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