Food Science Workshop

1. Food Science Workshop Martin Larter Grossmont College

2. Major food groups • Carbohydrates (aldehydes and ketones) • sugars, starches • provide energy • Lipids (carboxylic acids, esters) • fats and oils • provide energy and essential fatty acids (cannot be made by body) • Protein (amides) • meats and beans • provides amino acids for building proteins • Vitamins and minerals • Water

3. Carbohydrates • Composed of Carbon, Hydrogen, and Oxygen • Include sugars, starches, and structural materials (cellulose) • Contain -OH groups and a C=O group

4. Definitions • Monosaccharides - Simple carbohydrates that cannot be broken down by hydrolysis. • fructose, glucose, ribose • Disaccharides - Carbohydrates that can be hydrolyzed into two monosaccharide units. • sucrose, lactose, maltose • Polysaccharides - Carbohydrates that can be hydrolyzed to form many monosaccharide units. • starch, cellulose

7. Common Monosaccharides

8. Disaccharides • sugars consisting of 2 monosaccharides linked by glycosidic bonds.

9. Sucrose

10. Common Disaccharides

11. Figure 16.20: Two glucose molecules combine to form maltose and water. © 2003 John Wiley and Sons Publishers

12. Figure 16.22: Galatose, glucose, and lactose. © 2003 John Wiley and Sons Publishers

13. Benedicts Test for Reducing Sugars • Many sugars that have an available C=O group can be identified by a positive benedicts test. • Most sugars except for sucrose or table sugar can be identified by benedicts test.

14. Benedict's Test for Reducing Sugars Copper solutions turn red in the presence of a monosaccharide Can you tell which samples have a reducing sugar?

15. Polysaccharides • Polymers of simple sugars • Most common are Starch and Cellulose – made of glucose

16. Polysaccharides starch cellulose

17. Starches

18. Figure 16.21: Alpha-glucose and the chain of the starch molecule. © 2003 John Wiley and Sons Publishers

19. Figure 16.19: Beta-glucose and the chain of the cellulose molecule. © 2003 John Wiley and Sons Publishers

20. Figure 16.1: The color produced by an iodine solution distinguishes the starch of a potato from the cellulose of an apple. © 2003 John Wiley and Sons Publishers Courtesy Ken Karp

21. Lipids

22. Lipids • Biological molecules that are not soluble in water. • Two kinds • Saponifiable • Fats and oils • Non saponifiable • Cholesterol, waxes, and other interesting molecules

23. Figure 15.2: The general structure of a triglyceride. R, R’ and R” represent the long, fatty acid side chains. © 2003 John Wiley and Sons Publishers

24. Triglycerides

25. Figure 15.9: Molecular packing in glyceryl tristearate and glyceryl trioleate. © 2003 John Wiley and Sons Publishers

26. Saturated fat Unsaturated fat

27. Steroids • Cholesterol • most prevalent steroid • membrane component • combines with fatty acids and abnormal muscle tissue in atherosclerosis • Cholesterol is precursor to other steroids including bile salts, sex hormones, vitamin D, and adrenocortaid hormones.

28. Butcher Paper Test for Lipids

29. Sudan III is used to identify the presence of lipids • What to do. • To a test tube, add equal parts of test liquid and water to fill about half full. • If testing more than one liquid, label each test tube with a marker. • Add 3 drops of Sudan III stain to each test tube. Shake gently to mix. • A red-stained oil layer will separate out and float on the water surface if fat is present.

30. Proteins

31. Proteins • Composed of amino acids

32. Basic amino acid structure

33. Basic Amino Acid Structure

34. Amino Acids

35. Proteins – composed of amino acid chains

36. Primary structure • refers to the number and sequence of amino acids in a peptide chain • the unique sequences of each of the proteins determine their shapes and properties

37. Secondary structure • Refers to the ordered arrangement of the polypeptide backbone. • Alpha helix • Beta sheet

38. Alpha helix

39. Beta pleated sheet

40. Tertiary structure • Refers to the unique 3-D shape that results from the unique folding of the secondary structure.

41. Tertiary structure

42. Test For Protein • Biuret solution is used to identify the presence of protein. Biuret reagent is a blue solution that, when it reacts with protein, will change color to pink-purple.

43. Introduction to Food Science • Water • Water activity (free water) • Moisture content • Concentrations

44. Examples of Laboratories • Water • Determine moisture content • Concentration of constituents in water • Determine densities of water solutions

45. Thermochemistry • How do you find out how much energy you can get out of food? • Calorimetry

46. Coke Can Calorimeter

47. Energy Content of Food • Carbohydrates • 4 Cal/gram • Proteins • 4 Cal/gram • Proteins • 9 Cal/gram

48. Examples of Quiz Questions • Which of the following is NOT a carbohydrate? • Sugar • Starch • Cellulose • Amino acid • Which of the following contribute caloric intake in the human diet? (may be more than one answer) • Lipids • Minerals • Water • Proteins • Rank the following in terms of moisture content from highest (1) to lowest (4). • Maple Syrup • Potato chips • Dried Fruit • Fresh produce Fresh Produce>Maple Syrup>Dried Fruit>Potato Chips

49. Examples of Quiz Questions Different amounts of energy are supplied by proteins, carbohydrates, and fats. Carbohydrates and proteins provide 4 calories per gram and fat provides 9 calories per gram. You have a food product that has 5 grams of carbohydrates, 10 grams of protein, and 4 grams of fat per serving. • What is the total calorie content of one serving of this food product? • 5 * 4 = 20 • 10 * 4 = 40 • 4 * 9 = 36 • 36+20+40 = 96 calories • What percentage of the calories are from fat? • 4 * 9 = 36 • 36/96 = 0.375 or 37.5%