World Journl of Diry & Food Sciences 4 (1): 41-45, 29 ISSN 1817-38X IDOSI Pulictions, 29 Supplementtion nd Cooking of Perl Millet: Chnges in Protein Frctions nd Sensory Qulity Mh A.M. Ali, Adullhi H. El Tiny, Ism A. Mohmed nd Elfdil E. Biker Deprtment of Food Science nd Technology, Fculty of Agriculture, University of Khrtoum, Khrtoum North 13314, Shmt, Sudn Astrct: Perl millet nd soyen flour were used in this study. Investigtion showed tht the mjor frction of perl millet protein ws the prolmin followed y gloulin nd glutelin, while tht of soyen ws the gloulin followed y glutelin nd lesser mounts of lumin nd prolmin. Cooking of perl millet or soyen ws found to decrese the gloulin nd true-prolmin frctions, while the prolmin-like, true-glutelin nd insolule protein were incresed. The lumin frction of cooked perl millet flour incresed, while tht of soyen flour decresed. The glutelin-like frction of cooked perl millet flour decresed, while tht of soyen flour ws incresed. Supplementtion of perl millet flour with soyen protein ws found to increse significntly the gloulin frction nd decresed the true-prolmin nd true-glutelin, while cooking of perl millet flour supplemented with soyen protein ws found to decrese the gloulin nd true-prolmin frctions, ut incresed the true-glutelin frction nd insolule protein. The gloulin frction of cooked perl millet flour supplemented with soyen protein ws higher thn tht of cooked flour. Sensory evlution of loclly processed perl millet supplemented with 5, 1 nd 15% soyen protein showed high vlue for colour nd low vlue for flvor compred to the unsupplemented perl millet. The tste of the supplement processed with 5 nd 1% soyen protein showed the sme vlue s tht of the control, while the texture showed high vlue. Bsed on the judgement of the pnelists, the processed supplement (15% soyen) protein showed low tste vlue nd the sme vlue s tht of the control for its texture. Key words: Millet Cooking Soyen Supplementtion Protein frctions Sensory qulity To improve the nutritionl qulity of cerel-sed trditionl diets in Afric, the use of soyen (Glycine mx L., Merrill) flour s protein supplement hs often een suggested. Soyen hs recently ecome populr in the West Africn su-region due to the high protein content nd qulity nd it cn e effectively used in trditionl cerel-sed wening foods s n cceptle protein supplement [3]. Perl millet proteins were seprted into six frctions; gloulin, lumin, true- prolmin, prolmin-like, glutelin-like nd true-glutelin. Prolmins constitute the mjor protein frction in perl millet followed y glutelins. They were constituted out 75% of the totl protein frctions [4]. The mjor portion of proteins in ens ws the gloulins followed y glutelins nd lesser mounts of lumin nd prolmins [5]. The lumin nd gloulin frction contin contin higher levels of the mino cid lysine s ws reported y Wu nd Wll [6]; hence, soyen protein qulity is ttriutle to INTRODUCTION Perl millet (Pennisetum glucum L.) is consumed s stple food y lrge sections of the popultion in Indi nd Afric nd, recently, ttempts hve een mde to comine high grin yield with good nutritionl qulity. The nutritionl properties of perl millet hve received more ttention thn those of the other common millets, ecuse it is the lrgest-seeded nd most widely grown type [1]. Millet is usully ground for feeding to nimls other thn poultry nd it is very importnt in humn diets, prticulrly those of the poorest people of the semi-rid tropics. The protein qulity of perl millet is low in the levels of lysine nd tryptophn; hence, there is growing emphsis on the improvement of protein quntity nd qulity in cerel crops. Therefore, ttempts hve een mde to fortify these cerels with legumes or other cerels to mke nutritionlly superior nd cceptle products [2]. Corresponding Author: Elfdil E. Biker, Deprtment of Food Science nd Technology, Fculty of Agriculture, University of Khrtoum, Khrtoum North 13314, Shmt, Sudn 41
the higher levels of the lumin plus gloulin frctions, ws isolted from extrctnts y centrifugtion t 3 which re rich in lysine. Pulses role, s protein rpm for 15 min. For ech solvent the superntnts were supplements in the diets sed on cerels nd millets, is comined to give the totl extrct. Nitrogen content of well recognized [7]. This indictes tht the nutritionl ech frction ws determined y the micro-kjeldhl vlue nd the protein vilility of perl millet flour method [9]. The residue left fter extrction ws nlyzed would e expected to increse y incresing the lysine for nitrogen content [9]. level due to the increse in the gloulin frctions s result of supplementtion with soyen protein. Sensory Evlution: A trined pnel of ten memers, Therefore, the ojective of the present investigtion ws composed of dult mles nd femles, ws ssigned to to study the effect of supplementtion with soyen determine preference of processed perl millet flour s protein nd cooking on protein frctions nd sensory control nd when supplemented with 5, 1 nd 15% qulity of perl millet flour. soyen protein for colour, flvor, tste nd texture. They were scored on scle of 1-4 ( 1 = poor, 2 = good, 3 = very MATERIALS AND METHODS good nd 4 = excellent ). The order of presenttion of the smples ws rndomized. To determine if the oserved Mterils: Soyen flour ws otined from USA mrket differences in judges responses were sttisticlly nd perl millet cultivr Dempy seeds ws otined significnt, the men scores were nlyzed y Duncn s from El Oeid Reserch Sttion, Sudn. The grins were multiple rnge test. hrvested during the seson 26/27. The grins were clened from dust nd foreign mterils nd roken Sttisticl Anlysis: Ech determintion consisted of grins. The clen grins were milled into fine powder to three seprte smples, which were nlyzed nd the pssed.4 mm screen. The flour ws kept into nylon figures were then verged. Dt were ssessed y gs nd plced into smll clen ottles t 4 C in nlysis of vrince (ANOVA) [1] nd y the Duncn s refrigertor for further nlysis. Unless otherwise stted multiple rnge test with proility P.5. ll chemicls nd regents used in this study re of nlyticl grde. RESULTS AND DISCUSSION Processing of Supplementednd Unsupplemented Flour: Effect of Cooking on Protein Soluility Frctions of Perl Three levels of soyen flour were dded to increse perl Millet nd Soyen Flour: The percentges of protein millet protein y 5, 1 nd 15 %. Ech mount ws curried frctions of uncooked nd cooked perl millet cultivr re nd dded to perl millet ccording to Person s squre. shown in Tle 1. The gloulin frction of uncooked perl The flour of the smples ws suspended in wter millet cultivr ws found to e 31.3% nd decresed (1:1 W/V) nd oiled in oiling wter th for 2 min, significntly (P.5) to 15.7% fter cooking. The the cooked gruel ws then dried t 65 C nd reground to lumin of uncooked perl millet ws found to e 1.% pss.4 mm screen. The smples were kept in smll nd incresed to 1.8% fter cooking. The true-prolmin ottles t 5 C in refrigertor for further nlysis. frction ws 37.7% for uncooked perl millet nd decresed significntly (P.5) to 29.5% fter cooking. Protein Frctiontion: The nitrogen from the deftted The prolmin-like ws incresed from 5.6 to 7.3% fter treted nd untreted leves ws extrcted stepwise y cooking. The glutelin-like ws 4.4% of uncooked perl series of solvents ccording to Lndry nd Moureux millet nd decresed to 4.% fter cooking. The true- [8] technique. Aout 3.5 g of ech smple ws kept in glutelin ws 2.4% of uncooked perl millet nd incresed suspension with 35 ml of extrctnt y mgnetic stirring significntly (P.5) to 38.4% fter cooking. The in 5 ml centrifuge tues, the protein ws frctionted insolule protein incresed significntly (P.5) from step wise t 2 C using.5 M NCl to otin gloulin, 2.1 to 5.% fter cooking. The results otined indicted distilled wter to otin lumin, 6% ethnol to otin tht there were significnt differences mong the vlues prolmin, 6% ethnol with.6% 2-mercptoethnol of the protein frctions of perl millet fter cooking. (2ME) to otin the G1-glutelin, orte uffer (ph 1) with Prolmins constituted the mjor protein frction in perl.6% 2ME nd.5m NCl to otin G2-glutelin nd orte millet nd this ws considered nutritionlly undesirle uffer (ph 1) with.6% 2-ME nd.5% sodium dodecyl ecuse it ws shown to e low in lysine nd tryptophn sulphte (SDS) to otin G -glutelin. The solid mteril content. Neucere nd Sumrell [11] reported tht the low 3 42
Tle 1: Effect of cooking on protein content nd frctions (%) of perl millet nd soyen flour Smples Tretment Protein content Gloulin Alumin True prolmin Prolmin like Glutelin like True glutelin Insolule protein Totl protein recovered Perl millet Uncooked 13.67 (±.6) 31.28 (±.42) 1.3 (±.16) 37.68 (±.48) 5.6 (±.56) 4.38 (±.24) 2.35 (±.42) 2.14 (±.9) 12.45 (±.28) Cooked 14.15 (±.5) 15.73 (±.34) 1.82 (±.26) 29.45 (±.46) 7.29 (±.52) 4. (±.37) 38.37 (±.38) 5.4 (±.9) 11.71 (±.14) Soyen Uncooked 48.12 (±.9) 82.83 (±.12) 1.27 (±.8) 3.59 (±.24).69 (±.9) 1.32 (±.12) 9.7 (±.8) 3.3 (±.5) 12.43 (±.6) Cooked 48.13 (±.5) 32.68 (±.11).74 (±.5) 3.32 (±.24) 2.13 (±.16) 4.42 (±.11) 54.13 (±.12) 4.7 (±.5) 11.49 (±.5) Tle 2. Effect of supplementtion of perl millet with soyen protein t different levels (5%, 1% nd 15%) on protein frctions (%) Supplementtion level (%) Protein content Gloulin Alumin True prolmin Prolmin like Glutelin like True glutelin Insolule protein Totl protein recovered 13.67 (±.6) 31.28 (±.42) 1.3 (±.16) 37.68 (±.48) 5.6 (±.56) 4.38 (±.24) 2.35 (±.42) 2.14 (±.9) 12.45 (±.28) 5 19.51 (±.5) 53.17 (±.28) 1.2 (±.12) 19.15 (±.59) 2.93 (±.22) 3.15 (±.) 21.28 (±.17) 1.89 (±.5) 12.77 (±.11) c c c 1 24.58 (±.6) 63.14 (±.21) 1.12 (±.9) 12.46 (±.46) 1.51 (±.32) 2.63 (±.17) 19.61 (±.16) 2.22 (±.1) 12.69 (±.13) 15 3.92 (±.9) 69.78 (±.17) 1.47 (±.6) 9.6 (±.63) 2.1 (±.14) 2.64 (±.1) 15. (±.19) 2.5 (±.9) 12.45 (±.13) c c content of lysine is ttriuted to the high content of gloulin frction of perl millet incresed significntly prolmin in most vrieties. Cooking decresed the (P.5) s the level of soyen protein supplement gloulin nd true-prolmin frctions while true-glutelin incresed nd ws found to e 53.2, 63.1 nd 69.8% when frction incresed. The increment in glutelin fter cooking supplemented with 5, 1 nd 15% soyen protein, ws reported in cerels y Ar nd El Tiny [12], Yousif respectively. The lumin frction ws 1.2 nd 1.1% nd El Tiny [13] nd Fgeer nd El Tiny [14]. The when supplemented with 5 nd 1% soyen protein, percentges of protein frctions of soyen flour respectively, ut incresed to 1.5% when supplemented efore nd fter cooking re shown in Tle 1. The with 15% soyen protein. The true-prolmin frction gloulin nd lumin frctions of uncooked soyen decresed significntly (P.5) with incresing the level flour were 82.8 nd 1.3% nd decresed significntly of soyen protein supplement nd it ws found to e (P.5) to 32.7 nd.7%, respectively fter cooking. The 19.2, 12.5 nd 9.1%. The prolmin-like ws 2.9, 1.5 nd true-prolmin frction ws 3.6% for uncooked soyen 2.% when supplemented with 5, 1 nd 15% soyen nd decresed to 3.3% fter cooking. The prolmin-like, protein, respectively. The glutelin-like ws 3.2% when glutelin-like, true-glutelin nd insolule protein were supplemented with 5% soyen protein. However, it incresed significntly (P.5) from.7, 1.3, 9.7 nd decresed to 2.6% when supplemented with 1 nd 15% 3.%, respectively to 2.1, 4.4, 54.1 nd 4.1%, respectively soyen protein. The true-glutelin frction decresed fter cooking. The dt otined indicted tht the mjor significntly (P.5) with incresing the level of protein frction of soyen flour ws the gloulin, soyen protein supplement nd ws found to e 21.3, followed y glutelins nd lessor mounts of lumins 19.6 nd 15.%, while the insolule protein ws nd prolmins. These results re in greement with those incresed. The results otined indicted tht the gloulin reported y Nikokoyris nd Kndylis [5], Nugdllh nd frction of perl millet ws incresed s result of El Tiny [15] nd El Fiel, El Tiny nd El Sheikh [16]. supplementtion followed y significnt decrese in Cooking of soyen flour decresed the lumin nd true-prolmin nd true-glutelin frctions. The lumin plus gloulin frctions, the decrese in such frctions ws gloulin frction hd higher level of the mino cid found to e ccompnied y significnt increse in true- lysine s ws reported y Wu nd Wll [6]. As result of glutelin frction. The results otined re in greement supplementtion with, the nutritionl vlue of perl millet with those reported y Nugdllh nd El Tiny [15] for would e expected to increse y incresing lysine level two cultivrs of cowpe nd El Fiel, El Tiny nd El Sheikh due to the increse in the gloulin frction. The [16] for f ens fter cooking. percentges of protein frctions of cooked perl millet cultivr supplemented with 5, 1 nd 15% soyen protein Effect of Supplementtion nd Cooking of Perl Millet on re shown in Tle 3. The gloulin frction incresed Protein Soluility Frctions: The percentges of protein significntly (P.5) fter cooking with incresing frctions of perl millet cultivr supplemented with 5, 1 soyen protein level nd ws found to e 22.6, 27.5 nd nd 15% soyen protein re shown in Tle 2. The 31.6% when supplemented with 5, 1 nd 15% soyen 43
Tle 3: Effect of cooking of perl millet supplemented with soyen protein t different levels (5%, 1% nd 15%) on protein frctions (%). Supplementtion level (%) Protein content Gloulin Alumin True prolmin Prolmin like Glutelin like True glutelin Insolule protein Totl protein recovered 14.15 (±.5) 15.73 (±.34) 1.82 (±.26) 29.45 (±.46) 7.29 (±.52) 4. (±.37) 38.37 (±.38) 5.4 (±.9) 11.71 (±.14) 5 2.6 (±.5) 22.63 (±.24) 1.12 (±.1) 16.82 (±.55) 5.87 (±.21) 6.5 (±.14) 44.79 (±.26) 2.76 (±.9) 1.48 (±.2) c c c c c 1 25.74 (±.6) 27.52 (±.19) 1. (±.14) 8.95 (±.24) 3.15 (±.29) 6.91 (±.2) 5.4 (±.22) 3.94 (±.9) 11.52 (±.9) 15 31.58 (±.5) 31.57 (±.16).93 (±.12) 5.99 (±.36) 3.19 (±.13) 6.13 (±.17) 51.1 (±.18) 2.96 (±.6) 11.88 (±.15) c c Tle 4: Sensory Qulity (cceptility) of processed perl millet flour supplemented with soyen protein t different levels (5%, 1% nd 15%). Supplementtion level (%) Colour Flvour Tste Texture 1.7 (±.26) 3.5 (±.27) 2.85 (±.29) 2.15 (±.26) 5 2.6 (±.18) 2.35 (±.23) 2.8 (±.21) 3.2 (±.2) 1 3. (±.18) 2.35 (±.22) 2.35 (±.15) 2.85 (±.18) 15 2.7 (±.28) 2.25 (±.26) 2. (±.29) 1.8 (±.24) Vlues re mens (± SD). Mens not shring common superscript letter in column re significntly different t P.5 s ssessed y Duncn s multiple rnge test protein, respectively. The results otined were lower Effect of Soyen Protein Supplementtion on thn those of uncooked perl millet supplements, ut higher thn those of cooked unsupplemented perl millet flour. The results indicted tht the nutritionl vlue of Sensory Qulity of Processed Perl Millet Flour: Tle 4 shows the men scores for colour, flvor, tste nd texture of the control perl millet flour cooked perl millet would e expected to increse y nd processed one supplemented with 5, 1 nd 15% incresing the lysine level due to the increse in the soyen protein. The sensory preference of the gloulin frction s result of supplementtion with colour of the supplements scored high vlue while soyen protein. The lumin frction ws 1.1, 1. nd tht of the flvor ws scored low vlue when.9% fter cooking when perl millet ws supplemented compred to the control. The results otined with 5, 1 nd 15% soyen protein. The true-prolmin indicted tht the mjority gve low cceptility frction decresed significntly (P.5) fter cooking for the flvor of the processed supplements compred with incresing the level of soyen protein nd ws found to e 16.8, 9. nd 6.%. The results otined were to the control. The result ws in greement with tht lower thn those of uncooked perl millet supplemented reported y Wolf [17] who reported tht rw soy with soyen protein. The prolmin-like frction fter flours nd grits hve chrcteristic flvor cooking ws 5.9% when perl millet ws supplemented with 5% soyen protein nd decresed significntly (P.5) to 3.2% when perl millet ws supplemented with 1 nd 15% soyen protein. The glutelin-like ws 6.5, 6.9 nd 6.1% fter cooking of perl millet supplemented with 5, 1 nd 15% soyen protein, respectively.the true-glutelin frction incresed significntly (P.5) fter cooking with incresing the level of soyen protein supplement nd ws 44.8, 5. nd 51.1% for the supplements, respectively. The results otined were higher thn those of uncooked perl millet supplements. The insolule protein ws 2.8, 3.9 nd 3.% fter cooking of perl millet supplements (5, 1 nd 15%). The results were higher thn those of uncooked perl millet supplements. It ws cler tht gloulin nd true-prolmin frctions decresed significntly (P.5) fter cooking of perl millet even fter supplementtion while the true-glutelin frction incresed when compred with uncooked perl millet supplements (5, 1 nd 15%). uncceptle in mny foods. The sensory preference of the processed supplements i.e. 5 nd 1% soyen protein for the tste ws similr to tht of the control ut scored lower vlue when supplemented with 15% soyen protein. For the texture of the processed supplements ws similr to tht of the control especilly when the flour ws supplemented with 15% soyen protein. However, it scored high vlue when supplemented with 5 nd 1% soyen protein. The results otined showed tht the mjority preferred the processed supplements contined 5 nd 1% soyen protein especilly for tste nd texture more thn the supplement contined 15% soyen protein s compred to the control. This ws chieved with significntly incresed protein content nd qulity over the unsupplemented perl millet. Therefore, soyen protein would e expected to e used s functionl ingredients supplying tste, texture, colour nd other properties to vriety of foods. 44
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