In biological systems, all the conversion processes can take place quickly at relatively low temperatures and mild chemical conditions, because enzymes help to run the reactions with lower energy input.

1. Digital Re-print -
March | April 2013
Additives for flour standardisation
- Part I: Enzymes
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3. FEATURE
Additives for flour standardisation -
Part I: Enzymes
by Lutz Popper, Mühlenchemie GmbH & Co. KG, Germany
I
n biological systems, all the conversion gic reactions. Therefore, it is advised that the most enzymes, amylases also act on sub-
processes can take place quickly at employees in contact with enzymes should stances that are well in contact with water.
relatively low temperatures and wear gloves, mask and goggles. Although Alpha-amylase breaks down unbranched
mild chemical conditions, because with a lower probability because of the moieties of starch molecules, releasing dex-
enzymes help to run the reactions dilution in flour or bread improvers, the trins. These dextrins act as substrate for
with lower energy input. same risk is present for bakers. Therefore, beta-amylase and glucoamylase, which in
enzyme producers are trying to manufacture turn produce sugars like maltose and glucose
Because of the ability to perform very preparations that emit less dust. that can be directly used by yeast. By the
complex reactions under these mild condi- For a long time, α- and ß-amylase were action of amylases, the dough viscosity is
tions, enzymes are produced in industrial thought to be the only enzymes that could decreased (water released from the starch),
scale, mostly by micro-organisms. The devel- be used in the milling industry. This view has the fermentation power and the volume are
opment of new enzymes in short succession changed dramatically since the introduction increased, taste and colour are improved,
all around the world is fueled by increasing of hemicellulases two decades ago, and has the crumb softness is retained and the shelf
competition. High quality and low cost prod- now received another blow through the life is extended.
ucts manufactured with the help of these success of lipolytic
enzymes have the chance to compete better enzymes. There are
in the market. many more enzymes
Enzymes are used in many areas of the (Table 1) that still
food industry. In contrast to most other food play niche roles for
application, enzymes used in the flour indus- certain applications,
try do not show their effects at the moment but which may turn
they are added, that is, right in the mill. In out one day to be as
order to see the effect of enzymes in flour, versatile as the afore-
the baker must add water. This problem of mentioned types.
time and place is the general challenge in the
flour improvement business, but it gets even Amylases
more complex when it comes to enzymes. The most used
But enzymes also have definite advantages as types of amylases
they are specialised on distinct effects, used in flour industry
in very small dosages, natural and completely are alpha-amylase,
deactivated under baking conditions. beta-amylase and
As with all the concentrated natural sub- amyloglucosidase
stances, enzymes pose the risk to cause aller- (glucoamylase). Like Figure 1: Enzyme production scheme
18 | march - april 2013 Grain &feed millinG technoloGy

5. FEATURE
FEATURE
is sensitive machinery, motors or anything As well as being applicable to a wide includes of a 50,000 SKB/g amylase per 100 kg
gram the fully auditable dry steam belt
electric and adversely affected by water. range of work settings, steam can be used sanitation unit (BSU) much less native enzyme
of flour). There is which cleans conveyor
The technology, which is the first of to undertake innumerable cleaning tasks. belts flour with level, saving up to above 400
in to allergen Falling Numbers 3 million
its kind in the UK, uses a continuous flow The system can be used on feeding, mixing seconds, therefore 3 grams or more of the
litres of water per annum.
heating coil system to heat water to such and blending vessels, machinery, conveyor same organisation has used. developed a
The amylase may be also On the other
a high degree that it becomes extremely belts, rollers, pipelines and also general floor central steam systemvery low FNproduction
hand, in flours with for food values, using
hot vapour. The emitted dry steam contains areas, storage spaces and much more. As and packaging areas. This (like 0.1-0.2 grams
trace amounts of amylase is much like a
minimal moisture and efficient cleaning capa- it is applied to the surface, dry steam of 50,000 SKB/g amylase) will not affect the
central vacuum, which facilitates cleaning
bility is produced from the steam pressure leaves very little residue and can byFN but may have the steam effect on the
simply plugging a beneficial hoses into
made on the surface area. almost touch dry, especially central steam pipesand volume yield. for
dough properties without the need
when compared handling cleaning machines. The sophisti-
Is all steam cleaning the same? Glucoamylase can be used for the
cated equipment
So steam is simply steam? Well actually, Also called heavy parts and foror previ-
cleaning of amyloglucosidase plastic
no. Steam can be produced in a range ously parts cleaning. The machines start
gamma amylase, this enzyme breaks
of different grades, each matching dif- starch to its smallest single phase unit and
from a 3kW building blocks, glucose.
ferent industry applications. Picking the It also can work on the144kW units avail- of
reach up to branching points
cleaning method best suited to your able in electric, oil or
amylopectin, as opposed to alpha-amylase.
operation depends upon a number of With this property, glucoamylase coils.
gas heated helps
options including the nature of the sur- Figure 2: Hemicellulolytic enzymes Kopie improving the browning of baked products
face to be cleaned and the type of material and stabilises the fermentation in prolonged
or residue found on crushing or milling appa- fermentation processes. There is no viscos-
Enzyme active malt flour
ratus, conveyors and elevator pits and silos. to any Amylase from fungal sources is mostly ity lowering effect of this enzyme because
To date,need enzymes to start with their vital
Seeds conventional CIP systems have other clean-
alpha-amylase. Most detrimental side activi- it leaves the large starch molecules basically
tended to rely on traditional boiler systems
activities, therefore high amount of enzymes ing method.
ties are prevented by selection of suitable unaffected, at least within the relatively short
which are only required to heat the water step.
are produced during the germination to No additional
subspecies and processing conditions. At time of baking processes.
a maximumbe useddegrees and rely on high
Grains to of 75 for enzymatic purposes will ingredientsdosage, fungalin amylase does not
normal are required
water germinated beforepressure, using a lot
be flow and minimal processing. Enzyme- the steam to improve cleaning
interfere with FN values because it is not Hemicellulase
of active malt flour is produced from germinated
water in the process. power, as efficient cleaning (approx. 95 °C) of
stable at the temperature capacity The term hemicellulase designates
barley, wheat related sites functions of these
Most food or rye. The use hot water is the standard assay. There is another, modi-
produced from the steam pressure a family of enzymes. All the members
that comesare generally similar.
products off the boiler through hoses, made FN test to determine be cleaned and
fied on the surface to the effect of fungal shown in Figure 2 are able to break
using Besides alpha- and beta-amylases, there
foamers, liquid chemicals and other the solvent which employs drops at a high
amylase, power of micro lower maximum down the pentosans (therefore they
sanitation agents. They can use between
are other enzymes in malt flour, like pro- temperature, with minimal 82 °C. present.
temperatures at around moisture are also called pentosanases), but their
200-1,000 litres of water While some blast a
teases and glucanases. per hour to of these However, dos-
The
surface positive effects on baking, somenega-
have clean. They can also have the do the where of specific
age alpha-
tive side effect of sending dangerous bacteria
opposite. Like the enzymes natively found tasks or loca-
amylase
airborne, spreading them malt flour also have
in flour, enzymes from through the plant tions demand
preparations
without killing them. This ‘wet steam’ system
a considerable effect on the Falling Number it, depends on
ingredients
does not use a vapour process. of flour is very
(FN). If the enzymatic activity can be added
their activ-
low, malt flour up to 150 grams per 100 kg toity. In order
improve
Benefits of in order to decrease FN values
can be used dry steam cleaning the solidifica-
to express
to 250-300 seconds.capacity is of FN below
Efficient cleaning In the case produced tion of specific
the activ-
from theenzyme active malt made may result
300 s, steam pressure flour on the substances, for
ity of alpha-
surface to be cleaned andwhen used at below
in sticky doughs even the solvent power instance within
amylase, the
of 50 g per 100 at a The activity of malt flour
micro drops kg. high temperature, with liquid fat appli-
unit for the
minimal moisture present.diastatic power (DP)
is mostly stated as the cation method
test devices
and is continuous steam400 DP. This activity
The usually at around system provides which
developed could
constant steam quality as 80-120 SKB/g.
may be interpreted which can be adjusted congeal with-
by Sandstedt,
by volume and dryness. Water flow and out the use of
Kneen and
Fungal amylase
heating power can be controlled and adapt- additional ingre-
Blish (1939),
ed byUsually fungi control system. Aspergillus
an electronic belonging to dients. SKB, is
the
genusamount of water saved dependsamylase.
The are used to produce fungal upon used. Even
the flow rate of the water system and the
The species are well defined and do not Dry steam
though differ-
pressure employed, but it can save substances.
produce toxic or carcinogenic up to 90 machines
ent suppliers
percentfungi are used. OspreyDeepclean’s dry
The of water grown in large fermentation for different
use different
steam technologyproducing and excreting the
tanks end left will typically use between applications
test methods,
10-30 litres of water per hour, whereasfluid.
desired enzymes to the fermentation a the
The results
tech-
conventional system broth containing the raw
The fermentation will use between 200- are
nology Osprey often
1,000 litresis processed by centrifugation, filtra-
enzyme per hour. converted
Deepclean has
tion, precipitation, ultrafiltrationthe risk of
Conventional cleaning leaves and the like developed SKB.
into is
potentially dangerous residues contaminating
to result in a purified concentrated enzyme available wheat
For in a
food and raw materials. Then is converted to
solution. This concentrate you also have with Falling
range of dry
the issue ofby sprayinto difficult spaces, such
powder getting drying, mixed with bulk Numbers
steam machines
as material to standardise the activity and free
tight crevices in storage areas or complex for between 300
different
shaped equipment. provide ease of usage in
flowing agents to applications, the
and 350 s,
Dry steam sanitises surfaces, penetrating
mills. As a dry powder most enzymes are typical dosage
based on many
cracks, stable and can be kept for years without
very crevices and other hard-to-reach areas is adjusted as
years’ experi-
where manual and traditional cleaning provides a
losing much activity. Figure 1 methods, ence ofSKB per
500 creating
which mainly the production of enzymes from
scheme for rely on potentially hazardous kg of flour
bespoke steam
chemicals,animals and microbes.
plants, fail to achieve the required standards. solutions. is, This
(that 1
&&
Grain feed millinG technoloGy
Grain feed millinG technoloGy march - april 2013 | 1119
march - april 2013 |

7. FEATURE
impacts on dough and baking properties
vary widely.
It is assumed that pentosans form a
network with gluten; the more pentosans
are involved, the firmer the network.
Because they bind large amounts of water
(approximately 10 times their dry weight),
they reduce the availability of water for
the gluten reducing its expandability.
Additionally, pentosans can be cross-linked
to each other by the so-called oxidative
gelation, increasing their ability to bind
water further.
That is a main reason why darker
wheat flours and mixtures containing rye
flour have a lower volume yield than
white flours. The volume yield of all flours
can be increased considerably by adding
hemicellulases.
Many of these enzymes are derived
from Aspergillus strains selected for or
specialising in the production of hemicel-
Figure 3: Action of protease on gluten lulases.
Hemicellulases are often sold in com-
pounds with amylase and other enzymes.
Table 1: Enzymes suggested for bread and flour improvement (not exclusive) The most common hemicellulase for bak-
ing applications is an endo-1, 4-ß-xylanase.
Enzyme Claimed Effect
It is not possible to give a general dosage
recommendation as there is no stand-
ard method of determining hemicellulase
Alpha-amylase, bacterial Oven-rise, anti-staling, liquefaction
activity. The available methods are usu-
Alpha-amylase, cereal Oven-rise, anti-staling ally based on determining the release of
Energy supply for yeast, dough & bread reducing sugars, the reduction of viscosity
Alpha-amylase, fungal or the breakdown of synthetic or coloured
structure
molecules and are very difficult to relate
Alpha-amylase, maltogenic, intermediate heat to each other. Moreover, even the use of
Anti-staling
stable
a standard method for different hemicel-
Ascorbic acid oxidase Protein strengthening lulases does not necessarily permit con-
clusions in respect of baking properties,
Beta-amylase Energy supply for yeast, browning, taste
presumably because the points at which
Branching enzyme (glucotransferase) Water binding hemicellulases of different origin attack the
pentosan molecules are too various.
Cellulase Water binding
Furanosidase, arabinofuranosidase Dough structure, water binding Protease
Ferulic and cumaric acid esterase Dough structure, water binding Proteases (also known as proteinases
or peptidases) split the protein strands
Glucoamylase, (amyloglucosidase) Energy supply, colour, flavour of the gluten molecule (Figure 3) and
Glutathion oxidase Protein strengthening thus lead first to a softening and then to
a complete collapse of the structure. A
ß-glucanase Structure, liquefaction purified single and very specific protease
Glucose oxidase, galactose oxidase, hexose would only be able to break down a few of
Protein strengthening
oxidase the peptide bonds, resulting in only limited
softening.
Hemicellulase, xylanase, pentosanase Dough structure, water binding, volume yield
With short gluten structures a slight
Laccase, polyphenol oxidase Dough strengthening softening may well be desirable; in this
case it has a similar significance to the use
Carboxyl esterase (lipase, phospholipase, Flavour, in-situ emulsification, dough stability
galactolipase etc.) and volume yield, dough brightening of L-cysteine. The proteolytic action is
more time-dependant than the function
Lipoxygenase, lipoxidase Dough structure, decolourization of cysteine. As a result, it increases with
Exo-Peptidase Colour, flavour the fermentation time of the dough. That
is why there is a considerable demand for
Peroxidase Protein strengthening enzyme preparations that do not contain
Protease, proteinase, endo-peptidase Protein relaxation, liquefaction even traces of protease.
The use of protease is less crucial with
Pullulanase Structure, water binding
flours that are rich in gluten. It is even very
Sulfhydryl oxidase Protein strengthening common in the production of pan (toast)
bread, where a soft dough that precisely
Sulfhydryl transferase Protein strengthening
fills the tin is required. Proteases are also
Transglutaminase Protein cross-linking, gluten stabilization very useful in the production of cracker,
20 | march - april 2013 Grain &feed millinG technoloGy

8. FEATURE
such as the tyrosine groups in protein or the
feruloyl residues in pentosans.
The oxidative cross-linking of the pen-
tosans is called oxidative gelation, a reaction
resulting in increased dough firmness and
dryer dough surfaces. The limiting factor
in this process is the availability of oxygen
because of other chemical and biochemical
reaction consuming oxygen.
Therefore, the conditions for oxidases
are only good on the surface of the dough
where plenty of oxygen is always available.
This limitation can be solved by technical
measures during dough preparation, for
Figure 4: Reaction of glucose oxidase and some example overpressure or the supply of
probable effects on dough components
extra oxygen through the mixing tool.
Carboxyl esterases
The term carboxyl esterase comprises
all lipolytic enzymes, for example (triacyl)
lipase, phospholipase and galactolipase. They
all catalyse the hydrolysis of acyl residues
(fatty acids) from lipids. Wheat contains
about 2.5-3.3 percent lipids, a typical bread
flour about 2.5-2.7 percent (Chung & Ohm,
2009), but only about 1 percent are free
lipids that are easily accessible by lipolytic
enzymes. A schematic representation of the
lipids composition of wheat flour is given in
Figure 5. Lipase converts non-polar lipids
Figure 5: Classification and distribution of the main lipids in wheat flour into the more polar structures diglycerides
(averages; % d.s.; modif. from Pomeranz and Chung, 1978, using data from and monoglycerides, i.e. emulsifiers (Figure
Chung and Ohm, 2009) 6). Lipids of wheat flour are already polar to
some extent, namely phospholipids and gly-
colipids are converted into more polar and
biscuit or wafer flours where elasticity of is also a rich source of GOX. The enzyme hydrophilic lyso-forms by phospholipases
the gluten is not desirable. stems from the pharyngeal glands of the and glycolipases.
bees. However, its suitability is rather The in situ formation of mono- and dig-
Glyco oxidases restricted by the taste of its carrier. lycerides from wheat lipids results in dough
There are several oxidoreductases in One effect of GOX in the dough is to strengthening and larger volume yield, but
nature that convert sugar molecules into oxidize glucose to form gluconic acid with according to the author’s findings doesn’t
the corresponding acids, or, as in the case the aid of atmospheric oxygen, but the slight have a significant effect on starch retrograda-
of sorbitol oxidase, that convert a sugar souring that occurs in the process is negligi- tion and hence bread staling. This is in con-
alcohol into the corresponding sugar. The ble; its other effect is to transform water into trast to the effect of mono- and diglycerides
most common oxidase (from a commercial hydrogen peroxide (Figure 4). This oxidizing which are added to a bread formula: due
perspective) is glucose oxidase. Other exam- agent acts on the thiol groups of the gluten, to interaction with starch they are able to
ples are maltose or galactose oxidase. More either directly or via several pathways, induc- reducing the staling rate. On the other hand,
generic terms used for all these enzymes are ing formation of disulphide bonds and thus their effect on volume yield is very limited.
hexose oxidase or pyranose oxidase. tightening of the protein. Since hydrogen Most probably, the action of enzymatically
The enzyme glucose oxidase (GOX) is peroxide is a rather non-specific oxidizing formed emulsifiers on volume yield is pro-
usually derived from the mould Aspergillus, agent, it may also react with other reducible nounced because they are already located at
sometimes from Penicillium species. Honey substrates, for instance phenolic component the right sites of the dough for improving the
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Grain &feed millinG technoloGy march - april 2013 | 21

9. FEATURE
omitted; the dough pieces will keep the
shape given by the cutting; shrinkage and
bending in the oven as well as the for-
mation of hairline cracks (checking) are
avoided. With suitable amylases, expen-
sive recipe components such as milk
solids otherwise necessary for sufficient
browning can be omitted. Furthermore,
the whole process will be less dependent
on flour quality.
Other flour applications
Enzymes have also been introduced
into flour applications others than bak-
ing, for example noodles or steamed
bread. For steamed bread the desired
properties are similar to those in bread
baking, but the technology is quite dif-
Figure 6: Effect of carboxylesterases on wheat lipids ferent and requires different types of
enzyme compounds. In many types of
steamed bread, specific lipases are very
useful, providing stability, volume and a
bright crumb colour.
Except for certain types of Asian
noodles, for example Japanese udon
noodles, a firm bite and a high cooking
tolerance are advantageous. For instant
noodles, the requirements are quite
different, because the reduction of oil
uptake during frying and a fast water
uptake upon cooking are of utmost
importance. Furthermore, avoiding the
cracking of dried noodles is a typical
aim, although this problem is caused in
many cases by inadequate drying condi-
Figure 7: Cross linking of protein by transglutaminase tions. Finally, the colour of the fresh or
dry noodle is important. A bright colour
without speckles is a desirable property
of many but not all types of noodles. All
protein properties; but for anti-staling effects, and glutamine groups to work. Although of these challenges can be approached
not enough emulsifier is formed to interfere lysine is a limited amino acid in flour, the by enzymes, namely by carboxyl este-
with starch retrogradation. levels are enough for transglutaminase to rases and lipoxygenases.
Nevertheless, they have a distinct work. The result is a strengthening effect
effect on the shelf life of bread because on the dough, like ascorbic acid. References
they create a better ‘starting point’ at the Because it is rather expensive com- Chung, OK, Ohm, JB, 2009. Wheat Lipids. In:
beginning of the storage due to improved pared to ascorbic acid, its use is limited. Wheat - Chemistry & Technology, Khan, K,
volume and crumb structure. With the A special usage area can be in very Shewry, PR (ed.), AACC Press, 363-399.
staling rate unchanged, this results also in long or retarded fermentation processes Pomeranz, Y and Chung, OK, 1978. Interaction
a better structure (crumb softness) at the where very low amounts of the enzyme of lipids with proteins and carbohydrates in
end of the storage period. will work sufficiently long. breadmaking. J. Am. Oil Chem. Soc., 285-289 .
Interestingly, it is being disputed Sandstedt RM, Kneen E and Blish MJ, 1939.
whether the doughs have to contain Enzymes for biscuits, crackers A standardized Wohlgemuth procedure for
additional fat, and if so, what kind of and wafers alpha-amylase activity. Cereal Chem. 16,
fat, for the lipase to work satisfactorily. Whereas a high protein content and 712-723.
According to our findings, fat reduces the strong gluten are desired properties in
efficacy of lipase, probably by ‘distracting’ many bread processes, flours with lit-
the lipase from the ‘right target’, i.e. the tle and weak gluten are preferable for
flour lipids. durable baked goods. The tendency of Read the second part of this article
Initially, there was also the problem dough to spring back after rolling and in the next issue of Grain and Feed
of a possible impairment of taste due to the undesired formation of gluten lumps Milling Technology. Lutz Popper will
the release of flavour-active fatty acids, in wafer batter are the reasons for this discuss additives other than flour and
particularly if butter is involved. The requirement. Whether a flour with low standardisation services.
most recent carboxyl esterase are more and weak protein is available or not,
specific in this concern and hence do not the use of elasticity-reducing agents will
affect the flavour in most applications. have benefits in all stages of the process:
The lamination will be more uniform;
Transglutaminase reduction of the thickness of the dough More inforMation:
This enzyme causes bond formation sheet can be performed faster and more
Website: www.muehlenchemie.de
between protein folds or different pro- reproducibly; relaxing periods for the
tein strands (Figure 7). It needs lysine dough sheet can be shortened or even
22 | march - april 2013 Grain &feed millinG technoloGy

11. This digital Re-print is part of the March | April 2013 edition of Grain & Feed
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first published in 1891
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Part I: Enzymes
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