Journal of The Institute of Brewing最新文献

The metabolite 3-deoxyglucosone (3-DG) is formed by carbohydrate caramelisation or the Maillard reaction. 3-DG is a precursor in the Strecker reaction forming beer ageing compounds, such as 2-methylbutanal or 3-methylbutanal. Although 3-DG is known as intermediate, recent studies have focused on 3-DG in beer. Foremost, the thermal load during wort boiling provides the best conditions for 3-DG formation and degradation, however, the reactivity of the dicarbonyl during the boiling process has not yet been explained. As a key intermediate, 3-deoxyglucosone could be a critical indicator for beer ageing stability. The 3-DG formation and reactivity during wort production depends on its precursor reactants (amino acids and glucose). The concentration in wort of these substances was varied using two malts with different malt modification along with two different mashing programmes. 3-Deoxyglucosone reactivity was observed by analysing dehydratisation to HMF (HPLC-UV), interconversion to 3-deoxygalactosone (3-DGal, HPLC-UV) and selected Strecker aldehydes (GC-SPME-MS). This study shows that wort boiling is the most important process in 3-DG formation as it contributes 47% of the final content compared with malting (28%) and mashing (25%). With degradation reactions, 3-DG is mainly interconverted to 3-DGal and, contrary to the literature, it could not be confirmed that enhanced 3-deoxyglucosone content affects Strecker reactions. The interconversion reaction during wort boiling determines the dicarbonyl potential of beer and influences the ageing stability. © 2021 The Authors. Journal of the Institute of Brewing published by John Wiley & Sons Ltd on behalf of The Institute of Brewing & Distilling.

Changes in hop-derived compounds of beer were evaluated over 10 months of storage at 3 and 20°C, revealing significant changes in the beers stored warm. Beer pH and colour increased, together with ‘hop creep’ through storage of unpasteurised dry-hopped beers. Hop bitter acids decreased moderately during storage at 20°C but not at 3°C and hop aroma compounds - key contributors to dry-hop flavour - were significantly depleted upon warm storage. Cold storage resulted in significant retention of these compounds in the beers, especially hop mono- and sesquiterpenes which exhibited the greatest losses after warm storage. The losses of hop aroma compounds were linked in part to association with polymeric crown cap liners (‘scalping’), the dynamic of which was further impacted by storage temperature. A wide range of hop aroma compounds were found to be abundant in the crown cap liners of bottled beers after storage, in contrast to canned beers which showed better retention of key hop aroma compounds (caryophyllene, myrcene and humulene) throughout storage. The impact of some of the chemical changes during storage was determined by sensory analysis. Changes in ‘bitter’, ‘tropical’ and ‘citrus’ fruit, ‘sweet’ and ‘malty’ attributes were all influenced by storage temperature and the given beer. Changes in ‘floral’, ‘fruity’, ‘sour/acidic’, ‘alcoholic’ and ‘lingering aftertaste’ were dependent on the beer, whilst changes in ‘spicy’ notes were dependent on storage temperature. These findings provide meaningful insights into the storage induced changes of dry-hop flavour in dry-hopped beers. © 2021 The Authors. Journal of the Institute of Brewing published by John Wiley & Sons Ltd on behalf of The Institute of Brewing & Distilling.

A simple method for measurement of the amylolytic activity of malt has been developed and fully evaluated. The method, termed the Maltose Value (MV) is an extension of previously reported work. Here, the MV method has been studied in detail and all aspects of the assay (sample grinding and extraction, starch hydrolysis, maltose hydrolysis and determination as glucose) have been optimised. The method is highly correlated with other dextrinising power methods. The MV method involves extraction of malt in 0.5% sodium chloride at 30°C for 20 minutes followed by filtration; incubation of an aliquot of the undiluted filtrate with starch solution (pH 4.6) at 30°C for 15 min; termination of reaction with sodium hydroxide solution; dilution of sample in an appropriate buffer; hydrolysis of maltose with a specific α-glucosidase; glucose determination and activity calculation. Unlike all subsequent reducing sugar methods, the maltose value method measures a defined reaction product, maltose, with no requirement to use equations to relate analytical values back to Lintner units. The maltose value method is the first viable method in 130 years that could effectively replace the 1886 Lintner method. © 2021 The Authors. Journal of the Institute of Brewing published by John Wiley & Sons Ltd on behalf of The Institute of Brewing & Distilling.

In this study, the major differences between commercial pale lager beers (PLB) and their non-alcoholic (NAB) counterparts were characterised by chemical-analytical and sensory analysis. Chemical-analytical profiling was performed using standard brewery analyses in addition to gas and liquid chromatography for quantifying volatile and non-volatile compounds. NAB differed in analytical composition from the PLB, in sugar, aroma, and amino acid profiles. Generally, the PLB contained higher levels of volatile aroma constituents (in particular, significantly higher levels of 2-methylbutan-1-ol, 3-methylbutan-1-ol, ethyl acetate, ethyl hexanoate and ethyl octanoate), specific amino acids (including cysteine, glutamine and alanine), sulphite, glycerol and proteins. NAB show significantly higher concentrations of fermentable sugars (maltose, glucose, fructose and maltotriose), as well as higher levels of amino acids (including threonine, serine and asparagine) and trans-2-nonenal. The PLB was similar in analytical composition, whereas the NAB could be discriminated into two clusters, reflecting different sugar profiles, reflecting the production technology. Organoleptic assessment described the flavour of the NAB as ‘worty’, ‘sweet’ and ‘watery’, while the PLB scored higher in ‘bitterness intensity’ and ‘fullness’. Interestingly, those NAB where the analytical profile differed the most from their PLB counterparts exhibited the largest differences in sensory properties. Furthermore, this study suggests synergistic and/or antagonistic effects between groups of chemical compounds which may explain the flavour differences. For instance, high sugar levels suppress the perception of bitterness, whereas sugars, aldehydes and esters impact on the worty flavour of NAB. © 2021 The Institute of Brewing & Distilling

Analytical and sensory profiles of non-alcoholic beers (NAB) vary on the process used for their production. The style and production procedure with blending and subsequent aroma enhancement lead to a wide range of product specific characteristics, which have so far only been evaluated using attributes and schemes developed for standard alcoholic beers. There has been no comparison and characterisation of wheat style NABs from different production processes using olfactrometry in combination with sensory analysis. GC-O/MS sniffing was performed to identify the aroma active components in wheat style NABs produced by different methods and the alcoholic standard beer to determine the differences in their aroma spectrum. Based on this, a sensory scheme for the targeted assessment of aroma profile, flavour intensity and attributes describing non-volatile properties was developed and validated using top fermented NABs. The odour activity of aroma substances differ depending on the matrix. The choice of attributes varies depending on the production process and aroma profiling is not always sufficient for the holistic characterisation of NABs. © 2021 The Authors. Journal of the Institute of Brewing published by John Wiley & Sons Ltd on behalf of The Institute of Brewing & Distilling.

Oak barrels serve two purposes in the production of distilled spirits: storage containers and reaction vessels. It is the latter function which bestows barrel aged spirits with their unique and highly sought after flavour profiles. However, achieving consistent flavour profiles between barrels is notoriously difficult as no two barrels are comprised of the same source of oak. Source variation is due to a range of factors, beginning with the genetic and topographical background of the oak tree from which the barrel staves originate, the spatial region of the tree from which the stave was taken and continuing through each step of the barrel production process. In this review, we detail each source of variation and highlight how this variation affects the reactants present in the barrel staves. The effect of pyrolysis on biomass is explored and how this knowledge relates to barrels that undergo the practices of toasting and charring is discussed. We also detail the significance of variation in the availability of reactants during the maturation process. The goal of writing this review is to identify areas of needed research, stimulate research and encourage investigation into the possibility of creating barrels with more consistent properties. © 2021 The Authors. Journal of the Institute of Brewing published by John Wiley & Sons Ltd on behalf of The Institute of Brewing & Distilling.

Nitrogen fertilisation at heading is a practice for increasing grain protein content in malting barley. The objective of this study was to assess the effects of fertilisation on grain protein, the content and composition of hordeins, and relationship to malt quality. In 25 field experiments in the Argentine Pampas, the effect of foliar nitrogen fertilisation at heading on the grain protein content was evaluated. In five experiments, the content and composition of hordeins and some malting quality indices was assessed. Nitrogen fertilisation at heading increased grain protein content, hordein content and the proportion of hordein C, and decreased the proportion of hordein B. In addition, malts obtained from the grains of the crops fertilised with nitrogen at heading had lower extract and higher hardness than those obtained without fertilisation. Malt extract was negatively associated with total hordein (or protein) content and positively with grain size. The inclusion of the fractions into which hordeins are classified did not improve the explanatory models for malt extract. Therefore, the composition of hordein does not seem to be a determining factor for malt extract when comparing samples with and without nitrogen fertilisation at heading. © 2021 The Institute of Brewing & Distilling

Although sorghum is widely cultivated in Africa, its utilisation for the production of lager type beer by breweries is relatively limited. Sorghum is used unmalted as a brewing adjunct, in limited quantities, with barley and commercial exogenous enzymes for lager type beer production. The use of sorghum malt as the sole raw material in brewing lager type beers is generally limited because of its low diastatic power and high tannin content among other factors. The objective of this study is to identify sorghum varieties that could be malted and used as the sole (100%) brewing material for lager beer production. Twenty-six sorghum varieties cultivated in Ghana were screened for malting and brewing potential based on germinative energy, green malt hydration, gelatinisation temperature, extract yield, limit attenuation, free amino nitrogen and diastatic power. Five of the varieties; Kadaga, Nakpaji, Kazea Nanga, Global 2000 and Kyere, of the twenty-six evaluated were found to have desirable characteristics for producing quality malt for lager beer production without the need for supplementary enzymes. Pilot scale malting and brewing trials are recommended to validate these findings.

This work reports the quantitative sensorial characterisation of Argentine ciders from the Patagonia and Cuyo regions. Argentine cider has been undervalued by consumers in recent years - a challenge to which the academic and manufacturing sectors have risen. Sensory analysis characterised 17 large scale (‘industrial') and one small scale (‘artisanal’) Argentine ciders. Some of the ciders had a fruity aroma with predominant apple notes, whereas others had unwanted sediment and sulphite odours. Based on the quantitative aroma results, the ciders were distinguished by principal components analysis (PCA) with two groups discriminated by the apple and sediment descriptors. The ciders were similarly characterised and distinguished by flavour. The work reported here can be used by cider producers to improve their products. © 2021 The Institute of Brewing & Distilling