Preservatives and Food Safety Quiz

Preservatives - Food Chemistry

• Preservatives are used to protect food from harmful microorganisms.
• The use of preservatives is common in food production and processing to maintain quality and extend shelf life.
• Microorganisms have similar nutritional requirements to humans.
• Microorganisms obtain energy via photosynthesis or oxidation/fermentation of organic compounds.
• Microorganisms thrive in moderate pH and temperature conditions, which are common in food products.

Introduction - Food Safety

• Food safety is a crucial aspect of food science.
• Foodstuffs are excellent environments for pathogenic and toxin-producing bacteria.
• Chemical preservation methods are important and target unwanted microbial activity.
• Heat processing methods can damage or destroy nutrients.

Antimicrobial Procedures

• Multiple mild antimicrobial procedures are typically combined.
• This strategy aims to maximize microbial inhibition while minimizing negative impacts on nutritional and organoleptic quality.

Cooked Ham Preservation Methods

• Salt: Maintains low water activity.
• Nitrite: Prevents spore and bacterial growth.
• Cooking: Destroys vegetative bacterial cells.

Sodium Chloride (Common Salt)

• Sodium chloride was the first antimicrobial substance used in food preservation.
• It's utilized as a preservative and flavoring agent.
• The importance of salting has diminished with advancements in refrigeration and canning.

Nitrites

• Nitrates and nitrites are essential components of salt mixtures used in curing meat.
• Nitrites create the attractive red/pink color in preserved meat.
• Recent concerns exist about the risk of carcinogenic nitrosamine formation when using nitrates in food.
• Adding ascorbic acid during curing can reduce nitrosamine formation.

Nitrite Reactions in Muscle Tissue

• Some nitrates are reduced to nitrites by enzymes in muscle tissue.
• Nitrite oxidizes iron in myoglobin to metmyoglobin.
• Nitrogen oxide reacts with MMb, forming nitrosyl metmyoglobin (MMbNO).
• MMbNO is quickly converted to nitrosyl myoglobin (MbNO).

Smoke Preservation

• Smoke, derived from wood, is a traditional meat and fish preservative.
• The flavoring aspect of smoke was initially recognized as its primary function.
• Preservation via smoke was less impactful.
• Smoke contains antimicrobial formaldehyde (methanol).
• The use of smoke for preservation is less common in recent years; refrigeration is more prevalant.
• Carcinogens in wood smoke have raised concerns about the safety of smoked foods.
• Liquid smoke alternatives are used increasingly.

Sulfur Dioxide (SO2)

• SO2 is used in wine-making to control the growth of unwanted microorganisms.
• Typical SO2 levels in wine are around 100 ppm.
• The desirable yeast Saccharomyces cerevisiae thrives in these conditions; undesirable yeast and lactic-acid bacteria are controlled.
• Though effective, high SO2 levels can cause allergic reactions.
• The bisulfite ion reacts with thiamin (vitamin B1).
• SO2-treated vegetables may reduce their vitamin B1 content.
• Many regions restrict SO2 usage in foods rich in vitamin B1.

Benzoates

• Benzoic acid is a naturally occurring preservative in some plants, notably cloudberries.
• Sodium benzoate (more soluble than benzoic acid) is a common food preservative.
• Benzoic acid is added usually to low-pH foods (up to pH 6.5), such as fruit juices.
• The levels typically used (0.05-0.1%) are considered safe for human consumption.

Sorbic Acid, Acetic Acid, Propionic Acid

• Sorbic acid is a mold inhibitor.
• Acetic acid is a spoilage bacteria and fungi inhibitor.
• Acetic acid is ubiquitous in vinegar and becoming more common as an anti-mold ingredient in bread.
• Propionic acid inhibits molds, naturally found in some foods, and similar to acetic acid in its antimicrobial activity.

Nisin

• Nisin (a 34-amino acid polypeptide) is produced by Streptococcus lactis bacteria.
• Nisin is commonly used in processed cheeses.
• Nisin is an antimicrobial but is not typically used to treat diseases.

Natamycin

• Natamycin is an antifungal antibiotic made by Streptomyces natalensis.
• Natamycin has limited clinical use but is used to prevent unwanted mold growth in cheese.