World Grain - May 2008 - 48

FEATURE: ENZYMES IN BREADMAKING

Fig. 4 - Potential reasons for future growth
of the bakery enzyme market
* Gluten improvement
or replacement
- Bread
- Noodles
- Gluten-free formulas
* Shelf-life
- Softness
- Microbial
* Water binding
* Specific xylanases
* Green labeling
- Oxidants
- Emulsifiers
* Frozen dough
- Long-term stability without
rancidity

* Color (brightness)
- Flour
- Bread crumb
* Browning
- Microwave products
* Taste
* Health
- Fibre-enriched products
- Protection of micro-nutrients
- Celiac disease
- Glycemic Index
- Phenolic components
* Egg replacement
* Mycotoxin degradation

amide values, whereas yeast fermentation reduces them.
The decomposition of the precursor asparagine by asparaginase, Innovase ASP, is an effective means to reduce the
acrylamide formation. The enzyme is active in a pH range of
5 to 8.5 and at 30 to 65 degrees C, hence in an optimum range
for most baking applications. In crisp bread trials Innovase
ASP reduced acrylamide to less than 25%, and in wafers Innovase ASP reduced it to about 10% of the original level.
Several oxidases have been proposed and are being used for
improving the baking properties of flour, in particular dough
stability and mechanical tolerance. The common principle
of most oxidases applied in baking is their action on monoor oligosaccharides or other glycosides, creating a carboxyl
group and hydrogen peroxides. The hydrogen peroxide then
acts as a non-specific oxidant, oxidizing available electron
donors in dough, including sulfhydryl groups. This results
in the creation or protection of dough-strengthening disulfide bridges. In addition, oxidation gelation of pentosans via
feruloyl residues may occur, increasing the water absorption.
An undesirable side-effect of the above oxidases is their action on unsaturated lipids, which creates an unpleasant offflavor. In particular, bakery items from frozen and sheeted
dough, such as croissants, may be severely affected. Therefore, the use of glyco-oxidases as a general flour-improving
enzyme is not recommended.
Sulfhydryl oxidase (SOX, EC 1.8.3.2) specifically oxidizes
sulfhydryl groups in protein and peptides. Hydrogen peroxide
is also formed in this reaction. But in relation to the number
of oxidized sulfhydryl groups, much less hydrogen peroxide is
formed by SOX than by glycoside oxidases.
In baking trials, SOX from S. cerevisiae showed good potential, in particular in applications involving lamination steps
and prolonged fermentation. Figure 3, (page 47) shows a com48

parison of glucose oxidase and SOX in steamed bread baking trials. Furthermore, a partial replacement of ascorbic acid
used as a dough stabilizer was possible. Steamed bread with
reduced ascorbic acid had a brigher crumb color. The reason
for this effect is not yet known. In butter croissants made from
frozen dough, no formation of off-flavor was noted, while
GOX-treated samples developed a strange smell.
In wheat or rye flour dough, ferulic acid contributes to the
mechanical stability by absorption of water and the stabilization of gluten. An excess of stability can result in a limited
volume yield during the bread-making process. As in other
hemicellulases, ferulic acid esterase is able to soften the xylan/gluten complex by the release of water from the gel and
by the breakdown of covalent linkages. Unlike the most often
used hemicellulases exerting an endo-1,4-ß-xylanolytic action on the xylan polymer, ferulic acid esterase cleaves the
side-chains between the galactose residue and the ferulic acid.
Both activities improve the expandability of the dough and
hence can be used to increase the volume yield.
The enzyme has a significant effect on the dough rheology.
When applied in the Alveograph, it was possible to achieve
a significant reduction of the powder/liquid (P/L) ratio while
the energy remained constant over a wide dosage range. At
prolonged resting times (120 minutes), the energy was close
to that of untreated flour even when the P/L was diminished
to 0.46 instead of the initial ratio of 0.66.
The extensibility of the dough could be increased by about
30%. Obviously, the enzyme is capable of partially hydrolyzing the linkages between gluten and arabinoxylan) and/or to
break down the pentosan gel, resulting in the release of water
from the gel, which is then available for gluten hydration
and softening. The enzyme also reduces the viscosity of flour
suspensions, such as wafer batters.
The potential reasons for future growth of the bakery enzyme market are summarized in Figure 4 (above). One of the
factors mentioned is the replacement of gluten. The rising
global wheat price increases the tendency to replace expansive wheat with high gluten content and good baking properties by cheaper wheat. The lack of gluten content and baking performance can at least partially be replaced by adding
functional ingredients such as enzymes.
The second position in Figure 4 is taken by the term "shelf
life," in this case comprising microbial stability as well as
crumb softness. Both are increasingly required due to the
continuing trends of bakeries merging to larger units with
centralized production, which means longer distances from
WG
factory to shop.
Dr. Lutz Popper is director of research and development, Mühlenchemie
GmbH & Co. KG, Ahrensburg, Germany. For further information, he
may be contacted at lpopper@muehlenchemie.com.
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May 2008 / World Grain / www.World-Grain.com

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