The most commonly used material to strengthen gluten is ascorbic acid, also called vitamin C. The material itself is originally a reducing rather than an oxidizing agent, but it is converted into an oxidative substance, namely dehydroxy ascorbic acid (DHAA), through the action of flour enzymes during dough preparation. DHAA basically inactivates the glutathione molecules which break down the sulfur bonds between the gluten molecules (Grosch and Wieser, 1999). With this action, dough mixing results in sulfur bonds protection without excessive breakdown, which in turn leads to dough with desired structure.

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Additives for flour standardisation
- Part II:Additives other than enzymes
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3. T
he most commonly used material
to strengthen gluten is ascorbic
acid, also called vitamin C. The
material itself is originally a reducing rather
than an oxidizing agent, but it is convert-
ed into an oxidative substance, namely
dehydroxy ascorbic acid (DHAA), through
the action of flour enzymes during dough
preparation. DHAA basically inactivates
the glutathione molecules which break
down the sulfur bonds between the
gluten molecules (Grosch and Wieser,
1999). With this action, dough mixing
results in sulfur bond protection without
excessive breakdown, which in turn leads
to dough with desired structure.
Pure ascorbic acid is added to the flour in
mills at rates of typically 0.5-3 grams per 100
kg of flour. This dosage may go up to 6-10
grams per 100 kg in very weak flours or for
weakening applications like frozen dough.
Ascorbic acid is mainly produced by com-
plex biochemical processing of glucose and
sold as powder with different granule sizes.
There are also natural sources for ascorbic
acid, for instance acerola fruit powder, but
these are too expensive compared to the
synthetic ones.
Potassium bromate
Potassium bromate as a strong oxi-
dative is still used as flour improver in
many countries in the world. The very
long lasting effect of bromate starts
later than the effect of ascorbic acid and
allows easier processing of the dough.
Bromate creates new disulfide bonds
resulting in more resistant doughs but
it also oxidizes glutathione and hence
prevents gluten weakening, just like
ascorbic acid but without the help of
the flour’s enzymes.
Usage of bromate in flour industry
is prohibited in the EU and many other
countries because of the health con-
cerns and its unstable/fire-accelerating
nature.
Azodicarbonamide
Azodicarbonamide (ADA) is utilized
in flour industry because of its oxidative
action. Its dosage is similar to ascorbic
acid (with a recommended maximum
of 45 ppm), but the dosage tolerance is low,
so even a slight over dosage may result in
bucky doughs and rough bread surfaces. It is
a flammable material and its usage in food-
stuff is not permitted in the EU and several
other countries.
Others
Other than the ones stated above, there
are many oxidative materials and oxidation
processes utilized throughout the world.
Chlorination, usage of peroxides, iodates,
persulfates, cystine and oxidative enzymes
are some of these. All of these methods dif-
fer by their effects on flour/dough, and their
pace of action.
Dough relaxation, softening,
reduction
Dough with ‘short gluten’ (low extensibil-
ity) is hard to process. In addition to this, gas
produced during fermentation will not be able
to expand the dough sufficiently and hence
the volume of the end product will be small.
Furthermore, for products like biscuits, crackers
and wafers, the optimum processing condi-
tions can be reached when gluten structure is
weaker than normal. In these situations, reduc-
tive materials are used to break the disulfide
bonds and provide gluten with more flexibility.
Cysteine
L-cysteine, a sulfur-containing amino acid
found in diverse proteins, breaks down the
disulfide bonds between and within gluten
molecules and becomes attached to the
bond forming regions. This prevents gluten
from getting stiff, and a mobile, flexible but
still coherent structure is secured. This effect
seems to be the opposite of ascorbic acid’s,
but actually they seem to complement each
other in some processes. This synergy is
especially used in frozen dough processes:
Ascorbic acid provides the necessary fer-
mentation stability whereas cysteine gives
extensibility to gluten strands which have
shorten because of freezing.
Others
Inactive yeast preparations are rich in
reducing material, but their dosage (500 –
5,000 ppm) and price are relatively high,
as compared to cysteine. Levels of other
reducing agents like sodium metabisulfite
and sulfur dioxide which are used as dough
softening agents in biscuit and cracker pro-
duction are limited to 50 ppm. This amount
is not sufficient to observe a softening effect
in strong flours. Furthermore, many coun-
tries require declaration if the concentration
of residual sulfur dioxide exceeds 10 ppm
Table 1: Suggested emulsifiers with potential use in baking applications
Emulsifier
Common
abbreviation
HLB Application and benefit
Acetyl esters of monoglycerides AMG 2.5-3.5 Whipped cakes, volume
Calcium stearoyl lactate CSL 7-9 Bread, shelf-life, volume
Diacetyl tartaric esters of monoglycerides DATEM 9.2 Bread, shelf-life, volume
Ethoxylated mono- and diglycerides
(polyglycerates)
EMG 12-13
High-fibre bread; shelf-life
(combined with monoglycerides)
Glycerol monostearate (non self-emulsifying) GMS 3.7 Shelf-life
Glycerol monostearate (self-emulsifying) GMS 5.5 Shelf-life
Lecithin LC 3-4 Shelf-life, dough properties
Lactyl esters of monoglycerides LMG 3-4 Whipped cakes, volume
Mono- and diglycerides MDG 2.8-3.8 Bread, cakes, cookies, volume
Polyglycerol ester PGE 12-13 Whipped cakes, volume
Propylene glycol monostearate PGMS 1.8 Whipped cakes, co-emulsifier
Polysorbate 60 PS 60 14.4 Whipped cakes, co-emulsifier
Succinyl monoglyceride SMG 5-7 Yeast leavened baked goods; volume
Sorbitane monostearate (e.g. SPAN 60) SMS 4.7-5.9 Whipped cakes, volume
Sodium stearoyl lactate SSL 18-21 Bread, shelf-life, volume
Sucrose esters SUE 7-13 Bread, cake, volume
Additives for flour standardisation -
Part II:
Additives other than enzymes
by Lutz Popper, Mühlenchemie GmbH & Co. KG, Germany
Grain&feed millinG technoloGy12 | may - June 2013
FEATURE

4. in the final product. Figure 1 compares the
effect of cysteine and inactive yeast on the
extensibility and resistance towards exten-
sion in a standard wheat flour dough.
Emulsifiers
Emulsifiers are polar molecules that can
interact with many constituents of Emulsifiers
that interact with gluten during mixing process
strengthen the bonds between protein chains,
but they also provide a lubricating effect that
allows the chains to slide over each other eas-
ily. They are involved in the stabilisation of the
gas bubbles in dough by binding to the bound-
ary layers. As a result, dough elasticity, oven
rise and volume increase, and the crumb pore
size reduces. The bakers will note an increase
in the practical water absorption, although the
dough rheological measurements may not
confirm this percep-
tion. Other emulsifiers
strongly interact with
the starch delaying ret-
rogradation and staling
and thus provide bread
with improved and
prolonged softness and
freshness. Some have
potent foaming ability
because of their sur-
face-active nature and
are used as whipping
agents for sponge cake
and the like. They ease the mixing of water
and fat and hence improve fat dispersion in
bakery products that contain larger amounts of
fat, such as biscuits, or in liquid systems such as
wafer batters. They also decrease the amount
of necessary fat, contributing to cholesterol,
calorie and cost reduction.
Lecithin
Lecithin is an emulsifier which has been
used in bakery products for a long time. Once
egg yolk was used as the source of lecithin,
but nowadays concentrated lecithin obtained
from soy beans, canola or sunflower seeds
is used. The most obvious benefit of lecithin
is to lower the stickiness of the dough and
improve its machinability. Other than this,
lecithin softens the crumb due to its interac-
tion with starch. But its effect on volume is
less than that of its synthetic counterparts.
The dosage of lecithin is about 30-150 g per
100 kg of flour (0.03 – 0.15 %). Low dosages
increase the processing quality of the dough,
whereas high dosages increase dough stability
and fermentation tolerance, improve crumb
structure and prolong shelf life.
Mono- and diglycerides
These molecules are formed by breaking-
off fatty acids from edible fats and oils. The
forms that are preferred as flour improver
are the ones that prevent staling best. This
property is found in linear saturated fatty acids
that interact best with starch, and the most
effective of them all is glycerol monostearate.
The dosage starts at 0.05 percent and may
go up to one percent, especially in high-fat
products.
Diacetyl tartaric esters of mono-
and diglycerides (DATEM)
DATEMs currently are the most effective
emulsifiers for bread volume. They are various
molecules formed by esterification of mono-
and diglycerides (obtained from edible oils)
with mono- and diacetyl tartaric acid. Some
of these molecules are more active than the
others (Köhler, 1999), but the effect of the
mixture is better than any single type of pure
emulsifier.
DATEM is rather used in bread improvers.
The optimum dosage is about 400 g per 100 kg,
Figure 1: Effect of reducing agents on the dough consistency
Grain&feed millinG technoloGy may - June 2013 | 13
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FEATURE

6. but much lower dosages are used actually because
of the high prices. We mentioned that the effect
of lipolytic enzymes is comparable to emulsifiers.
Recent studies are focused on producing carboxyl
esteerases that may reduce DATEM usage, or
replace it completely.
Sodium and calcium stearoyl
lactylate (SSL and CSL)
These emulsifiers are formed by the
esterification of stearic acid with lactic acid.
They act like DATEM, with a slightly weaker
effect on dough stability and baking vol-
ume. On the other hand, they are more
effective in preserving the crumb softness.
Furthermore, they are more suitable for
bakery products that require a softer crust.
Other emulsifiers
Other than the ones stated above, there
are many more to be used in high-fiber prod-
ucts, cake bases etc. The distinctive property
among them is the HLB value (Hydophilic-
Lipohilic Balance). This value shows if the
emulsifier displays a more hydrophilic or
lipophilic character. Emulsifiers for high bread
volume yield rather have an HLB of 7 or
higher, while emulsifiers that improve the shelf
life of the crumb softness exert a lower HLB,
probably because they have to be able to
interfere with the non-polar interior of starch
helices. Table 1 provides a list of common
emulsifiers used in baking applications.
Acidifiers and acidity regulators
With germination, high amounts of amy-
lase are formed in grain. This enzyme works
like amylase added to the flour, but has
a stronger impact on lowering the Falling
Number (FN). If there is too much cereal
amylase, the baking properties are negatively
affected and the FN is too low. To restore
good baking properties, the dough may be
acidified by natural lactic acid fermentation,
resulting in a sour dough. This prevents the
cereal enzymes from finding the optimum
conditions and hence their activity decreases.
But the taste and aroma developed during
acidification of the dough may not be well
received by everyone. Moreover, this proc-
ess takes a long time. Other than natural
acidification, agents that are allowed in
foodstuff, like fruit acids, salts of these acids,
carbonates and phosphates may be used. By
careful adjustment of these, the pH range
(acidity) of the dough may be altered to a
level where the enzymes cannot work opti-
mally. Most preferred of these additives are
the ones that keep the pH value at a desired
level regardless of the chemical changes in
the dough, called buffering agents. A typical
dosage is 50-200 grams per 100 kg of flour.
It should be kept in mind that phosphates
and carbonates add to the ash content of
flour. For sprout-damaged wheat, it is advisable
to lower the extraction of enzyme-rich outer
layers of the kernels (that is, to decrease the
milling yield) and produce a whiter flour that
allows addition of ash-increasing improvers.
Bleachers
Even though customers are getting more
and more aware of the fact that darker milled
flours are richer in vitamin and mineral content,
bread with a crumb as white as possible is pre-
ferred in many regions. Bleaching of the carote-
noids which give the flour a dark colour, namely
lutein, can be achieved with oxidative materials.
Soy Flour
The best-known legal material for this applica-
tion is enzyme-active soy flour. A clearly visible
effect can be achieved at dosages around 0.5
percent. There are two types of enzyme-active
soy flour in the market: deoiled and untreated.
The bleaching effect is related to the lipoxygenase
enzyme in soybeans. Deoiled soy flour may have
lost some or all enzyme activity during the proc-
ess and hence may not be suitable for this pur-
pose, but nevertheless there are enzyme-active,
deoiled soy flours available. On the other hand,
untreated soy flour may cause an unwanted bitter
taste because of the enzyme urease.
Because the soy flour’s bleaching effect is
due to an enzymatic reaction, the bleaching
only starts after contact with water, that is,
during dough mixing.
Powerful oxidatives
Benzoyl peroxide, potassium bromate and
their derivatives cause bleaching because of their
powerful oxidative effects. Added at dosages of
5-10 g per 100 kg, the effect of benzoyl perox-
ide starts during storage of flour and the process
is completed in about 1-3 days. These chemicals
pose health risks by undesired residues and
reaction products remaining in the final food or
at least because of their inflammable, fire-accel-
erating or even explosive nature. Furthermore,
their usage in food is not permitted in the EU
and in several other countries.
Other agents
The colour lightening effect on crumb experi-
enced with the usage of ascorbic acid, emulsifiers
and some enzymes is mostly a physical illusion.
Using these improvers, one can have smaller and
more evenly distributed pores which cast less
shadow and therefore the crumb seems whiter.
Using lipases also may contribute to a bleaching
effect provided that there is enough of oxygen in
the dough. The unsaturated fatty acids produced
by lipase are converted to hydroperoxides by the
flour’s own lipoxygenase, and these molecules in
turn bleach carotenoids.
Vital wheat gluten
Vital wheat gluten is produced by separating
the water-insoluble proteins of wheat flour from
the starch and soluble materials by a thorough
washing process with water and drying of the
resulting wet gluten. The material obtained via
this process consists of around 80 percent glu-
ten plus some remaining starch, lipids and non-
starch carbohydrates (Pomeranz, 1988). When
added to the flour, vital wheat gluten increases
the protein strength. This effect is easily detected
with the help of flour analysis equipment like the
Alveograph or the Extensograph.
The properties of gluten added from outside
are different from those of native gluten. The
difference that can be observed by determining
the water absorption and rheological properties,
resulting from partial denaturation of the protein
during the drying process. Because of this, a
proper drying practice is the most important
factor in preserving the function of vital gluten.
Some manufacturers do not worry about keep-
ing the quality of the protein, because vital gluten
is sometimes still considered as a byproduct of
starch production. Using this low quality vital
gluten increases the protein content of the flour,
but does not improve the gluten properties.
The water absorption capacity of added vital
gluten is lower than that of native gluten. A ratio
of 1.3-1.5 parts of water per one part of vital glu-
ten can often be observed, while this ratio goes
up to 2.5-3 parts of water per one part of native
gluten in flour. Also the structure of vital gluten
becomes shorter because of the drying process.
Because of this, softer wheat varieties are more
suitable for producing valuable vital gluten.
The colour of gluten is also an important
criterion in the market. Vital gluten mostly has a
grayish tone that will also contribute to colour of
flour. This is not a desired quality though; bright
white or yellowish tones are preferred in flour
industry. The colour is affected by the wheat
variety, extraction and drying methods.
Services
Mühlenchemie’s mission and practical knowl-
edge lie in selecting and combining the individual
raw materials described. The optimum composi-
tion brings about synergistic effects. Since wheat
qualities fluctuate, Mühlenchemie helps mills to
produce flours with consistent baking qualities.
The samples of flour sent in by the mills are
subjected to a rheological analysis in the compa-
ny, and the results are used to develop specific
compounds for each customer. Baking trials are
then carried out to test the flour improvers for
functionality before they are offered to the mill
as Alphamalt.
Besides customized products, Mühlenchemie
offers whole systems. The EMCEbest WA series
increases the water absorption capacity of
doughs, and thus the yield, and results in a more
succulent crumb and a longer shelf life. The
EMCEgluten Enhancers can save on vital wheat
gluten at 1/10 of its usage level, strengthen weak
flours and make it possible to use composite
flours.
Mühlenchemie offers mills further support in
their daily work in the form of seminars, labora-
tory equipment and technical training courses
and helps with the quality control and improve-
ment of flours on the spot.
More inforMation:
Website: www.muehlenchemie.de
The first part of this article, which dis-
cusses enzymes and flour standardisa-
tion, is in the March/April 2013 issue
of Grain and Feed Milling Technology.
It is also online at www.gfmt.co.uk
Grain&feed millinG technoloGy14 | may - June 2013
FEATURE

8. www.gfmt.co.uk
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Part II:
Additives other than
enzymes
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May-June2013
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