Freezing is a food preservation method that has been used for thousands of years. Today’s frozen food technologies encompass numerous types of equipment and processes to preserve food.
Flash freezing is one of the most common methods used in food preservation. In the 1920s, Clarence Birdseye discovered the benefits of freezing fish, noting that lower temperatures accelerated the freezing process and made the fish more palatable. In 1925, Birdseye invented a device that used a pressurized brine and water solution to rapidly freeze vegetables for transport. This technology allowed producers to sell their frozen products all across the country.
To this day, flash freezing has remained a popular method of preserving foods for transport and long-term storage. This century-old, safe, and cost-effective method is being refined constantly.
In this blog post, we will be looking at some of the most common frozen food processing equipment in the industry today.
Main Equipment Considerations for Frozen Foods
There are several ways we can categorize modern equipment for freezing. Based on the way it operates, it can generally be divided into two principal groups:
- Integrated into the processing line for a continual flow
- For freezing the product in batches
Depending on the heat-transfer method, freezing equipment can be classified into three main groups:
- Air-Blast Freezers – Using moving, frigid air to cool the food. These are the most common freezers and are available in many different designs.
- Contact Freezers – Conduction is the primary method of heat transfer. The food is frozen by bringing it in contact with extremely cold surfaces or by immersion in a cold liquid.
- Cryogenic Freezers – This technology uses liquefied gases, such as nitrogen or carbon dioxide, to produce frigid temperatures.
Depending on necessity, there may be combinations of these three heat-transfer methods used in special designs.
In addition, freezing equipment can also be categorized into two main groups based on the frozen food product. These include:
- Individually Quick-Frozen (IQF) Products – IQFs are food products where each piece of food is frozen separately before packaging. Common examples include fruits (i.e., blueberries or strawberries), vegetables (i.e., peas, corn, green beans), seafood (i.e., scallops or shrimp), or poultry (i.e., individual chicken breasts). Even whole poultry products, like frozen turkeys, are processed under the IQF method.
- Packaged Products – These are typically bulk frozen foods that are packaged before freezing.
While all of these freezing methods are used in the frozen food processing industry, the systems preferable for high production rates are those that are integrated with packaging operations to provide a continuous flow of products.
A piece of comprehensive freezing equipment needs to be designed to accommodate all the stages in the freezing process, optimizing every aspect of it. This includes design for hygienic compliance with safety and sanitation standards and minimizing product loss rates through efficient operation. It also should have minimal maintenance requirements because these factors significantly contribute to the cost-efficiency of the system.
Below, we’ll provide a short rundown of the technologies and equipment used in the frozen food industry.
Food Freezing Equipment
When it comes to food freezing equipment, the three broad heat-transfer method categories can be further divided as follows:
- Sharp Freezers – Also known as blast rooms, sharp freezers are cold storage rooms. There usually isn’t any forced airflow, resulting in a slow freezing rate. This equipment is typically used for bulk products, such as beef quarters, and not on processed foods.
- Tunnel Freezers – Refrigerated air is circulated over the product that’s placed on trays or special spacers. The trays or spacers either stand in or are passed through the tunnel in racks or on trolleys.
- Belt Freezers – single-, multi-, or spiral-belt freezer systems typically use a vertical airflow, forcing cold air through a product layer that’s evenly distributed over the entire belt area. This creates ample contact with all product particles. Of the three models, the spiral belt freezer offers the most flexibility regarding the product range handled and maximizes the belt surface area in a given floor space. Meat patties, bakery goods, fish cakes, and filets are commonly processed in these systems. They can either be frozen raw or prepared, packaged or unpackaged.
- Fluidized-Bed Freezers – Fluidization occurs when individual food particles of relatively uniform shapes and sizes (i.e., peas) are subject to an upward airstream. After a certain air velocity, these particles will float in the air stream and separate from one another, allowing for more uniform freezing.
- Immersion Freezers – consist of a tank of a cooling solution, such as salt, sugar, or alcohol and water. The product is immersed in this brine or is sprayed while being conveyed. Turkeys and other poultry are typically frozen with this method.
- Plate Freezers – Either vertical or horizontal, manual or automatic, plate freezers sandwich the product between two metal plates for rapid heat transfer.
- Band Freezers – These are used to freeze thin product layers. The product is formed and frozen between two endless stainless steel bands, resulting in a frozen mat. Typical products include fruit pulps, egg yolks, sauces, chopped spinach puree, or liquid food such as soups.
When the product development process is in its early stages, cryogenic freezing can be a valuable way to achieve low-temperature storage quickly. This allows for quick cooling and handling of wet, sticky, or otherwise sensitive products before they are frozen solid with airflow or contact freezers as needed by larger-scale operations later on down the line.
Some types of food processing require cryogenics fluids like carbon dioxide or liquid nitrogen. Not only does this help speed up processes, but it also helps reduce damage during production.
Frozen Food Packaging Technology
Depending on their moisture content, most frozen foods can expand by as much as 9%. As such, the frozen food packaging material needs to accommodate these changes. In addition, the type of packaging chosen needs to:
- Withstand freezing temperatures of -40°F.
- Have a food packaging design that offers a good visual appeal.
- Sustain the sealing, freezing, storage, and transportation processes and, in some cases, cooking pressure.
Below are some of the commonly used materials in the packaging process:
- Polyethylene (PE) Film – PE films can withstand low temperatures of -40°F, have good mechanical strength, and are puncture resistant.
- PE Derivatives – Different plastics can be used for frozen food packagings, such as shrink wraps, rigid materials, flexible plastics, and single-use packaging.
- Polyethylene Terephthalate (PET) – This material can withstand abrupt temperature changes and is generally used in microwavable or boil-in-the-bag products.
- Cardboard and Laminated Paper – Commonly used in fast-moving consumer goods (FMCGs), these packages have a limited shelf life after taking the product out of the freezer.
- Tin Cans – These were the traditional frozen food packaging material but are less cost-efficient when compared to the alternatives.
- Aluminum Foil Laminates – These offer the best results in water transmission, oxygen permeability, thermal and mechanical stability, and sealing quality.
Maintaining proper hygiene during the frozen foods packaging process is of the utmost importance.
Even if freezing stifles microbial growth, it doesn’t eliminate it completely. And after thawing, microbial growth will pick up again.
Frozen food manufacturers have several options for cleaning within the packaging line. Below are some of the most common:
- Dry Wipe Down – This process involves cleaning the product and packaging with a microfiber cloth at room temperature.
- Low-Pressure Cleaning – Also known as soft-wash, this process involves low-pressure nozzles that spray distilled water or other solutions to wash off packaging and product surfaces.
- High-Pressure Cleaning – Generally, high-pressure cleaning for frozen food packaging equipment includes spray nozzles, air-dryers, and a hot/cold water setting.
Frozen Food Packaging Sealing Technology
A good sealing will ensure the overall safety and quality of the end product by protecting it from the external environment. Depending on the type of packaging film, there are several methods and packaging machines available:
- Direct Heat Sealing – This system can be used on various plastic packaging materials, notably thicker ones like polypropylene.
- Impulse Heat Sealing – This system applies an electrical impulse in a piece of wire that’s heated and cooled. Impulse heat sealing is a more cost-effective alternative to direct heat sealing.
- VFFS Systems – VFFS packaging represents vertical forming, filling, and sealing technology, a packaging system of filling and sealing the product within the same production line.
- Zip-Locks – This type of sealing technology is gaining popularity in the frozen food market because of the increased convenience and overall quality, and visual appeal of the packaging. They are often used in combination with a heat sealing method.
Frozen Food Conveyor Systems
Regardless of the freezing or packaging equipment, frozen food manufacturers need to maintain their food safety and food quality standards throughout the process. To do so, they need a conveyor system that will guarantee this high level of security and one that will minimize or even eliminate any product loss during frozen food production and processing.
Cablevey’s Frozen Food Conveyor Systems are suitable for moving all sorts of food batch ingredients and finished products safely, gently, and in a sanitary manner, no matter the material. These highly flexible systems can be engineered to service any part of the production process from mixing, pretreatment, freezing, and packaging, and they can be used in a wide range of applications. Cablevey’s frozen food conveyor systems come in different sizes and offer a full range of different components to cover any facility layout, and conveyor movement needed.
In most frozen food applications, bucket elevators and open conveyors such as belts can often result in significant product spillage and warming, a severe quality and efficiency concern.
However, with cable, disc, and tube conveyors, these are no longer an issue as the product travels through an enclosed environment. Utilizing clear tubing can eliminate the appearance of black specks occurring on the product, which many companies have noticed while using other types of conveyors. Cablevey’s conveyor systems can minimize this problem.
If you’d like to know more about Cablevey’s conveyors for the frozen food industry, please contact us.