Linda Wozniewski [email protected] Sharon Ramsey Food Chemistry (B)
Food Chemistry (B)
description
Transcript of Food Chemistry (B)
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
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)
What Students MUST Bring Impounded
None Non-Impounded
Homemade viscometer Standard curve A writing instrument
What Students May Bring Non-programmable Calculator 1 sheet of paper on which anything is
acceptable
What Supervisors Will Supply Everything the student will need
This may include: Glassware Reagents Balances Hot plates Thermometers Probes Magnets Stirrers
Main Focus Chemistry of Food How to prepare students Experiment ideas Resources
Chemistry of Food a. Identify the sources of and understand the role of
lipids, carbohydrates and proteins typically found in cookies, and use tests to identify these compounds, including the Benedict’s, Iodine and Brown Bag tests.
b. When given samples of sweeteners, use the Benedict’s test to identify reducing sugars.
c. When given samples of cupcake ingredients, use the Biuret test to identify and rank the ingredients by protein content.
d. When given formulations, processes, and finished cupcakes, identify the error in the cupcake 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 cupcakes.
g. Identify leavening agents using chemical tests, and understand the role of the leavening agents in baked cupcakes.
Before your event Research! Understand the science
first Experiments – eight mandatory
(includingViscotester Production and Standard
Curve)
Ingredients The right ingredients
Liquids…. Lipids Leavening agents Flours Sweeteners
Must understand WHY you are using the ingredient…what function does it provide?
Teams are limited to listed ingredients
List of Approved IngredientsLiquids Lipids Leavening agents Flours Sweeteners
Water, WholeMilk (Cow or Goat), Skim Milk, Buttermilk, Almond Milk, Soy Milk, Coconut Milk, Eggs, Egg Substitute
Vegetable oils,Shortening, Butter Margarines,Chocolate
Baking powderBaking sodaCream of tartar
FlavoringSalt
All purpose white flourBread flourCake flourWhole wheat flourAlmond flourCoconut flourCorn FlourRice Flour
SugarBrown sugar Honey Sucralose AspartameVanillaFor State & NationalsFructosePowdered Sugar
Each recipe must contain at least one egg or one egg substitute equivalent.
Carbohydrates Carbohydrates
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)
Carbohydrates Sugars
Monosaccharides
Glucose, Fructose
Disaccharides Lactose (glucose
and galactose) -milk
Maltose (glucose and glucose) -
Sucrose (glucose and fructose –table sugar
Reducing sugarsExamples: glucose, lactose, fructose
Non-reducing sugar contains no hemiacetal groups.
Example: sucrose
CarbohydratesPolysaccharides 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
Tests for carbohydrates Benedicts test for sugars
Iodine test for starch
Positive Reaction
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
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
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?
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 3% 11% 29% 13%
Dark chocolate
0% 0% 34% 43%
Eggs 0% 0.3% 27% 10%
Soybean oil
0% 0% 11% 4%
Unsaturated Fats (Lipids) Have one
(monounsaturated) or more (polyunsaturated) carbon chains
This means there are one or more double bonds in the chain
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
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.
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
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
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
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.
Standard Recipe • 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
Effect of IngredientsBatch # Flour Leavening agent Sweeten
erLiquid Egg lipid Salt Vanill
a1 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.
Mixing Technique Incorporate
ingredients Hydrate dry
ingredients Experiment set
2 explores the best method to mix the batter
Standard Mixing 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.
Mixing TechniqueBatch # Step 1 Step 2 Step 3 Step 41 Mix dry ingredients
together
Add liquidingredients
Using spoon, stiringredients for 30 seconds
Add egg. Use spoon to stir for 1 minute
2 Mix dry ingredients together
Add liquidingredients 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 ingredientstogetherAdd liquidingredients Use whisk, stiringredients 1 minute
Add egg. Use whisk, stiringredients 2 minutes
Notebook/3-ring binder Notebook keeping (teams are encouraged to bake
goods, observe and record the differences caused by adjusting the ingredients from the Approved List of Ingredients). Optional but suggested for keeping records of all experimental data and documentation May be bound, spiral, or ring Must securely hold all items Don’t erase in lab notebook! Document all references Use pen
Notebook i. Experiment Name – 2 Points ii. Hypothesis – 4 points iii. Variables:
a. Controlled Variable(s) – 2 points b. Independent Variable(s) – 2 points c. Dependent Variable(s) – 2 points
iv. Materials (amount of each ingredient in grams or milliliters) – 4 points
v. Procedure – 10 points vi. Qualitative observations during the experiment (be
sure to include sensory score sheet) – 6 points vii. Quantitative observations during the experiment
(Data table, graphs-be sure to include nutritional calculations, viscosity testing, density, and crumb testing results) – 10 points
viii. Discussion of Results – 6 points ix. References – 2 points
Cupcake Use any combination of ingredients from the
approved list as well as physical parameter changes (temperature, cupcake lining materials, etc.) to formulate an ideal team cupcake. Teams may choose variables used in the first two experiments or use new variables. If a recipe from a cookbook or web site is used as a starting source, the source must be listed in the notebook.
Aiming for a density of 0.3 g/ml Aiming for less than 0.3% of the mass of the
cupcake to be left on liner or in crumbs when liner taken off
Must have nutrition food label
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.
Standard Curve Use same amount of standard fluids
to calibrate Time how long it takes to break
stream
Standard Curve
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 Shear viscosity – reaction to a shearing
stress (pumping, spraying, etc.) Must know general nomenclature
Measuring Density
Density Score Sheet Students should measure the density
of each of their experimental cupcakes and record
Suggested Density Suggested Score.28-.329 5
.25-.279 or .32-.359 4
.21-.249 or .36-.389 3
.19-.209 or .319-.42 2Less than .19 or greater
than .421
Nutrition Students will create a food label for
their cupcakes properly indicating serving size, calories, amount fat, unsaturated fat, saturated fat, carbohydrates, sugars, fiber, and protein, as well as accompanying daily value percentages.
Students are NOT to be scored on how healthy the cupcake is, only on their ability to identify its role in a healthy diet.
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
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
Nutritional labeling1) Fill in the following blanks.
a) There are ___ Calories/gram of fat.b) There are ___ Calories/gram of carbohydrate
c) There are ___Calories/gram of proteind) There are ___Calories/gram of water
2) Use the nutritional label given for information to answer the following questions:
a) Calculate the Calories in one serving of this product.
(1)Calories from Fat(2)Calories from Protein(3)Total Calories in one serving
b) What percent of the carbohydrate Calories come from fiber?
c) If the daily value of iron is 18 mg per day, calculate the amount (in mg) of iron in one bar of this product.
Nutrition Scoring The labels will be scored as follows:
i. Creative Cupcake name (5 points) ii. Ingredient List in correct order (15
points) iii. Nutritional Facts in correct order (15
points) iv. Package Weight (10 points) v. Company (team) Name and Address in
the correct location (5 points) vi. Label Information matches notebook
(10 points)
Sensory Score SheetAttribute Score (Circle for each attribute listed)Flavor
Aroma 1Terrible
2
3Average
4 5Very Pleasing
Starch
1Raw or burned
2Under or over
cooked
3Slightly under or over cooked
4Pleasingly cooked
5Very
Pleasingly cooked
Dairy/Milky
1Spoiled
2Moderate off-
flavor
3 Slightly off
flavor
4OK
5Pleasant
Sweetness
1Way too much or too little
2Moderately too much or too
little
3Slightly too sweet or too
tart
4About right
5Perfect sweetness
Vanilla
1Way too much or not enough
2Moderately too much or too
little
3Slightly too much or too
little
4About right
5Excellent
Texture
Surface1
Really rough2
Somewhat rough3
Moderately rough
4Slightly smooth
5Smooth
Moisture
1Dry
2Moderately dry
3Somewhat dry
4Somewhat moist
5Moisture just
right
Cohesiveness1
Really gummy2
Somewhat gummy3
Slightly gummy4
Falls apart easily
5Just right
Stickiness
1Really sticky
2Moderately sticky
3Somewhat sticky
4Slightly sticky
5Just right
Circle any of the following if present
Sour
Bitter
Astringent
Gritty
Oxidized (paint) flavor
Resources For Event Supervisors
http://mypage.iu.edu/~lwoz/socrime/index.htm
For Lesson Plans for classroom use http://mypage.iu.edu/~lwoz/socrime/ind
ex.htm
Questions
Thank You
Time to Experiment 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 We can work with some tests from a
simulated test. It is your option