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Chapter 4

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Chapter 4

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  1. Chapter 4 Nutritive Aspects of Food Constituents

  2. FOOD SUPPLIES: • Energy for all functions • Building blocks for growth & maintenance

  3. A Food ScientistMust Consider: • What nutrients do foods contain and what do we need? • What is the stability of these nutrients and how does food processing affect stability?

  4. Food as Fuel The major sources of energy are: • Carbohydrates • Fats • Proteins

  5. CALORIE • Amount of energy required to raise the temperature of one gram of water by 1oC KILOCALORIE • Unit used to express the energy value of foods • Equal to 1000 Calories

  6. Carbohydrates Fats Proteins 4 kcal/g 9 kcal/g 4 kcal/g ENERGY VALUETO HUMANS:

  7. ENERGY COSTS • Cheapest - Carbohydrates • Intermediate - Fats • Most Expensive - Proteins

  8. CARBOHYDRATES • Provide energy • Spare proteins • Help burn fats • Provide fiber

  9. PROTEINS • Provide essential amino acids • Can be used as energy • A complete protein contains all essential amino acids • Red meat, poultry, fish, milk & eggs are complete proteins • Vegetable sources are usually not complete

  10. FATS • Supply energy • Supply polyunsaturated fatty acids • One essential fatty acid = linoleic acid • Supply vitamins A,D,E & K • Insulate body from rapid temperature change

  11. Energy Carbohydrates Fats Glucose Fats Proteins Proteins Stored or Utilized as Consumed as

  12. VITAMINS

  13. VITAMIN A • Naturally occurs only in animals • Plants contain the precursor, B-carotene • Deficiency leads to blindness, abnormal bones, and membrane diseases of the nose, throat & eyes • Sources: liver, fish oils, dairy foods w/ fat, carrots, squash, sweet potatoes, spinach

  14. VITAMIN D • Formed in skin by conversion of cholesterol and other sterols by UV radiation • Increases absorption of Ca & P in intestine • Deficiency results in bone defects (rickets) • Most foods are low in Vitamin D • Milk is fortified

  15. VITAMIN E • Essential, but specific role unknown • May serve primarily as an antioxidant • Aids in Fe absorption • Stabilizes biological membranes • Sources: vegetable oils • Deficiencies are rare

  16. VITAMIN K • Essential for blood clotting • Sources: leafy vegetables • Bacteria in intestine synthesize K

  17. VITAMIN C • AKA Ascorbic Acid • deficiency causes fragile capillary walls, gum bleeding, loose teeth, bone joint disease • Easily destroyed by high temperatures • Sources: citrus fruit, tomatoes, green vegetables, potatoes due to high consumption rate

  18. VITAMIN B Complex Group • Thiamin (B1) • Riboflavin (B2) • Niacin (Nicotinic Acid) • B6 • Pantothenic Acid • B12 • Folacin • Biotin • Choline

  19. Thiamin (B1) • First of B vitamins to be discovered • Causes the disease known as “beriberi” • Necessary to utilize carbohydrates for energy • Sources: wheat germ, whole cereals w/ bran, liver, pork, egg yolk • Stable to heat in acid foods, but not in alkaline foods

  20. RIBOFLAVIN (B2) • Is the yellowish pigment in skim milk • Essential for oxidative cell processes • Deficiency results in skin disorders, cracking • Resistant to heat, but sensitive to light • Paper cartons are better for milk than clear plastic or glass

  21. NIACIN • Deficiency causes skin and mucous membrane disorders • Necessary for the respiration and oxidation of glucose • Sources: meat, fish, poultry, peanuts, legumes, whole grain cereals • Stable to heat, light and oxidation, but will leach from foods during processing

  22. VITAMIN B6 • AKA pyridoxine • Required for normal metabolism • Deficiency symptoms not well defined • Source: meat, liver, green vegetables, whole grain cereals

  23. PANTOTHENIC ACID • Deficiency symptoms not well defined • Available from a wide source of foods

  24. VITAMIN B12 • Required for RNA, DNA, fat and carbohydrate metabolism • Helps prevent anemias • Contains cobalt in its structure • Sources: liver, meats, seafoods • Not present in vegetables

  25. FOLACIN • Helps prevent anemias • Involved in synthesis of nucleic acids • Sources: animal and plant tissues

  26. BIOTIN • Active in metabolism of fatty acids and amino acids • Seldom in short supply • Synthesized by intestinal microbes

  27. CHOLINE • Component of cell membranes • Present in brain tissue • Involved in nerve impulse transmission • Seldom in short supply • Synthesized by intestinal microbes

  28. MINERALS

  29. Ca P Mg Fe Cu Co Zn Na Cl K I Fl MINERALS Plus Others

  30. FIBER • Maintains intestinal health • Lowers plasma cholesterol • Reduces incidence of colon cancer • Lowers insulin requirements of diabetics • Sources: cereal grains, fruits, vegetables

  31. WATER • 60% of human body is water • Is the primary solvent of biological systems • Removes wastes from body • Cools the body through evaporation • We drink 400 liters per year • Obtain 400 liters per year from food items