Linda Wozniewski

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Food Chemistry (B)

• Linda Wozniewski
• lwoz_at_iun.edu
• Sharon Ramsey

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Safety

• Students must wear
• Closed shoes
• Slacks or skirts that come to the ankles
• Lab coat or lab apron
• Indirect vent or unvented chemical splash proof
  goggles. No impact glasses or visorgogs are
  permitted
• Long-Sleeved Shirt (if wearing a lab apron)

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What Students MUST Bring

• Homemade viscometer
• Standard curve
• A writing instrument

What Students May Bring

• Non-programmable Calculator
• 3 ring binder with anything from any source
• Students are encouraged to experiment with a
  recipe to determine the effects of the various
  classes of ingredients on the final product.

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What Supervisors Will Supply

• Everything the student will need
• This may include
• Glassware
• Reagents
• Balances
• Hot plates
• Thermometers
• Probes
• Magnets
• Stirrers

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Main Focus

• Chemistry of Food
• How to prepare students
• Experiment ideas
• Resources

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Chemistry of Food

• a. Identify the sources of and understand the
  role of lipids, carbohydrates and proteins
  typically found in baked goods, and use tests to
  identify these compounds, including the
  Benedicts, Iodine and Brown Bag tests.
• b. When given samples of sweeteners, use the
  Benedicts test to identify reducing sugars.
• c. When given samples of baked goods ingredients,
  use the Biuret test to identify and rank the
  ingredients by protein content.
• d. When given formulations and processes,
  identify the error in the formulation and/or
  process used.
• e. Use standard labeling regulations to produce a
  label from information given.
• f. Determine the moisture loss and density of
  baked goods.
• g. Identify leavening agents using chemical
  tests, and understand the role of the leavening
  agents in baked goods.

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Before your event

• Research! Understand the science first
• Experiments
• Mixing method
• Ingredient chemistry
• Viscotester Production and Standard Curve

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Ingredients

• The right ingredients
• Liquids.
• Lipids
• Leavening agents
• Flours
• Sweeteners
• Must understand WHY you are using the
  ingredientwhat function does it provide?
• Teams are limited to listed ingredients

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List of Approved Ingredients
Liquids Lipids Leavening agents Flours Sweeteners
Water, Whole Milk (Cow or Goat), Skim Milk, Buttermilk, Almond Milk, Soy Milk, Coconut Milk, Eggs, Egg Substitute Vegetable oils, Shortening, Butter Margarines, Chocolate Flavoring Salt Vanilla Baking powder Baking soda Cream of tartar For State Nationals Essential Oils All purpose white flour Bread flour Cake flour Whole wheat flour Almond flour Coconut flour Corn Flour Rice Flour Sugar Brown sugar Honey Sucralose Aspartame For State Nationals Fructose
Each recipe must contain at least one egg or one
egg substitute equivalent.
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Carbohydrates

• Reducing sugars
• Examples glucose, lactose, fructose
• Non-reducing sugar
• Example sucrose

• Sugars
• Monosaccharides
• Glucose, Fructose
• Disaccharides
• Lactose (glucose and galactose) -milk
• Maltose (glucose and glucose) -
• Sucrose (glucose and fructose table sugar

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Carbohydrates

• Polysaccharides
• Examples
• 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

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Tests for carbohydrates

• Benedicts test for sugars
• Iodine test for starch

Positive Reaction
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Benedicts 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

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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

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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?

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Lipids

• http//www.wellsphere.com/healthy-cooking-article/
  butter-vs-shortening-in-baking/156136

• 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

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Proteins

• Proteins are made up of amino acids
• essential and nonessential
• Contains Nitrogen
• Protein can be found in the flour, egg and milk
  as well as other ingredients.

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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.
• Biurets Reagent is unstable, but can be mixed on
  the spot using NaOH Benedicts

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Leavening agents

• Used to produce a gas that 'lightens' dough or
  batter.
• used to raise baked goods.
• water a leavening agent (pie crusts, some
  crackers)
• air incorporated into batter (angel and sponge
  cakes)
• expand when heated and cause the raising of the
  dough or batter when gas is trapped in matrix of
  gluten and starch from flour

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Leavening agents

• Baking soda
• -NaHCO3
• Needs moisture plus an acid source such as
  vinegar, citrus juice, sour cream, yogurt,
  buttermilk, chocolate, cocoa (not
  Dutch-processed), honey, molasses (also brown
  sugar), fruits or maple syrup to react
• used to neutralize acids in foods
• around 4 times as strong as baking powder
• can cause soapy flavor in high amounts

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Leavening agents

• Baking powder
• NaHCO3 plus acidifier(s) and drying agent
  (usually an acid salt and cornstarch)
• can cause acidity and/or bitter off-flavor
• two acidifiers used in double acting to produce
  CO2 in two steps
• Reacts when moistened and also reacts when heated
• double-acting is the only commercial baking
  powder available today.

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Experimental Example Control

• 2 1/4 cups flour 1 1/3 cups sugar 3
  teaspoons baking powder 1/2 teaspoon salt 1/2
  cup shortening 1 cup milk 1 teaspoon
  vanilla 2 large eggs

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Effect of Ingredients
Batch Flour Leavening agent Sweetener Liquid Egg lipid Salt Vanilla
1 2 ¼ cups   3 tsps. baking powder 1 1/3 Cup 1 cup milk or sub. 2 large or substitute none ½ tsp. 1 tsp.
2 2 ¼ cups     3 tsps. baking powder 1 1/3 Cup 1 cup milk or sub. 2 large or substitute 3 Tbsp oil ½ tsp. none
3 2 ¼ cups   None 1 1/3 Cup 1 cup milk or sub. 2 large or substitute 3 Tbsp oil ½ tsp. 1 tsp.
4 2 ¼ cups   3 tsps. baking soda 1 1/3 Cup 1 cup milk or sub. 2 large or substitute 3 Tbsp oil ½ tsp. 1 tsp.
5 2 ¼ cups   3 tsps. baking powder 1 1/3 Cup 2 cup milk or sub. 2 large or substitute 3 Tbsp oil ½ tsp. 1 tsp.
6 2 ¼ cups   3 tsps. baking powder 2 1/3 Cup 1 cup milk or sub. 2 large or substitute 3 Tbsp oil ½ tsp. 1 tsp.
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Mixing Technique

• Incorporate ingredients
• Hydrate dry ingredients
• Experiment set 2 explores the best method to mix
  the batter

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Example Mixing Control

• Preheat oven to 350 degrees.  Line cupcake pans
  with paper liners.
• Combine flour, sugar, baking powder, and salt in
  a large mixing bowl.  Add shortening, milk, and
  vanilla.  Beat for 1 minute on medium speed. 
  Scrape side of bowl with a spatula.
• Add eggs to the mixture.  Beat for 1 minute on
  medium speed.  Scrape bowl again.  Beat on high
  speed for 1 minute 30 seconds until well mixed.
• Spoon cupcake batter into paper liners until 1/2
  to 2/3 full.
• Bake for 20 to 25 minutes or until toothpick
  inserted in center comes out clean.
• Cool 5 minutes in pans then remove and place on
  wire racks to cool completely.

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Mixing Technique
Batch Step 1 Step 2 Step 3 Step 4
1 Mix dry ingredients together Add liquid ingredients Using spoon, stir ingredients for 30 seconds Add egg. Use spoon to stir for 1 minute
2 Mix dry ingredients together Add liquid ingredients Pour into blender or use hand mixer and blend or mix 2 minutes Add egg. Use mixer or blender to blend for 1 minute
3 Mix dry ingredients together Add liquid ingredients Use whisk, stir ingredients 1 minute Add egg. Use whisk, stir ingredients 2 minutes
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Notebook

• Notebook keeping
• All experimental data and documentation should be
  recorded in notebook
• Must be 3-ring
• Must securely hold all items
• Dont erase in lab notebook!
• Document all references
• Use pen
• Can be brought to tournament as a resource to
  answer questions on the effects of mixing and
  ingredient changes

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Viscotester

• Made from 8 oz Styrofoam cup
• Heat 16 penny nail with tea candle for 1 minute
  (or until it gets too hot to hold)
• Punch hole from INSIDE into center bottom of cup
• Place tape over hole
• Time how long it takes for same amount of each
  standard liquid to break flow as it leaves
• When determining how much fluid to use, keep a
  couple of items in mind
• The larger the amount of fluid the less influence
  reaction time will have on error.
• The amount of fluid the event supervisor is
  likely to allow the team to have.

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Standard Curve

• Use same amount of standard fluids to calibrate
• Time how long it takes to break stream

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Standard Curve
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Viscosity

• Students need to investigate viscosity of their
  batters and compare to final results.
• The resistance of a fluid to deformation.
• Temperature dependent
• Dynamic or simple viscosity
• Kinematic viscosity ratio of viscosity/density
• Dynamic viscosity is measured in centipoise.

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Measuring Density

•  

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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

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Fiber

• Foods 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

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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.

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Resources

• For Event Supervisors
• http//mypage.iu.edu/lwoz/socrime/index.htm
• For Lesson Plans for classroom use
• http//mypage.iu.edu/lwoz/socrime/index.htm

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Questions

• Thank You

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Time to Play

• We can make viscotesters
• We can simulate a standard curve data collection
• We can find the viscosity of a batter
• We can find the density of muffins (substitute
  cupcakes)
• We can work with some tests from a simulated
  test.
• It is your option