The Lamination Process in Fermented Crackers

In this feature, we will look at fermented cracker production and the influence of lamination on this process.

It is common to use two types of flour in the "sponge and dough" process of fermented crackers: strong flour in the sponge stage and medium strength in the dough stage. This process usually requires a mixture of strong flour with a protein content of 13-14% and a weak flour of 8 – 9% yielding a flour of an average content of 10 – 11%.

Yeast must be used in an environment for growth, with an adequate supply of food, air, controlled temperature and humidity in the fermentation environment. The quality and temperature of ingredient water affects the fermentation process and cold or ambient ingredient water should be used. Checks should be made on the mineral content, pH, purity, and residual salt content, as these are critical in the process control parameters of the dough preparation/fermentation. Diastatic malt extract is added as a yeast food and for its alpha-amylase activity, converting a proportion of starch to simple sugars, and confers flavour to the product during the fermentation process.

It is generally accepted that fermented dough, especially soda crackers are best mixed in two stages as follows:
Sponge: About 70% of the total flour to be used, sugar, malt extract, yeast, and all the water are mixed for 2 – 3 minutes and allowed to ferment for 18 hours.
Dough: The rest of the flour, shortening, salt, and soda are mixed with the sponge for 4 – 5 minutes and fermented for 6 hours.
The objective of mixing is to blend the ingredients into a homogeneous mass and mix the dough to the desired temperature of 28 – 30°C

The sponge stage

The dough tubs should have a thin coating of fat/oil and a light dusting of flour on the inside, to allow for uninterrupted growth of the sponge during fermentation. It is traditional to use spindle mixers for the dough stage.

In the fermentation room, the temperature should be controlled between 28 – 30°C and Relative Humidity (RH) should be controlled between 75 – 80%. Good circulating air movement is desired, with the fermented sponge and dough tubs, covered with a moist and porous material, to allow the alcohol and carbon dioxide to dissipate into the atmosphere, allowing the sponge and dough expansion to prevent surface drying and skinning. Once the recipe has been selected, the most important contributor to a good cracker is the gentle handling of the dough. The dough after fermentation should be soft enough to mould easily and firm enough to hold its shape and produce a smooth surface. The process of machinery and dough should all be at the near the same temperature.

Critical parameters

The pre-sheeter’s function is to continuously compact the dough before reduction and rolling to the desired thickness.
The three-roll sheeter has large diameter top two rolls – the compression roller and transfer roller which form a triangle with the lower roller. The top two rollers are grooved to give purchase to the mass of dough in the hopper, the delivery roller being smooth for ease of release.

No thermal shocks, no mechanical shocks – not until the dough pieces are subjected to heat from the oven band and in the first zone of the oven.

Every stage in the gauging operation must be as gentle as possible and a 2:1 reduction in gauge roll gap is better than a 3:1 reduction. Never allow the dough to be crushed or folded in the gauge roll "nip". The reduction of dough to a thin sheet and the turning and folding and further reduction in successive stages have a number of effects, forcing out air, making the dough more compact. Producing a fine smooth dough surface, provided there is no crushing of the dough through the gauging rolls. Turning and folding the dough sheet evens out the stresses of rolling.

The dough is extruded from the two two-roll sheeters, and the fat/flour is dispensed between the sheets and the dough is sheeted and laminated. The dough is now reduced and travels to the final dough sheeting and gauging rolls, before cutting.

The pressures exerted on the dough sheet by the various rolls of the laminator and process line will remove carbon dioxide and other gasses produced when processing fermented dough. One must consider the physical effects occurring to the dough sheet between the pre-sheeter, laminator, gauging rolls and the oven exit. The overall product thickness is established very soon after the dough piece enters the oven due to the formation of steam, which expands and causes the cracker to increase in thickness. Re-incorporation of the recycled cut-scrap dough from the cutter can contribute to process problems, due to temperature and humidity differences, making them incompatible. A laminator is capable of producing a well-compacted dough sheet directly from the sheeter.

Products manufactured by the laminator process are: Cream Crackers; Soda Crackers; Saltine Crackers and Enzyme Modified Crackers and some Semi-sweet biscuits.

Laminating Soda Crackers with 4 – 8 layers (6 are ideal) contribute to the flaky texture. Six layers are ideal because of the gradual reduction of dough sheet from the laminator, through the reduction rolls to the cutting head.

Recycled cut-scrap dough 

Scrap dough returned should be kept as near normal to the original dough texture as possible and not allowed to dry out. Cut-Scrap dough not being evenly distributed with the fresh dough, as it is being transferred too quickly by the contact with the grooved roll of the three-roll sheeter.

Installing an adjustable dividing plate, into the hopper and introducing the cut-scrap into the back of the hopper, will retard the rate at which the recycled cut scrap is re-incorporated with the fresh dough. To get good blistering and "lift" the first zone or zone and a half in baking should be hot (by pre -heating the oven band on its return cycle (with sufficient bottom heat and a moist baking chamber (achieved by the closing of the extraction dampers in the first zone).

Closing the extraction damper and increasing the humidity in the first zone of the oven will result in an increase in stack height. The dough must be of a consistency such that when blistered by the oven on the outer layers, these layers bake, harden and remain blistered as the heat is transferred through the next dough layers. By the second zone the final cracker shape and texture has been set. The remaining zone of the oven drives off the moisture and the surface to the desired baked colour.

Stack height control 

The stack height of crackers is dependent on the interaction of several physical factors acting on and within the dough piece. An increase in the protein content of the flour will have a tendency to increase the stack height of the cracker.

By processing the dough direct from the mixer, will produce a cracker with a slightly denser structure (than if fermented), thereby reducing the stack height. An increase in the ratio of fat/flour will increase stack height. Dependant upon the desired properties of the cracker an increase in the number of laminations will reduce the stack height. Stack height is also dependant on the rate of reduction of the dough sheet during the various stages of lamination.

Variation in the dough sheet thickness will be affected by the baking profile, by its effect on the rate of rise of the dough piece. With an increase in dough sheet thickness the structure of the cracker is improved. With a decrease the structure depreciates.

"Air Wave" Technology

Several years ago, I was acting in an independent interface capacity between an equipment supplier and a biscuit manufacturer, to resolve the process issues of variances in residual moisture content, "checking" and damaged blisters in the processing of Soda Crackers.

This resulted in the development of my "Air Waves" Technology concept. I have introduced this technology as a "retrofit" installation to existing laminators for several of my customers, with a 10 – 12% in product volume of laminated fermented Soda, Saltines and Cream Crackers.

The separation of the laminated layers during baking contributed to this increase in volume, crispy and flaky texture and in the reduction of the fragility of the desirable blisters. This leads to an increased pack length for the same weight, with a lighter texture, uniform moisture (reduced tendency to checking), without the application of fat/flour dust and reduction in damaged blisters, due to the structural strength of the top and bottom surfaces.

TechTalks Discussion

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