Flour Treatment for Specific Applications

By : The Future of Flour Book 

A. Steamed Bread

1. Introduction

Although they differ in details, steamed breads from various regions have several properties in common, for instance the lack of stabilization by a firm crust (in contrast to baked bread), a very fine crumb structure, and a mild, almost bland taste. 

This can be considered an advantage because of the absence of acrylamide and the possibility of combining the steamed bread with various fillings and dishes.

Since little or no salt is normally used, the dough is very extensible, but the stability of the finished, steamed product is also reduced. 

This is a special challenge to additives such as enzymes, ascorbic acid and other flour improvers.

Fig 159 : Basket for traditional steaming (source: H. Moegenburg, Muehlenchemie Asia Pte. Ltd.)

In the laboratory, steamed bread can be prepared in the traditional way – in baskets placed on woks containing boiling water (Fig. 159), stainless steel pots placed on a fire or electric hotplate, or in stainless steel steam chambers (Fig. 160). For the following investigations a steam chamber was used.

Fig. 160 : Stainless steel steaming chamber

Tab. 95 : Flour quality for steamed bread trials

Furthermore, flour with normal properties without any obvious quality problems was used. It fell into the flour quality range usual for steamed bread (Tab. 95). 

The course of the core temperature during 265 steaming is significantly lower than during baking (Fig. 161). 

Fig. 161 : Core temperature of baked buns and steamed bread

This has to be taken into account if ingredients coated with fats or emulsifiers or pure fat or emulsifier powders are used, and also if enzymes that have a high inactivation temperature, such as bacterial amylase, are included. 

Whereas the former would not dissolve readily, the latter would survive the curing process and cause damage in the final product.

2. Enzymes

2.1. Amylases

Amylases affect the volume yield and crumb softness of the steamed bread. Fig. 162 shows the effect of adding pure fungal α-amylase with 5,000 SKB/g. 

The volume yield increased by almost 25%, displaying a maximum at 250 ppm (equal to 1,250 SKB per kg of flour).

Fig. 162 : Effect of α-amylase with 5,000 SKB/g (Alphamalt VC 5000) on the size of steamed bread. The volume yield per 100 g of flour was 300, 325, 369 and 351 mL respectively (from upper left to lower right).

2.2. Hemicellulases

Not unexpectedly, the positive properties of hemicellulases, described in Flour Treatment : Enzymes, were also observed in the preparation of steamed bread. 

For instance, a hemicellulase from Aspergillus niger (Alphamalt HCC) achieved a volume increase similar to that of amylase (Fig. 163). 

At the same time the pore structure became much finer (not shown).

Fig. 163 : Effect of hemicellulase on the size of steamed bread. The volume yield per 100 g of flour was 300, 382, 373 and 373 mL respectively (from upper left to lower right)

2.3. Glucose Oxidase

The enzyme glucose oxidase (GOD) converts glucose into gluconic acid while oxidizing water into hydrogen peroxide, an oxidizing agent, as described in Oxidation and Flour Maturation. 

The reaction requires oxygen, which is readily consumed by yeast and some chemical reactions at the very beginning of the dough preparation process. 

This means that the effect of GOD is often only perceptible on the surface of the dough or the baked product (dryer dough surface, stabilized structure), while the volume yield is hardly affected. 

Most probably due to the specific dough development process often used in the preparation of steamed bread, the GOD has a better supply of oxygen. The effect on volume yield is therefore measurable. In our example the improvement was about 10% (Fig. 164). 

Fig. 164 : Effect of glucose oxidase on the size of steamed bread. The volume yield per 100 g of flour was 300, 317, 334 and 321 mL respectively (from upper left to lower right).

One further effect is always mentioned by the bakers: the doughs have better machinability because of reduced stickiness.

2.4. Lipase

Lipase is yet another miracle enzyme, underestimated for a long time. The enzyme converts lipids into di- and monoglycerides, i.e. emulsifiers (see in Flour Treatment : Enzymes ). 

Especially after extensive kneading, lamination or long fermentation processes, a dramatic effect on dough stability and volume yield can be noted. 

In the example shown in Fig. 165, the increase was a net 70%. Since it is highly dependent on processing conditions, this effect cannot be reproduced with all dough preparation methods.

Fig. 165 : Effect of a commercial enzyme preparation containing a specific lipase on the size of steamed bread. The volume yield per 100 g of flour was 300, 447, 477 and 512 mL respectively (from upper left to lower right; colour differences were due to a rising thunderstorm).

Development of the dough by sheeting promotes the beneficial effect of lipase. This is probably due to a more extensive exposure to atmospheric oxygen. 

Endogenous lipoxygenases prefer to react with free unsaturated fatty acids rather than with unsaturated fatty acids bound to the glycerol backbone. 

Lipolysis exposes the fatty acids to the action of lipoxygenases which, in the presence of sufficient oxygen, are converted into hydroperoxides; these in turn react with components of the flour. 

In addition to dough strengthening, a bleaching effect occurs due to the oxidation of flour carotenoids. Since lipases are specific to the type of fatty acid present in the triglyceride, not all lipases are suitable for improving steamed bread.

Fig. 166 : Effect of specific lipases (Tigerzym 01, LP 12066), glucose oxidase (Gloxy 7082), α-amylase (VC 5000) and hemicellulase (HCC) on the volume yield of steamed bread

Fig. 166 and Fig. 167 summarize the effects of various enzymes on volume yield. The data are taken from two sets of trials, so there are two different references. 

Tigerzym 01 and LP 12066 signify two different lipases; Gloxy 7082 stands for glucose oxidase from Aspergillus niger; VC 5000 is 5,000 SKB/g α-amylase from A. oryzae; HCC, HCE and HCH are hemicellulases from A. niger, Thermomyces lanoginosus expressed in A. niger and from Bacillus subtilis respectively; 269 C 132 is a cellulase from a Trichoderma species, and BG 31 is a β-glucanase from A. niger. 

By combining several enzymes, additive effects resulting in even larger volume yield can be achieved (Tigerzym 02). Pure lipase, Tigerzym 01, served as an internal standard for both sets of trials.

Fig. 167 : Effect of specific lipases (Tigerzym 01), hemicellulases (HCE, HCH), cellulase (C 132), β-glucanase (BG 31) and an enzyme combination (Tigerzym 02) on the volume yield of steamed bread

2.5 Oxidation

Ascorbic acid is known to improve dough stability, crumb structure and volume yield in baking. Would it have comparable effects in steamed bread? 

Fig. 168 answers part of this question, showing the volume yield when ascorbic acid is combined with α-amylase in normal and long fermentation (1 h and 2 h respectively). 

A distinct maximum as a function of ascorbic acid concentration appeared in all the trials. Amylase caused a shift towards higher concentrations, which is analogous to baking. 

The exact amount necessary to achieve a maximum depends on various factors such as the recipe, process, and flour quality.

Fig. 168 : Effect of ascorbic acid on the volume yield of steamed bread

2.6 Emulsifiers

The number of emulsifiers used in baking is still increasing. In our investigations we used the most common ones, i.e. SSL, CSL, DATEM and mono/diglycerides. The dosage was in the typical range for baking applications, i.e. between 0.1 and 0.5% on flour. 

While DATEM had the best volume yield (Fig. 169), the appearance and pore structure of the buns were not satisfactory. The best overall result was achieved with SSL, which produced good volume, a regular shape, a fine, even and bright pore structure and prolonged crumb softness

Fig. 169 : Effect of emulsifiers on the volume yield of steamed bread

Trials with sucrose esters also resulted in improved volume (not shown), but the overall properties were inferior to SSL and the cost was much higher.

B. Rye and High-Fibre Flour

In Northern Europe high-fibre bread has a long tradition. Rye flour contributes a large proportion of the dietary fibre in all countries around the Baltic Sea. 

Rye per se does not have a higher fibre content than wheat, but the dark flours used for most types of rye or mixed flour bread provide up to 3 times as much fibre as standard wheat flour (Fig. 170).

Fig. 170 : Composition of wheat and rye and some typical flours (data from Souci et al., 2000)

A large variety of breads are made with rye flour (Fig. 171). Due to the lack of a gluten network, the volume yield is comparatively low if a large proportion of rye flour is used.

Fig. 171 : Selection of rye bread

Acceptable processing conditions and sufficient dough stability can only be obtained by acidification, either through sour dough or with acidifiers such as lactic acid, acetic acid or fumaric acid.

Ascorbic acid as a maturing agent is only used in mixed flour bread. Sour dough fermentation reduces the amount of available simple sugar, improving the glycemic index further.

1. Enzymes for Wheat and Rye "Volume" Bread

1. 1 Amylases

Although bread with a high fibre content already has a lower staling rate due to the higher water absorption, amylolytic enzymes of microbial or cereal origin are able to improve this even further, particularly if grains with low intrinsic enzyme activity (i.e. high Falling Numbers) are used (see in  Chapter Viscocity of Dough Rheology as a Function of Flour Treatment).

1. 2 Hemicellulases

Pentosanases and glucanases affect the hemicelluloses of wheat and rye (Fig. 172). Pentosans consist of two fractions, one of which is water soluble, while the other is not. 

Fig. 172 : Effect of glucanase on the structure of rye kernels. Left: untreated, right: treated with β-glucanase.

Hydrolysis of the water-insoluble fraction results in smaller, water-soluble fragments (solubilized) which absorb more water.

When soluble or solubilized pentosan is hydrolyzed, water is released from the gel. Some pentosanases only act on one or the other pentosan fraction, while others are less specific.

1. 3 Non-Specific Pentosanase

Secabon, a standard wheat flour treatment pentosanase from a Trichoderma species, acts on both soluble and insoluble pentosans. At a suitable concentration the water absorption will first rise, improving machinability. 

Later in the process, water will be released from the pentosan gel through the continuing hydrolysis of soluble and solubilized pentosans (Fig. 173). 

Fig. 173 : Effect of Secabon on the viscosity of wheat pentosans

This increases the availability of water and thus softens the dough structure (better volume yield), retarding and reducing starch retrogradation.

1. 4 Dough "Drying" with Specific Pentosanases

If the doughs are already quite slack, a very specific xylanase which acts almost solely on the insoluble pentosans may be useful: it increases water absorption and thus results in dryer and more stable dough. 

Picture shows the effect of such a xylanase on a wheat flour type 550 in the Farinograph. The effects may be even stronger in rye and dark wheat flour.

1. 5 Proteases

Some baking properties of rye flour and dark wheat flours, for instance the volume yield, can be improved by adding vital wheat gluten. 

It does not have exactly the same functionality as native gluten (See in chapter Vital Wheat Gluten). Some of its natural behaviour can be recovered by protease. 

It can be used to improve the structure of the protein if the bread-making process is well controlled, taking into account the time-dependent action of the enzyme. Purified fungal proteases will be preferable due to their comparatively mild (specific) action at acidic pH.

1. 6 High-Extraction Wheat Flour

In addition to rye, bread from dark wheat flour (high extraction) or whole wheat meal is also fairly common, especially in Germany but also in some other northern European countries. 

Its specific volume is superior to that of rye bread. Sour dough or acidification is not necessary but sometimes used, in particular for dark varieties of bread. 

Flour treatment is not unlike that for white wheat flour, i.e. oxidation or ascorbic acid and enzymes (amylases, hemicellulases).

1. 7 Crispbread

Fig. 174 : Examples of crispbread

Crispbread (Fig. 174) is a speciality from Scandinavia. Most types are made from a rather liquid yeast sponge dough (dough yield about 190%) which is sheeted, or rather spread, after 2 h fermentation into a layer 2.5 mm thick. This is followed by another fermentation of 30 - 60 min. 

Major challenges are the sticky dough and the instability of the sensitive sheeted foam, as well as sufficient energy supply to the yeast without impairing the taste and colour of the final bread. 

The energy necessary for dehydration is a further important factor, as the dough moisture has to be reduced from about 50% to below 6%.

The flour treatment for crispbread can be summarized as follows:

• Ascorbic acid: little or none

• Amylase: for browning and fermentation

• Hemicellulases and cellulases: to decrease water addition and avoid checking (hairline cracks)

• Protease to avoid checking.

Amylases are able to provide a constant supply of energy to the yeast. 

While a given sugar addition can result in vigorous fermentation at the beginning followed by a sudden stopping of yeast activity once the sugar resources are finished, the amylases continue to produce fermentable sugar in the same measure as the yeast continues its fermentation. 

Instead of collapsing dough due to over-fermentation, a constant volume increase can be achieved, with its maximum at the beginning of the baking process.

Some pentosanases are able to increase the amount of bound water at the beginning of their action, while in the long run water will be released again. This is a property that can be exploited particularly for the crispbread process. 

During pre-fermentation and dough processing, good stability with dry surfaces is required, whereas after a further fermentation time the water retention should be low to improve the drying behaviour.

Oxidases mainly affect the surface of the dough. Only in a small mixer such as the Farinograph mixer do they have a visible effect on the dough rheology (picture below), because the surface to volume ratio is large enough to permit the access of sufficient oxygen to the system. 

In crispbread production they reduce the stickiness of the dough sheet, improving its processing behaviour.

Effect of glucose oxidase on the Farinogram

1. 8 Biscuits and Crackers

Biscuits and crackers offer yet another possibility of incorporating high-fibre flour. Whereas rye is not very common for crackers or biscuits, wholemeal is. In this case, distribution is not limited to Northern Europe. 

Typical examples are biscotti integrale (biscuits) or crackers integrale from Italy and granola biscuits from England (Fig. 175). 

Fig. 175 : Wholemeal and high-fibre biscuits (and crackers)

Here again, Secabon, a hemicellulase with broad activity on pentosans, is very useful. It improves the chewing properties, making the bite shorter, but it also improves the properties of the return dough, since it counteracts the drying out of the dough during processing.

C. Noodles and Pasta Flour

Improvers for noodle flour include:

• vital wheat gluten;

• emulsifiers;

• bleaching agents;

• colorants, in particular ß-carotene;

• ascorbic acid;

• hemicellulase and

• lipases.

Enzymes with xylanolytic, glucanolytic and particularly lipolytic activities have proved extremely useful in the production of noodles and instant noodles from soft and hard wheat. They offer many advantages, for instance:

• reduced tendency to bend;

• increased firmness of the cooked noodles;

• enhanced overcooking tolerance;

• reduced oil uptake of fried instant noodles;

• reduced drying time;

• improved surface appearance and mechanical stability of dried noodles,

• reduction of raw material costs.

The addition of a lipolytic and xylanolytic enzyme compound (Pastazym) improves the tolerance of noodles made from soft and hard wheat flour to overcooking, as shown in Fig. 176. With 10 g of the compound per 100 kg flour, the resistance to compression increases by almost 30% for over-cooking conditions (10 min).

Fig. 176 : Improvement of overcooking tolerance

The uncooked noodles already show improved stability (Fig. 177). This results in improved handling properties such as better resistance to mechanical stress (e.g. packaging) and reduced stickiness.

Fig. 177 : Firmness of fresh, uncooked noodles with the addition of a lipolytic and xylanolytic enzyme compound

To create the optimum texture of instant noodles is a major challenge: On the one hand dry noodles have to rehydrate as quickly as possible, and on the other they must have a homogenous texture without overcooked outer layers and hard cores. 

Furthermore, they should not become soggy through extended exposure to hot water. As Fig. 178 shows, Pastazym improves the firmness of cooked instant noodles while the rehydration properties remain constant. The result is a firm bite without a hard, dry core texture.

Fig. 178 : Firmness of cooked instant noodles made from soft wheat with the addition of a lipolytic and xylanolytic enzyme compound

The colour of raw noodles tends to deteriorate rather quickly. With the enzyme compound the darkening is reduced, and the noodles show improved whiteness even after 24 h (Fig. 179). 

Fig. 179 : Colour of fresh, uncooked noodles with the addition of a lipolytic and xylanolytic enzyme compound

The difference in L* between the reference and the noodles with 10 g Pastazym is about 3. The human eye can detect differences exceeding L* = 1. The colour difference persists after cooking (Fig. 180).

Fig. 180 : Effect of Pastazym on the colour of dry and rehydrated noodles made from wheat flour. A: Dry noodles, reference; B: with Pastazym; C: Cooked noodles, reference; D: with Pastazym

1. Other additives

Tab. 96 : Soft wheat noodle extrusion trials (double spiral noodles) with various additives

Tab. 96 is a summary of noodle extrusion trials with soft wheat flour using various additives. Although hemicellulases have the potential to reduce the viscosity of the extruded noodle or pasta dough or to reduce the water addition if added in very large amounts, this did not show at the chosen dosage. 

Surprisingly, they did not modify the appearance or texture of the finished products even at very high dosages.

 

In sheeted noodle production, hemicellulases improve sheetability because they soften the dough without weakening the protein.

 

Transglutaminase strengthens the protein, which should improve the cooking tolerance of noodles. The bite was indeed firmer, but the appearance of the cooked noodle did not improve as compared to the reference.

 

The addition of vital wheat gluten achieved the expected improvement in texture. A phospholipid-protected gluten resulted in better visual ratings.

 

An emulsifier compound of mono- and diglycerides and lecithin sprayed onto a carrier (Mulgaprot S1) was rated best. For many years Mulgaprot has been used successfully as a flour improver in Central European countries. 

Its use in tropical and subtropical areas is limited by the negative effects of elevated temperatures on particle size distribution.

 

Oxidizing agents and ascorbic acid also strengthen the protein, but they impair the processing properties of the dough. 

This may result in an irregular noodle structure with an increased tendency to checking. Furthermore, this strengthening cannot be detected in the finished product in the form of improved cooking tolerance.

D. Composite Flour

In most cases the use of non-wheat flours in mixtures with wheat flour results in a noticeable loss of volume and changed appearance (Fig. 181); the sensory attributes are also different. 

Fig. 181 : Structure of bread made from untreated wheat flour, alone or mixed with tapioca starch, rye flour or soybean flour (70 / 30%; upper left to lower right)

If the overall quality of goods baked from composite flour (taste and smell, chewing properties, appearance, shelf-life) is to approach that of pure wheat products, the wheat flour component of the composite flour must first be treated – although even then the amount of other flours that can be added is very limited. 

The well-known flour improvers potassium bromate and ascorbic acid have proved useful for this purpose. The dosage has to be adjusted to the particular wheat flour quality. As a rule it is between 20 and 50 ppm. To take the other flours into account seems to make little difference. 

If lipases are used in conjunction with soy flour, for example, there is no noticeable improvement in volume (Fig. 182), although this would be the case with wheat flour alone.

Fig. 182 : Bread made from composite flour (90/10) with defatted soybean flour (upper row) and toasted, full-fat soybean flour (lower row), using a lipolytic enzyme (from left to right 0, 60 and 180 ppm Alphamalt LP 12066)

Modern enzyme preparations also help to compensate for the loss of volume caused by using composite flour instead of wheat flour alone. Besides amylases, hemicellulases and also lipases can be used.

Fig. 183 : Effect of flour treatment on bread made from composite flour with defatted soybean flour, (70:30). 60 ppm ascorbic acid plus Powerzym 6000 (hemicellulase/amylase compound), 0, 75, 100 and 150 ppm on wheat flour (upper left to lower right)

Fig. 183 shows the effect of treatment with ascorbic acid and a baking enzyme on the structure of bread made from wheat flour with the addition of soy flour (70:30). 

Other additives commonly used in baking improvers, such as emulsifiers, improve the results still further. Fig. 184 shows the effects of various flour improvers on the volume of pan bread made from a composite flour consisting of CWRS

Fig. 184 : Effect of flour treatment on pan loaves made from composite flour (CWRS flour/cassava flour 85:15) in comparison with wheat flour alone (WF = wheat flour, CF = composite flour, AA = ascorbic acid, FAA = fungal α-amylase, ENZ = enzyme compound, EMUL = emulsifier, DATEM)

and cassava flour in comparison with CWRS flour alone. In this case a combination of ascorbic acid, enzymes and emulsifiers made it possible to restore the volume of the loaves almost completely up to a wheat/cassava ratio of 85:15. 

If the wheat flour used is less strong it will be necessary to add wheat gluten or reduce the proportion of non-wheat flour. The nature of the foreign cereal may also play an important role.

 

The effect of the emulsifiers GMS, CSL and lecithin, and also of pre-gelatinized starch, has already been described in Composite Flour.

 

There are no rules for such flour treatment. It has to be optimized in each case, depending on the composition of the flour and the baking properties of the wheat flour used. Reference has also been made to the use of potassium bromate and ascorbic acid as flour improvers in Composite Flour.

 

The wheat flour used should have optimum baking properties, and these can be achieved by suitable treatment with enzymes and oxidizing agents along with emulsifiers and waterbinding substances.

E. Flour Treatment for Biscuits, Crackers and Wafers

Whereas a high protein content and strong gluten are desirable properties in many bread processes, flours with little and weak gluten are preferable for durable baked goods. 

The tendency of dough to spring back after rolling and the undesirable formation of gluten lumps in wafer batters are the reasons for this requirement. 

Whether a flour with low and weak protein is available or not, the use of elasticityreducing agents (proteases, L-cysteine, glutathione, inactivated yeast, sodium metabisulphite) will have benefits at all stages of the process: the lamination will be more uniform; reduction of the thickness of the dough sheet can be performed faster and more reproducibly; relaxing periods for the dough sheet can be shortened or even omitted; the dough pieces will keep the shape given by cutting; shrinkage and bending in the oven and also the formation of hairline cracks (checking) are avoided. 

With suitable amylases, expensive 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. 

Fig. 185 : Effect of lecithin on the spread of cookies. left: reference; right: 1% liquid lecithin on flour (Courtesy of J. v. Wakeren, Caracas)

Emulsifiers, particularly lecithin (Fig. 185), but also mono- and diglycerides or DATEM, improve the spread of cookies and the regularity of biscuits and crackers. They can also be used to reduce fat in a recipe. Emulsifiers are usually applied at the bakery itself.

 

1. Biscuit and Cracker Applications

Tab. 97 : Biscuits baked with and without bacterial protease

Tab. 97 shows the recipes for simple hard biscuits made without and with bacterial protease. The last row compares the dimensions of the biscuits. 

As the length/width ratio shows (average of 25 biscuits), there is almost no difference between the length and width of biscuits with enzyme addition, whereas those without enzyme show shrinkage in one direction. 

Fig. 186 : Underside of hard biscuits baked without (top) and with bacterial protease (bottom)

Since the protease takes away most of the internal tension, the products are less inclined to bend during baking: the first row of Fig. 186 shows the underside of biscuits without protease; colouring occurred mainly at the margins, which were still touching the oven stone when the cookies became convex due to asymmetric protein shrinkage upon thermal denaturation. 

Biscuits made with protease remained flat and showed uniform browning (bottom row). This, too, is a common problem that can be observed with many commercially produced hard biscuits.

 

2. Wafer Applications

Batters for wafer production contain a large amount of water. A low viscosity and a uniform dispersion of all the ingredients is essential for even wafers with a homogeneous structure. 

Since the formation of gluten lumps during mixing can result in standstill of the machinery due to blocked tubes and sieves, or in uneven browning and reduced stability of the baked goods, the use of low protein flour is desirable, but may not be sufficient. 

Liquefying hydrolytic enzyme complexes are able to decompose any gluten present in a liquid batter, resulting in a uniform mixture with optimum flow properties. The viscosity reduction enables less water to be used in the recipe, and this in turn results in lower energy consumption for baking and a higher oven throughput. 

Such enzymes are most suitable for semi-continuous processes with batch times of at least 10 min, because the enzyme reaction needs some minutes to take effect.

 

We used the Amylograph at a constant temperature for a simple test to demonstrate the effect of a "wafer enzyme" (bacterial protease, hemicellulase) on the rheological properties of a liquid dough system (Fig. 187). 

Fig. 187 : Effect of a "wafer enzyme" on the viscometric behaviour of wheat flour batter (Amylograph, 30 °C)

Standard wheat flour for bread making was used in all the tests; 250 g flour was premixed with 330 mL of water in a Braun mixer for 1 min 45 s and then put into the reaction jar of the Amylograph, which was adjusted to a constant 30 °C. 

The wafer enzyme was added to one sample at 20 g per 100 kg flour before the start of mixing. Whereas the reference sample remained at almost the same viscosity for about 40 min, the enzyme caused an immediate viscosity drop. 

Furthermore, all the gluten strands were destroyed, which is evident from the definite shape of the curve. By contrast, the reference curve shows large fluctuations due to gluten lumps or strands adhering to the mixing tool of the Amylograph.

 

Fig. 188 : Viscogram of wafer batter with different proteolytic enzyme compounds and dosages (Brookfield Rotovisco, 25 °C)

Similar results can be obtained with other viscometric devices, e.g. the Brookfield viscometer (Fig. 188), although only the rotating rods of the Amylograph seem to be able to show the development – and disappearance – of gluten lumps.

 

In baking trials with a pilot-scale plant it was possible to control the water addition and thus the weight and density of the wafers with the help of the enzyme compound. 

Fig. 189 : Effect of water addition on evaporation costs and wafer density (energy costs: 0.15 e/kWh) 1. with wafer enzyme 2. no enzyme

This offers great economic advantages (reduced energy demand, higher throughput) and more freedom for product development (Fig. 189). Wafers of higher density are crisper and remain crisp longer because of reduced water absorption.

 

3. Replacement of Sodium Metabisulphite (SMB) in Cracker and Wafer Production

This powerful reducing agent (show in Reduction and Dough Softening) splits the inter-chain and intra-chain disulphide bonds of the gluten, causing an immediate fall in dough resistance (picture below) or batter viscosity. Sodium Metabisulphite is very cheap and easy to use.

Farinographs of German soft wheat flour without (left) and with 500 ppm Sodium Metabisulphite (right)

In many countries, therefore, Sodium Metabisulphite is still used in wafer and cracker production although it causes a sulphurous off-taste. 

Enzymes as an alternative to Sodium Metabisulphite improve the taste and have definite technical advantages, namely constant dough properties once the reaction is accomplished, including similar texture of return dough and fresh dough, the reduction of water addition to wafer batters and control of wafer density and stability (Fig. 189).

 

Fig. 190: Farinographs with sodium metabisulphite (SMB) or enzymes. A: proteolytic enzyme for liquid wafer batters; B: proteolytic biscuit and cracker enzyme; C: proteolytic, amylolytic and hemicellulolytic enzyme complex.

When tested in the Farinograph, both Sodium Metabisulphite and enzymes show a decline in kneading resistance (Fig. 190). 

The reaction of Sodium Metabisulphite occurs much faster, but probably due to the presence of atmospheric oxygen, some of the resistance is restored upon continued mixing, when disulphide bonds broken by Sodium Metabisulphite recover (upper right). 

The slower but persistent reaction of the enzymes results in minimum resistance, when all the substrate of the enzymes has been degraded.

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