NDFS 250 exam 1

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NDFS 250 exam 1
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2012-09-29 00:07:37
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Food science
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Dr. Pikes NDFS 250 exam
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  1. What is Food Science?
    • Food Science is
    • the multidisciplinary study of food Disciplines such as chemistry, microbiology and engineering are used to study the nature of food.
  2. Food Science:  the multidisciplinary study of food
    Engineering, Chemistry, Microbiology, Law, Statistics, Nutrition, Physics, horticulture and animal science 
  3. Food Quality Parameters
    Appearance  

    Odor  

    Taste  

    Texture  

    Nutrition

    Safety
  4. Sensory Evaluation
    Discipline used to evoke, measure, analyze and interpret responses that are perceived by sight, smell, taste, touch, and hearing.
  5. Instrumental (or objective) Evaluation
    Tests that do not rely mainly on human senses.
  6. Hedonic Rating Scale
  7. Sensory Evaluation
    Attribute ideality (Just About Right or JAR)

    • Consumer panelists are asked to focus on
    • a single attribute and determine if is at an
    • appropriate level
  8. Paired Comparison:
    • Are
    • the samples the same or different?
  9. Duo-trio:
    • Select the sample that matches the reference. 
  10. Triangle
    • Select the odd/different sample
  11. Gas Chromatography
  12. Rheology
    science dealing with the deformation and flow of matter

    • Viscosity
    • resistance to flow.

    Elasticity

    Stability to recover size and shape after deformation.

    Elasticity

    • Plasticity
    • to retain a shape attained by deformation
  13. Rheology
    • TA-XT2
    • Texture Analyzer
  14. Viscometer 
    measures viscosity of fluids
  15. Consistometer
    • Consistometer measures the distance a given volume of
    • product flows during a specified time.
  16. Latent heat
    The heat needed to cause a change of state in water.  ( ice --> water 80 cal and water -->steam 540 cal.)

    No change in temperature
  17. True Solution
    •Ions or small molecules

    • •< 1nm in diameter
    • •Very stable

    •Transparent

    • •Usually can not form
    • gels
  18. •Colloidal Dispersions
    •Macromolecules or small groups of molecules

    •Usually 1-100 nm in diameter

    • •Visible under electron
    • microscope

    •Moderately stable

    •Translucent or opaque

    •Form gels
  19. •Suspensions
    •Large groups of molecules

    •> 100 nm

    • •Visible under light
    • microscope

    • •Do not pass through
    • filters

    • •Unstable; i.e., settle
    • out

    •Opaque

    •Can not form gels
  20. Sol
    Dispersed phase solid

    continuous phase liquid
  21. Emulsion
    • Dispersed phase liquid
    • continuous phase liquid
  22. Foam
    • Dispersed phase gas
    • continuous phase liquid
  23. solid foam
    • Dispersed phase gas
    • continuous phase solid
  24. Gel ( solid emulsion
    • Dispersed phase liquid
    • continuous phase solid
  25. Hard water
    calcium and magnesium ions
  26. Hydrogen bonding of water molecules
  27. Sensible heat
    Change in temperature produced by heat

    Can be measured with a thermometer
  28. Endothermic
    Absorbs heat.

    Example: Melting ice
  29. Exothermic
    Releases heat.

    Example: Freezing water
  30. •Molal solution
    •Concentration (moles) of solute per kg of solvent
  31. •Molar solution
    •Concentration (moles) of solute per liter of solution
  32. Colligative properties
    • Properties that depend upon the number of molecules
    • present, not upon their nature or size.

    • Examples:
    •    Vapor pressure
    •    Boiling point
    • Freezing point
    • Osmotic pressure
  33. For every mol of nonvolatile solute in 1 kg of solvent
    Boiling point of that solution is raised 0.52 ºC

    Freezing point is lowered 1.86 ºC
  34. elevation in bp
    elevation/960
  35. Water Activity (aw)


    • One means of determining microbial
    • stability of food

    • Related to the rate of some
    • chemical reactions in food, e.g., vitamin loss, lipid oxidation, browning
  36. Glassy state
    • State in which amorphous material is so viscous that it does not flow under its own
    • weight and molecules are practically immobile

    Physically hard, brittle and able to shatter…like a glass window
  37. Temperature of glass transition (Tg)
    The temperature at which a substance changes from a rubbery state to a glassy state (or vice versa)

    Related to stability of some foods, especially dry foods and frozen foods.
  38. How emulsifiers work 
    The non-polar tail is attracted to the oil (discontinuous phase) and the polar head is attracted to the water (continuous phase).
  39. D-Glucose
  40. Anomeric carbon
    • The carbon which becomes assymetric when the open-chain structure closes to form the ring structure
  41. Fructose
  42. Galactose
  43. Sucrose
  44. Maltose
  45. Lactose
  46. Invert sugar
    Equimolar mixture of D-glucose and D-fructose   formed by hydrolysis of sucrose
  47. Formation of invert sugar
    It is the product when acid is added to a sucrose ans water mixture and heated
  48. Invert sugar
    it can be commercially produced without bees

    The term "invert" refers to change in sign + to - on the degrees of rotation of plane polarized light.
  49. invert sugar application 
    Invert sugar has a lower water activity than that of sucrose, so it provides more powerful preserving qualities (a longer shelf life) to products that use it.
  50. Reducing sugar
    • A carbohydrate that can reduce Fehlings
    • Reagent or Benedicts Reagent

    • Most simple sugars are reducing
    • sugars, except sucrose
  51. Reducing sugar significance
    maillard browning - typically a reaction between a reducing sugar and an amino group
  52. relative sweetness/solubility
    F,S,G,M,G,L
  53. Amylose
  54. Amylopectin
  55. Cellulose
  56. Pectin
  57. Fiber
    Carbohydrates (and lignin) that cannot be broken down by human digestive enzymes
  58. Vegetable gums
    Complex polysaccharides that typically impart high viscosity at low concentrations.
  59. Vegetables
    • Food uses of vegetable gums
    • Inhibit crystallization

    Whipping aid

    Foam and emulsion stabilizer

    Adhesive and binding agent

    Coating agent

    Prevent gel breakdown (syneresis)

    Suspend solids

    Flavor carrier

    Fat replacer
  60. Tests for candy doneness  Boiling point 
    Measures concentration of solutes in the syrup. 

    Advantage: objective

    Disadvantage: must take into account the presence of other substances and altitude
  61. Cold water test
    Measures consistency of the syrup

    Advantage: takes into account all variables

    Presence of substances other than sucrose

    Altitude, barometric pressure

    Disadvantage:  subjective
  62. Crystalline Confections
    Substance in which molecules fit together into a regular  geometric arrangement (crystal lattice).
  63. Amorphous Confections
    Substance in which molecules have aggregated in a random, disordered fashion.
  64. Steps in Making Crystalline Candy
    • Darn Boys Came Cause Kiss
    • 1.Dissolve sucrose in water, then
    • heat  (Solution is unsaturated)

    • 2.   Boil  (112 -115°C) away excess water  (Inversion occurs; solution is near
    • saturation)

    • 3.  Cool
    • to 40ºC (it becomes supersaturated)

    • 4.  Crystallize
    • by continuous, rapid beating until kneadable

    5.   Knead  (it becomes less glossy and lighter in color)
  65. Steps in Making Chewy Amorphous (Non-Crystalline) Candy
    • 1. Combine
    • corn syrup,  sugar and water, and heat to
    • 118ºC.

    2.  Add evaporated milk slowly.

    • uInterfering
    • compounds prevent crystallization
  66. Non-enzymatic Browning
    • 1.Caramelization   (CHO  +  dry
    • heat --> Ascorbic acid

    • 2.
    • Maillard Reaction  C=O + NH2 -->Ascorbic acid
  67. Frozen custard 
    (or French ice cream)

    Contains eggs
  68. Mellorine
    Animal or vegetable fat
  69. (don't forget Sherbet)

    Water ice (or sorbet)
    No dairy ingredients
  70. Ice Cream making 
    • Brain power helps pasteurization so serve
    • and help
  71. Ice cream ingridients Emulsifier/Milk Fat
    Emulsifier/milk fat - (suspension, if homogenized-colloidal)
  72.  Ice cream ingriedients  Stabilizer
    Collodial
  73. Air bubble 
    Foam
  74. Ice cream ingriedients Milk Protein
    collodial
  75. Ice cream ingriedients Sugar and salt
    true solution
  76. Ice Cream Ingridients - Ice
    colloidal or suspension
  77. Overrun
    • Overrun (%): a measure of the
    • amount of air incorporated (by volume or by weight)
  78. Overrun equation
  79. Reducing sugar
    Browning

    Thering opens up the aldehyde is available and it will react

    React=browning 
  80. Ice Cream aging
    • Cooling the ice cream mix a minimum of four hours
    • Mix becomes more viscous and whipping quality improves
  81. Factors affecting ice crystal formation
    Ingredients

    • Agitation
    • Freezing rate - The faster the freezing rate, the
    • greater the number and the smaller the size of ice crystals

    Temperature fluctuations
  82. Carboxylic acid
  83. Ascorbic Acid
  84. Carbonic
  85. Lactic Acid
  86. Phosphoric Acid
  87. Weak acids
    Have at least one H+ that does not completely ionize

    Examples:  most food acids
  88. Strong acids
    Have at least one H+ that completely ionizes

    Examples:  hydrochloric, nitric, phosphoric, sulfuric
  89. Active acidity (pH)
    measure of Ionized or free H+ at a given time

    • Measured electronically (pH meter) or by color change (e.g.,
    • litmus paper)
  90. Total acidity (titratable acidity)
    Measures both ionized H+ and nonionized H+; total H+ available for donation in free and bound state

    Measured by titration with a base, e.g., NaOH to colorimetric endpoint
  91. Buffer Base
  92. Buffer Acid
  93. Fruit classification
  94. Simple fruit
    Developed from one ovary in one flower
  95. Pomes
    • simple fruit containing a core plus seeds
    • Apple, Pear
  96. Drupes
    • simple fruit containing a stone or pit
    • enclosing a seed

    • Cherry
    • Plum
    • Peach
  97. Aggregate fruit
    Fleshy fruit developed from several ovaries in one flower

    Raspberries    Strawberries    Blackberries
  98. Multiple fruit (Composite Fruit)
    Developed from a cluster of several flowers

    Pineapple      Figs
  99. Cell Wall
    Contains cellulose, hemicellulose, lignin and pectic substances
  100. Vacuoles
    • Contains water soluble compounds,
    • including water soluble pigments
  101. Cytoplasm 
    • The protoplasm of a cell, excluding
    • the nucleus

    • Contains plastids, mitochondria,
    • and water soluble compounds, e.g., salts, sugars
  102. Plastids
    uDifferent types contain fat soluble pigments (chloroplasts, chromoplasts), starch (amyloplasts) and oils (elioplasts) 
  103. Middle lamella
    • A thin layer of viscous
    • intercellular material that “cements” cells together

    • Composed of pectic
    • substances, calcium, cellulose, and other polymers
  104. Cellulose
    Primary structural component in cell walls of plants.  Linear polymers of glucose with thousands of subunits. Does not soften when heated, even in acid.
  105. Hemicellulose
    Branched polymers of xylose and glucose with minor amounts of other compounds

    Softens when heated in acidic or basic solution
  106. Pectin
    Polymers of galacturonic acid and its esters

    Binds with hemicellulose and cellulose to form a fibrous network for structural support of plant tissues

    Softens during ripening and on heating
  107. Pectic substances
    Protopectin    to        pectin  to        pectic acid
  108. Lignin
    Polymers containing benzene derivatives

    Does not soften even when heated; contributes woody characteristics to plants

    Woody, fibrous material in mature broccoli and asparagus stems is lignin
  109. fruit ripening 
    Color:  chlorophyll decreases, other pigments predominate

    Texture:  softens

    Acidity:  decreases , pH goes up slightly

    Pectic substances:  remain constant – pectin decreases and pectic acid increases

    Flavor/Aroma:  flavor volatiles increase

    Form of carbohydrate: starch decreases and sugars increase
  110. Enzymatic browning
    Polyphenols + O2 -phenolase> Quinones -polymerization> Brown pigments
  111. Prevention of enzymatic browning
    Avoid oxygen

    Add salt

    Keep product cool

    Alter pH


    Blanch


    Add reducing agent
  112. Vegetable Classification
    Leafy
    • lettuce, cabbage, brussel
    • sprouts, chard, kale
  113. Vegetable Classification
    Seeds
    peas, beans, corn
  114. Roots
    carrots, rutabaga, sweet potato
  115. Tubers 
    Short thickened fleshy part of an underground stem
  116. Bulbs
    onion, garlic, leek
  117. Flowers
    • broccoli, cauliflower, globe
    • artichoke
  118. Fruit
    cucumber, okra, tomato, squash, egg plant, green beans, zucchini
  119. Stem or shoot
    asparagus, celery
  120. Compartmentation
    • formation of garlic odor
    • onion tears
  121. Vegetable
    cooking methods
  122. Baking soda decreases cooking time
    Limit to 1/8 teaspoon/cup of legume

    Too much soda causes dark color, mushy texture and increases thiamin loss
  123. Carotenes plant pigment
    tomatoes, watermelon
  124. Flavonoids plant pigments
    berries
  125. Betalains

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