Types of Food PreservativesMaintaining freshness

Preservatives – substances add to food to prevent or slow spoilage and maintain natural colors and flavors

• 2 reasons for food spoilage– Microbial contamination

– Fats reacting with oxygen (Oxidation)

• Preservative criteria:– Nontoxic

– Functional

– Flavorless

– economical

Antimicrobial agents – prevent the growth of microbes in food• Salts and sugars– Oldest and most used types

– Dehydrate food (microbes can’t grow without water

• Nitrates (NO3)– NaNO3 most common

– Controls the bacteria that cause botulism

– React with amino acids to form nitrosamines (carcinogen) • Illegal according to Delaney act but risk of botulism to high• Legislation allows use until safe alternative found

Antimicrobial agents cont.• Acids– Acetic, ascorbic, citric, lactic, benzoic, and propionic

– Prevent microbe growth by lowering pH of food

– Calcium propionate (C6H12CaO5) prevents mold in bread

– Sorbic (C6H8O2)and benzoic acid (C6H6O2) work together• Control mold, yeast, and bacteria in soft drinks

Antioxidants• Protect foods from changes caused by exposure to

oxygen

• Interfere with the formation of free radicals– Atoms or groups of atoms with 1 or more unpaired

electrons• They are unstable and highly reactive• Cause fats to become rancid ad trigger enzymatic browning• Can cause the formation of carcinogens

• Antioxidants donate hydrogen atoms to free radicals– Create a stable compound

see pages 467-468 for more info on Antioxidants

Sulfites• Controversial group of antioxidants

• Salts that contain sulfur– Sulfur dioxide, sodium sulfite, sodium and potassium

bisulfite

• Added to frozen and dried produce to prevent browning

• Use on fresh produce banned by FDA 1986– Dangerous allergic reactions

• Can’t be used on foods that are a source of thiamin– Sulfites destroy thiamin