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

  2. 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)

  3. 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.

  4. What Supervisors Will Supply • Everything the student will need • This may include: • Glassware • Reagents • Balances • Hot plates • Thermometers • Probes • Magnets • Stirrers

  5. Main Focus • Chemistry of Food • How to prepare students • Experiment ideas • Resources

  6. 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 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 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.

  7. Before your event • Research! Understand the science first • Experiments • Mixing method • Ingredient chemistry • Viscotester Production and Standard Curve

  8. 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

  9. List of Approved Ingredients Each recipe must contain at least one egg or one egg substitute equivalent.

  10. 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

  11. 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

  12. Tests for carbohydrates • Benedicts test for sugars • Iodine test for starch Positive Reaction

  13. 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

  14. 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

  15. 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?

  16. 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

  17. 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.

  18. 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

  19. 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

  20. 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

  21. 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.

  22. 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

  23. Effect of Ingredients

  24. Mixing Technique • Incorporate ingredients • Hydrate dry ingredients • Experiment set 2 explores the best method to mix the batter

  25. 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.

  26. Mixing Technique

  27. Notebook • Notebook keeping • All experimental data and documentation should be recorded in notebook • Must be 3-ring • Must securely hold all items • Don’t 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

  28. 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.

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

  30. Standard Curve

  31. 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.

  32. Measuring Density

  33. 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

  34. 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

  35. 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.

  36. 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

  37. Questions • Thank You

  38. 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