unsure

variation

4s

smoked

pseudo choc

depressed

we know that when frozen desserts have too much sugar they will not freeze, or should I say they never get hard… or maybe they don’t freeze…. or are they frozen but still fluid?  this subject can get boring fast so we will by-pass the extra words and cut to the facts.

what does sugar do in frozen desserts?

1. flavor
2. texture

flavor

-          sugar makes desserts sweet – duh….  but not all sugars have the same level of sweetness

-          different sugar give different flavors – brown, demerara, turbinado, muscovado, palm, molasses, treacle, honey – …duh… again….  but all these sugars contain different (not just flavor) amounts of solids and water… remember those?!?!

texture

-          more sugar = softer texture.  when sugar is dissolved in water it lowers the freezing point of the solution.

• water freezes at 0C
• when water is added to sugar you have a syrup – a solution in which sugar has been dissolved in water

lets build on that idea a little.  sugar loves water and very easily absorbs it (meaning it is hydroscopic).  a piece, or molecule, of sugar can only absorb a certain/finite amount of water.  once our sugar has absorbed its water,  what about the remaining water…  it stays as just that, water (this is also known as free water).  you now have a solution that has water and water that is attached to sugar.  going back a step water freezes at 0C, so,  the free water freezes at 0C… the water that has bonded with the sugar freezes at a temperature below 0C.  this is the basics of freezing point depression.

• as the amount of sugar is increased, the amount of free water (that freezes at 0C) decreases
• more sugar and less free water = lower freezing point

not all sugars are created equal.  if we compare all of the sugars available to us you will see that when tasted they all have different levels of sweetness.  most sugars are a combination of fructose, glucose and maltose.  the molecules are arranged in different way to create different levels of sweetness. this level of sweetness is called it sweetening power.  sweetening power is measured in percentages and sucrose is what all other sugars are compared to.

-          sucrose = 100%, honey = `125%, dextrose = 75%

if you have 100g of sugar you can manipulate how sweet it is by using the different varieties available to you.  100g may harden at the perfect texture in your freezer but taste to sweet.  if that is the case you can keep the same amount of sugar but use a different sweetener to make it taste less sweet.

1. If I go into any more depth we will be here all day but I want to touch on two more things very briefly.

corn syrup/liquid glucose/powder glucose/dextrose

this can hopefully shed some light on the question “why do we use powder glucose?”

all four of the sugars mentioned above are derived from starch (most commonly corn starch).  starch is “mixed” with water and acid (hydrolysis) to obtain glucose….  but it is not quite that simple.  starch is made from long chains of glucose molecules that are linked together.  hydrolysis breaks down these chains to leave us with pure glucose.  all four of these sugars represent a different stage/level of hydrolysis.

• starch = full chains before hydrolysis
• glucose syrup = partial hydrolysis,  the chains are broken down to varying degrees.  the more the chains are broken down the sweeter the syrup.  the amount  the starch has been broken down is referred to as DE, or dextrose equivalent.  the lower the number the less bonds have been broken resulting in a less sweet syrup.  the glucose syrup we use is 42DE.  (100DE = dextrose)
• corn syrup = partial hydrolysis, the chains have been broken down the same as for glucose but then sucrose and fructose are added to give a liquid sugar with a high sweetening power

1. syrup and powder can be used interchangeably however they must be the same DE and the difference in water must be accounted for to achieve the same results.

• dextrose =  full hydrolysis.  the chains have been completely broken down.  this is glucose is it pure form, 100DE.

reminder:   liquid sugars vs. dry sugars

• dry sugars (sugar in powder form) will absorb water
• liquid sugars (sugar in a fluid form) will add water

this must be taken into consideration when balancing solids and water

download sweetening-power

Tags: frozen desserts, ice cream, science, sorbet, sugar, writing recipes