Baking Biscuit Cracker and Cookies by Infrared Radiation

March 5th, 2021

by Iain Davidson of Baker Pacific Ltd

Baking Biscuit Cracker and Cookies by Infrared Radiation

1 Crackers

FIG 1 Soda and saltine crackers

1.1 Structure

The crackers require an open, flaky structure and light crispy texture. This requires a high heat input in the first one-third of the oven. The heat input is provided by radiation from the Direct Gas Fired oven zones and conduction from the pre-heated Compound Balanced Weave band. The first zones have minimum extraction and no convection. Humidity is important and the initial temperature rise of the dough pieces is faster with a moist atmosphere. In a Direct Gas Fired oven about 30% of the humidity is from the products of combustion. Steam may also be applied at the oven feed end. The surface of the dough pieces must remain flexible to lift and achieve the required volume and thickness of the cracker.

FIG 2 Baker Perkins Direct Gas Fired Oven with pre-heat burners

FIG 2 Baker Perkins Direct Gas Fired Oven with pre-heat burners

1.2 Moisture content

Cracker doughs have a high percentage of water, approximately 20 - 25 % of the total dough weight. The moisture is removed in the middle and final zones of the oven. The moisture content will be reduced to 1.5 – 2.5% of the product weight. This requires the evaporation of approximately 200 g of water for every kg of cracker baked. This requires heat transfer of 108 kcal for the latent heat of vaporisation per 1kg of baked cracker or 108,000 kcal (125kWh) for every 1 tonne of baked cracker.

Latent heat of evaporation: 539 kcal / kg

The evaporation of the water requires a high heat input. The cracker oven will have a high heat rating based on the radiant heat transfer and conduction from the pre-heated oven band. Heat transfer in the middle and final zones of the oven can be enhanced by the turbulence system.

1.3 Colour

Radiant baking in the final oven zones is essential to achieving colour contrast for the crackers to show darker blisters and a pale background.

Soda Crackers

FIG 3 Soda Crackers

1.4 Oven specification

Direct Gas Fired Oven with turbulence and pre-heated Compound Balanced Weave band.

Typical baking time: 2.5min
Oven set temperatures: 300/300/280/250

1.5 Baking profile

FIG 4 Baking profile for soda crackers

1.6 Heat rating

FIG 5 Heat ratings for soda crackers

>How to Bake Crackers by Infrared Radiation?

2. Snack crackers

Snack crackers

FIG 6 Snack crackers

2.1 Structure

There are a variety of textures, from the open layered crackers, even textures such as ‘TUC’ type and hollow products such as fishes

‘Ritz’ type - laminated

FIG 7 ‘Ritz’ type - laminated

FIG 8 ‘TUC’ type - sheeted and cut

FIG 9 Fishes type – rotary cut without docker pins

2.2 Baking process

The first zones have minimum extraction and no convection. The surface of the dough pieces must remain flexible to lift and achieve the required volume and thickness of the cracker. Most snack crackers are baked on Z47 type open wiremesh oven bands. Fishes may be baked on a Compound Balanced Weave band.
Z47 wire mesh oven band

FIG 10 Z47 wire mesh oven band

2.3 Moisture content

Snack cracker doughs have a high percentage of water, approximately 10 – 20% of the total dough weight. The moisture is removed in the middle and final zones of the oven. The evaporation of the water requires a high heat input. The cracker oven will have a high heat rating based on the radiant heat transfer. Heat transfer in the middle and final zones of the oven can be enhanced by the turbulence system.

Water in the dough Final moisture content

Ritz type: 15 - 20% 1.3 – 2.0%

TUC type: 10 – 13% 1.5%

Fishes type 18% 2.0 – 3.0%

The evaporation of the water requires a high heat input. The cracker oven will have a high heat rating based on the radiant heat transfer. Heat transfer in the middle and final zones of the oven can be enhanced by the turbulence system. Time and infrared radiation, which penetrates the dough pieces, are important to achieve the most even moisture content from centre to outside of the cracker.

2.4 Colour

The snack crackers generally have a very even colour achieved by radiant heat with turbulence.

2.5 Baking times and temperatures

Ritz type:
Baking time: 3.5 – 4.0 min
Oven set temperatures: 220/230/240/240/220

TUC type:
Baking time: 4.5 – 5.0 min
Oven set temperatures: 280/270/230/200/200/150

2.6 Baking profile

FIG 11 Baking profile for Ritz type cracker

3. Semi-sweet biscuits

3.1 Structure

Examples of semi-sweet biscuits are Marie, Petit Buerre, Rich Tea, Arrowroot, Breakfast biscuits. They are characterised by an even, attractive colour with smooth surface sheen, light texture and good volume. The surface of the dough pieces must remain flexible to lift and achieve the required volume, texture and thickness of the biscuit.

>Marie Biscuit Recipe and Process Guide

The dough sheet is cut at 1.3mm. A good Marie biscuit will attain a thickness of 5.6 – 6.0mm.

Doughs for semi-sweet biscuits have the following features:

Doughs have strong, developed gluten which gives an elastic dough, which is sheeted and cut. It often shrinks in the first stage of baking
Doughs have relatively low sugar and fat
Biscuits are normally baked on a wire-mesh band (except for Marie which is traditionally baked on a steel band).
Humidity in the first part of the baking is important to achieve good volume and a smooth surface sheen. The initial temperature rise is faster with a moist atmosphere than in a dry oven.
Biscuits are baked to low moisture contents, around 1.5% - 2.0%

FIG 12 Steinhaus F4012 wire mesh oven band

3.2 Moisture content

Doughs have water contents typically of around 12%. The biscuits will have final moisture content of 1.5 – 2.0%

3.3 Colour

Steam application at the oven feed end assists in developing an attractive sheen to the surface of the biscuits. The very even colour required is assisted by turbulence in the final zones.

3.4 Oven specification

Hybrid Direct Gas Fired / Indirect Radiant Oven with turbulence. Wire mesh band.

Baking time: 5.0 – 6.5 min
Oven set temperatures: 200/220/220/180^oC

3.5 Baking profile

FIG 13 Baking profile for Marie biscuits

>Process For Semi-sweet Biscuits

4 Short dough biscuits

FIG 14 Short dough biscuits

4.1 Structure

This is a wide biscuit category with many designs. The doughs are short with higher fat and sugar contents than semi-sweet biscuits. This is the simplest category for the dough piece forming process (rotary moulding) and so these products are very widely produced, often in high volumes.

Very wide variety of shapes and designs
Doughs have a low water content, but more fat and sugar than the semi-sweet biscuits
High humidity in the first part of the baking process allows the biscuit structure to form
Relatively slow baking at comparatively low temperatures

4.2 Moisture content

Doughs have water contents typically of around 4.0 – 5.0%. The biscuits will have final moisture content of less than 3.0%%

4.3 Colour

Infrared radiant heating is required to provide colour contrasts and highlight the design with darker areas against a paler background.

4.4 Oven specification

Indirect Radiant Oven with turbulence and heat recovery system.

Open wire mesh band.

Baking time: 5.0 – 6.0 min
Oven set temperatures: 180/200/220/200/180^oC

4.5 Baking profile

Baking profile for short dough biscuits

FIG 15 Baking profile for short dough biscuits

4.6 Heat rating

Heat rating for short dough biscuits

FIG 16 Heat rating for short dough biscuits

5. Cookies

FIG 17 Cookies

5.1 Structure

Chocolate chip cookies, butter cookies, two dough cookies, centre filled cookies, fig bars, fruit bars, extruded cookies, cookies with many types of inclusion such as nuts, raisins, coconut and chocolate chips.

Very soft doughs which are deposited directly onto the oven band
High fat and sugar recipes
Long baking times with relatively low baking temperatures
All products are baked on steel bands
High humidity is required in the first oven zones to allow the dough to spread on the oven band

5.2 Moisture content

Doughs have water contents typically of around 3.0 – 7.0% with an average of 5.2%. The biscuits will have final moisture content of 2.5% - 3.0%%

5.3 Colour

Infrared radiant heating with turbulence and relatively long baking time provide even colour.

5.4 Oven specification

Indirect Radiant Oven with turbulence and heat recovery system.

Steel band.

Typical baking time: 7.0 min
Oven set temperatures: 180/200/220/200/180^oC
Steel band

FIG 18 Steel band

5.5 Baking profile

Baking profile for cookies

FIG 19 Baking profile for cookies

>Process Manual for Cookies

6. Multi-purpose ovens

Crackers, semi-sweet and rotary moulded biscuits for a multi-purpose production line

FIG 20 Crackers, semi-sweet and rotary moulded biscuits for a multi-purpose production line

9.6.2 Heat rating

Heat rating chart for multi-purpose oven

FIG 21 Heat rating chart for multi-purpose oven

TechTalks discussion

First time doing crackers I have some problems
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Has anyone here successfully installed a heat exchanger on a direct oven flue line? Or heard of such a project?

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