1. Colloidal and surface phenomenal aspects of Ice cream

2. History Little is known Introduced from Europe Records indicate served by Governor Bladen of Maryland in 1700 In 1832 a recipe and manufacturing methods were invented First large scale ice cream plant established in 1851 in Baltimore

3. Design considerations Flavor Texture Body Melt characteristics Color Inclusion of candies and fruit

4. Ingredients contributing to properties Fat and water Emulsifiers Stabilizers Proteins Sweeteners Other elements

5. Fat and water Fat –Large molecule –Triacylglyceride –Nonpolar –Vanderwaals Water –Small molecule –Hydrogen dioxide –Polar

6. Emulsion –Mechanically dispersed –Low internal phase ratio –Low solubility (14w/w) –Droplets.1-10micro meter –Fat network Large surface to volume ratio Milk fat has wide melting pt around 40 C This partial crystallinity adds to ability to network

8. Additional properties of fat Produces characteristic smooth texture Adds richness and sweetness in flavor Aids in dissolving some flavors and vitamins

9. Emulsifiers Emulsion stabilizers Decrease interfacial tension from 15-25 to less than 10dynes/cm Before freezing- decrease ability of fat to coalesce During freezing-cause partial destabilization of lipid phase During whipping- cause partial coalescence When emulsifier conc. Increases fat penetrates air phase more Results in stable air phase, stable fat network, smoothness in texture

10. Resulting benefits Decreased freezing time Increase minuteness of components Increase stiffness Increase uniformity of melting

11. Types Original:Lecithin Found in egg yolks and soybeans Phospholipids Are modified for polarity and hydrophobicity

12. Types Poly sorbate Sorbitan ester Smaller in MW Produces low tension Very thin membrane Maximum fat destabilization Also drying agent-adsorbs some water

13. Types Mono and Di glycerides Derived from partial hydrolysis of fats and oils

14. Stabilizers Effect ice/ water mixture Polysacharides – large hydration capability Increace viscocity decreacing diffusional abilities Stabilize foam phase Do not actively effect interfacial tension but decreace the avaliability of water indirectly effecting tension Stabilize emulsion Increace smoothness

15. Stabilizers cont. Decrease size of ice crystals –Decrease diffusion and the total growth –Depresses freezing point as water is removed from solution maintaining water phase –Decreases “heat shock” through this mechanism Increase stiffness of product Decrease moisture migration out of product

16. Types Carboxymethyl cellulose (CMC) Locust Bean Gum Carrageenan Guar gum Geltatin

17. Proteins Large polymers Both hydrophobic and hydrophilic Extend on interface Create micelles Both stabilizers and emulsifiers increase protein concentration Increase viscosity Critical protein depletion before partial coalescence Increased hydrophobicity at interface yielding stability Decrease melting rates Increased shape retention

18. Types Caseins –80% total milk protein –Phosphoproteins precipitated at 4.6 ph –Micelles –Preferentially diffuse out of lipid phase Whey –Soluble at low ph –Globular

19. Sweeteners Taste Improve texture and palatability Also depresses freezing point

20. Other ingredients and factors –Ions effect destabilization, wetness influence electric double layer and repulsion citrate and phosphate increase protein aggregation and decrease coalescence Ca and mg decrease aggregation and promote coalescence –Additives (nuts,candy etc.) add crystal centers, also may effect moisture content –Phase volume –Temperature (freezing, mixing, packaging)