FDSC 2000 : Exam 2 Study Guide
FDSC Exam 2 Study Guide
Spring2011
Page 1 of 19
Chapter 5 Concepts
• Simple Sugars: composed of carbon, hydrogen, and oxygen
- Organic Alcohol- molecule attached to an OH group
- Mono-saccharides- the building blocks of all other carbohydrates
- Disaccharides- two carbohydrate units joined together
• Mono-saccharides
- Trisoses- contain 3 carbons
- Pentoses- contain 5 carbons
- Hexoses- contain 6 carbons; the most important in food
▪ Glucose, fructose, galactose – all share the same chemical formula C₆H₁₂O₆
- Can exist as either a Fischer projection molecule( a straight chain of carbons) or as a Ring
structure ( most common in solution)
- Structural features depend on the location of functional groups and influence functional
properties
▪ Ex. glucose and fructose are both hexoses
Glucose has a 6 member ring, an aldose
Fructose has a 5 member ring, a ketose
▪ This is why fructose is sweeter and more soluble than glucose
• Disaccharides
- Made up of two mono-saccharides bonded together by a glycosidic bond
- 3 most common disaccharides
▪ Sucrose- (glucose +fructose) common table sugar
▪ Lactose- (glucose + galactose) milk sugar
▪ Maltose- (glucose + glucose) common breakdown product from starch
• Functional properties of sugars
- Alcohol (OH)- important for solubility and sweetness
▪ The OH group has a great influence on sweetness and other functional properties
because of the way it can participate in hydrogen bonding
- Carbonyl (C=0)- important for reducing activity and Maillard Browning for color/flavor
development
• Reducing sugars
- Contain a carbonyl group
▪ All mono-saccharides are reducing sugars
- Dextrose equivalent (DE)- indication of the amount of free ( hydrolyzed) glucose, which is an
indication of solubility, reducing action, viscosity, etc.
▪ Pure dextrose has a DE of 100, while starch has a value of 0
▪ The higher the DE the mire soluble and greater reducing ability of the sugar
• Browning
- Two important browning reactions
1. Maillard Reaction
2. Caramelization
FDSC Exam 2 Study Guide
Spring2011
Page 2 of 19
- Both are Non-enzymatic Browning because enzymes are not involves in the reactions
• Maillard Browning
- complex series of reactions that requires a reducing sugar and amino acids in foods
- the browning of foods as a result of the Maillard reaction
▪ intermediate products: pyrazines , which tend to have pleasant aromas and flavors
▪ end products: brown pigments called melanoidins
irreversible and results in darkening of food
unpleasant flavors and aromas can develop as well
230F
- Responsible for both positive and negative quality attributes
Good: in baked goods, the brown color and flavor products
Bad: in dried egg whites and instant mashed potatoes, considered undesirable
- Takes place at relatively low temperatures and can be accelerated by lower molecular weight
sugars, low moisture content ( 15%) and in pH range of 5.8
1. Condensation: reducing sugars + amine → glycosylamine
2. Rearrangement: glycosylamine →colorless intermediate compounds
3. Polymerization: colorless intermediate compounds→ brown melanoidin polymers
• Caramelization
- Takes place at high temperature ( 200C) and is due to the dehydration of the sugar molecule
which results in brown color and characteristics
- Protein/ enzymes are not required for this reaction
- “caramel” is referring to the brown coloring used in the food industry as well as sauces and or
candies made from carbohydrates that have been allowed to caramelized
• Crystallization
- Implies organized 3-D arrays of unit cells into solid form ( basis of candy manufacturing)
- In foods that contain solubilized sugars (ice cream) it is undesirable for the sugars to crystallize
because it cause a grainy texture
- Controlling this in candy manufacturing is very important to the quality of product
- Can be controlled by interfering agents
• Humectancy
- A substance that hasan affinity for moisture, also referred to as a hygroscopic substance
- Most carbohydrates especially simple sugars can be used as humectants
- This is related to their ability to form hydrogen bonds which reduces the amount of water
available for microbial growth ( fructose is more hygroscopic that sucrose so it can be added to a
food product to reduce the water activity, thus extending the shelf life)
• Inversion
- The process where sucrose is hydrolyzed to fructose and glucose which are then referred to as
invert sugars
- Caused by heat, acid, or invertase
FDSC Exam 2 Study Guide
Spring2011
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- Desirable when in browning reactions, flavor or increased wetness is needed, but can also cause
undesirable effects for similar reasons
• Oxidation & Reduction
- Reactions that promote important functional characteristics
- Oxidation of an aldehyde inn causes loss of sweetness and converts to acid
- Reduction of carbonyl of reducing sugar cause formation of sugar alcohols which are
moderately sweet ( mannitol and sorbitol)
• Sweetness & Texturizing
- Sweetness: sucrose is used as the reference with other sugars; fructose is sweeter than sucrose
and lactose is less sweet. Fructose sucrose glucose maltose lactose
- Texture mainly derived from simple sugar’s interaction with water
- Sugar can be provided in bulk, tenderization, and can influence other texture promoting
compounds such as starch
• Polysaccharides
- Complex carbohydrate
- Oligosaccharides- (3-10units)
▪ Rattinose and stachyose present in dried beans and are primarily responsible for
intestinal discomfort and gas ( because they aren’t digested in small intestine they are
fermented in the large intestine by microorganisms)
- Polysaccharides- (> 10units)
▪ much more abundant in foods than oligosaccharides and are commonly used as
additives to food for specific aspects of functionality usually related to textural
properties
• Beta-glucans
- Polymers of glucose
- Soluble dietary fiber
- Found in oats
- Used as fat replacers in manufactured products
Oatrium – used in baked goods, fillings and frostings, frozen desserts, salad dressings
• Cellulose
- Linear polymer of glucose
- Most abundant of all carbohydrate polymers because it is the structural component of all plant
cells
- Source of insoluble dietary fiber
- Microparticulate form of cellulose
▪ Used as bulking agent and to increase dietary fiber in foods
▪ Used as non-caloric fat replacer in salad dressing ( when dispersed it forms a network of
particles with the flow properties and mouth-feel of fat
• Dextrins &Maltodextrins
- Both derived from the breakdown of starch ( shorter glucose chains that starch but are still
polysaccharides)
