If you’re considering starting a food company and no one has successfully convinced you otherwise, then you might be wondering how to make your product food-safe, and once safe, how to determine the "best by" date. Shelf life is dictated by both food safety and sensory attributes.
Microbial Shelf Life and Food Safety
Microbial shelf life is the highest stakes, so we'll talk about it first. Your product may taste amazing, but if microbes are climbing their way up the ingredient deck and posing bodily harm to your consumer base, you need to put down those "best by" stickers and make some changes.
Pathogens vs. Spoilage Microbes.
There are two general categories of microbes that are relevant to our food: pathogens and spoilage organisms. Pathogens are microbes that can make people sick, for instance C. botulinum, Listeria, and Salmonella. These are the non-negotiable, zero tolerance microbes of your recall nightmares. They shouldn’t be on any food that is ready-to-eat, and every product should have some kind of intervention or control measure--pasteurization, preservatives, pH, alcohol, etc.--in place to eliminate pathogens during production. Spoilage microbes, on the other hand, generally don’t cause illness, but they can make food unappealing. These are the microbes that curdle your milk, mold your bread, and ferment your juice. Spoilage microbes can be present at low levels after production and grow slowly until they cause an issue, thus ending your microbial shelf life.
Shelf-Stable vs. Perishable Products.
Shelf-stable products are products that have been processed in such a way as to inhibit microbial growth at ambient temperature. The processing necessary to achieve shelf stability is product dependent. Crackers, cereal, nut butters, and dried fruit, for instance, are water-activity controlled. The amount of unbound water available in these products is insufficient to feed and support microbial growth, so absent any contamination or faulty packaging, these products will be free from microbes for as long as those packages remain sealed. Certain pasteurized, sealed liquids can also be shelf-stable because they were heated to temperatures that kill microbes and were packaged in a manner that did not allow for the introduction of new microbes. Achieving shelf stability requires food science and safety expertise, so best to consult knowledgable product developers (i.e., us) or a process authority to ensure you're doing it right. The good news for shelf-stable products, as long as they're not contaminated and the packaging integrity is intact, is that they are food-safe and free from spoilage microbes indefinitely. Those crackers you bought five years ago might be stale and those peanuts you brought home from a baseball game pre-COVID might be rancid, but they aren't going to hurt you. This also means that for shelf-stable products, food safety is not going to determine your "best by" date. For these products, we'll need to focus on sensory characteristics (keep reading below for more!).
Perishable products, however, don't exist in a world of microbial stasis. Instead, over time, spoilage microbes will gain a foothold in these products and grow exponentially. This is why your milk curdles and your yogurt molds in a matter of days after opening. Perishable products are also subjected to control measures like pasteurization, including high-pressure pasteurization, to eliminate pathogens, but the amount of unbound water present in these products is sufficient to provide a veritable wonderland for spoilage microbes. Refrigeration temperatures and package seals slow them down but can't stop them. As a consequence, microbes do typically dictate the "best by" date for perishable products. Most brands selling perishable goods opt to send samples out to a third party microbiology lab to watch how those microbes grow and set a spoilage shelf life accordingly. If you work with us, we'll help manage this process for you. Otherwise you can reach out to those labs and coordinate with them directly.
The Sensory Side
Ok, you've ensured your product is pathogen-free and saved the world from Listeria and Salmonella. While your product won't hurt anyone, we haven't answered the question of what its ultimate shelf life will be. After controlling microbes, we turn to sensory attributes to dictate shelf life. Sensory shelf life is the point at which the taste, texture, aroma, or visual qualities of the product deteriorate to the point where you no longer want a consumer to experience it, and thus, you no longer want to sell it.
For perishable products, as we mention above, the shelf life will likely be dictated by how long it takes for spoilage microbes to ravage your product. It is theoretically possible that a perishable product may reach the end of its sensory shelf life before being taken over by spoilage microbes, but it's more typical for the microbial shelf life to be shorter than the sensory for perishable products.
For shelf-stable products, since the microbes aren't in charge, the sensory attributes of your product will drive shelf life. Determining the point at which you no longer wish a consumer to interact with your product is a subjective business decision. You'll want to weigh the sensory aspects against the business drivers of inventory management and distributor requirements. There are many ways to forecast a ballpark sensory shelf life based on the category of product, the ingredients and flavor profiles, and even accelerated testing in some cases, but there is no substitute for real-time data collected from actual product samples from a production run. We would expect most shelf-stable products to have a sensory shelf life of between three and eighteen months, depending on the product and packaging, but your developer can guide you to selecting a more narrow range that's suitable for your particular product. For initial runs, most brands opt to start by printing a conservative, reasonable shelf life estimate on their packaging, and slowly extending that shelf life out further and further for subsequent production runs as they gather more real-time data on their product.