“Hi, I would like to mix together the dry ingredients for cakes, breads, cookies, etc. and then put it in individual bags (mylar) for storage purposes or perhaps mason jars. I would like to know if there are any issues with premixing these dry ingredients and longer term storage and what is the longest you could store dry ingredients mixed together before they lose their effectiveness.”
[Ken adds:] Here’s my opinion regarding that question…
The dry ingredients that we’re likely talking about here might include any combination of sugar, salt, baking powder, baking soda, dry milk, possibly powdered eggs, yeast (for breads), and last but not least… flour.
The wet ingredients, although not part of the question, might include any combination of shortening, butter, eggs, milk, water, and vanilla extract (common in many recipes), and other flavorings.
To get to the answer, we need to look at the supposed shelf life of the individual dry ingredients.
The problem with this (for an accurate answer) is that shelf life depends on several factors including method of storage, temperature of storage, and also depends on what the manufacturer considers the threshold of “expiration”.
What does expired truly mean?
That depends too… on the manufacturer and the threshold at which they feel the ideal flavor changes, ‘freshness’, texture changes, appearance changes, or any of a number of other factors which may or may not have anything to do with what YOU might consider to be expired. For example, I’ve safely consumed many things well beyond their expiration dates without issue… I’m not saying that I recommend that, but I’m just saying.
Having said all that, lets have a look…
SUGAR
Commercial white sugar has an indefinite shelf life because it does not support microbial growth. Just store in a moisture-proof environment in a cool, dry place.
I have read mixed reports on the shelf life of brown sugar, with some (manufacturers) indicating an indefinite shelf life (apparently even brown sugar does not support microbial growth), while searching elsewhere may indicate 6 months or a year. I would err on the side of caution and if you need to get your hands on some, simply make your own when needed (see the following note). I’ve also read that apparently you should not vacuum-seal brown sugar because it can develop bacteria when in oxygen-free storage.
Note: You can simply make your own brown sugar when needed, with 1# sugar + 3-oz. molasses (by weight – use a kitchen scale to measure it).
SALT
Salt has an indefinite shelf life. It will clump when moist, but that’s about it.
BAKING POWDER
Though baking powder (and baking soda) aren’t subject to spoilage, both may eventually fail to rise to the occasion as leavening agents for baked goods. Baking powder consists of baking soda, and one or more salts, plus cornstarch to absorb any moisture so a reaction does not take place until a liquid is added to the batter.
Unopened baking powder remains good indefinitely, but once you open a container of baking powder its potency starts to wane (from moisture in the air). So long as it is kept sealed up in a dry container space, it ‘should’ last for quite a long time (indefinite?). It’s the opening and closing and then reopening and closing that allows more and more moisture to be absorbed into it over time to reduce its effectiveness.
BAKING SODA
When a recipe contains baking powder and baking soda, the baking powder does most of the leavening. The baking soda is added to neutralize the acids in the recipe plus to add tenderness and some leavening.
Baking soda has an indefinite shelf life if stored in a sealed container in a cool dry place.
DRY MILK
According to the USDA, powdered milk can be stored indefinitely. To maximize the shelf-life, store your powdered milk in a dry environment (a no-brainer).
POWDERED EGGS
Stored in the absence of oxygen and placed in a cool storage environment, dehydrated powdered eggs have a storage life of 5 to 10 years. Once dried eggs are opened, they need to be used within one to two years.
YEAST
Yeast expires because it’s a micro-organism (a fungus) that eventually dies. The expiration date is a decent estimate of how long the yeast will last, but various conditions (where and how yeast is stored among others) affect how long it will live. Yeast does expire . Yeast will last longer than the date printed on the packet if it is kept in the refrigerator. It will last longer in the freezer (reportedly up to 5 years for some).
An unopened package of instant yeast typically has a shelf life of up to two years, and up to 5 years in the freezer. If the package is opened and combined in a dry environment with other DRY ingredients, and then kept dry by proper storage, there is no reason that the shelf life should remain as posted on the package.
FLOUR
Here’s the issue… flour, the most important ingredient, has a somewhat short shelf life.
Unopened bags of white flour normally stay fresh for up to a year. As the flour ages, and depending on storage conditions, the flour will eventually develop a bad taste and then go rancid (especially wheat flour); it will taste like it smells. It may even develop creepy crawlies depending on storage.
We have consumed processed white flour that has been several years old without issue, although we try to rotate what we have, and more importantly we mostly grind/mill our own when needed.
Note: Wheat (berries) is so much better to deal with because you can grind it as you go, not lose the nutritional value, and it will store for decades if kept properly (naturally preserved in it’s shell – the bran). But this doesn’t relate to the question posed above…
So generally speaking, I would estimate several years shelf life for white processed flour before the possibility of developing an off-taste, if stored well.
My Final Answer
The limiting factors include the flour (~ 2 years), powdered eggs if used (~ 2 years), and instant yeast if used (~ 2 years).
Since flour is used in ALL of the recipes for cakes, breads, or cookies, the approximate 2 year shelf life may be the underlying limit for premixing the dry ingredients and keeping them in individual bags or jars.
You could obtain longer shelf life by vacuum sealing or using oxygen absorbers in a sealed environment…
I’ve read this regarding vacuum-sealed flour:
“It will also store much longer if vacuum-sealed, BUT, it needs to be vacuum-sealed in a jar or a canister where it remains free-flowing, rather than in a FoodSaver bag where it will get packed tightly. There is moisture in flour, and when it’s packed tight in a FoodSaver bag it can develop a musty smell, so the FoodSaver people suggest vacuum-sealing it in a jar or canister.”
It may become an expensive proposition to buy special vacuum-seal jars or canisters for this purpose, if storing ahead lots of premixed units.
The bottom line is that it appears you can store premixed dry ingredients for cakes and breads for a few years in a dry environment and dry packaging at room temperature, before you may experience “off” flavors from the flour. The solution is to practice good food rotation. Store what you eat, and eat what you store…
If anyone has something to add here, or experience with consuming old flour, please comment and let the rest of us know…