Dough Mixing as Important Part of Production Process

CLASSIFICATION OF BISCUITS BY ENRICHMENT AND SHAPING

Hard (Semi-Sweet) Dough: Reciprocating Cut; Embossed and Rotary Cut. Usually low in combined fat and sugar content and high in water addition at the dough stage. Also referred to as semi-sweet biscuits. The water content is much lower than for lean types, but the dough is mixed for a longer period to develop the gluten and work it to a state of maximum extensibility.
Examples: Petit Beurre; Marie

Lean Dough: Reciprocating Cut; Embossed and Rotary Cut. Contains virtually no sugar and very little fat.
Examples: Water Biscuits

Puff Biscuits: Reciprocating Cut; Embossed and Cut. Puff Biscuits have very low sugar content, but a relatively high fat content.
Examples: Butter Puff; Cornish Wafers

Soft Dough: Rotary Cut; Rotary Moulded. Normally high in combined fat and sugar content with a low water addition.
Examples: Lincoln; Custard Creams

Short Dough: Rotary Cut; Rotary Moulded. Short dough contains a high percentage of fat and sugar.
Examples: Shortbread and Shortcake

Medium Short Dough: Rotary Cut; Rotary Moulded. A medium short dough, contains a lower percentage of combined fat and sugar.
Examples: Digestive, Abernethy

Flow Biscuits: Wire-Cut; Extruded. Flow biscuits are high in combined fat and sugar, but in contrast to the short dough types the sugar greatly exceeds the fat content.
Examples: Cookies; Sprits

Batter Biscuits: Deposited. Batter biscuits can all be deposited and are relatively high in water content.
Examples: Barmouth; Bordeaux; Viennese

THE MIXING PROCESS

Basically, the main ingredient of dough is wheat flour and although flour at first seems to be a simple material, about 75% of it is starch; it contains a somewhat complex form of protein material known as gluten. It is this protein matter which forms the structure in all bakery goods during the dough-making process and it plays a vital role in the appearance, structure and texture of the finished product.

During the mixing process, we have to attempt to utilise the structure forming properties of gluten to the full, but, at the same time, we have to overcome an undesirable toughening tendency to which gluten i.e. susceptible. Shortening, sugars, syrups and various other ingredients can physically and chemically alter the properties of gluten by delaying or neutralising its toughening effect.

Mechanical action can also physically produce changes in the protein of flour and, in dough where the amounts of shortening, sugars or other ingredients that would have had the same affect are purposely limited, then mechanical working can break dough the toughening characteristics: of the gluten whilst taking full advantage of its structural forming capability.

This is one of the reasons why Semi-Sweet dough takes so much longer to mix than Short dough. The object of mixing is of course to incorporate thoroughly all the ingredients which are being used, so that it is homogenous.

Dough mixing is an extremely important part of the production process. The recipe and mixing method are aimed to produce a finished biscuit of the correct quality and dimension. Process specifications are established as an aid to achieving and maintaining consistency.

The main features in dough mixing are:
a) the preparation before mixing, ensuring that all the ingredients for the mix is dispensed in the correct quantities
b) the sequence of dispensing the ingredients into the mixer
c) the ingredient water content
d) the mixing method to be adopted

Whether the degree of mixing required is determined by the number of revolutions of the beaters (paddles), or time or final dough temperature, a satisfactory technique once established must be closely adhered to so that consistent results shall be maintained.

Dough for rotary moulded cookies must have this consistency (rather than crumbly) that it will compress uniformly into a coherent biscuit shape in the engravings of the die mould, and will adhere sufficiently to the extraction web so that it is extracted cleanly from the mould for transfer to the oven band without breaking up before or after baking. The recipe and mixing method are aimed to produce a finished biscuit of the specified quality and dimension.

Water jacket temperature: Dependent on climatic conditions, the ‘tempering’ of circulating water in the jacket, is claimed to control the dough temperature, however in my experience in warm climates, as the flour temperature is relatively high, there is little evidence of its effect, due to the small surface area of the water jacket surface area in contact with the dough, and therefore manufacturers revert to replacing some of the ingredient water with ice. In warm climates, carbon dioxide is pumped into the mixer of short dough during the mixing cycle, when chocolate chips have been added, to prevent them melting.

ROTARY MOULDING DOUGH
Rotary moulded dough are generally fairly high in sugar and shortening and low in moisture, as mentioned before, gluten development should definitely be avoided. In general the ‘two-stage or ‘three-stage’ mixing procedure is used for rotary moulded dough, (short and soft dough).

Stage one must achieve a well-creamed mass, irrespective of the mixer, speed or time required. With a horizontal two-speed mixer running at top speed, 3–5 minutes is usually sufficient time for mixing, other slower speed mixers would require longer times.

In stage two, the incorporation of the flour requires mixing in slow speed, which will disperse it uniformly, but the dough must not be over-mixed to avoid toughening of the dough (gluten development).

ROTARY CUTTING MACHINE DOUGH

The mixing of this type of dough can be accomplished by the ‘all-in-one’ or ‘one-stage’ mixing, by placing all the ingredients in the mixer commencing with the solids and following with the syrups, liquids etc and mixing the mass thoroughly and until a smooth dough is obtained.

Where the ‘two-stage’ dough mixing is employed, all the ingredients including water (except flour and aerating chemicals) are mixed to form a ‘cream-up on high speed for 5–8 minutes. This is followed by the addition of flour and sodium bicarbonate (sieved) and ammonium bicarbonate added in solution, and mixed on slow speed until dough is formed.

In the ‘three-stage’ method, sugar and syrups, shortening, salt, essence, milk powder and the water (a small quantity should be held in reserve to dissolve the ammonium bicarbonate) are creamed until a smooth cream is obtained. Salt, flavours and the remainder of the water (with ammonium bicarbonate in solution) are mixed to maintain a smooth cream.
Finally, flour and sodium bicarbonate (sieved) are added and mixed to a desired dough consistency, to ensure uniform distribution of all ingredients, but not over-mixed to the point of toughening the dough.

WIRE CUT AND DEPOSIT TYPE DOUGH
Batch size, mixer capacity, and mixing time and process throughput in the forming section and baking are very closely interrelated in the case of wire cut products.

These types of dough are prepared using the two-stage or three-stage mixing technique on high or low speed mixers. This will hold the water in a more or less stable state, so that it is prevented from being absorbed by the flour and developing the gluten.

RISK ANALYSIS REVIEW

Critical parameters
Ingredient holding time prior to mixing and its effect on the hydration of flour, sugar etc and fat crystallisation. Sequence of adding ingredients to prevent interaction. e.g. Invert Syrup and sodium bicarbonate. Beginning and end of mix syndrome: variation in dough consistency, is often due to insufficient dough standing time (lay time) after mixing.

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