Faina de secara

7/27/2019 Faina de secara

1/14

Rye

Flo

ur

179

15.1 Introduction

Rye the Latin name is Secale cereale is stillgenerally regarded as the typical Germanbread cereal. Nevertheless, there is a continuousdecline in rye consumption. In the case of thisbread cereal, too, it is chiefly winter rye that isused for baking. Although over 90% of theworld's rye is grown in Europe, the cereal is byno means a uniform product. The main growingareas and breeding centres are in eastern,central and northern Europe, although rye isalso grown and bred in North America,Australia and other regions.

Generally speaking, the objectives of breedingcrop plants are to achieve and maintain yieldas an "agricultural value" and, where necessary,

to ensure good properties for a specific use asa "technological value". Taken together, thetwo values ultimately determine the marketvalue of a variety. This also applies to rye as abread cereal.

15.2 Yield as a Mark of Progressin Breeding

The breeding of rye took a tremendous stepforward with the introduction of hybrid20

varieties around 1970. The importance ofthis progress lay in the much greater yield ofthe hybrids as compared with pure breedsand the fact that this yield was largelyindependent of soil quality. Although thereliability of the yield depends on climaticconditions and is therefore subject to certainannual fluctuations, the possibilities ofincreasing the yield with hybrid varietiesremain constant. A further advantage inyears with poor weather and in unfavourablelocations is the hybrids' good resistance tosprouting.

Fig. 92 shows the development of varietiesover the past three decades and thesignificance of the hybrids for the FallingNumber as a criterion for evaluation.

15.2 Yield as a Mark of Progress in Breeding

15 Rye Flour

J.-M. Brmmer

21

Fig. 92: Falling Number levels for the rye varieties approved in Germany since 1977

20 Hybrid: offspring from two genetically dissimilar parents. Two organisms are crossed with different desirablecharacteristics with the premise that the offspring will possess more of the desirable characteristics.

179


2/14

180

Rye

Flo

ur

Yield is an important factor in all forms of crophusbandry.Rye is an interesting cereal from the point ofview of ecologically controlled and organicfarming because it shows its advantages inrespect of yield and yield stability even withextremely little use of agricultural inputs,including pesticides. For this reason rye andalso dinkel are sometimes regarded as the"health cereals".Further advantages of rye are that its proteinhas greater biological value for man than thatof wheat, that it is less susceptible to mould

including Fusarium than many wheatvarieties and that it is less inclined to formfusariotoxin.However, the subject of ergot should beconsidered in connection with rye. Possibledifferences in susceptibility to Claviceps

purpurae infections between the hybrid andpure breeds are still being discussed.Tab. 69 shows the rye varieties most widelygrown in Germany at present on the groundsof regional decisions and yield. Hybrid varieties

account for over 75% of the rye grown.

15.3 Objectives of Breedingin Respect of TechnicalSuitability for Processingas Bread Rye

The BSA 21 considers the following criteriaimportant for rating the suitability of rye forbread-baking:

Thousand kernel weight (TKW); Crude protein content (CPC); Peak Amylogram values for viscosity and

temperature; Results of the Falling Number test.

When assessing new wheat varieties the BSAcarries out baking trials: this is not the casewith rye. In contrast to the procedure forbaking wheat, the four criteria stated abovewere considered an adequate basis for describingthe suitability of new bread rye varieties forbaking when the present rating systems were

introduced. This was justified as long as a

sufficiently elastic crumb was the only qualityattribute to be achieved in rye bread, anattribute that was usually guaranteed byadequate enzyme levels in the greater part ofthe rye harvest.Rye grain Falling Numbers of about 100 to 120 sor higher corresponding to peak Amylogramtemperatures of about 63 C were considerednecessary to ensure this aspect of processingquality.

15.4 Rye Quality

In the European Community, rye is definedaccording to the support criteria as having aFalling Number of at least 120 s.

In Germany the expression bread rye is stillused and defined as having Amylogrammaximum temperatures of at least 63 C.Peak Amylogram viscosity is not used forevaluation, but the Falling Number is considered

additionally.The rheological index figures for rye as a rawmaterial are determined using a milled whole-meal product ground on a defined cross-beatermill, the Falling Number mill. For the rye floursnormally used in Germany, with a mineralcontent of about 1% (d.b.), the FallingNumbers for bread rye are about 120 to 130 sand the Amylogram gelatinization temperaturesare 64 to 65 C.

Increasing Falling Numbers and Amylogramvalues for rye have established themselves

15.4 Rye Quality

Tab. 69: Percentages of the main rye varietiesgrown in Germany (2004 harvest)

Pure breeds % Hybrid varieties %

Nikita 11 Avanti 23

Amilo, Recrut 3 Fernando 12

Danko, Hakada 1 Picasso 25

Esprit 35

Treviso 1

21 Bundessortenamt, German Federal Institute for varieties

189


3/14

Rye

Flo

ur

181

almost unnoticed, partly because of selectionby breeders and partly as a result of morefavourable weather and more accurate fore-casts of the ideal time for harvesting. But thefollowing are further reasons for the change inthe rheological values of bread rye:

increase in the total pentosan content; reduced proportion of soluble pentosans; reduced or delayed effect of the amylase

naturally contained in the grains, or of itsenzymes;

shift in the range of varieties towards more

high-yield hybrids; changes in cropping areas and thus thegrowing sites for rye;

specific use of agricultural inputs,especially to increase the yield;

great improvements in harvestingtechniques;

greatly improved post-harvest treatment; slight changes in the milling process and

flour yields; certain changes in the tolerances for

minerals in classified rye flour types.

Nevertheless, rye remains a sprout-endangeredcereal, and in contrast to wheat the site onwhich rye is grown has a greater influence onthe regional harvest result than the variety.(Brmmer, 1999a)A comparison of the years 1960 and 2004 (Tab.70) shows the typical changes in the variousindex figures over the past four decades.Interestingly, the bread volumes have fallen in

spite of the higher values of the indirectmethods. (Brmmer 1999b,c).

15.5 Rye Varieties

Since 1992 the BSA has issued descriptions ofthe properties of rye as well as wheat varietiesand updated them where necessary.

The quality attributes of the varieties aredescribed by comparison with one or morereference varieties. For some time Halo hasbeen the reference variety. The results of otherrye varieties are then shown as a percentageof this reference variety (= 100%) and dividedinto categories from 1 to 9. Category 1 means

unfavourable results for an attribute.

The BSA's descriptive list of varieties currentlycontains 28 varieties of winter rye and threevarieties of summer rye. The ratio of purebreeds to hybrid varieties has shiftedcontinuously in favour of the higher-yieldhybrids since the latter were first approved.The current list contains 12 pure breeds and 16hybrids (next page, Fig. 93).

The suitability of rye, and products groundfrom rye, for making baked goods raised withsour dough or baker's yeast depends to alarge extent on their composition. Limitedenzymolysis is an advantage in processing(Drews 1971a, b). In this respect, rye varietieswith a low protein content and high pentosanlevels are said to be advantageous, as arethose with low enzyme activity, particularly-amylase.

15.6 Testing Methods forDescribing the Quality of Rye

For a long time the -amylase activity of rye

was thought to be the only factor limitingsuitability for bread making. Sprouted grain isknown to result in bread with a very moistcrumb. Weipert (1998a, b) therefore sought toestablish a correlation between -amylase

and Falling Numbers and Amylogram values.Only in the case of very low or relatively highamylolytic activities good correlations ofFalling Numbers and Amylogram values havebeen detected.

15.5 Rye Varieties

Tab. 70: Average changes in the analyticalvalues for rye flours of the types 997/1150

Variable measured 1960 2004

Falling Number s 110 240

Amylogram, peak temperature C 62 73

Amylogram, peak viscosity AU 200 750

Maltose % 3.0 3.8

Dough yield g/100 g 165 175

Baked volume mL/100 g 330 280

182


4/14

182

Rye

Flo

ur

For a long time, systematic tests to ascertainthe fundamental technical characteristics ofrye centred on the Amylogram and FallingNumber as standard methods. Since 1994,consideration has also been given to the totalpentosan content, the percentage of solublepentosans, the flour yield (in a standardmilling test) and suitability for bread-making(in a standard baking test using sour dough ina flour of the type 997). In 2002 this procedurewas updated and now includes tests on grainsand flour for Falling Numbers, the Amylogram,the new Rye Viscosity Test after Brmmer

(2002) and the standard milling and bakingtest.

15.6.1 Milling Properties

The milling properties of rye varieties aredetermined in a standard milling test on aBhler laboratory mill. The flour yield is assessedin relation to the mineral content of the mostimportant rye flour types (mineral contentaround 1.0% d.b.). Because of the differentstructure of rye cells, mechanical damage to

the starch grains during milling is relativelylow compared to that of wheat. In the sensoryanalysis, i.e. when rubbed between the

fingers, rye flours are generally found to befiner and smoother than wheat flours. Largerproportions of fine grains lead one to expectmore rapid water absorption (swelling) andincreased sensitivity, for example to enzymaticactivity. These structural differences areinfluenced by the nature of the starch, theproportion of larger and smaller starch granules,the enveloping function of the hemicullulosesand other factors.

15.6.2 Baking Tests

The suitability of rye varieties for baking in

Germany is generally tested with the Germanflour types 997 and 1150. But standard bakingtests with wholemeal rye flour can be carriedout with "Falling Number meal". For breadmade of mixed wheat and rye flour, Neumannand Brmmer (2000) have suggested "basicbaking tests".

Besides the practical baking test with sourdough there is also a baking test with yeast,without any acidification, and a further test is

carried out with a standardized addition of lacticacid depending on the mineral content of therye flour to be baked.

15.6 Testing Methods for Describing the Quality of Rye

Yield categories3 4 5 6 7 8 9

3

4

5

6

7

8

9

Amilo

BorellusHalo

Motto

BornDanko

HacadaNikitaPlato

Walet

WarkoBorestoCanovus

LocarnoUso

Carotop

Amando

CilionMatadorRecrutDinoApartClou

Novus

Gambit

Marlo

Picasso

UrsusGametTreviso

Avanti

Pure breedsHybrid varieties

FernandoFarinoEsprit

GoliathCaroass

FallingNumberlevels

Fig. 93: List of German rye varieties, 2002

183


5/14

Rye

Flo

ur

183

The most important attributes in the bakingtest with sour dough are dough yield anddough properties, volume yield, pore structure,elasticity of the crumb, purity of taste, and theflavour potential resulting from the sourdough. The results of the tests are used tocalculate a Quality Number. For the mills,especially, this offers excellent possibilities ofdescribing the quality of their flours.

Dough Yield and Dough Properties

Dough yield22 is an important economic factor.At the same time it has a considerable influence

on the processing properties of the dough andthe quality of the rye bread. Indirect processes(sour dough) and direct acidification (withdough acidifiers) require different amounts ofingredient water. In the direct process theamount required is about 4 to 6 parts greater,depending on water-binding capacity and thenature and quantity of the dough acidifier. Thewater added must be sufficient to enable easy(usually mechanical) processing of the dough.At the same time there must not be too much

release of water during baking, as this might

weaken the crumb. A possible overdose ofwater is manifested in very soft, moist crumband often a horizontal separation of the crumbfrom the crust, whereas vertical cracks in thecrumb of loaves indicate that too little waterhas been added. They may be caused by doughthat is too firm, by inadequate gelatinizationof the starch or by excessive water loss duringbaking. To determine dough yield in the sourdough baking test, Brmmer (1988) haspublished a Farinograph method that can alsobe used to determine the amount of water tobe added in the standard yeast and lactic acid

baking tests. Nevertheless, a constant wateraddition of 73% is still generally used in thesetwo special standard baking tests, although itis less in keeping with the raw materials.

To some extent dough behaviour can bepredicted by the swelling curve (Drews, 1971a,b). The curve shows that the degree ofsoftening and thus the dough yield and doughproperties do not correlate with the FallingNumber, the Amylogram and volume yield

(Fig. 94 and Fig. 95).


22 Dough yield = sum of water and flour; i.e. a dough of 185 results from 100 kg of flour and 85 kg (litre) of water.

50100150200250300350400 55 60 65 70 75 80 85 90

165

170

175

180

185

FallingNumber (s) Amylogram max. temperature (C)

Dough yield

Fig. 94: Comparison between the values for indirect methods and dough yield in the baking test with rye flour andsour dough (German harvests of 1999 - 2002)


6/14

184

Rye

Flo

ur

Volume Yield

The volume development of rye bread is fairlylimited. The average value is about 300mL/100 g of rye flour with fluctuations of about 10% depending on quality. So with rye thedifferences in bread volume between varietiesare considerably smaller than with wheat,where they are about 150 mL/100 g in otherwords about 25% in wheat flours of the type550. Because of the slight differences, volumewas long considered fairly unimportant for thebaking value of rye. It does, however, have a

decisive effect on the properties of the crumband on shelf-life.

Elasticity of the Crumb

An important attribute for rating the quality ofrye bread is the elasticity of the crumb. A tech-nological objective is to produce a crumb thatis moist and pleasantly cohesive and bindingand at the same time elastic. In milled rye pro-ducts, poor crumb elasticity usually onlyoccurs in the case of rye whose constituentshave an increased tendency to break down("sprouting"). But poor crumb elasticity mayalso be a result of processing, e.g. excessivedough yields, too little acidification, very high

volume due to extra ingredients, inadequate

baking etc. Raw materials that do not breakdown readily (with high Falling Numbers orAmylogram values), over-firm dough proces-sing or conditions that aggravate both theseweaknesses (e.g. too little swelling of theconstituents of the rye during processing ofthe dough, too little pre-dough, i.e. sour)result in a firm crumb, reduced inflation andthus poorer keepability of the baked goods.Such disadvantages have often occurred inthe past ten years.

Quality Number

The calculation of a Quality Number takesaccount of efforts to achieve resistance tosprouting, which were dominant for a longtime, and also dough properties.

On the basis of baking tests with sour dough,the dough yield, the volume yield and inparticular crumb elasticity were included. Thisbasis for evaluation was then extended tocover further criteria, such as dough properties,and a new description and classification ofquality. The new characterization system wasalready used in the Walsrode Test.


260 280 300 320 340 360

165

160

170

175

180

185

Volume yield (mL/100 g flour )

Doughyield(kg/100kgflou

r)

240

Fig. 95: Comparison between volume yield and dough yield in sour dough baking tests with rye flour(German harvests of 1999 - 2002)


7/14

Rye

Flo

ur

185

15.7 Walsrode Test

In 2000 a test was carried out in cooperationwith Frderverein Pflanzenbau e.V. in Walsrode.Some of the trial fields of rye were threshed atthe usual presumably optimum harvestingtime, whereas the rest were threshed aboutfour weeks later. The quality parameterschanged as follows between the first andsecond harvesting dates (Tab. 71):

It was no surprise to the initiators of this test

that the rye and the flours (Type 997) producedby the standard milling method from thesecond harvest had superior baking properties.Because of their lower (but more suitable)rheological values, these products were in abetter range for baking. However, the highestQuality Number, 5.00, was not reached since

the volume achieved even with the samplesfrom the second harvesting date was stilllimited. Points were deducted because theresulting crumb lacked optimum moisture andsoft, elastic properties, and therefore optimumshelf-life.

15.8 Optimizing Bread RyeQuality for the Market

On the basis of the work of Drews (1971a, b) onthe introduction of a certain buffer for swellingcurves, the Rye Viscosity Test (RVT) was

developed. The test makes it possible toobtain some important additional informationin about 30 to 45 min, a time that can usuallybe spared when rye is taken in, for example bya mill. Because of the small sample quantitiesit requires, the RVT can also be carried out bybreeders as a selection criterion. The RVT iscurrently undergoing practical trials, and over100 samples have already shown a certaincorrelation with baked volume. At the sametime it has yielded further proof that some lots

with higher Falling Numbers may have goodinflation potential. In the past, only the Amandovariety was known to have this property. Whencompared with other varieties it always producedthe largest bread volume, independently ofthe site on which it was grown and its FallingNumbers and Amylogram values (Fig. 96).

15.8 Optimizing Bread Rye Quality for the Market

Tab. 71: Quality values for rye harvested atdifferent times under otherwise

identical growing conditionsDeterminant 1st harvesting 2nd harvesting

date date

Falling Number s 240 175

Amylogram, peak temp. C 70 66

Sour dough baking test,

Quality Number 4.60 4.90

280

290

300

310

320

330

340

350

360

1 2 3 4 5 6 7 8Site

Amando

280

290

300

310

320

330

340

350

360

1 2 3 4 5 6 7 8

Mean of all varieties except Amando

Volumeyield

(mL/100g)

Fig. 96: Volume yields (rye/sour dough baking tests) of flours from the rye variety Amando compared with flour from othervarieties (mineral content approx. 1% of dry weight; 1998 harvest)


8/14

186

Rye

Flo

ur

Because of the baking results obtained overthe past decades, the author considered it

necessary to modify the current practice ofassessing rye solely according to the criteriaof the BSA's descriptive list of varieties, withsteadily increasing results for 1000-grainweight, crude protein, Falling Numbers andAmylogram values. More and more, rye lotsare being recommended whose high rheologicalFalling Number and Amylogram values areoutside the optimum range for good rye breadquality. One way of achieving a more accurateprediction of bread quality is to carry out a

standard baking test and determine doughyield, the degree of leavening, the volume ofthe bread and the elasticity of the crumb asquality criteria.

15.9 Current Rye Research andProcessing Properties

Compared with other cereals, rye has only briefsecondary dormancy. So under unfavourableweather conditions germination may start

again, even in the blade, soon after themorphological ripening of the grains. Ifgermination is visible it is known as visiblesprouting. To the extent that they can bedetected analytically, the preliminary stages ofgermination are described as latent sprouting.

Such germination leads to increased enzymeactivity, which in turn results in the breakdownof components of the cell walls and alsostored substances. As sprout-damaged rye isconsidered unsuitable for bread-baking, thispresented a challenge to breeders. In the past,-amylase activity was generally measured as

a selection criterion; now the assessment isalmost always made on the basis of the FallingNumber.

In rye research and analysis the pentosancomplex used to be given greater attentionthan the structure of the starch. But the

following starch ratios are considered relativelyconstant. At the time of ripening, the cerealstarch consists of about 25% amylose and75% amylopectin. The starch grains can bedivided into two types: larger, lentil-shaped

bodies with a diameter of about 40 mm "A-types" and smaller, more spherical"B-types" with an average diameter of about10 mm. Besides these there is a fluctuating butnevertheless appreciable percentage ofmedium-sized starch grains. The exact ratio ofA to B types of starch grains in rye is notknown. Whereas about 90% of the starchgrains in wheat are of the B type, the percentageof these smaller grains is thought to besomewhat smaller in rye. This may havesignificance for resistance to sprouting, sincethe smaller B starch grains and also the

medium-sized types are more readily attackedby amylases because of their larger specificsurface area. But in spite of their larger number,the percentage of smaller starch grains in theoverall mass is fairly small in terms of volumeand weight. Dreisrner (2002) also found aconsiderable proportion of medium-sizedstarch grains that increases with breeding.

The starch is broken down by hydrolases,mainly through the combined activity of the

- and -amylases in the cereal grains. Whenthe grain is stored in the field, especially,-amylases from moulds and bacteria on the

ears and grains may have this effect. Inparticular the dextrins formed by -amylase

may then be exposed to further attack by-amylase or amyloglucosidase.

The-amylase newly formed during germination

seems to be an important factor influencingprocessing quality. Its concentration increasesduring ripening and reaches the highestvalues if latent or visible sprouting occurs.A further breakdown is possible duringgelatinization of the rye starch in the bakingprocess, in the presence of sufficientwater, high temperatures and a pH that is nottoo low.

There is an increase in temperature even whenthe grain is dried, but little moisture is

present. Such tempering has also been foundto reduce the tendency to gelatinize. Thismeans that the water content of the grains isextremely important for the activity of theenzymes. Their effect seems to be greatest at

15.9 Current Rye Research and Processing Properties

180


9/14

Rye

Flo

ur

187

a grain moisture of 30 - 40% and is largelyprevented at values below 20%.

Determination of-amylase is a complicated

matter. It is measured with a large excess ofwater and often with the addition of a foreignsubstrate, e.g. coloured starch. So determinationof enzyme activity is even farther removedfrom the conditions of bread-making than theFalling Number or Amylogram method.However, the effect of the enzymes duringprocessing is more important than the enzymeactivity that exists in absolute terms.

The grains contain a total of about 7 - 10%pentosans. Like proteins, they are one of theswelling substances of the rye, but unlike proteinthey are not considered to be energy reserves.The insoluble pentosans are a component ofthe cell walls. The ratio of the soluble pentosans(part of the content of the cell) to the insolublepentosans (constituents of the cell walls) hasyet to be determined. Larger percentages ofinsoluble pentosans are indicated by increasing

Falling Numbers of the flour, whereas largerpercentages of soluble pentosans seem toaffect the peak values of the Amylogram butnot the Falling Numbers. The pentosans are

15.9 Current Rye Research and Processing Properties

Fig. 97: Flow diagram of the Rye Viscosity Test

readily attacked even at dough temperatures,so it makes sense from the technical point ofview to determine them.

The behaviour of the swelling substances ofthe rye during processing (e.g. viscosity of thedough) is therefore determined by the pentosanand protein content and its susceptibility toattack.

Certainly an adequate reduction of viscosityhas to be ensured in order to achieve therequired attributes of the bread. This complex

will doubtless become an important feature oftechnical rye research in the near future,especially as some rye varieties seem to reactmore sensitively than others to an overdose ofwater or cause greater softening of the doughin spite of high Falling Numbers, as swellingcurves and the new Rye Viscosity Test(Brmmer, 2002) show (Fig. 97).Successful breeding in respect of yield and thereliability of the yield is making rye moreattractive again as a crop. Both of these factors

and also resistance to sprouting still dependchiefly on the weather, harvesting techniquesand post-harvest treatment and less on theproperties of a particular rye variety. In

300g

0

35

70

pH 4.5

40 C

+70 mL

Rye

weighing Dosing

Stir by hand

to remove

lumps

Transfer

100g free of

bubbles and

close

15 min dough

resting time

50,0

190,0

1 min

Weigh after

constant

outflow timeOpen after

15 min

e.g. 15; 30; 60 min

Result, g (net)

Falling

Number

mill

50 g

184


10/14

To answer this question, bakers have mainlyconsidered the Amylogram and the bakingtest, complemented by the Falling Number,maltose content and swelling curve. TheFalling Number is a quick determinationmethod, but it is subject to greater fluctuationsin respect of suitability for processing than thepeak Amylogram temperature, for example.

Fig. 99 is an attempt to correlate the results ofindirect methods with good bread quality. The"quality window" in the centre of the diagramshows the analytical ranges especially

recommended for making bread and othersmall products containing rye. Outside thisframe the uses of other ryes that break downmore readily or less easily during baking areshown. Ryes that break down very readilyshould only be used for coarse meal. Milledproducts that reach into the dry baking rangefor flours of the types 997/1150 may be regardedas particularly suitable for fine whole meal orwholemeal flour.Of course lots of this kind can also be used

for making special baked products such ascrispbread or to improve lots of rye whosesubstrate is too susceptible to attack orwhich show too much enzyme activity (mixedrye).

At present, millers are still very hesitant togrind rye with low Falling Numbers andAmylogram values in the usual way probablya result of bakers' fears. But some bulk buyershave now recognized the opportunities

offered by such rye properties for enhancingthe quality of their bread

15.10 Changes in Milled RyeProducts

15.10.1 Milling Technology

The tendency found in rye for the proportionsof the substances contained in the grains tochange in relation to each other naturally

affects the milling properties, although this isless evident with wholemeal products. Highercrude protein levels are often thought tocoincide with a lower flour yield.

188

Rye

Flo

ur

Germany, the characteristics of different ryevarieties were only apparent under veryuniform weather conditions.

But in spite of fluctuations, years of qualitytesting of milled rye products have revealedcertain trends (Fig. 98).

The past few years, including the harvest of2001, have almost made us forget that rye isstill susceptible to sprouting. Although the ryeof 1993 and 2002 broke down rather morereadily, the commercial flours were drier when

baked than ideal bread flours. This raises thequestion as to how much "sprouting" isnecessary for baking bread and other, smallerproducts containing rye.

15.10 Changes in Milled Rye Products

Fig. 98: Comparison of the analytical data for the Germanrye harvests of the years 1983 - 2002(rye flour types 997/1150)


11/14

Rye

Flo

ur

189

15.10 Changes in Milled Rye Products

Fig. 99: Processing quality and results of indirect methods for rye: rye Amylogram peak temperatures and Falling Numbers

and expected suitability of the milled products for baking

The slightly higher dough yields and theaddition of water-binding substances (e.g.hydrocolloids or wheat gluten) made it possible

to compensate for this up to a point, but theproperties of the crumb nevertheless shiftedin the direction of tough and rubbery ratherthan moist and soft.

A change in viscosity is also noticeable in thepre-doughs and sponge doughs. Whereasdough yields of 150 often used to be recom-mended for sour dough, rye pre-doughs withdough yields of 160 are now considered toofirm.

If sour doughs were still made according tothe earlier recommendations, most mixingmachines would be unable to achieve ahomogeneous mixture.The figure has therefore been raised to adough yield of about 180 or more. Nowadays,dough yields are chosen on the basis ofoperating procedures such as lifting of thedough out of the mixer by hand or pumpingof the sour. However, the water content hasrelatively little influence on the reactions in

the sour dough.The main factors are the temperature of thedough and the properties of the raw materials.Flavour development is also reduced, probably

Larger proportions of swelling substanceschange not only the ratio of swelling substancesto starch but also the separability of the

endosperm from the outer layers. This mayresult in milled products with a higher mineralcontent at the same degree of extraction.However, the overall mineral content haschanged little in recent years.

15.10.2 Baking Technology

From the point of view of baking technologythe following changes in rye as a raw materialhave occurred in recent years:

higher Falling Numbers of the flour; higher temperatures at the gelatinization

peak of the Amylogram; higher maltose values; increased dough yields; less uniform dough properties; less specific inflation, and thus reduced volume yields.

In the bread this led to changes in the elasticityand pressure resistance of the crumb from

well leavened and soft to less well leavenedand rather stiff.The crumb also lost some of its moisture andgood keeping properties.


12/14

constantly been raised. Because of this, lotswith balanced enzymatic effect were oftenrejected, or the mills had to treat the flour inorder to achieve the values stipulated in thecontract. It was found that treatment of theflour with enzymes can change the FallingNumber and Amylogram data, but it does notnecessarily have a positive effect on bakingproperties. Rye with "natural" FallingNumbers between 120 and 150 s usuallyproduces the best results, provided that thedough does not soften too much.

Even now, many bakeries still use multi-stagesour-dough processes, whatever the reasonmay be. Such processes used to be a reliableway of achieving good bread quality with highlyenzyme-active milled products that breakdown readily. In these and some other sourdough processes, work is carried out in singlesteps with large quantities of starter (30% ormore). The very acid conditions when a newsour dough starts to ferment reduce enzymaticconversion.

Milled rye products need sour dough to thisday, not necessarily to achieve an even, elasticcrumb but chiefly to form flavour componentsor their precursors, i.e. to enhance the taste ofthe bread. It is still not possible to separateacidification from flavour synthesis in the sourdough. Since the sour is so important as asource of flavour, the pre-doughs used shouldbe correspondingly reactive. In order not tooverdo acidification, it is advisable to work

with sour doughs made overnight with amoderate proportion of starter and with arelatively low starting temperature and a highdough yield.

We therefore recommend one-stage sour-doughprocessing with:

5 to 10% starter (based on the amount offlour or meal in the sour dough);

a dough yield of about 180 - 200%

(or higher if it is to be pumped); an initial temperature not exceeding 25 C

in the sour dough; fermentation times of 14 - 18 h.

because of changes in the properties of thesubstrate or reduced enzyme action, especiallyin the case of ryes with high Falling Numbers.

Changes similar to those in flours are alsofound in whole meal products. Even whenlarge proportions of wholemeal rye flour areused, too much water is often added to thedoughs in spite of their high water-bindingcapacity; this results in a very moist crumb orpoor crumb elasticity. This is also the case ifover-large amounts of water-binding additivesare used, such as hydrocolloids or wheat

gluten. Here too, more attention should begiven to the properties of the dough and theswelling or mixing curves of the raw materials.

The necessity for greater swelling of thepre-doughs is also apparent when rye meal isprocessed.

In the case of coarse meal, especially, thepercentages have had to be increased, forexample in the brew.

If the process is unsuitable, for example if thedough is kept warm too long, undesirablefermentation may take place as a result ofspontaneous reactions and greatly impair thetaste of the bread.

15.11 Possibilities of InfluencingMilled Rye Products

In the past, baking technology was directed

solely towards combating sprouting. We haveto take this into account when reading olderliterature and the recommendations suchworks give. In many cases out-of-date recom-mendations have been accepted withoutfurther thought for processing today's milledproducts.

In recent years, millers and bakers have gladlyaccepted improved raw materials and integratedthem into their quality systems with corres-pondingly adjusted data. For example, thestandard values for Falling Numbers and/or theAmylogram most often used for characterizingthe value of the product for processing have

15.11 Possibilities of Influencing Milled Rye Products

190

Rye

Flo

ur

187


13/14

Rye

Flo

ur

191

15.12 Summary

15.13 References

Anon., 1998. Der Roggenmehl-Verbrauch ist aufdem niedrigsten Stand der Nachkriegszeit.BackBusiness (7. September):15-16.

Autio K, Fabritius M and Kinnunen A, 1998. Effectof germination and water content on the microstruc-ture and rheological properties of two rye doughs.Cereal Chem. 75(1):10-14.

Belohlawek L, 1965. nderung der Substratspe-zifitt proteolytischer Enzymsysteme whrend derKeimung und Mlzung. Getreide Mehl 15(1):9-12.

Bttcher H, Weipert D, Hagedorn E and Garz J,

1997. Zur Verarbeitungsfhigkeit des Erntegutes ausdem Dauerversuch "Ewiger Roggenbau" inHalle/Saale. (The processing performance of ryegrain from the "Eternal Rye Cropping" experiment inHalle/Saale.) Khn Archiv 91(1):111-125.

Brmmer JM, 1984. Einfluss der Behandlung vonRoggenmehlen auf das Ergebnis von Backversuchenund indirekten Methoden. Getreide Mehl Brot38(6):166-173.

Brmmer JM, 1988. Erfahrungen mit derRoggenwasseraufnahme bei Roggentypenmehlen.Getreide Mehl Brot 42(9):272-276.

Brmmer JM, 1991. Auswirkungen von Sure undSalz auf Roggenmehlsuspensionen. Lehrinforma-tionen, Granum Verlag, Detmold Nr. 90, p 1-4.

Brmmer JM, 1995. Influences of rye flour treat-ment with pentosanases. International rye symposium:Technology and products. VTT Symposium 161, p155-159.

Brmmer JM, 1999a. Possibilities and Remediesof Reducing Sprouting Damage in Processing ofWheat and Rye to Bread. Proc. InternationalSymposium on Pre-Harvest Sprouting in Cereals 8,

1998, p 36-42. Brmmer JM, 1999b. Technologische Qualitts-aspekte der Brotgetreidearten in naher Zukunft.Getreide Mehl Brot 53(5):276-281.

Brmmer JM, 1999c. Vernderungen bei denVerarbeitungseigenschaften von Roggen undRoggenmahlerzeugnissen. Getreide Mehl Brot53(3):154-162.

Brmmer JM, 2002. Rye Viscosity Test. A newquick and simple rheological method for thecharacterization of bread rye and milled products forthe bread production in Germany. 2nd International

Conference "Grain, Flour and Bread Quality"Moscow, Russia, May 20-24.

Brmmer JM, 2002. Neue rheologische Methodenfr die Mllerei. Getreide Mehl Brot 56(2):74-80.

Although this sour dough should be used withinone day of being prepared, it can be kept for upto 48 h without refrigeration if its temperaturedoes not exceed 28 C. If this presents a problemin the hot summer months, it is advisable tostart at a somewhat lower temperature or touse the sour dough within 8 to 12 h of itsmaturing or to refrigerate it after this time.Bread doughs should be processed as soft asthe dough properties allow, and the temperatureshould be round about 28 C. The quantity ofyeast should be no more than 0.5 to 1.0% inrye bread and about 1.5 to 2.0% in mixed

wheat and rye bread to achieve good leaveningwithout too rapid fermentation. The amountof yeast needed naturally depends on theresistance of the yeast to acid, which meansthat the above figures are only a guide.

When rye flours that break down readily arebaked, it is not necessary to make changes tothe dough processing steps (including shaping)and fermentation. If only a small amount ofyeast is added the dough resting time is slightly

longer, but the final fermentation time canusually stay as it is. To achieve a soft, moistcrumb it has proved an advantage to choose ahotter and slighter shorter baking regime or tomake hearth bread or pan loaves. Acidificationmeasures, dough yield and the baking regimeremain the most important criteria for achievinga properly elastic crumb that is not too moistand does not roll into a ball i.e. pleasant-tasting, moist bread with a good shelf-life.

15.12 Summary

The aim of this contribution is to show howimportant the properties of milled productsare even during preparation of the dough. Itincludes references to characterization of therye, not only on the basis of its behaviourduring the hot phase of baking but also in thecold phase, i.e. during the dough processes.The Rye Viscosity Test may be recommendedas a simple method of describing the dough

properties of rye for baking purposes morereliably, with emphasis on bread and othersmall baked products leavened with yeastand/or sour dough.


14/14

Perten H, 1967. Factors influencing FallingNumber values. Cereal Sci. Today 12(12):516-519.

Popper L, 2001. Auswirkungen der Mehlbehand-lung auf die Frischhaltung der Brotkrume. GetreideMehl Brot 55(5):286-290.

Rakowska M, 1996. The nutritive quality of rye.Proc. International Symposium on Rye Breeding &Genetics, p 85-95.

Rattunde HFW, Geiger H and Weipert D, 1994.Variation and Covariation of milling and bakingquality characteristics among winter rye single-crosshybrids. Plant Breeding 113:287-293.

Rohrlich M and Hitze W, 1970. Aktivitt undVerteilung der Cellulase im reifenden Weizen und

Roggen sowie der alpha-Amylase im Keimling undEndosperm. Getreide Mehl 20(3):17-23.

Vorwerk K, 1976. Der Einfluss unterschiedlicherStrkebeschdigung bei der Roggenvermahlung aufdie Analysen und Backergebnisse. Getreide MehlBrot 30(1):1-5.

Vorwerk K, 1980. Probleme der Diagrammfhrungbei der Roggenvermahlung im Hinblick auf dieInhaltsstoffzusammensetzung der Mahlprodukte.Mhle+Mischfuttertechnik 117(11):131-134.

Weipert D and Brmmer JM, 1988. Untersuchung

von Roggen und Roggenmahlerzeugnissen. In:Angewandte Getreideforschung, Roggen-AnbauVerarbeitung Markt. Seibel W and Steller W (eds.).Behrs Verlag, Hamburg, p 85-120.

Weipert D, and Zwingelberg H, 1980. Quellstoff-/Strke-Verhltnis bei unterschiedlichen Roggen-qualitten. Getreide Mehl Brot 34(4):97-100.

Weipert D and Brmmer JM, 1998. Whole rye andwheat bread technical and health aspects. Proc.International Conference, Brno (Czech Republic),p 70-74.

Weipert D, 1998a. Auswuchs im Getreide seine

Bekmpfung und die Erfolge. Die Mhle Misch-futtertechnik 135(23):769-773.

Weipert D, 1998b. Roggen: Sorte und Umwelt. 1.Teil: Indirekte Qualittsmerkmale. Getreide MehlBrot 52(4):208-217.

Werner S, Habermeyer J and Zinkernagel V, 1998.Beeinflussung der Backwarenqualitt von Winter-roggen durch Fungizide. 33. VortragstagungDeutsche Gesellschaft fr Qualittsforschung, p 87-96.

Zwingelberg H, 1993. Herstellung und Qualittvon Mehlen nach der neuen Typenordnung. Getreide

Mehl Brot 47(1):19-25.

192

Rye

Flo

ur

Bundessortenamt, 2001. Beschreibende Sorten-liste 2001. Getreide, Mais, lfrchte, Leguminosen(grokrnig), Hackfrchte (auer Kartoffeln).

Landbuch Verlag, Hannover. Bushuk W (ed.), 1976. Rye: Production, chemistry,and technology. AACC, St. Paul, Minnesota, USA.

Dreisrner J, Eichner K and Lindhauer MG, 2002.Physicochemische Einflussfaktoren auf dieFrischhaltung von Roggenbroten. Jahresbericht2001 der Bundesanstalt fr Getreide-, Kartoffel-und Fettforschung in Detmold und Mnster, BAGKF,Detmold.

Drews E and Zwingelberg H, 1977. Ergebnisselangjhriger Roggenuntersuchungen ber Sorte,

Standort und Erntejahr hinsichtlich des Mahlverhal-tens. Deutsche Mllerzeitung 75(10): 189-192.

Drews E, 1970. Beschaffenheitsmerkmale derPentosane des Roggenmehles. Brot Gebck24(3):41-46.

Drews E, 1976. Der diastatische Zustand desRoggens. Getreide Mehl Brot 30(9):240-244.

Drews E, 1979. Der Einfluss der Quellstoffe auf dieVerarbeitungseigenschaften des Brotgetreides undden Verarbeitungswert der Getreideprodukte. Teil I I:Roggen. Mhle Mischfuttertechnik 116(40):544-549.

Drews E, 1971a. Quellkurven von Roggenmahlpro-dukten. Mhle Mischfuttertechnik 108(49):723-724.

Drews E, 1971b. Die Roggenbackfhigkeit inneuer Sicht. Brot Gebck 25(1):1-6.

Kujala T, 1999. Rye: Nutrition, health and functio-nality. Nordic Rye Research Group, Helsinki.

Mettler E, Seibel W and Brmmer JM. 1992.Maturograph und Ofentriebgert zur Beurteilungdes rheologischen Verhaltens von Roggenteigen.Getreide Mehl Brot 46(10):300-307.

Meuser F, and Suckow P, 1986. BacktechnischeWirkung von Roggenpentosanen. Getreide MehlBrot 40(11):332-336.

Miedaner T, 1997. Roggen Vom Unkraut zurVolksnahrung. DLG-Verlag, 60489 Frankfurt.

Neumann H and Brmmer JM, 2000. Definitioneiner neuen Qualittszahl fr die backtechnischeBeurteilung von Roggen-Handelsmehlen der Typen997/1150Getreide Mehl Brot 54(1):11-14.

Ohnmacht B, 1990. Einflu von Witterung,Reifestadium und Cytoplasma auf die -Amylase-Aktivitt im Roggenkorn. Dissertation, Fakultt III,Agrarwissenschaften I der Universitt Hohenheim,

Stuttgart. Parkkonen T, Hrknen H and Autio K, 1994.Effect of baking on the microstructure of rye cellwalls and protein. Cereal Chem. 71(1):58-63.

15.13 References

Documents

Faina de secara