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Views: 0 Author: SINOBAKE-Johnson Publish Time: 2026-09-24 Origin: Site
In an industrial biscuit production line, the tunnel oven is more than a heating machine.
It is a continuous processing system in which heat transfer, baking time, moisture removal, air movement, temperature distribution, and process control work together to transform prepared dough pieces into finished biscuits.
This is why selecting an oven should not be based only on oven length, heating method, or nominal production capacity.
The oven must be matched with the biscuit type, dough characteristics, forming system, required product quality, production capacity, and the rest of the production line.
So, how does a tunnel oven actually work?
A tunnel oven is a continuous industrial baking system through which dough pieces travel on an oven band while controlled heat is applied along different sections of the baking chamber.
Unlike a batch oven, a tunnel oven is designed for continuous production.
Dough pieces enter the oven, pass through different thermal zones, undergo baking and moisture removal, and leave the oven as finished biscuits ready for cooling and subsequent processing.
A typical continuous biscuit production process can be represented as:
Dough Preparation → Forming → Baking → Cooling → Secondary Processing → Packaging
Inside the baking stage:
Dough Piece → Heating → Moisture Removal → Structure Development → Colour Development → Final Biscuit
The exact baking behaviour depends on the product formulation, dough properties, forming method, oven design, and operating conditions.
Before baking, a dough piece is still a shaped piece of dough.
After baking, it must have the required:
Shape
Structure
Texture
Colour
Moisture level
Surface characteristics
Flavour development
Baking therefore involves much more than simply raising the product temperature.
Heat must be transferred into the dough while water is removed from the product.
At the same time, the internal structure of the biscuit changes as the dough is heated.
For industrial production, the objective is not simply to produce one good biscuit.
The objective is to produce consistent biscuits continuously.
This means that the oven must provide stable and controllable conditions across the width and length of the baking chamber.
Industrial biscuit baking involves three fundamental heat-transfer mechanisms:
Radiation transfers thermal energy from heated surfaces or combustion systems toward the product.
Radiant heat can be particularly important during the early stages of baking, when the dough piece is being rapidly heated and its structure begins to develop.
Radiation also contributes to surface colour development.
Convection transfers heat through moving hot air.
In convection systems, heated air is circulated around the product and the oven band.
Air movement can increase heat transfer and help distribute thermal energy through the baking chamber.
Convection systems are particularly relevant when the oven is designed around controlled hot-air circulation.
Conduction transfers heat through direct contact.
In a biscuit oven, heat can be transferred from the oven band to the underside of the product.
The relative contribution of radiation, convection and conduction depends on the oven design and operating conditions.
The key point is that a biscuit oven is not simply a large heated box.
It is a controlled heat-transfer system.
A biscuit does not necessarily require the same thermal conditions throughout the entire baking process.
The requirements change as the dough piece moves through the oven.
For this reason, continuous biscuit ovens are generally divided into zones or sections in which temperature, heat-transfer conditions, air circulation and exhaust can be controlled.
A simplified concept is:
Zone 1 → Zone 2 → Zone 3 → Zone 4 → Final Zone
The exact number and configuration of zones depend on the oven design and product requirements.
A simplified baking profile might be understood as:
Initial Heating → Structure Development → Moisture Reduction → Colour Development → Final Baking
The actual profile must be developed for the specific biscuit rather than copied from another product.
Different biscuits may require different combinations of heat-transfer mechanisms, temperature profiles, baking times and humidity conditions.
The transformation from dough piece to finished biscuit involves several simultaneous changes.
The dough piece begins to absorb heat from its surroundings and the oven band.
The surface and internal temperature of the product begin to rise.
As the dough heats, physical and chemical changes occur within the product.
Depending on the biscuit formulation, these changes contribute to the development of the final structure and texture.
The forming method also matters.
A hard-sweet biscuit, cracker, rotary-moulded biscuit and wire-cut cookie do not necessarily behave identically during baking.
Water in the dough must be removed to achieve the desired finished product characteristics.
Moisture movement and evaporation are therefore fundamental parts of industrial biscuit baking.
The oven must provide sufficient thermal energy while allowing moisture and vapour to be removed through the appropriate exhaust system.
As baking progresses, the biscuit develops its final surface appearance and colour.
The required colour depends on the product.
A pale biscuit, a golden-brown biscuit and a darker cracker may require different baking conditions.
This is one reason why baking should be considered as a profile, rather than a single temperature setting.
Toward the end of the oven, the process must bring the biscuit toward its target final condition.
The product must leave the oven with suitable structure, colour and moisture before entering the cooling section.
Moisture removal is one of the central functions of industrial biscuit baking.
As the dough is heated, water is released as vapour.
If the baking chamber does not manage this vapour appropriately, the baking environment can change and the product may not develop the required characteristics.
Therefore, oven design includes not only heating systems but also:
Exhaust systems
Air circulation
Dampers
Fans
Moisture removal
Pressure management
The objective is not simply to remove as much air or vapour as possible.
Exhaust must be controlled as part of the overall baking process.
Excessive extraction can increase heat loss, while insufficient extraction can affect the baking environment.
Tunnel oven design therefore involves balancing heat input, air movement and moisture removal.
One of the most important concepts in industrial biscuit baking is the baking profile.
A baking profile describes how thermal conditions change as the product travels through the oven.
It is influenced by:
Oven zone temperatures
Baking time
Oven length
Band speed
Heat-transfer mechanism
Air circulation
Exhaust
Product loading
Dough characteristics
Biscuit thickness and geometry
This means that two ovens with the same nominal temperature may produce different results if their heat-transfer conditions and profiles are different.
Similarly, increasing oven temperature does not automatically mean that production quality will improve.
The target is a suitable relationship between:
Temperature + Time + Heat Transfer + Moisture Removal
For continuous production, this relationship must remain stable.
Industrial biscuit ovens can use different heating and heat-transfer arrangements.
The appropriate system depends on product requirements, available energy sources, factory conditions, production capacity and process objectives.
Electric ovens generate heat through electrical heating elements.
They can provide controlled heating and are suitable for factories where electrical energy is available and appropriate for the production plan.
SINOBAKE uses electric oven configurations including far-infrared heating and electric hot-air circulation.
In an indirect hot-air circulating oven, heat is transferred to circulating air through a heating system rather than directly exposing the product to combustion gases.
The heated air is circulated through the baking chamber.
This approach provides controlled convective heat transfer.
Hot-air circulation can also be combined with diesel or gas-fired heating systems.
The burner provides the thermal energy while the heated air is circulated through the baking chamber.
In a direct gas-fired system, combustion occurs within the baking system and the resulting thermal environment is used directly for baking.
This configuration can provide strong heat transfer and is used for suitable biscuit products.
Hybrid ovens combine different heating or heat-transfer mechanisms.
For example, a hybrid gas oven may combine direct gas combustion with hot-air circulation.
The purpose is to provide greater flexibility in controlling heat transfer during different parts of the baking process.
A modern industrial biscuit oven requires more than burners and heating elements.
It also requires a control system.
Depending on the oven design, process control may include:
Temperature monitoring
Zone temperature control
Fan control
Exhaust control
Band speed
Baking time
Top and bottom heat balance
Safety monitoring
Alarm systems
PLC-based control
The objective is to maintain repeatable process conditions.
For example, if the oven temperature fluctuates significantly or the band speed changes unexpectedly, the baking result can change.
For this reason, oven control should be considered as part of the production system rather than as an independent electrical function.
The tunnel oven cannot be designed independently from the rest of the production line.
The upstream forming system determines the characteristics of the dough pieces entering the oven.
For example:
Mixing → Resting/Preparation → Sheeting → Laminating → Gauging → Cutting → Baking
may be appropriate for certain hard or semi-sweet biscuits.
A rotary moulding process may be used for another product type:
Mixing → Dough Preparation → Rotary Moulding → Baking
For cookies:
Mixing → Dough Preparation → Wire Cutting / Depositing → Baking
The oven must then be followed by suitable cooling and downstream equipment.
A complete production system therefore needs to consider:
Forming → Oven → Cooling → Secondary Processing → Packaging
The oven capacity should also be compatible with the upstream forming capacity and downstream handling capacity.
A high-capacity oven does not automatically create a high-capacity production line.
When planning an industrial biscuit production line, it is useful to evaluate the oven from several perspectives.
Factor | Key Question |
|---|---|
Product | What type of biscuit will be baked? |
Dough | What are the dough characteristics? |
Capacity | What output is required? |
Baking time | How long does the product require in the oven? |
Oven length | Is the available baking length suitable? |
Heating system | Which heat source and transfer method are appropriate? |
Baking profile | Can different sections be controlled as required? |
Moisture | How will moisture and vapour be managed? |
Cooling | Can the downstream cooling system match oven output? |
Energy | What energy sources and operating costs are involved? |
Control | How will temperature and process conditions be monitored? |
Factory layout | Is sufficient space available for installation, access and maintenance? |
Safety | Are appropriate safety and protection systems included? |
This is why an oven quotation should not be evaluated only by comparing length, price or nominal capacity.
The more important question is:
Can the oven provide the process conditions required by the products that the factory intends to manufacture?
For investors and production managers, the oven can be understood through five connected questions:
Different biscuit types have different baking requirements.
The forming method, dough properties, thickness and product geometry influence baking behaviour.
Heat must be transferred into the product while moisture is removed and the required structure and colour are developed.
Temperature, baking time, air movement, exhaust and other process variables need to be monitored and controlled.
The oven must be balanced with forming, cooling, secondary processing and packaging.
This systems approach is more useful than selecting an oven as a standalone machine.
A tunnel oven is the thermal heart of a continuous biscuit production line.
Its function is not simply to heat dough.
It must manage heat transfer, baking time, moisture removal, temperature profiles, air movement and process control to transform formed dough pieces into consistent finished biscuits.
The right oven therefore depends on more than production capacity.
It must be matched to:
Product Type → Dough Characteristics → Forming Method → Baking Profile → Required Quality → Production Capacity → Factory Conditions
Understanding these relationships is the foundation for making better decisions when planning or upgrading a biscuit production line.
At SINOBAKE, we approach biscuit production as an integrated system rather than a collection of individual machines.
Contact SINOBAKE to discuss your production requirements.
Website: www.sinobakesnacks.com
Johnson | WhatsApp: +86 159 1810 5286
A tunnel oven is a continuous industrial baking system in which dough pieces travel through a controlled baking chamber on an oven band. Different sections of the oven can provide different thermal and air-flow conditions during baking.
The oven transfers heat to dough pieces through mechanisms such as radiation, convection and conduction. As the products travel through different zones, they are heated, undergo structural changes, lose moisture and develop their final colour and texture.
Different stages of baking require different process conditions. Dividing the oven into zones allows the baking profile, heat transfer and moisture removal to be controlled more precisely.
A baking profile describes the changing thermal conditions experienced by the biscuit as it moves through the oven. It is related to oven temperature, baking time, heat transfer, air movement, exhaust and product characteristics.
Direct gas-fired systems use combustion directly within the baking environment, while indirect systems transfer heat to the baking environment through a separate heating or heat-exchange arrangement. The appropriate system depends on the product and process requirements.
No. Production capacity depends on the complete relationship between product loading, forming system, band width, band speed, baking time, oven design and downstream equipment.
Moisture must be reduced to the required final level while the biscuit develops its desired structure, texture and appearance. Exhaust and air management are therefore important parts of oven operation.
Industrial ovens can use zone temperature sensors, controllers, fans, dampers, burners or electrical heating systems and PLC-based control systems to maintain process conditions.
The oven and forming system should normally be considered together. Product type, dough characteristics, forming method, target capacity and baking requirements all influence the overall production-line design.
Important factors include biscuit type, dough characteristics, required capacity, baking time, oven length, heating system, baking profile, moisture removal, energy source, control system, factory layout, safety and downstream cooling requirements.
