1 1235 Vol.52, n. 5: pp , September-October 2009 ISSN Printed in Brzil BRAZILIAN ARCHIVES OF BIOLOGY AND TECHNOLOGY A N I N T E R N A T I O N A L J O U R N A L Composition, functionl properties nd sensory chrcteristics of Mozzrell cheese mnufctured from different somtic cell counts in milk Evelise Andrett 1, Andrezz Mri Fernndes 1, Mrcos Veig Sntos 2, Cmil Mussrelli 1, Mrin Céli Mrques 1 nd Crlos Augusto Fernndes de Oliveir 1 1 Deprtmento de Engenhri de Alimentos; Fculdde de Zootecni e Engenhri de Alimentos; Universidde de São Pulo; Pirssunung - SP - Brsil. 2 Deprtmento de Nutrição e Produção Animl; Fculdde de Medicin Veterinári e Zootecni; Universidde de São Pulo; Av. Duque de Cxis Norte, 225; ; Pirssunung - SP - Brsil ABSTRACT In the present study, composition, functionl properties nd sensory chrcteristics of Mozzrell cheese produced from milk with somtic cell counts (SCC) t low (<200,000 cells/ml), intermedite ( 400,000 cells/ml) nd high (>800,000 cells/ml) levels were investigted. Three btches of cheese were produced for ech SCC ctegory. The cheeses were vcuum pcked in plstic bgs nd nlysed fter 2, 9, 16, 23 nd 30 dys of storge t 4 o C. SCC level did not ffect the moisture, ft, totl protein nd sh content, mesophilic nd psychrotrophic bcteri, nd sensory prmeters of Mozzrell cheese. However, meltbility incresed in cheese mnufctured from high SCC milk. Results indicted tht rw milk used to produce Mozzrell cheese should not contin high SCC (>800,000 cells/ml) in order to void chnges in the functionl properties of the Mozzrell cheese. Key words: somtic cell count, Mozzrell cheese, qulity evlution, functionlity INTRODUCTION The inflmmtion of the mmmry glnd, or mstitis, is one of the most importnt fctors tht cn negtively ffect the rw milk qulity (Interntionl Diry Federtion, 1987). Milk from infected cows is chrcterized by incresed somtic cell counts (SCC) (Auldist nd Hubble, 1998). The impct of mstitis to the diry production is relted to chnges in milk composition, such s reduced clcium, lctose nd csein levels, nd increses in sodium, chloride, nd levels of serum proteins. However, one of the most importnt dverse effect of high SCC milk on the diry industry include reduced shelf life of diry products, due to undesirble sensory ttributes (Kitchen, 1981). The SCC in milk mrkedly influences the overll qulity of cheeses. Min ltertions include: decresed cheese yield, incresed ft nd protein loss in whey (Brbno et l., 1991) nd inferior orgnoleptic properties (Lee et l., 1991; Auldist et l., 1996). SCC effects on cheese mnufcture hve been well estblished for Cheddr Author for correspondence:
2 1236 Andrett, E. et l. (Grndison nd Ford, 1986; Mitchell et l., 1986; Rogers nd Mitchell, 1994; Politis nd Ng-Kwi- Hng, 1988) nd Cottge (Klei et l., 1998) vrieties. However, very little informtion is vilble on the effects of mstitis nd high SCC milk on the qulity of other vrieties, such s Mozzrell cheese. Mozzrell cheese is commonly used s ingredient for pizz, nd contributes to the orgnoleptic chrcteristics of the finl product (Kindstedt, 1993). The bility of cheese to fulfill its expected requirements s n ingredient is relted to its functionl properties (Fox et l., 2000). Functionlity prmeters of Mozzrell cheese include meltbility nd free oil formtion. Melting chrcteristics of the cheese re the prime fctors in determining the pproprite pizz bking (Kuo et l., 2000). The excessive oiling off, or the tendency to form excessive free oil upon melting, is defect tht detrcts from melted cheese ppernce on pizz nd relted foods (Kindstedt nd Rippe, 1990). There is no previous report on the effects of somtic cell counts on meltbility nd free oil formtion of Mozzrell cheese. In Brzil, Mozzrell cheese ccounts for nerly 35% of the 375,000 kg of the totl cheese produced in the country. The potentil impct of high SCC in milk on the Mozzrell industry is not well understood. Therefore, the im of the present study ws to verify the effects of using different bulk milk SCC on the composition, microbiology, functionlity nd sensory chrcteristics of the Mozzrell cheese. MATERIALS AND METHODS Milk collection Milk used in the present study ws collected from two diry herds locted in Pirssunung, Brzil. Holstein cows were selected mong the nimls tht were in intermedite stges of lcttion, nd tht were not submitted to ntibiotics tretment seven dys before milk collection to void the residues in milks (Brito nd Junqueir, 2006). Milk from individul cows ws submitted to SCC using n electronic counter (Bentley, USA), to llow its distribution in three groups bsed on individul SCC sttus: cows with low SCC (<200,000 cells/ml), intermedite SCC ( 400,000 cells/ml) nd high SCC (>800,000 cells/ml). Groups of cows of ech SCC ctegory were milked seprtely, two dys fter SCC mesurement, to obtin milk for cheese processing. Milk collected from cows of the sme group ws bulked until minimum mount of 100 kg ws reched. Milk ws then cooled nd stored in refrigertor (4 o C) until utilistion (24 h fter collection). Duplicte smples of bulked rw milk of ech SCC ctegory were nlysed for composition (Assocition of Officil Anlyticl Chemists, 1995) nd confirmtion of SCC in the electronic counter (Bentley, USA). Mnufcture of Mozzrell cheese The mnufcture of cheese ws ccomplished in two dys, strictly following the procedures s described by Oliveir (1986). On dy one, the rw milk (100 kg/scc level) ws het treted t 65 o C for 30 min, nd then cooled to nerly 34 o C. All the procedures for the mnufcture of cheese were performed in double-jcketed stinless steel vt (Mec Milk, Brzil). Mesophilic nd psychrotrophic bcteri were nlysed on psteurised milk (Americn Public Helth Assocition, 1992) for confirmtion of milk bcteril counts. Psteurised (65 o C for 30 min) milk smples contining less thn 1.0x10 2 colony forming units per ml of mesophilic or psychrotrophic bcteri were inoculted (3% inoculum) with thermophilic strter culture (TCC- 20, Christin-Hnsen, Brzil) nd clcium chloride solution (250 mg/l), mixed nd incubted t 34 o C, for pproximtely 60 min. Forty milliliters of liquid rennet contining chymosin nd pepsin (H- L, Christin-Hnsen, Brzil) ws dded to the milk, followed by mixing thoroughly for one minute nd incubting t 34 o C for 35 min. After tht, the cogulum ws cut into smll cubes of pproximtely 1.0 cm nd gently stirred for 10 minutes, followed by cooking t 43ºC for 25 minutes. At the end of cooking, the whey ws drined nd collected for the nlysis. All fines in the whey were dded bck into the vt. The curd ws then removed from the vt, plced in polypropylene try nd covered with plstic film. The trys were stored in refrigertor t 4ºC for h, until ph (Fox et l. 2000). On dy two, the cheese curd ws cut into slices of nerly 0.5 cm thickness nd plced in vt contining wter t 80-85ºC. The curd ws stretched nd kneded for 5 min, when it reched the typicl elstic consistency of the Mozzrell cheese. The hot, plstic curd ws then mnully molded into rectngulr blocks of 4 kg, cooled in
3 Composition, functionl properties nd sensory chrcteristics of Mozzrell cheese 1237 sterile cold wter to 10ºC, nd brine slted (20ºB) for 20 h. After slting, the cheese ws dried for 48 h in refrigertor t 4 o C, vcuum pcked in polyethylene bgs, nd stored for 30 dys. The experiment ws replicted three times, once per month, representing nine btches of cheeses, three within ech SCC ctegory. Anlyses of Mozzrell cheeses were performed in duplicte smples fter 2, 9, 16, 23 nd 30 dys of storge t 4ºC. Composition nd microbiologicl nlysis Cheese moisture, ft, totl protein nd sh were determined on dy 2 of storge ccording to the Assocition of Officil Anlyticl Chemists (1995) methods. Microbiologicl tests included stndrd plte count for mesophilic nd psychrotrophic bcteri (Americn Public Helth Assocition, 1992). Functionl properties Functionl properties of Mozzrell cheese were evluted by mens of free oil nd meltbility determintions. Free oil ws mesured using modified Gerber method, s described by Kindstedt nd Fox (1991). A modified Schreiber test (Kosikowski, 1982) ws used to quntify cheese meltbility. Sensory nlyses Smples of Mozzrell cheese were submitted to non-trined pnel of 50 individuls (Institute of Food Technologists, 1981) recruited mong the students nd stff of the University of São Pulo. Smples were cut into portions of pproximtely 30 grms nd submitted to the pnel without ddition of ny other ingredients, t pproximtely 10 o C. Pnelists were unble to identify the smples nd were instructed to follow hedonic scle of 9 points nd ttribute scores to ech of the following cheese chrcteristics: ppernce, consistency, odour nd tste. The descriptions used for the hedonic scle were: 9=excellent, 8=very good, 7=good, 6=firly good, 5=indifferent, 4=firly poor, 3=poor, 2=very poor, 1=extremely poor. Sttisticl nlyses Results on milk nd cheese composition of the nine btches were submitted to one-wy ANOVA (Gcul nd Singh, 1984) nd tretment mens were compred by the Tukey test, using the SAS Generl Liner Model (SAS Institute, 2004). A split-plot design ws used to monitor the effects of tretment, storge time, nd the interction of the functionl properties nd sensory grdes of cheeses t intervls during the 30 dys of storge. Anlysis of vrince for the split-plot design ws crried out using the PROCMIXED of SAS softwre (SAS Institute, 2004). Sttisticl significnce ws ccepted t P<0.05. The ANOVA models used for the sttisticl nlysis of functionl nd sensory chrcteristics re listed in Tble 1. Tble 1 - The ANOVA models used for the nlysis of functionl nd sensory chrcteristics. Model terms df Anlysed s Error term SCC 2 Whole plot fctor (fixed) E () E () 12 Whole plot error T 4 Subplot (fixed) E (b) SCC x T 8 Interction (fixed) E (b) E (b) 96 Subplot error Model eqution Y = SCC + E () + T + SCC x T + E (b) SCC = somtic cell counts, E = error, nd T = time of storge. RESULTS AND DISCUSSION The results of composition nlyses of rw milk used for the Mozzrell cheeses production in ech SCC ctegory re presented in Tble 2. Averge SCC in low, intermedite nd high SCC milk smples differed sttisticlly (P<0.05), with verge of 5.15 log cells/ml, 5.67 log cells/ml nd 6.02 log cells/ml, respectively. No significnt differences were detected between the evluted chrcteristics for the different milks studied (P>0.05), except for the ft nd totl protein content, which were higher (P<0.05) in high SCC milk. A higher ft nd totl protein content of milk with high SCC hs been described previously by Mrques et l. (2002) nd Auldist et l. (1995), respectively. The composition nd microbiologicl prmeters of Mozzrell cheese produced from milk of ech SCC ctegory re shown in Tble 3. No effect
4 1238 Andrett, E. et l. (P>0.05) of milk SCC ws observed on the moisture, ft, totl protein nd sh, s well s mesophile counts. Psychrotrophic bcteri were not detected in the cheeses on dy 2 of storge. Tble 2 - Composition of cow milk used for the mnufcture of Mozzrell cheese within selected somtic cell count ctegories 1. Prmeter SCC Ctegory (cells/ml) < 200, ,000 > 800,000 MSD 2 Somtic cell count (log cells/ml) c b Titrtble cidity ( o D) Totl solids (%) Ft (%) b b Totl protein (%) b b Lctose (%) Within row, mens followed by the sme letter re not significntly different (P>0.05). 1 Men + stndrd devition of duplicte nlyses of three lots of ech SCC ctegory. 2 MSD = Tukey s minimum significnt difference t α=0.05. Tble 3 - Composition nd microbiologicl chrcteristics of Mozzrell cheese mnufctured from milk within selected somtic cell count ctegories 1. Prmeter SCC Ctegory (cells/ml) < 200, ,000 > 800,000 MSD 2 Moisture (%) Ft (%) Totl protein (%) Ash (%) Mesophiles (log CFU/g) Within row, mens followed by the sme letter re not significntly different (P>0.05). 1 Men + stndrd devition of duplicte nlyses of three lots of ech SCC ctegory nlysed on dy 2 of storge. 2 MSD = Tukey s minimum significnt difference t α=0.05. Tble 4 presents the free oil vlues of Mozzrell cheeses during 30 dys of storge. SCC did not ffect the free oil formtion (P>0.05) nd no interction ws found between SCC nd the dys of storge (P>0.05). However, significnt increse in free oil relese ws observed during the storge (P<0.05). Tble 4 - Effect of somtic cell counts (SCC) on free oil relese, s percentge of Mozzrell cheese ft, during storge t 4 C 1. Time of storge (dys) SCC (cells/ml) (g/kg of cheese ft) < 200, , > 800, Stndrd error Source of vrition P SCC Time SCC x time 1 Mens of duplicte nlyses of three lots of ech SCC ctegory. * Liner effect: y = x (R 2 = 0.32) *
5 Composition, functionl properties nd sensory chrcteristics of Mozzrell cheese 1239 The mount of free oil relesed from Mozzrell depended on the proteolysis level during the storge, nd the excess of free oil on the surfce of pizz fter bking ws mjor qulity defect for Mozzrell cheese mnufcturers (Kindstedt nd Rippe, 1990). Oiling off occurs when the csein mtrix collpses during the heting, llowing the ft globules to colesce nd to flow to the surfce. In the present study, SCC hd significnt effect (P<0.05) on the meltbility of cheeses (Tble 5). The increse in the melted dimeter of cheeses is relted to the proteolysis in cheese during storge (Tunick et l., 1993). Therefore, s the mtrix ws degrded by the proteolysis, the bility of the cheese to mintin its structure during heting decresed. There hs been no previous evidence tht the differences in milk composition, s observed in the present experiment for protein nd ft content in the high SCC milk, my ply significnt role in the meltbility of Mozzrell cheese. The high meltbility observed in high SCC cheeses could led to higher fluidity of melted cheese, which might cuse ltertions in spred chrcteristics of cheese, leding to lower cceptnce from the consumers (Pizi et l., 2003). The melted dimeter of cheeses incresed up to 30 dys of storge (P<0.05), nd there ws significnt interction between SCC nd time of storge (P<0.05). In fct, ge hs lrge impct on the meltbility of cheeses (Kindsted, 1993). Soon fter the mnufcture of the cheese, proteins hve high moleculr weight nd consequently lower solubility. After two or three weeks, proteins re hydrolysed nd meltbility is incresed until become excessive nd inpproprite (Oliveir, 1986; Kindsted, 1993). Although the csein nd the proteolysis index of Mozzrell cheeses ws not evluted in the present study, the higher meltbility of high SCC cheeses could be consequence of higher protein degrdtion, since previous reports indicted tht proteolysis ws incresed in Cheddr cheese mnufctured from milk with 500,000 cells/ml (Rogers nd Mitchell, 1994), in Cottge cheese mde with milk t 872,000 cells/ml (Klei et l., 1998), nd in Prto cheese mde from milk with > 600,000 cells/ml (Mzl et l., 2007). Tble 5 - Effect of somtic cell counts (SCC) on the melted dimeter (mm) of Mozzrell cheese during storge t 4 C 1. Time of storge (dys) SCC (cells/ml) (mm) < 200, , > 800, Stndrd Error Source of vrition SCC Time SCC x time P * < ** < *** 1 Men of duplicte nlyses of three lots of ech SCC ctegory. * Liner effect: y = x (R 2 = 0.99). ** Liner effect: y = x (R 2 = 0.78). *** Liner effect: < 200,000: y = 0.10x (R 2 = 0.44); 400,000: y = 0.231x (R 2 = 0.74); > 800,000: y = 0.27x (R 2 = 0.72). Figure 1 presents the men grdes of sensoril chrcteristics of Mozzrell cheeses for the three SCC studied. SCC in milk influenced the ppernce nd consistency of cheeses (P<0.001 nd P=0.0107, respectively). Compred with the low nd high SCC ctegories, cheeses mde with intermedite SCC milk hd higher grdes for the ttribute ppernce (P<0.05). The men grde of intermedite SCC cheeses for consistency ws higher (P<0.05) thn the high SCC group. However, no differences (P>0.05) were found between the grdes of ll sensory ttributes in low nd high SCC cheeses. Lee et l. (1991) nd Auldist et l. (1996) reported lower sensory chrcteristics of Cheddr cheese mde from SCC milks t levels bove 1,500,000 cells/ml, which ws much higher thn the levels used in the present experiment. Also, possible explntion
6 1240 Andrett, E. et l. for the difference between those reports nd dt obtined in the present study could be the different ripening ptterns mong cheese vrieties. Mozzrell is short-ripened cheese tht is relesed for consumption 2-3 dys fter mnufcture, while Cheddr cheese is usully mtured t 6-10 o C for period rnging from 3-4 months to two yers (Fox et l., 2000). This long period would llow the prolonged ction of proteolytic enzymes present in high SCC milk, leding to greter sensory modifiction in Cheddr when compred to the Mozzrell cheese. The grdes for ll the sensoril chrcteristics evluted significntly incresed during 30 dys of storge (Fig. 2). The P vlues were , , < nd < for ppernce, odour, consistency nd tste, respectively. The reson for the increse in odour nd tste grdes might be due to the ction of strter culture during the storge. 7,20 7,00 Grdes 6,80 6,60 6,40 b b b b 6,20 6,00 5,80 Appernce Odour Consistency Tste Chrcteristics 200,000 cells/ml 400,000 cells/ml 800,000 cells/ml Figure 1 - Effect of SCC on sensory ttributes of Mozzrell cheese during 30 dys of storge. Results re men grdes with brs of stndrd error of individul scores obtined from 50 pnellists. Within ech sensory ttribute, mens followed by the sme letter re not significntly different (P>0.05). 7,20 7,00 Grdes 6,80 6,60 6,40 6,20 6,00 5,80 5, Dys of storge Appernce Odour Consistency Tste Figure 2 - Sensory chrcteristics of Mozzrell cheese on dys 2, 9, 16, 23 nd 30 of storge. Results re men grdes of individul scores obtined from 50 pnellists.
7 Composition, functionl properties nd sensory chrcteristics of Mozzrell cheese 1241 The interction between SCC nd dy of storge ws observed only for the ppernce of cheeses (P<0.0001). The liner regression lines predicting the grdes ccording to the interction between SCC nd time were X (R 2 =0.44) for cheese mde from milk with low SCC, X (R 2 =0.91) for intermedite SCC cheese, nd X (R 2 =0.28) for the cheeses from the high SCC ctegory, where X is the dys of storge. CONCLUSIONS Results of this study indicted tht SCC in milk ws not mjor fctor tht could negtively ffect the composition nd sensory chrcteristics of Mozzrell cheese over 30 dys of storge. However, incresed SCC in milk led to higher meltbility tht could result in lower qulity of Mozzrell cheese intended for use s ingredient, especilly for pizz. Bsed on these results it could be suggested tht cow milk used to produce Mozzrell cheese should not contin SCC over 800,000 cells/ml in order to void inferior functionl properties of the Mozzrell cheese. ACKNOWLEDGEMENTS The uthors thnk the Fundção de Ampro à Pesquis do Estdo de São Pulo (FAPESP, Brzil; grnts no. 2003/ nd 2003/ ) for the finncil support. RESUMO No presente estudo form investigds composição, s proprieddes funcionis e s crcterístics sensoriis do queijo Mussrel produzido prtir de leite com contgens de céluls somátics (CCS) em níveis bixos (< CS/mL), intermediários ( CS/mL) e ltos (> CS/mL). Form produzidos 3 lotes de queijo pr cd CCS. Os queijos form embldos vácuo e nlisdos pós 2, 9, 16, 23 e 30 dis de rmzenmento 4 o C. O nível de CS não fetou umidde, os teores de gordur, proteín totl e cinzs, os níveis de bctéris mesófils e psicrotrófics, e os prâmetros sensoriis do queijo Mussrel. Entretnto, houve umento d cpcidde de derretimento no queijo fbricdo com leite de lt CCS. Os resultdos indicm que o leite cru utilizdo pr produção de queijo Mussrel não deve conter níveis de CS cim de /mL, pr evitr lterções ns proprieddes funcionis do queijo Mussrel. REFERENCES Americn Public Helth Assocition (1992), Stndrd Methods for the Exmintion of Diry Products. 16th Edition. Wshington D C: APHA. Assocition of Officil Anlyticl Chemists (1995), Officil Methods of Anlysis. 16th Edition. Arlington VI: AOAC. Auldist, M. J. nd Hubble, I. B. (1998), Effects of mstitis on rw milk nd diry products. Austr. J. Diry Technol., 53, Auldist, M. J.; Cots, S.; Rogers, G. L. nd McDowell, G.H. (1995), Chnges in the composition of milk from norml nd mstitic diry cows during the lcttion cycle. Austr. J. Exp. Agric., 35, Auldist, M.J.; Cots, S.; Sutherlnd, B.J.; Myes, J.J.; McDowell, G. H. nd Rogers, G. L. (1996), Effects of somtic cell count nd stge of lcttion on rw milk composition nd the yield nd qulity of cheddr cheese. J. Diry Res., 63, Brbno, D. M.; Rsmussen, R. R. nd Lynch, J. M. (1991), Influence of milk SCC nd milk ge on cheese yield. J.Diry Sci., 74, Brito, R.B. nd Junqueir, R.G.. (2006), Determintion of bet-lctm residues in milk by high performnce liquid chromtogrphy. Brzilin Archives of Biology nd Technology., 49, Fox, P. F.; Guinee, T. P.; Cogn, T. M. nd McSweeney, P. L. H. (2000), Fundmentls of Cheese Science. Githersburg: Aspen Publishers. pp Gcul, J. R. nd Singh, J. (1984), Sttisticl Methods in Food nd Consumer Reserch. Orlndo: Acdemic Press. pp Grndison, A. S. nd Ford, G. D. (1986), Effects of vritions in somtic cell count on the rennet cogultion properties of milk nd on the yield, composition nd qulity of cheddr cheese. J.Diry Res., 53, Institut of Food Technologists (1981), Sensory evlution guide for testing food nd beverge products. Food Technol., 35, Interntionl Diry Federtion (1987), Bovine mstitis definition nd guidelines for dignosis. Bulletin Int. Diry Fed., 211, 7. Kindstedt, P. S. nd Rippe, J. K. (1990), Rpid quntittive test for free oil (oiling off) in melted Mozzrell cheese. J. Diry Sci., 73,
8 1242 Andrett, E. et l. Kindstedt, P. S. (1993), Mozzrel nd pizz cheese. In: Cheese: Chemistry, Physics nd Microbiology. 1st Edition. (Ed PF Fox). London: Elsevier Applied Science. pp Kindstedt, P. S. nd Fox, P. F. (1991), Modified Gerber test for free oil melted Mozzrel Cheese. J. Food Sci., 56, Kosikowski, F. V. (1982) Cheese nd fermented milk foods. 3th Edition. Ann Arbor, MI: Edwrds Bros. pp Kitchen, B. J. (1981), Reviews of the progress of diry science: Milk compositionl chnges nd relted dignostic tests. J. Diry Res., 48, Klei, L.; Yun, J.; Spru, A.; Lynch, J.; Brbno, D.; Sers, P. nd Glton, D. (1998), Effects of milk somtic cell count on Cottge cheese yield nd qulity. J. Diry Sci., 81, Kuo, M. I.; Wng, Y. C. nd Gunsekrn, S. (2000), A viscoelsticity index for cheese meltbility evlution. J. Diry Sci., 82, Lee, S. C.; Yu, J.H.; Jeong, C. L.; Bck, Y. J. nd Yoon, Y. C. (1991), The influence of mstitis on the qulity of rw milk nd cheese. Koren J. Diry Sci., 13, Mrques, L. T.; Blbinotti, M. nd Fischer, V. (2002), Vritions in the milk chemicl composition ccording to somtic cell count. In: II Pnmericn Congress on Milk Qulity nd Mstitis Control, Ribeirão Preto: IFC/Milkpoint. Mzl, G.; Vinn, P. C. B.; Sntos, M. V. S. nd Gignte, M. L. (2007), Effect of somtic cell count on Prto cheese composition. J. Diry Sci., 90, Mitchell, G.E.; Fedrick, I.A. nd Rogers, S.A. (1986), The reltionship between somtic cell count, composition nd mnufcturing properties of bulk milk. Cheddr cheese from frm bulk milk Austr. J. Diry Technol., 41, Oliveir, J. S. (1986), Cheese: Technologicl fundments. 2nd Edition. Cmpins: Unicmp. pp. 146 Pizi, P. D.; Spdoti, L. M.; Nrimtsu, A.; Dornells, J. R. F. nd Roig, S. M. (2003), Composition, proteolysis, meltbility nd blisters formtion of Mozzrell cheese obtined from trditionl nd ultrfiltrtion methods. Ciên. Tecnol. Alim., 23, Politis, I. nd Ng-Kwi-Hng, K. F. (1988), Effects of somtic cell counts nd milk composition on cheese composition nd cheese mking efficiency. J. Diry Sci., 71, Rogers, S. A. nd Mitchell, G. E. (1994), The reltionship between somtic cell count, composition nd mnufcturing properties of bulk milk. 6. Cheddr cheese nd skim milk yoghurt. Austr. J. Diry Technol., 49, SAS Institute (2004), SAS User s Guide: Sttistics. Cry, NC: SAS Institute Inc. Tunick, M. H.; Mckey, K. L.; Shieh, J. J.; Smith, P. W.; Cooke, P. nd Mlin, E. L. (1993), Rheology nd microstructure of low-ft Mozzrell cheese. Int. Diry J., 3, Received: Mrch 27, 2007; Revised: July 24, 2007; Accepted: October 27, 2008.