Tunnel vision

23 September, 2011
Bespoke designs and hygiene features are winning converts to tunnel ovens. Alyson Magee examines a number of models on the market

Energy efficiency, hygiene and safe and easy access are among features winning bakers over to tunnel ovens, while bespoke solutions and versatility to alter baking programmes are closing the deal.

For Ilkley-based Spooner Industries, integrated energy-saving functions are a key facet of its tunnel ovens, offering bakery clients the opportunity to reduce wastage and improve their bottom line. An in-built energy-efficient mode can automatically lower oven temperature and airflow, while keeping the oven ready to bake, during product change-over.

Energy-saving features on the burner automatically minimise combustion air in accordance with the oven load, and Spooner has installed easy-clean integral heat recovery systems to capture flue stack energy and use it to pre-heat fresh air or for heating water.

Adjustable air systems allow Spooner's tunnel ovens to alter their baking characteristics, including adjusting heat flux at numerous points during the baking process. New innovative design features also include increased safe oven access, allowing ease of maintenance. The ovens use a forced convection system, which provides uniform airflow and an even and consistent bake quality, while the installation of radiant-effect damper systems offers versatility in the type of bake to achieve desired quality and appearance.

Speciality bread supplier New Primebake has recently completed a switch from rack to tunnel ovens across its factories in Nantwich, Barton and Crewe. Owned by the Icelandic Bakkavör Group, New Primebake produces breads for several UK supermarkets, including hand-crafted breads with toppings such as butter, garlic, cheese, olives, herbs and sun-dried tomatoes.

With the Crewe factory a recent addition, manufacturing director Mark Jones faced the challenge of doubling capacity without changing the technical specifications of the bake, and maintaining safety, as toppings such as butter and cheese can be extremely volatile. A decision was made to switch from rack/batch to tunnel ovens, specifically the Double D Continuous Baking Oven, with the aim of increasing capacity without compromising quality and safety. The ovens were supplied by JBT FoodTech, a US-owned global operator with UK sites at Broxburn and Lyddington.

"We'd been using rack ovens for over 20 years, so this was a leap of faith," says Jones. "We initially wrote a spec for 10 oven manufacturers from across the world and shortlisted five, but it was JBT FoodTech's Double D Continuous Baking Oven that ticked all our boxes."

The ovens feature Double D's Clean In Place (CIP) system, which uses sprinkler pipes to deliver a pressurised, heated, caustic solution throughout the oven, cleaning any debris or residue. "The CIP system is vital to us for hygiene and safety," says Jones. "Baking with toppings requires stricter hygiene standards, as the proteins (butter, cheese, garlic) can drip into the bottom of the oven, become trapped and create a serious fire risk.

"The Double D oven also contains a water bath, which collects and discards this volatile residue. It has halved our cleaning down-time."

The Double D Continuous Baking Oven is designed in zones for flexibility and can be programmed to suit any number of different recipes and specifications, while the travelling stainless steel band can be custom-built up to 3.6 metres wide. The oven also lays claim to a unique airflow technology and bespoke expertise, allowing customers to fulfil individual demands and specifications. Ovens have been developed specifically for pizza, quiche, pastries, pies, savouries, morning rolls and confectionery with the aim of enabling each to be baked consistently at high volumes.

Dutch manufacturer Den Boer Baking Systems has developed infrared burner technology, aimed at maximising the efficiency of its Multibake direct heated and hybrid ovens. Its ovens combine heating systems incorporating direct, indirect, impingement and infrared methods to achieve the ideal baking profile for specific product ranges.

Infrared gas heating transfers heat rapidly, penetrating quickly into the core of dough and proving ideal for very short bake processes, such as flat- and crispbreads, pizzas and pittas, according to Den Boer. It is also suitable for biscuits, which require even baking throughout the product, or pastries.

Additional features of the ovens include direct transfer of energy (without conduction and with limited air movement) from transmitter to product, precise control and power modulation, and high power density.

The infrared section of the oven is equipped with a number of stainless steel radiant burners, covered in knitted 100% metal fibre yarn, which is traceable and thus ideal for use in the food industry. The infrared technology is also applicable for melting and toasting, offering short process times, down to 15 seconds, including for example melting cheese toppings on pizza, sugar on cookies and meringue on to cakes or pies.

Den Boer is owned by Tromp Bakery Equipment, a Dutch designer and manufacturer of food processing equipment specialising in the bakery industry, with a UK base in Shrewsbury. The company has been making industrial tunnel ovens for more than 100 years, including global applications in bread bakeries, pizza plants, and on pie and puff pastry lines.

Gloucestershire-based data logging specialist Signatrol, meanwhile, says its SL Thermal Barriers are ideal for temperature profiling in hot processes and, in particular, tunnel and rack ovens used in plant bakeries. Resistant to air, water and steam, Signatrol's Thermal Barriers enable its SL700 data logger to pass through any ovens (or chillers) and provide 'through process' data logging and temperature profiling.

The barriers can be used across temperatures ranging from -150ºC to +600ºC and offer the capability to remain in process for up to six hours, making them ideal for use in bakery processing ovens.

When used in conjunction with a data logger, an accurate profile of the heating or cooling process against time can be displayed in graphical or data table format. The compact and neat thermal barrier also means that there are no trailing wires from the logger to get tangled in the conveyor or process, according to Signatrol.





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