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Views: 0 Author: Site Editor Publish Time: 2026-08-06 Origin: Site
Lactic acid (C₃H₆O₃), also known as 2-hydroxypropanoic acid, is an organic acid that occurs naturally through the fermentation of sugars by lactic acid bacteria (LAB). It was first isolated from sour milk in 1780 by Swedish chemist Carl Wilhelm Scheele — which is how it got its name, derived from the Latin word lac meaning "milk."
Today, lactic acid is produced on an industrial scale through microbial fermentation using renewable carbohydrate sources such as corn starch, sugarcane, or cassava. It exists in two optical isomers: L-(+)-lactic acid and D-(-)-lactic acid, with the L-form being the predominant type used in food and industrial applications.
As a GRAS (Generally Recognized As Safe) substance approved by the FDA, lactic acid has become a cornerstone ingredient across the food and beverage, cosmetics, chemical, textile, and biopolymer industries.
Understanding the chemical properties of lactic acid helps explain why it is so widely used:
Property | Value |
Chemical formula | C₃H₆O₃ |
Molecular weight | 90.08 g/mol |
Appearance | Colorless to pale yellow liquid |
Odor | Mild, slightly sour |
pH (0.1 N solution) | ~2.4 |
Boiling point | 122 °C (at 15 mmHg) |
Melting point | 16.8 °C (pure), 53 °C (racemic) |
Solubility | Fully miscible with water, ethanol, and glycerol |
Density | 1.20–1.21 g/cm³ (88% solution) |
pKa | 3.86 |
Lactic acid is a weak organic acid, significantly milder than mineral acids such as hydrochloric or sulfuric acid. This moderate acidity makes it ideal for applications where pH control is needed without aggressive chemical reactions — for example, in food preservation, personal care formulations, and industrial descaling.
In aqueous solution, lactic acid partially dissociates to release hydrogen ions and lactate anions. It also readily forms lactate salts (such as sodium lactate, calcium lactate, and potassium lactate) and lactate esters (such as ethyl lactate), which extend its functional versatility across industries.
Lactic acid is manufactured through two primary routes:
Over 90% of the world's lactic acid is produced via microbial fermentation. The process works as follows:
Feedstock
● : Renewable carbohydrates — corn starch, sugarcane molasses, cassava, sugar beet, or lignocellulosic biomass
Microorganisms
● : Selected strains of lactic acid bacteria (e.g.,Lactobacillus,Lactococcus,Bacillus) or engineered fungi/yeasts
Process
● : Under controlled temperature (30–45 °C) and pH (5.5–6.5), the microorganisms convert sugars into lactic acid through anaerobic fermentation
Purification
● : The fermentation broth is neutralized with calcium hydroxide to form calcium lactate, which is then acidified with sulfuric acid to release free lactic acid. Further purification steps — including filtration, carbon treatment, ion exchange, and evaporation — yield the final product at the desired concentration
This bio-based route is environmentally friendly, uses renewable resources, and produces biodegradable lactic acid suitable for food, cosmetic, and bioplastic applications.
Chemical synthesis routes — primarily via the hydrolysis of lactonitrile (derived from acetaldehyde and hydrogen cyanide) — produce a racemic mixture of D- and L-lactic acid. This method is less common today due to cost, environmental concerns, and the growing preference for bio-based products. However, it remains relevant for certain industrial niches.
Lactic acid is available in multiple grades, each tailored to specific application requirements:
Grade | Typical Purity | Common Concentration | Primary Applications |
Food Grade (FCC) | ≥ 88% | 80%, 88%, 90% | Food preservatives, acidulants, flavor enhancers, beverages, dairy |
Cosmetic Grade | ≥ 88% | 80%, 88% | Skincare, hair care, pH adjusters, moisturizers |
Technical / Industrial Grade | ≥ 80% | 80%, 88% | Descaling, cleaning, leather tanning, textile dyeing |
Heat-Stable Grade | ≥ 88% | 88%, 90% | PLA production, high-temperature processing |
Polymer Grade | ≥ 99% (pure L-isomer) | 90%+ | Polylactic acid (PLA) production for bioplastics |
Food grade lactic acid is produced under strict quality control and meets FCC (Food Chemicals Codex) or equivalent standards. Industrial-grade products are suitable for non-food applications where slightly different purity profiles are acceptable and cost efficiency is prioritized.
Lactic acid is one of the most widely used food additives worldwide (E270 in the EU). Its roles in food production span preservation, flavor enhancement, pH control, and mineral fortification.
Lactic acid inhibits the growth of pathogenic and spoilage microorganisms by lowering pH to levels where bacteria, yeasts, and molds cannot thrive. It is particularly effective against Listeria monocytogenes, Salmonella, and E. coli.
Common preserved foods:
● Processed meats (sausages, deli meats) — as sodium lactate or potassium lactate
● Pickled vegetables (cucumbers, olives, sauerkraut, kimchi)
● Salad dressings and sauces
● Canned vegetables and fruits
As a mild organic acid, lactic acid provides a clean, tangy taste that enhances flavor without the sharp bite of citric acid or acetic acid. It is commonly used in:
● Soft drinks and carbonated beverages
● Fruit juices and nectars
● Jams, jellies, and fruit preserves
● Confectionery and hard candies
Lactic acid is naturally produced during the fermentation of milk into yogurt, cheese, kefir, and buttermilk. Industrial cheese makers also add lactic acid to standardize pH and accelerate curd formation — especially in mozzarella, ricotta, and paneer production.
In brewing, lactic acid is used to adjust mash pH for optimal enzyme activity, enhance flavor complexity in sour beer styles (such as Gose and Berliner Weisse), and prevent microbial contamination during wort production. Winemakers also use lactic acid to correct acidity in wines grown in warm climates.
Lactic acid extends shelf life in baked goods by inhibiting mold growth and starch retrogradation (which causes staling). It also contributes to dough conditioning, improving crumb structure and volume in bread.
Lactic acid is a raw material for producing lactylate esters — such as sodium stearoyl lactylate (SSL) and calcium stearoyl lactylate (CSL) — which are widely used as dough strengtheners and emulsifiers in commercial baking.
Lactic acid has earned a prominent place in the cosmetic and personal care industry because of its multifunctional benefits.
In cosmetic formulations, pH control is critical for stability, antimicrobial preservation, and skin compatibility. Lactic acid is a preferred pH adjuster because it is gentle, naturally derived, and compatible with a wide range of cosmetic ingredients.
Lactic acid is part of the skin's natural moisturizing factor (NMF) — a mixture of compounds that helps the stratum corneum retain water. As an ingredient, it attracts and binds moisture, improving skin hydration and smoothness. Sodium lactate, its salt form, is an even stronger humectant commonly used in lotions, creams, and serums.
As an alpha hydroxy acid (AHA), lactic acid gently exfoliates the skin's surface by loosening the bonds between dead skin cells. Compared to glycolic acid, lactic acid has a larger molecular size, which means it penetrates more slowly and is generally better tolerated by sensitive skin types. It is widely used in:
● Facial exfoliating toners
● Brightening serums
● Anti-aging creams
● Body lotions for rough or uneven skin texture
At appropriate concentrations, lactic acid contributes to the preservative system of cosmetic products by creating an environment unfavorable to microbial growth — reducing reliance on synthetic preservatives.
Lactic acid is used in shampoos and conditioners to adjust pH to the mildly acidic range (4.5–5.5), which helps smooth the hair cuticle, reduce frizz, and enhance shine.
Beyond food and cosmetics, lactic acid is a workhorse in industrial chemistry. Its applications span multiple sectors:
Lactic acid effectively dissolves calcium carbonate scale (limescale) and mineral deposits. It is used in:
● Industrial boiler and heat exchanger descaling
● Dairy and brewing equipment cleaning (CIP — Clean-in-Place)
● Hard surface cleaners and bathroom descalers
● Membrane cleaning in water treatment
Compared to stronger acids like hydrochloric or phosphoric acid, lactic acid is less corrosive to stainless steel, safer to handle, and more environmentally friendly — making it the preferred choice in food-grade and sensitive equipment cleaning.
In the leather industry, lactic acid is used as a deliming agent and pH regulator during the tanning process. It helps remove lime from hides more gently than ammonium salts, producing softer, higher-quality leather with reduced environmental impact.
Lactic acid adjusts dye bath pH for acid dyes on wool, silk, and nylon, ensuring even color uptake and improved fastness. It is also used as a finishing agent to impart softness and improve fabric hand feel.
In metal finishing, lactic acid is used for mild pickling, rust removal, and as a chelating agent in electroplating baths. Its biodegradable nature makes it an attractive alternative to harsher mineral acids in environmentally regulated processes.
Ethyl lactate, the ethyl ester of lactic acid, is a biodegradable, low-toxicity solvent used in:
● Industrial paint strippers and degreasers
● Electronic cleaning and semiconductor manufacturing
● Agricultural formulations
● Printing inks and coatings
Calcium magnesium acetate (CMA) and potassium lactate — both derived from lactic acid — are used as non-corrosive, environmentally friendly alternatives to road salt for airport runway and highway de-icing.
In agriculture, lactic acid and its derivatives play multiple roles:
Silage inoculants
● — Lactic acid bacteria are added to forage crops to promote rapid fermentation, preserve nutritional value, and prevent spoilage during ensiling
Animal feed acidifier
● — Lactic acid added to feed improves gut health, enhances nutrient absorption, and reduces pathogenic bacteria in livestock and poultry
Feed hygiene
● — Lactate-based products control mold and bacterial growth in stored feed and grains
Drinking water acidification
● — Used in poultry and swine operations to lower water pH and support digestive health
No. Lactic acid (C₃H₆O₃) is the protonated acid form. Lactate (C₃H₅O₃⁻) is its conjugate base — the deprotonated anion. In most food and industrial applications, you are working with lactic acid, while lactate salts (sodium lactate, calcium lactate, potassium lactate) are used where a less acidic, buffered form is needed.
Most commercial lactic acid is vegan. It is produced by fermenting plant-based sugars (corn, sugarcane, beet) using bacteria. No animal-derived materials are involved in modern industrial production, though historically it was isolated from milk. Always confirm with your supplier if vegan certification is required for your product.
The most common commercial concentration is 88%. Lower concentrations (50%, 60%, 80%) are available, and 90%+ is used for heat-sensitive applications. In food products, lactic acid is typically used at 0.1–2.0% by weight, depending on the desired pH and flavor profile. Always refer to your specific application requirements and regulatory limits.
In many cases, yes — but they have different flavor profiles. Lactic acid provides a milder, smoother sourness; citric acid delivers a sharp, bright acidity. Lactic acid is often preferred in dairy applications, meat products, and beverages where a less aggressive acid taste is desired. The choice depends on your target flavor profile and pH requirements.
Lactic acid is a small-molecule organic acid (monomer). Polylactic acid (PLA) is a polymer — a long chain of lactic acid molecules linked together through polymerization. Think of lactic acid as individual bricks and PLA as a wall built from those bricks. PLA is a solid thermoplastic used for packaging, fibers, and 3D printing filament.
Yes. Lactic acid is designated as GRAS (Generally Recognized As Safe) by the U.S. FDA and is approved as food additive E270 in the European Union. It has been safely used in food production for over a century. Purchase food-grade (FCC) lactic acid from a reputable supplier for any food or beverage application.
Store lactic acid in a cool, dry, well-ventilated area away from direct sunlight and heat sources. Keep containers tightly sealed when not in use. Recommended storage temperature is 15–30 °C (59–86 °F). At lower temperatures, lactic acid may crystallize or become viscous — gentle warming restores it to liquid form. Use containers made of stainless steel (316L), HDPE, or polypropylene; avoid carbon steel and aluminum.
Yes, lactic acid is readily biodegradable. It is a naturally occurring substance that microorganisms in the environment can metabolize. This biodegradability is one of the key reasons it is favored in green cleaning products and environmentally sensitive applications.
When properly stored in sealed containers, lactic acid (88% solution) typically has a shelf life of 24–36 months from the date of manufacture. Heat-stable and food-grade products may have shorter shelf lives depending on packaging and storage conditions. Always check the manufacturer's COA and expiry date.
