1. Emulsion
1.1. – a dispersed two-phase system, i.e., an intimate mixture of two liquids that are immiscible under normal conditions, whereby one phase is dispersed in the other in the form of fine droplets
1.2. #Two types of simple emulsion: (a) water in oil (w/o) & (b) oil in water (o/w)
2. The stability of an emulsion depends on:
2.1. - degree of division of the inner phase - quality/stability of the interfacial film - viscosity of the outer phase - ratio & the specific weight of the volumes of the two phases
3. Emulsifiers are substances which reduce the surface tension at the interface of two normally immiscible phases, allowing them to mix and form an emulsion. Emulsifiers belong to the general class of compounds called surface-active agents or surfactants.
4. FUNCTIONS
4.1. To promote emulsion stability, stabilize aerated systems, and control agglomeration of fat globules
4.2. To modify texture, shelf life, and rheological properties by complexing with starch and protein components
4.3. To improve the texture of fat-based foods by controlling the polymorphism of fats
5. How does emulsifier work?
5.1. Emulsifiers reduce surface tension between the two immiscible phases due to their molecular structure. They have both a polar group with an affinity for water (hydrophilic), and a nonpolar group with an affinity for oil (lipohilic)
6. Types of emulsifier
6.1. Nonionic – uncharged molecules relatively insensitive to effects of pH and salt content.
6.2. Anionic – posess a negative electrical charge
6.3. Cationic – Possess a positive electrical charge; e.g., amine compounds. Not used as food additive (toxic
6.4. Amphoteric – Possess both positive and negative charges; e.g., various lecithins; may act as anionic or cationic emulsifier, depending on pH of the system
7. - HLB of 3 – 6 : a good w/o emulsifier - HLB of 7 – 9 : a good wetting agent; can be used for w/o or o/w emulsifier - HLB of 10 – 18 : a good o/w emulsifier
8. APPLICATIONS
8.1. Bread, Rolls, Buns
8.1.1. Dough conditioning/strengthening – emulsifiers that aid in development of less tacky, more extensible dough that are processed through machinery without tearing or sticking –
8.1.2. Examples of dough conditioners: calcium stearoyl lactylate, sodium stearoyl actylate (SSL), ethoxylated monoglycerides (EOM), succinylated monoglycerides (SMG), and polyoxyethylene sorbitan monostearate (PS60)
8.1.3. Crumb-softening – Emulsifiers (anionic types) that complex with starch are referred to as “crumb softeners”.
8.2. Cakes
8.2.1. Emulsifiers added to fat-containing batters function to stabilize the aerated structure and promote a finer distribution of the fat droplets.
8.2.2. Alpha-tending emulsifiers —e.g., acetic acid esters of monoglycerides, lactic acid esters of monoglycerides, and propylene glycol esters promote a finer distribution of fat droplets and an increased viscosity of the water phase
8.3. Confectionery Products & Coatings
8.3.1. used primarily to inhibit bloom, stabilize gloss, & improve palatability
8.3.2. The bloom defect can be retarded with the use of emulsifiers functioning as crystal modifiers – i.e., they stabilize the intermediate βʼ crystalline form of the fat
8.4. Frozen dairy products – Ice Cream
8.4.1. emulsifiers stabilize the foam by actually de-stabilizing the product's emulsion
8.4.2. Emulsifiers displace the protein from the fat globule surface to the aqueous phase ⇒ increase the liquid cream's viscosity and allows the fat globules to agglomerate. The increased viscosity promotes aeration, while the agglomerates stabilize the air cells once the air is incorporated.
8.5. Noodle & Pasta
8.5.1. Emulsifiers make a rigid complex with starch to protect starch granules and improve the quality of starchy foods
8.5.2. For macaroni and spaghetti, emulsifiers provide a feeling of elasticity, and a smooth uniform surface which inhibits sticking after boiling