Harris Protecting food from spoilage
The role of carbon dioxide and nitrogen in modified atmosphere packaging
Food producers know that today’s consumers want fresh products that are minimally processed but also have long shelf life. To achieve this, the industry is increasingly relying on modified atmosphere packaging (MAP), which uses gases to control and slow oxidation of fresh food.
Covid-19 has driven even more use of this type of packaging, for a number of reasons. First, wrapped fresh foods appear safer to many consumers than unpackaged raw fruits and vegetables, as the food is protected from contamination by grocery employees and other shoppers. There is no report to date that the virus can spread through the consumption of food, particularly meats and poultry, but the uncertainty can weigh on the minds of some consumers.
Secondly, before vaccines were available, people were shopping less frequently, buying more food per trip and needing fresh foods to last longer. Seeing these trends, food producers continued turning to MAP to meet consumer needs.
In another food industry category, meal-kit makers that ship ingredients directly to consumers have seen tremendous growth as a result of Covid-19, as many people have wanted to avoid grocery stores. This has led to increased use of gases in food packaging.
How MAP works
Because MAP creates and maintains an atmosphere inside a package to prevent oxidation, this technique reduces spoilage, off-textures, odors, and discoloration, such as lettuce turning brown or apples becoming mealy. By preventing oxidation, the useful life of fresh products is greatly extended and their visual appeal is kept intact.
Two popular gases for extending the shelf life of fresh items are nitrogen and carbon dioxide (CO2). The air inside the package is replaced by pure gas or a gas mixture. Gas blends can come premixed from the distributor or blended on-site.
For many foods, the MAP process involves excluding oxygen, however an exception is red meat such as ground beef and steak. In this case, a very low concentration of CO is added to the packaging to maintain the red color; otherwise, the meat could turn gray and consumers will likely consider it to be spoiled. The packaging is either vacuum-packed or pressure-packed. The latter has a balloon-like feel when pressed.
A notable trend is that fewer grocery stores are cutting their own meat, instead relying on meat packers to butcher and package the meat at or near the slaughter point. This is an area of growth for packaging companies and gas suppliers.
Common types of Modified Atmosphere Packaging
The most widely-used MAP process utilizes a nitrogen gas flush. Nitrogen gas, which is inert and safe to use in food packaging, is pumped in to displace oxygen right before sealing.
Using MAP technologies, food producers can dramatically extend the shelf life of produce. Oxygen levels between 1% and 5% will delay oxidation, while concentrations below 8% will delay ripening and maturation.
Apples can last for up to 11 months at 1 - 2% oxygen levels, while bananas maintain freshness for only 15 days, using 2 - 5% oxygen levels. Lettuce can look fresh for 3 - 4 weeks, at 1 - 3% oxygen, and onions are good for 8 months (1 - 2% oxygen levels).
With the growth in popularity and convenience of fresh-cut vegetables and fruits, nitrogen gas flush is increasingly used during the packaging process.
Nitrogen, which is supplied from a cylinder or bulk tank, or generated onsite, is pumped into each package before the package is sealed.
As an added protection to keep food fresh, many produce companies are also utilizing high-barrier films that feature low oxygen transfer rates. These films have low oxygen permeability which provides even more protection against oxidation.
Microbial growth can also be slowed for some produce by using trace amounts of nitrous oxide (N2O), argon (Ar) and hydrogen (H2).
Reliable Gas Distribution
The standards required by modified atmosphere packaging are comparatively high and must be controlled and monitored to ensure food safety. It’s critical to have a reliable gas distribution system -- such as high purity manifolds, regulators and flowmeters -- to safely deliver the gas at the correct pressure and flow rate to the packaging line.
Gas blenders provide the option to adjust gas ratios as needed. This option saves money as it costs less to blend gas on-site than to purchase pre-mixed gas. It’s also more convenient for the packaging facility as different mixtures can easily and quickly be produced.
Chrome-plated and stainless steel regulators are usually specified for food packaging. Stainless steel is a popular choice as it allows for easier cleaning. The Harris Model 742, a stainless steel, two-stage regulator with steady pressure regulation and high purity stainless steel components in the gas path, is ideal for this application.
Switchover manifolds are also important for food packaging processes, as they provide uninterrupted service. When a cylinder runs out of gas, the system immediately draws from the next cylinder, preventing packaging machine downtime.
Multiple levels of manifolds are available, and can be selected based on the type of gas, flow rate and purity levels required.
Having a telemetry system connected to the manifold is very helpful. For example, the Harris DataSMART® automatic switchover manifold provides many datapoints to help food packagers effectively manage gas usage. One feature is the monitoring of the volume of gas remaining in the tank and the automatic alert that is sent when the volume reaches a pre-designated low point. This not only helps the packager to know when to order gas, but also helps them to minimize wasting gas when the tank is sent back to the distributor with gas in it.
Gas distributors benefit from manifolds that have advance reporting features as it helps them plan deliveries in advance, avoiding unnecessary trips and routing their deliveries more efficiently. Some industry experts have stated that telemetry systems can reduce transportation costs by 30 to 40%.
Gas distributors should consider suppliers who provide turn-key solutions that include not only the proper combination of products but also custom schematics. Available from Harris at no extra charge, drawings can help customers visualize and verify the item is what they want and will fit in the available space. Space limitations can be addressed in advance, saving time and headaches when the system is delivered.
Currently, high purity gases and equipment are not required for food packaging, however many predict the FDA will introduce new regulations which will impact the industry.
With the uncertainty of regulations and the complexity of the packaging market, it is important to rely on a gas distribution equipment manufacturer like Harris Products Group, who knows the industry well. It’s not always necessary for a distributor to have in-house technical staff when they can partner with a manufacturer who can provide that knowledge and service.
Extending the shelf life of perishable food benefits the bottom life for food producers and grocery stores, so MAP is likely to continue growing in popularity going forward. This offers great opportunities for gas suppliers to grow sales and expand their business.
Just as food sustains us, the food industry can provide long-term sustenance for distributors, whether they’re just entering this market or they’ve been doing it for many years. Being able to partner with an experienced equipment manufacturer makes it an even more appealing area of focus for gas distributors.
gasworld US Edition • December 2021 • gasworld.com/specialfeatures