Domain I-Topic A #1 (a: 1-3)

Physical and Chemical properties of food-

1)  Meat, Fish, Poultry

  1. Contain both muscle and connective tissue
  2. Protein in muscle consist of enzymes an myofibrillar proteins
  3. Principle myofib. protein is myosin- others include actin and tropomysin (among others)
  4. Connective tissue- composed of proteins (elastin, reticulin, ground substance, and collagen)
  5. Triglycerides containing a variety of fatty acids are the predominant form of lipids in meats
  6. Others are – chol, glycolipids, phosphoglycerides, plasmalogens, and sphingomyelins
  7. these constitute fat depots that are imbedded in connective tissue
  8. Hemoglobin and myoglobin are 2 principle non-cont. pigments in red meats.
  9. Myoglobin in the ferrous (2+) form is the purple-red color of fresh meat
  10. Exposure to air adds two atoms of O2 to make oxymyoglobin, a bright red pigment
  11. Metmyoglobin, a brownish red pigment forms if iron is oxidized to the ferric (3+) state.
  12. Heating causes gradual changes in pigment to the gray-brown compound- denatured globin hemichrome
  13. w/ addition of nitrites, nitric oxide myobglobin forms during the curing of meats->nitric oxide myochrome when heated-> results in stable reddish color of cured meats
  14. Poultry and Fish generally have little pigmentation
  15. Poultry may have some from reddish color from hgb
  16. Fish may have dark muscles colored by myoglobin
  17. Salmon red is from astaxanthin (a carotenoid pigment)
  18. Major changes with slaughter
  19. Rigormortis- rate, on set, and passage of rigor are a result of the species and the physical condition and time of slaughter
  20. Quality of meat judged on basis of texture, marbeling, and palatability
  21. Yield is based on amount of muscle in relation to bone and fatty deposits
  22. Cuts identifiable on size of the cut, color, muscle present, and bone shape
  23. W/ heat
  24. Muscle fiber shrink lengthwise and lose water binding capacity
  25. Collagen changes to gelatin
  26. Cooking losses vary with temp, method of heating, final temp of meat among others
  27. Less tender meats-> braising, stewing
  28. Fish may be poached
  29. Dry heat methods for tender cuts: roasting, broiling, pan broiling, pan frying, deep fat frying, microwave cooking
  30. Meat substitutes
  31. Texture soy protein can be made into meat analogs
  32. Tofu, TVP, Tempeh are examples

2)  Eggs

  1. Structure
  2. Multilayered yolk encased in vitellene membrane and a chalazeferous layer, all of which is surrounded by 3 layers of albumin
  3. An inner membrane and outer membrane layer separate contents of egg from porous shell
  4. Egg white
  5. Largely water and protein
  6. B vitamins
  7. 1 egg white has more pro than 1 egg yolk
  8. Yolk
  9. Significant amt of lipids
  10. Half as much pro as white
  11. Among lipids in yolk is lecithin (an emulsifying agent), cholesterol, fat sol vits, iron
  12. Changes in egg during prolong storage
  13. Increase in air cell size
  14. pH increases as egg ages
  15. yolk membrane weakens
  16. whites become thinner
  17. Difference btwn egg substitute and egg
  18. Egg subs are egg whites with coloring- no fat or chol
  19. More firm b/c no fat, not as smooth product
  20. Difference btwn egg protein and wheat protein
  21. Difference in coagulation temp
  22. Difference in elasticity
  23. Quality of protein lower in wheat
  24. Egg has ability to act as leavening agent
  25. Eggs deteriorate easily
  26. Must be stored under refrigeration or processed for longer storage
  27. Processing includes pasteurization, drying, and freezing
  28. Eggs are great mediums for growth of microorganisms
  29. Eggshells should be uncracked, cleaned, and sanitized prior to refrigerated storage
  30. Adequate heat needed to assure safety
  31. Eggs are important as emulsifiers, thickening, agent, and as foaming agents

3)  Milk and Dairy Products

  1. Milk contains <4% fat (more than half is saturated)
  2. 88%water, 5%CHO, 3.5%Pro
  3. Lactose is the CHO of milk
  4. Casein is the protein complex comprising the curd, whey is the protein complex
  5. Pasteurization
  6. Heat treatment that kills microorganisms in milk
  7. Hold- milk is heated to 63 degrees C held 30 min cooled to 10 deg. C
  8. HTST- milk is heated to 72 deg C, held 15 sec, cooled to 10 deg C (high temp, short time)
  9. UHT- milk heated to 138 deg C, held 2 sec (kills all microorg.) makes possible to store milk in closed containers at room temperature for 6 months
  10. Homogenization- forcing milk through tiny apertures to modify size of fat globules and alter protein slightly
  11. Evaporation and drying are two forms of preserving milk
  12. Fermentation is used to alter chemical and physical properties of milk products (i.e. buttermilk)
  13. Cheese is made by forming curd, draining whey and then heating and pressing gently to achieve moisture level
  14. Natural cheese often aged to modify flavor and texture
  15. Natural cheese is made by clotting mild to form a cured and then concentrating curd by draining the whey (no additives) examples- cheddar, provolone
  16. Processed- emulsifiers added to natural cheeses making them softer, easier to cook with, and reduces spoilage potential
  17. Processed cheese food processed chesses with 4% higher moisture content than processed cheese. Not allowed in WIC program (examples- Velveeta- wrapped slices)
  18. Processed cheese spread- approximately 8% higher in moisture content than processed cheese (cheese whiz)
  19. Function of ice cream ingredients
  20. Milk solids- protein contributes to body and smoothness
  21. Sweeteners- flavor, corn syrup reduces ice crystals
  22. Egg- delicate flavor, increases viscosity and improves body, increases whipping ability
  23. Cream- give richness, smooth texture, reduces ice crystals
  1. Factors interfering with ice crystal aggregation in ice cream
  2. Protein- gelatin, egg whites, milk powder
  3. Fat- chocolate
  4. Corn syrup
  5. Fat free- increase sugar
  6. Low fat, low sugar- increase egg white and gelatin