Two cookies are sitting on the counter in the same kitchen. They are in the same container. One cookie becomes soft and the other cookie becomes hard as a rock. Both cookies are stale. This happens for very different reasons.
If you understand why this is happening you will know what kind of container each cookie needs. You will also know why using the wrong container makes things worse.
The Science Is Simple Once You See It
The way cookies become stale is actually pretty simple. Cookies become stale when moisture moves around. The direction that the moisture moves is what makes a cookie crispy or chewy.
Crispy cookies like shortbread or biscotti are baked for a long time and they have very little moisture when they come out of the oven. The problem they have is that the air around them is humid and this humidity makes them soft. If you leave a crispy biscotti on a plate in a humid kitchen it will become soft in a few hours.
Chewy cookies are the opposite. They are dense and they have a lot of moisture inside. This moisture is what makes them chewy. If you leave them out in the dry air they will lose this moisture and become hard. A chocolate chip cookie that is fresh will become harder if you do not store it properly.
This is the same thing happening in opposite directions. That is why crispy cookies and chewy cookies need different containers.
What Each Cookie Actually Needs
Crispy cookies need a container that keeps the moisture out. Any container that is airtight will work well in a normal kitchen. If your kitchen is very humid you can add a special packet to the container that absorbs moisture.
Chewy cookies need a container that keeps the moisture inside. The container needs to have a good seal. A container with a seal that pushes down on the rim is better than a container with a loose lid. You can also put a slice of bread or a special disc in the container to help keep the moisture inside.
The Mixing Problem
If you put a crispy cookie and a chewy cookie in the same container they will ruin each other. The chewy cookie will release moisture and the crispy cookie will absorb it. In one day the crispy cookie will become soft and the chewy cookie will become dry. Both cookies will become stale faster than if you stored them separately.
You should store different types of cookies in separate containers. This might seem like more work but it is the best way to keep your cookies fresh.
Freshness Windows When Stored Correctly
- Crispy cookies in an airtight container: 2 to 3 weeks at room temperature
- Chewy cookies in an airtight container: 4 to 5 days at room temperature
- Mixed in the same container: both become stale in just 2 days
The difference is big. Crispy cookies can stay fresh for a long time because they have very little moisture. Chewy cookies need a good seal from the start.
The Container Decision
For crispy cookies you can use any airtight container. For chewy cookies the seal is very important. A container with a seal that compresses against the rim is better than a container with a loose lid. If you bake both types of cookies often the simplest solution is to have two containers.
[…] won’t get hard, and the moisture in the cookie doesn’t move around too fast, so an airtight container can easily hold it […]