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Week 7: EMULSIFIERS - Coggle Diagram

- - - - Principles :check:
        
        What is emulsifier: amphiphilic contains both lipophilic and hydrophilic regions
        
        hydrophilic part may be:
        
        Non-ionic e.g. glycerol
        
        Anionic e.g. lactate, tartaric
        
        Cationic (eg lauric arginate)
        
        Amphoteric e.g. phosphatidylcholine
        
        hydrophobic (lipophilic) part of the emulsifier may consist of a fatty acid
        
        Emulsifying action
        
        based on the emulsifier ability to reduce the surface tension at the interfacial surface between the 2 phases.
        
        emulsifier form a monomolecular layer that effectively holds the interfaces, therefore oil droplets do not coalesce.
        
        Stabilisation of emulsion
        
        surface of the dispersed phase carries the same charges
        
        Electrical repulsion tends to keep the droplets from making contact
      - enable such systems to attain an acceptable shelf-life.
      - increase the stability of food systems
    - - When oil and water solution stands, 2 layers formed.
        
        When energy (agitation) applied, emulsion formed.
        
        Higher surface tension liquid will form many small droplets (dispersed phase) surrounded by continuous phase.
        
        Formation of small droplets has far larger surface area than as 2 layers.
        
        Droplets tend to coalesce when bump into each other in the emulsion.
        
        Larger droplets form, until 2 layers formed again.
        
        1 more item...
- - - - Phospholipids consist of:
        
        a hydrophilic (water loving) head and
        
        a hydrophobic (water fearing) tail
    - - Examples:
        
        Polysorbate 60: polyoxyethylene sorbitan monostearate or TWEEN 60
        
        Polysorbate 65: polyoxyethylene sorbitan tristearate
        
        Polysorbate 80: polyoxyethylene sorbitan monooleate
      - The number “XX” following the 'polysorbate' refers to the total number of oxyethylene groups in the molecule
    - - Control grainy texture in margarines.
      - Control fat bloom in chocolate
    - - form strong complex with gluten in starch in baked products → Hence, able to hold gas bubbles better.
  - - - Dough: Anionic emulsifier (Sodium Stearoyl -2-Lactate, SSL) allows gluten proteins to bind together, thus produces an elastic dough.
        
        Also known as dough conditioners/ strengtheners
        
        Able to hold gas to yield
        
        greater loaf volume and softer crumb.
        
        Faster proof times due to increased volume
        
        Improve mixing tolerance
        
        Improve shock tolerance
      - Bread :check:
        
        Anti-Staling: Emulsifiers eg. DATEM (Diacetyl Tartaric Ester of Monoglyceride) are used to ensure that bread stays softer and fresher for a longer time.
        
        (prevents) Staling
        
        (from) Gelatinisation: During baking, starch granules absorb moisture from its surroundings and gelatinise due to high heat. A portion of amylose and amylopectin are released into the surrounding matrix.
        
        (and) starch retrogradation: During cooling, both amylose and amylopectin form new linkages with each other to form a crystalline structure releasing moisture.
        
        emulsifier with its linear tail allows amylose or amylopectin to form helix complex with it.
        This slows down retrogradation process as the bound amylose is unable to form new bonds and revert to its crystalline state.
      - Cakes :check:
        
        Alpha tending emulsifier: When hydrated convert to the alpha crystalline form, which helps to:
        
        Increase cake volume as it facilitates air incorporation
        
        Improve moisture retention, texture & grain size.
        
        Disperse shortening in smaller particles to allow maximum number of air cells.
        
        Example
        
        Calcium/sodium stearoyl-2-lactate (CSL/SSL)
        
        DATEM
        
        Monoglycerides
        
        Polysorbates
    - - Emulsifiers
        
        Additional
        
        mono- and di-glycerides
        
        sucrose esters
        
        polysorbates
        
        polyglycerol esters (PGE)
        
        Natural: Lecithin
        
        Purposes
        
        Increase resistance to shrinkage – strengthening foam
        
        Good heat shock tolerance
        – less/no shrinkage
        
        Provides smoother texture with formation of smaller ice crystals and air cells
        
        smooth (small) air bubbles that are evenly distributed.
        
        Increases melting time
        
        Enhances Melting Tolerance
        
        Improve fat dispersion.
        
        Facilitate fat-protein interactions
        
        Control fat agglomeration
        
        Facilitate air incorporation for softer ice-cream, increasing profits
        
        (With higher) Overrun (volume) = (After Freeze – Before Freeze/Before Freeze) x 100%
        
        volume of finished product eg. ice cream or whipped cream > Volume of mix before whipping by 50%
        
        Reduce whipping time and improve whippability
    - - Examples: Mono- & di-glycerides, polysorbate, sorbitan esters, propylene glycol monostearate polyglycerol esters.
      - Margarines
        or spread
        
        Spreadability (fat crystal modification)
        
        Anti spattering when frying
        
        stabilize β’ prime fat crystals to prevent grainy and sandy texture
      - Commercial shortenings
        
        Good prevention of syneresis
        
        Good creaming properties for baking
    - - Improves Shelf life & Enhances palatability
      - Changes crystal structures: Prevents bloom in chocolate & candy
      - Stabilizes fat structures: Control viscosity
      - Syneresis reduced in high sugar pastes &Reduce ‘stickiness’
      - especially Chocolate
        
        Reduces Blooming: migration of fat crystals in chocolate to surface.
        
        Cause: storage temperature is unstable.
        
        Effect: the fat crystals changes from β’ to β crystal and recrystallizes
        
        Result: chocolates look dull with greyish patches or spots.
        
        By slowing down the crystallisation rate of cocoa butter with sorbitan tristearate/ Sorbitan monostearate
        
        (have 2 properties)
        
        Highly fat soluble emulsifier
        
        Able to co-crystallize with triglycerides in chocolate to stabilize β’ crystals.
    - - In oil/water emulsions
        as mono- & di-glycerides, polysorbates and sorbitan esters.
      - Used as wetting agents in e.g. Milo, coffee creamer: Reduce interfacial tension between liquid & solid surfaces
        
        easy to spread evenly over the surfaces.
    - - Polymorphism – the ability of fat crystals exist in many forms.
        
         (alpha) crystals
        
        smallest and most unstable
        
        formed when chilled rapidly with agitation
        
        β’ (beta-prime) crystals
        
        small, needle like, about 1μ
        
        forms very smooth surface
        
        formed when fat is agitated during cooling
        
        melt gradually in warm condition
        
        highly desirable in margarines and spread
        
        β (beta) crystals
        
        extremely stable
        
        largest fat crystal, about 25 to 100μm
        
        formed when fat is melted completely
        
        chilled slowly, without being disturbed
        
        highly undesirable in food, grainy fat texture
- - - - Oil-in-water emulsion: Oil is the dispersed liquid and
        Water or aqueous solution is the continuous phase
        
        eg. Mayonnaise
      - Water-in-oil emulsion: Water or aqueous solution is the dispersed phase
        Oil is the continuous phase
        
        eg. Butter.
    - - Oil in Water
        
        Uniform content.
        
        water diluted the continuous phase (water)
      - Water in Oil
        
        2 layers formed:
        
        water bottom,
        
        product (emulsion) floats.
  - - - Formulae
        
        HLB value* = 20 x [Mr of Hydrophilic (loves water)/ Mr of Lipophilic (loves oil)]
        
        HLB value= 20 x [1 - S/A ]
        
        Where S: Saponification no of ester/fat - KOH in mg needed to saponify 1g of fat
        
        Saponify:turn (fat or oil) into soap by reaction with an alkali OR convert (any ester) into an alcohol and a metal salt by alkaline hydrolysis.
        
        Where A: Amount of fatty acids in chemical compound
      - The value of HLB ranges from 0 - 20.
        
        Low HLB emulsifiers are soluble in oil (w/o).
        
        High HLB emulsifiers are soluble in water (o/w).
    - - Category
        
        Anti-staling in bread
        
        Alpha – tending in cakes
        
        Foam stabilizer in ice cream
        
        Lipid crystal modifying in chocolate
        
        Wetting agent
        
        (prevent lumps form when added to liquid)
      - Applications
        
        Bakery products
        
        Cake Mixes
        
        Cookies and crackers
        
        Sweet goods and icings
        
        Margarine, dressings, shortenings
        
        Confectionaries
        
        Deserts and toppings
        
        Dairy products
    - - Sucrose esters / Lactic acid esters
      - Natural emulsifiers
        Lecithin & Phosphatides
      - Sorbitan esters & Polysorbates
      - Fatty acid esters: Depending on the properties of fatty acid tails (eg length)
        
        Glycerol fatty acids esters
        
        Hydroxycarboxylic acid & fatty acid esters
        
        Polyglycerol fatty acid esters
        
        Ethylene or Propylene glycerol fatty acid esters
    - - Anionic: (-)ve charge on polar portion in alkaline solutions
      - Cationic: (+)ve charge on polar portion in low/ neutral solutions
      - Non-ionic: no charge. Used along or together with charged emulsifiers
      - Amphoteric: (-)ve & (+)ve charges on polar portion