1. + + +

2. CHO

3. Food carbohydrates (CHO)
All CHO contain C,H and O. The basic building block of CHO is “simple” sugar,
that is also termed organic alcohol.
CHO exist as monosaccharide (a single sugar molecule not chemically bonded
to other sugar molecules), disaccharides, Oligosaccharides, or
Polysaccharides.
Monosaccharides
3 carbon atoms
(trioses)
5 carbon atoms
(pentoses)
6 carbon atoms
(hexoses)
Important monosaccharides found in foods are hexoses: glucose, fructose
and galactose; sharing formula C6H12O6.

4. Structures of simple sugars.

5. Although the hexoses share the same formula, slight differences in the location
And functional groups cause differences in functional properties (see structure).
Fructose, existing as a 5-membered ring structure is sweeter and more soluble
Than glucose (6-membered ring; sometimes called dextrose).
Monosaccharides are the basic units around which larger CHOs are built.
Disaccharides
2 Monosaccharides joined together (via glycosidic bond) to form a disaccharide.
The three most important food disaccharides are:
a) Sucrose (glucose and fructose), a common table sugar,
b) Lactose (glucose and galactose) found in milk, and
c) Maltose (glucose and glucose).

6. Structures of disscharides

7. Functional properties of sugars
Sugar molecules contain 2 important, reactive functional groups:
Carbonyl group: reducing and Maillard browning (color and flavor).
Alcohol group: readily forms hydrogen bonds with water molecules, thus contribute to solubility.
Glucose has 5 OH groups, thus very soluble. OH also contribute to sweetness.
Reducing sugars
Sugars that contain the aldehyde or ketone carbonyl groups; all monosaccharides and certain disaccharides are reducing sugars.
Dextrose equivalent (DE): a measure of % of glycosidic bonds hydrolyzed in
disaccharides or polysaccharides, which indicates the level of reducing sugar
Present.
Pure dextrose: DE value of But, Starch: DE value of 0. The higher the DE,
the more soluble and the greater the reducing ability of a sugar.

8. This is due to sugars

9. Browning Caramelization: Maillard browning*:
Reaction of reducing sugar
With amino acids at low (long storage time)
to high processing temperatures, producing
Brown color pigments (melanoidins)
Caramelization:
Formation of brown caramel pigments
(caramelen, C24H36O18)
As a result of applying heat energy to
Sugars. Typical
Temperature is > 200°C.
Desirable:
Aroma, brown
Surface, flavor
Undesirable:
Unwanted browning/
Off-odors/polymerization/
Texture toughening/ alleged
Free radicals etc
Also known as nonenzymic browning because enzyme is not part of the reaction
Why “Maillard” name?
Flavor, brown color
HOT:
Dodol?
Coke?
Roast beef?

10. Desirable: Undesirable:
Crystallization.
Sugars can exist in 2 states: crystalline  syrup (soluble).
Crystallization: When units of sugar organize in 3-D arrays into a solid form.
A crystal: a solid made up of sugar units in a repeating pattern (see figure).
Crystalline structure
Desirable:
Purification of sugar during manufacture
of table sugar/
manufacture of hard candy where
sugar melts upon heating and
recrystallize when cooled into different
crystal size and form.
Undesirable:
Formation of large sugar
crystals in ice cream/
condensed milk yielding
coarse and gritty texture
(or graining)

11. Boiled at low temperature Under vacuum + seeding
Clarified sugar cane
Boiled in evaporator
Thick syrup
Boiled at low temperature
Under vacuum
+ seeding
Development of sugar
Crystals (with molasses)
Growth of sugar
Crystals (with molases)
Centrifugation
Sugar
Crystals
Molasses

12. Crystallization:
formation of solid crystal precipitating from a solution or melt
2 events: nucleation, and then crystal growth.

13. Humectancy
Humectant?:
A substance that has affinity for moisture (and are thus hygroscopic – able to attract and retain moisture).
Able to hydrogen bond with water molecules, making water less available for microbial growth, thus help to preserve foods.
CHO, especially sugars are used in food to influence the state of water.
a) fructose is more hygroscopic than sucrose, and is thus used to reduce Aw in food systems.
b) Sucrose is less hygroscopic, and is thus free-flow more easily during dry-mixing or packaging (of dry products) compared to fructose.
Inversion
The hydrolysis of sucrose to its component monosaccharides or invert sugars that are sweeter than sucrose alone. Sometime an enzyme invertase is added to invert sucrose.

14. Oligosaccharides: Polysaccharides:
Polysaccharides and their functional properties (general)
Size and
Complexity
Of their
structures
Complex CHO are composed of joined sugar units
Oligosaccharides:
10 or fewer sugar units;
Non-reducing.
Example: raffinose, stachyose.
Poorly digested, and thus fermented
In large intestine (yielding gas
And may cause flattulence).
Beans, soybeans, peas.
Polysaccharides:
40 or more sugar units.
Potentially hundreds more!
May contain reducing and
Non-reducing ends (susceptible
To enzyme attack).
Occur more frequently than
Oligosaccharides.
Important food polysaccharides:
Beta-glucan, cellulose, dextrins,
FOS, maltodextrins, pectic substances,
Starch, vegetable gums.
Will be covered
More In depth in food
chemistry

15. HOT
Differences between Nutrition facts and Ingredients
Find complex CHO: