Engineered for high volume, spiral ovens are used to cook a multitude of foods. The Heat and Control spiral oven provides maximum baking capacity with a small footprint as an alternate solution to tunnel ovens.
It was developed to cook large amounts of meat, poultry, prepared foods, bakery items, breakfast cereal, and even dehydrated fruit and vegetables.
The oven can partially or fully cook a product and even facilitates dehydration before further downstream processing. The ovens can also develop and enhance product colour and are suitable for products requiring a long residence time.
Heat and Control sales and marketing manager Greg Pyne told Food and Beverage Industry News that the spiral oven was best suited to medium and large-scale producers.
Pyne also explained the differences between the single drum and twin drum options.
“A single drum has one heating zone. All the product inside this oven is exposed to the same cooking environment. This can result in lower yields compared to the same product cooked in a twin drum,” said Pyne.
“The twin drum has the advantage of setting two very different cooking environments within the one system. The ‘up-drum’ can be set with high humidity to cook but not dry out a product, while the down drum can be set with a drier environment, often used to develop product colour.
“This results in less moisture loss from the product and reduced loss of yield. Available factory space often determines which oven is chosen.”
The spiral oven is typically placed down-stream from a frying system and up-stream from a freezer. The fryer sets up the coatings and then the spiral oven is used to further cook the product and develop its colour.
The product is versatile in its ability to use dry heat, steam only, or a combination of the two.
“Dry heat is used to develop and enhance product colour. The downside of this method is that moisture evaporates from the product resulting in smaller yields,” said Pyne.
“Moisture loss from the product also affects texture and palatability. By reducing moisture loss, a producer ensures higher product weights and a better tasting product, which leads to increased profitability.”
A food processor may use the steam option for a 100% steamed product that doesn’t require any colour development. This method transfers energy to the product with little or no moisture loss.
“By using a combination of both steam and dry heat, a processor gets the best of both worlds. Steam helps to reduce moisture loss and combines with dry heat to create a premium finish with high product yields,” said Pyne.
The spiral oven was developed over four decades and as such has a host of features listed, including a patented moisture control system and a continuous belt washing and drying system.
“This system was originally used in our MPO oven and later adapted for our spiral oven. It is easy to use and maintain with proven reliability and doesn’t use expensive sensors requiring frequent calibration,” said Pyne.
“Water spray and belt brushes ensure that the oven’s belt is kept clean during operation. A soak tank prior to the belt wash softens and loosens baked on grime making the job of the belt brushes much easier.”
The structure of this oven doubles as pipework for a clean in place system (CIP). CIP spray balls are placed to ensure all internal surfaces are sprayed during CIP. Nozzles on the cantilevers spray directly onto the belt to assist with cleaning.
“The CIP system has a continuous filter that reduces the risk of spray balls and nozzles being blocked and this reusable filter element is easily removed for cleaning,” said Pyne.
“Settings can be saved for every recipe and there is no need to change the settings every time. Options for automatic dosage of cleaning chemicals are also available.”
The spiral oven also allows processors to use the entire width of the oven belt allowing for higher capacity outputs as well as having the capability to create a uniform temperature distribution.
“Uniform cooking temperature distribution ensures product is cooked evenly, irrespective of placement on the conveyor belt,” said Pyne.
“This benefits processors by delivering consistent results every time. The HMI/PLC provides the ability to create recipes for different products and eliminates the need for machine operators to record settings.”
The oven was also designed to be space saving and easy to move and install.
“The round shape of this oven removes any dead space from the process environment inside the oven. The round enclosure combined with a centrally located fan means products are exposed to 360° airflow during cooking,” said Pyne.
The heat source for the oven is chosen based on the product mix with thermal oil, indirect gas, direct gas steam, and electric all being viable options.
“Thermal oil, indirect gas and steam heating are usually used for meat products and are chosen so that the heat exchange (HX) can be cleaned via the CIP system,” said Pyne.
“The HX is hygienically designed to eliminate trap points for build-up. Indirect gas heated spirals are used when processing chicken products where the by-products of combustion cannot impinge on the chicken meat.”
Electrical heating can be used for dehydrators where temperatures are low or if the customer has access to cheap electricity.
The Heat and Control Spiral Oven is the only twin spiral oven that provides ‘True Two Zone’ uniform cooking control, which has been proven to cook meat products with low yield loses.
“The first zone can be used to get maximum heat transfer with a high moisture environment to gain high core temperature and ensure pathogen kill has started,” said Pyne.
“The second zone can be used to complete the pathogen kill and gain surface colour and texture without impacting on yield loss.”