Below is a list of “thermos usage taboos.” These liquids are strongly discouraged from being stored long-term in stainless steel thermos bottles:

【Absolutely Do Not Fill】⚠️⚠️⚠️

1. Acidic beverages (fruit juices, carbonated drinks, plum soup, etc.)

· Reason: Stainless steel is highly susceptible to strong acids. Acidic liquids like fruit juices (orange, apple), carbonated drinks (cola, soda), vinegar, and plum soup can corrode the stainless steel inner lining. Prolonged exposure may lead to:

→ Inner lining damage: Destruction of the passivation layer, releasing heavy metals (chromium, nickel, etc.). While food-grade stainless steel is highly corrosion-resistant, prolonged contact with strong acids still poses risks.

→ Beverage spoilage: Drinks reacting with metal may alter taste or produce harmful substances.

·Recommendation: If chilling acidic beverages, minimize storage time (no more than a few hours) and clean promptly. Preferably use thermoses with glass liners.

2. Protein-rich beverages like milk and soy milk

·Reason: Thermoses provide a warm, sealed environment ideal for bacterial growth.

→ Rapid spoilage: Milk and soy milk spoil quickly at elevated temperatures (20-40°C), potentially causing diarrhea and abdominal pain if consumed.

→ Difficult cleaning: Proteins adhere to inner walls, causing odors and making thorough cleaning challenging.

·Recommendation: If carrying is necessary, consume within 2-3 hours and clean immediately afterward. Ideally, do not exceed 1 hour.

3. Tea

· Reason:

→ Flavor degradation: Prolonged steeping in high temperatures causes excessive extraction of tea polyphenols and tannins, resulting in bitter taste, darkened color, and diminished aroma.

→ Stubborn tea stains: Residue forms stubborn deposits that are difficult to clean.

→ Potential corrosion: While short-term effects are minimal, tea's acidic nature poses a slight risk of corrosion with prolonged immersion.

·Recommendation: Use a tea strainer to separate leaves from water, or consume brewed tea promptly. Avoid prolonged storage (e.g., over half a day) in thermoses.

4. Herbal Decoctions

·Reason: Herbal ingredients are complex, typically containing alkaloids, organic acids, and other compounds.

→Chemical Reactions: These substances readily react with stainless steel liners, potentially producing unknown harmful substances.

→Corrosiveness: Certain acidic herbs may corrode the inner lining.

·Recommendation: Never store herbal decoctions in stainless steel thermoses. Use glass or ceramic containers instead.

5. Salt Solutions (Saline, Concentrated Broths, etc.)

·Reason: Highly concentrated saline solutions (e.g., physiological saline) or very salty broths contain chloride ions that may cause pitting corrosion (localized corrosion) in stainless steel, damaging the inner lining's protective layer.

·Recommendation: Avoid storing such liquids.