THE CHEMISTRY OF FERMENTATION

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THE CHEMISTRY OF FERMENTATION

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What we will learn:

BASIC CHEMISTRY– ATOMS, CHEMICAL

BONDING, CHEMICAL EQUATIONS

CHEMICAL REACTION BASICS

WHY/HOW WATER IS SO IMPORTANT

pH

IONS

CARBOHYDRATES/PROTEINS/ENZYMES

MOLECULAR MOVEMENT

4 BASIC INGREDIENTS:

WATER - MALTED BARLEY - YEAST - HOPS

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Atom– simplest unit of

matter

ATOMIC STRUCTURE

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https://www.youtube.com/watch?v=BMIvWz-7GmU

ATOMIC STRUCTURE

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ATOMIC STRUCTURE

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H, N, C, O, Na, P, Ca, K, Mg

S, Cl, F, Zn, Cu, Fe, I, Hg, Br,

Pb

ATOMIC STRUCTURE

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IONIC BONDS & IONS

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COVALENT BONDS

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COVALENT BONDS - NON-POLAR MOLECULES/POLAR MOLECULES

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CHEMICAL BONDS AND ENERGY

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WATER – H2O

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WATER & HYDROGEN BONDS & IONS

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H2O: charged molecule which can bond to many molecules

WATER & HYDROGEN BONDS & IONS

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WATER & HYDROGEN BONDS & IONS

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HYDROGEN BONDS

1. Are moderately strong

intermolecular bonds; they

serve as links between

molecules.

2. Help determine three-

dimensional shape

3. Forms liquid water

4. Considerable cohesion

which creates a very high

surface tension

5. Formed between POLAR

molecules– most molecules

are POLAR

6. Helps hold many natural

molecules together

WATER & HYDROGEN BONDS & IONS

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HYDROGEN BONDS

-hold starch molecules together in barley seed: we break

them apart in the first part of the mashing/cooking process:

GELATINIZATION

WATER & HYDROGEN BONDS & IONS

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HYDROGEN BONDS

DNA

Enzymes/Proteins

Ex- H-bonds hold starch molecules together in barley

seed: we break them apart in the first part of the

mashing/cooking process

4 BASIC INGREDIENTS:

WATER - MALTED BARLEY - YEAST - HOPS

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WATER – THE UNIVERSAL SOLVENT

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H20: beer + life

1. Universal solvent

2. Necessary for all life’s

chemical reactions

3. Chemical reaction

medium for:

a. Fermentation

b. All living cells

(yeasts)

4. Stable temperatures for

life (high E storage in H-

bonds later)

5. High surface tension and

cohesion– “sticky”

Q- type of bond?

WATER – THE UNIVERSAL SOLVENT

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CHEMISTRYH20 and BREWING

1. Universal solvent-

MASHING (breaking down

large sugar to small simple

sugars)

2. Chemical reaction

medium for Fermentation

3. Stable temperatures –

lots of E for mashing,

boiling.

4. Cleaning

5. Heating & Cooling

WATER – THE UNIVERSAL SOLVENT

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Water for: CLEANING; HEATING and COOLING

Brewing LIQUOR-

mashing +

fermentation

WATER – THE UNIVERSAL SOLVENT

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H20 AND MIXTURES

1. SOLUTION

2. COLLOID

3. SUSPENSION

CHEMICAL REACTIONS: HOW TO READ THIS SHTUFF

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C6H1206 → C2H5O + CO2

C6H1206 + O2 → H2O + CO2

CHEMICAL REACTIONS

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CHEMISTRY2 MAJOR CHEMICAL RXN TYPES

1. Decomposition

2. Synthesis

*Energy and Chemical Rxns:

*Temperature and Chemical Rxns?

CHEMICAL REACTIONS

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CHEMISTRYLAWS OF THERMODYNAMICS

ACIDS AND BASES

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ACIDS AND BASES

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ACIDS AND BASES

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Pure Water is neutral (7.0 on the pH scale) : neither an acid nor a base

Base- a chemical above 7.0 on the pH scale

Alkaline is the adjective for base

Acid- a chemical below 7.0 on the pH scale

Acidic is the adjective for acid

ACIDS AND BASES

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The proper pH of solutions in the brewing process is vital for a quality product

For example in the Mashing Process, the mash should have a pH between 5.2 – 5.6

Improper pH can result in many problems, including the production of off-flavors,

which can ruin a batch of beer

ACIDS AND BASES

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pH buffer: A chemical of the opposite pH.

Example—the mashing pH is too alkaline (greater than 5.6),

so you can add an acid to bring the pH back down into range.

BREWING BUFFERS:

Bicarbonate—increases pH

Phosphoric acid—decreases pH

IONS AND BEER

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Ions: definition

Ions play important roles in living organisms, including yeasts.

They are important in overall health and chemical reactions the

organisms participate in.

Ions: electrolytes and salts

IONS AND BEER

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Calcium (Ca2+) and Magnesium (Mg2+) are vital for normal and happy yeasts

Sometime these ions need to be added to the brewing water for happy yeasts

IONS AND BEER

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Other Important Brewing Ions:

Ca+ -- Can also be used as an acidic buffer.

source: calcium chloride, calcium

carbonate, calcium sulfate

Na+ (sodium)– used as alkaline buffer

source: sodium bicarbonate

CO3- (Carbonate ion)– originates from CO2

from

yeast fermentation: can increase the pH

HCO3- (Bicarbonate ion)– also originates

from CO2 from yeast fermentation: can

increase the pH

Fe+ (Iron)– can be present in water from

pipes;

not good for brewing

IONS AND BEER

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Hard water contains high ion content, like

Ca+

and Mg+

Soft water is the opposite: low ion content

IONS AND BEER

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If water needs to be “adjusted” after

treating or purifying water, ions can be

added back for the best water for brewing.

Calcium sources:

Ca chloride hydrate

Ca dihydrate

Ca sulfate

Ca carbonate

(Ca levels for happy yeasts should be about

50ppm)

Magnesium source:

Mg sulfate (Epsom salts)

4 BASIC INGREDIENTS:

WATER - MALTED BARLEY - YEAST - HOPS

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CARBOHYDRATES

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Carbohydrates Primary Function:

ENERGY

We can get carbohydrates from fruits,

vegetables, pasta, cereal grains

Carbohydrates’ other function:

STRUCTURE

The most common structural

carbohydrate is cellulose.

Structural polysaccharides cannot be

broken down by most organisms for

energy

Structure for:

Seed hulls (coat) of cereal grains

Seed diagram

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CARBOHYDRATES

Energy carbohydrates come in 2

forms:

1. Simple sugars (monosaccharides

and disaccharides):

-glucose

-lactose

-sucrose

-fructose

Beer Fermentation ss:

-glucose (mono-)

-maltose (di-)

-maltotriose (tri-)

2. Complex sugars (polysaccharides):

-starch-- which is many glucose

molecules bonded together

-cellulose (seed hulls)

glucose

starch

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CARBOHYDRATES

Simple sugars that yeast can eat:

glucose

maltose

maltotriose

Simple sugar source: Conversion of

starch from barley grains by

mashing

Yeasts eat the simple sugars

from barley grains for ENERGY

and produce ethanol and

CO2 as by products.

yeast

barley

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CARBOHYDRATES

The starch is too large of a

molecule for yeasts to eat…so the

starch in the barley grain has to be

broken down into “chewable”

simple sugars for the yeast.

The starch is broken down into

simple sugars in the Mashing

Process

Cereal grains like barley, are

seeds.

Seeds contain 3 primary parts:

1. Seed coat or hull

2. Embryo- baby plant

3. Cotyledon- starch for

energy for the soon to be

growing plant.

yeast

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CARBOHYDRATES

glucose, maltose, maltotriosestarch

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CARBOHYDRATES

mashing

enzyme stimulation

Other carbohydrates

pertinent to brewing:

Dextrins: sugar molecules larger than

3 simple sugars—

not digestable by yeast;

can be left in beer for sweetness

and mouthfeel

Fructose: simple sugar found in

fruits—

typically not to be used in

brewing, as gives a cidery flavor

Beta glucam gum: larger

polysaccharide found in seed hulls.

More prevalent in rye and wheat.

Can thicken and gum up the

mash– not good.

Mashing process

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CARBOHYDRATES

What is Mashing?

Mashing is the process of turning the complex

carbohydrate—starch—of the malted barley, into simple

sugars—glucose, maltose, and maltotriose—that yeast can

eat to produce ethanol and carbon dioxide through

fermentation.

With the help of ENZYMES

Malted barley + hot water + enzymes simple sugars

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Proteins are vital to ALL LIVING THINGS / Proteins have many functions: BREWING

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PROTEINS

Proteins have many functions; 2 of which are:

1. Physical protection– like in seed hulls

2. Enzymes– vital for all chemical reactions in living things.

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PROTEINS

Proteins in beer are necessary for good beer foam (head)

…And healthy, happy yeasts

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PROTEINS

Too many proteins from grain hulls can cause hazy beer BREWING

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PROTEINS

ENZYMES:

• biological catalysts (speed up chemical reactions)

• vital for chemical reactions

• functions depend on their shape

• shape (therefore, function) can be disrupted by many things :

including improper Temperature and pH

Special shape of enzyme allows for chemical reaction to occur

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PROTEINS

Shape = Function

ENZYMES:

functions depend on their shape

shape (therefore, function) can be disrupted by many things :

including improper Temperature and pH

Disruption of protein/enzyme shape = DENATURING

this is why proper TEMPERATURE and pH are vital to good beer

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PROTEINS

Shape = Function

ENZYMES

Mashing enzymes:

alpha-amylase

beta-amylase

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PROTEINS

MOVEMENT OF MOLECULES

PASSIVE MOVEMENT

*Molecules move naturally ‘down’ gradients (Concentration, P, Electrochemical) WHY/HOW?

1. Simple Diffusion: movement of molecules DOWN a concentration

gradient

Ex: Adding water to distilled alcohol for proofing

Adding dye/stain to water

Adding a fruit puree to beer

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WHAT

INFLUENCES

PASSIVE

MOVEMENT?

2. Osmosis: diffusion of water across a semi-permeable membrane

MOVEMENT OF MOLECULES

ACTIVE MOVEMENT

Reverse Osmosis:

-Moving water (by pressure) from low concentration to higher

concentration; against the gradient.

-Pushing the “dirty” water across a membrane and leaving the

pollutants/minerals behind to have “clean” water.

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