Tstl Mathieu G S Pta

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_The goat cheese__



First of all we chose the topic of goat cheese, because this is a food like cheese that is very consumed by the French and that affects us all . so we wanted to study this subject and which made us want to discover it and to learn more about this product these well done but also these disadvantages and how this product is manufactured , with that it raw material , and if different raw material are used which are the healthiest used.



First of all we contacted an artisan cheese maker who makes goat cheese exclusively with raw goat’s milk.
Ask about making cheese about the well-made raw milk cheese and the difference between raw and pasteurized milk (use in industrial cheeses, or other artisan ) the one that we are told has the opposite that most people believe is that raw milk cheese has done much better than pasteurized milk cheese , he even explained to us that pasteurized milk was a denatured milk that we were removing the true nutritional value of product and that gives birth when the raw milk is handled with a hygiene respect the raw milk cannot make sick and even would protect us and protect the newborn from the diseases and bacteria that surround us but that the pasteurized milk will bring intolerance that encounters our society today .
In addition to asking this craftsman questions, we carried out research to compare these words, so we saw that it was not the only one criticized the pasteurizing milk cheese we ended up wanting to experiment our research to help prove what we explained to us the cheese maker we questioned,and we concluded that our problem was “Do you better make goat cheese with raw goat milk or pasteurized goat milk?”
But before manipulating and experimenting, we ask questions about the molecular, bacterial and quality point of view (taste and visual) between two cheeses a first artisanal cheese made by the artisan we met and between an industrial cheese in large area (made from pasteurized milk ).

Our questions are:

1-We then wondered if raw milk cheese after processing contained more lactic bacteria than in pasteurized milk cheese?
2-Then it was asked if this artisanal raw milk cheese could have possessed the harmful bacteria and for some deadly «Listerria» compare to pasteurized milk cheese?
3-After we know whether calcium was more present in raw milk cheese than in pasteurized industrial milk cheese?
4-Finally, we were wondering if there was a big difference between the two cheeses in terms of taste and visual and even smell?

Our assumptions and experiences:


After we asked ourselves these questions we therefore made a hypothesis and experiment to confirm and answer our questions:
-The first assumption was that “there was more lactic bacteria present in raw milk cheese than in pasteurized milk cheese.” The lactic bacterium was then counted to prove this hypothesis:

-solution of raw milk cheese and pasteurized milk cheese prepared with a stomacher
-1ml graduated pipette
-MRS media agar box
-anaerobic jar

1) preparation of the stock suspension with the help of the stomacher, place them in test tubes.
2) dilute 1/10th up to 10-8 using 1mL graduated pipettes in the test tubes of each dilution with each SM (pasteurize cheese and raw milk cheese)
3) seeding on MRS medium from all dilution of the two stock suspension be a V(inoculum) = 1 ml to be put in 16 identical petrie boxes in sterile zone. Be 1 box per dilution.
4) incubate the boxes in an anaerobic jar at 37°C for 24 hours


-Another assumption was made that “raw milk cheese and pasteurized lais cheese did not both contain Listeria bacteria”, so a Listeria count was performed:



-ALOA medium agar box
-1 ml graduated pipettes
-metallic ose
-solution of raw milk and pasteurized milk cheese


1)pre-enrichment on Fraser medium for 48h at 30°C with a 1 ml graduated pipette taken a volume of 1ml for each mother suspension pre-enriched a medium with a raw milk cheese suspension, a second pasteurized milk cheese medium.
- 2)enrichment on medium fraser 48h at 30°C same volume as pre-enrichment and two enrichment taken from pre-enrichment one for each stock solution (raw milk cheese and pasteurized milk cheese).
-3)Sown on medium Aloa at 30°C for 72 hours with a metallic ose sample from the enrichments of the two stock suspension. Isolation in 3 zones,sterilization between each spreading of each zone.

-A third assumption was made that “raw milk cheese has a higher concentration of calcium than pasteurized milk cheese”, so a calcium determination was made for both cheeses:

-graduated pipettes 1ml
-5ml graduated pipette
-mechanical pipette with 10 microliter connection
Calcium kit solution A and B
-Ca2+ standard solution
-solution of raw milk and pasteurized milk cheese


-1)it is first necessary to mix a solution A/B for a total solution of a volume of 7 ml be 3,5ml of solution A and 3,5ml of solution B
-2)6 vessels must then be taken for spectrophotometer analysis
-3) be with a white tank with 1 ml of mixture A/B and finally 20 microliters of distilled water then prepare a standard tank with 1 ml of mixture A/B and 20 microliters of a standard solution Ca2+ finally prepare two tanks of raw milk cheese be with 1ml of mix A/B and 20 microliter of raw milk cheese solution pressed to the stomacher the same thing is done with pasteurized milk cheese solution .
-4)Finally we wait 2 minutes and homogenise, we finally read the absorbance and calculate the concentration of the tests .


-A final hypothesis: «raw milk cheese has a higher taste quality and the smell and appearance is more beautiful than pasteurized milk cheese», so we make a tasting:

-1) the cheese is cut and compared, people are asked to taste it voluntarily and their opinion on the taste, the visual and finally their preference is sought.


Our results and problem encountered during the project:

Our results for the first experiment on lactic bacteria:

Raw milk cheese did have a higher count of bacteria than pasteurized milk cheese . it was concluded that raw milk cheese does indeed have a high concentration of commensal flora bacteria that is good for the body compared to pasteurized milk cheese. For this experience we faced no problem.

Results on the enumeration of Listeria:

The two cheeses tested did not have any Listeria. It was therefore concluded that raw milk cheese is no more likely to be contaminated by Listeria than pasteurized milk cheese. We had a lot of trouble analyzing this bacterium because the experiments we did were new experiments and so it took us longer to do it.

Results for calcium determination:

Raw milk cheese has a higher calcium concentration than pasteurized milk cheese. We therefore concluded that you eat raw milk cheese better than pasteurized milk cheese to want to have more calcium for our body because raw milk cheese has a high concentration of calcium. We encountered difficulties during this experiment because first we could not find consistent and conclusive results because our technique was not high enough but we had succeeded in the final after several tries.

The results of the tasting:

A larger number of people who had preferred raw handcrafted milk cheese over a dozen people only preferred industrial cheese were the people who found that the taste of raw milk cheese was more pronounced than its texture was pleasant and melted everything what we’re looking for on fresh goat cheese,but that the smell was stronger whereas on the contrary people described industrial pasteurized milk cheese as less melting plaster, more elastic with less taste and a less strong smell . It was therefore concluded that the quality of an artisanal raw milk cheese was more important and pleasant to eat than an industrial pasteurized milk cheese. No difficulties encountered during this experiment.

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