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43 Cards in this Set
- Front
- Back
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Know the effect of acid and base on nutrition and the color pigment in plant foods |
chlorophyll acid-brown color base- bright green amthocyanin acid- red to pink base- violet to blue xanthacanthins- tannins-whiter base acid- whiter base- more yellow |
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How does akali affect the texture of plants and why? |
makes them mushy; breaks down the hemicellulose |
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gums Where do they come from? what do we use them for? how are they classified in the fibers? |
- microorganisms, seeds, plant exudates, seaweed extract -thickening agent, to replace fat and oil when in cake- increase shelf life and volume when in ice cream- help decrease crystal size -soluble |
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What needs to be present for enzymatic browning to take place? |
oxygen, substrate, enzymes (peroxidases, phenolases, glycosidases) |
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how to prevent enzymatic browning? |
salt, sugar, acid (lemon juice), or blanching to stop enzymatic production |
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How should fruits and vegetables be stored? |
room temp- onion, garlic, potato, banana everything else in the fridge |
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hydrolytic rancidity |
lipolysis (hydrolysis) of lipids to free fatty acids and glycerol. often catalyzed by lipases |
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oxidative rancidity |
development of flavors and odors in a fat as a result of an uptake of oxygen and the formation of peroxidases hydroperoxidases and nemerous other compounds |
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the 3 phases for pectin substances |
protopectin- NOT good for jelling, goes through demethylization to become... pectinic acid- good for jelling pectic acid- NOT good for jelling |
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melting points, smoke points, and shortening capability |
sat. fat- monounsat.- polyunsat.- Lowest smoking point Shortening- fat surrounds gluten so you dont get an elastic effect |
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How do fats act as tenderizers? |
by shortening- coats the protein molecules making it difficult for them to combine and create that stretchy material called gluten |
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Whats the stabilizer in whipped cream foam? |
Chilled fat...has to be cold |
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the 4 different types of crystals in fat? |
Alpha- very fine, unstable, quickly melt and reform into beta crystals Beta-prime- very fine, reasonably stable, smooth surfaces, most desirable to use intermediate- grainy, not recommended, because of too warm of temp so it changes back and forth between liquid and solid Beta- extremely stable, coarse, undesirable fat crystals, recrystallizes without being disturbed |
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Fat: Acrolein |
a highly irritating and volatile aldehyde formed when glycerol is heated for to the point which two molecules of water split from it. |
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Winterizing Oil |
a refining technique in which oil are chiled carefully to precipitate and remove fractions with high melting points that would interfere with flow properties. Ex: salad dressing |
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Hydrogenation |
addition of a hydrogen to an unsaturated fatty acid n the presence of a catalyst to decrease unsaturation of the molecule and raise the melting point |
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trans fat |
elevates levels of LDL higher in a stick than a tub |
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Proteins Isoelectric point |
The pH at which a protein molecule has lost its electrical charge and is most susceptible to denaturation and precipitation |
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isoelectric features |
proteins minimal solubility |
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Ways to denature protein? |
heat, agitation, acid tertiary--> secondary |
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Levels of PRO structure |
1. primary- covalently bonded back-bone chain of protein CCNCCNCCN 2. Secondary- alpha helix configuration of the backbone of many proteinsheld by secondary bonding forces notably by hydrogen bonds also may be in otherforms ex. B pleated sheet 3. Tertiary structure- Distorted convolutions of helicalconfigurations of a protein; the form in which many proteins occur in natureand which is held by secondary bonding |
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What affect does heat have on the structure? |
When heat is applied to food containing protein it begin to denature and gradually relax from the tertiary to the secondary |
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What effects the juiciness of meat? |
water holding capacity amount of fat/ marbling |
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Know ways to tenderize meat |
meat tenderizer, moist heat cooking, mechanical tenderizing- blades and needles, pounding, cubing, meat grinder |
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how do enzymes used in meat tenderizers act on meat? |
breaking down the protein, not active at room temperature must be heated |
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which protein has the least connective tissue? |
fish |
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rigor mortis |
after- more tender, pH decreases, temperature increases |
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how does moist heat help tenderize some meats? |
if allows sufficient time for the collagen to turn into gelatin without toughening the muscle proteins |
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Why does fresh pineapple not allow gelatin to set? |
bromelian |
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how can evaporated milk be whipped into a foam |
must be cold and higher concentration of FAT and PRO |
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how is milk clotted? what is used for this? |
clotting is accomplished by adding acid and renin. used in making cheese and cream lactic-acid forming bacteria and controlled incubation generates the acid needed to foarm the clot once clumped or curdled you press out the whey |
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what fatty acid is important for the flavor of butter? |
butyric |
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Why do we put salt in the ice when freezing homemade ice cream? |
-salt lower the temperature around it |
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how do we promote small crystal development in ice cream? |
agitating- stirring |
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what is overrun? |
increase volume % that occurs when ice cream is frozen with agitation |
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Similarities between candies and frozen desserts |
-want small ice crystals -a frozen ice cream is a colloidal dispersion classified as a foam -ice crystals form the solid continuous phase - air incorporated from agitation during freezing is the discontinuous or dispersed phase |
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Milk pasteurization |
whey is destroyed during used to kill bacteria |
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Most abundant protein in eggs? |
ovalbumin |
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emulsifier in egg? |
lecithin |
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why do some hard boiled eggs have a green ring around the yolk? |
sulphur interacting with iron cooked to long, or not cooled fast enough |
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Why are eggs pasteurized ? |
to kill salmonella, heat in water bath but not too high of a temp |
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know factors that influence the stability of egg white foams |
what you add to it- cream of tartar (acid) sugar- increases stability, decreases volume salt, fat (yolk), liquid- decreases stability beating- thickens and decreases stability |
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define emulsion and explain how one works |
colloidal dispersion of liquid in another liquid. Emulsifiers stabilize it and coats the molecule so they can be next to each other without touching each other |
