Preservatives and Food Safety Quiz

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Questions and Answers

What is formed when nitrite oxidizes the iron in myoglobin?

Deoxymyoglobin

Ferrimyoglobin

Metmyoglobin (correct)

Nitrosyl myoglobin

Which compound is formed from the reaction of nitrogen oxide with metmyoglobin?

Metmyoglobin nitrate

Nitrosyl metmyoglobin (correct)

Nitrosyl myoglobin

Hemoglobin

What pigment is associated with nitrosyl myoglobin in uncooked bacon and ham?

Green pigment

Red/pink pigment (correct)

Brown pigment

Yellow pigment

What antimicrobial compound is predominantly found in wood smoke?

Formaldehyde Signup and view all the answers

What is the typical level of sulfur dioxide used in wine-making?

100 p.p.m. Signup and view all the answers

Which nutrient is significantly affected by the presence of sulfur dioxide in food?

Vitamin B1 Signup and view all the answers

What is the primary reason sodium benzoate is preferred over benzoic acid in food preservation?

It is more soluble than benzoic acid. Signup and view all the answers

Which of the following acids is known to inhibit mold growth effectively?

Sorbic Acid Signup and view all the answers

At what concentration range is sodium benzoate typically used as a food preservative without detecting deleterious effects?

0.05-0.1% Signup and view all the answers

Which type of food can have benzoic acid added to it effectively?

Low pH foods like fruit juices Signup and view all the answers

What is the primary purpose of using preservatives in food?

To deter unwanted microbial activity Signup and view all the answers

Which of the following is NOT mentioned as a mild procedure used to protect food?

Freezing the food Signup and view all the answers

What is the main reason for adding nitrites in the curing process of meats?

To prevent spore and bacterial growth Signup and view all the answers

How does sodium chloride primarily function as a preservative?

By lowering water activity Signup and view all the answers

Why has the use of nitrates in food preservation come under scrutiny recently?

They may lead to the formation of carcinogenic nitrosamines Signup and view all the answers

What chemical transformation occurs to some of the nitrate in food preservation?

It is reduced to nitrite by muscle tissue enzymes Signup and view all the answers

Which of the following statements about the use of preservatives is true?

They often combine multiple mild procedures for effectiveness Signup and view all the answers

What is one effect of adding ascorbic acid in curing salts?

Reduces nitrosamine formation Signup and view all the answers

Study Notes

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.

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Description

Test your knowledge on the role of preservatives in food chemistry and the importance of food safety. Explore how various antimicrobial procedures work to inhibit harmful microorganisms while preserving the nutritional value of food. This quiz covers essential concepts regarding food preservation techniques and microbial activity.