Mashing - Mashing Mashing Mashing Mashing Conversion of...

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Unformatted text preview: Mashing Mashing Mashing Mashing Conversion of starch in milled grain & adjuncts to fermentable & nonfermentable sugars Composition of wort depends on the style of beer being produced Mashing chemical changes Acidulation (phytases), protein hydrolysis (proteases), starch hydrolysis (amylases) Acidification Acidification ACID REST responsible for lowering pH of mash for traditional decoction mashing of lagers Because of the trend of more modified malts, the acid rest is often eliminated Phytase is the enzyme that is responsible for acidification of the mash Hydrolyses phytin to phytic acid Acidification Acidification Phytase breaks down phytin into insoluble calcium and magnesium phosphates and phytic acid The process lowers the pH by removing the ion buffers and producing this weak acid Not used often as it may take 1­2 hours to reduce the pH to 5.0­5.5 range Acidification Acidification Optimal pH range for most beers is 5.1­ 5.6, lower end is better High mash pH can be corrected by adding acidified malts, dark roasted malts, salts, acids (phosphoric, lactic), lactobacillus culture Can acidify with phosphore, sulfuric (drier palate), hydrochloric, lactic (fuller palate) Acidification Acidification Biological acidification is common with German brewers (softer waters) Lactobacillus delbrueckii or L. amylolyticus Provides tang improves sharpness of flavor in German weizen beers Guinness: Part of the process is to blend in some specially soured Guinness. "...they have a series of huge oaken tuns dating back to the days before Arthur Guinness bought the brewery, which they still use as fermentors for a fraction of the beer. The tuns have an endemic population of Brettanomyces, lactic acid bacteria and Lord knows what else, and beer fermented in it sours emphatically. They pasteurize this and blend small quantities of it with beer fermented in more modern vessels." Proteolysis Proteolysis Reduces size of proteins, which can cause foam instability & haze, making smaller proteins, peptides, FAA Protein classification based on solubility (Osborne): Albumins (water) Globulins (dilute salt) Prolamines (alcohol soluble) Glutelins (dilute acid or base) Proteolysis Proteolysis Proteinase and peptidase are nonspecific names for amino acid peptide bond hydrolyzing enzymes Proteases hydrolyze proteins, albumins, globulins into medium sized proteins (peptones, peptides) Important for reducing haze Haze requires proteins and tannins but reduction in protein size will lower risk Proteolysis Proteolysis Medium sized proteins don't promote yeast growth but are useful for palate fullness, head formation & stability Protease activity optimum conditions 50­ 60 C and pH 4.2­5.3 Smaller peptides and FAA are used by yeast 45­53C and pH 4.2­5.3 Proteins Proteins FAA ­ peptides ­ polypeptides ­ proteins Proteases have specificity for amino acid bonds that they will cleave Have pH optimum, temperature optimum, etc Doughing In Doughing (95­113°F) is sometimes used by brewers for "Doughing In"­ mixing the grist with the water to allow time for the malt starches to soak up water and time for the enzymes to be distributed The use of a 20 minute rest at temperatures near 104°F (40°C) has been shown to be beneficial to improving the yield from all enzymatic malts. This step is considered optional but can improve the total yield by a couple ofpoints. Amylases Amylases Unfermentable starch converted to fermentable sugars Alpha amylase acts on insoluble and soluble starch, breaking starch down and creating more active sites for beta amylase Beta breaks maltose units off one at a time AMYLOSE β 1 234 nonreducing end β after α α α β reducing end αα α AMYLOPECTIN 1 2 34 Enzyme stops near α 1-6 links β after α α α α α α Amylases Amylases The enzymes stop at the alpha 1­6 bonds of amylopectin, leaving limit dextrins that add calories and body 60­80% of the carbohydrate can be converted to fermentables by alpha and beta combined There are a number of names for the enzyme that cleaves the alpha 1­6 bonds, pullanase, alpha 1­6 glucosidase, debranching enzyme, limit dextrinase Amylases Amylases Pullanase has optimal activity around 40 C Amyloglucosidase will hydrolyse the alpha 1­4 and the alpha 1­6 bonds http://byo.com/mrwizard/1089.html Alpha 72­75C pH 5.6­5.8 optimum Beta 60­65C pH 5.4­5.5 optimum, rapidly destroyed at 70C Tech. Q. Master. Brew. Assoc. Am., April/May/June 1977, 14(2), 105­110. The addition of starch debranching enzymes to mashing and fermentation and their influence on attenuation. Willox, I.C. and others Starch debranching enzymes (isoamylase, amyloglucosidase and pullulanase) were added individually and in conjunction with alpha and beta amylases to the mashing and fermentation stages of the brewing process. Their influence on attenuation is compared with some commercial enzyme preparations. The change brought about by these enzymes in the concentration of the mono, di and trisaccharide fractions in wort and in the package beer is given. Debranching enzymes do not survive kilning in large amounts Reingold labeled Forrest brewing Gablinger's Diet Beer 1967 (sexy name) because they weren't sure if it would damage their reputation Amyloglucosidase commercial 1964 Added debranching enzyme, resulted in lower residual carbohydrate and lower calories after dilution to constant abv Maltose-Dextrin Ratio Maltose-Dextrin Control of the alpha and beta amylases allows control of the amount of fermentable and residual carbohydrates Higher temperatures promote alpha at the expense of beta, so there will be more dextrins, less fermentables and less alcohol Long mash at 60­65 will result in a highly fermentable wort that will have a high attenuation limit Maltose-Dextrin Ratio Maltose-Dextrin Rest at 65 C for 10­15 minutes followed by an increase to 70 C will provide a medium bodied beer Lagers often mashed at 67­68 and dextrins are degraded slowly during lagering Short maturation process generally favors lower mash temp Control of Fermentable Extract Control Conversion temperature, rate and time of conversion Variation of 2­3 degrees for 5­10 minutes can dramatically alter the maltose­dextrin ratio Window of opportunity to make beer of wanted style is sometimes called "brewer's window" Stages of Starch Breakdown Stages Gelatinization (hydration), liquefaction, saccharification Gelatinization is a hydration of crystalline starch, increasing solubility and viscosity Gelatinization temperature is different for starches of different cereals Barley gelatinizes with alpha amylase 60­ 65C, rice at 80­85C Stages of Starch Breakdown Stages Rice or corn require separate boiling or hot flaking to gelatinize the starch Liquefaction via alpha amylase breaking long amylose chains down to shorter, rapid drop in viscosity Saccharification breakdown of dextrins to maltose Beta Glucans Beta Beta glucan hydrolysis enzymes most active around 35­40C They increase viscosity and may lead to slow lautering or increased chill haze problems Less soluble in cold beer ­­> contribute to chill haze Undermodified or unmalted barley contribute more BGs Factors Affecting Mashing Conditions Conditions Temperature Time Amber gold lagers rely on higher dextrins in higher mash temps, mild ales lower temp Longer times increase extract, but get smaller and smaller effect, time x temp for control pH pH optimum range 5.5­5.6, too low or high result in problems Factors Affecting Mashing Conditions Conditions Modification Ions Calcium, carbonate affect pH Water Quantity Well modified malts need lower temps (62­65C) well modified (65­68C) to make up for low beta Depends on type of mash Mash Thickness Thin mash favors conversion of starch to sugars but enzymes may be less stable MASHING SYSTEMS MASHING INFUSION Traditional mash schedule Maintain single conversion temp Simple, inexpensive, easily scaled Lower extract recovery, 3­10% less than decoction Requires greater precision on temperature Best done with well modified malts, no adjuncts MASHING SYSTEMS MASHING INFUSION Best with no protein rest 2­row less problems with protein (colloidal) related haze malt should have soluble nitrogen ratio S/T at least 38%, fine/coarse extract difference (FG­ CG) less than 1.8%, and be >95% mealy Bed of mash deeper than decoction, 1­1.2M in most craft breweries MASHING SYSTEMS MASHING INFUSION Mix grist with water to hit strike temp (63­ 65C), no protein breakdown, no BG breakdown Even wetting, no dough balls Mash off at 75­78C to deactivate enzymes, lower viscosity, wort removed from false bottom Spent grain sparged with hot water MASHING SYSTEMS MASHING STEP MASH Temperature controlled "step infusion" Series of rests at different temperatures Protein rest, sometimes acid rest Mimics traditional decoction in this regard, but is less satisfactory as none of the mash is boiled Can more easily control wort chemistry 4­5% increase in extract over infusion MASHING SYSTEMS MASHING STEP MASH Typically, 35 C acid rest, heated to 50C over 15­30 minutes for protein rest, raise temp over 30 minutes to 65­70C, hold 30 minutes for saccharification Can raise in slower steps, 60­66C then 67­ 70C, mashoff ~78 Slow rise with intermittant step at 55­60C favors maltose and highly fermentable wort 45C 15m ­ 60C 15m ­ 65C 10m ­ 75 C 5 m DECOCTION MASHING DECOCTION Traditional mash for poorly modified continental malts (Czec, German) Simplified temperature control before thermometers (volume measurement was simple) Excellent for undermodified or enzymatically poor malts 1, 2, or 3 steps DECOCTION MASHING DECOCTION Boiling decoction reduces complexity and solubilizes starch (heated through alpha amylase optimum on way to boiling) Thick mash promotes enzyme stability Boiling decreases problems with protein that would otherwise be expected in poorly modified malt Heat requirements are high and time is long DECOCTION MASHING DECOCTION Can have tannin problems if boil 6 row malts Triple decoction (acid, protein, saccharification rests) is being replaced with two or single decoction Three step decoction works better for wheat, bock, dopplebock, dunkles and marzens THREE STEP DECOCTION THREE Takes about 6 hours to get to lautering Variations in temps, times and heating speeds MASH IN Mix with cold water rest 15 min ACID REST Add hot water to get 35­40C When pH drops to 5.2­5.5, proceed ACID REST ­ FIRST DECOCTION One third of the mash (heaviest third) is removed, temperature raised to 65­70C, held there for 10­15 minutes, brought to boil for 10­ 45 minutes Breakdown protein, dissolve starch Add back to rest, mix and increase temperature to next rest Need greater volume in thin mash up to 40% PROTEIN REST ­ SECOND DECOCTION Temperature after mixing in boiled mash should increase to 50­55C Take 5­25 minute rest at this temperature and draw off next decoction Second decoction is again the heaviest third of the mash, temperature raised to 62­65C for 5­ 15 minutes, then raised slowly to 75C before boiling Boiled 5­25 minutes SACCHARIFICATION REST ­ THIRD DECOCTION Pump second decoction back and raise temperature to 65­68C Maintain temp for 15­30 minutes Mash continued until iodine test comes out negative IODINE TEST I2 intercalates soluble amylose helix producing purple color As amylose breaks down, purple color is lost, get reddish color then none MASH OFF Third decoction usually the lightest third and is boiled for 5­45 minutes Added back, temp raised to 75­77C Too high at this point may cause unboiled starch granules to burst, resulting in starch haze and tannin extraction TWO STEP DECOCTION TWO Only uses protein and saccharification rests Mashin at 50C, 20 min rest, remove heavy third, heat to 70C, rest, boil 20 minutes, return New temperature should be ~64C, 10 minute rest Remove third, heat to 71C, then boil 15m, return, mashoff 75­78 x 5 min SINGLE STEP DECOCTION SINGLE Only has saccharification rest, Sam Adams Mashin at 50C, 5 min rest Remove 33­45% of mash and heat to 66C, hold 10 mins, boil 5 mins Increases temp to 67­68 for saccharification, hold 15 mins Iodine test negative, heat to 77C transfer to lauter tun DOUBLE MASH (Infusion) DOUBLE Widely used with adjuncts Two separate mashes, cereal cooker used for non­flaked adjuncts Adjuncts boiled separately to gelatinize starch Again, flaked adjuncts are gelatinized during the flaking process Mash in barley with hot water in cereal cooker (10­20% of cereal used) DOUBLE MASH (Infusion) DOUBLE Raise temp to 45­50 for 15­30 minutes Add adjuncts, possible rest for saccharification before boiling may boil for 30­45 minutes for rice (as little as 5 for corn starch) Mashtun has mashin of barley at 38­50C Add boiled cereals to increase temp to 65­ 72C DOUBLE MASH (Infusion) DOUBLE Hold at saccharification temp for 30­40 minutes Raise temp to 75­77 for mashoff MASHING EQUIPMENT MASHING Mash tun, cereal cooker, separate lautering vessel Temperature control and decoction require a separate lautering tun Holding Hoppers (scale hoppers) weigh & dump grist Mash Tun in Britain and among craft brewers is used for mashing and lautering SS, sparge arm, false bottom MASHING EQUIPMENT MASHING Run until clear, return clowdy wort to mash tun Collect in brew kettle (gravity fed) Whirlpool is used to collect hops & hot break ...
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This note was uploaded on 09/19/2011 for the course FST 3124 at Virginia Tech.

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