Ice Cream Making

Question 1

What did we do in this practical?

Answer 1

We made ice cream using whipped cream, milk, sugar and egg yolk. We used liquid nitrogen as a cooling agent.

Question 2

What is ice cream?

Answer 2

It is a frozen mixture of milk, cream and sugar incorporated with air.
The texture depends on how fast the ice cream is frozen. Fast freezing lead to smaller ice crystals and smooth texture. Slow freezing leads to bigger ice crystals and a coarse texture.
The role of liquid nitrogen is to achieve quick freezing.

Question 3

Describe food stabilizers

Answer 3

They are usually polysaccharide food gums, that are responsible for adding viscosity to the mix and unfrozen phase of ice cream.
They keep the form of food and prevent change in chemical composition.
They are ingredients that simply thicken water,

Question 4

What are the 3 functions of food stabilizers in ice cream?

Answer 4

They keep ice cream smooth by reducing rate of water migration and growth of existing ice crystals
They reduce air bubble size
They slowdown the rate of melting
They increase body and creaminess
They deliver flavor cleanly

Question 5

Explain how food stabilizers exert their functions in ice cream

Answer 5

1) By restricting the free movement of water, stabilizers prevent melted ice crystals from finding and joining existing ice crystals when they re-freeze.
2) Greater shear force that’s applied to more viscous liquids when they are being churned in the ice cream maker, reduces the size of the bubbles more.
3) Water binding qualities of stabilizers: viscous mixtures simply melt slower.
4) They also add body and give a creamy mouth-feel and a silky finish due to added viscosity and less free-flowing water.
5)

Question 6

Fun quiz what is a gel?

Answer 6

Gel are substances that exhibit the characteristics of both a liquid and a solid. Food technologists define a gel as a high moisture food that roughly retains its shape when released from its container

Question 7

Explain if coconut milk is suitable to be replaced with dairy milk in ice cream processing.

Answer 7

Yes, can be used. High in fat content and protein structure similar to milk proteins that act as emulsifier.

Its high fat content allow it to mimic the consistency and thick viscosity of dairy fat and trap air similar to dairy fats

Question 8

What if freezing is slow instead of using liquid nitrogen?

Answer 8

Grainy and coarse crystals, the slow freezing lead to bigger ice crystals

Question 9

If you have to depress the freezing pint of ice cream for it to be stored under summer conditions, which ingredient in the ice cream formulation should be worked on?

Answer 9

Add more salt and sugar. Adding them can depress the freezing point. In summer ice cream has to be stored at a much lower temperature so that there is a longer time between water reaching freezing point and melting point to delay melting for better consumer experience.

Question 10

Describe the 5 roles of emulsifiers

Answer 10

They are chemicals with a hydrophobic end and hydrophilic end.

1. Egg yolk lecithin firm up the ice cream emulsion by reducing oil and water separation
2. They stabilize the ice cream by binding to water and inhibit thawing, thus extending product shelf life
3. Egg yolk lecithin add flavor and richness to the ice cream, give it a custard-like flavor
4. They add a subtle yellow color to the ice cream
5. They add density, creates smoother texture and better mouthfeel.