CARBOHYDRATES
SUGARS, STARCHES, PECTINS,
AND OTHER CARBOHYDRATES
CHARACTERISTICS
 Organic compounds
 Carbon, Hydrogen, Oxygen
 Simple or complex
 Source of energy or fiber
 Important food CHOs - Sugars, dextrins,
starches, celluloses, hemicellulose, pectins,
gums
FUNCTIONS
 SWEETENERS
 THICKENERS
 STABILIZERS
 GELLING AGENTS
 FAT REPLACERS
MONOSACCHARIDES
 SIMPLE SUGARS
 MOST COMMON - 5 OR 6 CARBON
GLUCOSE
 Dextrose
 Naturally present in fruit
 Basic unit for starches
 Less sweet than fructose
 Used in food industry because of water
holding properties and ability to control
crystals
 Food for yeast
FRUCTOSE
 Levulose
 Part of sucrose
 Sweetest of all sugars
 In many fruits
 Very soluble
 Not easily crystallized
 Glucose isomerase to change glucose to
fructose
GALACTOSE
 Part of lactose – milk sugar
 Basic unit of pectic substances
 Building block of many vegetable gums
COMMON MONOSACCHARIDES
DISACCHARIDES
 Two monosaccharides
 Glycosidic bonds-readily hydrolyzed by
heat, acid, enzymes
SUCROSE
 Table sugar
 From sugar cane or sugar beet
 Glucose + fructose
 Invert sugar important in controlling
crystallization
 Most common disaccharide
MALTOSE
 Glucose + glucose
 Product of starch breakdown
 Corn syrup
 Flavoring and coloring agent in beer,
candies, shakes
LACTOSE
 Glucose + galactose
 Milk sugar
 Extracted from solutions of whey
 Not broken down or fermented by yeast
 Does not react in batter leavened with
baking soda or baking powder
 Available for Maillard reaction so added
to bakery products for browning
DISACCHARIDES
PROPERTIES OF
SUGAR
SOLUBILITY
 Solution in foods
 Varying degrees of solubility for
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monosaccharides and disaccahrides
As temperature increases  greater the
amount of sugar that dissolves
Slow heating increases the solubility
As concentration increases  boiling point
increases
Each gram molecular weight of sucrose
increases boiling point 0.940F (0.520C)
Can use temperature to determine sucrose
concentration
SATURATION
 Unsaturated – small amount of sugar in
water, can hold more sugar
 Saturated – no more sugar can be
dissolved
 Supersaturated – holds more than what
is usually soluble at a certain
temperature
 Supersaturation – heat to high
temperature and cool slowly
CRYSTALLIZATION
 Cool supersaturated solution
 Formation of closely packed molecules from the
solidification of dispersed elements in a precise
orderly structure
 Arranged around a nuclei
 Size of crystal depends on rate of formation of
nuclei and rate of growth
 Crystals form too soon  only a few  crystals
too large, continue to grow, candy grainy
MELTING POINT/HEAT
DECOMPOSITION
 Apply dry heat  sugars melt to liquid
state
 Sucrose melts and forms liquid that turns
brown
 Carmelization – nonenzymatic browning,
flavors food
 Noncrystalline
HYGROSCOPICITY
 Ability to absorb moisture
 Responsible for lumpiness (sugar)
 Decreases staling in bread
 Gives stickiness for high moisture
characteristics to foods
 Fructose most hygroscopic
INVERT SUGAR
 Acid hydrolysis of disaccharide sucrose
 Heat increases hydrolysis
 Glucose and fructose in equal amounts
(equimolar)
 Resists cyrstallization and retains
moisture
 Add cream of tartar, vinegar, molasses
(acids)
 Enzyme hydrolysis with invertase
TYPES OF SUGARS
CRYSTALLINE AND NONCRYSTALLINE
GRANULATED SUGAR
 Crystalline – table sugar
 Sugar cane or sugar beet
 Affects texture of baked goods
 Improves body and texture of ice cream
 Fermented by yeast
 Retards growth of microorganisms
 Raw sugar banned by FDA
 Turbinado –raw sugar separated in centrifuge,
washed with steam
 Retailed as fine or extra fine
POWDERED SUGAR
 Pulverized granulated sugar
 Add cornstarch to prevent caking
 X designates fineness
BROWN SUGARS
 From cane sugar – late stages of refining
 Crystals of sugar coated with molasses
 Contains invert sugar
 Sold in grades
 More refined  lighter color, less flavor,
lower grade – for baking – less flavor
 Higher, darker grades more flavorful and
suitable for cooking strong flavored
foods
CORN SYRUP
 Acid and high temperatures to hydrolyze
corn starch
 Varying degrees of sugars
 High fructose corn syrup (HFCS) from
high glucose corn syrup – use enzyme
glucose isomerase
 Significant use in food industry
MOLASSES AND SORGHUM
 By-product of sugar production from
sugar cane
 Mineral content varies
 Bitterness increases as refinement
continues – blackstrap molasses
 Treacle – dark fluid left after sugar cane
is processed
 Sorghum – from cane sorghum, similar
to molasses
MAPLE SYRUP AND HONEY
 Maple syrup from sap of mature maple
trees
 Water evaporated, organic acids cause
flavor
 Honey flavors according to flower
nectars
 USDA has standards for grades of honey
ALTERNATIVE
SWEETENERS
 Non-nutritive – high intensity sweeteners
 Approved saccharin, aspartame,
acesulfame-K, sucralose, neotame
 Except for sucralose not enough bulk to
substitute in recipes
 Cyclamates – banned
 Sugar alcohols - polyols– improve bulk,
mouthfeel, and texture
SUGAR COOKERY
CANDIES
CRYSTALLINE CANDIES
 Generally soft
 Smooth, creamy with tiny crystals that
cannot be detected with the tongue
 Fondant and fudge
 Use interfering agent to prevent early
crystallization
 Must concentrate solution-test
temperature to determine concentration
 Complete solution of crystalline sugar
INTERFERING AGENT
 Interfere with size or rate of crystal
growth
 Contribute to viscosity of syrup and
elevate the boiling point
 Examples – milk, butter, cream, eggs,
chocolate, cocoa, proteins, fats, dextrins,
invert sugar, corn syrup
NON-CRYSTALLINE
CANDIES
 Amorphous
 No definite crystalline pattern
 Cook to very high temperature
 Adding large amounts of interfering agent
 Combination of methods
 Hard – brittles, high temperature, low moisture
 Chewy – caramels, high interfering agent
 Aerated – marshmallows, air trapped in protein
foams and interfering agent
POLYSACCHARIDES
 Complex carbohydrate polymers
 Properties depend on sugar units,
glycosidic linkage and degree of
branching
 Starches, Pectins, Gums most important
 Hydrocolloids – water loving colloidal
substances
STARCH
 Plant polysaccharide - linked glucose monomers
 GRANULES - formed in cells, grow by adding on
layers
 Long-chain glucose polymers
 Insoluble in water
 Form temporary suspension
SOURCES
 Characteristic of finished food depends on
starch source
 Seeds, roots and tubers
 Cereal grains - wheat, corn, rice, oats
 Roots and tubers - potatoes, arrowroot,
cassava
STRUCTURE
AMYLOSE AND AMYLOPECTIN
AMYLOSE
 Straight chain or linear fraction
 1/4 of all starch
 Thousands of glucose units
 Forms thick gels-hold shape when
molded, rigid
AMYLOPECTIN
 Highly branched
 3/4 of starches
 Thickens but does not gel
 Proportion of amylose:amylopectin
influences cooking qualities and keeping
characteristics of finished food product
AMYLOPECTIN
STARCH CHARACTERISTICS
 Ability to absorb water limited
 In uncooked stage is insoluble in cold water - forms
temporary suspension because polymer is too large
 Doesn’t change boiling point or freezing point of liquid
 Reversible
EFFECTS OF HEAT
DRY HEAT
 Heating - increases uptake of water
 Dextrinization
 Color and flavor changes
 Reduced thickening power
 Nonenzymatic browning
 Dry flour browned
MOIST HEAT
 Complete absorption as heat increases -
permanent swelling, irreversible
 Sol - as starch continues to come out of
granules
 Viscosity-thickness, thinness of liquid
 Translucency increases during heating
GELATINIZATION
 Sum of changes in first stages of moist
heating of starch granules
 Gelatinized granules = opaque, fragile,
ordered structure disrupted
 Temperature of gelatinization differs for each
starch
 Short chains of amylose come out of the
granules
 Irreversible changes
CONTINUED HEATING
 Gelatinization requires addition of heat
 Cooking develops flavor
 Pasting occurs
 Granules swell
 Granules of starch swell independently
PASTE CHARACTERISTICS
 Concentration of starch affects
consistency
 Clear thickened gel made from root
starches or waxy versions of starches
 Cloudy gels from cereal starches
FACTORS AFFECTING
GELATINIZATION
ACID
 Fragments (hydrolyzes) starch molecule
= thinner hot paste and less firm product
 Hydrolysis = less hydration of starch
 Add acid after gelatinization and after
starch has cooked
 Applicable - lemon juice, vinegar,
tomatoes
AGITATION
 Over-stirring causes granules to burst,
empty bound water = gel will thin
 Creates more uniform mixture
OTHER FACTORS
 FAT AND PROTEIN- coats (adsorbs) to surface of
granule = delays hydration
Fat in pie crust to prevent clumping
 SUGAR - competes for liquid = delays absorption by
granule = thinner mixture
Elevates temperature for gelatinization
 ENZYMES - hydrolyze starch molecules
TIME AND TEMPERATURE
 Lengthen heating time = causes
granules to rupture - thins product
 More rapid heating = smoother paste
 Bring to boil over direct heat
GELATION
 Formation of a gel when gelatinized starch is cooled
 Strong amylose bonds
 Elastic solid
 Retrogradation-reverting to crystalline state
 Syneresis - water loss during retrogradation,
“weeping”-as water evaporates dried out rubbery
matrix of starch
 Non-pourable, highly viscous
SEPARATING AGENTS
 DEFINED - ingredients or additives which physically
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separate starch granules during hydration, allowing
maximum hydration
Prevents lump formation
FAT -ROUX- forms film around granule = each granule
swells independently of others
COLD WATER- SLURRY-physically separates granules
(hot water causes partial gelatinization)
SUGAR-LIAISON - physically separates
MODIFIED STARCHES
 Defined-starches which have been
chemically altered to produce physical
changes
 Will improve stability, convenience,
performance during food processing
 Use acids or oxidizing agents
 FDA-regulations governing modification
EXAMPLES
 PREGELATINIZED STARCH - gelatinized, dried, can
reconstitute without heat (instant potatoes, hot
cereal)
 Acid-modified starch - treated with acid slurry, forms
strong gel upon cooling
 Cross-linked starches - acid resistant, resists rupture
 Cold water-swelling - instant starch that remains
intact
FUNCTIONS OF MODIFIED
STARCHES
 Increase acceptability of product flavor
and consistency
 Prevent retrogradation
 Stabilizers in conjunction with emulsifiers
 Improve freeze-thaw stability
 Prolong shelf life of frozen food by
preventing oxidation
WAXY STARCHES
 Commonly used in pie fillings
 Made from natural starches
 Practically no amlyose
 Thicken at lower temperature but no
gelling
 Less retrogradation
 Barley, corn, rice, sorghum
HIGH AMLYOSE STARCHES
 Genetic manipulation
 Form films and bind other ingredients
PECTINS AND GUMS
 Polysaccharides
 Plant tissue
 Used as gelling agents, thickeners,
stabilizers
PECTIC SUBSTANCES
 Part of primary cell wall
 Hold cells together, hold skin on fruit
 Protopectin - immature fruits
 Pectinic acid- mature fruit, includes
pectins
 Pectic acid - over ripe fruit
PECTIN
 Dispersible in water
 Forms a sol
 Can be converted to a gel in the
presence of water with addition of sugar
or acid
 Attraction to water is decreased
 Pectin under skin of fruits melts with heat
application (peel tomatoes, etc)
PECTINS
 Commercially extracted from apple cores
and skins; form white inner skin of citrus
fruits
 Boiling too long - depolymerization
occurs, gel may not set
 Boiling too short - insufficient invert
sugar formed, sucrose may crystallize
GUMS
 All are colloidal polymers (too large to dissolve)
 All are very hydrophilic
 All are thickeners in water dispersions
 Galactose most common sugar
 All are polysaccharides – EXCEPT for gelatin
 Examples: Guar gum, gum arabic, carob bean
gum, carageenan, agar, xanthan gum
USES
 Thickening agents replacing starch
 Stabilizers of emulsions
 Maintain smooth texture of products like
ice cream
 All do not form gels