Term
| Definition of food chemistry |
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Definition
| the study of the physical and chemical properties of food constituents and their interactions during processing and storage of food. |
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Term
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Definition
water
proteins
carbohydrates
lipids
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Term
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Definition
vitamins
minerals
pigments |
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Term
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Definition
phenolics
flavanoids
alkaloids
terpenols
sulfur compounds |
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Term
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Definition
non-enzymatic browning (maillard browning)
enzymatic browning
oxidation
hydrolysis
metal interactions
lipid isomerizatin
lipid polymerization |
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Term
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Definition
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Term
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Definition
structure/texture
taste/appearance
stability
spoilage
heat transfer medium |
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Term
| water and biological tissues |
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Definition
regulates body temperature
solvent for biological processes
carrier of nutrients and waste
reactant in hydrolysis
induces formation of structures
mediates enzyme activity |
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Term
| number of anomalies of water |
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Definition
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Term
| is it easy or hard to break bonds between water molecules |
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Definition
| it is difficult to break one bond, but once one is broken it is easier to break more and more (same with formation) |
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Term
| Thermal conductivity of ice VS. water |
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Definition
| Thermal conductivity of ice is 4 times greater than water |
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Term
| electrical conductivity of ice vs water |
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Definition
| electrical conductivity of ice is lower than water |
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Term
| diffusivity of water vs. ice |
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Definition
| water is 9 times more diffusive than ice |
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Term
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Definition
| The region in the neighborhood of a solute in which the ordering of the solvent molecules is modified by the solute molecule |
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Term
The positive change in delta G results from a decrease in the entropy of the system.
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Definition
| This decrease is partly due to alteration in the orientation of water molecules in the hydration shell. |
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Term
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Definition
the tendency of a molecule to escape from a solution
ie. water molecules to "escape" into water vapor |
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Term
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Definition
| water seeps in and breaks the hydrogen bonds |
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Term
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Definition
| Foods NOT rich in polymeric materials exhibit these types of isotherms |
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Term
Foods rich in polymeric materials exhibit this type of isotherm
ie. proteins, and polysaccharides |
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Definition
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Term
| No heat goes in or out of the system |
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Definition
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Term
| Importance of Aw in foods |
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Definition
- Helps to predict the Moisture content of foods
- Affects Chemical stability and shelf-life
- influences physical stability
- affects Microbial growth
- helps in designing intermediate moisture foods
- useful in designing packaging (moisture protection)
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Term
| Intermediate Moisture Food |
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Definition
where the food can be on the shelf and not go bad or have microbial growth occur.
Can get the right Aw but adjusting the pH, temperature, or adding preservatives |
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Term
Intermediate Moisture Foods
Aw range
and how to reduce Aw |
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Definition
Range: .6-.8
Add solutes (sugar, salt, etc), use microbial agents to further lower Aw so that yeast and mold don't grow |
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Term
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Definition
- Increase conc. of hydrophilic solutes that bind to water
- Decrease moisture content of foods/dehydration
- Freeze Foods (Ice/glassy water not available to react)
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Term
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Definition
Collapse of capillaries and cellular structures during desorption
Possible phase change in the material |
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Term
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Definition
| cause the release of an adsorbed substance from a surface |
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Term
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Definition
| hold molecules as a thin film on a surface |
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Term
| desorption vs. resorption |
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Definition
| If a food is more prone to phase transitions then resorption is preferable |
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Term
| Foods undergo phase changes during storage (T or F) |
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Definition
True
Water activity can change and will change which can cause phase changes during storage |
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Term
| Molecules display 3 types of motions |
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Definition
Vibrational
Rotational
Translational |
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Term
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Definition
Molecular mobility is greatly reduced
therefore diffusion-limited processes become more stable |
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Term
| As ice crystalizes out of a solution what happens to the %solute? |
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Definition
| The percent solute will go down but the temperature of the solution will stay the same unless the solution is adiabatic. If it is, the temperature will go up as the percent solute goes down |
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Term
| Why does temperature go up when ice crystalizes? |
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Definition
| Because the formation of ice releases heat |
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Term
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Definition
Where maximum solubility is
Saturated solution, crystalline solute and crystalline solvent are all in equilibrium
also the lowest melting point of ice |
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Term
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Definition
| isothermal melting causes 10^3 fold decrease in viscosity and the material becomes rubbery |
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Term
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Definition
Viscosity is decreased so much the material enters the glassy state
Free volume increases |
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Term
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Definition
| Low viscosity = fast moving molecules |
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Term
All diffusion limited processes are very slow in the glassy state
(T or F) |
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Definition
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Term
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Definition
| to make plastic or moldable |
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Term
Molecular entanglement can...
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Definition
• Slow rates of water crystallization in frozen foods.
•slow moisture migration in bakery foods/gel-type products.
•These are related to polymer behavior in an entangled network and interaction of water molecules with the network.
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