Studies On Harmful Substances In Some Foods:
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Abd El-mohsen Mahmoud Mahmoud Nezam El-din |
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Ph.D
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Benha University
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1988
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Foods.
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SUMMARYTannins affect food taste and qUality, inhibit digestiveenzymes, bind protein and lead to decrease nut~i~-tional varue of foodo This research was carried out tostudy tannins in broad beans, dates (Samani, Zaghloul,and Siwi varietie$)and tea (Ceylon and Indian). The studyincluded some treatments to bind o~ remove t~ins fromtae materials used. This study included the followingpoints:10 The a.e’CeL·mination of moisture, sugars,protein andamino aeids content in the used materials and thei.rtreatments,2-, ~he determination of phenols and tannins using fivemetnods.30 Fractionation anQ ~dentification of tannins andquantitative determination of separated tannins.4. Inhibition effect of tannin fractions on trypsin,’pepSin and amylase enzymes.50 Dece.cmfnata on of antimicrobial activity of tannini’ractions on ll)scherichia C.?li, Bac111usj’ycoid ,Sarcina Lutia, Nocardia!E, .§~ecbaromy~es_ ce~ev1siaeand Aspergi~~ua niger.Tae obtained results §WJlDlarized”as’follo.ws£’: ~~.’..:’:~”l~ Steeping bro~d bean for 16 hrs led- to increase in’the moisture content also baking process increased ~the moisture conten-c also baking process increasedthe moistu.re content in broad beans, while addingmilk powdcz- to the baked broad beans (BBB) reducedit. ’.~.~.Treated dates had; moisture content moBe than.’the fresh dates. Ceylon tea contained moisture(6.91%) slightly higher than Indian tea (6.6?%)~20 Bread bean~ contained manitol glucose, fruc.tose sucrose and oJ: marcose and raffinoseo The steepi.D.gpz-ocee.alead ~o increase the concentration o~ sugars from ’.’ana 00116 for manuit;al, glucose, sucrase and or•..~. maltose and raffioose respectively. ~ose apperedai’C€j’ steeping :for 8 and 16 hr-s , The baking processcauseci ~he decrease of glucose, fructose and sucroseand! or mal to se and disappear of mannose._ill studied dates varieties contained lJlB.Ditol.Slucose) fructose, sucrose and/or maltose While raffinosewas fOWld in IISiwin dates. SOakiI:J.iof dates led~o increase glucose from 44.085 to 49.98% and decreasedslightly raffinose and sucrose and/or maltose.Indian ana Ceylen tea contained manitol, glucose,sucrose ~d/or maltose and raffinose with concentrationof 0.060, 2.102, 0.330 and 0.042% for Indian tea and0.080, 1.946, 0.423 and 0.035% for Ceylen tea respectively.Fructese was found in Indian tea but mannose(0.098) and trihalose (0.008%) were only found in ,Oey.Lcn ”tea •.5D Brxad beans had. 23D321% Protein which decroased to··.·r’·22.81 allQ 22.660 by steeping for 8 and 19 hrs~respectively, also decreased to 22.500%.by bakingprocoss but increased by adding 2% milk powder to23.1000 St~eping and baking procoss increased someamino acids and r-educed othar amine acids, Theadaac Lon or milk powder didnot increase all maino acids •.IISamanylt, ”Zagh.Loul,” and ”8iwin dates had}0810, 4.300 and j.336% protein contents whichdacr~ased to a.?OO, 4.077 and 3.115% by seaking ~neda.ces in. boiling water for two min. The soaking r....’trea”ClC.e!1{;S did.mo,t reduce all amino acids but few~ino acids had increased or appeared~Indian and ceylon tea contained 20.000 and 19.099%pro{;ein respectivelyo4. Falin-Denis (FD) and prussian blue methods wereused for determination of total phenols, prussian .blue arid tam1in~rotein precipitation methods fortotal tannin aeterillination, l,2~diphenol, FD, vanil~lin-del and prussi’Qn bLue inethods for non-tanninphenol determination, and 1,2-diphenol, FD, vanillin-HOl and weight me~hods for determination of lowanu aiga molecutar weight tannins. The results of~revious methods indicated ~hat:Q.o B~oad. beans.ill phenols decreased, generally by steepingfor 8 and 16 hrs but total tannins increased fromO.~22 to 0.470 by steeping for a hrSD «henc..s”ternnedby prussian blue methods ,also HilI1WTincreased by steeping for 16 hrs from 0.034 and0.05.2 .co 0.040 and 0.064 when determined by’FDraYJ.Q varll.lin-HCL methods respectively!The LMWT increased in baked broad beans (BBB)to 0.215% when compared with BB by using FD methodwnile F.MWT and non-tannin phenols decreased to0.560 and 0.076%. respectively. The addition ofmilk powder to BBB led to decrease of all phenols.Tha anthocyanidin of BB decreased from 0.366 to0 ..5.50 and 0.30’::>% by steeping for 8 a.n~.16 hrs ,.” :. respectively and increased by baking of broadbean seeds to 0.4-30%. The addition ~.fmilk powderimproved ”the quality by decreasing th~”anthocy- .: ~-I.auidin and total phenols to 0.360 and· 0.54-5% when.bo Date fru.itsTotal phenOls, total tannins and LYWT decreasedby boiling in water, while non-tannin phenols,HdWT and anthocyanidin increased. Total phenolsdecreased from 10686, 1.925 and 1.900 to 1.425,1.699 and 10707, and LMWT decre~ed from 0.110.0.197 and 00311 to 00012, 0.070 and 00105% for”” •. • II I •Sanam., ?aghloll1 and Siwi. fresh and treated datesrespectively when determined by FD metnod. also~o~al tannins decreased from 0.400, 10100 and0.670% to 0.306, 0.697 and 0.~9% for Ssman1.Zaghloul aud Siwi fresh and treated dates, respe~-Lively when determined by prussian blue metho~.The .non-tannin phenols inereased from 1~166tlo56 Q.L.d 1,,295 to 1.201, 10590 and 1.’89 :for freshand treated dates of Samani, Zagh10ul and Siwivarieties, respectively when determined by FD method,~lso ~WT increased from 00023, 00069 and 0.030 to0.053, 0.095 and 0.051% for the same previousorder, respectively when determined by FD meth0C!:e.,.The statistical analysis revealed ~hat there isno~ significant difference between FD and prussianblue methods in determination of total phenols,olso there is not significant difference betweendates var~eties before and af~er treatment. Totalcannins had high significant difference when~dt~r~ned by prussian blue and tannin-proteinprecio.itation methods..’There is significant difference betweenpr-used an blue and any of other methods when detertiningnon-tannin phenols. There is not any-signifyicant a.ifference between the different varietiesof da~es w~d ~he1r treatments~·In the case of LMWT, there is not any significantd.ifference between the different· methods used.F vest indicated high significant difference~ong the differeAt date varieties and their treat-illents. LoS.D. test indicated that Siwi dates hashighest value of LMWT and there is high significant.~ • r . difference between 8iwi dates and each. of Zaghlouland Bamani dates~S~atistical analysis revealed that the traateddates has significant decrease in ~t ThU ~mean;.~nat soaking da~es in bOiling water for 2 min lead.to reduce the ~VT which in turn im~rove the tasteof the datie s, Also Siwi dates has the highestaverage o.r H.riWT content and soa.k.iJlg ..Jn boilingwa~er had not significant effect on·HMWTCo TeaThere was not significant difference in totalph~nols between Indian and Ceylon tea andolsobetween pz-uss.i.an blue and FD methods. Total tanninsdid not indicate significant difference between ttne two varieties or between the used methods.TU0re was high significant difference between allthe used methods except the difference between 1,2-uiper-d and PD. methods which was signi~icant.Ceylon tea contained higher concentration ofLmWT.than Indian teawith significant d~~ree. Sothe 4S~ringent taste which is related ·to LMWT ishi6her in ceylon tea than lndian teao .There was .’nov significant dif’.fe~ence between the used methodsor bet~’weenthe vareties of teao”An thocyanidin results indicated ~hat.the cooaent-J:’atiou ot: flavan coapounds in Indian tea is JaiP,erthan in ceylon teao The addition of milk powderto ”teabeverage led to decrease all phenol fractions(non-tannin phenols, LMWT, and BMWT)~5. By soJ?a.rationof tannins in broad beans ·’”(BB) on paperchroilla~ograpay, it qas fOQnd that: of •• ~a. Broad beans··.·r·By increasing steeping time of BB~ the m~~er~ • > •OI separated spots decreased and the baking processdecr-eased the number of separated spots from 19 tp 80Hl’viWTThe BE contained 21 spots, BBS 8 contained 13S?ots, BBS 16 contained 11, BBB contained 26 and~ffiBB contained 1? spotSD”b. Date fruitsLMwTof .Samar.l.idates were separated to 8 spots,of Za6h1ou1 dates were separated to 8 s,ilots and ofS i.wi dates were spar-aced to ? spots.By treating dates they were sepa~ted to 3., ,&~~ 3 spots for tr~~ted samani, Zaghloul and S~wi.repectively.H1lliT of aamani, Zaghloul and Siwi dates wereS~yorated to 10,8 and 19 spots and decreased byt~oating to 7,6 and 8 spots respectively.ell TeaLIi:h’lT of Indian ’teawere separated to 12 spotsand C~y1on tea were Separated to 12 spots. HMW~of Indian and Ceylon tea were separated to 12 and11 spo~s resp~ctive1y.60 Inhibi~i~n of enzymes by tanninsao The ~rypsin enzyme was inhibited by LMWT of allL::=”::0.::::i als VI;:’th different percentages. The’ steepingai BE and addition of milk powder to BBB led toUVC4’Case the inhibition .;tfect o:fta.n.nin OD. ~a.6 ..~~sted enzymes. Also in the dates treated with”boiling water, the inhibi~n eff~ct or LUWT •rne trypsin enzyJII-’!,as inhibitAd by LilrlWT ot ceylonthan Indian tea.ffiJf.~Tof steepi~ broad bean see da had inhibittnneffect on ”ChA enzynu~ leSS than BB, but the addi tian0:: mi.Lk powder ltUl . to increasA this i.nb.lbi t:1.oneffecl;.3A~T o~ aate fruits have. Inhibiton etreet on~he enzyme and this inhibition was decreased by~reating the dates with boiling water. Also, HYW~of the two tea varieties had innibition effect on”Ch~ -c’-yp.ti:in enzyme.o , Pep s Ln enz ymaLMWT of steeping BBS had higher inhibition effect” ” on pepsin enzyme. also the baking process revealedinhibition effect on the enzyme but the addit.ion ofllIilk powder reduced the inhibition effect •LMWT of date frQits had some inhibition effecton pepsin enzyme except LMWT of Siwi dateso AlsoIndian and Ceylon tea had high effect on tha~nzJme inhibi~ion •HMWT of BBB 16 had inhibition effect (82.00%)Les s than BB (100%) and BBS 8 (100%): ~ By processingBB to produce BBB its HMWT had less inhib1tion~ff~ct (64.90%) than BB also MBBB decreased theinhibition of enzyme to 62000%”H~WT of treated dates had ~~ibi~iou e£fect onenzJ~e less tcan the fresh dates! Also ~ of~ey10n~~a had high inhibition effect (100%) than- IfF -I~dian tea. (60.00%) 0Co oe-Aillylaseenzymeste,;;pj.ugbJ:cad beaas led’ to decrease in theiru~ibi~ion effect of &-amylase. Baking of BB increasedthe inhibition of ~amylcse but When milkpowder was add~d the inhibition effect 9£ ~-amyl~ase e~3J~e decreasedQ:u.iWT of the treated dates had less’; inhibitioneffect than that of fresh dates, on the enzymeoUiWTof’ Indian and Ceylon tea had ·the maximumillilibition on ~-amylase enzyme!EW~VT of BBS 8 and BBB 16 ~ed to decrease theinhibition from 97% of BE to 71.66 and 66% respectivelYtalso the addition of mil~ powder. to BBBl;d to decrease the inhibition of ~amylQseenzyze from 97000 to 95.00% 0.fuiJ.WT of’dates head to deorease in.the inhibitioneffect of ~-amylase by treating from 40 and 27.% to10% for eaca of Zaghloul and •Siwi ’dated. while in’Samani’ dates the inhibition increas~d f~om 11 to20%••HMWT in Indian teachad inhibition effect (54%)~ore ~han in Ceylon tea (190370%)70 By s~Qding the difect of tannin fractions-on someillicr~o~banisms(~•c•herichia coli, Bacillu,..:s mycoid, JSa.r:’cinaIlltia;Nocardia sp!, saccharom.yces cere171s-iaf”’;0ana Asoergillu~ ni~er)o ,It was found that:LMWT of BB had antimicrobial effect on Eo c-oli~~~ S-.,..lu~ti.a-.- only.. LMWT of BBS 8 had inhibit on effecton tine growth of B. mycoid, S.,! 1utia_, and Sac,_cere~iae , bQ~ the steeping for 16 hra prevented theinhibition effect and only So lutia was inhibited,BBBhad inhibition effects 011 E.coli and BomycoidoThe add.i,tion of milk pa.der to BBB Led to lowLnh.Lb L1;wn effect on Eo mycoid and ~_ lU1iia..~’VT of BB had inhibition effect on A. II!Ycoid andBB2 (3 had lc’,’! iuhibit:l.on o:ffec-t on l!.:-- !DYcoid andS•• lQt~§. out the sueepang for 16 hours prevented allinnioi tion effdcts. Two organisms (~~:·,-mycoid and !.!nig;er) were i~ibi ted by HMWT of BBB rFoul Medammes)but the addi~ion of milk powder (MBBB) led to removetile inhibi tioe. effectoLil£~”T of ”Samani II· dates had low inhibition on S-ac’ocarevisiea and Ao . niger and by trealing .’Samani’ datestne inhibition was found with -Eo-co-li, Nocardia s-P. andit.. niger ..LJitiWT of ”Zagh.Loul,” dates had low inhibition effecton Sac. cerevisiae .., this effect didnot change by treatingDoiling watero LMWTof ”Siwi” dates had inhibitioner rec c on Sac •• cerrviaiae’ and A. niger and by treatingE. coli and Sac. carlVisiae. were inhibited.HM~ of ’Samani’ dates had ligh inhibition ~fecton 40 niger but by treating the dates.no inhibi tn’.oncccur-ad;F~WT of Zaghloul dates had low inhibition effecton A••uie;aT. and by treating E.~. :!!niger was inhibited’-;;,yffilIWT of • Siwi’ dates and by boili.,og in waterfOl’ 2. lllin. tc.Ls inb.ibi tn on was removed b.llt E~.col.i -wasin”nibi ted.LMWT of Indian tea had aigh inhibition effect onE~coli and So lutia but its HMWT had the inhibition&ffec~ on -Eo’-coli only,LUWT of Ceylon tea had inhibiton effect on ~~”. S.lu.lia SJ.1.d Nocaria ~. t While HMWTinhibitedTn.e ,;>henoliccompounds had inhibition effect ondifi’e.r:’ent (nicroorgonisms depending on the phenoiCO~D.pound.s~It may be ”concluded that for binding or removingvannins ~he follOWing treatments may be recommended:Broad bean should be steeped bafor baking and prpteinsource may be added to the broad beant( Foul Medammes ).Da.-t;es containing ~igh It:vel of tannins in matillr@s~ag0 (~~alal stage) such as ’Siwi’ variety and toreaQce the as~ringent ~aste Dates may b’ treated by~~~)ing in boiling water for two minutesoTea had. high tannin con:teuj; ~ and the addi tien ofmi.Lk)revent nne effect of tanaino |
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