Chemistry in Brewing- Beer

chemistry involved in beer brewing right from grain to glass

1. CHEMISTRY IN BREWING PRIYA. S ASST PROFESSOR FPT AMET Beer! This foamy, refreshing, sparkling alcoholic beverage conjures images of parties, festivals, sporting events, and generally fun stuff.

2. . Beer has been brewed since the ancient civilizations of Egypt and Mesopotamia. Beer is a very old drink discovered almost 5000 years back . Louis Pasteur also provided valuable knowledge which is still valid today, about fermentation and the essential requirements to make beer stable

3. The Art of Brewing

4. Water 92.9% Ethanol 3.9% Carbohydrates 2.5% Protein 0.2% Carbon dioxide 0.5% BEER COMPOSITION

5. BARLEY – the body & soul of beer YEAST – the life of beer HOPS – the spice of beer WATER – the integrity & purity of beer ADJUNCTS – Additive grains like rice or corn, fruit or spices What’s in Beer?

6. Malted Barley Two types of barley 2-rowed 6-rowed Provides fermentable sugars, flavor, and color. Malting process: Steeping Germination Kilning Purpose: Activate enzyme systems Preserve for brewhouse

7. COMPOSITION AND PROPERTIS OF BARLEY KERNEL Moisture content of barley 14 – 14.5% Barley must have a moisture content below 15% for long time storage. Total carbohydrates 70-85% Protein 10.5-11.5% Inorganic matter 2-4% Fat 1.5-2.0% Others 1-2%

8. STEEPING MALTING PROCESS Water uptake depends on the steeping time, temperature, kernel size, barley variety and the barley harvest year. Water content of the steeped barley is called the degree of steeping expressed in percentage. eg : for pale or Pilsner malt – water content 42-44% For dark malt – a water content of 44-47% Kernel size in mm Water content In % 2.9 43.7 2.8 43.3 2.5 43.6 2.2 48.9 2.0 49.0

9. GERMINATION PROCESS DURING GERMINATION Growth processes Enzyme formation Metabolic changes

10. Growth process Rootlets- longer and warmer the germination the longer the roots become and so the greater the loss acrospire - important feature for differentiating from barley, the length of the acrospire is relate to the progress of the metabolic changes inside the kernel acrospire exceeds the length of the kernel it is said to be overgrown

11. Enzyme formation Abundant in barley They are increased during the time of germination - starch degrading enzymes α and β amylases. Cytolytic enzymes β glucanases and cytase

12. kilning Water is removed from the green malt. The malt then become stable and storable. Changes during kilning The water content is lowered Germination and modidfication are stopped Color and flavour compounds are formed

13. DMS Formation during germination and kilning A volatile sulphur compound gives beer a flavour referred to as cabbagey or cooked vegetable The higher th kilning temperature more DMS-P is converted into DMS. The flavour threshold of DMS is considered to be 50-60 μ g/l

14. HOPS – the spice of beer Germany is the largest producer. Humulus lupulus (dioecious) only female plant is used in brewery because they contain bitter resins ethereal oils which supply bittering and aroma components to beer. -Used as: Whole cones Pellets Extracts Lupulin glands Hop cone Isomerized hops are used because it keeps the quality of the beer unchanged for 2 years

15. Alpha Acid Isomerization humulone isohumulone

16. Cont … MICROBIAL STABILIZATION hops have antiseptic qualities HOP AROMA fruity flowery characteristics BITTERNESS balances malt sweetness FOAM STABILIZATION enhances head properties There are two primary hop styles: Aroma Hops – Saaz , Fuggle & Hallertua Bitter Hops – Brewer’s Gold & Unique Hops contain 14-21% hop resin Hops contain 0.5 – 1.5% hop oil. Oils are fromed in the lupulin glands and give hops a characteristic aroma. Hop oil is not a single compound. It contains about 200 cmpounds .

17. Water – “Integrity & Purity” Water usage in a brewery is substantial and varies between 3.7-10.9 hl of water per hl of sales beer, on average it is 6hl water makes up 92% of beer through filtration or boiling; impurities, aromas & flavor differences can be mitigated Water treatment depends on Removal of suspended matter Removal of dissolved materials Removal of microorganisms

18. Yeast – “Life of Beer” Unicellular microorganisms- S acchomyces cerevisiae produces carbon dioxide and alcohol Two types of yeast are used to produce beer: ALE – top fermenting LAGER – bottom fermenting

19. Lager ale

20. Adjuncts Unmalted cereal which is cheaper is referred to as adjunct. Maize, maize grits, maize flakes, corn syrup, broken rice, wheat, barley, caramel, sugar(crystalline sugar) adjuncts are added to change the flavor, character or profile of beer. used to supplement main starch source to provide better foam retention, color or aroma

21. Brewhouse Fermentation Lagering Starch Sugars Ethanol Sugars Carbonation Flavor maturation Wort production Flavor production The brewing process

22. PROCEDURE FOR BREWING BEER

23. mashing Most important proces in wort production. Grist and water are mashed and the contents of the malt are brought into soultion and extract is obtained. The degradation process includes 1.starch degradation . 2. β glucan degradation 3. protein degradation Starch degradation occurs in 3 stages 1. gelatinisation 2. liquefaction . 3. saccharification Gelatinisation varies fro each type of cereal malt & barley starch gelatinise in the presence of amylases at 60°C and rice starch at 80-85 °C pH of the mash should be 5.4-5.6

24. Break down carbohydrates into fermentable sugars Break down proteins into usable amino acids Choose temperature range where different enzymes are highly active for various processes Amylases (α and β) can only break down 1,4 linkages

25. α amylase breaks down the long starch to smaller dextrins at 72-75°C and destroys at 80°C. pH -5.6-5.8 β amylase splits maltose of from the non reducing ends of chains but it also produces glucose and maltotriose Acts optimally at 60-65°C and sensitive at higher temperatures . pH- 5.4-5.5 Starch breakdown should be monitored because residues of undegraded starch and larger dextrins cause starch hazes in beer

26. L autering Filtration process in which spent grains play the role of the filter material The extract retained is washed by hot water – sparging . The wort draining off from the spent grains is called the first wort (4-6%more extract should be in beer) The thinner wort running off is called second wort . α amylase destroys at 80°C so the temperature is maintained during lautering

27. Brew kettle -. 1.Extraction and transformation of hop components. 2. Evaporation of water. 3. Wort sterilization. 3. Destruction of all enzymes. 4. Increased coloration of the wort 5. Acidification of the wort 6. Formation of reducing substances 7. Effects on the DMS content of the wort . Wort boiling operations

28. The zinc content of the wort Important trace element in wort is zinc atleast 0.10-0.15 mg/l Zinc assists protein synthesis in yeast cells and controls their nucleic acid and carbohydrate metabolism. Zinc deficiency causes fermentation problems. Foam stability is worse when zinc is deficent . Wort should be boiled in copper vessels because copper vessels always contain a small amount of admixed zinc. Zinc chloride is added when stainless steel is used for wort boiling since stainless steel don’t contain zinc.

29. The chemistry of wort boiling turning-point in the brewing of beers Boiled for 1-2 hours Boiling results in the formation of melanoidins and oxidation of polyphenols Hop resins , hop oils and hop polyphenols –important components of hops in beer production Hop resins- bitter taste to the beer Hop oil- volatile during boiling, its added at the end of boiling i.e., 15-20 mins before casting Hop polyphenols- water soluble , includes anthocyanogens , tannins and catechins Polyphenols – palate-fullness and bitterness of beer

30. The changes that occur during boiling 1.Dispersion of hop resins and oils 2. Isomerization of some α acids 3.Conversion of DMSP To DMS. 4. Formation of new flavour and aroma –through maillard reactions 5.The denaturation and inactivation of residual enzymes 6. The denaturation and coagulation of protein which alter the foam stability Over heating the wort causes caramelization of the wort sugars which causes unwanted flavours Hot wort is clarified because they contain suspended particles Removed – whirlpool Collected as – trub Clarified wort passed through plate heat exchanger. It is necessary to cool the wort 5-6°C. during this process clear wort become turbid because of the formation of cold break. Wort is cooled Wort is aerated – enables yeast growth .

31. Fermentation Uses single strand of yeast-Saccharomyces cereviaciae Follows Emden- Meyerhoff - Parnas pathway (glycolysis ) ending in ethanol Must Avoid bacterial / wild yeast infection Requires steady temperature

32. EMP Pathway(glycolytic pathway) ATP ADP Hexokinase Phosphoglucose isomerase ATP ADP Fructose Bisphosphate aldolase +

33. Glycolysis Triosephosphate isomerase Glyceraldehyde phosphate dehydrogenase NAD + NADH NAD + NADH ADP ATP ADP ATP Phosphoglycerate mutase H 2 O H 2 O Enolase

34. Formation of Ethanol ADP ATP Pyruvate kinase CO 2 NADH NAD + Typical concentrations of ethanol formed: 40 to 60 g/L

35. Growth phase of yeast Lag phase- cell mobilize actively Exponential phase or log phase- the cells divide at a constant rate Stationary phase- the growth rate remains constant. Death phase

36. Fermentation by-products have a great effect on beer. Contribute to the full-bodied tast of the beer Effect on aroma and foam stability Fermentation by-products Diacetyl Higher alcohols Esters Aldehydes Sulphur compounds

37. Yeast metabolism during fermentation

38. Flavour-aroma wheel for beer

39. Green beer aroma substances Diacetyl , sulphur compounds, aldehydes They give beer an unclean,immature , unripe, unbalanced taste, and impair beer quality Mature beer aroma substances Higher alcohols esters, They determine the aroma of beer In contrast to the green beer aroma compounds, they cannot be removed again from the beer by normal brewing process

40. Higher alcohols Formed by the decarboxylation and reduction of a - keto acids. From amino acid anabolism and catabolism.

41. esters Closely linked to lipid metabolism - growth. Reaction of an alcohol and fatty acid intermediate

42. Vicinal Diketones ( Diacetyl ) Buttery, butterscotch flavor

43. Beer treatment Carbonation Flavour/aroma changes Additions of colouring and flavouring materials Stabilization against non-biological haze Clarification Biological stabilization

44. Taste Perception Bitterness* - on the back of the tongue Sweetness - on the tip Sourness* - on the sides of the tongue Saltiness - just to rear and sides of tip

45. Taste Bitterness - Hops, Tannins, Malt, Minerals Sweetness- Malt, Hops, Esters, Diacetyl Sourness- Carbonation, Contamination Saltiness - Minerals

46. Touch and Feel Texture - creamy, over/under carbonated Body - full bodied or thin... Astringency - Dry, puckery feeling (Not really a flavor) Others - Oily, menthol-like, burning, etc

47. Beer quality Flavour-taste and aroma Alcoholic content-food value Color Head retention Clarity- absence of haze Absence of gushing

48. Thank you!