Storing tea can be very simple. If you keep your tea in an airtight container and then store your container in a dark, cool, dry place free from strong odors, you will likely consume it before any degradation in aroma or taste occurs. However, tea is constantly deteriorating, very slowly, as soon as the leaves are picked off the plant.
When we talk about a tea deteriorating, we are mostly talking about oxidation. Teas that are prevented from oxidizing during production and teas that are not heavily oxidized during processing will continue to oxidize over time. Because these teas are typically prized for their vitality and lack of oxidation, this ongoing oxidation is considered a harmful form of deterioration. This is the case for green teas, yellow teas and some white teas.
For teas that are allowed to oxidize during production, especially those that are purposely heavily oxidized, there is much less potential for oxidation to continue. If it does, further oxidation of these teas is much harder to notice in the cup. This is the case for black teas and heavily oxidized wulongs.
Storing Tea to be Aged
What about aged teas? Isn’t that a special case for tea storage? In short, yes. The goal of aging a tea is to allow the tea to change over time in order to increase its palatability. The way in which these teas are aged depends on how we store them; aging tea is synonymous with storing tea.
Hermetic Seal Storage
When teas are stored in an airtight vessel, the ambient oxygen left in the container allows the tea to slowly oxidize over time. Wulong teas are typically sealed in a container with an airtight seal, and they are often left to age for many years.
Non-Hermetic Seal Aging
Puer (and other fermented teas) are not typically shielded from moisture. Instead, a controlled level of moisture is employed to influence the aging during storage. In this case, over time, the tea leaves undergo a combination of fermentation and oxidation. In fact, the raw leaves that become Puer are often fixed at a lower temperature so that the oxidative enzymes within the leaves are not fully denatured. This method of fixing allows for further oxidation at a later stage.
Storing All Other (Non-Aged) Teas
So if we’re not actively trying to age our tea and we just want to preserve the fresh nature of it, what must we do? There are six laws of tea storage that will help you:
1. Tea must be kept free from oxygen
Tea leaves continue to oxidize over time with exposure to oxygen. Even when stored in an airtight vessel, some air remains in between the leaves and at the top of the vessel; airtight does not mean air-free.
Some teas come prepackaged in vacuum sealed bags; it is typical for ball-style wulongs to be packaged in this manner. Vacuum sealing is a great way to ensure that the tea leaves are safe for a long time. However, this method can only be used for strong leaves. Vacuum sealing a delicate leaf will crush it! This is why ball-style wulongs are a perfect candidate for vacuum sealing.
For teas that are more delicate, the packages may be flushed with nitrogen while they are sealed. This way, the leaves are not exposed to oxygen and do not degrade over time.
Another option is to use oxygen-absorbing packets that usually contain iron and salt. When placed in an airtight vessel, the remaining oxygen oxidizes the iron, creating rust. Once all of the iron has oxidized, the oxygen absorbing packet can no longer absorb oxygen. These packets are really only good for long term storage; opening and closing the container will keep letting oxygen in, rendering the packet useless after a short time.
2. Tea must be kept free from heat
Low-level heat speeds up oxidation, while high levels of heat prevent oxidation. Some delicate green and yellow teas are best if stored in the freezer or refrigerator; the cold temperatures dramatically slow down oxidation reactions. However, this must be done properly to avoid condensation on the leaves.
It is advisable to re-package the tea into small packets so that your supply overall will stay fresher for longer. Each packet should be used within a week after opening. Before you put the packages in the freezer, squeeze as much air out as possible; any remaining air will condense and cause moisture to develop on the leaf surface. The most important thing to remember when using cold storage for teas is that when you remove a packet from the freezer or refrigerator, do not open it until it has reached room temperature. This will prevent any condensation from occurring as the leaves come up to room temperature.
3. Tea must be kept away from light
Much of what is written on the effects that light has on dry tea leaves is based on anecdotal evidence; this topic hasn’t been studied in depth. We do know that light-induced damage gives tea a metallic flavor. Nigel Melican believes that “light-induced changes in dry teas can occur through photodegradation” which is a blanket term for any light-induced reaction that degrades the quality of tea. Nigel suspects a combination of theaflavin polymerization, chlorophyll conversion to pheophytins and photo-oxidative changes to theaflavins and residual catechins are at play here. While tea aficionados are still figuring out exactly what chemical changes are occurring in the leaves, it’s wise to keep your tea free from light.
4. Tea must be kept away from strong odors
Tea leaves will absorb the scents of their surroundings. This is beneficial in the production of scented teas, such as jasmine; the leaves are stored in close proximity to jasmine blossoms, resulting in a jasmine scented tea. However, this same quality of tea can be detrimental should your tea leaves come in contact with unpleasant odors. This not only means that you should store your tea storage vessels in a place free from strong smells, it also means that whatever you are storing your tea in must not have a strong smell itself. Certain wooden containers, airtight tins with strong-smelling rubber seals, and plastic containers can all leave your tea with a disagreeable aroma and taste.
5. Tea must be kept away from moisture
It’s no secret that tea leaves release their flavor when exposed to moisture. Because of this, you really don’t want your tea to “steep” until you steep it for drinking. Keeping your tea storage free of moisture isn’t as simple as keeping the leaves away from visible liquids. Tea is hygroscopic, meaning that it will absorb moisture from the air. An airtight storage container is the simplest way to block out moisture.
6. Tea is best when stored in bulk
This is basically a combination of the first and fourth rules above, but it is worth mentioning. A near empty airtight vessel with a tiny bit of tea in the bottom will deteriorate faster than an airtight vessel completely full of tea. To keep your tea the freshest, fill your storage vessel as much as possible, shake it to let the tea settle, and then fill it some more. The more tea you can keep in an enclosed space, the less oxygen there will be in that space. Less air will make it harder for the tea to absorb the smells of its surroundings. This concept is of utmost importance when aging Puer and other fermented teas; you want a closet that smells like tea, not a few teas that smell like your closet.
Tea Storage Tips
Teas that are less oxidized (greens, yellows and whites) degrade more quickly than teas that are more oxidized (wulongs and blacks).
The more broken the leaves are, the higher the surface area in contact with air. More broken leaves will deteriorate faster.
When taking tea from its original package and putting it into your own container, always label it clearly with the type of tea, style of tea, where you purchased it and when. I can’t count how many times I’ve discovered a random tin of “miscellaneous tea” around the house. This is also helpful for going back through your collection and seeing how your tastes change over time.
If you buy tea in bulk for personal consumption, consider repackaging it into small amounts that can be unsealed as you go. Many tea merchants sell their tea in foil-lined zip seal bags; these can come in handy because they are available in many sizes and are easy to label.