Editing Beer

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[[File:Beer.jpg|thumb|Beer is happiness]]
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Beer is the most widely consumed alcoholic beverage throughout the world and the third most popular drink after water and tea (Martínez et al., 2017a; Panda et al., 2015). Recently, craft or specialty beers are a growing segment in the beverage industry due to their emphasis on flavor.<ref name=baiper>Baigts-Allende DK, Perez-Alva A, Ramirez-Rodrigues MA, Palacios A, Ramirez-Rodrigues MM. [https://www.sciencedirect.com/science/article/abs/pii/S0889157521001216 A comparative study of polyphenolic and amino acid profiles of commercial fruit beers.] ''J Food Compos Anal.'' 2021;100:103921.</ref>

Based on the type of fermentation, beer can be divided into two broad types: ale and lager.<ref name=borsol>Boronat A, Soldevila-Domenech N, Rodríguez-Morató J, Martínez-Huélamo M, Lamuela-Raventós RM, de la Torre R. [https://www.mdpi.com/1420-3049/25/11/2582 Beer phenolic composition of simple phenols, prenylated flavonoids and alkylresorcinols.] ''Molecules.'' 2020;25(11):2582.</ref>

The composition of beer is very complex as it encompasses hundreds of small constituents, among which are volatiles, amino acids, salts, phenolics, hop resins and sugars, as well as macromolecules, including proteins, nucleic acids, and polysaccharides.<ref name=picariello>Picariello G, Mamone G, Nitride C, Ferranti P. [https://www.sciencedirect.com/science/article/pii/B9780128040072000230 Proteomic analysis of beer.] In: Colgrave ML, ed. ''Proteomics in Food Science.'' 2017:383–403.</ref>

Beer is a complex mixture of over 450 constituents and, in addition, it contains macromolecules such as proteins, nucleic acids, polysaccharides, and lipids.<ref name=steiner>Steiner E, Gastl M, Becker T. [https://www.researchgate.net/profile/Elisabeth_Wiesen/publication/226773564_Protein_changes_during_malting_and_brewing_with_focus_on_haze_and_foam_formation_A_review/links/56bc4bc508ae2481ab6aeeba.pdf Protein changes during malting and brewing with focus on haze and foam formation: a review.] ''Eur Food Res Technol.'' 2011;232:191–204.</ref>

The color is influenced by the grist materials as well as by all the processing steps in wort production with temperature impact ([[Maillard reaction|nonenzymic browning]] in [[decoction mash]]ing, wort [[boiling]]), as well as oxidation of [[phenolic compounds|polyphenols]] (in part enzymic). Turbidity changes the color.<ref name=pahl>Pahl R, Meyer B, Biurrun R. Wort and Wort Quality Parameters. In: Bamforth CW, ed. [[Library|''Brewing Materials and Processes: A Practical Approach to Beer Excellence.'']] Academic Press; 2016.</ref>

The use of exogenous [[enzymes]] has also allowed brewing beer for diabetics, or diet (low caloric) beers with a caloric-content reduction between 15% and 50%. Considering that in a typical beer residual dextrins account for 75% of the solids, diet beers are elaborated by reducing the remaining non-fermentable dextrins with the addition of exogenous enzymes, mainly glucoamylase.<ref name=guerra>Guerra NP, Torrado-Agrasar A, López-Macías C, et al. Use of Amylolytic Enzymes in Brewing. In: Preedy VR, ed. ''Beer in Health and Disease Prevention.'' Academic Press; 2009:113–126.</ref>

Wort dextrins have no flavor of their own and are not viscous enough in solution to account for the perceived (sensory) viscosity or 'body' of beer. However, they probably contribute some texture to the beer and the hydrolysis of these dextrins by salivary amylases in the oral cavity does yield glucose. This could easily contribute to the aftertaste of beer and perhaps a sense of richness. It is always wise to remember that no-one ever tasted beer as it exists in the bottle, but only as modified in the oral cavity-that is warmed up, degassed, changed in pH and diluted and reacted with saliva (!).<ref name=lewis>Lewis MJ, Young TW. ''Brewing.'' Springer; 2001:233–249.</ref>

Colder storage temperature greatly reduces the amount of oxidation after packaging.<ref name=lundm>Lund MN, Petersen MA, Andersen ML, Lunde C. [https://www.tandfonline.com/doi/abs/10.1094/ASBCJ-2015-0602-01 Effect of protease treatment during mashing on protein-derived thiol content and flavor stability of beer during storage.] ''J Am Soc Brew Chem.'' 2015;73(3):287–295.</ref> Samples stored at 22°C become more "autolysed meaty" during storage while samples stored at 35°C become more "fruity aged or vinous" and "overall stale". Furthermore, the control treated samples stored at 35°C become more papery over time.

Beer flavor is determined by its chemical composition, which includes proteins and volatile flavor compounds such as esters, alcohols, fatty acids, sulfur compounds and ketones. The stability of these chemical components determines the shelf life of packaged beer. As the exportation of beer continues to grow, flavor stability has become an important issue for breweries. However, the ubiquitous nature of beer ageing has made it a vexing problem. Various flavor characters were developed in aged beers. The commonly accepted one of them is the cardboard stale flavor which is not present in fresh and vintage (5-year-old) beers. Many factors are thought to be involved in beer ageing.<ref>Wu MJ, Clarke FM, Rogers PJ, et al. [https://www.mdpi.com/1422-0067/12/9/6089/pdf Identification of a protein with antioxidant activity that is important for the protection against beer ageing.] ''Int J Mol Sci.'' 2011;12(9):6089–6103.</ref>

Hydroxy fatty acids can be formed by photo-oxidation.<ref name=arts>Arts MJTJ, Grun C, De Jong RL, et al. [http://themodernbrewhouse.com/wp-content/uploads/2017/01/Oxidative-degradation-of-lipids-during-mashing..pdf Oxidative degradation of lipids during mashing.] ''J Agric Food Chem.'' 2007;55(17):7010–7014.</ref>

It is clearly understood that beer ages more slowly when stored cold.<ref name=golston>Golston AM. The impact of barley lipids on the brewing process and final beer quality: A mini-review. ''Tech Q Master Brew Assoc Am.'' 2021;58(1):43–51.</ref>

The shelf-life of beer is largely determined by its microbiological, colloidal, foam, and flavor stability.<ref>Zhao H. [https://www.sciencedirect.com/science/article/pii/B9780124046993000640 Chapter 64: Effects of processing stages on the profile of phenolic compounds in beer.] In: Preedy V, ed. ''Processing and Impact on Active Components in Food.'' Academic Press; 2015:533-539.</ref>

The flavoursome components of beer include bitter iso-α-acids and aromatic essential oils from hops, while esters, volatile fatty acids, sulphur-containing compounds, aldehydes and vicinal diketones originate from yeast (Leça et al. 2015; Bravi et al. 2017). Some phenolic acids are precursors of beer aromas, e.g. decarboxylation of ferulic acid during brewing leads to the formation of 4-vinylguaiacol, which has, even at the trace levels, an important impact on the beer aroma.<ref name=sibpla>Šibalić D, Planinić M, Jurić A, Bucić-Kojić A, Tišma M. [https://link.springer.com/article/10.1007/s11696-020-01276-1 Analysis of phenolic compounds in beer: from raw materials to the final product.] ''Chem Zvesti.'' 2021;75(1):67–76.</ref>

The colour of beer is one of the basic sensory attributes, being part of the beer’s style and of the given beer brand. It is related to the beer composition and the technical and technological conditions of brewing process (Mikysˇka and Psota 2019). The main components related to the colour of beer are components of malts and adjuncts which are modified during the malting process due to browning reactions and, in some time, further caramelization can take place during wort boiling.<ref name=ligdef>Liguori L, De Francesco G, Orilio P, Perretti G, Albanese D. [https://link.springer.com/article/10.1007/s13197-020-04740-8 Influence of malt composition on the quality of a top fermented beer.] ''J Food Sci Technol.'' 2021;58:2295–2303.</ref>

The bitterness is the most important hop-derived beer flavour attribute, which intensity is determined by the time and temperature of the wort boiling (Palmer 2006). Besides a-acids, other compounds contribute to the bitter taste: amino acids from the malt (e.g. L-tyrosine, L-tryptophan and L-leucine), dipeptides and cyclic diketopiperazines.<ref name=ligdef/>

The principal volatile compounds, identified in beer, were divided into 4 classes: higher alcohols, esters, carbonyl compounds such as aldehydes and ketones and sulphur-containing compounds. Ethanol gives off an alcoholic odour but also acts as a carrier of the other odour-active volatile compounds. The higher alcohols are produced by yeasts metabolism and impart a range of organoleptic attributes such as alcoholic, fruity, pungent, solvent-like and rose-like or floral, depending on the concentration and type of alcohol (Liu 2015) and they may be important because of their involvement in the production of esters (Cioch-Skoneczny et al. 2019).<ref name=ligdef/>

Apart from oxygen, the most dramatic impact on flavor stability of any parameter, on the route from barley to a beer in the customer’s hand, is the temperature of storage of the beer.<ref name=bamlen>Bamforth CW, Lentini A. The flavor instability of beer. In: Bamforth CW, ed. [[Library|''Beer: A Quality Perspective.'']] Academic Press; 2009:85–109.</ref> Any attempt to bring the temperature down post-packaging is highly advisable.

*https://www.sciencedirect.com/book/9780123738912/beer-in-health-and-disease-prevention
*Ragot, F., Guinard, J. X., Shoemaker, C., & Lewis, M. (1989). The contribution of dextrins to beer sensory properties part I. mouthfeel. Journal of the Institute of Brewing, 95, 427–430.
*[https://onlinelibrary.wiley.com/doi/10.1002/j.2050-0416.1989.tb04651.x The contribution of dextrins of beer sensory properties part II. Aftertaste]
*Rübsam, H., Gastl, M., & Becker, T. (2013b). Influence of the range of molecular weight distribution of beer components on the intensity of palate fullness. European Food Research and Technology, 236, 65–75.
*[https://onlinelibrary.wiley.com/doi/full/10.1002/jib.145 Wort composition and its impact on the flavour-active higher alcohol and ester formation of beer – a review]
*[https://www.researchgate.net/profile/David-Choi-2/publication/223197335_The_all-American_beer_A_case_of_inferior_standard_taste_prevailing/links/5ce324e7a6fdccc9ddc14195/The-all-American-beer-A-case-of-inferior-standard-taste-prevailing.pdf The all-American beer: A case of inferior standard (taste) prevailing?]
*[https://www.mdpi.com/1420-3049/24/8/1568 Beer molecules and its sensory and biological properties: A review.]
*[https://www.mbaa.com/publications/tq/tqPastIssues/2002/Abstracts/1121-01.htm Sensory and Analytical Characterization of Nonvolatile Taste-Active Compounds in Bottom-Fermented Beers]

==References==