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

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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

  1. 1. Digital Re-print -May | June 2013Additives for flour standardisation- Part II:Additives other than enzymeswww.gfmt.co.ukGrain & Feed MillingTechnology is published six times a year by Perendale Publishers Ltd of the United Kingdom.All data is published in good faith, based on information received, and while every care is taken to prevent inaccuracies,the publishers accept no liability for any errors or omissions or for the consequences of action taken on the basis ofinformation published.©Copyright 2013 Perendale Publishers Ltd.All rights reserved.No part of this publication may be reproduced in any formor by any means without prior permission of the copyright owner. Printed by Perendale Publishers Ltd. ISSN: 1466-3872
  2. 2. The most commonly used materialto strengthen gluten is ascorbicacid, also called vitamin C. Thematerial itself is originally a reducing ratherthan an oxidizing agent, but it is convert-ed into an oxidative substance, namelydehydroxy ascorbic acid (DHAA), throughthe action of flour enzymes during doughpreparation. DHAA basically inactivatesthe glutathione molecules which breakdown the sulfur bonds between thegluten molecules (Grosch and Wieser,1999). With this action, dough mixingresults in sulfur bond protection withoutexcessive breakdown, which in turn leadsto dough with desired structure.Pure ascorbic acid is added to the flour inmills at rates of typically 0.5-3 grams per 100kg of flour. This dosage may go up to 6-10grams per 100 kg in very weak flours or forweakening applications like frozen dough.Ascorbic acid is mainly produced by com-plex biochemical processing of glucose andsold as powder with different granule sizes.There are also natural sources for ascorbicacid, for instance acerola fruit powder, butthese are too expensive compared to thesynthetic ones.Potassium bromatePotassium bromate as a strong oxi-dative is still used as flour improver inmany countries in the world. The verylong lasting effect of bromate startslater than the effect of ascorbic acid andallows easier processing of the dough.Bromate creates new disulfide bondsresulting in more resistant doughs butit also oxidizes glutathione and henceprevents gluten weakening, just likeascorbic acid but without the help ofthe flour’s enzymes.Usage of bromate in flour industryis prohibited in the EU and many othercountries because of the health con-cerns and its unstable/fire-acceleratingnature.AzodicarbonamideAzodicarbonamide (ADA) is utilizedin flour industry because of its oxidativeaction. Its dosage is similar to ascorbicacid (with a recommended maximumof 45 ppm), but the dosage tolerance is low,so even a slight over dosage may result inbucky doughs and rough bread surfaces. It isa flammable material and its usage in food-stuff is not permitted in the EU and severalother countries.OthersOther than the ones stated above, thereare many oxidative materials and oxidationprocesses utilized throughout the world.Chlorination, usage of peroxides, iodates,persulfates, cystine and oxidative enzymesare some of these. All of these methods dif-fer by their effects on flour/dough, and theirpace of action.Dough relaxation, softening,reductionDough with ‘short gluten’ (low extensibil-ity) is hard to process. In addition to this, gasproduced during fermentation will not be ableto expand the dough sufficiently and hencethe volume of the end product will be small.Furthermore, for products like biscuits, crackersand wafers, the optimum processing condi-tions can be reached when gluten structure isweaker than normal. In these situations, reduc-tive materials are used to break the disulfidebonds and provide gluten with more flexibility.CysteineL-cysteine, a sulfur-containing amino acidfound in diverse proteins, breaks down thedisulfide bonds between and within glutenmolecules and becomes attached to thebond forming regions. This prevents glutenfrom getting stiff, and a mobile, flexible butstill coherent structure is secured. This effectseems to be the opposite of ascorbic acid’s,but actually they seem to complement eachother in some processes. This synergy isespecially used in frozen dough processes:Ascorbic acid provides the necessary fer-mentation stability whereas cysteine givesextensibility to gluten strands which haveshorten because of freezing.OthersInactive yeast preparations are rich inreducing material, but their dosage (500 –5,000 ppm) and price are relatively high,as compared to cysteine. Levels of otherreducing agents like sodium metabisulfiteand sulfur dioxide which are used as doughsoftening agents in biscuit and cracker pro-duction are limited to 50 ppm. This amountis not sufficient to observe a softening effectin strong flours. Furthermore, many coun-tries require declaration if the concentrationof residual sulfur dioxide exceeds 10 ppmTable 1: Suggested emulsifiers with potential use in baking applicationsEmulsifierCommonabbreviationHLB Application and benefitAcetyl esters of monoglycerides AMG 2.5-3.5 Whipped cakes, volumeCalcium stearoyl lactate CSL 7-9 Bread, shelf-life, volumeDiacetyl tartaric esters of monoglycerides DATEM 9.2 Bread, shelf-life, volumeEthoxylated mono- and diglycerides(polyglycerates)EMG 12-13High-fibre bread; shelf-life(combined with monoglycerides)Glycerol monostearate (non self-emulsifying) GMS 3.7 Shelf-lifeGlycerol monostearate (self-emulsifying) GMS 5.5 Shelf-lifeLecithin LC 3-4 Shelf-life, dough propertiesLactyl esters of monoglycerides LMG 3-4 Whipped cakes, volumeMono- and diglycerides MDG 2.8-3.8 Bread, cakes, cookies, volumePolyglycerol ester PGE 12-13 Whipped cakes, volumePropylene glycol monostearate PGMS 1.8 Whipped cakes, co-emulsifierPolysorbate 60 PS 60 14.4 Whipped cakes, co-emulsifierSuccinyl monoglyceride SMG 5-7 Yeast leavened baked goods; volumeSorbitane monostearate (e.g. SPAN 60) SMS 4.7-5.9 Whipped cakes, volumeSodium stearoyl lactate SSL 18-21 Bread, shelf-life, volumeSucrose esters SUE 7-13 Bread, cake, volumeAdditives for flour standardisation -Part II:Additives other than enzymesby Lutz Popper, Mühlenchemie GmbH & Co. KG, GermanyGrain&feed millinG technoloGy12 | may - June 2013FEATURE
  3. 3. in the final product. Figure 1 compares theeffect of cysteine and inactive yeast on theextensibility and resistance towards exten-sion in a standard wheat flour dough.EmulsifiersEmulsifiers are polar molecules that caninteract with many constituents of Emulsifiersthat interact with gluten during mixing processstrengthen the bonds between protein chains,but they also provide a lubricating effect thatallows the chains to slide over each other eas-ily. They are involved in the stabilisation of thegas bubbles in dough by binding to the bound-ary layers. As a result, dough elasticity, ovenrise and volume increase, and the crumb poresize reduces. The bakers will note an increasein the practical water absorption, although thedough rheological measurements may notconfirm this percep-tion. Other emulsifiersstrongly interact withthe starch delaying ret-rogradation and stalingand thus provide breadwith improved andprolonged softness andfreshness. Some havepotent foaming abilitybecause of their sur-face-active nature andare used as whippingagents for sponge cakeand the like. They ease the mixing of waterand fat and hence improve fat dispersion inbakery products that contain larger amounts offat, such as biscuits, or in liquid systems such aswafer batters. They also decrease the amountof necessary fat, contributing to cholesterol,calorie and cost reduction.LecithinLecithin is an emulsifier which has beenused in bakery products for a long time. Onceegg yolk was used as the source of lecithin,but nowadays concentrated lecithin obtainedfrom soy beans, canola or sunflower seedsis used. The most obvious benefit of lecithinis to lower the stickiness of the dough andimprove its machinability. Other than this,lecithin softens the crumb due to its interac-tion with starch. But its effect on volume isless than that of its synthetic counterparts.The dosage of lecithin is about 30-150 g per100 kg of flour (0.03 – 0.15 %). Low dosagesincrease the processing quality of the dough,whereas high dosages increase dough stabilityand fermentation tolerance, improve crumbstructure and prolong shelf life.Mono- and diglyceridesThese molecules are formed by breaking-off fatty acids from edible fats and oils. Theforms that are preferred as flour improverare the ones that prevent staling best. Thisproperty is found in linear saturated fatty acidsthat interact best with starch, and the mosteffective of them all is glycerol monostearate.The dosage starts at 0.05 percent and maygo up to one percent, especially in high-fatproducts.Diacetyl tartaric esters of mono-and diglycerides (DATEM)DATEMs currently are the most effectiveemulsifiers for bread volume. They are variousmolecules formed by esterification of mono-and diglycerides (obtained from edible oils)with mono- and diacetyl tartaric acid. Someof these molecules are more active than theothers (Köhler, 1999), but the effect of themixture is better than any single type of pureemulsifier.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 consistencyGrain&feed millinG technoloGy may - June 2013 | 13One of these flours has the desired quality.Aqua-Inject and Farinograph®-E can tell which one.The Brabender®Aqua-Inject is the perfectaddition to the Brabender®Farinograph®-E:Together they determine the rheologicalproperties of dough easier, faster and moreaccurately.■ Automated, computer-controlled water dosing■ Electronically regulated water temperature■ Utmost reproducible dosing andmeasurement accuracy■ Work without glass burette for more safetyBrabender®technology optimises the quality of yourraw materials and ensures your success.Brabender®GmbH&Co.KG · www.brabender.comAqua-Inject_210x148_GB.indd 1 29.05.2013 12:02:25FEATURE
  4. 4. but much lower dosages are used actually becauseof the high prices. We mentioned that the effectof lipolytic enzymes is comparable to emulsifiers.Recent studies are focused on producing carboxylesteerases that may reduce DATEM usage, orreplace it completely.Sodium and calcium stearoyllactylate (SSL and CSL)These emulsifiers are formed by theesterification of stearic acid with lactic acid.They act like DATEM, with a slightly weakereffect on dough stability and baking vol-ume. On the other hand, they are moreeffective in preserving the crumb softness.Furthermore, they are more suitable forbakery products that require a softer crust.Other emulsifiersOther than the ones stated above, thereare many more to be used in high-fiber prod-ucts, cake bases etc. The distinctive propertyamong them is the HLB value (Hydophilic-Lipohilic Balance). This value shows if theemulsifier displays a more hydrophilic orlipophilic character. Emulsifiers for high breadvolume yield rather have an HLB of 7 orhigher, while emulsifiers that improve the shelflife of the crumb softness exert a lower HLB,probably because they have to be able tointerfere with the non-polar interior of starchhelices. Table 1 provides a list of commonemulsifiers used in baking applications.Acidifiers and acidity regulatorsWith germination, high amounts of amy-lase are formed in grain. This enzyme workslike amylase added to the flour, but hasa stronger impact on lowering the FallingNumber (FN). If there is too much cerealamylase, the baking properties are negativelyaffected and the FN is too low. To restoregood baking properties, the dough may beacidified by natural lactic acid fermentation,resulting in a sour dough. This prevents thecereal enzymes from finding the optimumconditions and hence their activity decreases.But the taste and aroma developed duringacidification of the dough may not be wellreceived by everyone. Moreover, this proc-ess takes a long time. Other than naturalacidification, agents that are allowed infoodstuff, like fruit acids, salts of these acids,carbonates and phosphates may be used. Bycareful adjustment of these, the pH range(acidity) of the dough may be altered to alevel where the enzymes cannot work opti-mally. Most preferred of these additives arethe ones that keep the pH value at a desiredlevel regardless of the chemical changes inthe dough, called buffering agents. A typicaldosage is 50-200 grams per 100 kg of flour.It should be kept in mind that phosphatesand carbonates add to the ash content offlour. For sprout-damaged wheat, it is advisableto lower the extraction of enzyme-rich outerlayers of the kernels (that is, to decrease themilling yield) and produce a whiter flour thatallows addition of ash-increasing improvers.BleachersEven though customers are getting moreand more aware of the fact that darker milledflours 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, namelylutein, can be achieved with oxidative materials.Soy FlourThe best-known legal material for this applica-tion is enzyme-active soy flour. A clearly visibleeffect can be achieved at dosages around 0.5percent. There are two types of enzyme-activesoy flour in the market: deoiled and untreated.The bleaching effect is related to the lipoxygenaseenzyme in soybeans. Deoiled soy flour may havelost 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 bittertaste because of the enzyme urease.Because the soy flour’s bleaching effect isdue to an enzymatic reaction, the bleachingonly starts after contact with water, that is,during dough mixing.Powerful oxidativesBenzoyl peroxide, potassium bromate andtheir derivatives cause bleaching because of theirpowerful oxidative effects. Added at dosages of5-10 g per 100 kg, the effect of benzoyl perox-ide starts during storage of flour and the processis completed in about 1-3 days. These chemicalspose health risks by undesired residues andreaction products remaining in the final food orat least because of their inflammable, fire-accel-erating or even explosive nature. Furthermore,their usage in food is not permitted in the EUand in several other countries.Other agentsThe colour lightening effect on crumb experi-enced with the usage of ascorbic acid, emulsifiersand some enzymes is mostly a physical illusion.Using these improvers, one can have smaller andmore evenly distributed pores which cast lessshadow and therefore the crumb seems whiter.Using lipases also may contribute to a bleachingeffect provided that there is enough of oxygen inthe dough. The unsaturated fatty acids producedby lipase are converted to hydroperoxides by theflour’s own lipoxygenase, and these molecules inturn bleach carotenoids.Vital wheat glutenVital wheat gluten is produced by separatingthe water-insoluble proteins of wheat flour fromthe starch and soluble materials by a thoroughwashing process with water and drying of theresulting wet gluten. The material obtained viathis process consists of around 80 percent glu-ten plus some remaining starch, lipids and non-starch carbohydrates (Pomeranz, 1988). Whenadded to the flour, vital wheat gluten increasesthe protein strength. This effect is easily detectedwith the help of flour analysis equipment like theAlveograph or the Extensograph.The properties of gluten added from outsideare different from those of native gluten. Thedifference that can be observed by determiningthe water absorption and rheological properties,resulting from partial denaturation of the proteinduring the drying process. Because of this, aproper drying practice is the most importantfactor in preserving the function of vital gluten.Some manufacturers do not worry about keep-ing the quality of the protein, because vital glutenis sometimes still considered as a byproduct ofstarch production. Using this low quality vitalgluten increases the protein content of the flour,but does not improve the gluten properties.The water absorption capacity of added vitalgluten is lower than that of native gluten. A ratioof 1.3-1.5 parts of water per one part of vital glu-ten can often be observed, while this ratio goesup to 2.5-3 parts of water per one part of nativegluten in flour. Also the structure of vital glutenbecomes shorter because of the drying process.Because of this, softer wheat varieties are moresuitable for producing valuable vital gluten.The colour of gluten is also an importantcriterion in the market. Vital gluten mostly has agrayish tone that will also contribute to colour offlour. This is not a desired quality though; brightwhite or yellowish tones are preferred in flourindustry. The colour is affected by the wheatvariety, extraction and drying methods.ServicesMühlenchemie’s mission and practical knowl-edge lie in selecting and combining the individualraw materials described. The optimum composi-tion brings about synergistic effects. Since wheatqualities fluctuate, Mühlenchemie helps mills toproduce flours with consistent baking qualities.The samples of flour sent in by the mills aresubjected to a rheological analysis in the compa-ny, and the results are used to develop specificcompounds for each customer. Baking trials arethen carried out to test the flour improvers forfunctionality before they are offered to the millas Alphamalt.Besides customized products, Mühlenchemieoffers whole systems. The EMCEbest WA seriesincreases the water absorption capacity ofdoughs, and thus the yield, and results in a moresucculent crumb and a longer shelf life. TheEMCEgluten Enhancers can save on vital wheatgluten at 1/10 of its usage level, strengthen weakflours and make it possible to use compositeflours.Mühlenchemie offers mills further support intheir daily work in the form of seminars, labora-tory equipment and technical training coursesand helps with the quality control and improve-ment of flours on the spot.More inforMation:Website: www.muehlenchemie.deThe first part of this article, which dis-cusses enzymes and flour standardisa-tion, is in the March/April 2013 issueof Grain and Feed Milling Technology.It is also online at www.gfmt.co.ukGrain&feed millinG technoloGy14 | may - June 2013FEATURE
  5. 5. www.gfmt.co.ukLINKS• See the full issue• Visit the GFMT website• Contact the GFMT Team• Subscribe to GFMTA subscription magazine for the global flour & feed milling industries - first published in 1891INCORPORATING PORTS, DISTRIBUTION AND FORMULATIONIn this issue:• Additivesfor flourstandardisationPart II:Additives other thanenzymes• High efficiencyelevatorbuckets:modern vstraditionaldesign• Feed focusPoultry• Assessingnutritional valuewith NIRMay-June2013• ‘Kill step’validation oflow-moistureextrusion• Adding value tofeed millingwith profit-oriented feedformulation• Pest controlacross the supplychainfirst published in 1891This digital Re-print is part of the May | June 2013 edition of Grain & FeedMilling Technology magazine. Content from the magazine is available to view free-of-charge, both as a fullonline magazine on our website, and as an archive of individual features onthe docstoc website.Please click here to view our other publications on www.docstoc.com.To purchase a paper copy of the magazine, or to subscribe to the paper edi-tion please contact our Circulation and Subscriptions Manager on the linkadove. INFORMATION FOR ADVERTISERS - CLICK HEREArticle reprintsAll Grain & Feed Milling Tecchnology feature articles can be re-printed as a 4 or 8 page booklets (thesehave been used as point of sale materials, promotional materials for shows and exhibitions etc).If you are interested in getting this article re-printed please contact the GFMT team for more informa-tion on - Tel: +44 1242 267707 - Email: jamest@gfmt.co.uk or visit www.gfmt.co.uk/reprints

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