Colloid and surface phenomena aspects of Chocolate

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Colloid and surface phenomena aspects of Chocolate

• Chin Kok Ooi
• Teck Yu Sia
• Anshu Verma
• Shushan Munshi

CE 457/527
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Introduction

• Chocolates has a wide variety and found in common
  places
• Has to meet consumer need
• Types of chocolates
• Good for health

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Marketing

• Designing chocolates
• Energy
• Size
• Price
• Efficiency
• Legal requirements
• Advertisement

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Components and Compositions

• The ingredients of chocolate
• Cocoa, cocoa butter, milk and sugar
• Additional ingredients
• Lecithin(emulsifier) and flavoring agents

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Cocoa and Cocoa butter

• Both are obtained from the seeds of Theobroma
  Cocoa.
• Cocoa beans grow in pods.

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Cocoa and Cocoa butter

• General compositions of cocoa bean

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Cocoa and Cocoa butter

• Alkaloids
• Theobromine and caffeine
• Theobromine 3,7-dimethyl-xanthine
• Caffeine 1,3,7-trimethyl-xanthine
• Cocoa red is formed during the drying of the
  beans by the action of enzymes on the glucosides.

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Cocoa and Cocoa butter

• Special characteristics of cocoa butter
• The melting point of cocoa butter is between 32C
  and 36C.
• In spite of low melting point, cocoa butter is
  hard and brittle at normal room temperature.
• Help to prevent fat bloom

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Milk

• Compositions of cow milk

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Milk

• Compositions of lipids in milk

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Sugar

• Sucrose
• Combination of glucose and fructose
• Sugar bloom

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Chocolate manufacturing process
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Major function of these processes

• Fermenting and drying
• Removal of adhering pulp
• Removal of moisture
• Roasting
• Critical for flavor development
• Winnowing
• Removal of seed coat
• Size selection of nibs
• Milling
• Release of fat from cells

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Major function of these processes

• 5. Cocoa manufacture
• Production of additional fat (cocoa butter)
• 6. Refining
• Grinding of sugar particles
• 7. Conching
• Reduction in viscosity
• 8. Tempering
• Pre-crystallization process

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Chocolate flow properties

• Chocolate exhibits non-Newtonian properties
• For Newtonian fluid
• For Bingham fluid

Different types of rheogram (1) Newtonian (2)
Bingham (3) pseudoplastic (e.g. chocolate)
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• Steiners model for chocolate - adapted from
  Cassons model for printers ink

  where r, R are the inner and outer radius of
the cylinder respectively, ? is the angular
velocity, DN is the shear rate at the inner
cylinder.   ?CA (1/slope)2 (1/K1)2 plastic
viscosity according to Casson   ?CA (b/2)2
K02 yield value according to Casson
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Casson rheogram according to OICC
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Factors affecting the flow properties of chocolate

• Fat content

Influence of fat content on Casson parameters of
two milk chocolates with 0.25 lecithin.(1) Fine
chocolate with 5.7 particles gt 20?m (2)
moderaltely coarse chocolate with 16 particles gt
20?m.
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• Lecithin and other emulsifiers immediate
  reduction in viscosity
• Moisture content increases viscosity
• Particle size distribution

Influence of fineness on Casson parameters of two
milk chocolates with 0.25 lecithin. (1) 30 fat
(2) 32 fat
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• Temper increases viscosity
• Thixotropy decreases viscosity
• Vibration decreases viscosity
• Temperature

Influence of temperature on Casson parameters of
two milk chocolates. (1) 34 fat, without
lecithin (2) 30 fat, 0.15 lecithin
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Surface- active substances in chocolate
manufacturing

• Lecithin is the chief surfactant used
• The other surfactants are
• ammonium phosphatides (YN)
• polyglycerol polyricinoleate (PGPR)
• The chief function are
• reduce viscosity
• Reduce thickening due to moisture and temperature
• Modify the setting behavior of fat phase
• Flow characteristics of plain chocolate with
  added surface-active lipids

Casson plastic viscosity (poise)
Casson yield value (dynes/cm2)
Addition
0.3 soy lecithin 0.3 YN 0.3 sucrose
dipalmitite 0.3 PGPR 0.8 PGPR
6.1 10.3 8.6 32.5 20.3
92 30 166 25 0
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Influence of soya lecithin addition on Casson
parameters of two dark chocolates. (1) 33.5 fat,
1.1 water (2) 39.5 fat, 0.8 water
Viscosity reduction of dark chocolate by soya
lecithin and by synthetic active lipids .
Apparent viscosity determined at shear rate 15
s-1 and 50oC initial apparent viscosity before
addition 19.5 Pa s or 195 poises. (1) Soya
lecithin (2) phospholipid YN (3) sucrose
dipalmitate (4) polyglyceryl polyricinoleate,
PGPR
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Mechanism of viscosity reduction by lecithin

1. a monomolecular film is formed on the surface of
   the non-fatty particles by surfactant molecules.
2. reduction in internal friction by promoting the
   coating of sugar and cocoa solids by fatty
   medium.
3. increase in the amount of free cocoa butter in
   the dispersion medium by displacement from the
   surface of solids.
4. prevention of agglomeration of sugar particles
   and cocoa particles by break down of any
   lattice-type structure between them.
5. absorption of moisture

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Effect of lecithin on the stability of emulsions
Types of emulsions
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Chocolate an emulsion of hydrophilic sugar and
lipophilic cocoa particles in a continuous fat
medium
Molecular structure of main phospholipids found
in lecithin
Phospholipid structure at the interface of an
emulsion
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PACKAGING AND STORAGE

• METHOD OF WRAPPING
• MOLDED CHOCOLATE BLOCKS.
• CHOCOLATE COUNTLINES.
• BOXED CHOCOLATE.
• TWRIST WRAPPING.

• MATERIAL FOR PACKAGING
• ALUMINUM FOIL.
• REGENERATED CELLULOSE FILM (RCF).
• PLASTIC FILM.

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MOLDED CHOCOLATE BLOCK

• Protection against dirt, moisture and taint.
• It is more economical .
• Wide surface for labeling.

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CHOCOLATE COUNTLINES

• Normally wrap in pillow pack
• By heavy-backed foil, waxed paper or glassine.
• Protection against moisture vapor and taint.

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BOXED CHOCOLATE

• Usually, a thin layer of greaseproof film
  includes at the inner fitment.
• It prevents crushing of sweetness and cushioning.
• Protect against handling dirt.

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TWRIST WRAPPING

• In double end fantail form.
• By aluminum foil, backed and unbacked plain
  sliver, colored and printed film.
• Protection against dirt and taint.

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ALUMINUM FOIL

• Best barrier for water vapor and gas
  transmission.
• Thickness range from 7-12 ?m for pure aluminum.
• Combination with special alloy for extra
  strength.
• Thickness range 7-8 ?m.

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REGENERATED CELLULOSE FLIM (RCF)

• Packaging in flexible form.
• Usually coated or giving other treatments.
• Protection against moisture vapor and taint.
• PVDC for extra protection such as electrostatics.
• An advantage for tear strip product.

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PLASTIC FILM

• Three different forms polyethylene, polyvinyl
  chloride and polyester.
• Available in film or coating purposes.
• Protection against moisture, gas and ultraviolet.