing procedure using gluten-free malts, or a combination of malts with sub-optimal enzyme profiles, that produces high fermentable sugar concentrations. This study demonstrates that gluten-free malts can produce high fermentable sugar concentrations without requiring enzyme supplementation.

Analysis of phenolic compounds in beer: from raw materials to the final product

Two types of lager pale beers were produced at industrial scale according to German Beer Purity Law using the same brewing procedure, but different hop varieties. Beer phenols issued from malt and hop can contribute directly to several characteristics of beer, mainly flavor, astringency, haze, body, and fullness. The aim of this paper was to analyze simple phenolic compounds, total polyphenols and total flavonoids contents, antioxidant activity in raw materials (malt and hops) and in samples taken out from several production stages (after wort production, boiling, fermentation, filtering and pasteurisation). Eighteen different phenolic compounds which belong to the groups of hydroxybenzoic and hydroxycinnamic acid derivates, flavan-3-ols, flavonols and procyanidins dimers were analysed. Among all tested phenolic compounds, 9 compounds were identified in malt, 13 in hops, while 10 in samples taken from the brewing process. Based on the obtained results, it is suggested that the choice of hops is very important for obtaining the desired beer quality and to establish its shelf life.

Elucidation of key odorants in Beninese Roselle (Hibiscus sabdariffa L.) infusions prepared by hot and cold brewing

Roselle (Hibiscus sabdariffa L.) is an edible flower belonging to the large family of Malvaceae. Aroma is one of the crucial parameters to determine the final tea overall quality and the consumer's preference and it is affected by different processing factors (drying, heating, brewing etc.). The aim of this study was to compare hot and cold brewing procedures on the aroma and aroma-active compounds of Beninese Roselle for the first time. Three different infusions were prepared and coded as R16M (16 min/98 °C), R40M (40 min/98 °C) and R24H (24 h/at ambient temperature). The aroma compounds of the infusion samples were extracted by liquid liquid extraction (LLE) method and determined by gas chromatography-mass spectrometry (GC-MS). A total of 38, 38 and 39 aroma compounds including alcohols, furans, acids, ketones, aldehydes, volatile phenols, lactones, pyranone, pyrrole, terpene and ester were detected in R16M, R40M and R24H infusions, respectively. The total aroma concentration of the cold infusion sample (R24H) was higher than those of two hot infusions. A significant reduction was found in the amount of these compounds in the sample prepared by hot infusion with 16 min (R16M). In all three samples, furans were identified as the dominant aroma group followed by alcohols. Based on the results of the aroma extract dilution analysis (AEDA), a total of 22 and 23 different key odorants were detected in hot infusions (R16M and R40M) and cold infusion (R24H) (ambient temperature), respectively. The powerful key odorants with regard to FD (flavor dilution) factors in all samples were prevailingly furans, alcohols, and aldehydes. The highest FD factors were found in furfural and 5-methyl-2-furfural providing caramel and bready notes. Principal component analysis (PCA) showed that Roselle infusions could clearly be discriminated in terms of their aroma profiles. The findings of this study demonstrate that the brewing procedures have a important impact on the final aroma and key odorants of Roselle infusions.

Effect of the brewing process on the acrylamide content in coffee beverages

AbstractOne of the latest neurotoxic and carcinogenic substances discovered in food is acrylamide (AA). The main pathway for AA formation in foods is the Maillard reaction (MR). Heat treated carbohydrate-rich foods such as potato, cereal and bakery products, together with coffee contain high levels of acrylamide. The high consumption of coffee in many countries makes it a potentially significant source of daily exposure to acrylamide. The purpose of the present investigation was to study the influence of the brewing method on the acrylamide level in coffee beverages. The experiment was performed with six different roasted coffee from local supermarkets. For coffee beverages preparation four different methods were used: boiled coffee (Turkish coffee), steeping (French press coffee), infusion (filtered coffee), and Italian pressure method (espresso coffee). Each time coffee beans were mechanically powdered and 100 ml brew was prepared using 6 g of ground coffee. AA contents in the brew coffee samples were determined by the RP - HPLC - DAD method. The results for AA contents were presented as mean values ± standard deviations (SDs) of six independent samples, analysed in triplicate (n = 18). Obtained results showed that the method of brewing coffee influences the level of AA in infusions. AA concentrations for Turkish coffee (4.10 μg/100 ml), French press (3.19 μg/100 ml) and filtered coffee (2.95 μg/100 ml) were higher than for espresso (2.13 μg/100 ml). Results showed also that the highly water-soluble acrylamide is easily extracted from the ground coffee to the liquid phase of the beverage. The extraction percentage variation according to the brew method was: from 52% for espresso to 95% for Turkish coffee. The brewing procedure for espresso extracted acrylamide incompletely from ground coffee comparing to other brewing methods, due to the short contact time between coffee and water. When compared with other common coffee beverages, espresso is the most concentrated brew. However, its acrylamide content per cup may be lower, due to the lower level of this substance extraction to the brew. The brewing time has a significant influence on the extraction level of AA for the beverage.

Brewing time and temperature optimization of Robusta Dampit Coffee on several drip techniques

This study aims to optimize brewing temperature and time for 5 different drip techniques specifically to obtain optimum total phenolic content and antioxidant activity. These are including Kalita Wave, Chemex, Woodneck Drip Pot, Vietnam Drip and V60. Optimization was conducted due to variability of brewing procedure among barista/coffee brewer. In addition, sensory profiling was also carried out. The optimum time and temperature for Kalita Wave and Vietnam Drip were observed at 100°C for 180 s. Meanwhile, Chemex and V60 were optimum for 150 s brewing at 100°C and 90°C consecutively. The optimum temperature of Woodneck Drip Pot brewing was the lowest as 80°C for 180 s. Sensorially, Chemex and Kalita Wave tend to be similar, while the other three tend to be distinctive.

Rice malting optimization for the production of top-fermented gluten-free beer.

A safe method to obtain gluten-free beer led to the use of naturally gluten-free grains, such as rice, but the specific malting program for rice is long and requires a large amount of water, and the resulting beer showed a flat flavour profile. In this study, an optimization of the malting and brewing procedure is proposed to overcome the aforementioned issues. Different steeping conditions and kilning temperatures are considered, and a top-fermented beverage from rice malt is obtained for the first time. The malting procedure has been optimized by assessing the use of short-time steeping as an alternate to long air rest to obtain sufficient moisture content in the green malt, saving water consumption. The malt obtained allowed a regular fermentation, as confirmed by the sensorial analysis, which did not reveal any off-flavours. The use of a top-fermenting yeast formed high content of higher alcohol and relatively low amount of esters. This study confirms the potential of rice for the production of malt and beer. The optimized malting programme allowed water saving. The production of a top-fermented rice malt beer was a successful attempt to introduce a new flavoured product for consumption by individuals affected by coeliac disease. © 2018 Society of Chemical Industry.

Mycotoxins in malting and brewing by-products used for animal feed

Malting and brewing by-products (germ/rootlets, spent grains and spent yeast) represent a valuable and nutritious source of food for the livestock. The incidence of mycotoxins in animal feed is not an unusual phenomenon, and for that reason, feed obtained from malting and brewing process is subjected to mycotoxicological anyalysis. Objectives of this study were to establish the impact of the initial F. culmorum contamination and fungicide treatment on trichothecenes, namely deoxynivalenol (DON), 3-acetyl deoxynivelanol (3-ADON), nivalenol (NIV), diacetoxyscirpenol (DAS), fusarenon X (FUS X), HT-2 and T-2 . Their concentrations were measured in water after steeping, germ/rootlets, spent grains and spent yeast. Two wheat genotypes (A and B) were treated in four different ways in the field: control (a), treated with fungicide (b), inoculated with F. culmorum spores and treated with fungicide (c), and inoculated with F. culmorum spores (d). Standard malting procedure for wheat malt was implemented, followed by degermination process and brewing procedure. Mycotoxins were determined using multi- mycotoxin LC-MS/MS method. DON proved to be the most occurring mycotoxin in all of the samples and the highest concentration was found in steeping water of sample A(d) where detected concentration of DON was 20326 µgL-1. Germ/rootlets contained DON, 1384 μg/L in B(d) and 5636 μg/L in A(d) sample. Spent grains showed elevated DON value (1178 μg/L) for B(b) sample. Spent yeast showed increased DON values for A(d) sample (705 μg/L) but also for B(d) sample (1180 μg/L).

Ultra-high-performance liquid chromatography-high-resolution mass spectrometry based metabolomics as a strategy for beer characterization

An ultra-high performance liquid chromatography–high resolution mass spectrometry (UHPLC-HRMS) method was applied to the analysis of beers. Chromatographic profiles were recorded in both positive and negative electrospray modes and the resulting data was evaluated according to an untargeted metabolomic approach applied to the discrimination and characterization of beers. Principal components analysis and partial least squares–discriminant analysis were used for exploratory characterization and classification of beers according to the brewing procedure. Results showed that the chemometric models were able to distinguish among beer types. The study of MS features indicated that various detected markers were relevant for beer discrimination. Among them, for example, p-coumaric and ferulic acids, and 5-methylthioadenosine were tentatively identified as characteristic descriptors of Pilsner and Belgian ale beers, respectively. These findings were further confirmed by comparison of the UHPLC-HRMS data with those of standards and/or by MS/MS experiments. Conclusions extracted were validated on an independent set of samples. This work shows the applicability of untargeted metabolomic strategies to the characterization of beers at the molecular level. Copyright © 2016 The Institute of Brewing & Distilling

Technological and Engineering Trends for Production of Gluten-Free Beers

Beer is the main alcoholic beverage consumed worldwide. It is essentially composed of malt, adjuncts or grist, hops, water and metabolites produced by yeast. Produced regularly with barley, it is unsuitable for patients with celiac disease due to the presence of storage proteins known as hordeins. A recent boom in the production of gluten-free beers has been attributed to the awareness of celiac disease and the significant boost in the gluten-free market size. Several strategies have been recognized as suitable gluten-free brewing procedures: by using non-gluten grains, non-grain sources such as sugars, syrups and honey and enzymatic and microbial treatments of barley worts to reduce to non-significant levels (<20 ppm/L), the peptides or epitopes which trigger celiac disease. Since the traditional brewing process uses barley, the use of other grains, such as rice, maize, sorghum, buckwheat or different types of millets, involves differences in both malting and mashing procedures especially in terms of process times and temperatures. Sorghum has been especially recognized for its potential to substitute barley since it is widely used in many countries of Africa to create traditional opaque beers, but compared to barley malt lacks of sufficient diastatic power due to the lower synthesis of both α- and β-amylases, and additionally, the starch requires higher temperatures for gelatinization. Likewise, rice, maize, millets and buckwheat are being used as source of both malt and grist with similar problems as sorghum. Potential future approaches involve the genetic engineering of barley in order to remove the peptides of the storage proteins that cause the allergic reaction on celiac patients and the employment of recombinant yeasts or other fermenting microorganisms that express prolyl endoproteinases which hydrolyze celiac immunoreactive epitopes into non-harmful peptides.

Neapolitan coffee brew chemical analysis in comparison to espresso, moka and American brews

The aim of the present study was to characterize the chemical composition of Neapolitan coffee brew in comparison to espresso, American, and moka coffee brews. Despite the similarity of brewing principle of Neapolitan and American coffee-making techniques, i.e. percolation of hot water through ground coffee, the characteristics of Neapolitan coffee brew in terms of antioxidant activity, total phenolic compounds and total solids were more similar to moka coffee brew. Espresso and moka showed higher antioxidant activity, and espresso exhibited higher caffeine concentration, total phenolic compounds, and total solids with respect to other coffee brews studied. For the first time a characterization of the Neapolitan coffee aroma, a traditional Italian brewing procedure, was reported. A significant higher amount in hexanal, β-damascenone and some pyrazines was found in Neapolitan coffee aroma with respect to other procedures. These compounds could be considered as a distinctive characteristic of Neapolitan coffee aroma. Moka was characterized by higher guaiacol content with respect to other procedures, while espresso showed significantly higher levels in aldehydes and 2-furanmethanol acetate.

Determination of Pesticide Residue Transfer Rates (Percent) from Dried Tea Leaves to Brewed Tea

This paper presents a study on pesticide residue transfer rates (%) from dried tea leaves to brewed tea. In the study, a brewing procedure simulated the preparation of a hot tea drink as in routine. After brewing, pesticide residues were extracted from brewed tea using a method known as QuEChERS (quick, easy, cheap, effective, rugged, and safe). An UHPLC/ESI-MS/MS method was developed and validated to identify and quantify up to 172 pesticides in both tea leaves and brewed tea samples. Quantification was achieved using matrix-matched standard calibration curves with isotopically labeled standards or a chemical analogue as internal standards, and the calibration curves consisted of six points (0.4, 2.0, 8.0, 16.0, 24.0, and 40.0 μg/L equivalent in sample). The method was validated at four concentration levels (4.0, 12, 20.0, and 32.0 μg/L equivalent in sample) using five different brewed tea matrices on two separate days per matrix. Method performance parameters included overall recovery, intermediate precision, and measurement uncertainty, which were evaluated according to a nested experimental design. Approximately, 95% of the pesticides studied had recoveries between 81 and 110%, intermediate precision ≤20%, and measurement uncertainty ≤40%. From a pilot study of 44 incurred tea samples, pesticide residues were examined for their ability to transfer from dried tea leaves to brewed tea. Each sample, both tea leaves and brewed tea, was analyzed in duplicate. Pesticides were found to have different transfer rates (%). For example, imidacloprid, methomyl, and carbendazim had transfer rates of 84.9, 83.4, and 92.4%, respectively.

Fate of enniatins and beauvericin during the malting and brewing process determined by stable isotope dilution assays

The fate of enniatins A, A1, B, B1 and beauvericin during the malting and brewing process was investigated. Three batches of barley grains were used as starting material, one was naturally contaminated, two were artificially inoculated with Fusarium fungi. Samples were taken from each key step of the malting and brewing procedure, the levels of the toxins were determined with stable isotope dilution assays using liquid chromatography–tandem mass spectrometry detection. Significant increases of the toxins were found during germination of two batches of barley grains, resulting in green malts contamination up to a factor of 3.5 compared to grains before germination. Quantitative PCR analyses of fungal DNA revealed in all batches growth of Fusarium avenaceum during germination. After kilning, only 41–72% of the total amounts of the toxins in green malts remained in kilned malts. In subsequent mashing stage, the toxins in kilned malts predominantly were removed with spent grains. In the final beer, only one batch still contained 74 and 14 μg/kg of enniatin B and B1, respectively. Therefore, the carryover of these enniatins from the initial barley to final beer was less than 0.2% with the main amounts remaining in the spent grains and the malt rootlets.

Caffeine and chlorogenic acids intake from coffee brew: influence of roasting degree and brewing procedure

SummaryThe influence of coffee cultivar, roasting degree and brewing procedure in the presence and transfer of caffeine and caffeoylquinic acids (CQAs) from ground roasted coffee to the brew was evaluated. Two coffee cultivars were roasted in three roasting degrees and brewed using two different procedures. Compounds were determined simultaneously by HPLC‐DAD. Caffeine levels ranged from 87.3 to 122.5 mg/100 mL for Coffea arabica cv. Catuaí Amarelo and from 123.3 to 192.0 mg/100 mL for C. canephora cv. Apoatã. The sum of CQA isomers ranged from 24.2 to 41.3 mg/100 mL for brews prepared with dark roasted coffee and from 187.7 to 295.6 mg/100 mL for light roasted ones. Brews prepared by boiling showed higher content of the compounds than the corresponding filtered ones. C. arabica cv. Catuaí Amarelo light roasted coffee brew presented the lowest caffeine/CQA ratio, regardless of the brewing procedure used, in comparison with the highest ratio of the dark boiled brews.

Comparison of analytical parameters of beer brewed in two different technological ways at two pub breweries

This publication deals with brewing beer by infusion and decoction technologies of mash production in microbreweries. Samples of two microbrewery beers are compared, namely Richard beer (Brno-Žebětín) produced in a double mash manner appropriate for the Czech brewing type, and beer samples taken at the laboratory microbrewery of Mendel University in Brno (MENDELU), where beer is produced in a simpler and less energy – demanding infusion method. At all the beer samples the basic analytical parameters of real extract, ethanol content, degree of fermentation and the extract of original hopped wort were measured using an automatic beer analyzer. The results coming out of the automatic beer analyzer are compared with the results of the beer samples analysis performed by liquid chromatography, by which the contents of oligosaccharides, maltose, glycerol and ethanol were measured. Both methods provide a number of analytical results for the comparison of decoction and infusion techniques, and analytical characteristics of both the brewing procedures. Emphasis is placed on statistical data processing and comparison of different types of beer and particular brews between each other, both in terms of production technology as well as beer sampling throughout the year.

Quality and Antioxidant Property of Three Types of Tea Infusions

Tea infusions were prepared from green, oolong and black teas made from the leaves of Camellia sinensis L. (cultivar Shy-Jih-Chun) using the conventional brewing procedure. Three types of tea infusions were different in pH values, soluble solids, color values and visual appearance. With regard to antioxidant activity, reducing power and scavenging ability, the efficacies of tea infusions were in the descending order of nonfermented > semi-fermented > fully fermented. However, the order of efficacies in chelating ability was reversed. Besides, black tea infusion showed a higher Trolox equivalent antioxidant capacity value. Caffeine contents were similar (42.43‐43.13 mg/100 mL). Contents of ascorbic acid, total phenols and total catechins were in the descending order of green > oolong > black tea infusions. All sensory scores (>4.5) were in the descending order of oolong > black > green tea infusions. Overall, the results were valuable for further application and comparison.

Dissolved Silicon and Its Origin in Belgian Beers—A Multivariate Analysis

Beer is a quintessential part of Belgian heritage. We performed a detailed analysis of factors controlling Si content in Belgian beers as a case study to coincide with the 2011 IBiS meeting in Antwerp (Belgium). Beer is one of the richest dietary sources of Si. Three decades of research have yielded evidence of a role for Si in human physiology: it plays an essential role in bone mineral density and reduces the biological availability of aluminium. We analysed 119 Belgian beers: highest dissolved Si concentrations were found in high fermentation, traditionally brewed ales. Concentrations ranged between 214 and 2,071 μmol L − 1. This is probably due to the complexity and length of the brewing procedure: longer, more complicated processing and presence of brewing sediment in the bottle allows more Si to dissolve out of the base products like hop, barley or even rice. As a side effect of fermentation, alcohol content was related to Si content.

Polycyclic aromatic hydrocarbons in coffee brew: Influence of roasting and brewing procedures in two Coffea cultivars

During coffee’s roasting process undesirable compounds such as polycyclic aromatic hydrocarbons (PAHs) may be formed and later transferred to the brew. The influence of coffee cultivar, roasting degree and brewing procedure in the presence and transfer of four PAHs from ground roasted coffee to the brew was evaluated. Ground roasted coffees in three roasting degrees were obtained from Coffea arabica cv. Catuaí Amarelo IAC-62 and Coffea canephora cv. Apoatã IAC-2258 and their respective coffee brews were prepared by two brewing procedures (filtered and boiled). PAHs levels in the brews were determined by HPLC-FLD. At least one PAH was detected in all coffee brew samples. PAHs summed levels ranged from 0.015 to 0.105 μg/L (C. arabica brews) and 0.011 to 0.111 μg/L (C. canephora brews). The difference among the levels detected in different roasting degrees was not statistically significant, except between dark and roasted filtered brews. Coffee brews prepared with C. arabica ground roasted beans presented mean summed PAHs levels higher than the ones prepared with C. canephora, independently of the brewing procedure used. The caffeine levels in the beverages do not seem to influence the transfer.