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Chemistry > Chocolate > Flashcards

Flashcards in Chocolate Deck (21)
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1
Q

How is chocolate made?

A

Dried fermented beans are roasted ar 110-140 degrees for 46-60 minutes.
Roasted beans are either pressed into cocoa butter and powder or ground to make cocoa solids.
Cocoa solids are conched for 3-4 days and ground with sugar with heat to remove volatiles.
Extra cocoa butter is added to coat the cocoal solids and sugar to make chocolate liqour.

2
Q

descirbe the process of conching and what does it produce.

A

Sugar cyrstals + cocoa milk and molten cocoa butter and leathin

These are conched at 54 degrees for 72 - 96 hours
This produces a stable dispersion of chocolate liquour.

3
Q

How does the size of the solid partcles affect the sensory feel of chocolate

A

If particles are too large (>30 nanometres) chocolate feels gritty.

Smaller particles make chocolate more viscous and smoother

4
Q

what is the preferred size of chocolate in the UK and Europe

A

In the UK 15-25 nanometers

In europe 2 nanometers

5
Q

what determines the size of the chocolate

A

The time spent conching, longer periods means smaller particles but longer conching periods means it is more expensive

6
Q

What does X ray diffraction show about the structure of chocolate

A

It is a polymorphic structure with 6 cyrstalline structures

7
Q

Descirbe the change in properties as you go from phase 1 -6

A

melting point and stability increase and density increases due to more compact chain packing

8
Q

Which phases are used for chocolate

A

Phases 5 and 6 as MP is closest to body temp so chcocolate melts in the mouth.

9
Q

What does temepering involve

A

slowly heating chocolate to 44 degrees and then slowly cooling it to 31 degrees. This allows chocolate to crystallise into phases 5 and 6 exclusively

10
Q

How much theobromine is present in chocolate

A

1.5 - 2.7%

11
Q

How does theobromine affect the body

A

It is a weak CNS stimulant. Its is a diuretic, cardiac stimulant and causes dilation of arteries and viens. The effects are short lived as it has a half life of 6 - 10 hrs

12
Q

How much caffiene is in chocolate and descirbe the effects of caffiene on people.

A

About 0.1%. It is a stimulant for the heart and CNS. It promotes wakefullness. Is also a diuretic which caused heachaches and constricts blood vessels.

13
Q

What are polyphenols and what benefit do they have

A

Anti oxidant - reacts with free radicals to reduce oxidative stress in the body. Prevents the oxidation of LD lipids with will otherwise block arteries.

14
Q

What other function do polyphenols have in chocolate

A

They prevent it turning rancid and act as a preservative

15
Q

What is the Maillard reaction

A

Complex set of reactions that occur on heating sugars with amino acids to produce a brown N based polymer called Melanoidins, Converts flavourless amino acids to aldehydes

16
Q

What is meant by chocolate is a shear thinning non newtonian fluid

A

The viscosity of chocolate depends on stirring rate. So the harder chcoclate is stirred the easier stirring becomes as viscosity has increased.

17
Q

What does chocolate liquour viscosity determine

A

Coating thickness.

18
Q

What is chocolate blooming

A

When chocolate developes a white powdery surface due to sugar or fat bloom

19
Q

What is sugar blooming

A

occurs when sugar dissolves in surface mixture and recyrstallises. It is irreversible.

20
Q

What is fat blooming

A

cocoa butter doesn`t undergo phase transition. Choco feels oily and greasy. Reversed by storing in cool conditions.

21
Q
A