The importance of solids
Non-fat milk solids basically consist of proteins, lactose and mineral salts. Milk proteins facilitate the incorporation of air bubbles in the ice cream mixture and act as a thickening agent.
Fresh milk contains about 9% non-fat milk solids, which is the sum of the proteins (3.5%), lactose (4.5%) and mineral salts (1%) in it. Skimmed milk powder on the other hand contains no less than 95% non-fat milk solids, half of which is lactose. An ice cream mixture ideally contains a total of 7-12% non-fat milk solids.
‘Other solids’ is a term used to describe all the components in your ice cream mixture that are not sugars, fats, non-fat milk solids or water. It comprises all stabilisers, emulsifiers, thickening agents, cocoa solids, fruit, hazelnut paste etc. In other words: all fibres.