What is the meaning of (shelf) life?
Shelf life is a common struggle for food companies. Producers and manufacturers want products to stay fresher to prolong the time to sell or use. But environmental, biological, chemical, nutritional, and quality factors ultimately affect the product when it's ready to be consumed. However, researchers are committed to innovation in shelf-life to give foods and beverages a better chance at being of high quality when consumers are ready to eat them.
"Even with simple tech that has been around forever, like canned foods, we’re seeing innovation," said Don Schaffner, science communicator for Institute of Food Technologists and professor of food science and food microbiologist at Rutgers University. "... Industry is always innovating to either keep the same shelf life with lower costs, or lower weight packaging and keep the same benefits but reach some additional benefits as well."
What is shelf life?
Mark Sewald, principal scientist for the stability testing group at Medallion Labs, which is owned by General Mills, defines shelf life in its most basic terms as "our understanding of how a product ages." That understanding is based on a body of knowledge from various test results that end with a decision on a product’s code date, also known as a "best by" date.
To build that knowledge, a product, including food and packaging, is exposed to various conditions that the product might experience in distribution to see how a product responds, Sewald said. Factors can be the product itself and the processing and packaging methods, but he says the destination’s environment also plays a major role in determining shelf life, such as comparing a product destined for Minnesota as opposed to heading to Florida.
"The goal of the storage test is to take the science and crystallize it so the business team can make a good [code date] decision with the information," Sewald said.
Schaffner, says, "Shelf life is whatever you want it to be if it’s defined in such a way that the product at the end of that shelf life has a quality that is acceptable to you as the owner of the company, and you want your name on that product. You would stand behind that product, in terms of the quality provided to the customer."
From a regulatory standpoint, that means a product must meet certain requirements, such as maintaining the nutritional value printed on the label all the way through the code date. If a product loses a certain amount of nutrients over time, it must retain the levels of nutrients posted on the label the entire time, or the company must shorten the code date or face potential regulatory consequences.
Shelf life is also be defined as having a concentration of a chemical compound or micro-organism at or below a certain level. Or, shelf life could be determined by a sensory panel that says when a product is losing its quality in terms of taste, texture, smell, and freshness, for example.
Shelf life also differs among different types of products, such as canned foods versus frozen foods "because the method of degradation chemically, microbiologically, nutritionally, those are all going to be different for all those different products," Schaffner said.
"That’s part of why shelf life is really so complicated and so slippery," he continued. "There may be multiple things that are going on with the product at any one time. It may be changing microbiologically, chemically, nutritionally. And all of those things may potentially come into play."
Extending shelf life: The ultimate tradeoff
"The tradeoff that companies are always making [is] companies would love to have a product that basically has infinite shelf life … it gives you more time to sell the product," said Schaffner. "The tradeoff is, the quality of food products goes down over time. So what a company is always trying to do is trying to get the maximum possible shelf life but at the same time meet a quality standard [because] they want their customers to have a really high-quality product at the end of the day."
Tradeoffs occur in determining which type of packaging or processing technology to use. For example, freezing can result in a higher-quality product than other methods, but it requires energy and refrigerated storage space. Canning doesn’t require refrigeration, which makes storage more convenient, but so much heat needs to be applied that quality levels can fall.
A company deals with tradeoffs in terms of making subtle quality sacrifices to prevent adding to the massive amount of food waste the country sees each year. A company may extend a code date to include a time when a product may not be at its freshest and crispest but is still safe to eat and nutritionally sound. But by reducing food waste thanks to a longer shelf life, companies can generate savings across various levels of the supply chain.
With a longer shelf life, a company could have more time to transport and sell that product at retail, but how the company goes about extending that shelf life is important, because a longer shelf life can be concerning to consumers.
"Consumers are not really interested in foods that appear to be highly processed," said Schaffner. "That might be a benefit for the company, but that’s never going to be a benefit to the consumer to say, 'Hey, here’s a food product that will look and taste just the same in two years as it does now.' Consumers are suspicious of that."
Up-and-coming shelf life technologies
Researchers are committed to studying and extending shelf-life, including Medallion Labs, which performs shelf life testing to provide actionable data to companies, and the Nestle Research Center, which is currently working on a "shelf-life prediction tool." Here are five other shelf life technologies to keep an eye out for.
High-pressure processing is a way manufacturers can use high pressure instead of heat to maintain foods’ nutrient levels over time while ensuring chemicals don’t enter the food. One company, Sunniva, said this method kept its athletes’ coffee drink product natural while increasing the shelf life from just under a month to four to six months. There are only about 114 high-pressure processing machines in the world.
Modified atmosphere packaging
Modified atmosphere packaging — also known as flushing, protective atmosphere packaging, or reduced oxygen packaging — also extends life without the need of chemical preservatives or stabilizers. It employs a balanced and carefully controlled blend of pure oxygen, carbon dioxide, and nitrogen, contained within a high barrier or permeable package, and the specific respiration levels are tailored for each different product.
In its most basic form, packaging is considered passive and merely serves as a boundary between a product and the outside environment. Another form, called active packaging, means the packaging can respond to a triggering event, either in the product or the environment. Some active packaging technologies include antimicrobial packaging, which slows pathogen growth, and desiccant packaging, which prevents moisture absorption.
Light-based technologies, such as ultraviolet light, pulsed light, and blue LEDs, are being used to break down bacterial cells in food products and sterilizing product surfaces. While these technologies have proven effective, they cannot always penetrate deeply into the product to sterilize the parts of the product that the light cannot touch.
Microwave sterilization process
Through the microwave sterilization process, a product is submerged into pressurized hot water while concurrently being heated with microwaves at a frequency that penetrates food more deeply than consumers’ typical microwave ovens. "This combination eliminates food pathogens and spoilage microorganisms in five to eight minutes and produces foods with much higher quality than conventionally processed products," according to Food Safety News.
In the end, processing and packaging technologies can’t replace the best way to ensure quality throughout a product’s shelf life, which is using quality ingredients from the start.
"For the consumer to get the product that they want with a clean label and a natural product, the food industry [should] build our understanding of ingredient quality, robust formulas and processes, and then packaging," said Sewald. "You put all those things together, and you can have a stable product with a clean label. And that to me is the most exciting thing."