Spiral Ovens for Food Processing: A Buyer’s Guide

Are you ready to make the move from batch to continuous processing? Or do you have an aging oven on your line that’s costing you too much in maintenance and downtime?

When it comes to upgrading a production line or replacing an oven, many food processors are choosing to switch from a linear configuration to a spiral one. This is because spiral ovens offer higher production output within a smaller footprint. They also result in higher yields, improved efficiency, and more flexibility so you can meet today’s constantly evolving demands.

This buyer’s guide explains how spiral ovens work, the benefits they have over other cooking processes, and how to decide which oven is right for you.

Download this guide to share with your team

Linear vs. spiral oven cooking process

A traditional linear oven is just that: linear. You put the product in one end, and it moves through the cooking chamber and exits the other end.

Rapidflow linear oven

Unitherm launched its first linear oven, the Rapidflow, in 1987.

Linear ovens have many advantages. At the top of the list is the capability of multiple cooking zones that can be independently controlled. This is useful when you want to start products at a high temperature and then reduce the temperature to finish the cooking cycle. Linear ovens are also perfect for processing large products, for example, roasting whole hams or turkeys and browning pies and quiches.

Linear ovens are less ideal for cooking smaller products, like bacon, chicken breasts, or cut vegetables. This is because the machines have a large footprint and, since they’re linear, limited production capacity.

A spiral oven solves this problem by providing higher throughput, while also reducing the machine’s footprint.

Here’s how it works —

In a spiral oven, the food product travels on a continuous conveyor upward through a series of circular tiers within a cooking chamber. This significantly increases the belt length compared to a similarly sized linear oven, instantly boosting productivity.

Unitherm mini spiral oven

Unitherm mini spiral oven

Benefits of spiral ovens

A spiral oven offers myriad benefits that improve your productivity and also the quality of your product.

Higher throughput in a smaller footprint

As you can see from the image above, a spiral oven can accommodate a longer belt than a linear oven. Compared to a microwave line, the spiral oven footprint is even more compact — a single spiral can produce the same output as three microwave lines…in just 20% of the space.

Spiral ovens can also be fitted with different numbers of circular tiers, depending on the application. For example, you could have a five-tiered oven for cooking whole chickens, an eight-tiered oven for cooking chicken breasts, and an ten-tiered oven for cooking bacon.

Meet the world’s smallest spiral oven >>

Better consistency

In non-spiral processes, it can be difficult to maintain consistency across products. In batch ovens, products on the top rack may not be exposed to the same temperature as products on the bottom rack. In linear ovens, depending on the design, products on the edges of the belt may be undercooked, while those in the middle may be overcooked.

Unitherm’s spiral ovens allow you complete control over cooking time, temperature, humidity, and fan speed. And our specifically designed and engineered airflow ensures every product is processed exactly the same.

Higher yields

In addition to processing more product, spiral ovens give you higher yield. This is because the design allows you to capture and use the juices normally lost during cooking.

In a spiral oven, products enter the cooking chamber at a lower inlet and travel in ascending circular tiers. The rendered fat drops from products on the top tiers to the products on the tiers below, providing a self-basting function. This not only increases yield 1-2% compared to traditional cooking processes, but also improves the flavor, aroma, and appearance of the product.

The video below shows how Unitherm’s patented process for cooking bacon in a spiral oven. The result: precooked bacon that looks and tastes homemade.

“Taste and appearance were deciding factors in the purchase of our spiral oven….The spiral oven replaced two linear electric belt grills so there was an immediate savings in electrical energy, labor, and space. It is a compact piece of equipment and requires fewer personnel to produce the same output.” ~Martin Croteau, plant manager at Olymel, Cooking Bacon, Canada

Improved efficiency

Margins in the food industry are low, which means efficiency is the key to profitability. Thanks to their unique design, spiral ovens boost efficiency by enabling shorter cooking times as well as reduced labor and energy consumption.

First, the airflow within the cooking chamber is optimized to reduce cooking times. For some products, like chicken breasts or burger patties, cooking times can be reduced even further by putting a flame grill before the oven on the processing line.

Spiral ovens also use significantly less energy than traditional processes. Once an oven reaches the desired temperature, it requires only 65% energy consumption to hold that temperature.

Unitherm spiral ovens are 4x more efficient than thermal oil ovens >>

Maximum flexibility

Consumer demands change all of the time, as evidenced by the large number of SKUs being released on a near-constant basis. For many processors, the days of running the same product on your lines day in and day out are history.

Spiral ovens provide the flexibility you need to meet your customers’ demands. They can be used for baking, broiling, roasting, steaming, or a combination. They also work across product lines, from beef, pork, and poultry to vegetables, starches, ready meals, pouches, and more. You name it, chances are a spiral oven can cook it!

Types of spiral ovens

Spiral ovens can run on either gas or electric heat. Unitherm spiral ovens come in two main types: impinging and convection. Which one is right for you depends on your application.

Spiral convection oven

In a convection oven, fans distribute warm air evenly around the product. This type of oven is best for products that are irregularly shaped and where optimum uniformity is desired, such as whole birds, meatballs, ready meals, and bacon.

Airflow in Unitherm spiral convection oven

Airflow in Unitherm spiral convection oven

Spiral impinging oven

In an impinging oven, nozzles direct high-velocity airflow onto the surface of the product. This type of oven is best for products that have flat surfaces or when air can be driven into the product, such as chicken breasts, CPET trays, and patties.

Airflow in Unitherm spiral impingement oven

Airflow in Unitherm spiral impingement oven

More resources

This is just an overview of spiral oven technology and the benefits it can bring to your operations. If you’d like to learn more, check out these resources:

If you have any questions about spiral ovens, contact us — we’re here to help! If you’d like to see a Unitherm spiral oven in action with your products, visit one of our three global test kitchens.

Download this guide to share with your team

Leave a Reply

Your email address will not be published. Required fields are marked *

Translate »