50373692 8 Bakey Technology

7/29/2019 50373692 8 Bakey Technology

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Dr. Li Wenzhao

Department of Food Science and

Engineering

Bakery Technology


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1 History Bread being one of the earliest

processed food

Manufacturing industry from 3,000B.C.E. in Egypt

$16 billion industry in the US

Wheat consumption ~100 Kg/person/year

a central ago, 50 Kg 1960s, 70 Kg 1980s,

2000 65 Kg

European as high as 140 Kg/person/year


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BreadsLeavened

Flatbread (unleavened)Labeling

Wheat bread = white flour Whole wheat = whole grain

Multigrain, cracked wheat, or 7-grain may not be whole grain


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Leavened Breads


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Unleavened Breads


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Oats, barley, and some foodproducts made from cereal grains


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A wheat field in Dorest, England

Wheat

Planting


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2 Wheat morphology and chemistry

Section of a grain of wheat


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a Kernel of Wheat

83% of kernel isendosperm

14.5% of kernel is Bran

2.5% of kernel is Germ


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1) Bran Layer

14% of kernel

Several thin layer Contains aleurone layer

viable, protected layer,

surrounds endosperm

enzyme activity

Contains: protein, lipid,

minerals, vitamins, phenolic

compounds, cellulose

Graphic: http://www.generalmills.com/wholegrain/101/


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Source: Hoseney, R.C. Principles of Cereal Science and Technology, 2nd Edition, pg. 17.


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2) Starchy Endosperm 83% of kernel

Non-viable, but may haveenzymatic activity

Contains high levels of starch

75% of wheat endosperm source of fermentable sugars

Contains extensible gluten

proteins Very little mineral, fiber, fat &vitamins



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3) Germ 2-3% of kernel Viable tissue

Contains embryo all rudimentary growth

tissues

Responsible forgermination e.g. during malting of barley

Contains higher quantitiesof lipid than otherfractions



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3 Milling of Wheat

Flowchart ofwheat milling


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Wheat Mill Fractions

Wheat Flour Germ Bran

Protein 12.0 11.0 30.0 14.5

Ash 1.8 .4 4.0 6.0

Fiber 2.5 - 2.0 10.0Fat 2.9 .88 10.0 3.3


Milling is a process which attempts to cleanly separate the

anatomical parts of the grain to produce a product (flour), which

is chemically, compositionally, and functionally very different.


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FlourFlour

All-purpose flour

Cake flour Instant/quick-mixing flour

Self-rising flour

Whole wheat flour


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All-purpose flour

Milled and sifted blend of different varietiesof wheat.

Made primarily of endosperm

Can be bleached or unbleached: nonutritional difference between the two

General baking and cooking


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Cake Flour Made from a class of wheat called soft

wheat.

Used for making cakes and other bakedproducts with delicate textures.


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Instant or quick-mixing flour All-purpose flour that has been specially

treated to blend easily with liquids.

Used to make gravies and sauces.


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Self-rising flour Is an all-purpose flour with added

leavening agents and salt.


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Whole Wheat Flour

Made by milling the entire wheat kernelso it contains the bran, germ, and

endosperm.

Gives baked products a nutlike flavor and

coarser texture than does all-purposeflour.


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4 Wheat protein and starch Flour composition critical for the

fermentation and physical structure ofthe dough and finished bread

Refined white flour used mostly in US,from endosperm portion

Consists mainly protein and starchSmall portion of hemicellulose and lipid


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Wheat Protein

8%-15% of wheat flour is protein

High protein flours from hard wheat

best for bread, >11% Low-protein flours from soft wheat


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Wheat Protein

Gliadin and glutenin the most

important ones, ~85%

When hydrated and mixed, form

gluten, key component of bread

Remaining globulins and albumins,- and -amylases


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Gluten Gluten consists of two protein

-Glutenin and

-Gliadin

They interact with each other by thekneading of a wet dough, to form a

protein complex Gluten is a highly elastic material


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Gluten

Protein complex gives bread

structure and elasticity and essential

doe the leavening process

Poorly formed or absent in non-wheat flours

Most commercial breads containsome wheat


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Benefits of Vital Gluten Instant protein source

Aids in water absorption, 1% added

increases dough absorption by 1.2% Benefits should include volume increases,

and increased processing tolerance for

bread and rolls Usage:

Whole grain breads:2-5%

High fiber, reduced calorie breads 5-12%

Pizza dough:0.5-1%


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Wheat Carbohydrate

75% of the total weightLargely compose of starch

Some other carbohydrates

A small amount of simple sugar,

cellulose, fiber (~1%)


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Wheat Starch Native starch granule insoluble

Amylose and amylopectin withinspherical granules in rigid, semi-

crystalline network Milling can damage a small

percentage, increase waterabsorption and enzyme exposure


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Starch StructureNatural Starch conformation

Mixture of amylose and amylopectin

Pure amylose not natural (only 85%)Waxy maize starch - amylopectin


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Starch CompositionTYPE OF

STARCH

AMYLOSE % AMYLOPECTIN

%

MAIZE 26 74

WHEAT 25 75

RICE 17 83

POTATO 21 79

CASSAVA 17 83

WAXY MAIZE 1 90

HIGH AMYLOSE 70 30


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Starch ConfigurationConfiguration = 3D structure

Not soluble in cold water

Settles

No adhesive powerNo binding capacity


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Starch ConfigurationTo have the previous properties the starch

slurry must be heated


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Amylose vs. Amylopectin

Starch is a food storage polysaccharide used byplants to organize glucose polymers

Two unique patterns of linear organization:AMYLOPECTIN (75%) AMYLOSE (25%)


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Amylose vs. Amylopectin Starch linear structural pattern confers

unique tertiary structure

AMYLOPECTIN (75%) AMYLOSE (25%)


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Amylose vs. Amylopectin

Literature suggests that amylopectin is morereadily digested by -amylase

Genetically modified maize, rice and barleycontaining 100% amylopectin starch aredigested faster than normal counterparts (Nodaet al. 2002)

Resistant starches (low GI starches) exhibitslow release of glucose into intestinal lumen,non-resistant starches (high GI starches) exhibit

rapid release of glucose into lumen (Bird et al.2007)

Resistant starches high amylose content

Non-resistant starches high amylopectin content

St h G l i P t i


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Starch Granules in Protein

Matrix



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Starch Granules andGelatinization

In the storage areas of plant (seeds, roots),molecules of starch are deposited as tiny,organized unit granules

In cold water, starch granule is insoluble. In warm water, gelatinization

- swelling of granule as water is absorbed

- disruption of the granule structure

- loss birefringence

Starch Granules &


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Starch Granules &

Birefringence

Bright field microscopy Polarizingmicroscopy

Gelatinizatio

n

(h

eat+water)


S h G l P l h Di ib i


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Wheat endosperms consist of three

distinct starch granules (Raeker et al.,

1998) A-granules: large, disc shaped

B-granules: small, spherical shape

C-granules: not well defined

Starch Granule Polymorph Distribution


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Riffkin et al. (1990) and Brosnan et al. (1999)

Contributary role of starch granule size distribution toethanol yield

Starch Granule Polymorph Distribution

A vs. B-granule

Structural Distinctions Amylose content

Lipid content

Size

Crystallinity


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Starch GelatinizationGelatinization only occurs with heat and water

Dry heating = dextrinization


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Starch Gelatinization5% Corn starch = start of heating only has

water absorbed onto granule surfacesGranules still clumping


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Starch GelatinizationAt 40oC more water as absorbed and granules

start to separate


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Starch GelatinizationAt 65oC more water as absorbed and granules

start to rupture


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Starch GelatinizationAt 70oC further rupture, leakage


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Starch Gelatinization


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Starch Gelatinization


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Factors AffectingGelatinization

Main determinants of gelatinization:

Water content

Starch concentration

Nature of starch

Degrading enzymesOther environmental factors


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Factors AffectingGelatinization

Main determinants of gelatinization:

Fat

Protein

Temperature

Hydrogen bonds


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Staling

Usually ascribed to :

Loss of moisture

Retrogradation


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Staling Bread and buns become firm (high-moisture,

yeast-raised products);

Crusty loaves dry out;

Crisp baked goods go soft (low-moistureproducts);

Off-flavours develop.


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Staling 1 to 5% of baked goods are lost

Climate plays a role

Storage conditions


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StalingMostly ascribed to:

Retrogradation

Moisture exclusion (crystallinity)

Brittle crumb

Low temperature speeds up the

process

Freezing prevents staling

5 Bread Unit Operations


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p

Modern Bread Technology Straight dough process

Homemade, one-batch-at-a-time, not much by the

baking industry Sponge and dough process

Mostly used, using partially concentrated portion

of dough-sponge to ferment, and then mixing withthe remaining ingredients

Liquid sponge process

Continuous bread-making, liquid sponge, savelabor and time, using thin, quality not as good

Chorleywood Process

General Manufacturing


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General Manufacturing

Principles

W ei g h an d m i xi ng red i en t s d o u g h F e rmen tedd o u g h

Por t i onedan d

shapedb ak e Coo l

sl i ce p ack

fermentation

fermentation


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Formulation Flour- Usually all purpose flour used forbaking breads. Main function is to give

structure to the bread. Leavening Agents- Produce gas in

batters that make baked products rise.

Steam: high temperatures used in baking heatliquid ingredients enough to form steam.

Yeast Baking soda and powder

Formulation


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Formulation Liquids- Water, milk, and juice are

common. They serve to hydrate starch to

absorb water. Fats- Tenderizes the product.

Eggs- Add color, flavor, and contribute tostructure.

Salt and sugar- Adds flavor and

regulates the action of yeast.


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Typical recipies

161,200 kg165,700 kg158,200 kgtotal

2,500 kg4,000 kg1,000 kgImprover

1,700 kg1,700 kg1,700 kgSalt

2,500 kg5,000 kg2,500 kgYeast

55,000 kg55,000 kg53,000 kgWater

100,000 kg100,000 kg100,000 kgFlour

BaguettesBread rollPlain white

bread


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Typical recipies

189,700 kgTotal172,700 kgTotal

15,000 kgImprover

10,000 kgRaisins1,500 kgImprover

2,000 kgSugar2,500 kgOlive oil

1,7000 kgSalt1,700 kgSalt

8,000 kgYeast1,000 kgYeast

53,000 kgWater66,000 kgWater

100,000 kgFlour100,000 kgFlour

Raisin breadCiabatta

Mixing


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Mixing

Dough Formation

Doughs are viscoelastic (flows andrecoils)

Structure largely from proteins calledglutens

consist of gliadins and glutenins

30% of amino acid residues arehydrophobic

water insoluble; can bind water

Kneading


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Kneading

Kneading bread subjects it to shearforces

promote interactions between gluteninmolecules

H- bonding, hydrophobic interactions, S-Sbonds

creates elastic protein networks (films)

which trap gasviscosity enhanced by gliadins and starch

molecules

Kneading is important


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Kneading is important

After forming the dough for yeast breads,

you MUST knead it!!!! Almost all of the gluten forms during the

kneading stage. It is important to not add

too much extra flour while kneading. Thiswill make the dough far too stiff.


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Dough Formation Knead to optimum rheology optimumdough strength

over-kneading breaks protein structure

before kneading after optimal kneading

50 m 1 m

Temperature control is very


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important

Fermentation rate will change in function ofthe temperature : in the same time more (orless) CO2 will produced. If the bread is 10% bigger you need also 10 % more trucks.

Relationship between humidity and

temperature : or the dough will get sticky orcrusty in the proofer


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Dough consistency will change in function of thetemperature i.e. the behaviour on the line will bedifferent

During lamination the butter or margarine will getcolder or warmer in line with the doughtemperature. To make good puff both should

have the same consistency

In 1 hour in 1 kg dough of 28C the yeast will

metabolise about 10 g of sugar. If the doughhas 29C, the yeast will metabolise 10 % moresugar. Result the bread is less sweet.

Mixing


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Mixing

Temperature control can happen indifferent ways :

Adding ice to the dough

Use cold water Cooling the mixing bowl

Use salt as a saturated solution

Cool down flour during pneumatic transportwith CO2 (and not injecting CO2 in the dough)

Bread Fermentation


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After you knead the dough, what do youdo???

When you let it rest in a warm place, theyeast acts upon the sugar and the carbondioxide causes the bread to rise. This iscalled FERMENTATION!

The bread should at least double in sizeduring fermentation

The fermentation occurs during bread manufacturing

is different from most other food fermentations Purpose

Fermentation end products


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About Yeast Single celled, microscopic plant.

When you add sugar to yeast, it reacts to thebacteria and creates carbon dioxide. Thisleavens the baked product.

Water mixed with yeast MUST be between 110and 125 degrees in order to keep the yeast alive.

Available in three forms:

Active dry (what we use)- Compressed( very perishable)

- Fast rising yeast (rises twice as fast)

Types of Yeast


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yp Commercially available

Yeast cream

Used directly, highly perishable Yeast cake

Yeast cream through filtration press or vac. filter

Refrigeration required, shelflife a few week Metabolically active, quick fermentation

Dry active yeast

Home bread making, small business operation Last 6 months or longer

Require hydration, not as active


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S. cerevisiae, or bakersyeast Properties and characteristics for bread

making

Gassing power

Flavor development

Stable to drying Stable during storage

Easy to dispense

Ethanol

cryotolerant

Yeast Cultures


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Growth medium Molasses or another inexpensive source of sugar and

various ammonium salts

Other yeast nutrients Ammonium phosphate Magnesium sulfate Calcium sulfate, trace minerals (zinc, iron)

Cell mass production required conditions O2 level Temp (30C)

pH (4.0-5.0) continuous

Fermentation


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Fermentation

Lag phase usually

Bakersyeast facultative metabolism Aerobic (via TCA cycle)

Anaerobic glycolytic fermentation pathway

Glucose inhibit TCA enzymes

CO2

Sugar metabolism by bakers yeast


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g y y

Carbohydrate sources Starch

Sugars (glucose and maltose) Transport and utilization

Sequential use Regulation-glucose represses enzymes involved in

maltose transportation

Maltose represses invertase expression

Mutants available Sugar transport

Glycolysis

Fermentation


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End products

CO2

Other compounds Various acids and organic compound by yeasts

By LAB

Flavor and rheology of the dough

Factors affecting growth

Temp-hold at 25-28 instead of the optimalgrowth temp 36-39 to minimize microbailcontamination, and maintain yeast activity

Relative humidity 70-80%

Glucose


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Glucose 6-phosphate

Fructose 6-phosphate

Fructose 1, 6 phosphate

DGAPDihydroxyacetone

PGALGlyceraldehyde

3-phosphate

PEP

Phosphenopyruvate

Pyruvate

Oxaloacetate

Respiration Chain

TCA Cycle

CO2

CO2Lactic acid Acetyl CoA

+36 ATP

Ethanol

CO2+2 ATP

+2 ATP

Factors affecting fermentation


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g

Too much salt inhibits yeast activity, reducing

the amount of carbon dioxide gas producedand decreasing the volume of the loaf.

No salt Normal salt Double salt


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Punching Down! When the dough has risen all

the way and has doubled insize, you have to punch it

down to release some of the

carbon dioxide. Some dough requires a

second rising period.


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Avoid Over fermentation

Gluen streches, becomes weak andcan collapse

Coarse grain & sour odor due toexcess acid production

Less color in baked crust


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Oven spring The quick expansion of dough during the

first ten minutes of baking, caused byexpanding gases.

Baking


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30 C1.CO2-gas expands

2.increased enzymatic activity3.reduced solubility of CO2 in water

45 50 C1.yeast dies

50 60C

1.intensive enzymatic activity2.starch begins to gelatinise

Baking


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Types of ovens

1. According to heating system directly fired

indirectly fired (air, oil)

2. According to product movement static ovens

continuous belt ovens (tunnel ovens) rotary ovens (horizontal & vertical)


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Types of ovens

3. According to type of fuel

gas

gasoil

4. According to heard type

stone metal (including baking trays)

Cooling & Freezing


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Don't touch the bread as long as the crumb hasmore then 80C (semi liquid damage of

structure staling)

During cooling and freezing bread looses about

2 % of its weight (i.e. water loss)

Freezing : only water freezes. Because of the

difference in moisture content between the crustand the crumb, the crust can flake off.


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Cooling & Freezing


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In the case of frozen dough, special attention hasto be paid to :

1.Freshness of the yeast, type of yeast (freezetolerant), quantity of the yeast (more but toomuch can be negative weakening ofgluten structure).

2.Avoid that fermentation starts beforefreezing (unless you make preproofed frozen

of course)3.Handling in the shop : slow thawing to get

even temperature distribution in the product

before proofing and baking (retarder-proofer)

Cooling & Freezing


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During storage at - 18C theproduct looses moisture and

becomes drier and drier(flaking).

This depends on the storageconditions (air velocity,temperature fluctuations and

relative humidity in thefreezer) = freeze burn

Understanding how bread rises


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When yeast (block or dried) is mixed with waterand sugar it becomes frothy.

The yeast cells multiply, this process is calledfermentation. Fermentation stops if the

water/dough is too hot or cold or if there is nosugar.

Yeast mixture or dried yeast is added to flour,t d th i di t k d d d


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The loaf tin is put in the oven, the heat killsthe yeast and cooks the dough leavening a'risen' loaf.

Carbon dioxide gas is produced by the yeastwithin the dough forming pockets whichmakes the dough rise in the warmth. Thisprocess is called proving.

water and other ingredients, kneaded andplaced in a loaf tin.

6 Bakery prodcut technology

l


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examples

Sour dough Bread

Bread product

Breakfast Foods

Example1- Sour dough Bread

Sour dough rye bread


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Sour dough rye bread Most studied bacterial bread fermentation

Popular in Europe

Micro-organisms isolated from sour rye Bacteria: Lb. plantarum, Lb. brevis, Lb. casei, Lb.

fermenti, Lb. pastorianus, Lb. buchneri, Lb.leichmannii, Lb. acidophilus, Lb. farciminis, Lb.alimentarius, Lb. vrevis var. lindneri, Lb.fermentum, Lb. fructivarans, Pediococcusacidilactici

LAB with very high amino acid requirementdominant

Yeasts: Candida krusei, Saccharomycescerevisiae, Pichia saitoi, Torulopsis holmii

Candida kruseidominant

Sour Dough Bread


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The San Francisco sourdough Frenchbread

Use start culture ormother-sponge Occurred in San Francisco, continuously used

for over 140 years

Ecosystem consists of on species of yeastand one species of bacteria

Occurred in a ratio of 1:100

Yeast- Candida milleri(or Torulopsis holmii)

Bacteria- Lb. sanfrancisco

Formulations for San Francisco Sour Dough

French Bread


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French Bread

Starter-sponge Bread dough

100 parts of previous sponge 20 parts starter-sponge

(40% of final mix) (11% of final mix)

100 parts flour (high-gluten) 100 parts flour (regular patent)

46-52 parts water 60 parts water

2 parts salt

Starting pH 4.4-4.5 Starting pH 5.2-5.3

Final pH 3.8-3.9 Final pH 3.9-4.0

Example2 Bread product


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Flour arrives in tankers at the bakery and isstored in silos. Typically holding 50 tons of

sifted flour.

Computer-controlled mixer weighs flour

and water. Batches of dough are mixedevery few minutes.

Yeast, salt and other ingredients are addedautomatically.

Batches of dough are divided into portionsfor 400g or 800 Conical moulders shapedough into balls to produce 8000 loaves


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dough into balls to produce 8000 loavesper hour. g loaves at a speed of125 loaves per minute.

Conical moulders shape dough into ballsto produce 8000 loaves per hour.

First prover allows dough to 'rest' for 6-8minutes.

Panner moulder shapes dough for final

product


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product

Dough spends 50 minutes in final prover andexpands in controlled humidity and temperature.

Bread travels through the oven for 20-25 minutes.Lids are added to some tins to produce flat-toppedbread. 6000 large or 8000 small loaves are baked perhour.

Lids and pans removed before cooling for 2-

3 hours in the cooler.


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3 hours in the cooler.

The bread is sliced and regular samples aretaken away to be inspected to ensure qualityis maintained.

Bread is packaged, stacked and put ontolorries for distribution.

Example 3 Break fast FoodsBreak fast Foods


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Ready-to-eat cereals Quick-cooking/instant cereals

Raw/old-fashioned cereals

Prepar ing Cook edPrepar ing Cook ed

Break fast Cerea lsBreak fast Cereals


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Break fast Cerea lsBreak fast Cereals Use recommended

amount of water.

To prevent lumping,slowly add dry cereal toboiling water or mix first

with cold water to form apaste.

Gently stir cereal with a

fork. Cook cereal until it

thickens and absorbs allthe water.

Prepar ing Ric ePrepar ing Ric e


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Cook over direct heat,

in a double boiler, or inthe oven.

Use recommended

proportions of rice andwater and cook until allliquid is absorbed.

National Chicken Council

Prepar ing Past aPrepar ing Past a


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Add pasta gradually toboiling water.

Simmer just until tender.

Drain but do not rinsecooked pasta.

National Pasta Association

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50373692 8 Bakey Technology