Measurement of Satiety of Wheat-Based Bulgur by Intervention and Sensory Evaluation

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1 RESEARCH Mesurement of Stiety of Whet-Bsed Bulgur y Intervention nd Sensory Evlution V. A. Solh, 1, 2 H. Fenton, 1 D. Kerr, 1 G. B. Crosie, 3 nd S. Siryni 4 ABSTRACT Twenty-two helthy sujects consumed the following four test mels: Austrlin ulgur processed y oiling (oiled ulgur), Austrlin ulgur processed y steming (stemed ulgur), Turkish ulgur, nd high-mylose rice. Austrlin ulgur ws mde from durum whet y using trditionl oiling nd drying method nd method in which steming replced oiling. Mels were presented in rndomized order, one mel per test session t the sme time nd dy of ech week over four consecutive weeks. A within suject crossover design ws used to investigte the stiety of ulgur in which ech suject cted s their own control. Visul nlogue scles were used to mesure ech suject s feelings of hunger nd clculte rnkings. Men stiety index scores nd re under the How hungry do you feel right now? curve vlues showed tht the ulgur smples provided greter stiety thn the high-mylose rice. Testing for differences in rnk sums showed tht ulgur (oiled nd stemed) rnked significntly lower (P < 0.05) for hunger t 1 nd 1.5 hr when compred with high-mylose rice. At 2.5 hr, ulgur (oiled) ws rnked s significntly different to high-mylose rice (P < 0.05). Austrlin ulgur processed y oiling or steming ws more stiting thn high-mylose rice. Bulgur is whole-grin food processed from whet, preferly durum whet, nd is defined y Byrm (2) s clened, cooked, dried, nd pulverized hrd whet. Bulgur is significnt product in the Middle Est nd Turkey with more thn 100,000 tons produced nnully. It is well known for its stiety, ut there is little or no scientific evidence to support this clim. The helth enefits ssocited with whole-grin cerel consumption, such s the prevention of cncer, hert disese, nd dietes, re lso likely to e oserved following the consumption of ulgur. The mesurement of stiety will provide results tht will help define ulgur s functionl food. Stiety refers to the stte in which further eting is inhiited nd occurs s 1 Curtin University of Technology, Perth, W.A., 6845, Austrli. 2 Corresponding Author. E-mil: v.solh@curtin.edu. u 3 Deprtment of Agriculture, W.A., South Perth, W.A. 6151, Austrli. 4 Smir s Nturl Foods, Riverwood, Sydney, N.S.W. 2210, Austrli. DOI: / CFW AACC Interntionl, Inc. consequence of hving eten (8). Fctors known to ffect stiety include energy density, weight nd volume, mcronutrient composition, prticle size, nd pltility. Weight cn ffect stiety through differences in ingestion nd digestion rtes, gstric filling nd emptying processes, nd the suject s perception out size nd ssocited feelings of fullness (17,23,24,28). Sensory properties cn ffect the suject s food choice nd intke (5,12,21,29,33,34). Pltility cn ffect stiety, for exmple, it hs een oserved tht highly pltle foods cn stimulte greter desire to et nd thus ffect susequent rtings of hunger (10,14). Whole-grin foods provide high stiety (18,19,22,25,27,35), ut studies into the level of stiety chieved from specific whole-grin foods re limited. The consumption of food tht provides high stiety leds to feelings of fullness tht is prolonged nd my increse the time etween eting occsions nd reduce susequent food intke (8,16). Therefore, diet contining foods with high stiety such s ulgur, my llow individuls to control their energy intke without hving to restrict their eting or endure high levels of hunger etween mels. A visul nlogue scle (VAS) ws used s vlidted method for trnslting sujective senstions into quntifile ojective mesure to ssess stiety (4,6,11). A VAS provides tool for ssessing the feeling of hunger nd rnking foods in order of their ility to llevite hunger over time. Sensory evlution stndrd procedures (20,30) were followed where sujects lso cted s pnelists. Sensory evlution lso uses VAS for ssessing food chrcteristics such s texture or color or for mesuring degree of liking (20). Pnelists were seted in isolted sensory ooths for test mel consumption, nd test mels were presented ccording to the stndrd method. The min purpose of this study ws to determine if differences in stiety of similr whole-grin foods, three ulgur products processed in different wys nd high-mylose rice, could e mesured nd if significnt difference in level of stiety existed etween the different mels. Mterils nd methods The vlidted within suject repeted mesures design nd the VAS methods used y Holt nd coworkers (15) nd Brkeling nd coworkers (1) were comined with sensory evlution techniques to develop the following method. Suject Selection Helthy volunteers ge 18 to 50 were recruited, screened y n interview, nd they completed suject selection questionnire. The screening process enled the selection of 21 helthy mles nd femles with ody mss index (BMI) of nd one suject with BMI of Sujects were excluded if they smoked, were clssified s restrined eters y the questionnire, if they hd medicl or helth condition, or were tking ny prescriptive mediction tht would ffect the purposes of the study. Sujects were excluded if they were currently on, or hd een on, weight-loss diet during the lst CEREAL FOODS WORLD / 15

2 6 months, if they were consuming less thn three mels per dy, if they found the food uncceptle, or hd n llergy to ny ingredient. Prticipnts were sked to mintin their norml regulr exercise. Sujects lso completed three-fctor eting questionnire, which ws tool used to evlute person s level of dietry restrint, disinhiition nd perceived hunger (31), nd suitility for sensory evlution. Selected sujects hd low dietry restrint (the tendency to limit food intke to control ody weight) nd disinhiition (the tendency to overindulge when food is redily ville). Test Food The test food ws mde y methods developed during 3-yer project on ulgur processing nd qulity (9). The Turkish ulgur smple ws highqulity durum ulgur from Turkey. The Austrlin durum whet ulgur smples were either stemed or oiled during the processing nd ll other processing steps were identicl. The milled rice smple ws high-mylose Austrlin white rice vriety, Doongr, which is mrketed s hving lower glycemic index thn most other rice. No significnt differences in energy content etween the four smples were detected, nd 170 g of the test foods contined 1,595 ± 125 kj. The energy content of the ulgur smples ws detected with LECO-AC350 isoperil clorimeter. The test mel composition ws stndrdized for ll four test mels, with only the min crohydrte component differing in ech, either ulgur or rice. The three ulgur smples nd the rice smple were prepred s low-ft, low-protein, nd high-crohydrte test mels. The ulgur nd rice used in the test mels were cooked y oiling nd sorption method. The test mel ws developed s type of hot rekfst to ddress pltility. The mel consisted of 170 g of cooked ulgur or rice, plus 30 g of grilled eggplnt, zucchini, tomto, nd pine nuts in equl mounts. Sujects were lso required to consume the 250 ml of wter supplied with the mel. Procedure Fctors tht influence stiety nd re relted to the test mel, including energy density, weight nd volume, mcronutrient composition, prticle size, nd pltility, were ll controlled in the study. A within suject crossover design ws used in which sujects cted s their own control. They were required to ttend one test session per week t the sme time nd dy of ech week for four consecutive weeks, under s similr conditions s possile (15,21,26). Ech suject consumed ll four test mels in rndom order, one different mel ech week. The dy efore the test dy, sujects were sked to et n evening mel tht consisted of frozen mel stndrdized t 4,455 kj for men nd 3,112 kj for women. Sujects were instructed to et the evening mel (Tle I) s close to 7pm s possile nd then fst for 10 hr, consuming only wter. On the morning of the test, sujects reported to the tste pnel room, were plced in individul ooths, nd given the test mel. Sujects were required to complete VAS, rting their feelings of stiety efore consuming the test mel. A 100-mm VAS ws used for ech senstion (Fig. 1). Sujects consumed their test mel nd then completed the VAS, rting their feelings of fullness, desire to et, prospective consumption, the plesntness, nd the difficulty in eting the mel (Tle II). Sujects were sked to complete one VAS every 30 min, nd the completed sheet ws plced in the envelope provided efore reding nd completing the next line scle. This methodology ws used to reduce the chnce of sujects referring to their previous rtings. After eting the test mel, sujects selected their lunch from menu provided. Individul lunches, including ll food items, were weighed nd descried nd the dt ws used to confirm tht the sujects were helthy eters. Detils of the type nd mount of food nd drink consumed y sujects were recorded on the lunch menus y the resercher. Sttisticl Anlysis Rnk sum sensory nlysis (30), stiety index (14), nd stiety response curve (re under the curve) methods (15) were used to nlyze results. Rnkings for ech individul t specific times fter eting were clculted from the visul nlogue records nd were dded to chieve rnk sum. F vlues were clculted for the 22 pnelists rnk sum nd criticl vlue clculted. A significnt difference existed if the difference in rnk sum ws greter thn the criticl vlue. 16 / JANUARY-FEBRUARY 2007, VOL. 52, NO. 1

3 The totl re under the curve ws clculted for ech individul suject from his or her hunger nd fullness response curves, ech treted seprtely. The stiety response to food ws quntified s the totl re under the curve from just fter the test mel nd 0 4 hr fter eting the test mel, clculted using the trpezoidl rule (7). Stiety index scores were clculted for ech individul suject for hunger nd fullness nd for ech of the four test foods. The stiety index scores were then otined y dividing the re under the How hungry do you feel right now? curve for the test food, the ulgur smples, y the re under the curve for the reference food (high-mylose rice) nd expressed s percentge with rice 100%. Holt nd coworkers (14) mesured fullness to develop score, which ws relted to white red (100%). One-wy nlysis of vrince ws used to determine if there were ny significnt differences etween the re under the curve vlues nd stiety index scores. Results nd Discussion The energy density rnge (1,470 1,722 kj/100 g) nd prticle size (hlf to wholegrin size) of the four test mels were similr, nd the differences were considered insignificnt within the context of this project. The use of stndrd weight of the test mel (170 g) ment tht weight nd volume effects on stiety were controlled. Pnelists my e influenced y the test mel weight or volume, pltility, nd texture including prticle size. They rted the difficulty to et the test mel s not to e significntly different etween the four mels nd rted low in difficulty to consume. The plesntness rtings for the test mels ( on 0 10 VAS) were determined not to e significntly different from ech other, nd overll, the sujects stted tht the mels were plesnt to consume. Weight or volume, pltility, nd texture re not controlled in most stiety studies ecuse of the rnge of food types usully tested (16). However, sujects in this study were unle to tell whether they were eting ulgur or rice test mels ecuse of the similr ppernce, color, tste, nd texture of the mel. Rnking of mels for hunger t specific time fter consumption were clculted ccording to Stndrds Austrli, sensory exmintion of foods (AS ). The 22 pnelists rnkings of the four mels (highest hunger rnk ws given vlue of 4 nd the lest hunger given vlue of 1) were totled to otin rnk sum. If the rnk sum difference etween the mels ws greter or equl to criticl vlue of 16.85, then there is significnt difference etween the mels for stiety. Holt nd Brnd-Miller (13) chose to mesure stiety on the sis of mesuring when hunger returns, fter the consumption of high-wter foods, nd from this mesurement they mde prediction of the degree of fullness t 2 hr fter eting. High-stiety food would e expected to dely hunger for s long s possile. In the current study, stiety ws mesured every 30 min nd up to 4 hr fter the test mel ws consumed on VAS (Fig. 1). Meningful mesurements could e mde if stndrd time within hr rnge ws used (Fig. 2). Rnk sum for the stemed nd oiled ulgur were significntly different to rice for hunger t 1 nd 1.5 hr fter eting. At 2.5 hr, oiled ulgur ws significntly different to rice (criticl vlue greter thn 16.75), however, stemed ulgur, while still hving the second lowest hunger rnking, differed from rice y vlue of 15. At 4 hr, ll ulgur mels rnked lower thn the rice mel, nd t the efore lunch period, oiled ulgur rnked the lowest ut ws not significntly different to rice (criticl vlue of 15). The 22 sujects were significntly less hungry fter consuming oiled ulgur rther thn the other ulgur mels or rice for t lest 2.5 hr. The possile reson oiled ulgur provides greter stiety my e ecuse the more solule strch leches during oiling, leving ulgur tht is higher in protein nd with possily higher resistnt strch, s percent of the whole grin. The ulgur qulity project (20) showed tht leched solids cn rnge from 1 mg/g of the originl grin to 7 mg/g with incresed oiling time to 30 min, depending on the originl grin size nd hrdness. Differences in the men stiety index scores nd re under the curve vlues for the 30 min to efore lunch time frme (Tle III) indicted tht the ulgur smples provided greter stiety thn tht for high-mylose rice. The rnking for re under the curve over 4 hr nd stiety index visul nlogue question How hungry do you feel right now? resulted in lest hungry to most hungry rnk of oiled ulgur, stemed ulgur, Turkish ulgur nd rice, respectively. The rnking for How full do you feel right now? resulted in most full to lest full rnk for oiled ulgur, stemed ulgur, Turkish ulgur, nd rice, respectively. VAS results of the 22 sujects were comined, nd the men scores for rting Fig. 1. Visul nlogue scle for question, How hungry do you feel right now? Rnk Sum Rnk Sum for Hunger 1hour 1.5 hours 2.5 hours 4 hours Before lunch oiled B stemed B Fig. 2. Rnk sum of 22 sujects for the rnking of How hungry do you feel right now? Rnk sums tht do not hve common superscript re significntly different t P < Test Time rice Turkish B CEREAL FOODS WORLD / 17

4 feelings of hunger compred the stiting effect from oiled ulgur nd high-mylose rice. Boiled ulgur rted lower thn did rice for hunger from 1.5 hr until the recorded efore lunch rting (Fig. 3). In this study, the fctors known to ffect stiety, the physicl chrcteristics of the ulgur nd rice, such s energy density, weight nd volume, mcronutrient composition, prticle size, nd pltility, were controlled. Other fctors tht my e contriuting to stiety differences of the whole-grin ulgur nd rice my e glycemic index (GI), fier, nd resistnt strch. The reserch smples selected nd processed for this study ddressed the GI, fier, nd resistnt strch issues. Holt nd coworkers (15) found tht the GI of red did not impct the fullness response, ut whole-grin foods my not show the sme response s red. In contrst, Red nd Kouris-Blzos (24) report tht low glycemic index food my dely the return of hunger, nd therefore, influence stiety. Tetens nd Rice (32) lso found high-mylose rice ws potentilly more stisfying thn low-mylose rice. Bulgur is in the low GI rnge of less thn 55. High-mylose rice, Doongr, ws selected s the reference food ecuse it hs lower GI of 56 when compred with other rice (in Austrli, to e leled low GI, food must e less thn 55). High-mylose rice ws chosen ecuse it hs lower GI thn other white rice, nd therefore, would e closer to the test food. Dietry fier is known to positively ffect stiety, nd ulgur is lso known to hve greter dietry fier content thn the highmylose rice. In terms of diet, fier nd resistnt strch re relted. Resistnt strch type 1 or physiclly inccessile strch ecuse of entrpment in the plnt tissue mtrix my e fctor for ulgur s Hunger rting score Chnge in Stiety Over Time Time whole-grin product. Strch tht undergoes geltiniztion nd retrogrdtion process, s descried y BeMiller nd Whistler (3), is known s resistnt strch type 3 nd is present in rice nd ulgur ut t very low levels, pproximtely 1%, so it should not hve significnt influence. Conclusions There ws no significnt difference in difficulty, time tken to et, nd plesntness of the different test mels mde from ulgur or rice. This confirmed tht pltility ws effectively stndrdized for ll test mels. This study hs found differences in stiety, prtly ecuse of the control of density, prticle sizes, nd pltility of the test food. The re under the curve technique for testing equl portions of ulgur nd rice gve consistent trends nd ulgur rted lower thn rice for hunger from 1.5 hr until the recorded efore lunch, ut the difference ws not significnt. Differences in the men stiety index scores nd re under the curve vlues suggest tht the ulgur provided greter stiety thn tht of the rice. The uniqueness nd significnce of this reserch is the comintion of sensory evlution techniques nd rnking food for the chrcteristics tested. Significnt stiety differences were otined in mels from very similr grin. The difference in ulgur ecuse of processing ws le to e mesured nd different whole grins, i.e., rice mel nd whet-sed ulgur mel, showed significnt differences for stiety. Bulgur when oiled or stemed during processing gve significntly higher stiety or lower rnk sum for hunger thn the rice t 1 nd 1.5 hr. Bulgur, when oiled during processing, gve significntly higher stiety t 2.5 hr thn the rice. Fig. 3. Men stiety rting score of 22 sujects over time for oiled ulgur nd rice mels for the question How hungry do you feel right now? Acknowledgment We wish to thnk the Grins Reserch nd Development Corportion for funding this study nd Mustf Byrm, Gzintep University, Turkey, for ssisting with this reserch. References 1. Brkeling, B., Grnfelt, Y., Bjorck, I., nd Rossner, S. 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