foods Artile Effet of Soking nd Rosting on the Physiohemil nd Psting Properties of Soyen Flour Aurelie Solnge Ntso Agume 1, Niols Ynou Njintng 2, * nd Crl Moses F. Mofung 3 1 Deprtment of Food Sienes nd Qulity Control, Institut Universitire de Tehnologie (IUT), University of Ngoundere, P.O. Box 455, Ngoundere, Cmeroon; urelie_gume@yhoo.fr 2 Deprtment of Biologil Sienes, Fulty of Siene, University of Ngoundere, P.O. Box 454, Ngoundere, Cmeroon 3 Deprtment of Food Sienes nd Nutrition, ENSAI, University of Ngoundere, P.O. Box 455, Ngoundere, Cmeroon; mofung@yhoo.om * Correspondene: njintng@yhoo.fr; Tel.: +237-699-87-979 Ademi Editor: Anthony Frdet Reeived: 16 Septemer 216; Aepted: 17 Jnury 217; Pulished: 9 Ferury 217 Astrt: The effets of soking nd rosting on the physiohemil nd psting properties of soyen flour were evluted. Soyen seeds were soked overnight in tp wter for 72 h, hnd dehulled, dried, nd prt of the smple ws rosted. Rosted nd unrosted soy ens were milled into flour nd nlyzed. The results showed tht the totl rohydrtes (22.8 27.9 g/1 g), the sh ontent (3.5 3.6 g/1 g), nd the totl polyphenols (.29.51 g/1 g) did not signifintly hnge during oth the soking nd rosting proesses. However, the totl proteins (35.8 46. g/1 g) nd lipid ontents (21.4 29.5 g/1 g) were signifintly (p <.5) ffeted only y soking, with derese in totl protein nd n inrese in lipid ontents. Phytte ontent (.22.26 g/1 g) deresed signifintly (p <.5) only with rosting. The tnnins (.1.3 g/1 g) nd solule proteins (4. 29. g/1 g) signifintly (p <.5) diminished with oth tretments. There ws signifint inrese in the lest geltion onentrtion (2 3 g/1 ml), derese in the swelling power (1.3 2. ml/ml), nd onsequently, redution in the visosity (rnge pek visosity 18 21 P) of the flour slurry fter soking nd rosting. All these qulities needed for produing nutritious flour for infnts highlighted the effiieny of these endogenous tehnologies. Keywords: soyen flour; soking; rosting; physiohemil properties; visosity 1. Introdution Soyen is n importnt soure of proteins (4%), lipids (2%), minerls (5%), nd B vitmins for humn nutrition [1]. There is inresing evidene tht the onsumption of soyen produts redues ner, lood serum holesterol, osteoporosis, hroni renl disese, hert disese, oxidtive stress, nd others [1 3]. The helth enefits of soyen produts hve indued n inrese in the demnd for ens. In this respet, the world prodution of soyens hs signifintly inresed in the lst dede, rising from 2 million metri tons in 25 to 324 million metri tons in 216 [4]. Though the 215 nnul prodution is very low (less thn 3 million metri tons) in Afri, in this re of the world, soyen plys n importnt role in infnt nutrition. In prtiulr, soy flour is used to fortify trditionl erel-sed foods [5,6]. Soyen-fortified mize hs een the sujet of iohemil, nutritionl, sensory, rheologil [7,8], nd storge investigtions. Egounlety nd Syrief reported tht the ddition of 25% soyen tempe powder to Ogi ( fermented mize porridge) overme the tryptophn nd lysine defiieny in mize, nd gretly improved the protein iologil vlue of Ogi, without ffeting the orgnolepti properties of the porridge [9]. Foods 217, 6, 12; doi:1.339/foods6212 www.mdpi.om/journl/foods
Foods 217, 6, 12 2 of 1 The mjor hllenges in using soyen flour in infnt food re the elimintion of nti-nutrients, oligoshrides, nd eny flvor, nd the redution of the visosity of the resulting porridge. Soking nd rosting hve een pplied to meet these ojetives [1,11]. Rosting for 2 min t 1 C ws reported to inhiit 9% of trypsin inhiitors tivity in soyen flour. It hs een reported tht the pplition of rosting hieved plesnt flvor in soy en [12]. Bik nd Hn reported signifint redution of rffinose, versose, nd sthyose during fermenttion nd rosting of soyen [11]. They eqully reported tht rosting indued greter inrese in protein digestiility of soyen thn fermenttion. Shin et l. reported inresed ntioxidnt tivity nd in vitro protein digestiility in rosted soy flour [13]. In trditionl households, the ens re soked for 1 3 dys, during whih some miroil tivities re tivted, leding to improvement of the nutritionl qulity of the resulting flour. Reent investigtions reveled positive effet of long-time soking in reduing the nti-nutrients nd the visosity of mize flour, ut this vried with soking time [14]. In ddition, there ws signifint intertion of soking nd rosting on the nutritionl nd psting properties of mize flour [14]. However, this hs not yet een investigted in soyen flour. This study ims to determine the intertion effet of soking nd rosting on some physiohemil nd psting properties of soyen flour. 2. Mterils nd Methods 2.1. Smpling of Soyen nd Prodution of Soyen Flour The soyen seeds used in this study were purhsed from lol mrkets in Ngoundere, Cmeroon. The dried seeds (moisture ontent 11%) were refully lened nd sorted out to remove defetive nd smll-sized seeds so s to otin len seeds of uniform size. The lened seeds were then proessed into flour, s shown in Figure 1. The seed smple ws divided into four susmples, whih were steeped in tp wter (2 kg/8 L) t mient temperture (25 ± 4 C) for, 24, 48, or 72 h. Soked seeds were mnully dehulled, spred in single lyer on luminum rks, nd dried t n verge temperture of 4 ± 2 C for 1 dy in gs dryer. The dehulled susmples were eh further divided into two susmples, from whih one ws rosted t 11 C for 1 min, nd the seond ws left unrosted. Eh of the resulting eight susmples ws then milled into fine flour using hmmer eletri grinder (Cultti, Polymix, Frne) equipped with sieve of dimeter 25 µm meshes. Flours so produed were seled in polyethylene gs nd stored t 4 C until required for nlysis. 2.2. Chemil Anlysis of Soyen Flours 2.2.1. Determintion of the Proximte Composition nd Some Phytohemils Assoition of Offiil Anlytil Chemists (AOAC) methods were used to determine the moisture, rude ft, nd sh ontents of the flours [15]. Moisture ontent ws determined y the diret oven drying method on 1 g of smple t 15 C for 24 h to onstnt weight. Ash ws determined s the residue of ininerted flour (15 g) in ruile t 55 C; rude ft ws determined y using the Soxhlet extrtion method, with hexne s solvent. Totl protein (N 6.25) ws nlyzed y the Kjeldhl method [16], while totl rohydrte ws determined y spetrophotometri method using phenol fter digestion in onentrted sulfuri id [17]. Phyti id, totl phenoli nd tnnin ontents were determined s reently reported [18]. Phyti id ws extrted in 1.2% HCl solution ontining 1% N 2 SO 4 nd quntified sed on the formtion of omplex with Fe(III) ion t ph 1 2. Phenols were extrted in 8% ethnol followed y olorimetri quntifition either diretly in the extrt (for totl polyphenol determintion) or fter preipittion of tnnins using polyvinylpyrrolidone (for non-tnnin polyphenol determintion). The tnnin ontent of the smple ws lulted s differene etween totl polyphenol nd non-tnnin polyphenol ontents in the extrt. Totl phenoli nd tnnin ontents were expressed s glli id nd tnni id equivlent, respetively.
Foods 217, 6, 12 3 of 1 Foods 217, 6, 12 3 of 11 Figure 1. Flow digrm for the prodution of soyen flour. Figure 1. Flow digrm for the prodution of soyen flour. Phyti id, totl phenoli nd tnnin ontents were determined s reently reported [18]. 2.2.2. Phyti Determintion id ws extrted of Some in Physiohemil 1.2% HCl solution nd ontining Psting 1% Properties N2SO4 nd quntified sed on the formtion The wter of omplex sorption with pity Fe(III) ion (WAC) t ph ws 1 2. Phenols determined were t extrted mient in temperture 8% ethnol followed following y the method olorimetri desried quntifition y Kur nd either Singh diretly [19]. in The the oil extrt sorption (for totl pity polyphenol (OAC) determintion) expressed sor grms fter of penut preipittion oil per grms of tnnins of flour using ws polyvinylpyrrolidone determined on 2.5 (for g smple non tnnin perpolyphenol 3 ml oil, determintion). s desried ythe Kur nd tnnin Singh ontent [19]. The of the Lest smple Geltion ws lulted Conentrtion s differene (LGC) ws etween determined totl polyphenol ording nd to the non tnnin method of polyphenol ontents in the extrt. Totl phenoli nd tnnin ontents were expressed s glli id Coffmn nd Gri [2]. The swelling power ws determined following the stndrd method reported nd tnni id equivlent, respetively. y Gujrl nd Rosell [21]. The psting properties of soyen flours were nlyzed on Rpid Viso Anlyzer 2.2.2. Determintion instrument (Te of Some Mster Physiohemil Model, Perten nd Instruments, Psting Properties nd Austrli) s reently reported [14]. Prmeters reorded were pek visosity (PV), hold visosity (HV: minimum visosity t 95 C), finl visosity The (FV: wter visosity sorption t 5 pity C), rek (WAC) down ws visosity determined (PV HV), t mient nd setk temperture visosity following (FV HV). the method desried y Kur nd Singh [19]. The oil sorption pity (OAC) expressed s grms of 2.3. penut Sttistil oil per Anlysis grms of flour ws determined on 2.5 g smple per 3 ml oil, s desried y Kur nd Singh [19]. The Lest Geltion Conentrtion (LGC) ws determined ording to the method of Coffmn Dt were nd expressed Gri [2]. s men The swelling ± stndrd power devition. ws determined Two-wy nlysis following of vrine the stndrd with intertion method ws reported used toy determine Gujrl nd the Rosell effet [21]. of soking The psting ndproperties rosting on of the soyen properties. flours were Where nlyzed the effet on of ftor Rpid ws Viso signifint, Anlyzer Dunn instrument Multiple (Te Rnge Mster test Model, wsperten rriedinstruments, out to further nd determine Austrli) the s reently differenes etween reported two[14]. mens. Prmeters The sttistil reorded nlysis were pek of the visosity otined (PV), dt hold ws visosity rried(hv: out using minimum the Sttgrphis visosity Centurion t 95 C), XVI finl version visosity 16.1.18 (FV: sttistil visosity pkge. t 5 C), rek down visosity (PV HV), nd setk visosity (FV HV). 3. Results 3.1. Proximte Composition nd Some Phytohemils of Soyen Flour Tle 1 shows the effet of soking time nd rosting on the proximte omposition of soyen flour. Generlly, soyen flour is soure of lipids nd proteins, nd the vlues fll within the rnge reported erlier [1,11]. Similrly, the rohydrte nd sh ontents re quite similr to reported vlues [8]. For the effet of tretments on the moisture, sh, strh, nd protein ontents of soyen flours, soking nd rosting indued signifint hnges in most ses.
Foods 217, 6, 12 4 of 1 Tle 1. Proximte omposition (expressed in g/1 g dry weight sis) of soyen flour s ffeted y rosting nd soking time. Prmeters (%) Unsoked Rosted Soyen Flour Soked 24 h Soked 48 h Soked 72 h Unsoked Unrosted Soyen Flour Soked 24 h Soked 48 h Soked 72 h Moisture * 6.9 ±.5, 5.4 ±.5 5.3 ±.3 5.1 ±.5 8.8 ± 1.6 6.8 ±.3 6.9 ±.4 6.7 ±.4 Totl rohydrtes 27. ± 1.1 26.9 ± 1.8 25.1 ± 1.4 24.3 ± 1.8 27.8 ± 1.8 22.8 ± 1.6 27.9 ± 1.8 24.2 ± 1.3 Totl proteins 44.1 ± 2.1, 35.8 ± 3.3 37. ± 2.3, 35.5 ± 1.1 46. ± 2.1 43.9 ± 3.3, 37.9 ± 4.3, 35.8 ± 3.3 Crude lipids 21.4 ± 1.4 25.7 ± 1.3,, 28. ± 1.6, 29.5 ± 1.2 22.6 ± 1.1 25.5 ± 1.5,, 25.1 ± 1.8, 27.2 ± 1.2, Ash 3.5 ±.2 3.5 ±.1 3.5 ±.1 3.6 ±.1 3.6 ±.1 3.6 ±.1 3.5 ±.1 3.5 ±.1 Men ± stndrd devition; vlues with different letters within the sme row differ signifintly (p <.5) s determined y Dunn s multiple rnge test (n = 3). * Moisture is expressed sed on fresh weight. Moisture ontent vried from 5.1 g/1 g in rosted soyen soked for 72 h to 8.9 g/1 g in unrosted nd unsoked soyen. The moisture ontent did not vry signifintly with soking time. Menwhile, rosting the soyen led to signifint (p <.2) derese of moisture ontent, from men vlue of 7.2 to 5.7 g/1 g. A similr effet of soking nd rosting on the moisture ontent of mize flour hs een reported [14], suggesting the ehvior does not vry with the sustrte. Sine the moisture ontent of the flour is onsequene of its hygrosopi hrter, it is likely to onlude tht rosting dereses the ility of soyen flour to intert with wter. The low level of moisture in rosted flours proly results from the high temperture (whih elimintes wter more quikly), nd the intermoleulr ross-linking tht might our. The totl protein nd rohydrte ontents rnged from 35.5 ± 1.1 46. ± 2.1 g/1 g dry weight (dw) nd 22.8 ± 1.6 27.9 ± 1.8 g/1 g dw, respetively. The totl rohydrte ontent did not vry signifintly with soking or rosting. However, only soking signifintly influened the protein ontent (p <.4), with soked soyen flours generlly exhiiting lower protein ontent thn rw ones. Loss of solule proteins during soking proly ontriuted to the derese in protein ontent of soyen flour. By soking nd susequent rosting, totl protein ontent ws redued y 23%. Derese in proteins nd totl sugrs during soking nd rosting of mize hs een reported [14,22,23]. However, Bik nd Hn reported lower (1% 7%) inrese in the protein nd strh of rosted nd fermented soyen [12]. The differene is proly due to the fermenttion proess, whih ws solid stte fermenttion with fungus strin Rhizopus oligosporus. In this study, lehing indued loss of solule nutrients, nd the nturl fermenttion involving multiple miroorgnisms with vrile metolisms ould hve ontriuted to the derese in proteins [23,24]. It is inresingly evident from studies tht the drop in protein level inresed with soking time. The redution in proteins during soking vried from 5% for 24 h soking to 22% for 72 h soking. The rude lipid ontent in the soyen flour smples vried etween 21.4 ±.4 g/1 g dw (rosted-unsoked) nd 29.5 ± 1.2 g/1 g dw (rosted-72 h soked). Only soking indued signifint inrese in the lipid ontent of soyen flour (p <.5). Generlly, the rude lipid ontent of soyen flour inresed with soking y 2% 38% in rosted soyen flour nd 13% 2% in unrosted soyen flour. This proly resulted s onsequene of the lehing of solule omponents, using onentrtion of the lipids in the flour. Menwhile, rosting the seeds indued non-signifint inrese in the lipid ontent of the soyen flour y % 11%. An inrese in oil ontent fter rosting hs een reported for erel seeds inluding millet [25], mize [26], nd sesme [27]. The inrese in the rude ft ontent my result from the destrution of ell struture nd the effiient relese of oil reserve [28]. The sh ontent of soyen flour vried from 3.48 3.55 g/1 g dw nd from 3.47 3.59 g/1 g dw for rosted nd unrosted soyens, respetively. The low vlues oserved in this study s ompred to the 6.% previously reported [8] might e result of soking (whih soluilized minerls), or the differene in vriety nd gro-eologil zone of ultivtion. Soking time nd rosting did not use signifint differene in the sh ontent of the soyen flour.
Foods 217, 6, 12 5 of 1 Figure 2 shows the levels in some phytohemils of soyen flour. The totl polyphenol ontent (.29.51 g/1 g dw) did not vry signifintly with soking nd rosting (Figure 2A). However, tnnin (.1.3 g/1 g dw) ontent of the soyen flour deresed generlly, not only with soking, ut lso with rosting (Figure 2B). In similr onditions during 48 h soking nd rosting of mize, there ws 22% derese [14]. The derese in tnnins my result from lehing into the soking wter. In the pst, polyphenols nd tnnins were onsidered s nti-nutrients euse they n interfere nd preipitte proteins, thus reduing their iologil utiliztion. In this respet, the derese in tnnins n e onsidered s positive. However, in reent yers, they hve een given positive onsidertion s dietry ntioxidnts nd helth-promoting phytohemils [26]. In this respet, soyen polyphenols in prtiulr, the isoflnones suh s genistin, iologilly-tive oestrogen-like ompound hve een ssoited with the ntioxidnt tivity of soyen flour [29,3]. It ws expeted tht fermenttion would our s result of soking the soyen seeds, s the polyphenol ontent nd ntioxidnt tivity of soyen flour hs een shown to inrese through the tlyti tion of the β-gluosidse enzyme produed y the miroorgnisms, whih hydrolyzes isoflvone gluosides (isoflvones re minly present in soyen foods in the form of gluoside) nd liertes lipophili glyone. In this respet, solid-stte ioproessing of soyen hs een suggested to produe vlue-dded soyen flour [3,31]. Sine polyphenols my e onsidered positively or negtively, omprtive study needs to e rried out on the ntioxidnt nd protein iologil vlue of thefoods soyen 217, 6, flour 12 otined y the liquid nd solid-stte fermenttion proesses. 6 of 11,7 unrosted rosted,6,4 Totl phenols (g/1g dw),5,4,3,2 Tnnins (g/1g dw),3,2,1 unrosted rosted,1, A Soking time (hours), B Soking time (hours) d d d,3 unrosted rosted Phyttes (g/1g dw),25,2,15,1,5 C, Soking time (hours) Figure 2. Totl (A) polyphenol; (B) tnnin; nd (C) phytte ontents of soyen flour s ffeted y Figure 2. Totl (A) polyphenol; (B) tnnin; nd (C) phytte ontents of soyen flour s ffeted y soking time nd rosting. Brs ering different letters re signifintly different t.5; 3. soking time nd rosting. Brs ering different letters re signifintly different t p <.5; n = 3. DW: dry weight. DW: dry weight. 3.2. Vrition in Solule Proteins nd Sugrs Figure 2C shows the vrition in phytte ontent (.22.26 g/1 g dw), whih signifintly The solule protein nd sugr ontents of soyen flour s influened y the tretment (p <.1) deresed with rosting, while soking hd no signifint effet. This oservtion is in onditions re presented in Figure 3. Generlly, the solule protein (4. ±.3 29. ± 1.9 g/1 g dw) greement with erlier studies, whih reported signifint derese in phytte ontent during ontent deresed signifintly (p <.1) with oth soking nd rosting. In ddition, the solule sugr ontent (3.4 ± 1. 1.6 ±.9 g/1 g dw) deresed signifintly (p <.1) with the soking time, while rosting hd no signifint effet. Rosting indued 33% to 66% derese in solule protein, while the redution due to soking rnged 64% 66% for solule sugrs nd 67% 8% for solule proteins. Egounlety nd Aworh reported the mjor oligoshrides in soyen s surose, rffinose, nd sthyose, with respetive ontents of 4.91 g/1 g dw, 1.22 g/1 g dw, nd 8.41 g/1
Foods 217, 6, 12 6 of 1 soking nd rosting of mize flour [14,23,25,27]. In prtiulr, there ws 15% derese of phyttes in soyen flour during 48 h of soking nd rosting, while in similr onditions, there ws n 18% derese in the phyttes of mize [14]. Contrry to this, studies y Egounlety nd Aworh reported non-signifint hnges in phytte ontent during 12 14 h soking in soyens, owpe, nd ground en [32]. 3.2. Vrition in Solule Proteins nd Sugrs The solule protein nd sugr ontents of soyen flour s influened y the tretment onditions re presented in Figure 3. Generlly, the solule protein (4. ±.3 29. ± 1.9 g/1 g dw) ontent deresed signifintly (p <.1) with oth soking nd rosting. In ddition, the solule sugr ontent (3.4 ± 1. 1.6 ±.9 g/1 g dw) deresed signifintly (p <.1) with the soking time, while rosting hd no signifint effet. Rosting indued 33% to 66% derese in solule protein, while the redution due to soking rnged 64% 66% for solule sugrs nd 67% 8% for solule proteins. Egounlety nd Aworh reported the mjor oligoshrides in soyen s surose, rffinose, nd sthyose, with respetive ontents of 4.91 g/1 g dw, 1.22 g/1 g dw, nd 8.41 g/1 g dw [32]. They reported 2% 26% derese in eh of the oligoshrides during 12 14 h soking of the soyen seeds. A similr derese (16% 34%) ws reported in owpe nd ground en [32]. The more importnt derese oserved in this study is proly result of long soking durtion, whih ould hve indued nturl fermenttion, s demonstrted erlier [14]. In this respet, Egounlety nd Aworh reported 56.8% nd 1% dereses in sthyose nd rffinose, respetively, during 48 h solid stte fermenttion with Rhizopus, while versose disppered totlly [32]. In the sme vein, redutions of 87% nd 53% in soyen solule oligoshrides hve een reported during fermenttion nd rosting, respetively [11]. The sme group lso reported in oth onditions, respetively, 35% nd 96% redutions of solule soyen proteins [11]. Similr redutions in solule oligoshrides nd proteins following rosting nd fermenttion were eqully oserved in other dry legume seeds, suh s hikpes, lentils, nd pes [11]. The redution in solule sugrs nd proteins during fermenttion is Foods 217, 6, 12 7 of 11 proly onsequene of their use for the growing miroorgnisms. Severl other uthors reported n inrese hydrolysis in solule [33]. The proteins differene ndin sugrs the ehvior duringis the proly fermenttion onsequene of erels of s the differene onsequene in the of depolymeristion omposition of through erels enzymti nd legumes. hydrolysis Legumes [33]. re The rih differene soures of insolule the ehvior oligoshrides is proly nd onsequene proteins of s the ompred differene to erels in the [14], omposition nd in this of respet, erels nd do not legumes. need the Legumes initil hydrolysis re rih soures of strh of solule nd oligoshrides proteins to initite ndgrowth. proteins s ompred to erels [14], nd in this respet, do not need the initil hydrolysis of strh nd proteins to initite growth. Solule proteins (g/1g dw) 35 3 25 2 15 1 5 Unrosted Rosted d de de e Solule sugrs (g/1g dw) 14 12 1 8 6 4 2 Unrosted Rosted A Soking time (hours) B Soking time (hours) Figure Figure 3. (A) 3. Solule (A) Solule protein; protein; nd nd (B) (B) Solule sugr sugr ontents of of soyen flour, s ffeted y soking time nd time rosting. nd rosting. Brs Brs ering ering different different letters letters re re signifintly different t t p p < <.5; n = 3. 3.3. Some Physiohemil nd Psting Properties of Soyen Flour 3.3. Some Physiohemil nd Psting Properties of Soyen Flour The Wter sorption pity (WAC) of soyen flour is presented in Figure 4A. The WAC of The Wter sorption pity (WAC) of soyen flour is presented in Figure 4A. The WAC soyen flour rnged 239 313 g/1 g, nd deresed signifintly (p.1) with only rosting. of soyen flour rnged 239 313 g/1 g, nd deresed signifintly (p <.1) with only rosting. Rosting indued 2% to 23% derese in the WAC of soyen flour. These oservtions ontrsted with some reports whih showed either non signifint hnge for mize [14] or n inrese for dry legumes [11], ut re similr to those reported from other studies [34,35]. The soking nd rosting type might hve influened the wter sorption ehvior. Vlues of WAC oserved in the present work re higher (213%) thn vlues reported for soyen flour elsewhere [8]. In ddition, the WAC reported for soyen flour is systemtilly higher thn tht reported for mize nd other erel
Foods 217, 6, 12 7 of 1 Rosting indued 2% to 23% derese in the WAC of soyen flour. These oservtions ontrsted with some reports whih showed either non-signifint hnge for mize [14] or n inrese for dry legumes [11], ut re similr to those reported from other studies [34,35]. The soking nd rosting type might hve influened the wter sorption ehvior. Vlues of WAC oserved in the present work re higher (213%) thn vlues reported for soyen flour elsewhere [8]. In ddition, the WAC reported Foods 217, for 6, soyen 12 flour is systemtilly higher thn tht reported for mize nd other erel 8 of flour 11 (92 151 g/1 g) [8,14]. Wter sortion pity (g H2O/1g flour) 4 3 2 1 Unrosted Rosted Oil Asorption Cpity (g oil/1g flour) 25 2 15 1 5 Unrosted Rosted A B Soking time (hours) Soking time (hours) Swelling power (ml/ml) 2,5 2, 1,5 1,,5 d Unrosted Rosted de d e e Lest Geltion Conentrtion (g flour/1g wter) 35 3 25 2 15 1 5 d Unrosted Rosted d C, Soking time (hours) D Soking time (hours) Figure 4. Vrition in (A) Wter sorption pity; (B) Oil sorption pity; (C) Swelling power; Figure 4. Vrition in (A) Wter sorption pity; (B) Oil sorption pity; (C) Swelling power; nd (D) Lest geltion onentrtion of rosted nd unrosted soyen flour s funtion of soking nd (D) Lest geltion onentrtion of rosted nd unrosted soyen flour s funtion of soking time. Brs ering different letters re signifintly different t p.5; = 3. time. Brs ering different letters re signifintly different t p <.5; n = 3. The most importnt prmeter to ppreite the inrese in the energy density of the flour during Compred tretment to wter is the sorption visosity. Generlly, pity, flours the oilwith sorption high gelling pity power (OAC) exhiited (Figure high 4B) swelling did not hnge ility, signifintly nd the resulting with either slurry soking hd high or rosting. visosity. The In ddition, visomylogrphs the ilityof ofthe soyen flour flour tore ind ndpresented retin oil in (OAC Figure rnge 5. The 165 hnge ± 7 25 in ± the 24visosity g oil/1of g) soyen ws lower slurry sduring ompred heting to the showed ility to indehvior nd retin unhrteristi wter (WACof rnge strh 239 313 solution. g/1 In prtiulr, g flour). the Akuor visosity ndof Animwo unrosted reported soyen slurry similr oservtions did not hnge for soyen signifintly [8]. However, during heting, the swelling proly (Figure s onsequene 4C) signifintly of the (p intertion <.1) diminished of strh with with soking lipid time nd nd its low rosting. strh The ontent. derese In ddition, in swelling the with visosity soking diminished time wsignifintly 1% 25% nd (p < 6% 13%.5) for unrosted with soking, nd nd rosted no differene soyenn flour, e respetively. visulized etween As for urves WAC, for the24, swelling 48, nd deresed 72 h soking. with rosting Similr yoservtions 13% 25%, nd were in mde generl, for 48 the hvisosity soking of ssoited rosted soyen with rosting slurry. indued However, 35% the ehvior redution in swelling of rosted power. unsoked The soyen rnge of ws swelling typil vlues to tht were of strh, 1.3 2. with ml/ml higher lerly identified thn psting tht reported point nd for pek visosity. The psting prmeters of the soyen flours re reported in Tle 2, nd it is evident mize flour [14]. Swelling is hrteristi mostly ttriuted to strh, ut whih interts with other tht rosting of unsoked seeds led to signifint (p <.5) derese in the pek (74%), finl (41%), omponents suh s proteins nd lipids. The redution of swelling might result from the destrution hold (47%), nd rekdown (94%) visosities of the soyen flour slurry. Similr redutions of of strh grnules nd proteins struture through miroorgnism-indued enzymti hydrolysis of visosity ws reported in mize [14] nd lend of mize soyen flour [36]. peptide nd glyosidi onds. Soking nd rosting re importnt trditionl tehnologies pplied to erels nd dry seeds for the prodution of infnt foods. In this respet, geltion is negtive ehvior needed for the flour. The lest geltion onentrtion (LGC, whih expresses the quntity of flour needed per volume to otin gel) is presented in Figure 4D. The higher the LGC, the higher the potentil to produe flour with
Foods 217, 6, 12 8 of 1 high energy density. It ws oserved tht the LGC inresed signifintly (p <.1) with soking nd rosting. While rw soyen flour hd n LGC of 2 g/1 ml, the 72 h soked nd rosted soyen flour exhiited n LGC of 3 g/1 ml, equivlent to 5% inrese. A similr inrese fter 48 72 h soking, lthough lower, ws reported in erel flours [14,25]. The most importnt prmeter to ppreite the inrese in the energy density of the flour during tretment is the visosity. Generlly, flours with high gelling power exhiited high swelling ility, nd the resulting slurry hd high visosity. The visomylogrphs of the soyen flour re presented in Figure 5. The hnge in the visosity of soyen slurry during heting showed ehvior unhrteristi of strh solution. In prtiulr, the visosity of unrosted soyen slurry did not hnge signifintly during heting, proly s onsequene of the intertion of strh with lipid nd its low strh ontent. In ddition, the visosity diminished signifintly (p <.5) with soking, nd no differene n e visulized etween urves for 24, 48, nd 72 h soking. Similr oservtions were mde for the visosity of rosted soyen slurry. However, the ehvior of rosted unsoked soyen ws typil to tht of strh, with lerly identified psting point nd pek visosity. The psting prmeters of the soyen flours re reported in Tle 2, nd it is evident tht rosting of unsoked seeds led to signifint (p <.5) derese in the pek (74%), finl (41%), hold (47%), nd rekdown (94%) visosities of the soyen flour slurry. Similr redutions of visosity ws reported in mize [14] nd lend of mize soyen flour [36]. Foods 217, 6, 12 9 of 11 25 2 Temperture Unsoked Soked 24 h Soked 48 h Soked 72 h 1 9 1 8 Temperture Unsoked Soked 24 h Soked 48 h Soked 72 h 1 9 Visosity (Cp) 15 1 5 8 7 6 Temperture ( C) Visosity (Cp) 6 4 8 7 6 Temperture ( C) 5 2 5 A 4 2 4 6 8 Time (s) 4 B 2 4 6 8 Time (s) Figure Figure 5. Visomylogrph 5. Visomylogrph profiles profiles of (A) of unrosted; (A) unrosted; nd (B) rosted nd (B) soked rosted nd soked unsoked nd soyen unsoked flour. soyen flour. Tle 2. Psting properties of soy flour s ffeted y rosting nd soking time. Tle 2. Psting properties of soy flour s ffeted y rosting nd soking time. Tretments Prmeters Time Pek of of Pek Hold Hold Finl Finl Brekdown Brekdown Set k Set k Rosting visosity soking Soking (h) (h) Visosity (P) visosity Visosity (P) (P) visosity Visosity (P) (P) visosity Visosity (P) (P) visosity Visosity (P) (P) (P) Unrosted Unrosted 21 ± 1 91 ± 1 13 ± 3 119 ± 1 12 ± 1 24 21 18 ± ± 1 2 e 91 ± 12 1 ± 3 e 13 ± 318 ± 2 f 119 ± 16 ± 1,d 12 ± 16 ± 1 24 48 1827 ± ± 2 e 2 d 12 ± 22 3 e ± 2 d 18 ± 235 f ± 1 d 6 ± 1,d 5 ± 1,d 6 ± 113 ± 1 48 72 27 14 ± 2 ± d 3 22 ± 69 2 d ± 3 35 ± 195 d ± 1 5 ± 1,d 35 ± 1 13 ± 26 1 ± 1 Rosted 72 14 ± 3 69 ± 3 95 ± 1 35 ± 1 26 ± 1 55 ± 4 Rosted 48 ± 2 61 ± 2 7 ± 1 13 ± 1 24 2 ± 3 55 ± 4 d,e 17 ± 2 48 ± 2 d,e 26 ± 1 61 ± 2 e 3 ± 1 7 ± 1 d 9 ± 1 13 ± 1 48 26 ± 2 24 2 ± 3 d 19 ± 3 d,e 17 ± 2 d,e 26 ± 1 e 7 ± 1 7 ± 1 d,e 26 ± 1 e 3 ± 1 d 9 ± 1 72 23 ± 1 d 19 ± 2 d 25 ± 1 e 6 ± 1,d 6 ± 1 48 26 ± 2 d 19 ± 3 d,e 26 ± 1 e 7 ± 1 7 ± 1 Men ± stndrd72 devition; vlues 23 ± 1 with d different 19 ± letters 2 d within25 the ± 1 sme e row differ 6 ± signifintly 1,d (p < 6.5) ± 1 s determined y Dunn s multiple rnge test (n = 3). Men ± stndrd devition; vlues with different letters within the sme row differ signifintly (p.5) s determined y Dunn s multiple rnge test (n = 3). 4. Conlusions This study revels tht the effet of soking nd rosting depends on the property studied. While soking indued derese in totl protein, solule sugr nd tnnins, nd n inrese in lipid ontent, rosting led to derese in the tnnin, phytte, nd solule protein ontents of the soyen flour. In ddition, the swelling index, gelling ility, nd visosity of the soyen flour diminished
Foods 217, 6, 12 9 of 1 4. Conlusions This study revels tht the effet of soking nd rosting depends on the property studied. While soking indued derese in totl protein, solule sugr nd tnnins, nd n inrese in lipid ontent, rosting led to derese in the tnnin, phytte, nd solule protein ontents of the soyen flour. In ddition, the swelling index, gelling ility, nd visosity of the soyen flour diminished onsiderly with soking nd rosting, while the ility to ind nd retin wter only deresed with rosting. The redutions in these properties re more importnt when soking is oupled with rosting. This study highlights the positive effet of endogenous tehnologies on the improvement of energy density of soy en flour slurry. However, the nutritionl nd sensory properties nd the miroiologil qulity of the foods mde from soked rosted soyen flour need to e investigted. Aknowledgments: We would like to thnk the Ministry of Higher Edution of Cmeroon whih, y the Presidentil Deree Ref 29/121 of 8 April 29, wrded Speil Finnil Fund to Modernize reserh in Stte Universities. We lso thnk M. Agwnnde for lnguge editing of the mnusript. Author Contriutions: A.S.N.A. olleted the mteril nd rried out the experiments. N.Y.N. designed, nlyzed the dt nd drft the mnusript. C.M.F.M. ontriuted to pper writing. All the others hve red nd pproved the mnusript. Conflits of Interest: The uthors delre no onflit of interest Referenes 1. Lee, G.-J.; Wu, X.; Shnnon, G.J.; Sleper, A.D.; Nguyen, T.H. Soyen, Chpter 1 in Genome Mpping nd Moleulr Breeding in Plnts; Oilseeds Kole, C., Ed.; Springer: Berlin/Heidelerg, Germny, 27; Volume 2, pp. 1 53. 2. Knight, D.C.; Eden, J.A. A review of the linil effets of phytoestrogens. Os. Gyneol. 1996, 87, 897 94. 3. Ekor, M.; Emerole, O.G.; Fromi, O.E. Phenoli extrt of soyen (Glyine mx) ttenutes ispltin-indued nephrotoxiity in rts. Food Chem. Toxiol. 21, 48, 15 112. [CrossRef] [PuMed] 4. United Sttes Deprtment of Agriulture (USDA). World Agriulturl Prodution; Foreign Agriulturl Servie Cirulr Series; Wshington, DC, USA, 216; pp. 6 16. 5. Plhr, W.A.; Nti, C.A.; Annn, N.T. Effet of soy-fortifition method on the fermenttion hrteristis nd nutritionl qulity of fermented mize mel. Plnt Food Hum. Nutr. 1997, 51, 365 38. [CrossRef] 6. Thngo Thngo, J. The nutritive qulity of mize-soyen (7:3) tempe flour. Plnt Food Hum. Nutr. 1995, 47, 319 326. [CrossRef] 7. Aukr, M.U.; Sopde, A.P.; Yelmi, M.B. Flow ehvior of kmu from different mize vrieties nd fortified with soyen flour. Food Control 1997, 8, 15 111. [CrossRef] 8. Akuor, P.I.; Onimwo, A.I. Funtionl properties nd performne of soyen nd mize flour lends in ookies. Plnt Food Hum. Nutr. 23, 58, 1 12. [CrossRef] 9. Egounlety, M.; Syrief, R. Study on the supplementtion of ogi with tempe. Nigerin Food J. 1992, 1, 92 12. 1. Ydv, S.; Khetrpul, N. Indigenous en fermenttion: Effet on some ntinutrients nd in vitro digestiility of strh nd protein. Food Chem. 1994, 5, 43 46. [CrossRef] 11. Bik, B.-K.; Hn, H.I. Cooking, Rosting, nd Fermenttion of Chikpes, Lentils, Pes, nd Soyens for Fortifition of Levened Bred. Cerel Chem. 212, 89, 269 275. [CrossRef] 12. Son, S.-J.; Lee, S.-P. Physiohemil nd Funtionl Properties of Rosted Soyen Flour, Brley, nd Crrot Juie Mixture Fermented y Solid-stte Fermenttion Using Billus sutilis HA. Food Si. Biotehnol. 211, 2, 159 1515. [CrossRef] 13. Shin, D.-J.; Kim, W.; Kim, Y. Physiohemil nd sensory properties of soy red mde with germinted, stemed, nd rosted soy flour. Food Chem. 213, 141, 517 523. [CrossRef] [PuMed] 14. Agume, N.A.S.; Njintng, Y.N.; Mofung, C.M.F. Physiohemil nd psting properties of mize flour s funtion of the intertive effet of nturl-fermenttion nd rosting. Food Mes. 216. [CrossRef] 15. Assoition of Offiil Anlytil Chemists (AOAC). Interntionl Offiil Methods of Anlysis; AOAC: Arlington, VA, USA, 1998; Volume 1 2. 16. Amerin Assoition of Cerel Chemists (AACC). Approved Methods of the AACC, 1th ed.; The Assoition: St. Pul, MN, USA, 2.
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