Food Chemistrymajor part of the
discipline of studyFood 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 1.3• Sucrose 1.0• Glucose 0.56• Galactose 0.4-0.6• Maltose 0.3-0.5• Lactose 0.2-0.3
CHO - Sweetness• Lactaid
– Lactose or– Galactose and glucose
• Carbonated beverage– High fructose
corn syrup– Sucrose
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
TriglycerideDiglyceride
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
• Calcium• Iron• Sodium• Trace minerals
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