The contents of dietary fibre and available carbohydrates in Finnish cereal products were analysed using the Englyst total carbohydrate method. The tabulation gives the carbohydrate compositions of 44 cereal foods. The cereal-based estimated daily intakes were: total soluble sugars 14.8 g, starch 103 g and dietary fibre 11.6g (energy level 10 MJ)

Kirsti Veijalainen

Kristiina Pero

Pekka Koivistoinen

Pertti Varo

Raili Laine

Agricultural and Food Science

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Maataloustieteellinen AikakauskirjaVol. 56: 39—48, 1984Dietary fibre and available carbohydrates in Finnish cereal productsPERTTI VARO, RAILI LAINE, KIRSTI VEIJALAINEN, KRISTIINA PERO andPEKKA KOIVISTOINENDepartment of Food Chemistry and Technology, University of Helsinki,SF-00710 HELSINKI, FinlandAbstract. The contents of dietary fibre and available carbohydrates in Finnish cerealproducts were analysed using the Englyst total carbohydrate method. The tabulation gives thecarbohydrate compositions of 44 cereal foods. The cereal-based estimated daily intakes were:total soluble sugars 14.8 g, starch 103 g and dietary fibre 11.6 g (energy level 10 MJ).IntroductionCereal products are the major source ofmost carbohydrates. They are the most im-portant source of starch, and usually of di-etary fibre. Certain bakery products containconsiderable amounts of sugars, added assucrose or syrups or as lactose from pow-dered milk.The functions of carbohydrates in foodsand nutrition are various. Although chem-ically related, the carbohydrates are difficultto analyse simultaneously. Southgate(1969), Southgate et al. (1978), Englyst(1981), and Theander & Äman (1982) havedeveloped methods that allow available car-bohydrates and dietary fibre to be deter-mined within a single analytical procedure.The method chosen in this study was theanalytical scheme of Englyst (1981).The present study is part of a research pro-ject determining the carbohydrate composi-tion of Finnish foods. The project, in turn,is part of a larger attempt to gather new anddependable data on Finnish foods and diet,of which the studies on mineral compositionhave been completed (Koivistoinen 1980,Varo 1981). The need for such data has be-come increasingly evident along with the sop-histication of our daily lives: the informationis required by nutritionists, dietitians andfood inspectors, in the industry, and formedical research, to mention but a few.Material and methodsThe samples used in this study were col-lected for a previous study on the mineralelement composition of Finnish foods (Koi-Index words: food composition, dietary intake, sugars, starch, dietary fibre39JOURNAL OF AGRICULTURAL SCIENCE IN FINLANDvisioinen 1980). The original study com-prised an average of 4—6 samples per fooditem, representing large amounts of theproduct. In the present study, only onesample, pooled from two samples chosen atrandom, was analysed per item. This is a re-flection of the complexity of the analyticalprocedure, which allowed only a very limitednumber of samples to be analysed within thecontext of the present study. For the prin-ciples of sampling and the details of sampl-ing procedures, refer to the reports of themineral study (Koivistoinen 1980).The analytical scheme used was that de-veloped by Englyst (1981) and slightly mo-dified by Laine et ai. (1981). The methodmeasures the total carbohydrate compositionas the following fractions: soluble sugars,starch, and dietary fibre as cellulose, water-soluble and water-insoluble non-cellulosicpolysaccharides (w.s. and w.i.s. NCP, re-spectively), and lignin. The detailed sugarcompositions of soluble sugars, w.s. NCPand w.i.s. NCP are determined by gas chro-matography (GLC).The dry sample (200 mg) is incubated in anacetate buffer (pH 6, 48°C), first on its ownfor 5 h (aliquot 1)and then with amylogluco-sidase (16 h), after which it is separated bycentrifugation into aliquot 2 and residue.The supernatants are analysed for free su-gars, starch and w.s. NCP. Free sugars (ali-quot 1), and free sugars and glucose fromstarch together (aliquot 2) are freeze-dried,formed into aldonitrilo acetates (Morrison1975) and analysed by GLC. W.s. NCP areprecipitated with 4 volumes of ethanol fromaliquot 2, hydrolysed with 1 M H2S0 4 andanalysed for neutral sugars as aldonitriloacetates by GLC and for uronic acids colori-metrically after the carbazole reaction (Bit-ter & Muir 1962). The residue is sequen-tially hydrolysed with 1 M H2SG 4 and 72 %H2S0 4, and analysed by GLC and colori-metry for w.i.s. NCP constituents, by colori-metry for cellulose (Roe 1955), and gravi-metrically for lignin.The chromatography of the sugars wasperformed using an equimolar mixture ofdifferent sugars as an external standard, andinositol as an internal standard.The overall analytical feasibility of themethod was tested in two interlaboratorycomparisons made during the present study(Theander 1981, Varo et ai. 1983). Wholemeal wheat flour, which was used as a stand-ard, was analysed several times during thestudy. As seen in Table 1, the variation insome fractions may be considerable. Thismay be due at least partly to the initial smallsample size (200 mg). All samples were anal-ysed as six replicates, and the fractions withover 10 % variation were re-analysed. Theanalysis of starch tended to be especiallyproblematic, and so it was also analysed ona macroscale from all samples using enzy-matic hydrolysis and colorimetry. Free su-gars and, less often, lignin also entailed re-checks.Table 1. Carbohydrate composition of wheat flour (standard), g/100 g dry matter.Sample no.1 2 3 4 5 X 1 s V%Free sugars 3.1 2.4 3.1 2.5 3.2 2.9 0.4 14Starch 58.3 61.8 62.4 61.9 63.2 61.5 1.9 3Dietary fibre 13.3 11.3 11.9 12.8 12.5 12.4 0.8 7w.s. NCP 1.7 1.2 1.2 1.8 1.4 1.5 0.3 20w.i.s. NCP 8.0 7.0 7.5 7.7 8.1 7.7 0.4 5cellulose 2.3 1.9 2.0 2.2 2.0 2.1 0.2 10lignin 1.4 1.3 1.2 1.1 1.0 1.2 0.2 171 X = mean, s = standard deviation, V% = coefficient of variation.40Table2.CarbohydratecompositionofFinnishcereal-basedfoods.Contentin1.011.021.031.041.051.061.071.081.091.10100goffoodWheatWheatWheatWheatWheatWheatRyeRyeBarleyRolled(edibleportion)flour,flour,flour,flour,brangermflour,flour,flour,oatswhole-c.1.3%c.0.7%c.0.5%whole-c.0.5%whole-mealashashashmealashmealWaterg14141414141314141412Availablecarbo-g54.559.463.563.615.431.052.066.358.957.0hydrates Freesugarsg0.70.50.50.41.316.42.40.50.91.3fructoseg0.10.10.20.20.20.60.30.10.20.2glucoseg0.10.10.10.10.20.60.20.20.20.2sucroseg0.50.30.20.10.915.21.00.20.50.9maltoseg0.9tr—-lactosegStarchg53.858.963.063.214.114.649.665.858.055.7Dietaryfibreg9.95.53.63.537.514.013.64.57.65.7W.s.NCPg1.01.01.00.91.21.32.21.51.01.1W.i.s.NCPg6.53.21.71.724.28.96.91.94.03.1Celluloseg1.50.60.50.47.52.31.90.91.30.7Ligning0.90.70.40.54.61.52.60.21.30.841Contentin1.111.121.131.141.151.161.171.181.191.20100goffoodRice,Rice,RyeWheatWheatOatBrownCrispCrispWhole-(edibleportion)polishedpar-bread,breadbread,breadbread,breadbread,wheatboiledsourdarksweetenedwholeryeruskWaterg14123833363635854Availablecarbo-g75.570.936.941.340.041.240.056.157.863.9hydrates Freesugarsg0.30.73.53.22.63.57.81.62.42.1fructosegtrtr0.80.30.20.82.80.31.20.3glucosegtr0.10.80.20.20.52.40.21.00.3sucroseg0.30.6tr0.1tr0.1trtr—-maltoseg1.92.52.12.22.51.10.21.5lactoseg0.2Starchg75.270.233.438.137.437.732.255.555.461.8Dietaryfibreg2.34.89.93.55.06.44.712.914.98.5W.s.NCPg0.20.61.70.81.01.21.12.92.71.4W.i.s.NCPg1.63.16.11.72.73.92.56.68.04.9Celluloseg0.20.70.90.60.70.80.81.92.21.3Ligning0.30.41.20.40.60.60.31.52.00.94243Contentin1.211.221.231.241.251.261.271.281.291.30100goffoodSweetSweetDoughnutSwissBiscuitCream»Mämmi»MacaroniCornRice,(edibleportion)wheatwheatrollcrackerEasterflakespuffedbread,bread,dessert5%fat10%fatWaterg2016222525591243Availablecarbo-g49.743.244.440.969.957.427.666.480.278.6hydrates Freesugarsg10.58.613.325.319.61.613.20.56.15.2fructoseg3.83.01.61.02.40.36.40.10.90.4glucoseg3.02.21.91.92.10.34.50.21.50.4sucroseg0.70.48.322.114.42.20.23.64.4maltoseg2.32.21.5tr0.71.0lactoseg0.70.80.3Starchg39.235.631.115.650.355.814.465.974.173.6Dietaryfibreg3.62.82.51.52.04.34.93.15.45.0W.s.NCPg0.80.90.70.80.41.31.21.00.40.5W.i.s.NCPg2.11.51.20.40.82.31.91.63.13.4Celluloseg0.50.30.30.10.40.40.70.30.70.3Ligning0.20.10.30.20.40.31.10.11.20.8Contentin1.311.321.331.341.351.361.371.381.391.40100goffoodOats,RoastedBuckwheatMillet,SpringRye,Barley,Oats,RiceMaize,(edibleportion)puffedoatmeal,wholewholewheat,wholewholewholewholewhole»Talk-graingrainwholegraingraingraingraingrainkuna»grainWaterg3141414141414141313Availablecarbo-g70.657.660.455.352.952.948.247.365.463.6hydrates Freesugarsg9.80.70.40.62.62.41.30.30.81.0fructoseg0.3trtr0.20.20.40.20.1tr0.1glucoseg0.30.10.20.30.30.60.30.20.30.5sucroseg9.20.60.20.10.81.00.6tr0.50.4maltoseg1.30.40.2lactosegStarchg60.856.960.054.750.350.546.947.064.662.6Dietaryfibreg4.99.95.83.210.812.716.518.57.49.2W.s.NCPg0.71.60.80.61.32.42.21.81.10.8W.i.s.NCPg3.43.62.81.66.66.88.07.13.65.9Celluloseg0.42.41.50.41.82.23.76.21.72.0Ligning0.42.30.70.61.11.32.63.41.00.544Results and discussionThe available carbohydrates and fibreconstituents of Finnish cereal products aregiven in Table 2. The results are largely con-sistent with those reported previously for ce-real foods (Paul & Southgate 1978, Souciet al. 1981, Salo & Kotilainen 1970, Fro-lich & Asp 1981).Free sugars. Cereal grains and flours arelow in sugars, sucrose being the main one.Maltose was usually found only in traceamounts. Sugars other than those tabulatedwere sometimes detected (e.g. 4 % raffinosein wheat germ). Bakery products with addedsucrose and leavened with yeast containedonly little sucrose, but more fructose andglucose. Breads commonly contained 12 °?o maltose. Lactose was detected in breadswith added milk or powdered milk.Starch. The starch content of cereal prod-ucts was generally in the expected range. Thestarch content was highest in polished riceand lowest in nuts.Dietary fibre (DF). The fibre content ofcereal products follows closely the extractionof flour used as a raw material. The bulk ofthe fibre constituents are in the bran frac-tion. Whole meal wheat flour containedabout10 % DF, whereas white flour contained3.5 % and wheat bran c. 40 °Io. The fibreconcentration of many bakery products wasslightly higher than might be expected oftheir raw materials. This may indicate thatbread making causes an increase in theamount of fibre especially while the crust isforming. However, not only lignin but otherfibre fractions, too, were slightly increased.Similar increments have been found in heat-treated potato (Varo et al. 1983, Varo et al.1984).W.i.s. NCP was generally the main DFfraction in cereal products. The presentmethod shows that the concentrations of eel-Contentin1.411.421.431.44100goffoodDis-Pea,Hazel-Almond(edibleportion)tiller'sdriednutspentgrainWaterg121555Availablecarbo-g1.148.53.46.6hydrates Freesugarsg0.02.13.46.6fructoseg0.10.50.5glucoseg0.20.40.3sucroseg1.82.55.8maltoseglactosegStarchg1.146.40.00.0Dietaryfibreg21.010.76.07.2W.s.NCPg4.70.70.30.3W.i.s.NCPg8.44.12.53.7Celluloseg3.15.71.41.5Ligning4.80.21.81.74546lulose and lignin were approximately thesame in cereal foods. The concentration ofw.s. NCP was fairly constant. As an exam-ple, whole meal wheat flour and white wheatflour contained equal amounts of this frac-tion.Table 3 gives the relative neutral sugar anduronic acid compositions of w.s. NCP andw.i.s. NCP of some flour and bread samples.The most variable is that of glucose, especial-ly in the w.i.s. NCP fraction, suggesting thattraces of starch may have been left in someof the w.i.s. NCP fractions. The relativeamounts of other constituents remain fairlyconstant with increasing extraction.Since the number of samples was limitedto one per item, no information was obtain-ed in the variation within a single food com-modity. The main purpose of the study, toobtain average carbohydrate values for asmany of the principal cereal foods as possi-ble, was probably covered reasonably wellconsidering the sampling procedure, whichwas planned to produce samples representinghigh volumes of production.The analytical procedure chosen for thepresent study is too laborious for routinefibre determinations. The actual rate wasonly 2—4 samples/week/2 technicians. Theneed for rechecks of results was also unde-sirably high despite careful standardizationof the procedures. One major problem wasthe difficulty of obtaining exactly repro-ducible fractionation of the small quantity ofstarting material. For instance, the gravimet-ric determination of a few milligrams of lig-nin necessarily caused high variation, whichwas greatly enhanced by small differences infractionation.In 1981 the consumption of cereals in Fin-land was 209 g/d/person, of which 128 g waswheat, 57 g rye and the rest equal amounts ofbarley, oats and rice (Agric. Econ. Res. Inst.1983). Nearly all the rye is consumed aswhole grain products, whereas about 80 °/oof the wheat is used as refined flour (Salo-vaara 1979). About 70 % of all industrialbakery products are unsweetened rye and Table3.Sugaranduremicacidcompositionofw.s.NCPandw.i.s.NCPinsomecerealproducts.w.s.NCPw.i.s.NCP%oftotal/lAr,%oftotal/ln_g/100gg/100grhamanglugalaraxylurototal8rhamanglugalaraxylurototal"Wholemealwheatflourtr71114254041.211103255367.6Wheatflour,1.3°/oash4720211632tr1.2tr2133294393.7Wheatflour,0.7%ashtr412152544tr1.202414172852.0Wheatbrantr4178244251.401922953628.1Wheatbread,whitetrtr1010245321.205504152612.5Wholeryeflour05104284942.602214244278.0Ryecrispbread2374295052.804196254348.4Rolledoats544681212131.323199253573.5"Indryproduct Abbreviations:rha=rhamnose,man=mannose,glu=glucose,gal=galactose,ara=arabinose,xyl=xylose,uro=uronicacids,tr=tracesw.s.=watersoluble,w.i.s.=waterinsoluble,NCP=non-cellulosicpolysaccharideswheat bread, the remainder being sweetenedproducts. Home baking, however, increasesthe share of sweetened products to at least40 % of total bread consumption. It is es-timated that homebaked products accountfor about 13 % of total sugar consumption(Prättälä 1983). These findings, togetherwith data on the detailed distribution of theproduction of bakery products (Salovaara1979), and the present analytical data en-abled us to estimate roughly the average in-take of carbohydrates from cereal products(Table 4).Acknowledgement. This study has been supportedbythe Academy of Finland and the Finnish Sugar Com-pany Ltd.Table 4. Cereal products as sources of sugars, starchand dietary fibre in 1981 (energy level 10 MJ).g/dSugars 14.8sucrose 5.5glucose 2.5fructose 2.9maltose 3.5lactose 0.4Starch 103Dietary fibre 11.6w.s. NCP 2.3w.i.s. NCP 5.8cellulose 1,7lignin 1.8ReferencesAgricultural Economics Research Institute, 1983. Foodbalance sheet 1981. Helsinki.Bitter, T. & Muir, M.H. 1962. A modified uronic acidcarbazole reaction. Anal. Biochem. 4: 330—334.Englyst, H. 1981. Determination of carbohydrate andits composition in plant materials. In: The Analysis ofDietary Fiber in Food (Eds. W.P.T. James & O. The-ander), p. 71 —93. Marcel Dekker, N.Y.Frolich. W. & Asp, N.-G. 1981. Dietary fiber contentin cereals in Norway. Cereal Chem. 58: 524—527.Koivistoinen, P. (ed.) 1980. Mineral element composi-tion of Finnish foods. Acta Agric. Scand. Suppl. 22,pp. 171.Laine, R., Varo, P. & Koivistoinen, P. 1981. Observa-tions on the analysis of dietary fiber. In: The Analysisof Dietary Fiber in Food (Eds. W.P.T. James & O.Theander), p. 21—27. Marcel Dekker, N.Y.Morrison, I.M. 1975. Determination of the degree ofpolymerisation of oligo- and polysaccharides bygas-liquid chromatography. J. Chromatogr. 108:361—364.Paul, A.A. & Southgate, D.A.T. 1979. McCance andWiddowson’s The Composition of Foods, 4th ed.HMSO, London.Prättälä, R. 1983. Suomalaiset sokerinsyöjinä. Lisen-siaattitutkimus, Helsingin yliopisto, ravitsemustieteenlaitos.Roe, J.H. 1955. The determination of sugar in bloodand spinal fluid with anthrone reagent. J. Biol.Chem. 212: 335—343.Salo, M.-L. & Kotilainen, K. 1970. On the carbo-hydrate composition and nutritive value of some ce-reals. J. Scient. Agric. Soc. Finl. 42: 21—29.Salovaara, H. 1979. Viljan tiet kulutukseen. Leipätoi-mikunta, Helsinki.Souci, S. W., Fachmann, W. & Kraut, H. 1981. FoodComposition and Nutrition Tables 1981/82. Wis-senschaftliche Verlagsgesellschaft, Stuttgart.Southgate, D.A.T. 1969. Determination of carbohyd-rates in foods. 11. Unavailable carbohydrates. J. Sci.Food. Agric. 20: 331—335.Southgate, D.A.T., Hudson, G.J. & Enolyst, H. 1978.The analysis of dietary fibre the choices for theanalyst. J. Sci. Food Agric. 29; 979—988.Theander, O. 1981. Review of the different analyticalmethods and remaining problems. In; The Analysis ofDietary Fiber in Food (Eds. W.P.T. James & O. The-ander), p. 263—276, Marcel Dekker, N.Y.Theander, O. & Äman, P, 1982. Studies on dietaryfibre. A method for the analysis and chemical charac-terisation of total dietary fibre. J. Sci. Food Agric.33: 340—344.Varo, P. 1981. Kivennäisainetaulukko, 2. p. Otava,Helsinki.Varo, P., Laine, R. & Koivistoinen, P. 1983. Effect ofheat treatment on dietary fiber: Interlaboratorystudy. J. AOAC 66: 933—938.Varo, P. Veijalainen, K. & Koivistoinen, P. 1984. Theeffect of heat treatment on the dietary fibre contentsof potato and tomato. J. Food Tech, (in press).Ms received January 30, 198447SELOSTUSSuomalaisten elintarvikkeiden hiilihydraatti-tutkimus viljavalmisteiden ravintokuitu-,tärkkelys- ja sokeripitoisuudetPertti Varo, Raili Laine, Kirsti Veijalainen,Kristiina Pero ja Pekka KoivistoinenElintarvikekemian ja -teknologian laitos,Helsingin yliopisto, 00710 HelsinkiSuomalaisten viljavalmisteiden hiilihydraattikoostu-mus määritettiin tässä tutkimuksessa ns. Englystin ko-konaishiilihydraattimenetelmällä. Se antaa yksityiskoh-taisen kuvan sekä hyväksikäytettävien hiilihydraattienettä ravintokuidun määrästä ja laadusta. Tutkimus onosa poikkileikkaustutkimusta, jonka kohteena oli tär-keimpien suomalaisten elintarvikkeiden hiilihydraatti-koostumus. Menetelmän työläydestä johtui, että vainyksi kokoomanäyte kutakin nimikettä voitiin analysoi-da. Tutkimuksen vaikeutena olivat monimutkainenfraktiointikaavio ja pieni näytemäärä (200 mg), ja tar-kistusanalyysien määrä kasvoikin ajoittain epätoivotta-van suureksi.Saatujen tulosten jakulutustietojen perusteella arvioi-tiin hiilihydraattien keskimääräinen päiväsaanti viljaval-misteista. Liukoisia sokereita arvioitiin saatavan yhteen-sä 14.8 g/d, tärkkelystä 103 g/d ja ravintokuitua 11.6g/d (energiataso 10 MJ).48

Dietary fibre and available carbohydrates in Finnish cereal products

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Dietary fibre and available carbohydrates in Finnish cereal products

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