Improper formula preparation can lead to nutritional imbalances at best, and bacterial infection risks at worst. This guide helps you understand the scientific methods for preparing and storing infant formula.

Formula Preparation Seems Simple, But These Details Affect Your Baby's Safety

Improper formula preparation can lead to nutritional imbalances at best, and bacterial infection risks at worst. This guide helps you understand the scientific methods for preparing and storing infant formula.

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1. Core Requirements for Formula Preparation

Water Temperature

Why not use cold water:

• Formula powder won't fully dissolve
• Fat globules distribute unevenly
• Cannot kill potentially present bacteria

Why not use boiling water / high-temperature water:

• Destroys heat-sensitive nutrients (Vitamin C, some prebiotics)
• Causes protein denaturation
• Kills probiotics (if present)

Recommended Temperature:

• Standard formula: Around 70°C (no lower than 70°C)
• Formula with probiotics: Follow product instructions (some require no higher than 40°C)

Key Point: 70°C is the temperature recommended by the World Health Organization (WHO) for formula preparation. It kills Cronobacter sakazakii (a pathogen that can cause neonatal meningitis and has been known to contaminate formula).

How to achieve it:

• Boil water
• Let it cool to 70°C (typically takes about 10-15 minutes)
• Or use a temperature-controlled kettle (set directly to 70°C)

Mixing Order

Correct Order: Add water first, then add powder.

Adding powder first and then water is incorrect and leads to:

• Powder settling at the bottom, resulting in uneven dissolution
• The actual water-to-powder ratio deviating from the standard (making the formula too concentrated)

Steps:

1. Measure the correct amount of hot water (70°C) into the bottle
2. Measure the correct amount of powder using the scoop provided inside the can (do not pack it down)
3. Shake or swirl to dissolve
4. Cool to a suitable drinking temperature (around 40°C, test on the inside of your wrist)

Using the Scoop

Common Mistake: Packing the scoop.

• The scoop should be leveled off (use the built-in scraper on the can or a clean knife to level off excess powder)
• Do not pack it down (packing adds too much powder)
• Do not use a heaping scoop (a heaping scoop adds too little powder)

Scoop Sizes Vary by Brand:

• When switching formula brands, you must use the scoop from the new brand
• The weight of one scoop can differ between brands

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2. The Importance of the Correct Mixing Ratio

Dangers of Over-Concentration and Under-Concentration

Over-Concentrated (Too Much Powder):

• Osmolality is too high, increasing kidney workload
• Excessive protein and minerals
• Long-term use can affect kidney function
• Baby's urine may appear darker yellow

Under-Concentrated (Too Little Powder):

• Insufficient nutrition
• Inadequate calorie intake, causing the baby to get hungry quickly

Standard Ratio: Strictly follow the instructions on the can (typically 1 scoop per 30ml of water, but this varies by brand).

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3. Formula Storage Times

Storage Rules for Prepared Formula

Condition	Storage Time
Room temperature (below 25°C)	No more than 2 hours
Refrigerated (2-4°C)	No more than 24 hours
Freezing (not recommended)	Freezing prepared formula is not advised

Important:

• Any formula left over after the baby has started drinking must be finished or discarded within 1 hour (due to saliva contamination).
• Do not re-refrigerate formula that has already been warmed and then reheat it (multiple temperature changes increase bacterial risk).

Storage of Opened Formula Powder

Container Type	After Opening
Metal can	Seal tightly, store in a dry place, use within 4 weeks
Cardboard box / Pouch	Transfer to an airtight container, use within 4 weeks

Prohibited Practices:

• Do not store in the refrigerator (cold storage causes moisture absorption and clumping; taking it out of the freezer causes large temperature fluctuations).
• Do not expose to direct sunlight.
• Keep the scoop dry (do not use a wet scoop to take powder).

Unopened Formula

• Follow the expiration date on the package.
• Store in a cool, dry place (avoid high heat, humidity, and direct sunlight).
• Refrigeration is not required.

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4. Bottle Cleaning and Sterilization

Cleaning Requirements

Clean immediately after each use:

• Rinse with warm water and a bottle brush (use a dedicated bottle brush).
• Focus on cleaning the inside and outside of the nipple and the bottom of the bottle.
• Cleaning solution: Use a dedicated bottle cleaning solution (or a fragrance-free, colorless dish soap).

Do not: Use a dishwasher (high heat can damage silicone nipples and standard non-heat-resistant glass bottles).

Sterilization Methods

Boiling Sterilization:

• Glass bottles: Fully submerge, boil for 5 minutes after the water starts boiling.
• PP (Polypropylene) bottles: Place in cold water, bring to a boil, and remove after 3 minutes (do not place them in already boiling water).
• Silicone nipples: Same treatment as PP bottles (3 minutes).

Steam Sterilizer:

• Convenient and designed specifically for bottles.
• Keep covered after sterilization.
• Recommended option.

UV Sterilizer:

• No heat source, suitable for heat-sensitive nipples.
• Ensure the UV light reaches all internal surfaces.

Sterilization Frequency:

• 0-4 months old: Sterilize after every use.
• After 4 months old: Sterilize at least once a day (or as needed).

Post-Sterilization Handling

• Allow items to air dry naturally as soon as possible after sterilization (do not wipe with a cloth).
• Store in a clean, covered container (do not leave them out in the open).
• If a sterilized bottle has not been used for more than 24 hours, it needs to be re-sterilized.

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5. Formula Brands and Standards

Logic Behind Formula Stages

Stage	Age	Nutritional Characteristics
Stage 1	0-6 months	Mimics breast milk, lower protein content
Stage 2	6-12 months	Increased iron, calcium, and other trace elements
Stage 3	12 months - 3 years	Closer to toddler food, higher protein and calcium

Important: Babies under 6 months must strictly be fed the appropriate stage (Stage 1). Do not feed them Stage 2 or Stage 3 formula.

Differences Between Domestic and International Formulas

European Formula (e.g., from Germany, UK):

• Regulated by strict EU infant formula regulations.
• Typically does not contain added vanillin (artificial flavoring).
• Some may not contain DHA (pending qualification certification).

Domestic Formula (e.g., from China):

• Regulated by national food safety standards.
• Products from major manufacturers have reliable safety records.
• Usually contains DHA/ARA.

Selection Advice: Purchase from official channels (to avoid counterfeits). Do not blindly pursue parallel imports from overseas (due to batch management risks).

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6. Common Questions

Bubbles in Prepared Formula

• Bubbles are a normal result of the fat and protein in the formula.
• They are created during shaking.
• Wait 1-2 minutes before feeding to let the foam settle.
• Or gently swirl the bottle (do not shake vigorously).

Abnormal Formula Color or Smell

• Formula should be a uniform pale yellow color (shade may vary slightly by brand).
• It should have no off-odors (rancid, musty, or moldy smells are abnormal).
• Clumping: Indicates moisture absorption. Check your storage method. If clumps are severe, discard the formula.

Baby Refuses Formula

• When switching from breast milk to formula, babies may need 1-2 weeks to adapt.
• Try mixing breast milk and formula (gradually increasing the proportion of formula).
• Control the temperature to be close to body temperature (38-39°C).
• Choose the correct nipple flow rate (0-3 months: slow flow nipple).

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7. Summary

Three Principles of Preparation:

1. Water temperature 70°C (for safety), final drinking temperature 40°C.
2. Add water first, then powder. Follow the ratio strictly.
3. Level the scoop, do not pack it down.

Storage Principles:

• Prepared formula at room temperature: use within 2 hours.
• Refrigerated: no more than 24 hours.
• Leftover formula from a feeding: handle within 1 hour.

Safety First:

• Clean bottles after every use, sterilize regularly.
• Do not use a wet scoop to take powder.
• Use opened formula within 4 weeks.