For starters, the health-level can depend on anything from sourcing of ingredients and their quality, to any potential degradation of the material used as the storage container (bottle, can, etc.), to manufacturing practices that ensure the healthiest form of coffee. I’d like to analyze the different components of this question and break down how food-manufacturers decide on whether Ready-To-Drink Coffee is either bottled or canned, and this can help you determine which beverage-packaging-option is healthier for you when you notice options in your local grocery store.
Unlike hot coffee that is served immediately after brewing at coffee shops in either disposable or reuseable cups, when you seal a container from oxygen for any period of time, it has to be stored with precautions in-mind to avoid any potentially hazardous bacteria. To ensure safe manufacturing practices with organic matter, such as coffee or other low-acid foods (pH great than 4.6), there are a few options to choose from to treat the beverage aseptically before sealing - these steps are known as "kill-steps." Depending on the container chosen to store the beverage (metal, glass, plastic, Tetra Pak, etc.), there are different options available to perform these kill-steps, which would eliminate the potentially hazardous growth of bacteria - the most dangerous bacteria that can grow in sealed containers is known as C. botulinum, which is one of the most potent toxins known to mankind and can be lethal.
What you need to know about botulism: ~1,000 cases reported yearly in the world (0.00001% chance of getting it) and of those, only about 7.5% that are fatal. So the odds of this happening to you are 1 in 100 million, which is similar to the odds of winning the lottery. Simply put, all food manufacturers and Health Departments across the globe are familiar with this bacteria and create their entire production infrastructure around avoiding it so nothing to worry about, just something to keep in mind as I explain the different container options chosen by the manufacturer.
The most common kill-steps used to treat coffee are either micron-filtration, UHT (ultra-high temperature), HPP (high-pressure processing), pasteurization, flash-pasteurization, retorting, or a combination of any of them. However, some of these steps also ruin the product quality in exchange for a longer shelf life. If the manufacturer uses HPP (plastic containers only), retort (canned container only), or UHT (Tetra Pak or other soft materials), the beverage can be sealed and kept in room temperatures for up to 2 years without risk of contamination or bacterial growth. Otherwise, if the coffee is micron-filtred, pasteurized, or flash-pasteurized, the beverage can be kept in any type of container (glass, metal, plastic, etc.) for up to 6 months, but has to REMAIN REFRIGERATED the entire time. Refrigeration is another way to slow down the potential growth of harmful bacteria, and can be utilized to maintain high-quality flavors of the product. Of these kill-steps, the ones that require refrigeration to keep the coffee in its most natural form, also keep the highest level of antioxidants present, rather than burning them off through HPP, UHT, or retorting.
Based on best practices and a variety of factors in the food-manufacturing industry, if the product has a longer shelf life and can be stored at room temperature = larger production runs since you have more time to sell the product, which means lower cost per unit to manufacture. The same idea works similarly in other manufacturing practices - for example, clothes are generally mass-produced as it’s less expensive per unit when done in larger volumes. The main difference with food is you'd have to throw away everything after expiration so forecasting has to be done much more intelligently.
The downside if you use a kill-step that increases shelf life/enables room-temp storage, you are very likely to burn off the desirable flavor-notes in high-quality coffee so you are sacrificing quality to reduce costs by means of having larger output. To take this a step further, if you are going to burn off those delicious and natural flavors of the coffee, you might as well also use lower quality coffee as an ingredient so it’ll be less expensive with a similar outcome in flavor after the aseptic treatment.
Packaging also varies in costs with glass being the most expensive for both purchasing and distribution because of its weight and potential breakage. The next most expensive options are cans, Tetra Pak, and finally plastic containers.
Another variable in ingredient sourcing, which depend on the certification the coffee comes with. Coffee can be organic, Rainforest Alliance, etc. and since this is the main ingredient in the beverage, these are
So if HPP, retort, or UHT are used as kill-steps, it is likely to also manufacture using lower quality coffee, which has a correlation to a less healthy beverage overall, especially if the ingredients are sourced poorly. If you are using these methods, the only packaging option available to you would have to be between cans, plastic, or Tetra Paks. Important note - glass wouldn’t work with any of these kill steps!
The other kill-step options, which are micron-filtration, pasteurization, or flash pasteurization can be stored in any container, including glass, but will have to be remain refrigerated until consumption, which keeps flavors in their prime for up to 6 months. If one of the last 3 options are used, higher quality beans may also go hand-in-hand as the manufacturer is already paying a premium for the refrigerated supply chain and is most likely using this kill-step as they want to have a higher-quality product.
Additionally, refrigerated distribution with a relatively short shelf life = small batch production runs = higher cost per unit.
Tying it all back together:
Glass will always be the most expensive packaging option, especially with coffee beverages since it would require cold storage, heavy shipping, and short shelf life. The packaging, manufacturing process, distribution option, and storage make up nearly the entire cost of the product. The ingredients generally account for less than 10% of the total cost to the consumer of the product! However, because food and beverage manufacturing operate on such laser-thin margins, reducing costs (even less than 1% total difference) wherever possible can be the difference between an operational business and a bankrupt one.
The healthiest container would be the beverage that not only sourced higher quality ingredients, but also stores them properly. Plastic, for example, can leach chemicals in heated environments, which are unhealthy and can also alternate the flavor of the beverage. If this is found as a shelf-stable item, it would likely be considered the least healthy option since it means it was treated with a HPP, retort, and UHT, which could correlate to it also using lower quality ingredients.
Cans can be retorted, pasteurized, flash-pasteurized or micron-filtered. So if the can claims “Perishable" or "Keep Refrigerated” it means cold storage is necessary, which brings us back to the correlation of potentially higher quality ingredients. If it retorted and shelf-stable, it likely means that it is mass produced and contains lower quality ingredients, which in turn could be less healthy.
So to answer your question, based on the correlations and assumptions made, the probability of bottled iced coffee being healthier than canned iced coffee is higher. If you see a glass bottled coffee beverage that is refrigerated, has Rainforest Alliance, Organic, and other certifications, you are probably investing your money wisely.
At Dripdash, we source the highest quality ingredients for both our canned and bottled beverages, which go through the same flash-pasteurization process and have a 100-day refrigerated shelf life to maintain the high quality flavors. We choose to use cans for our dairy-free milk coffee (Oatmilk Maple Lavender Coffee) because the natural ingredients separate and it doesn’t look pretty until shaken, and we use glass bottles for our Kyoto Drip Coffee, which is the first and only Ready-to-Drink coffee served in Michelin Star restaurants. We pride ourselves in our quality and being the healthiest ready-to-drink coffee option available in stores and online.