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Food Technology and Engineering
Transcript of Food Technology and Engineering
Investigation of Ice Cream, Gelato, Frozen Yogurt & Sorbet
What's the difference?
Structure of Ice Cream
What is ice cream??
Differences in Rheology
Chemical Composition of Frozen Desserts
Importance of Sugar
Other Considerations of Frozen Desserts
– aroma and taste component
-fat or water soluble
-reasons for addition:
or make uniform
Milk, eggs, sugar, additives blended for 6-8 minutes
break the fat particles down into many small droplets (1micron diameter)
hot mix is forced through a small valve under high pressure (up to 150 atm).
Temperature: 80.5 Degrees
Holding time: 31s in the Pasteurization Tube
Examine 4 frozen desserts
Ice Cream, Gelato, Frozen Yogurt & Sorbets
Discuss and compare
Rheology, Chemical and Nutritional Composition, Manufacturing & Innovative Ideas
A micro structure of…
Viscous matrix of sugars, polysaccharides and milk proteins
Mix is cooled and held at between 0 and 4 °C
Two important processes to stabilize air bubbles later:
Emulsifiers adsorb to the surface of the fat droplets, replacing some of the milk protein.
Fat inside the droplets begins to crystallize.
> 6hours for extruded products
2 hours for most products
Creates ice-crystals, air bubbles and the matrix by simultaneously
Beating (shear stress)
5 atm pressure inside barrel
Barrel wall temperature -30°C
Residence time 30-60s
Increases the amount of partially coalesced fat and makes the ice cream stiffer
Smaller the air bubbles
Slow down coarsening
Cold air (- 30 °C to - 45 °C) blown over ice cream
Low temperature and fast air flow increase rate of heat removal
Do not contain fat, so do not need aging
Barrel pressure of 2-3 atm is used to achieve the required overrun
On exit from the factory freezer, a water ice slush is produced, with an ice phase volume that is determined by the outlet temperature.
Desserts for diabetics
Desserts for those suffering from Lactose intolerance
Desserts for the Health Conscious
No sugar added - Use of substitutes
Natural sweeteners- Xylitol, found in corn, berries and mushrooms
Artificial sweeteners such as Sucralose (Splenda)
1. To retain the same “sweetness” level: Xylitol's sweetening power is the same as that of sucrose (table sugar)
2. To avoid compromising health: The body does not require insulin to metabolize xylitol.
Artificial sweeteners do not affect blood sugar levels. They cannot be broken down by the body and pass through our systems without being digested
Frozen Desserts for Diabetics
Natural sweeteners are safe for consumption but artificial sweeteners need to be approved as they may have side effects
Example: ADI for Sucralose is 5 milligrams per kilogram, or the equivalent of 6 cans of diet pop
“It is quite simply a delicious, creamy vanilla ice cream. It isn't too sweet and to be honest you would be hard pressed to distinguish this from any good quality creamy vanilla ice cream."
Frozen Desserts for Diabetics
Lactose intolerance means the body cannot easily digest lactose, a type of natural sugar found in milk and dairy products.
Lactose free products- non dairy
Two methods to allow consumption of frozen desserts for those who are lactose intolerant
1. Use of dairy free products- substitutes
2. Treatment before production.
Frozen desserts for Lactose Intolerance
Low calories desserts - replacing cream and eggs with a milk substitute
Use of sugar-free products
- Sweeteners such as monk-fruit
Reducing the fat percentage
- Reduced, Light, "Low fat" Frozen Dairy
Frozen Desserts for the Health Conscious
Frozen desserts is a growing industry
Recorded sales worth $25.1 billion in 2011
Constant progression and new innovations to meet the changing market
Manufacturing and Processing
Differences in Processing
Ingredients serve as purpose in:
the manufacturing process
enhance flavours and textures
Primary Ingredients in Frozen Desserts
percentage of water frozen
- dissolving medium for rest of ingredients
-forms ice crystals
- lowers freezing point of water
-sweetener and texture enhancer
Milk Fat (1-20%)
- assists in aeration of product
-adds density,smoothness and flavour
contributes to consistency, texture and volume
-add viscosity, control ice crystallization
E.g. Non-fat Milk Solids
- protein source (surface active)
impede water-fat seperation
decrease surface tension
E.g. Lecithin (egg yolk)
Food Taste & Rheology