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Food Chemistry
major part of the
discipline of study
Food Science
To assure the quality of foods
and develop new food products
the Food Scientist must
understand Food Chemistry
and
the primary compounds
in foods which are
carbohydrates, lipids
and proteins
CARBOHYDRATES
• Sugars
• Starches
• Dietary fiber
– Cellulose
– Gums
– Pectin
CARBOHYDRATES
• Sugars
– Monosaccharides
• Glucose
• Fructose
• Galactose
– Disaccharides
• Sucrose - - - - Table sugar
– Glucose and Fructose
• Lactose - - - - Milk sugar
– Glucose and Galactose
• Maltose - - - - Corn sugar
– Glucose and Glucose
CARBOHYDRATES
• Sugars
– Sweetness
•
•
•
•
•
•
Fructose
Sucrose
Glucose
Galactose
Maltose
Lactose
1.3
1.0
0.56
0.4-0.6
0.3-0.5
0.2-0.3
CHO - Sweetness
• Carbonated
beverage
– High fructose
corn syrup
– Sucrose
• Lactaid
– Lactose or
– Galactose and
glucose
CHO - Solubility
• Candy
– Invert sugar
– Caramel
– Hard candy
• Ice Cream
– Lactose
– Sucrose
– HFCS
CHO – Corn Syrup
• Contains both
– Corn syrup
and
– HFCS
– acid pH
• Changes
– Flavor
– Solubility
CHO - Starch
• Amylose
– straight chain of glucose
• Amylopectin
– branched chains of glucose
CHO - Hydrocolloids
• Hydrocolloids
include gums and
pectin
• Trap water and
form gels or make
products viscous
• Used at low
concentrations
CHO - Bread
• Starch in bread
helps produce the
texture
• Sugars form
brown crust
• Fiber in whole
grains
LIPIDS or FAT
• Glycerol (3 carbon) alcohol
• Fatty acids attach to alcohol
with ester bonds
Triglyceride
Diglyceride
Monoglyceride
Fat
•
•
•
•
Water insoluble (Non-polar)
Smaller molecules
Mix between CHO and/or Proteins
Produce creamy or soft texture
Fat – Fatty acids
• Chains of Carbon atoms with
Hydrogens attached
• If every C has 2 H attached the fatty
acid is saturated
H H H H H H H H
H C – C – C – C – C – C – C – C - OH
H H H H H H H H
Fat – Fatty acids
• If two C have a double bond so only
1 H attached the fatty acid is
monounsaturated
H H H
H H H
H C – C – C – C = C – C – C – C – OH
H H H H H H H H
Fat – Fatty acids
• If there are more than one double
bond the fatty acid is polyunsaturated
H
H
H
H
H
H
H
H
H C – C – C – C = C – C – C = C – C – C – C – C – OH
H H H H H H H H H H H H
FAT - Oxidation
• Double bond is less stable and
Oxygen molecules can attach to
unsaturated fatty acids
FAT - Oxidation
• Prevent or slow oxidation by
– Hydrogenating unsaturated fatty acids
(add hydrogens to double bonds)
– Vacuum package foods
– Packages that block or absorb light
– Keep products cool
– Add antioxidants
FAT – Melting point
• The type of fatty acids
will affect the melting
point of the fat
REDUCED FAT – Ice Cream
• Remove some or
all fat in food
products
• Add other
ingredients to
give acceptable
texture
• Gums are added
to this ice cream
PROTEIN
• Made of varying amino acids
• Amino acids contain Nitrogen
PROTEIN – Bakery Items
• The amount of protein will affect
the texture of bakery products
• Protein is tougher than starch
• Flour to make pasta has highest
amount of protein
• Flour to produce bagels in
higher than flour used to
produce bread
PROTEIN - Denaturation
• Peptide bonds can be broken
apart if the temperature is higher
• Peptide bonds can also be
broken apart by acid
PROTEIN - Denaturation
• Diet beverages
contain aspartame
• Aspartame is two
amino acids
• The shelf-life is
therefore shorter
than for sugar
sweetened drinks
PROTEIN - Cheese
• Proteins are charged
molecules
• If the charge is neutral
the protein will
precipitate or coagulate
• The isoelectric point for
Casein (milk protein) is
approximately 4.5.
• At this pH curd forms
and is used to make
cheese
PROTEIN - SALT
• Some proteins
are salt soluble
• Increased salt
content extracts
proteins from
meats and these
proteins can act
like a “glue”
MOISTURE - Popcorn
• Water content is an
important factor in
many foods
• Amount and size of
pop corn depends on
proper moisture
content
COLOR - PIGMENTS
• Different foods contain
various pigments
• Broccoli
– chlorophyll
• Red Cabbage
– anthocyanins
• Carrots
– Beta carotene
Vitamins
• Fat soluble
– Vitamins A, D, E, K
• Water soluble
– Vitamin C
– B vitamins
Minerals
•
•
•
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Calcium
Iron
Sodium
Trace minerals