Effect of Bio Preservation as a Modern Technology on Quality Aspects and Microbial Safety of Minced Beef

Transcription

1 Glol Journl of Biotechnology & Biochemiry 7 (2): 38-49, 2012 SSN X DOS Pulictions, 2012 DO: /idosi.gj Effect of Bio Preservtion s Modern Technology on Qulity Aspects Microil Sfety of Minced Beef Rehm A. Amin Deprtment of Food Control, Fc. Vet. Med. Benh University, Egypt Arct: The effect of nisin Lctocillus cidophilus iividully in comintion on sensory (color, odor consiency), chemicl (ph, totl voltile sic nitrogen "TVB-N" iorituric cid "TBA") cteriologicl (totl colony count "TCC", Enteroctericee count coliform count) qulity ttriutes of fresh minced eef, s well s on e grow survivl of Stphylococcus ureus, s food orne pogenic cteri, experimentlly inoculted into fresh minced eef, ws udied during chilling orge t 4 C. Sensory nlysis iicted significnt vrinces in using nisin e comintion tril. The results showed t e pplied tretments mrkedly decresed ph, TVB-N TBA vlues s well s TCC, Enteroctericee count coliform count, s compred wi e control smples roughout chilling orge, when used seprtely, ut e preservtive ctivity highly incresed wi e comintion tril. n ddition, highly significnt differences (P<0.05) etween e different tretments were noticed. Shelf life of smples treted wi nisin, Lctocillus cidophilus comintion tril, Lctocillus cidophilus nisin incresed reched over 6, 3 5 dys of orge t 4 C, respectively, compred to t of control smples which reched 2 dys only. nitil count of S. ureus in minced met smples ws 8.54 log CFU/g, which decresed following tretment directly wi nisin y 1.21 log CFU/g (14.17%), 2.54 log CFU/g (29.74%) rd 3.69 log CFU/g (43.21%) in e 1 dy, 2 dy 3 dy, respectively, while fter tretment wi Lctocillus cidophilus y 1.54 log CFU/g (18.03%) 4.87 log CFU/g (57.03%) in e 1 dy 2 dy, respectively finlly fter tretment wi e comintion of o y 3.87 log CFU/g (45.32%) in e 1 dy. Wheres, e grow of Stphylococcus ureus in minced met smples ws completely inhiited fter eing rd treted wi nisin, Lctocillus cidophilus comintion of o in e 4 dy, 3 dy 2 dy, respectively. The ctivity of e pplied tretments followed e following order: nisin > comintion of nisin Lctocillus cidophilus > Lctocillus cidophilus for shelf life extension, while comintion of nisin Lctocillus cidophilus > Lctocillus cidophilus > nisin, for e grow inhiition of Stphylococcus ureus. t could e concluded t e potentil of comintion of nisin Lctocillus cidophilus s proiotic to inhiit e grow of common food spoilge cteri opens up new perspectives for e io preservtion of met products. Key words: Nisin Bcteriocin Proiotic Lctocillus cidophilus Stphylococcus ureus NTRODUCTON Microil contmintion of met occurs primrily due to rw mterils, griing of met which will spred Met hs long een considered s highly desirle, exterior contmintion essentilly roughout e entire nutritious protein-rich food, ut t e sme time, muscle mss, po processing hling, crossunfortuntely, it is lso highly perishle ecuse it contmintion /or equipment, lck of refrigertion provides e nutrients needed to support e grow of fcilities, mient tempertures ove 20 C, lck of mny types of microorgnisms. Due to its unique suitle trnsporttion etween e production iologicl chemicl nture, met uergoes mrketing res improper orge temperture [2]. progressive deteriortion from e time of slughter until The microiologicl spoilge of foods is due to e consumption [1]. iochemicl ctivity of microorgnisms s ey grow in Correspoing Auor: Rehm Ad El-Aziz Amin, Deprtment of Food Control, Fc. Vet. Med., Benh University, Egypt. Tel:

2 Glol J. Biotech. & Biochem., 7 (2): 38-49, 2012 food, cusing chnges in e food s ppernce, odor, cultures / or eir nticteril metolites texture, or te. Since food orne pogens do not (cteriocins) to inhiit or deroy uesirle typiclly give n orgnoleptic iiction of eir microorgnisms in foods, improve microiologicl sfety presence, e orgnoleptic chnges cused y spoilge exte e shelf life of foods [12]. microorgnism serve s wrning to e consumer LAB hve gret potentil for use in io preservtion t e food could e unsfe for consumption, us, ecuse of eir generlly regrded s sfe "GRAS" protecting millions of people from food orne illness tus. LAB re widely used in food iury s rter [3]. Stphylococcus ureus is generlly regrded s cultures, co-cultures, or io protective cultures in wide food orne pogen cusing spoilge rnge of fermented foods since ncient times wiout ny intoxiction due to e production of het le sfety risk [13]. n ddition to e food pplictions of enterotoxins [4]. LAB, vrious rins re considered to e protective Food preservtion is continuous fight which ims cultures. Functionl protective cultures re t eier to eliminte or reduce e outgrow potentil of microorgnisms t possess t le one inherent spoilge pogenic microorgnisms in foods. Until functionl property, which cn contriute to improvement now, pproches to seek improved food sfety hve relied in sensory ttriutes in terms of consumer cceptnce on chemicl preservtives, ntiiotics or on e rough production of flvor rom compous, food ppliction of more dric physicl tretments (e.g. high sfety rough competing wi food spoilge tempertures or refrigertion). Nevereless, ese pogenic microflor improving e nutritionl meods hve mny drwcks [5]. Currently, ere is qulities erey extension of shelf life of foods [14]. rong dete out e sfety spects of chemicl LAB wi hel-promoting properties, re clled preservtives due to impirment/reduction of e proiotic rins. Thus, LAB fermenttion is not only of nutritionl vlue of food, episodes of dverse food mjor economic importnce, ut it lso promotes humn rections, crdio-vsculr disese, mny crcinogenic hel [15]. Lctocillus cidophilus is one of e mo tertogenic ttriutes s well s residul toxicity [6]. common species of LAB which hve een used mo Processing t high tempertures extensively dmges e commonly s proiotics dded s functionl orgnoleptic, nutritionl physicochemicl properties components to vrious food products, primrily ecuse of food [7]. Refrigertors re eier expensive to mintin ey re e predominnt lctocillus in e inteinl or mens for eir mintennce (electricity) re lcking trct of hely humns, preventive effect gin is meod of preservtion mkes e met product prone ntiiotic-ssocited dirrhe [16] eir erpeutic to microil oer sources of contmintion [8]. ctivities ssocited wi n inteinl microil lnce Nowdys, for ese resons, especilly s [17]. consequence of consumer diru of chemicl Bcteriocins re ctionic, hydrophoic or preservtives, consumers py lot of ttention to e mphiphilic, riosomlly synesized, extrcellulrly reltion etween food hel [9]. relesed, primry or modified ioctive peptides or Firly, consumers dem high qulity, dditive- peptide complexes secreted y Grm positive s well s free, sfe, hely, nutritious, vitmin-rich, minimlly Grm negtive cteri, wi ctericidl or processed, fresh ting, lightly preserved functionl cteriotic effect gin oer closely non-closely foods wi exteed shelf life nturl or "green" relted species. n ll cses, e producer cell exhiits imge experiencing e tre of Weern society of specific self immunity to e ction of its own cteriocin green consumerism [10]. Secoly, legisltion hs [18]. Nisin is e only one interntionlly ccepted s rericted e use s well s e permitted levels of some sfe nturl food io preservtive in certin foods for of e currently pproved preservtives in different foods. severl decdes [19]. Nisin is rod spectrum These consumer legisltive needs hve encourged cteriocin wi ctericidl ctivity, even in very low e food iury to fi innovtive pproches of food concentrtions, towrds wide rnge of Grm-positive preservtion [11]. cteri, including S. ureus L. monocytogenes [9], Recently, novel scientific pproch t hs een decresing e risk for eir trnsmission rough e food widely employed in e food iury gining more chin. Nisin is extremely resint to het. t is solule in more ttention is e io preservtion technology. By dilute cids le to oiling in such solutions. t is definition, is concept refers to e use of non not toxic, even t levels much higher n ose used in pogenic ntgoniic microorgnisms s protective foods. 39

3 Glol J. Biotech. & Biochem., 7 (2): 38-49, 2012 Alough gret del of work hs een done on e met surfces [24]. Susequently, e inoculted mets selection of cteri exhiiting ntimicroil properties in were kept for 20 min to llow ttchment sorption liquid medium e numer of cteriocins of cteri, wi e initil count mde 2 hrs fter chrcterized is incresing every dy, very few commercil inocultion (fter 2 hrs = Zero dy) [25]. pplictions hve ppered in met products. A mjor hurdle is t ese products re not fermented e Collection Preprtion of Smples: A gr totl of selected LAB rin should not chnge eir orgnoleptic 6 kg of fresh minced eef ws collected from different nutritionl qulities. However, ere hve een very, utchers shops in Tnt, Ghri governorte, Egypt. few conclusive ttempts to control e spoilge The smples were tken trnsferred directly to e microiot wi protective culture [20]. lortory using n ice ox uer complete septic coitions wiout uue dely. All e smples were n Reltion to Aove, e Min Trget of is Work Ws immeditely prepred, inoculted wi S. ureus to Evlute e Following: 6 (10 CFU/g) [22] en divided into four equl groups (1.5 Kg ech). The control group ws wiout ny The efficcy of nisin Lctocillus cidophilus, tretment, group contined nisin, in e form of e iividully in comintion on sensory, chemicl commercil product Nisplin, in n mount of 200 ppm cteriologicl qulity spects, s well s, (ìg/g) [26]. Group ws inoculted wi Lctocillus exteing e shelf life improving e microil 7 cidophilus (10 CFU/g) [21], while group contined sfety of fresh minced eef ored t 4 C. nisin Lctocillus cidophilus in comintion. Ech The efficcy of nisin Lctocillus cidophilus smple ws pcked in polyeylene g, leled iividully in comintion on improving e ored t 4 C. Sensory (color, odor texture), chemicl microil sfety of fresh minced eef inoculted wi (ph, TVN-B TBA) cteriologicl (TCC, food orne pogenic cteri s S. ureus ored Enteroctericee count, coliform count S. ureus t 4 C. counts) nlyses were coucted initilly (fter 2 hrs = Zero dy) every dy (24 hrs) during orge. MATERALS AND METHODS Sensory Exmintion: t ws crried out ccording to Preprtion of Bcteril Strins Person Tuer [27]. Lctocillus Acidophilus: Lctocillus cidophilus ws kily supplied s reference proiotic rin from Microiologicl Resources Center (Ciro MRCEN), Chemicl Anlysis: PH: Strd nlyticl meods [28] were used to determine ph. Fculty of Agriculture, Ain Shms University, Egypt. The rin ws grown on De Mn Rogos Shrpe ro (MRS, Difco Ls. Detroit, M, USA) for 24 hrs t 30 C. From is 8 culture, dilutions up to 10 were plted on MRS gr to rech e recommeed cell count of e proiotic in food 7 (10 CFU/g) [21]. Stphylococcus Aureus: Stphylococcus ureus, otined from Microiology Deprtment, Fculty of Veterinry Medicine, Benh University, Egypt, ws cultured in erile peptone wter 0.1% (Merck, Germny) ws en incuted for 24 hrs t 37 C. From is 10 culture, dilutions up to 10 were plted on Bired prker gr to determine e cell concentrtion. The cell count 6 ws djued to 10 CFU/ml [22]. The effective dose of enterotoxin my e chieved when e popultion of S. 5 ureus reches level of > 10 CFU/g [23]. Stphylococcus ureus ws inoculted on decontminted met y pouring swing over e TVB-N: Totl voltile sic nitrogen (TVB-N) ws determined in diilltory syem (UDK 130A), s descried y Antoncopoulos Vyncke [29]. TBA: Thiorituric cid (TBA, mg mlonldehyde/kg) ssy ws crried out ccording to e procedure of Schmedes Holmer [30]. Bcteriologicl Anlysis: Bcteril counts were mde every 24 hrs using rd meods [31]. Ten (10) gm of e exmined smple were oroughly homogenized using 90 ml of erile peptone wter 0.1% (Merck, Germny) to 1 otin 10 dilution from which, oer deciml seril 7 dilutions up to 10 were prepred. Approprite medi were used for enumertion identifiction of microflor. Totl colony count (TCC) ws determined y plting pproprite dilutions on plte count gr (Difco, USA). Pltes were incuted for 48 hrs t 30 C. Totl 40

4 Glol J. Biotech. & Biochem., 7 (2): 38-49, 2012 Enteroctericee coliform counts were determined 7 exceeds out 10 orgnisms/g of food [3]. A wide vriety using Violet Red Bile Glucose (VRBG) gr Violet Red of microorgnisms including phylococci produce Bile (VRB) gr (Biokr, Frnce), respectively. The pltes lipolytic enzymes t hydrolyze lipids, producing redily were incuted for 24 hrs t 37 C. Stphylococcus ureus oxidizle surtes t hve rncid odor. Mny count ws determined on Bird prker Agr (Merck, spoilge cteri produce proteolytic enzymes t Germny). Pltes were incuted t 37 C for 48 hrs. hydrolyze proteins in foods leding to offensive odor [3]. Stphylococcus ureus showed lck shiny colonies Mo groups of microorgnisms cn spoil food y wi nrrow white mrgins surroued y cler hlo growing on e surfce. Refrigerted cured mets zone exteing into e opque medium. After e period cooked products cn ecome slimy or icky to e touch of incution, e numer of colonies ws enumerted in ecuse of e grow of LAB. This prticulr spoilge ech Petri dish. defect is cused simply y e ccumultion of very high numers of microil cells not y ny specific Sttiicl Anlysis: All experiments were coucted in metolic ctivity of e microes. Similrly, color triplicte on seprte dys e rimetic men ws chnges in food cn occur ecuse of e surfce grow reported s e finl result. The mens of cteril of microorgnisms. Exmples include e greening of popultion (CFU/ml) were converted to log 10 CFU/ml. mets, cused y LAB [3]. Sttiicl nlysis ws performed using SPSS tiicl The ph vlues of minced eef smples rnged progrm for wiows (Version 16) (SPSS nc. Chicgo, L etween 5.32± ±0.05, 5.60± ±0.09 USA). Strd devition of men ws used to 5.55± ±0.09, for groups,, descrie dt. Fisher s rnge te ws used to determine respectively, while its vlue in control smple ws 5.82 t differences (P<0.05) etween teed groups. P vlue<0.05 zero time of orge s shown in tle (2). The vlues of ws considered s significnt. ph incresed in ll tretments, especilly in control t e e of orge period. RESULTS AND DSCUSSON TVB-N content in control recorded 7.37±2.00 mg/100g smple while its content in groups, rnged from n spite of e introduction of modern technologies 6.87±2.22 to 19.52±0.58, 7.12±2.05 to 20.5±1.38 sfety concepts (e.g. HACCP) e wide rnge of 7.00±2.08 to 21.18±2.81 mg/100g smple, respectively, s rou ville preservtion techniques, e reported shown in Tle (2). During orge, control smples numer of food orne illnesses intoxictions is in rise recorded high vlue of TVB (20.35±0.17 mg/100g smple) food sfety is ill n incresingly importnt pulic in e 2 dy, while its vlue ws low in ll tretments. hel issue [32]. Tle (2) exhiits t TBA vlues rnged from 0.07± t is ovious from results otined in Tle (1) t to 0.91±0.04, 0.12±0.09 to 0.93± ±0.03 to e sensory ttriutes of different treted minced eef 0.95±0.08 mg mlonldhyde/kg smple in groups, smples during cold orge (4 C) were improved y, respectively its vlue in control smples ws using groups,, compred to e control smples 0.13±0.05 t e eginning of orge to 1.00±0.003 mg during e orge period. Generlly, smples of groups mlonldhyde/kg smple in e 2 dy of orge., respectively reveled e highe improvement of Similrly, e use of metolites produced y sensory ttriutes, while smples of group Lctocillus improved e sensory iochemicl demonrted e lowe one. n ddition, e shelf life of qulity criteri (ph, TVN & TBA) of frozen fish fillets [34], smples of groups, which reched 6, 5 3 fish-sed food products [33] srdine [35]. dys, respectively, s compred to t of control smples ph vlue plys n importnt role for e which reched 2 dys only [Fig. 1]. Nerly similr results microiologicl grow ffecting e shelf life of e were otined y Gelmn et l. [33]. products [17]. ncrese in ph vlue ws ttriuted to Spoilge chrcteriics develop in food s formtion of voltile sic nitrogen components s microorgnisms dige e sugrs, complex ffected y iochemicl chnges uer low temperture crohydrtes, proteins fts of food producing [34] to microil lod which my cuse protein uesirle effects in e food if e spoilge hydrolysis wi e ppernces of lkyl groups [36]. The microorgnisms grow to significnt levels. Typiclly, e decrese in ph in e inoculted smples ws closely reshold level for oservtion of food spoilge y odor, relted to e production of lctic cid orgnic cids te, or sight is not reched until e spoilge microflor y L. cidophilus. 41

5 Glol J. Biotech. & Biochem., 7 (2): 38-49, 2012 Tle 1: Sensory evlution of untreted (control) treted minced eef smples during cold orge t 4 C Zero dy 1 dy 2 dy rd 3 dy 4 dy 5 dy 6 dy 7 dy Control Spoiled Spoiled Spoiled Spoiled - Score Syem for Sensory Evlution [27]: 9: Excellent 4: Fir 8: Very very good 3: Poor 7: Very good 2: Very poor 6: Good 1: Very very poor 5: Medium Tle 2: Chemicl evlution of untreted (control) treted minced eef smples during cold orge t 4 C Zero dy 1 dy 2 dy rd 3 dy 4 dy 5 dy 6 dy ph Control 5.82± ± ±0.11 *** *** *** *** 5.32± ± ± ± ± ± ± ± ±0.09 *** *** *** 5.55± ± ± ± ±0.09 *** TVN Control 7.37± ± ±0.17 *** *** *** *** 6.87±2.22 c 11.53± ± ± ± ± ± ± ±1.38 *** *** *** 7.00±2.08 c 12.23± ± ± ±2.81 *** TBA Control 0.13± ± ±0.003 *** *** *** *** 0.07± ±0.05 c 0.30± ± ± ± ± ± ±0.06 *** *** *** 0.10± ± ± ± ±0.08 The vlues represent Men ± SD of ree experiments., c re significntly different (P < 0.05) TVN = 20 mg / 100 gm rw minced eef [38] TBA = 0.9 mg Melnoldehyde / kg rw minced eef [38] Tle 3: Bcteriologicl evlution of untreted (control) treted minced eef smples during cold orge t 4 C Zero dy 1 dy 2 dy rd 3 dy 4 dy 5 dy 6 dy TCC Control 9.73± ± ±2.52 *** *** *** *** 7.00± ± ± ± ± ± ± ± ±3.46 *** *** *** 8.00± ± ± ± ±1.00 *** EC Control 7.14± ± ±1.00 *** *** *** *** 5.00± ± ± ± ± ± ± ± ±1.15 *** *** *** 6.33± ± ± ± ±1.15 *** CC Control 6.72± ± ±2.31 *** *** *** *** 4.33± ± ± ± ± ± ± ± ±1.15 *** *** *** 5.67± ± ± ± ±0.58 *** TCC: Totl Colony Count EC: Enteroctericee count CC: Coliform Count The vlues represent Men ± SD of ree experiments., c re significntly different (P < 0.05) TVB-N vlue ws more useful for ssessing e degree of met deteriortion n for evluting e chnges occurring during e fir orge ges [37]. EOS [38] ted t 20 mg TVN/ 100 gm rw smples iictes e spoilge of minced met. The increse in TVB-N is generlly cused y e rekdown of proteins s result of microil ctivity uer low temperture utolytic proteolytic enzymes. Such increses in TVB-N cn e ttriuted to y e voltile sis production (NH 3, TMA, DMA hypoxnine) Fig. 1: Shelf life of untreted (control) treted minced non-voltiles (himine) ose compenory of free eef smples ftty cids resulting from lipids deteriortion [34]. 42

6 Glol J. Biotech. & Biochem., 7 (2): 38-49, 2012 TBA is good iictor of e qulity of met The reduction of coliforms numer might ensure good io products. TBA vlue is widely used iictor for e preservtion gin uesirle /or hzrdous ssessment of degree of lipid oxidtion [39]. Limit of microorgnisms [35]. cceptnce for TBA is proposed s 0.9 mg Bcteriocins produced y LAB, especilly nisin, hve Melnoldehyde / kg rw minced eef [38]. e potentil to cover very rod field of ppliction, Concerning e incresed TBA vlues for ll e including food iury s sfe nturl food preservtives ored smples wi dvncing e chilling orge [19]. Bsed on trget orgnisms, nisin is used to prevent time; it could e due to lipid hydrolysis, oxidtive spoilge y Grm positive eospore formers (prticulrly rncidity secory products formtion uer low in het processed food) LAB to kill or inhiit temperture [40]. Grm positive pogens, s well s, Grm-negtive Tle (3) clers e effect of tretment in groups, cteri, ut only when used t high concentrtions [45]. on TCC for minced eef smples during orge t The direct inocultion of e crude extrct of cteriocin 4 C. nitil TCC for control smples t zero time ws will eliminte e inconvenience of e orgnoleptic 9.73±0.87 log cfu/g en shrply incresed wi chnges [46]. dvnce orge to 11.67±2.52 log cfu/g fter 2 dys t is well recognized t e ntimicroil effect of orge. n ddition, ll tretments hd inhiitory ctivity, nisin is cused y memrne depolriztion especilly groups, respectively. permeility y pore formtion in e cytoplsmic The effect of tretments, on totl memrnes of sensitive trget species, in torrid mnner Enteroctericee counts for minced eef smples ws fter electrotic interctions wi phospholipids shown in tle (3). nitil counts of Enteroctericee negtively chrged iing to lipid. This ep is in control smples were 7.14±0.63 log cfu/g t zero time ought to e e driving force for susequent events en mrkedly incresed wi exte orge. [47]. Nisin dissiptes y incresing memrne Enteroctericee ws reduced in ll tretments permeility. Following nisin tretment, whole or intct especilly group followed y group. sensitive cells memrne vesicles exhiit efflux of Tle (3) illurtes e effect of groups, on ATP, mino cids ctions (minly potssium totl coliform counts for minced eef smples during mgnesium). Loss of ese sunces inctivtes orge t 4 C. nitil coliform count for control minced sulfhydryl groups depletes proton motive force, eef smples t zero time ws 6.72±0.34 en highly which ultimtely interferes wi cellulr iosynesis of incresed wi dvnce orge to rech 7.33±2.31 log DNA, RNA, protein polyscchrides, s well s, e cfu/g fter 2 dys of orge. n ddition, groups, production of energy. These events result in collpse of respectively, roughout orge period hd more e memrne potentil ultimtely cuse cellulr de inhiitory ctivity on totl coliform counts n oers. utolysin ctivtion to dige e cellulr wll [6]. Group ws reltively less ctive. L. plntrum L. lctis hve showed more The ddition of nisin inhiits e microil grow in cteriocin producing ility compred to L. cidophilus fresh vel met [41], met products [42] smoked [48]. Bcteriocins re not frequently ctive gin slmon [43]. Similrly, e use of metolites produced y Grm-negtive cteri. The lipopolyscchride of e Lctocillus improved e microil spects (TCC, SAC outer memrne of is clss of cteri cts s CC) sfety of frozen fish fillets [34], fish-sed permeility rrier for e cell. t is responsile for food products [33] srdine [35]. preventing molecules from reching e cytoplsmic The reltively high initil counts of control smples memrne [49]. my e ttriuted to e griing process, which n some innces, LAB my cuse food spoilge compous e prolem y introducing e pogens since eir enzymes my led to genertion of into e interior of e met contriutes to e fermenttion diges which re responsile for rong increse of totl vile counts of met [44]. sensory degrdtion, leding to rejection of e products. The numers of Enteroctericee were higher in The crohydrtes fermenttion y heterofermenttive control smples n in treted smples. The grow of LAB leds to sour mrinted off-odors flvors Enteroctericee might hve een reduced s result due to orgnic cid production. Degrdtion of proteins of ntimicroil ctivity of e LAB nisin. The y is genus my lso coucts to itter te. Cyeine reduction of coliform counts in treted minced eef rginine cn e metolized into H S NH smples could e due to e cidifiction y lctic cid respectively, responsile for sulphurous mmoni off/or to some inhiitory compous formed y LAB. odors [20]

7 Glol J. Biotech. & Biochem., 7 (2): 38-49, 2012 Tle 4: The effects of different preservtives on Stphylococcus ureus counts (log CFU/g) in rtificilly inoculted minced eef smples rd Zero dy 1 dy 2 dy 3 dy 4 dy 5 dy 6 dy Control 8.54 ± ± ± ± ± ± 1.38 ND ND ND 7.00 ± ± 0.58 ND ND ND ND c 4.67 ± 0.58 ND ND ND ND ND ND: Not Detected The vlues represent Men ± SD of ree experiments., c re significntly different (P < 0.05). Tle 5: Reduction log % of Stphylococcus ureus rtificilly inoculted into minced eef smples treted wi different preservtives 1 dy 2 dy rd 3 dy 4 dy 5 dy 6 dy Log % Log % Log % Log % Log % Log % Even so, severl uors reported t certin cteriocin-producing LAB could e used s io protective cultures seemed to e more efficient n cteriocin to prevent e grow of food orne pogens such s S. ureus in susge [53], eef urger [54] mny forms of met products [55-57]. Results re in synchroniztion wi ose reported y Hmpikyn [26], Clevel et l. [58] González- Mrtínez et l. [59] who ted t ll of e vrints of Fig. 2: Reduction % of Stphylococcus ureus rtificilly nisin inhiit food orne pogens including S. ureus. inoculted into minced eef smples The inhiition of grow of S. ureus could e due to e nticteril metolites of LAB such s orgnic cids Tle (4) showed S. ureus counts in minced eef (which led to rpid reduction of ph elow 5.3), H2O2 smples treted wi groups,. The initil count (where S. ureus is 2 to 10 times more sensitive to H2O2 of S. ureus in minced eef smples fter inocultion ws n mo LAB), cteriocins (which re more effective 8.54±0.34 log CFU/g. Stphylococcus ureus counts in gin Grm positive cteri n Grm negtive minced eef smples treted wi groups, in e cteri) cteriocin-like sunces [60]. 1 2 dy of orge were significntly lower The sfety of fermented product primrily depes (p < 0.05). Moreover, e grow of S. ureus in minced on rpid decrese in ph, which mu e chieved s eef smples ws completely inhiited fter tretment wi quickly s possile in order to inhiit e grow of rd groups, in e 4, 3 2 dy of orge, spoilge microorgnisms in e finl product [61]. respectively. Stphylococcus ureus counts in treted n mmmlin met, e glycogen content is higher minced eef smples declined from 8.54±0.34 to 7.33±0.58 n in fish, leding to po rigor cidifiction (ph<5.5) log cfu/g (14.17%), 8.54±0.34 to 7.00±2.00 log cfu/g t prevents grow of e ph-sensitive cteri (18.03%) 8.54±0.34 to 4.67±0.58 cfu/g (45.32%), when llows e implnttion of LAB [20]. treted wi groups,, respectively, in e 1 dy Bcteriocins (such s Clss cidocin CH5 produced of orge (Tle 5 & Fig. 2). The results iicted t S. y L. cidophilus) hve generlly ctionic chrcter ureus ws reduced in ll tretments especilly group esily interct wi Grm-positive cteri t hve followed y group en group. high content of nionic lipids in e memrne Similrly, e comintion of lctic cid cultures determining e formtion of pores [62]. eir cell-free cteriocins hs iuced greter inhiitory There re, however, some common mechnisms of effect on different spoilge pogenic microflor ction t hve een reported for e mjority of LAB. n e use of single cteriocin, on fresh met [50] LAB exert rong ntgoniic effect gin food mny forms of met products [12, 51, 52]. spoilge pogenic microorgnisms y competitive 44

8 Glol J. Biotech. & Biochem., 7 (2): 38-49, 2012 exclusion for essentil nutrients or dhesion sites of developed ese cells ecme nisin-sensitive. mucous cells, immune modultion, redox modifiction, The ntimicroil effectiveness of nisin rongly depes ccumultion of D-mino-cids production of on its mode of delivery. Resince my result proly extrcellulr diffusile ntimicroil metolites, such from ltertion of cteril memrne composition, s orgnic cids (lctic, propionic, formic cetic deruction of e cteriocin y proteses or ltered cids), dicetyl, hydrogen peroxide, cron dioxide, receptors. ntifungl compous (ftty cids or phenyl lctic cid), The effectiveness of nisin ctivity s preservtive in lysozymes, enzymes (proteses, mylses lipses) food is negtively ffected y: (1) its hydrophoic nture, cteriocins, which ply n essentil role in nturl lough ey re reltively smll molecules so ey preservtion, enhncing e sfety exteing e cn esily diffuse into e wter phse of food products, shelf life of food products [63]. (2) its mphiphilic nture, it cn e dsored to food Lctic cid, secreted y is proiotic s e primry mcromolecules uergo proteolytic degrdtion y metolite of crohydrte fermenttion, lowers ph of e proteses oer proteolytic enzymes relesed during food directly inhiits e grow of pogenic cell lysis, especilly in non het-treted foods, e cteri. Furermore, uissocited lctic cid, on pprent higher proteolytic ctivity in homogentes cn ccount of its ft soluility, will diffuse into e cteril e explined y e proteses eing intrcellulr cell memrnes, erey lowering e intrcellulr ph relesed during homogeniztion of e met. n whole interfering wi metolic processes such s oxidtive met, ere will e less contct etween e nisin e phosphoryltion [64]. Cron dioxide intercts wi cell proteses. (3) e physicochemicl chrcteriics of food memrnes y reducing internl externl ph levels such s nutrients, temperture ph which ffects e plys role in creting n neroic environment grow rte of trget microorgnisms chnges e which inhiits enzymtic decroxyltions e degree of ioniztion (dissocition / ssocition) of e ccumultion of CO 2 in e memrne lipid ilyer my mo ctive chemicls could chnge e ntimicroil cuse dysfunction in permeility. Dicetyl, n rom ctivity, (4) leching into e food cross-rections flvor component, is product of citrte metolism wi food components such s lipids or proteins, (5) e cts y intercting wi rginine-iing proteins poor soluility lck of ility t e ph of rw met [65]. Hydrogen peroxide is powerful oxidizing ph (neutrl high ph vlues), (6) uneven diriution ntimicroil gent which oxidizes sulfhydryl groups in e food mtrix due to rong interction wi deroys cteril enzymtic ctivity deroys cteril phospholipids, (7) sensitivity to food enzymes, (8) enzymtic ctivity form e peroxidtion of memrne inctivtion y formtion of nisin glutione dduct, (9) lipids cell proteins us incresing memrne nisin molecule numer implicted in pore formtion my permeility. Hydrogen peroxide my lso e precursor e lower to kill cells, (10) development of highly tolernt for e production of ctericidl free rdicls such s /or resint rins to nisin, (11) iequte superoxide (O 2 - ) hydroxyl (OH ) rdicls which cn environmentl coitions for e iologicl ctivity dmge DNA [66]. Enzymes hydrolyze food complexes (12) eir inhiition y slt curing gents [69]. (polyscchrides, proteins, phyttes lipids) into No single ntimicroil gent cn cover ll e simple non toxic products wi desirle textures, rom requirements for food preservtion [70]. The ppliction t mkes em pltle for consumption [67]. of comined preservtive fctors (nisin L. The nticteril effects of proiotic (LAB) gin cidophilus) is significntly greter in controlling e common food orne pogens depe on e type of grow of food spoilge food orne pogenic product used, species of pogenic cteri, interction cteri n t of single cteriocin used lone [71]. etween e cteri, its dpttion to surte, Similrly, lctic cid, secreted y L. cidophilus, e cid production, e microorgnism sensitivity, NCl, lowers ph of e food. Nisin hs n immedite phredox potentil (Eh), wter ctivity ( w), ph, orge depeent ctericidl effect, which increses wi temperture e cell density of e protective culture decresing ph vlues [72] resulting in decresed [17]. dsorption of nisin molecules to e producer cells Chi-Zhng et l. [68] reported t in e presence of hence in n incresed iovilility. This response could n excess of nisin, S. ureus inntneously developed e ttriuted to cidic dmging effects on trget cells resince to e cteriocin, wheres when nisin ws concomitnt wi e higher ility soluility of dded slowly to e cells, only temporry tolernce ws nisin e increse in net positive chrge of nisin [45]. 45

9 Glol J. Biotech. & Biochem., 7 (2): 38-49, 2012 n conclusion, e dt otined in is udy 4. Pu, S., F. Hn B. Ge, soltion sugge t using comintion of o nisin L. chrcteriztion of Meicillin-resint cidophilus ws superior in improving e qulity Stphylococcus ureus rins from Louisin retil spects, exteing e shelf life inhiiting e grow mets. J. Appl. Environ. Microiol., 75: of St. ureus in minced eef. 5. Rsooli,., Food preservtion. A Nowdys, io preservtion, y using comintion iopreservtive pproch. Food Glol Science of LAB cteriocins (nisin) cteriocin-producing Books, 1: rins (L. cidophilus), cn e considered s n integrl 6. Clo-Mt, P., S. Arlio, K. Boehme, T. Miguel, prt of hurdle technology in food iury. Therefore, A. Pscol J. Brros-Velzquez, synergiic effect clerly plys role in preventing grow Current Applictions Future Tres of Lctic of pogenic spoilge microorgnisms, exteing e Acid Bcteri eir Bcteriocins for e inhiitory ctivity spectrum to such intrinsiclly resint Biopreservtion of Aqutic Food Products. Food cteri s Grm-negtive cteri rough ffecting Bioprocess Technol., 1: outer-memrne (OM) permeility, improving e 7. Elez-Mrtinez, P. O. Mrtin-Belloso, sensory, chemicl microil qulities of food Food sfety spects of pulsed electric fields, p ultimtely, hve significnt impct on food sfety, shelf 218. n: Emerging technologies for food processing. life extension hel requirements [15]. Ed. Sun, D.W. Acdemic Press, Boon. Continued reserch my led to cteriocins wi 8. Egunike, G.N. A.O. Okunjo, incresed ility enhnced fetures, or extension of Effects of processing upon e qulity of Nigerin e ntimicroil spectrum to Grm-negtive cteri. met products. Liveock Production Science, The genomics will soon ecome n essentil tool for 59: exploring e ntimicroil potency of LAB my yield 9. Prd, J.L., C.R. Cron, A.B.P. Medeiros chrcteriics t could e very rewrding from food C.R. Soccol, Bcteriocins from lctic cid sfety n economic point of view, however, ey cn cteri: purifiction, properties use s e counterproductive from e mrketing point of view, iopreservtives. nt. J. Brzilin Archives of Biology since ey will yield products- cteriocins mde y Technol., 50: genetic engineering wi ll e ssocited consumer 10. Srik, A.R., A.P. Lipton M.S. Aishwry, concerns [19]. Bcteriocin production y new isolte of Lctocillus rhmnosus GP1 uer different culture REFERENCES coitions. Advnce J. Food Science Technology, 2: Kllou,., M. Fid A.T. Ahmi, Brul, S. P. Coote, Preservtive gents in Exteing e shelf life of fresh minced cmel foods - Mode of ction microil resince met t mient temperture y Lctocillus mechnisms. nt. J. Food Microiol., 50: delruekii susp. delruekii. Electronic J. 12. Dortu, C. P. Thonrt, Bcteriocins from Biotechnology, 7: lctic cid cteri: intere for food products 2. Oloye, O.A..G. Ntuen, Spoilge preservtion. J. Biotechnol. Agron. Soc. Environ., preservtion of met: generl pprisl 13: potentil of lctic cid cteri s iologicl 13. Vignolo, G., P. Cellno, C. Belfiore S.A. Fdd, preservtives. Review Pper. nt. Res. J. Biotechnol., Review of cteriocinogenic lctic cid cteri 2: used s io-protective cultures in fresh met 3. Sperer, W.H., ntroduction to e produced in Argentin. J. Met Sci., 79: microiologicl spoilge of foods everges. n: 14. El-Nezmi, H.N. Polychronki, S. Slminen Sperer, W. H. Doyle, M. P. (Eds). Compeium H. Mykknen, Biing Rer Thn Metolism of e Microiologicl Spoilge 1 of Foods My Explin e nterction of Two Food-Grde Beverges, Food Microiology Food Sfety. Lctocillus Strins wi Zerlenone ts DO / _1, C_ Springer Derivtive {lphcute}-zerlenol. J. Appl. Environ. Science+Business Medi, LLC. Microiol., 68:

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