Additives for flour standardisation - Part II: Additives other than enzymes

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                             May | June 2013
       Additives for flour standardisation
     - Part II: Additives other than enzymes
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     FEATURE




Additives for flour standardisation -

Part II:
Additives other than enzymes
by Lutz Popper, Mühlenchemie GmbH & Co. KG, Germany



T
       he most commonly used material             of 45 ppm), but the dosage tolerance is low,              Cysteine
       to strengthen gluten is ascorbic           so even a slight over dosage may result in                     L-cysteine, a sulfur-containing amino acid
       acid, also called vitamin C. The           bucky doughs and rough bread surfaces. It is              found in diverse proteins, breaks down the
material itself is originally a reducing rather   a flammable material and its usage in food-               disulfide bonds between and within gluten
than an oxidizing agent, but it is convert-       stuff is not permitted in the EU and several              molecules and becomes attached to the
ed into an oxidative substance, namely            other countries.                                          bond forming regions. This prevents gluten
dehydroxy ascorbic acid (DHAA), through                                                                     from getting stiff, and a mobile, flexible but
the action of flour enzymes during dough          Others                                                    still coherent structure is secured. This effect
preparation. DHAA basically inactivates               Other than the ones stated above, there               seems to be the opposite of ascorbic acid’s,
the glutathione molecules which break             are many oxidative materials and oxidation                but actually they seem to complement each
down the sulfur bonds between the                 processes utilized throughout the world.                  other in some processes. This synergy is
gluten molecules (Grosch and Wieser,              Chlorination, usage of peroxides, iodates,                especially used in frozen dough processes:
1999). With this action, dough mixing             persulfates, cystine and oxidative enzymes                Ascorbic acid provides the necessary fer-
results in sulfur bond protection without         are some of these. All of these methods dif-              mentation stability whereas cysteine gives
excessive breakdown, which in turn leads          fer by their effects on flour/dough, and their            extensibility to gluten strands which have
to dough with desired structure.                  pace of action.                                           shorten because of freezing.

    Pure ascorbic acid is added to the flour in   Dough relaxation, softening,                              Others
mills at rates of typically 0.5-3 grams per 100   reduction                                                     Inactive yeast preparations are rich in
kg of flour. This dosage may go up to 6-10            Dough with ‘short gluten’ (low extensibil-            reducing material, but their dosage (500 –
grams per 100 kg in very weak flours or for       ity) is hard to process. In addition to this, gas         5,000 ppm) and price are relatively high,
weakening applications like frozen dough.         produced during fermentation will not be able             as compared to cysteine. Levels of other
    Ascorbic acid is mainly produced by com-      to expand the dough sufficiently and hence                reducing agents like sodium metabisulfite
plex biochemical processing of glucose and        the volume of the end product will be small.              and sulfur dioxide which are used as dough
sold as powder with different granule sizes.      Furthermore, for products like biscuits, crackers         softening agents in biscuit and cracker pro-
There are also natural sources for ascorbic       and wafers, the optimum processing condi-                 duction are limited to 50 ppm. This amount
acid, for instance acerola fruit powder, but      tions can be reached when gluten structure is             is not sufficient to observe a softening effect
these are too expensive compared to the           weaker than normal. In these situations, reduc-           in strong flours. Furthermore, many coun-
synthetic ones.                                   tive materials are used to break the disulfide            tries require declaration if the concentration
                                                  bonds and provide gluten with more flexibility.           of residual sulfur dioxide exceeds 10 ppm
Potassium bromate
    Potassium bromate as a strong oxi-        Table 1: Suggested emulsifiers with potential use in baking applications
dative is still used as flour improver in                                                         Common
many countries in the world. The very         Emulsifier                                                          HLB          Application and benefit
                                                                                                 abbreviation
long lasting effect of bromate starts
later than the effect of ascorbic acid and
allows easier processing of the dough.                     Acetyl esters of monoglycerides          AMG         2.5-3.5        Whipped cakes, volume
Bromate creates new disulfide bonds                                 Calcium stearoyl lactate         CSL          7-9          Bread, shelf-life, volume
resulting in more resistant doughs but            Diacetyl tartaric esters of monoglycerides       DATEM          9.2          Bread, shelf-life, volume
it also oxidizes glutathione and hence                 Ethoxylated mono- and diglycerides                                    High-fibre bread; shelf-life
                                                                                                    EMG          12-13
prevents gluten weakening, just like                                      (polyglycerates)                                (combined with monoglycerides)
ascorbic acid but without the help of         Glycerol monostearate (non self-emulsifying)          GMS           3.7                  Shelf-life
the flour’s enzymes.                               Glycerol monostearate (self-emulsifying)         GMS           5.5                  Shelf-life
    Usage of bromate in flour industry                                                Lecithin       LC           3-4         Shelf-life, dough properties
is prohibited in the EU and many other                      Lactyl esters of monoglycerides         LMG           3-4          Whipped cakes, volume
countries because of the health con-
                                                                    Mono- and diglycerides          MDG         2.8-3.8    Bread, cakes, cookies, volume
cerns and its unstable/fire-accelerating
                                                                           Polyglycerol ester       PGE          12-13         Whipped cakes, volume
nature.
                                                            Propylene glycol monostearate          PGMS           1.8      Whipped cakes, co-emulsifier
Azodicarbonamide                                                             Polysorbate 60         PS 60         14.4     Whipped cakes, co-emulsifier
    Azodicarbonamide (ADA) is utilized                              Succinyl monoglyceride          SMG           5-7     Yeast leavened baked goods; volume
in flour industry because of its oxidative         Sorbitane monostearate (e.g. SPAN 60)            SMS         4.7-5.9        Whipped cakes, volume
action. Its dosage is similar to ascorbic                           Sodium stearoyl lactate          SSL         18-21         Bread, shelf-life, volume
acid (with a recommended maximum                                               Sucrose esters        SUE          7-13           Bread, cake, volume

12 | may - June 2013                                                                                                  Grain &feed millinG technoloGy
                                                                                                                                                 FEATURE


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




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Aqua-Inject_210x148_GB.indd 1                                                                                                                         29.05.2013 12:02:25
      Grain   &feed millinG technoloGy                                                                                                      may - June 2013 | 13
     FEATURE


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


14 | may - June 2013                                                                                                   Grain  &feed millinG technoloGy
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                                                                                      In this issue:
                                      •       Adding value to
                                              feed milling
                                              with profit-oriented feed
                                                                                  •     Additives
                                                                                        for flour
                                              formulation                               standardisation
                                                                                        Part II:
                                                                                        Additives other than
                                                                                        enzymes



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DOCUMENT INFO
Description: 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.