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Results

Boil The teacher joined themilk of the groups andboiled it, and then it wasdistributed equivalently,the milk was really hot,and it still white.

Stir/blow We waited, stir and blewthe milk until it had aslightly warmtemperature in which

when inserted the fingerit wouldn’t be burned,after we skimmed themilk because of the skinthat was formed.

Yogurt We added yogurt to themilk and mix it, as wemixed it changes itstexture and color, now itis tangy and pink.

Cover We covered the jar withnewspaper and vinipelso no air will enter and itwill stay warm.

Blanket We covered the jar witha blanket so it will stay inwarm temperature.

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Sun We leave it in a placewere no sunlight couldreach it.

Curd Mix the curd with awooden spoon, so thatno curd would stay.

Sugar We added some sugar to

give the yogurt a bettertaste.

Refrigerator We put the yogurt in thefridge so that it will staycold and likewise ispreserved.

Data analysis

Boil The milk was boiled to kill all thebacteriathat are able to live in it, with thiswe can assure that the only bacteria that

stay alive are the ones that we are goingto introduce in the yogurt. We don’t boilthe yogurt as well because that wouldkill the bacteria that are in charge ofcreating the new yogurt.

Stir/blow We wait, stir and blow the milk, with thiswe want to get the yogurt to atemperature in which the bacteria that

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live in it will be able to stay alive.

Yogurt Bacteria need to be warm and nutrientsto grow and reproduce; the bacteriagrow and transform the milk into yogurt.

Cover/Blanket We covered the jar so no more bacteria

will be allowed to enter the yogurt. And itwill keep a warm temperature.

Sun We can’t put it in the sun because thesunlight will change the temperature andit may kill the bacteria in the yogurt.

Curd We mix the curd so the yogurt will be ahomogeneous mixture. That mixture ispink has a thick, creamy tangyconsistency and smells a little bit bad.

Sugar The sugar is added to the yogurt so itwill get a sweet flavor.

Refrigerator The yogurt is introduced in therefrigerator so it will be conserved for alonger time. The yogurt needs to have atight cover on the container to keep thebacteria that are good inside so it wouldbring benefits to your body.

[Enlínea] tulinea.es/útil/art/index_art.aspx?art_id=864992&sc=3021, recuperado:

November 2 de 2013

[En línea] experimentar.gof.an/nota.php?id_nota=bacteriasExpcion, recuperado:

November 2 de 2013

Observation:

The yogurt turns its color from White to pink, its texture change into tangy and

tastes bad.

The Lac Operon

We can deduce that in the container the bacteria is growing and reproducing while

the lactose is being consumed, this means that the repressor in the Lac Operon is

off the structure so it isstopping the production of milk.

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Conclusions

The yogurt is produced when two kind of bacteria are mixed with the milk, this

bacteria eats the natural sugar in the milk called lactose.

The assimilation of the sugars inside of the bacteria produces an acid lactic that

makes the sugar’s bacteria to form a curd. The effects of this coagulation are an

acid flavor and a creamy composition.

Questions

1. What is pasteurization?

Pasteurization is a process of heating liquids to a specific temperature to killmicroorganisms that can cause disease [En línea]http://infectiousdiseases.about.com/od/prevention/a/pasteurization.htm, UpdatedJanuary 16; 2009 o rev. November 2, 2013

2. Compare your “home-made” yogurt to the “store-bought” variety. What effect

do some of the other ingredients have on the “store-bought” yogurt? 

The home-made yogurt obtains its color from the fruit you added to it, also it

doesn’thavepreservatives, and it doesn’t have sugar. 

Instead the store-bought yogurt has artificial colors for give the appearance that it

has a lot of fruit, also it contains preservatives to increase unopened shelf life, and

it contains sugar in order to remove a little bit the tangy taste. [En línea]

http://wilsonproces.blogspot.com/2012/10/normal-0-21-false-false-false-es-ec-

x.htmlmates, 23 De Octubre de 2012.

3. What are the 2 most common bacteria used in yogurt making? Which one did

you use?

The most common bacteria used in yogurt are Lactobacillus Bulcaricus and

Strepctococcus Thermophilus. We used both of these bacteria because from theLactobacillus Bulcaricus we got the acid flavor and from the StrepctococcusThermophilus we got the creamy composition. [En linea]experimentar.gof.an/nota.php?id_nota=bacteriasExpcion, recuperado: November 2de 2013