NUFS 427: Lecture 14, Process-Induced Contaminants & Food Allergens and Food Safety

Pt 1: Process-Induced Contaminants

Pt 1: Process-Induced Contaminants

What are process-induced contaminants?

Compounds formed unintentionally during food processing or cooking.

What benefits can food processing provide?

Improved safety, sensory properties, and shelf life.

What are some common process-induced toxins/contaminants in food?

(Acrylamide)

Acrylamide, PAHs, benzene, chloropropanols such as 3-MCPD, furan, and 4-methylimidazole.

What is another name for acrylamide?

(Acrylamide)

2-propenamide.

What are the physical properties of acrylamide?

(Acrylamide)

Colorless and water-soluble.

What are some industrial uses of acrylamide?

(Acrylamide)

Production of plastics and paper and use in water treatment.

When was acrylamide first discovered in foods?

(Acrylamide)

2002.

How is acrylamide classified by IARC?

(Acrylamide)

Group 2A — probably carcinogenic to humans.

What foods commonly contain high levels of acrylamide?

(Acrylamide)

Fried potatoes, bread crust, biscuits, crackers, coffee, and breakfast cereals

Which food group generally has especially high acrylamide concentrations?

(Acrylamide)

Potato crisps and snacks.

During what reaction is acrylamide formed in foods?

(Acrylamide)

The Maillard reaction.

At approximately what temperature does significant acrylamide formation occur?

(Acrylamide)

Above about 120°C.

Why is acrylamide associated with fried, baked, and roasted foods?

(Acrylamide)

These processes use high, dry-heat temperatures that promote the Maillard reaction.

Is acrylamide normally detected in raw or boiled foods?

(Acrylamide)

No.

Why does boiling produce little or no acrylamide?

(Acrylamide)

The temperature is generally around 100°C, below the temperatures that strongly promote acrylamide formation.

How can acrylamide contribute to cancer risk?

(Acrylamide)

It is metabolized to glycidamide, which can form DNA adducts.

What are major strategies for reducing acrylamide in foods?

(Acrylamide)

Choose suitable potato/cereal varieties, blanch or leach potatoes, use enzyme treatment, lower cooking temperatures, and use appropriate additives.

How does blanching or leaching potatoes reduce acrylamide formation?

(Acrylamide)

It removes some acrylamide-forming precursors before frying.

What enzyme can be used to reduce acrylamide formation?

(Acrylamide)

Asparaginase, which reduces available asparagine.

What simple cooking strategy can consumers use to reduce acrylamide?

(Acrylamide)

Cook starchy foods to a lighter golden colour rather than excessive browning or burning.

What are polycyclic aromatic hydrocarbons (PAHs)?

(PAHs)

Large organic compounds containing two or more fused aromatic rings.

How are PAHs mainly formed?

(PAHs)

By the incomplete combustion of organic material.

What is PAH4?

(PAHs)

A commonly used indicator of PAH contamination in foods.

What food-processing methods can introduce PAHs into foods?

(PAHs)

Grilling, drying, smoking, baking, and frying.

What factors influence PAH formation in food?

(PAHs)

Temperature, fuel, oxygen availability, and smoke exposure.

Which is a greater dietary concern for PAHs: acute or chronic exposure?

(PAHs)

Chronic exposure.

Why are some PAHs a health concern?

(PAHs)

Some are genotoxic and carcinogenic.

How is benzo[a]pyrene classified by IARC?

(PAHs)

Group 1 carcinogen — carcinogenic to humans.

What determines gastrointestinal absorption of PAHs?

(PAHs)

The properties of the PAH and the composition of the food.

How does lipophilicity affect PAHs in the body?

(PAHs)

It facilitates their absorption and distribution into tissues.

How can PAHs damage DNA?

(PAHs)

Metabolic activation can produce reactive metabolites that bind to DNA.

What types of foods can contribute to dietary PAH exposure?

(PAHs)

Examples include cereals, fats, vegetables, meat, seafood, fish, coffee, tea, and cocoa.

How can PAH formation during grilling or smoking be reduced?

(PAHs)

Use lean cuts, prevent fat dripping, avoid charring/direct flames, and use indirect heating or smoking.

How can PAHs on fruits and vegetables be reduced?

(PAHs)

Wash or peel them to remove surface-deposited PAHs.

Why is there no tolerable daily intake for some PAHs?

(PAHs)

Because some PAHs are genotoxic carcinogens, so exposure should be kept as low as reasonably achievable.

What is the main idea for reducing PAH exposure from cooked foods?

(PAHs)

Reduce smoke contact, direct flame exposure, fat dripping, and excessive charring.

What three "hidden hazards" can form during storage, hydrolysis, or canning?

(Benzene & Chloropropanols)

Benzene, chloropropanols, and furan

In what type of food is benzene particularly associated?

Soft drinks and other beverages.

What ingredient combination can lead to benzene formation in beverages?

Benzoate preservatives + ascorbic acid (vitamin C).

What factors promote benzene formation in beverages?

Heat, light, and trace metals such as copper or iron.

How is benzene classified by IARC?

Group 1 — carcinogenic to humans.

What health effect is benzene particularly associated with?

Leukemia and other blood cancers.

How can benzene formation in beverages be reduced?

Reformulate products, use metal chelators such as EDTA, and store beverages cool and dark.

What benchmark has Canada used for benzene in beverages?

The drinking-water guideline of 5 µg/L.

What did Health Canada's 2007 beverage survey find?

Of 139 beverages tested, 3 were above 5 µg/L; manufacturers were notified and some products were reformulated.

What is the main chloropropanol of concern in foods?

3-MCPD (3-monochloropropane-1,2-diol).

What foods are especially associated with 3-MCPD?

Acid-hydrolyzed vegetable protein (acid-HVP) and soy sauce.

What other foods can contain chloropropanols?

Bread, biscuits, malt, coffee, roasted barley malt, salted/smoked foods, cheese, and cured or fermented meats.

How is 3-MCPD classified by IARC?

Group 2B — possibly carcinogenic to humans.

What is the concern with 1,3-DCP?

It has genotoxic and carcinogenic concerns.

What is Health Canada's maximum level for 3-MCPD in soy, oyster, and mushroom sauces?

1 mg/kg.

What very high 3-MCPD concentration was reported in a Canadian soy sauce survey?

Up to 330 mg/kg in a sample from the 1999-2000 surveys.

What contaminant is commonly associated with fries, potato chips, bread crust, and coffee?

Acrylamide.

What are the main precursors for acrylamide formation?

Reducing sugars + asparagine.

What triggers acrylamide formation?

High-temperature Maillard reactions.

What is the main way to control acrylamide formation?

Reduce its precursors and optimize heating time and temperature.

What contaminant is especially associated with grilled and smoked foods?

PAHs.

What causes PAH formation?

Incomplete combustion, pyrolysis, and smoke exposure.

How can PAHs be reduced during cooking?

Prevent fat dripping and charring and use indirect heating/smoking.

What combination can produce benzene in beverages?

Benzoate preservatives + ascorbic acid (vitamin C).

What promotes benzene formation in beverages?

Heat, light, and metal catalysts such as Cu or Fe.

How can benzene formation in beverages be controlled?

Reformulate the product and use cool, dark storage.

What are the main precursors for 3-MCPD formation?

Chloride + lipids/glycerol.

What processing condition promotes 3-MCPD formation?

High temperature, especially during acid hydrolysis or thermal processing.

How can 3-MCPD form in acid-HVP or soy sauce?

HCl reacts with lipids during acid hydrolysis of protein.

How can 3-MCPD form in bread and bakery products?

Chloride from salt reacts with glycerol from flour/yeast during baking.

What four processing changes can reduce 3-MCPD in acid-HVP?

Use enzymatic hydrolysis, lower-lipid raw materials, controlled acid hydrolysis, and validated treatment.

Does furan have one single precursor?

No. It can form through several heat-driven pathways.

What compounds can act as precursors for furan?

Reducing sugars, amino acids, ascorbic acid, polyunsaturated fatty acids, and carotenoids.

What foods are commonly associated with furan?

Canned foods, jarred foods, baby foods, and roasted coffee.

Why can canned foods retain furan after heating?

The sealed container prevents volatile furan from escaping.

What is unusual about furan's volatility?

It has a low boiling point of about 31°C.

How can furan concentrations be reduced before eating?

Open heating, stirring, and preparation can allow furan to volatilize.

What are the major health concerns associated with furan?

Liver toxicity and carcinogenic effects; it is classified as possibly carcinogenic to humans (IARC Group 2B).

What analytical method is especially useful for volatile and semi-volatile process contaminants?

GC-MS or GC-MS/MS.

What analytical method is useful for non-volatile, polar, or thermally unstable contaminants?

LC-MS/MS.

What steps may be required before analysing process-induced contaminants?

Extraction, cleanup such as SPE, and sometimes derivatization.

Why are internal standards used during contaminant analysis?

For accurate quantification.

What four characteristics should an analytical method be validated for?

Accuracy, precision, sensitivity, and selectivity.

Match these foods with their likely process-induced contaminant: toast/coffee, canned soup, vitamin-C soft drink, soy sauce, BBQ burger.

Toast/coffee → acrylamide; canned soup → furan; soft drink → benzene; soy sauce → 3-MCPD; BBQ burger → PAHs.

Why would a warm, light-exposed soft drink containing sodium benzoate and vitamin C be investigated for benzene?

It contains the reactive precursor combination, and heat/light promote benzene formation.

A chip manufacturer stores potatoes at 4°C and increases frying from 165°C to 180°C. What contaminant is of concern?

Acrylamide—cold storage can increase reducing sugars, while higher frying temperature increases Maillard reactions.

What are two practical ways to reduce acrylamide in potato chips?

Avoid excessively cold potato storage and reduce/optimize frying temperature and browning; blanching can also remove sugars.

Why might increasing coffee roasting intensity to reduce one contaminant not reduce all process-induced contaminants?

Different contaminants have different precursors and formation pathways, so changing heat treatment may reduce one while increasing another.

Pt 2: Food Allergens and Food Safety

Pt 2: Food Allergens and Food Safety

What is a food allergy?

An immune-mediated reaction to specific proteins in a food.

What happens during a food allergy?

The immune system mistakenly treats a food protein as harmful and triggers an immune response.

What antibody is commonly involved in immediate food allergies?

IgE.

What happens when IgE recognizes an allergen?

It activates mast cells, causing release of mediators such as histamine.

What are the four major categories of food allergy symptoms?

Skin, respiratory, gastrointestinal, and cardiovascular.

How quickly can food allergy symptoms appear?

Within minutes, although some reactions may occur several hours after exposure.

Can the severity of an allergic reaction be predicted from previous reactions?

No. Symptoms and severity can vary between reactions.

Why must even mild food-allergy symptoms be taken seriously?

They can progress rapidly to a severe reaction.

What is anaphylaxis?

An acute, life-threatening, rapidly evolving systemic allergic reaction.

What commonly triggers food-related anaphylaxis?

Ingestion of a specific allergenic food.

How quickly can anaphylaxis develop?

Usually within seconds to minutes of exposure.

Why can untreated anaphylaxis be fatal?

It can rapidly progress to respiratory and/or cardiovascular collapse.

What are common signs of anaphylaxis?

Throat tightness, swelling, wheezing, trouble breathing, hives, vomiting, weak/rapid pulse, and pale or flushed skin.

What is a food intolerance?

A generally non-immune adverse response to food that causes uncomfortable symptoms.