Lactose from Human Milk: Properties, Uses & Lab Guidelines

Lactose from Human Milk is a high-purity disaccharide reagent derived from human breast milk, providing researchers with an authentic biological reference material for infant nutrition science, carbohydrate biochemistry, and gut microbiome studies.

Chemical Name

4-O-β-D-Galactopyranosyl-D-glucose (Lactose)

Source

Human breast milk

Molecular Formula

C₁₂H₂₂O₁₁

Molecular Weight

342.30 g/mol

CAS Number

63-42-3

Product SKU

L1529069

Recommended Storage

Store in a cool, dry place away from light; seal tightly after use

Chemical Identity and Structure

Lactose is a naturally occurring disaccharide composed of D-galactose and D-glucose linked via a β-1,4-glycosidic bond. Its IUPAC designation is 4-O-β-D-galactopyranosyl-D-glucose, with the molecular formula C₁₂H₂₂O₁₁ and a molecular weight of 342.30 g/mol (CAS 63-42-3). Lactose exists in two anomeric forms—α-lactose and β-lactose—that interconvert in aqueous solution through mutarotation, reaching an equilibrium mixture predominantly composed of the β-anomer under ambient conditions.

Lactose from Human Milk (SKU: L1529069) is isolated specifically from human breast milk, distinguishing it from bovine-derived lactose used in food-grade applications. This human-origin sourcing is critical for studies requiring authentic biological matrices, such as infant gut colonization research and human milk biomarker investigations.

Physical and Chemical Properties

Lactose is a white to off-white crystalline powder with a mildly sweet taste relative to sucrose. Key physicochemical properties include:

• Solubility: Soluble in water; the solubility of α-lactose monohydrate in water is approximately 18 g/100 mL at 25 °C, while β-lactose is more soluble (approximately 55 g/100 mL at 25 °C). Practically insoluble in ethanol and most organic solvents.
• Melting point: α-Lactose monohydrate decomposes at approximately 202 °C; anhydrous β-lactose melts at approximately 252 °C.
• Optical rotation: Aqueous solutions exhibit positive optical rotation; the equilibrium value [α]D²⁰ is approximately +55° (mutarotation equilibrium).
• Reducing sugar: Lactose is a reducing disaccharide due to the free anomeric hydroxyl group on the glucose residue and will react positively in Benedict's and Fehling's tests.

Researchers should note that moisture absorption can alter the anomeric ratio; samples should be handled under controlled humidity conditions and, where anomer-specific experiments are required, the appropriate crystalline form (α-monohydrate or anhydrous β) should be specified.

Research Applications

Lactose from Human Milk serves as a versatile reagent across multiple research disciplines:

1. Infant nutrition and formula development: Used as an authenticated reference standard to characterize and quantify lactose in human milk studies, supporting formulation of human milk substitutes that closely mimic natural composition.
2. Gut microbiome research: Lactose is the primary carbohydrate energy source for neonatal gut microbiota, particularly supporting growth of Bifidobacterium and Lactobacillus species. Human-origin lactose is used in in vitro fermentation assays and prebiotic studies.
3. Enzyme activity assays: Serves as a substrate for β-galactosidase (lactase) activity measurements, kinetic studies (Km and Vmax determinations), and inhibitor screening assays.
4. Carbohydrate chemistry and glycobiology: Used as a starting material or reference compound for the synthesis or characterization of human milk oligosaccharides (HMOs) and other galactose-containing glycoconjugates.
5. Analytical method development: Acts as a calibration standard in HPLC, LC-MS, and enzymatic assay methods for lactose quantification in biological and food matrices.

Handling, Storage, and Safety Guidelines

Storage: Store in a tightly sealed container in a cool (15–25 °C), dry environment away from direct light and incompatible materials (strong oxidizing agents). Under recommended conditions, the product maintains integrity for the duration stated on the Certificate of Analysis (CoA). Avoid repeated freeze-thaw cycles for dissolved solutions.

Preparation of stock solutions: Dissolve in ultrapure (Milli-Q) water. To prevent anomeric equilibrium issues in sensitive assays, prepare fresh solutions and allow adequate time for mutarotation equilibrium to be established (typically 30–60 minutes at room temperature) before use, unless a specific anomer is required.

Personal protective equipment (PPE): Although lactose is generally regarded as a low-hazard carbohydrate, standard laboratory practice requires the use of gloves, a lab coat, and safety glasses when handling any chemical reagent. Consult the Safety Data Sheet (SDS) specific to this product for complete hazard information.

Waste disposal: Dispose of lactose solutions in accordance with local institutional and regulatory guidelines for aqueous biological material waste. Do not pour concentrated solutions directly into drainage without dilution and approval from your environmental health and safety (EHS) office.

Quality Assurance and Regulatory Considerations

Purity and characterization: Each lot of Lactose from Human Milk (L1529069) is accompanied by a Certificate of Analysis (CoA) documenting identity confirmation, purity, and relevant physicochemical parameters. Researchers are advised to download the lot-specific CoA from Aladdin Scientific's product page prior to experimental use and to archive it for laboratory records.

Human-origin material considerations: Because this product is derived from human biological material, institutional biosafety committees (IBCs) and institutional review boards (IRBs) may require documentation of source material ethical approval and viral inactivation or testing records. Researchers should consult their institutional biosafety officer before first use.

Regulatory status: This product is supplied for research use only (RUO) and is not intended for diagnostic, therapeutic, or food additive applications without appropriate regulatory review and approval. Use in animal studies may require additional ethical review.

Lot-to-lot consistency: For longitudinal studies or inter-laboratory comparisons, researchers should reserve sufficient material from a single lot or verify consistency across lots using validated analytical methods such as HPLC or NMR spectroscopy.

Frequently asked questions

What distinguishes Lactose from Human Milk from bovine-derived lactose in research applications?

Lactose from Human Milk (L1529069) is isolated specifically from human breast milk, providing an authenticated human-origin reference material. While the chemical structure of lactose (C₁₂H₂₂O₁₁) is identical regardless of species source, human-origin lactose is critical for studies requiring biological authenticity, such as infant gut microbiome research, human milk composition analyses, and investigations of neonatal lactase activity where the matrix context matters.

How should I prepare a lactose solution to ensure anomeric equilibrium before use in enzyme kinetics assays?

Dissolve Lactose from Human Milk in ultrapure water at your desired concentration and allow the solution to equilibrate at room temperature for at least 30–60 minutes with gentle stirring before use. This allows mutarotation to reach the natural α/β equilibrium mixture. If your assay specifically requires a single anomer, the appropriate crystalline form should be selected and freshly dissolved solutions used immediately under controlled conditions.

Is Lactose from Human Milk suitable for use as an HPLC or LC-MS calibration standard?

Yes. High-purity Lactose from Human Milk (L1529069) is well suited as a calibration standard for HPLC and LC-MS quantification of lactose in biological and food-related matrices. Researchers should verify the lot-specific purity from the Certificate of Analysis and prepare gravimetrically accurate standard curves. For mass spectrometric detection, lactose is typically detected as [M+Na]⁺ or [M+NH₄]⁺ adducts under positive ionization mode.

What biosafety precautions are required when working with human-derived lactose?

Although lactose itself is a low-hazard carbohydrate, because this product originates from human biological material, researchers should follow their institution's biosafety policies for human-derived reagents. This typically includes consulting your institutional biosafety officer, verifying that the product has been appropriately processed (e.g., viral testing or inactivation), and maintaining standard laboratory hygiene practices including gloves and lab coat use.

How should unused Lactose from Human Milk be stored to maintain stability?

Store the product as a dry solid in a tightly sealed container at 15–25 °C in a cool, dry location away from light and strong oxidizing agents. Avoid exposure to high humidity, which can promote moisture absorption and alter the anomeric composition. Refer to the lot-specific Certificate of Analysis for the stated shelf life, and do not use the product beyond its expiration date without re-verification of purity.

References

1. Fox PF, McSweeney PLH. Advanced Dairy Chemistry, Volume 3: Lactose, Water, Salts and Minor Constituents. Springer; 2009.
2. Urashima T, Taufik E, Fukuda K, Asakuma S. Recent advances in studies on milk oligosaccharides of cows and other domestic farm animals. Biosci Biotechnol Biochem. 2013;77(3):455-466. doi:10.1271/bbb.120810
3. Kunz C, Rudloff S, Baier W, Klein N, Strobel S. Oligosaccharides in human milk: structural, functional, and metabolic aspects. Annu Rev Nutr. 2000;20:699-722. doi:10.1146/annurev.nutr.20.1.699

Products are supplied for research and development use only. Not for use in humans, animals, diagnosis, or therapy.