cheese specialties

Metija under optical microscope ( GX100 )III -11 , the apparent viscosity of the pastewhile increasing the speed of the scraperpara- caseinfat globules and improving their distributionand improving hydration( 1253 mPa ) at a speed corresponding to piges para - casein start competingwater This promotes the swelling of the starch granulesviscosity , and on the other hand the hydration of paraal. (1989 ) , the presence of melting salts may also influencemaintaining the pH at the correct value ,hasResults and Discussion55tinue and guarantee. 2003) , the breakdown oftreatments and shearA) in the swollen state , ( b), Which influences the( NORONHA et al.in the matrixviscosityin the dough ;, Anparaaincreasing theirbResults and Discussion56ability to sequester calcium and also the number of negative charges responsible forelectrostatic repulsion of the para- casein (LU et al. , 2008).For Ladhidh Camembert , Figure III -12 shows that the apparent viscosityincreases at the beginning of creaming and it reaches a threshold of 1049 mPas , a decrease thereaftercan be recorded and stabilizes at 510 MPa . These results show that this product has aviscosity less than Metija , which may be due to the likely presence of theor absence of crosslinked starch on viscosity increase of the cheese paste .The effect of temperature and humidity can be added in the presence or absence ofcrosslinked starch . In the same context , GLIGUEM et al. (2009 ) reported thatincreasing moisture content results in a decrease in viscosity .The effect of above 95 ° C, may be the cause of slightreduction of apparent viscosity when the speed of the scraper was 80 % . The workby JELEN et al. (1995 ) and Singh (1995 ) , indicate that the high temperatures generatepolyphosphates thermal hydrolysis and denaturation of proteins andconsequent reduction in the hydration of para- casein as well as the degree of emulsificationof the fat .According to literature data ( Kuhan and SCHULAUCH 1994; Nayouf , 2003),shear forces may reach high temperatures and to decrease the viscosity arefollowing the break- crosslinked starch grains (Figure III- 10b) ; UHT heat treatmentapplied during the manufacturing process was 138 ° C which is a temperature abovethe maximum temperature ( 130 ° C ) in which the crosslinked starch can withstand the forces andtoo high agitation cause the breakdown of starch granules , resulting in a lossviscosity .DIMITRELI THOMAREIS and (2004 ) , reported that the fat does not affectsignificantly to the apparent viscosity during the manufacturing process of thespecialty cheese . By cons , WARNER ( 1981) showed that at high concentrations,glycerol increase the viscosity of the aqueous phase; he manifested a plasticizing effectcomparable to that of water . It consists of three carbons having three hydroxyl functionscould replace the water of hydration of the proteins occupying binding sitesWater molecules on the protein molecules , resulting in an increase inviscosity .Results and Discussion57Cheese specialty Metija has a higher viscosity than the specialtyCamembert cheese Ladhidh that does not contain crosslinked starch. Despiteincreasing the viscosity , the desired cheese paste exhibited machinability andposed no problems of clogging of UHT sterilizer .Figure III -11. Evolution of the apparent viscosity during creaming cheese specialtyMetijaFigure III -12. Variation of the apparent viscosity of the cheese specialty Ladhidhcamembert for creaming1.10 . Flow propertiesThe results on the rheology showed that the yield point issignificantly ( p < 0.05) different between the two cheese specialties ; it was 124.33 ±92910981230 1253 1217 1247020040060080010001200140060 65 70 75 80 85 90Viscosity ( mPa )Scraper speed ( % )80710498105105100200400600800100012005 10 15 20 25Viscosity ( mPa )Time (min)Results and Discussion58138.33 ± 5.13 mm and 3.06 mm for Metija ( 58.01 ± 0.20 % moisture) and the LadhidhCamembert ( 60.16 ± 1.94 % moisture ), respectively. These results can be considered veryclose to those obtained by Hennelly et al . (2005 ) . These authors reported that 54%moisture (g/100 g ) , the flow was 126 mm. Furthermore , MOUNSEY et al . (2008)shown in their work that cheese specialties (at a moisture content of 48.90 ± 0.21% ) , Showed a flow of 112.9 ± 3.30 mm in the presence of pregelatinized starch inthe formula, and 185.6 ± 9.80 mm without the use of starch in the recipe.From these results it is clear that the flow properties arestrongly related to moisture content in the cheese product and the presence of starchcrosslinked in formula; during the process of manufacturing cheese specialties ,the rapid immobilization of the water by the cross-linked starch granules probably preventscasein hydration resulting in aggregation . DELLA VALLE et al. (1996)shown that the ratio of amylose to amylopectin an important role in the rheological casestarch-based products and the proportion of amylose was directly viscosityproduct and conditioned the sensitivity of the product to moisture , mechanical energy andtemperature.The flow difference between Metija and Ladhidh Camembert can be attributed toinequality humidity and the presence of cross-linked starch ; at 58 % moisture , waterappears fully absorbed by the crosslinked starch granules and involved in the hydrationcasein , but up to 60 % moisture , the starch swelling and hydrationproteins reach their maximum and free water will be more abundant and play a roleplasticizer giving the product a flowing character .The water content of the cheese can not explain alone the flow propertiesbut also the pH and the salt (NaCl) can influence the rheology of specialtiescheese . At pH < 6, NaCl decreases the net charge of the protein and modifies cheeseprotein - protein interactions and protein - water. Caseins and whey proteinscomponent cheeses undergo a decrease in hydration capacity byapproximating pH 5.0 ( CARIC KALAB and 1987). All these changes affect thethree-dimensional protein network forming the backbone of cheeses. The flowincrease as the result of the increased hydration of the proteins in the presence of low concentrationsto decrease salt and high salt concentrations which competes with proteinsfor water. The predominance of water-salt interactions at the expense of water - protein interactionsResults and Discussion59cause the dehydration of proteins at high levels of salt ( Cheftel et al.1985) . Furthermore , due to its ionic nature in water, the NaCI may decrease propertiescheeses flow preventing both molecular and hydration expansionproteins . The action of NaCl would Mitigation intramolecular repulsive forces andStabilization of the quaternary structure of the proteins. Increasing the ionic strengththe medium in the presence of the salt also decreases water absorption and protein solubility( URBANSKI et al . 1983).conclusionCheese specialty is a hybrid physical-chemical system, so highlyunstable , wherein the fat is dispersed and proteins still are roughlygelled depending on the desired texture which is highly influenced by the constitution of theformula but also by the various treatments that formula had suffered. The presence ofcrosslinked starch in the formula Metija gives it a high viscosity and a flowweak. However, the degree of crosslinking seems insufficient and may cause harm totexture of the finished product because of the seepage phenomenon which can be generated by the burststarch grains which could not withstand the shear forces and severe treatment.2 . BACTERIOLOGICAL ANALYSESCheese specialties are complex foods usually obtainedmixing one or more varieties of natural cheeses with emulsifying agents ( saltsmelting ) , various optional ingredients including dairy ingredients , and water . thefinal product characterized by a content of water , a slightly acidic pH and water activity(Aw) high and packed in tightly closed, presents risksand microbial activity especially of clostridia and other microorganismsanaerobes.2.1 . Microbiological analyzes for the manufacturing process of MetijaAccording to the results shown in Table III-2 , raw materials constituting themixture are highly contaminated with total coliforms , fecal coliforms,staphylococci and anaerobic spores gasifiers (SAG) , the abundant presence of these organismsin the mixture tells us about a hygiene problem in the local storage ofconditions and cutting tools . During the prebaking , a decrease in the loadmicrobial can be noticed and become countable colonies ; it is noted that thecontamination level was 190 CFU / g of product for total coliform bacteria 140Results and Discussion60/ G for fecal coliforms , 40 CFU / g for Staphylococci and gas production isalso noted indicating the presence of anaerobic spores gasifiers . This can be explained by theThermal destruction of the vegetative form of the microorganism . Precooking seemsinsufficient for the total elimination of microbial flora, but the UHT treatment iseffective and no seed or spore have been detected, which gives us an indication of the goodpractice of UHT treatment. The absence of coliforms, staphylococci and SAGpersists until finished to the output of the conditioner due to the high temperatures produced at theoutput UHT sterilizer and aseptic conditions, safety and good conditionhygiene of the conditioner , staff and the whole workshop .Table III -2. Analytical results microbiologies during the manufacturing process of Metijacoliformstotal / gcoliformscoliforms / g Staphylococci / g anaerobic sporesgasifiers (SAG)Mixer + + + + + + +Precooking 190 140 40 +UHT Absence Absence Absence AbsenceFinished product Absence Absence Absence Absence2.2 . Microbiological analyzes during the manufacturing process Ladhidh CamembertControl of the microbiological quality of Ladhidh Camembert was made afterthree main steps of the manufacturing process ; after grinding , after baking and afterconditioning ( in the finished product ) .The results obtained ( Table III -3 ) show that the first material may representa major risk of contamination of the finished product, the degree of contamination by bacteriacoliforms can be linked to hygiene conditions in which the preparation and conducthandling of raw materials .Therefore , the step of cooking will determine the microbiological quality of the finished product .The negative result of the enumeration of coliforms , staphylococci anaerobic sporesgasifiers cooking end confirms the effectiveness of this operation which is carried out at 90 ° C andvapor injected at 110 ° C. Water These results also indicate that no germs or spores havebeen identified in the finished product .Results and Discussion61Table III-3 . Analytical results microbiologies during the manufacturing process ofLadhidh Camembertcoliformstotal / gcoliformscoliforms / gStaphylococci / ganaerobic sporesgasifiers (SAG)After grinding + + + + + + +After cooking Absence Absence Absence AbsenceFinished product Absence Absence Absence AbsenceconclusionThe presence of spores and vegetative forms including Clostridium( from natural cheeses or other raw materials) in the specialtiescheese can cause a major health risk , if favorable conditionsgermination met namely the activation temperature of the spores , anaerobiosis , pHrelatively high and (Aw ) adequate . The results of microbiological analyzes revealedthe cheese specialties showed good microbiological quality throughthe application and the effectiveness of heat treatment ( UHT treatment and baking ) .3 . SENSORY ANALYSESAfter tracking changes in physicochemical parameters during the process ofmanufacture of two cheese specialties ; Metija , part of the protein material issubstituted cross-linked starch , and Ladhidh camembert which does not contain starch,we are interested in rheological behavior in terms of viscosity andflow . Subsequently, we subjected these products to sensory appreciation. inFirst, a triangle test was conducted to determine whether there areperceptible differences between the sample and another one side , and for determiningthe ability of tasters to distinguish between differences in appearance , odor , flavor orFood texture of another side . Subsequently , a test of rank order which hasobjective to classify and locate our product compared to three other cheese specialties( Peasant Quisto and Cheezy ), and finally a hedonic test to determine the presence orthe absence of correlations between physicochemical parameters and sensory profile.Results and Discussion623.1 . triangular testWhen all the tasters had finished the test, we indicated the correct answer witha (+) when they had clearly identified the separate sample or a (-) in the case ofwrong answers. The results were presented in tabular form (Table III -4). inusing the Statistical Annex Table 9 , we compared the total number of tasterswith good responses ( X) the total number of tasters (n) and determined the level ofmeaning.Table III-4 . Results of the triangular testtaster Result1 -2 -3 -4 ⁺5 ⁺6 ⁺7 ⁺8 ⁺9 ⁺Total correct answers = 6The Appendix table 9 shows that for a set of 9 and 6 tasters goodresponses , the probability is 0.042 with a significance level of 5% . asgenerally believed that it takes a probability equal to or less than 0.05 for the difference issignificant , we conclude that the difference between the samples was significant atprobability of 5% , as 6 of the 9 tasters were well chosen sample is differentthe probability was 0.042 ≤ 0.05. This difference is probably attributed toincorporation of the crosslinked starch in formula Metija cheese specialty , itassigns special by giving him a different quality compared to the other sample .The results of this test allows us to conclude that the particular tastersa significant ability to distinguish between differences in appearance, odor, flavor orFood texture .Results and Discussion633.2 . Placement TestWe asked tasters to rank the taste samples in termsacceptability without giving equality by giving each sample a different dimension evenit seemed comparable . The sample in which the most palatable were granted to seegive a rating of 1 , the next dimension 2 and one who seemed the least acceptable rating 3 andlast score 4. ratings ranking data for each sample by 09 tasterswere grouped in tabular form (Table III -5).Table III -5. Test results rank top five cheese specialtiestasterSamplesA B C D E1 2 4 3 5 12 2 3 5 4 13 1 3 4 5 24 1 3 4 5 25 3 2 5 4 16 2 1 4 5 3January 7 2 5 3 48 3 5 1 4 2September 3 2 4 5 1totalranking 18 25 35 40 17Rating 2 3 4 5 1Differences between totals pairwise ranking were:A - E = 18-17 = 1B - E = 25 to 17 = 8C - E = 35-17 = 18D - E = 40-17 = 23D - A = 40-18 = 22D - B = 40-25 = 15D - C = 40-35 = 5C - A = 35-18 = 17C - B = 35-25 = 10B -A = 25 to 18 = 5The critical value calculated forfrom the table of Annex 10Differences between totals pairwise rankingsignificant differences ( differences < 19)( B and E ) , ( C and E ) , ( D and B ) , ( C and D ) , ( A and C ) , ( B and C )( D and A) and ( D and E ) , it is found that the differencethat is to say ≥ 19 .We conclude that the tasters classifiedpreferably according to the intensity of tastecheese Metija coded with the letter Afollowed by those encoded by the letterlast.3.3 . hedonic testThe results of the hedonic test are reANOVA ( ANOVA details are given in Annex 13 and 14)no significant differenceslatter have been grouped into one homogenous group (Figure III -13. average values02468apreciation hedonicp ≤ 0.05 (09 tasters and 05 samples10 .pairs showbetween taste specialtiesAnd (A and B ) .proves taste between these three specialty is significantfive cheese specialties