1. Linda Wozniewski lwoz@iun.edu
Food Chemistry (B)
Linda Wozniewski

2. Disclaimer
This presentation was prepared using draft rules.  There may be some changes in the final copy of the rules.  The rules which will be in your Coaches Manual and Student Manuals will be the official rules

3. Safety Students must wear: Closed shoes
All skin from neck to toes covered
Lab coat or lab apron
Indirect vent or unvented chemical splash proof goggles.
All skin from neck to wrists covered
Long hair (shoulder length or longer) must be tied back.
Visorgogs now permitted

4. What Students MUST Bring
Safety gear
Cheesecloth
pH paper
Writing implement
Paper towels
Laboratory notebook – impounded
Graduated cylinders
Beakers
Spoons
Equipment to do activities
Cups
ml plastic bottle with lid
Plastic bags

5. What Supervisors Will Supply
Dairy products
Balance
Thermometers
Everything the student will need
Lemon juice or vinegar if doing cottage cheese
Ice, salt, and sugar if doing ice cream
Anything else that may be needed if any other tests are to be done.

6. What Students May Bring
Graphing Calculator
5 sheets of paper (both sides) on which anything is acceptable

7. Main Focus Chemistry of Food How to prepare students Experiment ideas
20% Laboratory Notebook
40% Competition task
40% Written test
How to prepare students
Experiment ideas
Resources

8. Chemistry of Food
Identify the sources of and understand the role of lipids, carbohydrates and proteins typically found in foods, and use tests to identify these compounds, including the Benedict’s, Iodine and Brown Bag tests.
When given samples of sweeteners, use the Benedict’s test to identify reducing sugars.
When given samples of ingredients, use the Biuret test to identify and rank the ingredients by protein content.
Use standard labeling regulations to produce a label from information given.
Organic reactions such as esterification, fermentation, pickling, fat bonding
Identify leavening agents using chemical tests
Saturated and unsaturated fats
Chemical structure of sugars, starches, fats, and proteins
Essential fats, vitamins, protiens

9. Chemistry of food, con’t.
How cooking changes food chemically
Allergens in foods
Food preservation
RDA (recommended daily allowance) of essential minerals and vitamins and the consequences of not having them

10. Before your event Research! Understand the science first Experiment:
How does the pH (how much acid should you add) of the milk effect the production of cottage cheese?
How does the temperature of the cream effect the percentage of fat?
How does the percentage of fat in the milk effect how high a tower you can make?
How does the amount of time you leave the ice cream in the ice effect the height of the tower?

11. Ingredients The right ingredients
Liquids….
Lipids
Sweeteners
Must understand WHY you are using the ingredient…what function does it provide?

12. Carbohydrates Carbohydrates Basic unit – monosaccharide
Cox(H2O)y carbon along with hydrogen and oxygen in the same ratio as water
Basic unit – monosaccharide
Multiple units –
disaccharide (2)
trisaccharide (3)
oligosaccharide (2-10)
polysaccharide (>10)

13. Carbohydrates Sugars Reducing sugars Monosaccharides
Examples: glucose, lactose, fructose
Non-reducing sugar contains no hemiacetal groups.
Example: sucrose
Sugars
Monosaccharides
Glucose, Fructose
Disaccharides
Lactose (glucose and galactose) -milk
Maltose (glucose and glucose) -
Sucrose (glucose and fructose –table sugar

14. Carbohydrates Polysaccharides Examples: Branched vs. linear
starch - glucose polymers, found in plants
cellulose –found in plant fibers, insoluble
Pectin-units are sugar acids rather than simple sugars, found in vegetables and fruits
Branched vs. linear
Starches are a mixture of branched (amylopectin) and linear (amylose) polysaccharides

15. Fiber Non-starch polysaccharides (cellulose, etc.)
Food not digested by human digestive system
Two types
Soluble Fiber-helps regulate blood sugar
Found in Oats & Oat Bran, some Fruits & vegys
Insoluble Fiber-helps clean out colon
Found in whole wheat, some fruit skins and vegys.
Cellulose

16. Tests for carbohydrates
Benedicts test for sugars
Iodine test for starch
Positive Reaction

17. Benedict’s Test
The Benedict's test allows us to detect the presence of reducing sugars (sugars with a free aldehyde or ketone group).  All monosaccharides are reducing sugars.  Some disaccharides are also reducing sugars.  Other disaccharides such as sucrose are non-reducing sugars and will not react with Benedict's solution.  Starches are also non-reducing sugars. 
The copper sulfate (CuSO4) present in Benedict's solution reacts with electrons from the reducing sugar to form cuprous oxide (Cu2O), a red-brown precipitate.
The final color of the solution depends on how much of this precipitate was formed, and therefore the color gives an indication of how much reducing sugar was present if a quantitative reagent was used.
With increasing amounts of reducing sugar the result will be:
green yellow orange red

18. Iodine Test
The Iodine test is used to test for the presence of starch.
Iodine solution – Iodine is dissolved in an aqueous solution of potassium iodide - reacts with starch producing a deep blue-black color.
Although the exact chemistry of the color change is not known, it is believed that the iodine changes the shape of the starch to change the color

19. Lipids
Present as fats extracted from plants or animals (butter, vegetable oil) or as constituents of food (chocolate)
Contributions to foods: texture and flavor
Contain only Carbon, hydrogen and oxygen
Most common form for lipid in foods is as a triglyceride
What difference in texture would you see substituting vegetable shortening or vegetable oil for butter in the formulation?

20. Saturated Lipids (Fats)
Saturated fats have no double bonds in any of the fatty acid chains in the triglyceride hence it is saturated with hydrogen.
Considered not heart healthy
Food
Lauric acid
Myristc acid
Palmitc acid
Stearic acid
Coconut oil
47%
18% 9% 3%
Butter
11%
29%
13%
Dark chocolate 0%
34%
43%
Eggs
0.3%
27%
10%
Soybean oil 4%

21. Unsaturated Fats (Lipids)
Have one (monounsaturated) or more (polyunsaturated) carbon chains
This means there are one or more double bonds in the chain

22. Lipids
Conversion between solid structure to a liquid state is called the melting point
How would changing the melting point of the lipid used change the cookie texture?
Brown Bag Test

23. Proteins Proteins are made up of amino acids
essential and nonessential
Contains Nitrogen
Proteins are made up of long intricate folded chains of amino acids
Protein can be found in the flour, egg and milk as well as other ingredients.
When foods cook, the proteins denature

24. Proteins
Biuret Test
The Biuret Reagent is made of sodium hydroxide and copper sulfate. The blue reagent turns violet in the presence of proteins, and the darker the purple color, the more protein is present.
Biuret’s Reagent is unstable, but can be mixed on the spot using NaOH & Benedicts

25. Notebook Notebook keeping 20% of score
All experimental data and documentation must be recorded in notebook
We are using a standard page
Document all references
Use pen
Provide Pictures of product/experiment
Pages are available on-line

26. Experiment Form- Include picture of product/experiment on back of page
Food Science B-Dairy
Experiment Form- Include picture of product/experiment on back of page
Team ___________________________________ Date _________________________
Team Members ______________________________ _________________________
Product to be made: ______________________________________________________________
Independent Variable: _____________________________________________________________
Dependent Variable:_______________________________________________________________
Controls: ______________________________________________________________________
_______________________________________________________________________
Results: _______________________________________________________________________
Analysis: ______________________________________________________________________
______________________________________________________________________

27. Nutrition
Calorie - amount of heat required to raise the temperature of 1 gram of water 1 degree Celsius.
Kilocalorie (1000 calories) is the unit commonly used to represent energy values of foods -or Calorie with a C instead of a c
Not all carbohydrates (or fats, or proteins) yield the exact same amount of energy when burned in a calorimeter, so common averages from studies (in kcal/g) are used
Carbohydrates average 4.1 kcal/gram in a bomb calorimeter, are about 98% digestible and yield 4 kcal/g when consumed
Proteins average 5.7 kcal/g in a bomb calorimeter, are not as easily digested and yield an average of 4 kcal/g when consumed
Lipids average 9.5 kcal/g in a bomb calorimeter, are 95% digested and yield an average of 9 kcal/g when consumed
Fats (lipids) are the most concentrated source of food calories
Carbohydrates are the cheapest source of calories, proteins the most expensive

28. Nutritional labeling Fill in the following blanks.
There are ___ Calories/gram of fat.
There are ___ Calories/gram of carbohydrate
There are ___Calories/gram of protein
There are ___Calories/gram of water
Use the nutritional label given for information to answer the following questions:
Calculate the Calories in one serving of this product.
Calories from Fat
Calories from Protein
Total Calories in one serving
What percent of the carbohydrate Calories come from fiber?
If the daily value of iron is 18 mg per day, calculate the amount (in mg) of iron in one bar of this product.

29. Resources For Event Supervisors For Lesson Plans for classroom use
For Lesson Plans for classroom use

30. Questions
Thank You

31. Time to Play
We will make:
Ice Cream
Cottage Cheese
Butter

32. Ice Cream Milk should be cold, so we will do this first
The milk has already been measured out to 125 ml
The sugar has already been measured out to 15 ml (1 tablespoon)
Add the milk and sugar to the pint plastic bag and manipulate to dissolve the sugar
The salt has already been measured out to 90 ml (120 g)
Fill the gallon plastic bag ½ full of ice & add salt

33. Ice Cream con’t Mix the ice and salt Add the bag of milk and sugar
Agitate for 15 minutes. (Switch off people agitating)
Pour out the ice cream into a plastic cup or beaker and see how high a tower you can make

34. Butter The 150 ml of heavy cream has already been measured out.
Find the mass of the cream
Add this to the 500 ml water bottle
The temperature should be about 13 ºC
Put on the cover and shake horizontally vigorously for about 15 minutes
The contents will become solid and then liquid again
Pour off the liquid

35. (Mass of fat/mass of cream)*100
Butter continued
Pour of all liquid and rinse with cold water (someone will have to go to the bathroom to do this I am afraid)
Put the butter in a beaker and work until the liquid is out
Find the mass of the butter
Calculate the % of fat
(Mass of fat/mass of cream)*100

36. Cottage Cheese 150 ml of milk has already been measured out.
Find the mass of the milk
The milk needs to be about room temperature
Add ~6 ml of vinegar, 1 drop at a time
Swirl gently or mix gently
Allow to sit for five minutes
Put a piece of cheese cloth over a beaker and secure it with a rubber band.
It is best if the cheese cloth is not taught

37. Cottage Cheese Pour the cottage cheese curds into the cheese cloth
After 15 minutes gather up the cheese cloth and gently squeeze to remove the rest of the whey
Spread the cheese cloth out to dry
Determine the mass of the casein
Determine the % curds.