| HS Code | 216631 |
| Chemical Name | Propylene Glycol Alginate |
| Synonyms | PGA; Hydroxypropyl alginate; Propylene glycol ester of alginic acid |
| Cas Number | 9005-37-2 |
| E Number | E405 |
| Chemical Formula | (C9H14O7)n approximate; actual varies with esterification |
| Molecular Weight | Polymeric; typical range 10,000-200,000 g/mol depending on grade |
| Appearance | White to pale yellowish-brown powder, granules, or fibrous solid |
| Odor | Slight characteristic odor; essentially odorless when dry |
| Solubility | Soluble in water forming a viscous colloidal solution; insoluble in ethanol, ether, and most organic solvents |
| Viscosity | Varies by grade; 1% aqueous solution at 20-25°C commonly about 20-1000 mPa·s |
| Ph | 1% aqueous solution typically pH 3.0-5.0 |
| Degree Of Esterification | Typically 40-85%, depending on product specification |
| Moisture Content | Usually ≤ 15% by weight, product-dependent |
| Ash Content | Usually ≤ 10% by weight, product-dependent |
As an accredited Propylene Glycol Alginate factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Propylene Glycol Alginate is packaged in 25 kg net polyethylene-lined fiber drums, sealed to protect against moisture. |
| Container Loading (20′ FCL) | 20′ FCL: Propylene Glycol Alginate packed in 25 kg drums on pallets, secured, dry, clean, well-ventilated container. |
| Shipping | Propylene Glycol Alginate is a non-hazardous, food-grade powder. Ship in sealed polyethylene-lined bags or fiber drums inside clean, dry containers. Protect from moisture, direct heat, and contamination. No dangerous goods declaration is required under IATA/IMDG/ADR when shipped dry and uncontaminated. Standard freight handling applies. |
| Storage | Store Propylene Glycol Alginate in a cool, dry, well-ventilated area away from heat, sparks, and direct sunlight. Keep containers tightly sealed to protect against moisture absorption. Avoid dust generation and contact with strong oxidizers. Ensure proper labeling and handling with appropriate PPE to prevent eye, skin, or respiratory irritation. |
| Shelf Life | Propylene glycol alginate has a shelf life of 24 months if kept cool, dry, and sealed in original packaging. |
PGA is prehydrated separately in demineralised water at 60–70 °C for 15–20 min before being dosed into a cooled, fermented milk base. Direct dry addition to finished acidified milk at pH < 3.8 is avoided on production lines because the powder forms partially swollen fisheyes and the ester linkage begins to hydrolyse at elevated temperature. A dry premix with sucrose or glucose syrup at 1:5 w/w is standard practice for high-shear mixing vessels. Final dosage in drinking yoghurts and lactic acid fruit drinks ranges from 0.10 wt% to 0.50 wt% of finished beverage mass. The hydrated solution is cooled below 35 °C before blending with the acidified base to limit serum viscosity loss and protect flavour volatiles.
The stabilisation mechanism is not simple thickening. Propylene glycol ester substitution reduces calcium reactivity relative to sodium alginate, which is decisive when the beverage contains milk minerals, added calcium, or fruit concentrates. In systems with total Ca²⁺ above 1200 mg/L, elastic microgel formation can still develop with PGA, particularly when the product is held above 35 °C for more than 48 h. Process lines therefore combine a two-stage homogenisation pass at 150–200 bar with a downstream plate cooler. Homogenisation reduces casein-PGA complex size and keeps the particle size distribution below 5 μm D90 when measured by laser diffraction according to ISO 13320:2020. On dairy lines, APV Gaulin or equivalent homogenisers are operated after mixing, and the shear regime is set by the first-stage pressure rather than by the circulation pump. A 1% aqueous solution of food-grade PGA typically shows Brookfield RVT viscosity of 100–400 mPa·s at 25 °C and 20 rpm, but this range narrows significantly across production batches if the esterification degree falls outside the supplier specification. End products include ambient-shelf-stable lactic acid beverages, flavoured drinking yoghurt, and fermented fruit-milk blends in single-serve PET bottles.
| Market | Regulatory reference | Function statement | Specification anchor |
|---|---|---|---|
| EU / EEA | Regulation (EC) No 1333/2008 | Food additive E405; permitted in listed food categories under quantum satis where listed | Commission Regulation (EU) No 231/2012 |
| United States | FDA 21 CFR 172.858 | Emulsifier, stabiliser, thickener at current good manufacturing practice | Food Chemicals Codex |
| FAO/WHO | JECFA monograph | Identity and purity specification for propylene glycol alginate | Esterified carboxyl content and propylene glycol limits |
PGA is introduced into bright beer lines after filtration and before filling, normally at 20–50 mg/L. Dosing at this point avoids additive loss on the filter cake and prevents downstream oxygen pick-up. The stock solution is prepared as a 0.5–1.0 wt% aqueous dispersion with deaerated water at 20–25 °C, then injected through a variable-speed diaphragm pump fitted with a pulsation damper. Static mixers of 6–8 elements are installed downstream of the injection point to guarantee dispersion without creating foam surge. On a 12,000 bottle/h filling line, the buffer vessel level control must be decoupled from the dosing pump because pressure pulses cause erratic addition and inconsistent head retention between batches.
The functional action occurs at the gas–liquid interface. Propylene glycol groups give the alginate backbone partial hydrophobic character, allowing it to reinforce the stabilising film around CO₂ bubbles without precipitating with beer proteins. The dose response is not linear: incremental improvement in NIBEM 30 values appears between 20 mg/L and 50 mg/L, whereas doses above 60 mg/L may generate chill haze at 0 °C in low-protein lager. Foam testing should follow EBC method 9.42 or an equivalent NIBEM procedure, because visual foam height alone masks bubble size distribution changes. Published data for specific lager formulations is limited. Bottle-to-bottle variations often dominate when the stock solution is older than 24 h. Approved use of PGA in beer is not globally harmonised, so export specifications must be verified against the target market before label development. Terminal products include filtered lager and low-alcohol beer variants that would otherwise show rapid head decay after pouring.
For spoonable dressings and low-oil vinaigrettes, PGA functions as an acid-stable thickener rather than as a primary emulsifier. Final use concentrations range from 0.20 wt% to 0.80 wt% in the aqueous phase. The dry powder is first dispersed in water with salt and sugar at 60–70 °C, then cooled to 20–25 °C before oil addition. Oil droplets are formed under a rotor-stator mixer running at 3000–5000 rpm, followed by a single-pass homogenisation at 150–250 bar. This sequence lowers droplet size below 5 μm D90 and stabilises the continuous phase without the need for egg yolk in reduced-fat formulations.
PGA is not a high-HLB surfactant. It does not replace lecithin or monoglycerides when a fine emulsion is required. Its contribution is continuous-phase viscosity and formation of a charged hydrated film around droplets at pH 3.2–3.8. In high-acid dressings, unmodified sodium alginate gels or loses viscosity at low pH, while PGA retains functional viscosity because the esterified carboxyl groups remain protonated but non-gelling. Process limits are specific: aqueous phase pH below 2.8 and hot holding above 70 °C should be avoided because ester hydrolysis accelerates and emulsion stability drops sharply. Particle size distribution should be checked by laser diffraction according to ISO 13320:2020 after homogenisation. End products include low-fat mayonnaise analogues, single-serve vinaigrettes, and cold-filled salad dressings packed in glass or multilayer bottles.
In fruit glazes and neutral bakery gels, PGA is used at 0.20–0.50 wt% to control water release in finished pastry. The hydrocolloid is preblended with sugar at 1:5 before dispersion in water at 80–85 °C. Heating continues for 3–5 min to fully hydrate the polymer. The batch is then cooled to 60 °C before depositing onto baked surfaces or into fruit toppings. Acid-tolerant behaviour is critical because fruit glazes commonly reach pH 3.5–4.0, where other alginate salts may lose thickening or form weak acid gels.
Dosage above 0.50 wt% in neutral glaze can raise low-shear viscosity beyond 5000 mPa·s, causing strings during spray application and surface cracking after drying. The formulation window is narrow. Production operators monitor cooled-batch viscosity with a Brookfield RVT at 20 rpm and adjust buffer juice solids rather than increasing PGA content. The finished glaze remains slice-stable during 28-day ambient storage with no visible syneresis when the bake-cool line reaches 35 °C before packaging. End products include fruit flan coatings, glazed Danish pastry, and neutral spray gels used in frozen bakery lines.
Pulp sedimentation in low-calorie juice drinks is controlled by creating a weak yield stress with PGA at 0.10–0.30 wt%. The gum is dispersed in 50–60 °C water with sugar or erythritol at 1:5 before blending with the concentrate. The mixture is homogenised at 80–120 bar to disperse cloud particles and stabilise pulp suspension. At pH 3.0–3.6, PGA retains viscosity and does not form calcium gels with pulp minerals. Prolonged recirculation above 85 °C can reduce molecular weight and lower yield stress, causing pulp settlement in the bottle neck. Production lines therefore cool to 20–25 °C before filling or use return-flow coolers. End products include orange nectar, low-sugar fruit drinks, and aseptic juice blends with visible pulp.
Acid-dye textile print paste on silk, wool, and polyamide requires a thickener that can maintain screen release at pH 4.0–5.5 without resinifying in the fixation steamer. Propylene glycol alginate is prepared as a 2–4 wt% stock paste in cold deionised water at 10–15 °C and allowed to swell for 30–60 min under slow agitation. Ammonium sulfate is added at 1–2 wt% as an acid donor, followed by the acid dye or metal-complex dye. The paste is applied by rotary-screen printing at 40–80 m/min or flatbed printing at lower speed. Fixation follows at 102 °C for 20–40 min on silk and wool, or for shorter steam cycles on polyamide depending on fabric weight.
The acid-stable thickening action keeps outlines sharp because the paste does not collapse when the acid donor lowers the pH during steaming. Sodium alginate, by comparison, can show viscosity loss and bleed in strong acid dye systems. Printed fabric is tested for wash fastness according to ISO 105-C06 after a standard reduction-clear or hot rinse. Mill practice records that screen blocking occurs when the stock paste is mixed at water temperatures above 25 °C, because partially hydrated particles swell unevenly and leave gel residues on the mesh. Published data for this specific configuration is limited; dosing must be confirmed on a print trial before bulk production. End outputs include printed silk scarves, polyamide performance apparel panels, and wool home-textile fabrics.
Grease-resistant paper coating is a smaller industrial outlet where PGA is evaluated as a film-forming auxiliary in starch-based size press formulations. A bath containing 0.5–1.5 wt% PGA and 4–6 wt% oxidised starch is applied on a puddle size press at 80–120 m/min. The first two drying cylinders operate at 90–110 °C to avoid film blistering. On 40 g/m² machine-glazed base paper, two consecutive size press passes typically raise the KIT oil holdout value to 5–6 when measured according to TAPPI T 559 cm-12. This is not a PFAS-level barrier. The film reduces oil penetration by closing surface voids and forming an oil-resistant continuous layer under converting heat.
The key formulation incompatibility is cationic polymer retention aid chemistry. PGA is anionic and can form precipitates with cationic starch or polyamine retention agents, causing deposits on the press roll and holes in the sheet. The wet-end charge balance must be checked before introducing PGA into the size press loop, because broke recirculation carries anionic polymer back to the wet end. Operational limits include a bath temperature ceiling of 60 °C to avoid molecular weight loss and a pH target of 6.5–7.5 for optimum film formation. Published data for PGA-specific mill-speed configurations is limited; most paper trials are based on alginate chemistry rather than fully esterified PGA. End products include grease-resistant sandwich wrap, bakery tissue, and compostable food service paper.
Competitive Propylene Glycol Alginate prices that fit your budget—flexible terms and customized quotes for every order.
For samples, pricing, or more information, please contact us at +8615651039172 or mail to sales9@bouling-chem.com.
We will respond to you as soon as possible.
Tel: +8615651039172
Email: sales9@bouling-chem.com
Flexible payment, competitive price, premium service - Inquire now!
Propylene glycol alginate is the propylene glycol ester of alginic acid obtained from brown macroalgae, principally Laminaria hyperborea, Macrocystis pyrifera, and Lessonia nigrescens. The manufacturing sequence includes hot alkaline extraction of alginate from the cell wall matrix, precipitation or filtration, conversion to sodium alginate, acidification to alginic acid, and reaction with propylene oxide under controlled pressure. The esterification reaction replaces a portion of the carboxylate groups on β-D-mannuronic acid and α-L-guluronic acid residues with hydroxypropyl ester groups. The resulting product is identified by CAS 9005-37-2, INS 405, and E number E405 under European Union food additive legislation. The material is supplied as a cream to light tan powder with a mild odor and a bulk density typically between 0.35 g/cm³ and 0.75 g/cm³. Particle size specifications usually control retention on a 60-mesh or 80-mesh sieve, with 95% passing through 0.180 mm openings for high-dispersion grades.
The partial esterification reduces anionic charge density relative to sodium alginate and introduces hydrophobic propylene glycol groups along the polysaccharide chain. This structural modification produces three functional consequences: solubility in cold water without alkaline pH adjustment, reduced precipitation in the presence of calcium ions, and interfacial activity at oil-water and air-water boundaries. In contrast to sodium alginate, which is highly calcium-sensitive and acid-sensitive, propylene glycol alginate does not form rigid egg-box junction zones under typical food processing concentrations. Instead, it functions as an acid-stable thickener, emulsion stabilizer, and foam stabilizer in processed foods and beverages. Commercial grades are not described by model codes in the same way as synthetic polymers; they are differentiated by apparent viscosity, degree of esterification, residual propylene glycol, and particle size. The product is supplied under short designations such as low-viscosity, medium-viscosity, and high-viscosity types, with viscosity measured at 1% concentration in deionized water at 25 °C.
Batch-to-batch variation in the mannuronic acid to guluronic acid ratio, typically between 1.0 and 2.5 depending on brown algal species, influences chain stiffness and calcium sensitivity even after esterification. Laminaria hyperborea types have high guluronate block content and are normally used for calcium gel formation in sodium alginate grades; for propylene glycol alginate, Macrocystis pyrifera and Lessonia nigrescens often provide lower gel potential and better acid-emulsion performance. Manufacturers control the molecular weight of the source alginate and the propylene oxide reaction parameters to produce stable low-, medium-, and high-viscosity grades. The product is therefore not a single ester but a family of partially esterified alginates with varying degrees of substitution. This is why certificates of analysis report degree of esterification and viscosity rather than a fixed molecular weight or degree of polymerization.
Specification control is necessary because viscosity and esterification directly affect emulsifying capacity and calcium tolerance. Apparent viscosity is measured on a 1% solution at 25 °C using a Brookfield LV viscometer at 12 rpm. Commercial low-viscosity grades generally fall between 100 mPa·s and 300 mPa·s; medium-viscosity grades between 300 mPa·s and 600 mPa·s; high-viscosity grades can reach 1100 mPa·s under the same conditions. Degree of esterification is typically controlled between 40% and 80%, with higher values selected for low-pH, calcium-fortified, or hard-water formulations. The JECFA and Food Chemicals Codex monographs specify limits for free propylene glycol, total propylene glycol, and drying loss. Within the European Union, propylene glycol alginate is permitted as E405 under Regulation (EC) No 1333/2008 Annex II, and in the United States under FDA 21 CFR 172.858. Table 1 lists the common release parameters used in bulk ingredient certificates of analysis. Limits for lead and arsenic are applied per FCC 14 monograph, while microbial limits are determined by ISO methods.
| Parameter | Unit | Typical range or limit | Test or standard |
|---|---|---|---|
| Apparent viscosity, 1% solution, 25 °C | mPa·s | 100–600 grade-dependent | Brookfield LV, 12 rpm |
| Degree of esterification | % | 40–80 | Titrimetric or instrumental, FCC 14 |
| Free propylene glycol | % | ≤15 | FCC 14 |
| Total propylene glycol | % | 15–45 | FCC 14 |
| Loss on drying | % | ≤20 | FCC 14 |
| Particle size through 80-mesh sieve | % | ≥95 | Sieve analysis, ISO 3310-1 |
| Arsenic | mg/kg | ≤3 | FCC 14 |
| Lead | mg/kg | ≤5 | FCC 14 |
| Total plate count | CFU/g | ≤5000 | ISO 4833-1:2013 |
| Yeast and mold | CFU/g | ≤500 | ISO 21527-2:2008 |
| Salmonella | per 25 g | Absent | ISO 6579-1:2017 |
Because the viscosity test is concentration-dependent, users should verify that specification comparisons are made at the same shear rate and temperature. Differences between 1% and 2% solutions can be nonlinear in high-molecular-weight grades, and hydration time must be standardized to avoid underdeveloped viscosity readings. The residual propylene glycol content is not an inert marker; it affects cold-water dispersibility and can influence the tendency of the powder to cake under humid storage conditions.
Low-pH emulsified sauces and spoonable dressings are the main application class where propylene glycol alginate is specified. The polymer is pre-dispersed in oil or dry-blended with sugar to avoid the formation of partially hydrated lumps, then hydrated under high-shear mixing. A typical addition rate in the aqueous phase is 0.1% to 0.5% by total formula mass, depending on oil content, pH, and target yield stress. In a two-stage homogenizer, pressures of 150 bar first stage and 30 bar second stage are used to reduce oil droplet size after the polymer has fully hydrated. The esterified polysaccharide adsorbs at the oil-water interface and contributes steric hindrance around dispersed oil droplets, reducing coalescence during storage at 4 °C to 25 °C. In tomato-based sauces and acidic condiments with pH values between 3.2 and 4.0, the carboxylate groups remain sufficiently ionized to provide thick but non-stringy rheology, while the ester groups maintain solubility where sodium alginate begins to lose viscosity and precipitate as alginic acid.
Suspension of fruit pulp or insoluble cloud particles in low-pH beverages uses the same acid-tolerant thickening mechanism. In citrus drinks with pH 2.8 to 3.5, a dosage of 0.05% to 0.2% reduces sedimentation during shelf storage. The polymer is first dispersed in 10% sugar syrup or a non-aqueous carrier such as propylene glycol, then added to a high-shear mixer. A rotor-stator mixer operating at 3000 rpm for 5 min is sufficient to complete hydration at 20 °C to 25 °C. This procedure avoids the high-temperature hydration step often required for guar gum or locust bean gum, which display poor acid stability and can develop off-flavors from thermal processing. Because propylene glycol alginate is non-gelling under normal processing calcium levels, it can be used in hard water without the pre-sequestration step required for sodium alginate. Published data for the specific heat stability of high-viscosity grades in retorted acid emulsions is limited; application trials should verify viscosity retention at process temperatures above 100 °C because ester hydrolysis can occur in moist heat, particularly at pH values above 8.0.
The functional distinction between propylene glycol alginate and sodium alginate arises from the partial blocking of carboxyl groups. Sodium alginate forms gel networks in the presence of calcium ions through the egg-box mechanism between contiguous guluronate blocks; propylene glycol alginate has a reduced average guluronate block length available for calcium crosslinking and therefore remains dispersible in calcium-containing emulsions. Xanthan gum also remains soluble in acidic and calcium-bearing systems, but it lacks the same interfacial activity because its primary structure is based on a cellulose backbone with trisaccharide side chains and weak surface activity. Table 2 compares the three hydrocolloids under conditions relevant to acidified beverage and emulsion processing. Comparative quantitative data on the minimum calcium concentration required for visible gelation of different alginate esters is limited by source-dependent monomer ratios and degree of esterification. In practice, sodium alginate is selected when calcium gelation is the intended textural outcome, while propylene glycol alginate is selected when acid stability, foam stabilization, or interfacial emulsification must be maintained without the risk of localized gelation.
| Property or function | Propylene glycol alginate | Sodium alginate | Xanthan gum |
|---|---|---|---|
| Calcium sensitivity at pH 4.0–5.0 | Low; no rigid gel at typical use | High; gelation at low calcium concentration | Low; no gelation |
| Acid tolerance at pH 3.0–4.0 | Stable; retains thickening and emulsifying | Loss of viscosity; precipitation as alginic acid | Stable; may require higher shear for hydration |
| Emulsifying activity in oil-in-water systems | High due to propylene glycol ester hydrophobe | Very low | Low to moderate |
| Beer foam stabilization | Strong at low addition rates | Poor; calcium sensitivity and acid instability | Moderate in some formulations |
| Typical use level in acidified dressings | 0.1–0.5% | 0.5–1.5% | 0.05–0.5% |
| Primary application | Low-pH emulsified sauces, dressings, beer foam | Gelling agents, spherification, thickening | Suspension, mouthfeel, gluten-free bakery |
The presence of calcium ions in hard water or fortified systems is therefore a key selection criterion. Sodium alginate may require calcium-sequestering agents or dilution of the aqueous phase before hydration, while propylene glycol alginate can be incorporated directly into the same aqueous stream. However, propylene glycol alginate is not a direct replacement for xanthan gum where suspending yield stress without interfacial activity is the primary requirement, because the former is more surface-active and can generate foam in high-shear mixing if air entrainment is not controlled.
Propylene glycol alginate is used in brewery operations at low addition rates to increase foam adhesion, lacing, and head retention. The material is usually prepared as a 0.5% to 1.0% stock solution in deaerated water at 10 °C to 20 °C, then dosed in-line after final filtration and before packaging. Dosing rates in finished beer are typically between 20 mg/L and 80 mg/L. The polymer adsorbs at the air-liquid interface and interacts with foam-positive polypeptides derived from malt, stabilizing the bubble film against drainage and coalescence. Because beer pH is usually between 4.2 and 4.5, sodium alginate would be at risk of acid precipitation or calcium-induced haze in the presence of brewing liquor calcium ions, whereas propylene glycol alginate retains solubility and does not generate visible calcium gel particles.
Overdosing above approximately 100 mg/L can produce persistent suspension haze and overstable foam that complicates filling, so in-line mass flow meters or diaphragm metering pumps are used for precision addition. The product should be protected from oxygen, and stock solutions should be used within 24 h if not preserved, because oxidative depolymerization and microbial growth can cause viscosity loss and off-flavors. Addition before flash pasteurization can expose the polymer to elevated temperature and shear; for flash pasteurized beer, the stock solution is preferably added after cooling to 2 °C to 4 °C to minimize ester hydrolysis and thermal depolymerization. Because propylene glycol alginate solutions are shear-thinning, in-line viscometers are used to verify concentration before the dosing point. In this application, propylene glycol alginate differs from gum arabic and carrageenan because gum arabic has limited foam crosslinking activity and carrageenan is more calcium-sensitive and can contribute to haze in pasteurized beer.