BREAD STALING – HOW TO ANALYSE?

3rd of September 2019

Kees Veeke – Technical Service Manager Baking

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• Bread

• Baguette

• Cake

• Muffins

• Biscuits

• Crackers

• Gluten-free bread

• Pizza

• Pasta

• Rice noodles

• Maize tortillas

• …

Baking application products

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• Based on knowledge of the ingredients (e.g. flour) and understanding of the

underlying mechanisms, processes or changes taking place during

– mixing

– fermentation

– baking

– cooling

– storage

pilot-scale bakery in-house

(also pilot for dairy, brewing etc.)

Application R&D in baking

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PhospholipidsTriglycerides Galactolipids

Amylopectin (70-80%)

Amylose (20-30%)

Arabinoxylan

Cellulose

Arabinogalactan peptides

Gliadin

30-80 kDa

Glutenin

>80 kDa

Gluten (80-85%)Albumins

Globulins

70-80%

2-3%

2-3%

10-15%

8-15%

Composition of wheat flour

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PhospholipidsTriglycerides Galactolipids

Amylopectin (70-80%)

Amylose (20-30%)

Arabinoxylan

Cellulose

Arabinogalactan peptides

Gliadin

30-80 kDa

Glutenin

>80 kDa

Gluten (80-85%)Albumins

Globulins

70-80%

2-3%

2-3%

10-15%

8-15%

amylases

proteases

xylanases

lipases

Composition of wheat flour

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Crust color

• amylases

• amyloglucosidase

• protease

Volume

• amylases

• proteases

• (phospho)lipases

• oxidases

• (hemi)cellulase

Crumb elasticity

• hemicellulase

• amylases

Initial crumb softness

• (hemi)cellulase

• (phospho)lipase

Crumb structure

• (fungal) α-amylase

• (hemi)cellulase

• (phospho)lipase

• glucose oxidase

Crust crispiness

• glucose oxidase

• protease

Freshness / shelf life

• maltogenic amylase

• alpha amylase

• phospholipase

Taste & flavor

• amyloglucosidase

• amylase

• protease

Quality parameters brought by enzyme classes

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• 4 essential ingredients for breadmaking:

– flour (100%)

– water (50-65%)

– yeast (1-6%)

– salt (0.5-2%)

• Major steps in baking process:

– mixing

– fermentation

– baking

– storage

Breadmaking: ingredients + steps

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Breadmaking: process steps

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Breadmaking: process steps

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Breadmaking: process steps

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Breadmaking: process steps

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Maltogenic amylaseCuts starch chains

Glucose oxidaseCrosslinks gluten and AX

• Small adaptations on molecular level have a large impact on meso- and macroscale

• Many enzymes have a narrow dose-optimum (risk of overdosing)

PhospholipaseCreates emulsifiers in situ

without enzyme without enzyme

GOX helps to make a strong,

dry dough and increase

bread volume

Phospho-lipase helps to

stabilize the dough and

increase bread volume

MAM reduces the extent

of bread staling during

storage

Enzyme examples impacting breadmaking

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• Quality deterioration of bread during storage:

– crumb: from soft and resilient to firm and crumbly

– crust: from crispy to tough/leathery

– loss of flavor

• Underlying processes on different length scales

– moisture evaporation to environment

– moisture migration from crumb to crust

– moisture migration from gluten to starch

– …

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Bread staling

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• Starch retrogradation = major contributor:

– adjacent amylopectin branches intertwine to form double helices

– neighboring double helices crystallize

– water trapped in crystal (withdrawn from gluten)

• Crystallization happens more quickly at temperatures between

4-14 °C

• Retrogradation can be reduced enzymatically, especially by

maltogenic amylases

water bound to

amylopectin crystals

Top view: crystal of 6 double helices

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Main reasons for bread staling

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• Exo- and endo-amylase activity on gelatinized starch (during baking)

• Sets maltose (and short oligosaccharides) free

exo-activity

endo-activity

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Maltogenic amylase as freshness enzyme

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Enzyme

• acts on amorphous starch chains

• cuts short fragments from amylopectin branches

Consequence of enzyme activity:

• amylopectin branches become too short to form double helices

• less double helices to participate in crystallization

• reduced level of starch retrogradation during bread storage

→ Bread stales to lesser extent: softer and more resilient crumb

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Maltogenic amylase as freshness enzyme

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• Heat stable endo-acting bacterial or malto tetraogenic α-amylase:– cut starch chains internally after starch gelatinization (during baking)

– lower extent of double helix formation and crystallization

– prolonged crumb softness during storage

• (Phospho)lipase:– higher loaf volume

– homogeneous crumb structure

– formation of free lipids: starch-lipid complexes

• (Hemi)cellulase:– higher loaf volume

– homogeneous crumb structure

– interferes with water migration

– lower initial softness

Specific combinations/ratios of enzymes tailored to offer solution for specific applicationPage 17

Other enzymatic freshness solutions

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• Crumb-softening emulsifiers: MAG, SSL

– formation of starch-lipid complexes:

• starch chains form single helix with cavity (where lipid resides)

• not possible to intertwine to double helix any more

• reducing level of retrogradation

– can interfere with water migration between starch and gluten

• Hydrocolloids

– interfere with water migration

– act as water ‘buffer/container’

– prolong crumb moistness

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Non-enzymatic freshness solutions

top view

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• Parbaked bread– processes involved in staling similar to conventionally baked bread:

• depending on storage temperature (RT, fridge, freezer)

• moisture migration (smaller gradient crumb-crust)

• protein dehydration

• starch recrystallization

– retrogradation reset (crystals molten) during final bake-off

– impossible to undo moisture migration -> adjust baking protocols or water

content to minimize impact

• Cake– higher moisture content

– lower impact of flour constituents:• weaker (if any) gluten network

• slower retrogradation processes

– similar enzymes can be used as in bread, but typically at higher concentration

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Staling in other baking applications

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• Biochemical analyses of enzymes:– main activity

• at specific temperatures

• after temperature treatments (thermostability)

• at certain pH’s

• in presence of sugar(s)

– impact of small molecules on activity

– …

• Analyses on baked product wrt staling:

– moisture content

– Texture Analyzer: firmness and resilience of crumb (on macroscale)

– TD-H+-NMR: mobility of proton populations (on mesoscale)

– calorimetry: amylopectin crystallinity (on micro-mesoscale)

– HPAEC: presence of oligosaccharides

– sensory panel

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Analytical capabilities with regards to staling at DSM

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• To discriminate firmness from resilience

• Resilience ~ level of elasticity of a sponge

• Optimize various TA parameters to increase discriminative power:– Probe:

• plate pressing on top of smaller piece of bread crumb

• cylinder pressing in middle of full bread slice

– Strain: 5 – 75%

– Time interval between indentations: 1 – 30 s

– Compression speed: 0.5 – 5 mm/s

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Get as much as possible from TA

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Interpretation of TD-NMR ‘populations’

A B C D E F

Peak 1

Amplitude (A1) ~

retrogradation enthalpy

Peak 4

Time (T4)

~ firmness

Peak 2-3

Time (T2-3)

~ resilience

A B C D E

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The amplitude of the population “A” increases with staling

and is well correlated with the retrogradation enthalpy (i.e.

relative amount of amylopectin crystals), measured by DSCThe relaxation time of the population “D” decreases with

staling and is correlated with the crumb firmness,

measured by TA

DSM anti-staling enzyme clearly leads to less retrogradation and a softer bread crumb

TD-NMR shows changes during bread stalingand benefit of anti-staling enzyme

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Blank

Bz MAM 75ppm

Bz MAM 100ppm

Bz Master 15ppm

Bz Master 30ppm

Ball size increases

with storage time

Each enzyme has a unique

correlation (slope and plateau),

with a clear dose-response.

The relaxation time clearly

increases with storage time

relaxation time of population “C”

TD-NMR gives insight in impact of various enzymes on bread crumb resilience

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Calorimetry:

measures heat related to physical processes (e.g. crystallization, melting, denaturation…)

taking place in a sample

• Differential Scanning Calorimetry (DSC)– discrete measurements, in which pieces of bread are heated in a sealed pan in a controlled way

– gives enthalpies and melting temperatures, e.g. of amylopectin crystals, as a function of T

– typically used to indicate relative amount of amylopectin crystals present in bread during staling

• Microcalorimetry– continuous measurement of larger piece of bread, kept in a vial at one stable temperature

– very reproducible and sensitive measurement of heat flows as a function of time (usually days)

– gives indication of kinetics of amylopectin crystallization process

Calorimetry as tool to study bread staling

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• Extent of starch retrogradation

• Lipid melting temperature (for cake/emulsifiers)

• Protein denaturation temperature (for cake)

• …

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Calorimetry on baked products

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Sensory evaluation of baked products

Diverse sensory technologies for objective evaluation

• Descriptive methods

• Discriminative methods

• Quality ratings

• Hedonic / liking scoring

Product characteristics e.g.

• hardness – softness

• dryness - moistness

• cohesiveness

• crumbliness

• crispiness/crunchiness (for some cookies/crackers)

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Questions?

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BRIGHT SCIENCE. BRIGHTER LIVING.

While making reasonable efforts to ensure that all information in this presentation is accurate and up to date,

DSM makes no representation or warranty of accuracy, reliability, or completeness of the information.

The information provided herein is for the informational purposes only.

This publication does not constitute or provide scientific advice and is without warranty of any kind, express or implied.

In no event shall DSM be liable for any damage arising from the reader’s reliance upon, or use of, this presentation.

The reader shall be solely responsible for any interpretation or use of the materials contained herein.

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