Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
105 Cards in this Set
- Front
- Back
|
Water can be used in...
|
-beverages
-processing -harvesting -heating/cooling |
|
|
Water Structure
|
-H2O
-polar -forms hydrogen bonds |
|
|
Free Water
|
-bulk water
-solvent water |
|
|
Bound Water
|
-no removable
-hindered mobility -first water molecules to ineract with functional groups of solutes |
|
|
Water Activity
|
-measure of vapor pressure of water molecules in the space above a food in a closed container
-indicates the degree of available water |
|
|
aldose
|
aldehyde group
|
|
|
Ketose
|
Ketone group
|
|
|
Pentose
|
five carbons
|
|
|
Hexose
|
six carbons
|
|
|
Carbohydrates in Water
|
-very soluble in water
-form hydrogen bonds with water -polar |
|
|
Functional Groups in Carbs
|
-hydroxyls
-aldehydes -amines -acids -Phosphates |
|
|
Simplest Carbohydrate
|
Glucose
|
|
|
Reducing Sugars
|
sugars that contain a free aldehyde or ketone
|
|
|
Aw of ideal pure water
|
1
|
|
|
Aw of ideal food with no water
|
0
|
|
|
Water Activity equation
|
Aw= P/P0
p-paretial vapor pressure of water p0- vapor pressure |
|
|
Water Sorption Isotherms
|
tell the amount of water absorbed onto a component
|
|
|
Desorption isotherm
|
start with a smaple that is very wet and see how much moisture is lost
|
|
|
sorption Hysteresis
|
discrepancis between the adsorption and desorption data
|
|
|
Aw values can be controleld by...
|
types of salt
ex. hotdog experiment |
|
|
Moisture Migration
|
mixing ingedients with different moisture contents will cause moisture migration
|
|
|
Moisture Migration is driven by...
|
Aw potential not moisture content
|
|
|
Humectants
|
solutes that have a higher affinity to absorb water
-helps maintain soft texture at low Aw |
|
|
Ways to lower water activity
|
-add solutes like sodium chloride or sugars
-dehydration |
|
|
intermediate Moisture foods (IMF)
|
created by addition of solutes to lower water activity
|
|
|
Tg
|
temperature range at which amorphous or non crystalline solid changes from hard and brittle to soft and rubbery
|
|
|
Maillard browning reaction
|
-non oxidative browning
-consists of amino acid and a reducing sugar -aromas and flavors are formed -leads to undesirable brown color or to desirable colre (ex. bread crust) |
|
|
Lipid oxidation can lead to:
|
-off-flavors
-changes in color or texture -reduced shelf-life -impairment of nutritional quality |
|
|
Enzymatic Reactions
|
-water acts on the structure of the enzyme and substrate
-water may interrupt hydrogen bonding and change protein structure -water facilitates diffusion of substrates and catalysts for reaction -water may become a part of reaction (ex. hydrolysis) |
|
|
Most abundant Carbohydrate
|
cellulose
|
|
|
Sweeteners
|
-sucrose, fructose, glucose
-sugar alcohols also used to reduce calories |
|
|
Naturals gums
|
-water soluble polysaccharides
-extracted from land or marine plants -contributes viscosity or gelling ability |
|
|
Guar Gum
|
-endosperm polysaccharide of Cyamopsis tetragonolobus
-grown in india -hydrates to rapidly produce highly viscous solutions -viscosity no affected by changes in pH |
|
|
Locust Bean Gum
|
-derived from the seed of the carob tree, Ceratonia siliqua
-grows near Mediterranean -provides body, smoothness, and chewiness |
|
|
Gum Arabic/Acacia
|
-produced as teardrop shaped from the bark of Acacia trees
-dissolves in water -low viscosity solutions -decreases sugar crystallization in candies -aids in formation and maintenance of small ice crystals in frozen desserts |
|
|
Gum Tragacanth
|
-collected from bushy shrubs in Iran, Syria, and Turkey
-occurs in bark wounds -found in salad dressings and sauces -excellent stability in heat and acidic conditions |
|
|
Agar
|
-bacteriological culture medium
-obtained from red marine algae in Japan -remains stable at temps above the initial gelation point -reduces syneresis -provides desirable texture in frozen desserts -provides stability in cheeses -retards staling in baked goods |
|
|
Carrageenan
|
-extracted from seaweed
-when cation is K+ a firm gel is produced -when cation is Na+ the polymer is cold water soluble and non-gelling -stable above pH 7 -degrades rapidly below pH 5 -added to chocolate milk to reduce chocolate particle precipitationg by forming weak get with milk protein |
|
|
Alginates
|
-extracted from brown algae
-forms gels at room temp in presence of Ca++ ions -provides body, texture, and resistance to ice crystals in frozen desserts -used in French salad dressing for thickening and emulsion |
|
|
Dextrans
|
-product of microbial biosynthesis
-increases moisture retention in candies -inhibits sugar crystallizaation and crystal growht -gelling agent in gum and jelly candies -water crystallization inhibitor -cant be used in foods in US or Europe |
|
|
Xanthan Gum
|
-cellulose chain with oligosaccharide groups
-soluble in hot or cold water -produces highly viscous solutions at low concentration -thermally stable -acidity have little effect on viscosity -used in beverages to enhance mouth feel and flavor release |
|
|
Gellan
|
-produced under aerobic condition
-requires Na+, K+, Ca++, or Mg++ to form a gel -useful where high gel strength is required |
|
|
Carbohydrates
|
-major engery source for animals
-help provide structure -fewer calories than lipids -sweeteners -provides texture -thickeners -dietary fibers -carbon sources |
|
|
Most important ketose
|
fructose
|
|
|
Sucrose formation
|
condensation reaction between glucose and fructose
|
|
|
Most abundant Carbohydrate
|
D-glucose
|
|
|
Monosaccharides
|
-smallest sugars
-building units of other carbs -3-9 carbons |
|
|
d-sugars
|
-sugar has -OH group on the right hand side
-most sugars in nature are D sugars |
|
|
L-sugars
|
sugar has first -OH group on left hand side
|
|
|
Aldose
|
-sugar containing an aldehyde
-ex. glucose, galactose, mannose |
|
|
Ketose
|
sugar containing a ketone
|
|
|
glucose isomerase
|
enzyme which helps catalyze the reaction that converts glucose to fructose
|
|
|
Epimers
|
differ in one configuration of a single asymmetric center
|
|
|
Hemiacetal
|
ring structure formed throug ha rxn between the aldehyde group and an -OH of the sugar
|
|
|
Hemiketal
|
ring sturcture fromed thorugh a rxn between the ketone group and an -OH of the sugar
|
|
|
five member rings
|
kinetically favored
|
|
|
six member rings
|
thermodynamically favored
|
|
|
glycaric Acids
|
sugars with 2 carboxyl groups (one on each end of sugar)
|
|
|
Oligosaccharides
|
-condensation products of monosaccharids
-monosaccharides units connected by glucosidic linkages -contain 2-10 sugar units -ex. Disaccharides |
|
|
Disaccharides
|
-smallestt oligosaccharide
-2 monosaccharide units -ex. sucrose (glucose and Fructose) -maltose (2 glucose units) |
|
|
Trisaccharides
|
oligosaccharides containing three sugar units
-ex. maltotirose (3 glucose units) |
|
|
Cyclodextrins
|
-cyclic nonreductin D-glucopyranosyl oligomers
-consist of 6,7, and 8 glucose units |
|
|
Reducting sugars
|
-any sugar having an aldehyde or ketone group that id readily converted into a carboxylic group by Cu or Ag
-rxns can easily be detected by color changes -ex. glucose, fructose, maltose, lactose |
|
|
Polysaccharides
|
-consist of more than 10 sugar units
|
|
|
Homo-polysaccharide
|
-glycan composed of a single monosaccharide unit with one or more types of glycosidic linkages
-ex. starch, glycogen, cellulose |
|
|
Hetero-polysaccharide
|
-glycans compose of more than one type of monosaccharide
-ex. gums, dietray fibers, pectinic substances |
|
|
Starch
|
-second largest biomass
-hundred of glucose units -major form of energy in plants |
|
|
Starch is stored in...
|
seeds, roots, fruits ,and leaves
|
|
|
Starch consist of...
|
amylose and amylopectine
|
|
|
amylose
|
-linear molecule containing tons of glucsoe units
-alpha 1-4 linkages |
|
|
Amylopectin
|
-highly branched
-alpha 1-6 linkages -cluster structure -phosphate derivative |
|
|
Starch Categories
|
-waxy
-normal -high-amylose |
|
|
Starch granules
|
-Maltese cross
-center of cross is know as hilum, organic center -once gelatinization takes place the maltese cross disappears -insoluble in cold water -absorb cold water and sweel -absorb hot water, swell, rupture, collapse, form a paste |
|
|
Cellulose
|
-present in vegetables and fruit
-cannot be digested by humans -glcose units with beta 1-4 linkages -gives tough texture to foods -linear structure prompts crystallization |
|
|
Gums
|
-provide thickening and stabilizing effects to food
-isolated from plant seeds, plant exudates, sea wees, microorganisms |
|
|
Pectin Substance
|
-can form two types of gels
-High DE pectin and Low Methoxy Pectins |
|
|
High DE Pectins
|
form gels at acidic pH and in the presence of a high concentration of sucrose
|
|
|
Low methoxyl Pectins
|
-require divalent cations
-can be fromed without sugar and over a wide pH range -gels are brittle and less elastic |
|
|
Hemicelluloses
|
-group of polymers found in cell wall of plants
-good water binging capacity -not starch or cellulose |
|
|
Pentoses
|
have five carbons
|
|
|
Hexoses
|
have six carbons
|
|
|
Carbohydrate in water
|
-very soluble in water
-form hydrogen bonds with water -polar |
|
|
complete oxidation of sugars leads to...
|
CO2 and water
|
|
|
Color Reactions
|
-acids and formation of furfural and 5-hydroxymethylfurfural products will react with phenols or amines to form colored compounds
|
|
|
Sugar Derivatives
|
-amino sugars
-deoxy sugars -sugar acids -sugar alcohols -acetylated or methylated sugar |
|
|
Fructooligosaccharides (FOSs)
|
-oligomers of sucrose with additonal fructose glucosidic linkage to fructose part of sucrose
|
|
|
Food Gums
|
-stabilize
-emulsify -suspend -foam -gel -bind -form films -viscosity -texturize |
|
|
Commercial uses of gum
|
-thermal gelation of methylcellulose
-edible film production -suspension of particles in liquid -structural foams -binding in veggie patties |
|
|
Glycogen
|
animal storage
|
|
|
Waxy Starches
|
long bodied, stringy
|
|
|
Non-waxy Starches
|
short bodied, clean cuts
|
|
|
Starch Forms
|
-A and B forms
-A form is most common -dffer in physical properties |
|
|
Starch gelatinization
|
-granule swelling
-loss of birefringence and crystallinity -leaching of amylose -endothermic -glass transiton to rubbery state |
|
|
Gelatinization
|
-collapse of molecular order within the starch granule
-point of initial gelatinization and range over which it occurs is governed by starch concentration |
|
|
Pasting
|
-dissolution of starch
-granular swelling -exudation of molecular components from granule |
|
|
Retrogradation
|
-process when molecules begin to reassociate in an ordered structure
-crystalline order appears -starch becomes less soluble -transition from amorphous to crstalline state |
|
|
Amylose and Retrogradation
|
-amylose associates parallel to one another
-affinity for water is decreased -size increase -precipitate forms |
|
|
Modified Starches
|
-crosslinking of chains
-depolymerization -pre gelatinization -addition of functional groups |
|
|
Unmodified Starches
|
clear cohesive pastes
|
|
|
Crosslinked Starch
|
-distarch phosphate esters
-decrease rate and degree of granule swelling -more stable in high temps and low pH -mroe viscous |
|
|
Phosphate ester
|
-monoester phosphate and diester phosphate modified starch
-decrease gelatinization temp -increase clarity -stabilizes against retrogradation -increases freeze-thaw stability |
|
|
Alkenyl Succinate Esters
|
-hydrocarbon chain
-emulsion stabilizers |
|
|
Hydroxyproply starch
|
-decrease gelatinization temp
-clear paste -do no retrograde -thicken |
|
|
Dietary Fiber
|
-resistant to mammalian digestive enzymes
-chemically defined by solubility |
|
|
Categories of Dietary Fiber
|
-structural polysaccharides
-structural non polysaccharides -non structural polysaccharides |
