Preparation of Ingredients before Mixing

Ingredients that should be dispersed before mixing commences

Most factories operate a partial bulk handling system for their ingredients. The reason for this is that it is cost effective to bulk handle the large ingredients but relatively expensive to mechanise the metering of the small ingredients which often require special attention before they are added to the mixer.

During mixing there is usually good dispersion of even the smallest ingredients. However there are certain ingredients that tend to lump either during storage or when mixed in a dough. If these lumps remain, biscuits may show black spots or have uneven structure after baking.

It is advisable to sieve sodium bicarbonate before use, to dissolve ammonium bicarbonate and to disperse milk and whey powders in water with a high sheer action.

Sodium metabisulphite (SMS) is normally used as a 10% solution to aid metering of the very small quantities used.

Emulsifiers, like lecithin, work most effectively if they are well dispersed in the fat before an emulsion with water is made. If blocks of fat and emulsifier are used for a mixing, it is worth considering making a preliminary mixing of the fat, emulsifier and possibly the sugar, before the other ingredients are added.

Fresh yeast should be dispersed in some water and when adding to the mix care should be taken to avoid putting the suspension near to the salt or other chemicals as these may kill the yeast cells.

Proteinase enzyme, as may be used in savoury cracker doughs, must be handled with care especially if it is a powder. Place the enzyme into the mixer so that there is no splashing or dust. The dust may cause irritation and damage if inhaled.

Dough fat should be plasticised before use. If it is purchased as warm oil in bulk it must be cooled and plasticised as has been described in the section on Ingredients. Dough fat and butter purchased in blocks has been plasticised but must be brought to a suitable temperature (about 18°C) before being added to a mix to ensure that good dispersion occurs during the mixing.

Dried fruit such as currants are usually purchased as blocks in boxes. It is necessary to break up these blocks before use and the best way is to use a fruit washing machine. This machine not only breaks the blocks of fruit but also gives a very quick washing (allowing only a minimal absorption of water on to the fruit). The washed fruit is then in a state where inspection can remove any stalks or stones that may have been left in the fruit.

In some cases the fruit is soaked in warm glycerine. Absorption of glycerine reduces the chance of the fruit becoming hard and leathery during baking.

Desiccated coconut is rarely fine enough to be added as such to a dough. It is best to mill this material into a "flour" soon before adding to a mixer. Coconut that is bought as coconut flour tends to be very lumpy because the coconut oil sets at normal ambient temperatures. If the "flour" is warmed the lumps become softer and should disperse during mixing.

Biscuit recycle must be milled into a fine crumb or dispersed in water before use.