Acceleration Of Kachkaval Like Cheese Ripening:

Mohamed Abdel-moty Said Ahmed Noamaan

The covalent relationship between streptococci andlactobacilli as starters for processing the cheese wasestablished. Therefore,investigation of this relation in regardingto maturation of cheese may be benefit to accelerate theripening time.The enterococci having a good activity at high levelsofsalt, and by its presence as a second flora of high qualityKachkaval cheese, its role in the maturation was established.Also,the rate of proteolysiscaused by lactobacilliis greater thanthat of lactic streptococci. Therefore,additions of Ent. durans,Ent. faecalis, L. helveticus and L.easel to cheese milk or curdmay reduce the ripening time of cheese.This study was planned in order to select the proper mixedstarter that might lead to a controlled ripening acceleration witha desired properties.The research was carried out in two parts.PART I:This part of study was designed to elucidate the effectoftype of bacteria and the manner which used for adding it, onthe different properties of Kachkaval-likecheese manufacturedfrom fresh raw whole Freizian cow’s milk. The treatments weremanufactured following the same steps as the control cheeseusing 0.5% starter of L. bulgaricus and S. thennophilus exceptthat, half of the normal mixedstarter used (0.25%)was replacedby pure single culture of enterococci or lactobacilliwhen theadditions were to cheese milk. Also,when the adjunct bacterialstrains added to cheese curd pure single culture slurries at therate of I% were added throughout the shaping step ofprocessing the treatments.The main results could be summarized as follows:Throughout the processing of cheese the developed aciditywas accelerated in treatments contained sequentially, L.helveticus, Ent. faecalis and Ent durans, conaequentialyaccelerated acidity led to shortening the processing time till theend of cheddaring stage (reduction of pH values). While L. easeiretarded development of acidity and was lower than the controlcheese. The progress of acidity correlated with total bacterialcounts and type of bacteria.Adding pure single cultures of Ent durans, Ent.faecalis, L.ea,sei and L. helveticus to cheese milk or curd had no effects onthe gross chemical composition of treated cheese, the changesof fat, salt, and total nitrogen contents as well as the yield ofcheese related contrary with the changes of moisture contentduring the ripening period.All additions of bacterial strains caused higher aciditythan’ the control cheese throughout the ripening period. Theadjunct bacteria of Ent. faecalis recorded the highest levelswherein added to cheese milk or curd. which followed by L.helveticus during the maturation. The lowest acidity recorded byEnt durans followed by the late L. easeL The pH valuesdecreased gradually with proceeding of ripening time and werelower in all treatments than the control, while at the late time ofmaturation some treatments underwent some increasing in pHvalues, especially Ent faecalis, which is due to formation ofbuffering substances caused by hydrolytic products.All types of bacterial strains added to cheese milk or curdcaused proteolysis greater than the control cheese, but, it wasgreater when added to cheese milk than when added to chcCRCcurd. The faster rate of proteolysis observed throughout theearly time of ripening. In spite of L. easel recorded the lowestrate of total proteolysis, it caused deep proteolysis of cheese asNPN after fifth month of ripening. Ent. faecalis achieved thehighest proteolysis followed by L. helveticus. The adjunctbacteria hydrolyzed ctsl-casein, but, Ent. faecalis and Ent.durans had recognizedsomewhat hydrolysis effecton l3-casein.Also, in Kachkaval-llke cheese the contents of tyrosine andtryptophan as ripening indices had no consideration because ofits hydrolysis by the added bacteria, especially,Ent.faecalis.In regarding to lipolysis of treated Kachkaval-llkecheesewith bacterial strains, all cheeses achieved higher levelsof totalvolatile fatty acids than the con,trol cheese, especially,whenadded to cheese milk. Ent.faeealis recorded the highest TVFA.Some differences in the FFA were detected between thetreatments.The total and proteolyticbacterial counts were graduallyincreased with advancement of ripening, then, the numbersunderwent decreasing till the end of ripening in all treatmentsand control cheese. The total numbers were more than the.control, except, L. easeL While Ent..faecaliS possessed thegreatest counts and, also, was faster for decreasing. Concerninglipolytic counts, it was relatively low in all treatments andcontrol cheese and the counts in alltreatments were lowerthanthe control cheese, but, they were higher when bacteria addedto cheese milk than that to cheese curd.All additions improvedthe bodyand texture and flavour oftreated cheese without any effects on colour and appearanceduring the ripening. In spite of that some additions may causeslight bitterness or abnormal taste. these defects disappearedrapidly and the cheeses possessed good qualities. Tncrcforc.Ent. faecalis and L. helveiicus when added during processing thecheese it gained the highest scores When added to cheese milkor curd. But Ent. faecaliswas faster in proteolysis and causedover-ripening after five months of old. Ent.faecalis saved about51.1 % and 52.7% of ripening time and, also, L. helveticus savedabout 46.6% and 34.4%, in the same order. So, adjunctcultures contain Ent faecalis may be use for acceleratingKachkaval-like cheese ripening with particular attention to theover-ripening after five months old cheese. Also L. helveticus canbe used successfully.PART II:,This part of study was-planned to throw some light on theeffect of type ofl mixed culture which consisted of enterococciand lactobacilli (1 : IIand the manners used for adding it on thedifferent properties duning processing and ripening ofKachkaval-Iike cheese. The treatments were manufacturedfollowing the same steps as the control cheese, except that. halfof the normal starter was replaced by (0.25%1 pure mixedcultures of enterococci and lactobacllli (l : 11when the additionswere to cheese milk. And. also. the same mixtures added tocheese curd as slurries at the rate of I% during theformalization process of treated cheese.The main results could be summarized as follows:During the processing of cheese the adjunct mixedstarters caused higher acIdity than that In control cheese (thepH values related contrary with acidity percentage], but amongthe different mixtures, the variations of acidity were relativelysmall. Also, the bacterial ’counts associated with the levels ofacidity, but the cooking process spoiled most of them. then, agradual increase was observed. The time of process cheese wassomewhat reduced.All additions of mixed cultures had no effect on the mainchemical composition of cheese during ripening. The increasesof fat, salt and total nitrogen as well as the cheese yield weredue to the decreasing of moisture content during maturation.During the ripening period, all additions caused higheracidity with mixed cultures than that of the control cheese. Thehighest level of acidity achieved by mixture contained Ent.jaeealis plus L. helvetieus and the lowest by L. easel plus Ent.durans or Ent. faecalis. Also, Ent. jaeealis plus L helvetieusrecorded th•e largest level of decreasing and increasing. followedby mixture of Ent. durans plus L. helvetieus.All additions caused more proteolysis than the controlcheese, especially, during the first stage of maturation.Generally. proteolysis was more when the mixtures added tocheese curd than to cheese milk. The highest treatment wasthat contained L. helvetieus plus Eot. faecalis, followedby L.helvetieus plus Eni. durans. While the presence of L. easei withenterococci possessed lower proteolysis. There are a goodrelationship between L. helvetieus and enterococci regarding theproteolysis as obvious by determined tyrosine, tryptophan andelectrophorsis. The presence of Ent. jneealis led to littlehydrolysis of [3-caseinin its mixtures.In all treatments the TVFAwere greater than the controlcheese, also, the levels ofTVFAwere more when mixtures addedto cheese curd than that added to cheese milk. L. easei in itsmixtures with enterococci, especially,Ent. durWlS recorded thehighest total volatile free fatty acids, while L. helveticus withenterococci achieved the lowest ratios.As in part I the total, proteolytic and lipolyticbacterialcounts gradually increased, then, underwent decreasing in allcheeses. But the maximum numbers of counts were lower thanthe control cheese. The counts in treatments processed withadding the mixtures to cheese milk were more than when itadded to cheese curd. When a mixed cultures contained L.helveticus plus Ent.faecalis added to cheese milk, the resultantcheese possessed the largest number.All additions improved the body and texture and flavourcompared with the control cheese. Also,the additions had noeffect on colour and appearance. Presence of L. casei withenterococci caused a bitterness at the third or fourth month,but this little defect disappeared rapidly. Whilepresence of L.helVf!ticus with Eni. faecalis minimizedthe chance of this defect,which followed by L.helveticus plus Ent. durWlS. The additionsto cheese curd accelerated the ripening more than additions thesame mixture to cheese milk. The mixture contains L.helveticusplus. Ent. faecolis gave superior sharp typical flavoure andpossessed the greatest score points (87.1 and 92.2) and savedabout 27.8% and 41.7% of ripening time when added to cheesemilk or cheese curd respectively.So, it can be concluded that amixture consisted of L. helveticus plus Ent.faecalis may be usefor accelarating Kachkaval-like cheese without any defects, atthe rate of 0.25% beside 0.25% of normal starter to cheese milkor at the rate of 1% to cheese curd during formalizationstagethroughout the cheese manufacturing.