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Introduction
E475, also called polyglycerol esters (PGE), are non-ionic emulsifiers produced by esterifying polyglycerol (a mixture of glycerol polymers with 2-10 glycerol units) with edible fatty acids. The polyglycerol backbone can be linear or branched, with chain lengths ranging from diglycerol (2 units) to decaglycerol (10 units). The number of glycerol units and the degree of esterification (how many fatty acids are attached) determine the HLB value, which ranges from approximately 5-14. Most commercial E475 products are based on triglycerol (3 units) or tetraglycerol (4 units) with 1-3 fatty acid residues.
E475 is known for its excellent aeration properties and its ability to form stable oil-in-water emulsions with very small droplet sizes. Unlike mono- and diglycerides (E471) which tend to form lamellar phases, polyglycerol esters form more fluid interfacial films that allow for rapid incorporation of air bubbles. This makes E475 particularly valuable in cakes, whipped toppings, and frozen desserts. It is approved in EU, USA (as polyglycerol esters of fatty acids, 21 CFR 172.854), Japan, and Codex.
CAS Number
Mixture. Polyglycerol (average 4 units) esters: 68412-64-6 (polyglycerol oleate), 67784-82-1 (polyglycerol stearate).
Synonyms
Polyglycerol esters of fatty acids, PGE, Polyglycerol fatty acid esters, Triglycerol monostearate (specific type), E475.
Topic Headings
1. Mechanisms of aeration and foam stabilization (detailed paragraph form)
In products like cakes and whipped toppings, air bubbles must be incorporated and stabilized against coalescence. During mixing, air bubbles are sheared into smaller bubbles (10-50 microns diameter) but these are thermodynamically unstable and will rapidly merge unless an emulsifier adsorbs to the air-water interface. E475 is exceptionally effective for three reasons. First, the polyglycerol head group is large and flexible, allowing it to cover more surface area per molecule than mono- and diglycerides. Second, the multiple hydroxyl groups on polyglycerol form hydrogen bonds with water molecules, creating a hydrated layer around each air bubble that physically prevents bubble-bubble contact. Third, unlike protein-based foaming agents (egg white, casein) which denature at high temperatures, E475 remains stable during baking. In a typical cake batter, E475 at 0.4-0.6% (flour basis) increases batter specific gravity from 0.8 to 1.1 (more air incorporated) and produces 35-50% greater baked volume. The resulting crumb has finer, more uniform cells and remains soft longer because smaller air cells provide more even stress distribution.
2. Comparison of different polyglycerol chain lengths (list form)
• Diglycerol esters (2 units) — Lower HLB (5-7); better for water-in-oil emulsions (margarine); less effective for aeration.
• Triglycerol esters (3 units) — HLB 7-10; standard for cakes and whipped toppings; best balance of aeration and emulsion stability.
• Tetraglycerol esters (4 units) — HLB 9-12; superior for low-fat (<20% fat) whipped products; produces very small air bubbles (20-30 microns).
• Hexaglycerol esters (6 units) — HLB 12-14; very hydrophilic; used in beverage emulsions; less effective for aeration because they are too water-soluble.
• Decaglycerol esters (10 units) — HLB 14-16; water-soluble; used as solubilizers for flavors and oils in clear beverages; minimal aeration capability.
3. Applications in various food categories (list form)
• Cakes (pound, layer, sponge) — 0.4-0.8% gives 40-50% volume increase; produces "velvet crumb" with extremely fine, uniform cells; reduces egg requirement by 20-30%.
• Whipped toppings (dairy and non-dairy) — 0.3-0.7% gives 250-350% overrun; stable foam for 24+ hours refrigerated; does not weep (water separation).
• Ice cream — 0.2-0.4% improves overrun to 90-110%; reduces ice crystal size (30-40 microns vs 60-80 microns without); gives smoother texture.
• Coffee whiteners (liquid) — 0.3-0.5% prevents feathering and oil separation; improves whitening power.
• Margarine and low-fat spreads — 0.2-0.4% (low HLB grade) stabilizes water droplets; reduces spattering and improves spreadability.
• Chocolate and compound coatings — 0.2-0.3% reduces viscosity (allows less cocoa butter); improves gloss and bloom resistance.
• Cream liqueurs — 0.4-0.6% prevents cream separation in alcohol-containing products (15-20% ethanol); stable for 24+ months.
4. Regulatory, safety, and stability (paragraph form)
JECFA established an ADI of 0-25 mg/kg body weight for polyglycerol esters (slight laxative effect at very high doses). However, typical intake is far below this (estimated 1-3 mg/kg/day in Europe and North America). Metabolism studies show that E475 is hydrolyzed by pancreatic lipase into polyglycerol and free fatty acids. Polyglycerol is poorly absorbed (80-90% excreted in feces) and the remainder is excreted in urine unchanged. No toxicity, genotoxicity, or reproductive effects have been observed. EU maximum levels: 10 g/kg in cakes and fine bakery wares, 5 g/kg in ice cream, 5 g/kg in toppings. USA: GRAS under 21 CFR 172.854 with no specific limits when used as emulsifier or stabilizer. Storage: stable for 18 months in sealed containers below 30°C. E475 is heat-stable up to 200°C but should not be heated above 180°C for extended periods (darkening and slight odor development). It is resistant to hydrolysis at pH 4-9 but degrades at pH <3 or >10.
