The science behind ice cream making.

2.  Ice cream is a colloid, a type of emulsion. An emulsion is a combination of two
substances that don't normally mix together. Instead, one of the substances is
dispersed throughout the other.
 In ice cream, molecules of fat are suspended in a water-sugar-ice structure along with
air bubbles.
 The presence of air means that ice cream is also technically a foam.

3.  Frozen dessert usually flavoured with fruit, made from water, sugar, flavourings, and
milk or cream.
 Egg white or gelatin may be added to ensure a fine texture.

4.  Colligative property
 Freezing mixture
 Ice crystals
 Interfering substance
 Milk fat or butter fat
 Milk solids
 Non-fat solids
 Nucleation
 nuclei
 Overrun
 Rate of freezing
 Stabilizer
 Viscosity

5.  To identify the water content of ice
cream and sherbet mixtures and relate
this to freezing rate
 To understand the effect of sugar
concentration on the depression
freezing point of water in ice cream
and sherbets.
 To understand the effect of a mixture
of salt and ice which surrounds a
container of mixtures of ice cream and
sherbets in the freezing process.
 To appreciate the significance of
agitation during freezing, its effect on
the structure of the frozen mixture, and
overrun and its role in breaking up
large ice crystals to form a smooth-
textured product.
 To appreciate the significance of
stabilizers in maintaining the size of
crystals and the firm body of the frozen
product.

7.  Influence the freezing temperature of water.
 Addition of a non-volatile solute like salt and sugar the freezing point drops in
proportion to the amount of dissolved substances and for an ionisable one, in
proportion to the dissociated ions.

9.  Created when the water-content in the
base starts to freeze
 Gives solidity and body.
 The size of the ice crystals largely
determines how fine, or grainy, the ice
cream eventually turns out.
 The main objective (apart from the
freezing itself) is therefore to keep the
size of the ice crystals down as much
as possible.

10.  Often in the form of butter (milk) fat.
 Adds richness, stabilises the base mix, improves density and the smoothness of
texture and generally increase flavours

11.  Sugars, honey or syrups
 Adds sweetness but also
improves texture and body.
 Lowers the freezing point of the
mix, ensuring that the ice cream
does not freeze rock-solid

12.  The invisible (and cheapest) ingredient in ice cream.
 The tiny air cells whipped into the base mix are largely responsible for the general
consistency of ice cream, and greatly affect texture and volume.
 “Over-run” is the technical term used to indicate how much air an ice cream holds;
since air is free and increase the volume, non-premium commercial ice creams could
well have an overrun sometimes even exceeding 100 %.

13.  Usually so-called non-fat milk solids, such as proteins and mineral
salts, and flavourings such as cookie-crumbles.
 Contribute to the body, texture and smoothness.
 More solids means less “free-roaming” water in the ice cream – which in turn usually
means less unwanted, large ice crystals in the ice cream.
 Too little solids, the ice cream often tends to become unpleasantly icy.
 Too much solids, however, may bring about an unpleasantly sandy-like sensation.

14.  added to the ice cream base – one or more ingredients that help the other “unwilling”
ingredients to combine.
 Egg yolk

15.  Improve the structure and texture by keeping down the growth-rate of the ice crystals
of the ice cream
 Reduce the melt-down speed of the ice cream.
 Gelatin, egg whites

17. A well frozen appearance
Absence of large ice particles
A pleasing blend of banana with lemon or lime rind, a subtle
acid taste which complements the bland banana flavor

18.  Introduction to Food Preparation by Guzman, M.P. and Fojas de Luna, M.V.
 http://www.icecreamnation.org
 Chemisrty: The Central Science by Brown and Le May