Hello Lykkers! Thermoses are a convenient and portable solution for keeping your beverages hot or cold, but not all liquids are suitable for storage in them.

To make sure your thermos works efficiently, lasts longer, and keeps your drinks safe and fresh, it's important to understand what should never go inside. Here's a breakdown of what you should never put in a thermos!

1. Dairy-Based Drinks: Risk of Spoilage

Dairy-based beverages like milk, cream, or smoothies are best avoided in bottle thermoses. Dairy products are perishable and can spoil if not kept at the right temperature. While thermoses are good at maintaining warmth or coldness, they can't keep milk and cream cold enough to prevent bacterial growth for extended periods.

Storing these in your thermos can lead to unpleasant odors, curdling, and potential food-borne illness. If you must carry dairy, consider using an insulated container designed to maintain a safe, cold temperature, or add dairy at the time of consumption.

2. Carbonated Beverages: Pressure Build-Up

Carbonated drinks, such as soda or sparkling water, should not be stored in a bottle thermos. The carbonation in these drinks creates pressure inside the thermos, and the sealed lid can trap this gas. When you open the thermos, the pressure can cause the beverage to foam over or fizz uncontrollably, making a mess. In extreme cases, the pressure can even cause the thermos to malfunction.

3. Fresh Fruit Juices: Oxidation and Fermentation

Fresh fruit juices, especially those made from home or bought without preservatives, should not be stored in a bottle thermos for long periods. Fruit juices, when exposed to air, oxidize quickly and ferment. This causes the juice to spoil and develop off flavors, making it unpleasant to drink. Even if sealed in a thermos, the juice will not stay fresh as it would in a refrigerator. To maintain freshness, drink juices right after preparing or use a container designed to preserve freshness for longer periods.

4. Sweetened Drinks: Sticky Residues

Sweetened beverages, such as hot chocolate or coffee with sugar, should be avoided in a bottle thermos. Over time, the sugar content can leave behind sticky residues inside the thermos, making it difficult to clean thoroughly. The buildup of sugar can affect the seals, making the thermos less effective at maintaining the desired temperature. For easier maintenance, keep sugary drinks out of your thermos, and if you need to carry something sweet, drink it fresh instead of storing it for hours.

5. Tea with Milk: Curdling and Spoiling

Storing tea with milk in a bottle thermos is not a good idea. The heat inside the thermos can cause the milk to curdle, especially if it’s stored for several hours. This not only ruins the taste and texture of the tea but also makes for a very unpleasant drinking experience. To avoid this, store the tea and milk separately, and combine them when you're ready to drink. This will ensure your beverage stays smooth and enjoyable.

6. Oily or Fatty Liquids: Stains and Residue

Oily beverages, such as certain types of creamy soups or fatty broths, should never be stored in a bottle thermos. These liquids contain oils and fats that can leave behind greasy residue inside the thermos, making it difficult to clean. The oils can also degrade the seals and insulation over time, compromising the thermos's performance. To avoid this, stick to water-based drinks or choose a thermos specifically designed for food if you're looking to store liquid meals.

7. Hot Liquids Above a Safe Temperature: Burn Risks

Bottle thermoses are designed to keep liquids hot, but it’s important not to put liquids in that are too hot to begin with. Extremely high-temperature liquids, such as boiling water or scalding coffee, can make the thermos uncomfortable to handle and may cause burns when opened. It's essential to allow your drink to cool slightly before transferring it into your thermos to ensure it’s safe to handle and doesn’t damage the thermos itself.

To keep your bottle thermos in top condition and your beverages safe, choose your drinks wisely. Stick to water, plain tea, or coffee (without milk or sugar) for the best experience. If you’re planning to carry anything more delicate, like dairy or sugary drinks, ensure you use the appropriate container that can maintain the right temperature and prevent spoilage.

With avoiding the above liquids, you’ll enjoy a more efficient thermos and fresher beverages every time!