Presently, the most common method of preserving food is freezing. A variety of different types of products can be frozen. Some include vegetables, fruit, prepared foods, pizza, entrees, yogurt, ice cream, eggs and butter, along with various kinds of meat such as fish, pork, chicken, turkey, lamb and beef.
In 1880 a cargo of refrigerated meat being shipped from Australia to Britain accidentally froze. Like the invention of penicillin the results forever changed the cold storage industry. The process was at once adopted for long-distance shipments and other kinds of storage. In the 20th century another method of freezing known as quick or flash freezing was implemented and also discovered to be especially effective with certain types of food.
Extreme cold inhibits bacterial growth, which means that if food is handled safely and then placed immediately in the freezer, the likelihood of contamination is very low. This increase in food safety reduced risk to the consumer. As a result, quick freezing became popular in commercial food preparation.
Since living organisms are mostly comprised of water, freezing them crystallizes this water into ice. There are two factors that affect meat quality for the consumer:
- The length of time the freezing process takes. For example, the faster seafood is frozen upon being caught the more the consumer will experience its original “wild caught” freshness.
- The micro crystalline dimension of the frozen food. The smaller the ice crystals, the less damage there is to the food. If, for example, the ice crystals are large then the cells of the organism can be ruptured when re-thawing.
Types of Commercial Freezing
Air Freezing of cartons of meat and prepared foods was the only type of freezing until the 1960s when Rapid Freezing came about. In rapid freezing cartons are placed on a pallet with air spaces between them, layers are separated with a plastic “egg crate” spacer to allow air circulation and the dissipation of heat. The most common type of rapid freezing is known as batch “blast freezing” which is used by refrigerated warehouses and cold storage facilities.
Traditional Blast Freezer
A blast freezer is a cell or room operating at temperatures ranging at -20 to -40 degrees Fahrenheit. This blast cell use fans and blowers to direct airflow as rapidly as possible through the stacked cartons. Many designs include drive in racking for multiple pallet positions, false ceilings, baffles and turbo fans to increase wind velocity. High speed roll up doors are used to minimize energy loss when loading and unloading the cell. The freezer can usually handle foods which are chilled, at room temperature, or hot, as long as it is not overloaded; too high a volume of hot food, for example, can cause the temperature in the blast freezer to rise. Blast freezers tend to eat up a lot of energy, which is why they are most commonly seen in industrial and commercial applications.
A Tunnel Blast Freezer is a high-density dynamic storage technology which continuously moves pallets of case-packed meats through progressive temperature zones. This tunnel system allows pallets to be placed adjacent to each other with appropriate pallet spacing between to allow for proper airflow. The system moves product down lanes to maximize the storage capacity of the available area while minimizing the amount of equipment inside. As product is moved in the lanes, cold air is blasted across it. Depending on where the pallets are in the system, the air will be coming from different directions. The product stays in each zone for a specific time period before moving to the next zone
New Innovations in Cold Storage
The latest advancements in freezing technologies still uses air to rapidly freeze product but utilizes pallet seals and high static fans to create negative air pressure inside a plenum. This process allows chilled air to be pulled through cases and layer spacers from the top, bottom and sides of the pallet at a rate of 200 feet per minute almost 15 times faster than traditional blast freezers. The benefits of these systems are numerous including shorter freezing times, lower energy costs, no separate blast rooms, no batching and reduced forklift “touches”.
The system uses pallet racking located in the main portion of the freezer, the system is much easier to load and unload when compared to a traditional blast cell. Additionally, you can leave pallets stored in their freezing position when you don’t need the space.
Although great improvements in freezing technologies have been made over the past 40 years the four types of plastic freezer spacers have continued to remain in very high demand. Here are the 4 designs: Egg crate, Maxi, Heavy Duty Lattice, and Open Profile.
As an alternative to wooden freezer spacers plastic freezer spacers are cleanable, stackable, reusable, and recyclable. The most popular of the plastic freezer spacers, "egg crate", is formed of a lightweight thermoformed plastic. The "heavy duty lattice" spacer molded of structural foam plastic is the most rugged and sturdy of all the designs. It is best used with product that is wet and/or bloody. It is also useful in supporting boxes that tend to deform.
The latest generation "Maxi" freezer spacer augments the original with a taller footprint and heavier gauge plastic increasing airflow through a pallet. Highly effective when used with optimized blast cell or Quick freeze plenum systems, reducing freeze times up to 17%.
Faster freezing means shipping your product earlier and converting it into revenue more quickly. Freezer spacers make cold storage more consistent, predictable, and cost effective. The use of the taller high velocity freezer spacers used in conjunction with the latest QFR Zone plenum system provides a 40% improvement (from standard cold storage methods) in removing heat from a product at a far less cost.