mixing process tends to be used which also encourages gluten forma-tion. Modification of the dough rheological character may also be un-dertaken through the addition of a reducing agent, commonly sodium metabisulphite (SMS), or a suitable proteolytic enzyme. If it is not pos-sible to modify the dough rheological properties through the addition of a reducing agent, extra water may be used to give a softer, more machinable dough.
The important effects on biscuit processing which arise from varying added water levels have been studied by a number of workers. Gaines (1982) evaluated the consistency and stickiness of sugar-snap cookie doughs made with four different water levels. His data suggested a two-phase (initial and time-dependent) requirement for water by flour and sugar. In freshly mixed doughs, variations in water levels had ap-proximately equal effects on dough consistency and stickiness, while in doughs that had been rested for 1 h, changes in the water level had twice the effect on dough consistency as on dough stickiness.
The control of temperature in the manufacture of
Calculating the water temperature to use in the manufacture of biscuit and cookie doughs is more complicated than that for the bread dough or cake batter. One complicating factor is associated with the use of a cooling jacket on the mixer since the heat carried away by the refrigerant needs to be taken into account. Probably the best way to establish the full relationship is to carry out a few trial mixings and record all the ingredient starting temperatures and the final dough temperatures to establish an ‘average’ heat loss for the effect of the cooling jacket.
Formation and processing of short pastry doughs
Short-dough pastes are used in a variety of bakery applications and products. The main forms can be classified according to whether they are used for the production of sweet or savoury products and are most commonly determined by whether sugar is present in the paste formu-lation (Cauvain and Young, 2006). Examples of sweetened short-paste products include the various forms of filled fruit pies, while savoury pastries are most often associated with various meat and vegetable fill-ings. Savoury pastry forms are less common than the sweet type and are mainly used in the manufacture of British and Australian pie products.
Once baked, the pie products made from savoury pastries may be eaten warm or cold, depending on the type and consumer preference.
Gluten formation in short-pastry doughs is not normally required, and if it occurs may lead to problems during processing and baking.
The main problem will be related to shrinkage of the paste after forming (blocking) and during baking. Once again added water levels must be kept to a minimum because much of the water is baked out in the oven to give a crisp eating character to the pastry. Maintaining pastry crispness in cold-eating types is a particular problem in this group of products because of moisture migration between the components (see Chapter 7).
Mixing methods for short-pastes may be all-in or multistage. As is the case with short-dough biscuit pastes the multistage methods aim to limit gluten formation. The three multistage methods in common use for short-pastry production are
r
Rubbing-in, in which the flour and the fat are first mixed together before the addition of the water and soluble materials.r
Creaming, in which only half of the fat and the flour are mixed together, followed by the addition of the remaining fat, water and soluble ma-terials (e.g. salt and sugars).r
Boiling water, in which the water (and sometimes the fat) is heated before being mixed with the other ingredients. This method is used only in the production of savoury pastes.Figure 3.6 Effect of the water level on short-paste resistance to deformation.
(Based on Hodge and James, 1981.)
Taylor (1984) compared the all-in, rubbing-in and creaming mixing methods for short-pastry production and concluded that they had little effect on the handling properties of the paste or the final baked pastry.
Such conclusions suggest that the concept of ‘waterproofing’ flour to prevent gluten formation has little credibility and it is more likely that the smearing of fat throughout the flour acts as points of discontinuity and weakness in the gluten network formed during mixing.
Cold water short-pastes are sensitive to the level of water used in the recipe. Hodge and James (1981) studied the effects on paste rheological properties of varying recipe water levels from 10 to 20% flour weight (the flour had 14% moisture) in 1% incremental steps. Using a form of penetrometer they showed that paste resistance to penetration gradually fell as the water level increased, reached a minimum at about 15% and then increased as recipe water levels continued to increase (see Fig. 3.6).
It would appear from the data recorded in Fig. 3.6 that the development of a continuous gluten network did not occur until the added water level exceeded 15% of the flour weight.
In the production of savoury short-pastes for pork pies, Mears and Wade (1969) concluded the properties of the paste did not appear to be particularly sensitive to variations in added water content, although the final paste temperature did vary with variations in added water temperatures, as would be expected. The same authors concluded that the temperature of the water at the time of addition to the other recipe ingredients during mixing also had little effect on paste properties.
Formation and processing of laminated doughs
One special group of bakery pastry products is characterised by the formation of alternating and largely discrete layers of doughs and fat (Cauvain, 1995). Because of the sheeting and folding processes used to achieve these structures the products are known collectively as ‘lami-nated products’ and they include both unyeasted and yeasted varieties.
Unyeasted pastry forms are usually grouped under the heading of puff pastry (Thacker, 1997), while the yeasted forms are a more diverse group (most commonly recognised forms include croissant and Danish pas-tries (Bent, 2007)). The laminated structure, along with a low moisture content in some cases, gives the products a characteristic ‘flaky’ struc-ture and eating quality (Cauvain and Young, 2006).
The manufacture of all laminated products starts with the formation of a base dough. This is usually a relatively simple formulation of flour and water with some fat, salt, yeast (if required) and other functional ingredients. Some of the water used in the base dough formation in lam-inated products may come from additions of egg or milk products. The use of such ingredients is most common in the formulations for crois-sant and Danish pastries in order to confer particular flavours (Cauvain, 2001). The levels of fat used in the manufacture of laminated products are much higher than those seen with bread, but most of the fat incor-poration does not occur until after the dough has been formed. In these circumstances the fat plays little part in the formation of the base dough characteristics but does play a significant part during lamination and baking (see Chapter 4).
The formation of a gluten network in laminated products is important for the rheological properties of the base dough and its final structure formation. The energy imparted to the base dough for laminated prod-ucts will be somewhat lower than that typically used for breadmaking because significant levels of work are imparted to the dough during the sheeting operations that characterise these products. The base dough rheology needs to be such that the dough has good extensibility, low elasticity and low resistance to deformation. Because of these require-ments the level of water added in the formation of the base dough is particularly important.
Optimum water levels for laminated doughs vary with changes in flour characteristics in a similar manner to that seen with bread (see Chapter 2). However, the levels used in laminated product formulations are usually slightly lower (typically 3–7% lower, based on flour weight) than those used in breadmaking. These slightly lower water levels are required to compensate for the softening of the dough, which occurs because of the longer processing times that commonly apply during the
sheeting and laminating stages, in part because of the presence of the laminating fat. Telloke (1991) showed that, as expected, increasing the water level produced a softer dough with less resistance to deformation, but puff pastry lift was not affected by changes in added water from 52.5 to 62.5% of the flour weight. There was a slight decrease in pastry shrinkage over the same added water level changes.
These observations are interesting because the generation of steam from the dough water is an integral part of the mechanism by which puff pastry lifts during baking, but much of the steam generated does not take part in the aerating mechanism (see Chapter 4). Since only part of the added water provides steam for pastry lift, once a minimum level of addition is achieved the addition of further quantities becomes unnecessary, as shown by Telloke (1991). In puff pastry manufacture, it is far more critical to achieve a defined set of dough rheological properties for paste processing; it is these requirements that decide the level of water to be added to the base dough.
Optimising dough rheology, and therefore dough water levels, is also important in the production of croissant and Danish pastry. Cauvain and Telloke (1993) considered that maintaining the correct dough con-sistency was more important for croissant and Danish pastry than for puff pastry, partly because firmer doughs were more difficult to process and this resulted in less regular separation of the dough and fat layers.
Firmer croissant and Danish pastry doughs expand less readily during proof, and so by the end of a given proof time the dough pieces will be lower in proof height, which in turn will be reflected as a lower product volume. An increase in proof time can compensate for the loss of proof height, but this may lead to other quality losses, e.g. increased oiling of the laminating fat which would reduce product lift.
The control of base dough temperature in the production of puff pas-try is less critical than that of the laminating fat temperature and the paste processing temperatures. Knight et al. (1967) found no significant effects resulting from a 5◦C increase in base dough temperature, and Telloke (1991) studied the effects of changing added water temperature to give base doughs with temperatures spanning a 10◦C range with-out finding any significant effects. In the case of croissant and Danish pastry, variations in water temperature led to variations in base dough temperature – which had a more profound influence on final quality because of the effect on yeast activity, as well as dough rheology. Higher dough temperatures lead to softer doughs and increased yeast activity which leads to faster proof and potential losses of final product quality (Cauvain and Telloke, 1993).
Another type of yeasted laminated product is the biscuit cracker. In this case, the layering technique is normally based on forming a dough sheet on to which is added a ‘cracker’ dust comprising a mixture of fat
and flour, with some minor ingredients. This technique gives a prod-uct that has some limited flakiness after baking, but which is able to withstand a considerable degree of mechanical handling, including the application of butter by the consumer before consumption. The forma-tion of the base dough depends on the development of a gluten network with the correct rheological characters, and so optimising added water levels is as critical with crackers as with any other laminated product.
The precise level of added water will be influenced by the method used to make the dough, although with all methods the added water levels are lower than would typically be seen with the same flour in a bread dough.
There are three main groups of dough mixing methods for crackers:
straight dough with no fermentation (floor) time; straight dough with fermentation time and sponge and dough. Each dough mixing method requires its own combination of ingredient formulation and plant, and each produces a slightly different final product. Dough water levels will vary between the methods because of changes in dough rheology, which typically occur after mixing and during dough processing. The changes in dough properties are greatest when they are given some fermentation after mixing and before processing, or when a sponge and dough pro-cess is used. With both these methods, enzymic (or chemical) softening means that a lower water level can be used in the initial doughmaking stage.