Colloid and surface phenomena aspects of Chocolate

1. Colloid and surface phenomena aspects of Chocolate CE 457/527 Chin Kok Ooi Teck Yu Sia Anshu Verma Shushan Munshi

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

3. Marketing • Designing chocolates • Energy • Size • Price • Efficiency • Legal requirements • Advertisement

4. Components and Compositions The ingredients of chocolate Cocoa, cocoa butter, milk and sugar Additional ingredients Lecithin(emulsifier) and flavoring agents

5. Cocoa and Cocoa butter • Both are obtained from the seeds of ‘Theobroma Cocoa’. • ‘Cocoa beans’ grow in pods.

6. Composition Per cent Composition Per cent Moisture 6.3- 8.5 Cocoa Red 2.5- 5.0 Fat 46.9- 52.1 Ash 2.9- 4.8 Albuminoids 11.6- 21.1 Astringent matters 7.2- 8.6 Cellulose 3.3- 6.6 Cane sugar Alkaloids 0.3- 0.5 Starch 8.7- 12.6 Cocoa and Cocoa butter • General compositions of cocoa bean

7. 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.

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

9. Component Content (% w/w) Water 87.3 Proteins (caseins & whey proteins) 3.3 Fat 3.9 Lactose 4.6 Minerals 0.65 Others (vitamins, organic acids, etc) 0.32 Milk • Compositions of cow milk

10. Component Content (% of total fat) Triglycerides 96-99 Diglycerides 0.3-1.6 Monoglycerides 0.02-0.1 Free fatty acids 0.1-0.4 Phospholipids 0.2-1.0 Sterols 0.2-0.4 Cerebosides 0.01-0.07 Milk • Compositions of lipids in milk

11. Sugar • Sucrose • Combination of ‘glucose’ and ‘fructose’ • Sugar bloom

12. Fermented and Dried Beans Cleaning Roasting Breaking and Winnowing Nib-Shell Mixtures Nib Shell Germ Separation Germ-free Nib Milling Cacoa-Mass (Chocolate liquor) Cocoa manufacture Chocolate manufacture Alkalization Addition of Sugar, Flavor, Milk etc. and Cocoa Butter Removal of excess moisture Mixing Fat Pressing Refining Press Cake Cocoa Butter Conching Breaking Tempering Grinding Molding Enrobing Sifting Plain or Milk Chocolate Chocolate -coated goods Cocoa Powder Chocolate manufacturing process

13. 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

14. 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

15. D 1 2 3 o  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)

16. Steiner’s model for chocolate - adapted from Casson’s model for printer’s 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

17. b=2K0 Casson rheogram according to OICC

18. 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 > 20m; (2) moderaltely coarse chocolate with 16% particles > 20m.

19. 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

20. 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

21. 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

22. 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 Viscosityreduction 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

23. Mechanism of viscosity reduction by lecithin • a monomolecular film is formed on the surface of the non-fatty particles by surfactant molecules. • reduction in internal friction by promoting the coating of sugar and cocoa solids by fatty medium. • increase in the amount of ‘free’ cocoa butter in the dispersion medium by displacement from the surface of solids. • prevention of agglomeration of sugar particles and cocoa particles by break down of any lattice-type structure between them. • absorption of moisture

24. Oil Creaming Sedimentation Coalescence Separation Creaming of emulsions: four phases Lecithin molecule at interface between water and oil oil-in-water water-in-oil Effect of lecithin on the stability of emulsions Types of emulsions

25. Chocolate – an emulsion of hydrophilic sugar and lipophilic cocoa particles in a continuous fat medium Molecular structure of mainphospholipids found in lecithin Phospholipid structure at the interface of an emulsion

26. METHOD OF WRAPPING: MOLDED CHOCOLATE BLOCKS. CHOCOLATE COUNTLINES. BOXED CHOCOLATE. TWRIST WRAPPING. MATERIAL FOR PACKAGING: ALUMINUM FOIL. REGENERATED CELLULOSE FILM (RCF). PLASTIC FILM. PACKAGING AND STORAGE

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

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

29. 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.

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

31. 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.

32. 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.

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