Sugars and dextrins
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Sugar is the heart of any fermentation because sugar is the carbohydrate needed for yeast to produce alcohol.
Sugars in Wort and Beer
Fermentable sugars: glucose, sucrose, maltose, maltotriose production of alcohol & CO2 during fermentation. Non-fermentable dextrin (branched linkage starch residues) contributes to wort & beer viscosity and beer body (mouthfeel).[1][2]
Wort contains several types of sugars created during mashing:
- Glucose is the basic unit of sugar (monosaccharide), and is the first to be used by the yeast. There are also small amounts of sucrose and fructose present, which are very easily fermented as well.
- Maltose consists of two glucose molecules bonded together (disaccharide). It is the most common sugar and it is easily and rapidly fermented by beer yeast.
- Maltotriose consists of three glucose molecules bonded together (trisaccharide). This sugar is fermented by all beer yeast (to some extent), but not until all of the maltose has been fermented.[3]
- Dextrins (sometimes called alpha-glucans) are longer glucose chains that are typically not fermented, except by certain yeast strains.
Among the starch-derived sugars, only the monosaccharide (glucose) and the lineal disaccharide (maltose) are readily fermentable by S. cerevisiae, while the alpha-1,6-disaccharide (isomaltose) and the lineal trisaccharide (maltotriose) are only partially consumed. The lineal and branched oligosaccharides of higher degree of polymerization are not fermentable for this yeast. Fructose and saccharose, which are not starch sugars but are present in many starchy materials, are also good carbon sources for S. cerevisiae.[4]
Branched dextrins contribute to the body and mouthfeel of the finished beer but excessive levels will result in a poorly attenuated, high carbohydrate (high calorie) product.[5]
If the brewer expects to produce a beer with increased intensity of palate fullness or mouthfeel, relatively high levels of dextrins and limit dextrins would be required (52,75,76).[6].
Adjunct sugars
When brewing with added sugar or syrup, it is added to the wort kettle about 10 minutes before casting.[3] These sugar products do not need pre-treatment. Additional nutrient (or a protein rest) should be considered since the added sugar has no protein (nitrogen).
Liquid adjuncts are usually added to the brew at the wort boiling stage. The major sugars are glucose syrups, cane sugar syrups, and invert syrups. Although these syrups differ in detail, the essential similarity is that they are all largely concentrated fermentable solutions of carbohydrates. The term glucose can be misleading. Although glucose is the commonly used name for dextrose glucose syrups used in brewing, they are solutions of a large range of sugars and will contain, in varying proportions, depending upon the hydrolysis method employed, glucose (dextrose), maltose, maltotriose, maltotetraose, and larger dextrins.26[7]
A small amount of added sugar is not detrimental to beer taste because it is completely fermented.
- Sucrose - Pure cane sugar is perfectly acceptable, but partially purified preparations have been preferred because of their luscious flavors.[8]
Different colors of invert are available and although the darker ones are more highly colored than plain sugar they do not contribute a significant amount of flavor or color when compared to even modestly colored malt.[9]
Sugars are best used as late as possible in the brewhouse (i.e. at the end of the boil) to avoid losses and color/flavor pick up.[9]
Fructose accelerates oxidative processes, and therefore it should be added directly before fermentation. This avoids the negative impact during wort boiling.[10]
See Adjuncts.
References
- ↑ Holbrook CJ. Brewhouse operations. In: Smart C, ed. The Craft Brewing Handbook. Woodhead Publishing; 2019.
- ↑ Fox GP. Starch in brewing applications. In: Sjöö M, Nilsson L, eds. Starch in Food. 2nd ed. Woodhead Publishing; 2017:633–659.
- ↑ a b Kunze, Wolfgang. "3.2 Mashing." Technology Brewing & Malting. Edited by Olaf Hendel, 6th English Edition ed., VBL Berlin, 2019. pp. 219-265.
- ↑ 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.
- ↑ MacGregor AW, Bazin SL, Macri LJ, Babb JC. Modelling the contribution of alpha-amylase, beta-amylase and limit dextrinase to starch degradation during mashing. J Cereal Sci. 1999;29(2):161–169.
- ↑ Evans DE, Fox GP. Comparison of diastatic power enzyme release and persistence during modified Institute of Brewing 65°C and Congress programmed mashes. J Am Soc Brew Chem. 2017;75(4):302–311.
- ↑ Stewart GG. Adjuncts. In: Stewart GG, Russell I, Anstruther A, eds. Handbook of Brewing. 3rd ed. CRC Press; 2017.
- ↑ Briggs DE, Boulton CA, Brookes PA, Stevens R. Brewing Science and Practice. Woodhead Publishing Limited and CRC Press LLC; 2004.
- ↑ a b Howe S. Raw materials. In: Smart C, ed. The Craft Brewing Handbook. Woodhead Publishing; 2019.
- ↑ Kunz T, Brandt NO, Seewald T, Methner FJ. Carbohydrates addition during brewing – effects on oxidative processes and formation of specific ageing compounds. BrewingScience. 2015;68(7):78–92.