Science Badge Question 7

How does milk become yogurt 

Hypothesis> I think milk becomes yogurt because milk thickens if you add cream and mix it up then add fruit then put in the freezer. 

Materials> Milk,Yogurt (fresh plain)

Method> In a beaker add 150mls of trim milk and 2tsps of Acidophilus  yogurt.stir to mix. leave out over night.Repeat this for the cream and with trim(milk)

observation 
trim-When I looked at the trimed milk it looked normal it looked like milk ,With bubbles 
cream- When I looked at the cream Ihad a hard look at it and it was a light yellow 
blue- When I looked at the blue milk it looked flat ,No bubbles or anything

At what temp does bacteria?
What temp is a fridge?
What is the healthy temp of a human? 

The cream one looks like this 
The cream smells gross

The blue looks like this 

It smells like milk

And the trim looks like this 

It smells like yogurt 

What happened to change it 

The bacteria reproduced 

The bacteria fed off the sugar in the milk
The trim milk made a thinner type of yogurt than the others because it has less sugar. 

We let the milk stay out for 2 days and then placed the the beakers in the fridge. The results were not very good but it could change. 

If we got to do it again I would leave the milk in the fridge for longer.