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CARBOHYDRATES SUGARS, STARCHES, PECTINS, AND OTHER CARBOHYDRATES.

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Presentation on theme: "CARBOHYDRATES SUGARS, STARCHES, PECTINS, AND OTHER CARBOHYDRATES."— Presentation transcript:

1 CARBOHYDRATES SUGARS, STARCHES, PECTINS, AND OTHER CARBOHYDRATES

2 CHARACTERISTICS  Organic compounds  Carbon, Hydrogen, Oxygen  Simple or complex  Source of energy or fiber  Important food CHOs - Sugars, dextrins, starches, celluloses, hemicellulose, pectins, gums

3 FUNCTIONS  SWEETENERS  THICKENERS  STABILIZERS  GELLING AGENTS  FAT REPLACERS

4 MONOSACCHARIDES  SIMPLE SUGARS  MOST COMMON - 5 OR 6 CARBON

5 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

6 FRUCTOSE  Levulose  Part of sucrose  Sweetest of all sugars  In many fruits  Very soluble  Not easily crystallized  Glucose isomerase to change glucose to fructose

7 GALACTOSE  Part of lactose – milk sugar  Basic unit of pectic substances  Building block of many vegetable gums

8 COMMON MONOSACCHARIDES

9 DISACCHARIDES  Two monosaccharides  Glycosidic bonds-readily hydrolyzed by heat, acid, enzymes

10 SUCROSE  Table sugar  From sugar cane or sugar beet  Glucose + fructose  Invert sugar important in controlling crystallization  Most common disaccharide

11 MALTOSE  Glucose + glucose  Product of starch breakdown  Corn syrup  Flavoring and coloring agent in beer, candies, shakes

12 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

13 DISACCHARIDES

14 PROPERTIES OF SUGAR

15 SOLUBILITY  Solution in foods  Varying degrees of solubility for 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 F ( C)  Can use temperature to determine sucrose concentration

16 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

17 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

18 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

19 HYGROSCOPICITY  Ability to absorb moisture  Responsible for lumpiness (sugar)  Decreases staling in bread  Gives stickiness for high moisture characteristics to foods  Fructose most hygroscopic

20 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

21 TYPES OF SUGARS CRYSTALLINE AND NON- CRYSTALLINE

22 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

23 POWDERED SUGAR  Pulverized granulated sugar  Add cornstarch to prevent caking  X designates fineness

24 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

25 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

26 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

27 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

28 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

29 SUGAR COOKERY CANDIES

30 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

31 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

32 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

33 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

34 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

35 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

36 STRUCTURE AMYLOSE AND AMYLOPECTIN

37 AMYLOSE  Straight chain or linear fraction  1/4 of all starch  Thousands of glucose units  Forms thick gels-hold shape when molded, rigid

38 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

39 AMYLOPECTIN

40 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

41 EFFECTS OF HEAT

42 DRY HEAT  Heating - increases uptake of water  Dextrinization  Color and flavor changes  Reduced thickening power  Nonenzymatic browning  Dry flour browned

43 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

44 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

45 CONTINUED HEATING  Gelatinization requires addition of heat  Cooking develops flavor  Pasting occurs  Granules swell  Granules of starch swell independently

46 PASTE CHARACTERISTICS  Concentration of starch affects consistency  Clear thickened gel made from root starches or waxy versions of starches  Cloudy gels from cereal starches

47 FACTORS AFFECTING GELATINIZATION

48 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

49 AGITATION  Over-stirring causes granules to burst, empty bound water = gel will thin  Creates more uniform mixture

50 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

51 TIME AND TEMPERATURE  Lengthen heating time = causes granules to rupture - thins product  More rapid heating = smoother paste  Bring to boil over direct heat

52 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

53 SEPARATING AGENTS  DEFINED - ingredients or additives which physically 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

54 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

55 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

56 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

57 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

58 HIGH AMLYOSE STARCHES  Genetic manipulation  Form films and bind other ingredients

59 PECTINS AND GUMS  Polysaccharides  Plant tissue  Used as gelling agents, thickeners, stabilizers

60 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

61 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)

62 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

63 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

64 USES  Thickening agents replacing starch  Stabilizers of emulsions  Maintain smooth texture of products like ice cream  All do not form gels


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