Food Science Exam 3

Lectures 1-9

Why do we need food laws?

It protects public health, ensure fair compeition, and guide daily plant decisions.

Examples of instances when we need food laws:

Adulteration, false advertising, misbranding, and spoilage/contamination

What is a law

A congressional act (rule of conduct)

What is a regulation 

An agency prescription (detailed rules) 

What’s the main goal behind having laws and regulations

Protect the consumers from fraud

What was the “poison squad”

It was a series of human trials conducted by a chemist to demonstrate to the US government the need for food regulations. Twelve volunteers consumed various substances commonly found in food, and the effects were documented.

What was the timeline in the early 20th century that laid the foundations of food law? 

1. 1906: Pure Food and Drug Act 

2. 1906: Federal Meat Inspection Act (FMIA) 

3. 1938: Food, Drug, and Cosmetics Act (FD&C Act) 

What is the pure food and drug act? When was it established?

This act was responsible for adulteration, misbranding, and unsanitary condition.

Established in 1906.

What is the federal meat inspection act and when was it established?

This act banned unsafe/misleading food and drug sales, and mandated meat inspection.

This was established in 1906.

What is the food, drug, and cosmetics act? When was it established? 

It replaced both the 1906 acts. It granted the FDA regulation over a wide range of products, including food, drugs, cosmetics, and other things. It provided a standard that companies had to follow and set a schedule of factory inspections. 

Established in 1938. 

What’s the timeline for food laws in the mid-20th century that expanded protection?

1. 1950s:

   1. Poultry Inspection Act (1957)

   2. Food Addictive Amendment (1958)

2. 1967: Fair Packaging & Labeling Act

3. 1970s: EPA was established, and the USDA was formed

What did the Poultry Inspection Act of 1957 and the Food addictive amendment of 1958 accomplish? When were they both established? 

They ensured the chemical safety of additives. 

Poultry inspection was established in 1957, and food addictive were established 3 years later in 1958. 

What was the fair packaging & labeling act? When was it established?

This act addressed deceptive packacing and laid standards for labeling, which included clear ID and net weight.packaging

Established in 1967.

What is the EPA? USDA? When were they established?

EPA was established to protect human health and the environment. Focuses on pesticide inspection used in food products.

USDA was established specifically for meat and poultry inspection.

Both organizations were established in the 1970s/

What’s the timeline for the modern era of food laws regarding prevention and information?

1. 1990: Nutrition Labeling & Education Act (NLEA)

2. 2011: Food Safety Modernization Act (FSMA)

What was the nutrition labeling & education act? When was it established? 

This act enforced nutrition label as a mandatory aspect of food. It helped standardized health claims. 

Established in 1990. 

What was the food safety and modernization act? When was it established?

This act shifted food laws more towards preventative controls and comphrensize food supply oversight. The FDA focused more on preventing food saftey problems earlier rather than later.

Established 2011.

What does the FDA do?

Scope: Most foods; labelingl GCMP; imports

Example trigger: allergen mislabeling in cookies, radioactive substances

Typical actions: warning letters; recalls; import alerts

What does the USDA do? 

Scope: meat, poultry, some egg products

Example trigger: undercooked ground beef outbreak 

Typical Action: public health alerts; recalls; inspections 

What does the CDC do?

Scope: surveillance & coordination

Trigger: multi-state illness cluster

Actions: Epi investigation; case definition; coordination

What does the EPA do?

Scope: pesticide tolerance; water

Trigger: residue above tolerance

Actions: Set/enforce tolerance; notices

What does the FTC do? 

Federal Trade Comission 

Scope: advterising practices 

Trigger: deceptive weight-loss ads

Actions: investigations; consent orders 

What’s the process of FSMA in practice?

Food Saftey Moderinization Act

1. Hazard Analysis

2. Preventive Controls

3. Monitoring

4. Corrective Actions

5. Verification

6. Recordkeeping

What is a class I risk? 

Reasonable probability of serious adverse health consequences or death 

Ex: undecleared allergens in cookies 

What’s a class II risk?

Temporary or reversible in health consequences.

Ex: Minor contamination, not likely to cause serious harm.

What’s a class III risk?

Not likely to cause adverse health consequences.

Ex: labeling error with no health impact.

What’s the recall decision flow? 

1. detect issue 

2. assess risk

3. classify 

4. notify press 

5. execute recall 

6. verify effectiveness

What are examples of state agencies?

Department of Agriculture & the Department of Health

What are examples of local agencies?

• City or country health inspections (health departments)

• Inspect at restaurants, giving health rating scores

  • Can shut down restaurants.

Mandatory Food Labeling

• correct statement of identity 

• correct net weight 

• ingredients are described in descending order by weight 

• manufacter’s information is an important in food labeling

What are the 14 nutrient facts that must be specificed on all labels?

1. calories

2. calories from fat

3. total fat

4. saturated fat

5. cholesterol

6. sodium

7. dietary fiber

8. total carbs

9. sugar

10. protein

11. vit a

12. vit c

13. calcium

14. iron

what does date code “use by/best if used by” mean?

• quality window by manufacter

• often saftey-relevant

• used on meats, eggs, and fresh juices

what does date code “best before” mean?

• best quality date 

• generally not safety-related 

• used on dry snacks, goods

what does date code “display until/sell by” mean?

• retail stock rotation

• not consumer safety date

• used in dairy products and bakeries

Food laws takeaway

• U.S. food laws evolved to solve concrete problems

• agency jurisdiction matters:

  • FDA: most foods/labels

  • USDA: meat & poultry

  • CDC (surveillance)

  • EPA (tolerances)

  • FTC (ads)

• NLEA basics:

  • Serving size drives numbers

  • %DV aids comparison

  • claims must meet a defined threshold

• date codes:

  • “use by” = safety-relevant

  • “best before” = quality

  • “sell by” = retail rotation

• FSMA: prevent, verify, document

• Imports/FSVP: know your supplier, verify risks, keep evidence

• When in doubt: match the scenario to the right agency, cite the rule, and document ur decision

What is food safety? 

• practices to ensure food is safe for consumers 

• prevents contamination from farm to fork 

• aims to stop foodborne illnesses 

Are the 3 types of food safety hazards?

1. Biological

2. Chemical

3. Physical

What are biological hazards?

• caused by pathogens in food

• ex: Samonella, E. Coli, Norovirus, Listeria

• may cause: nausea, dirrahead, or serious illnesses

What is a foodborne infection? 

• Pathogen grows in the body (Salmonella, E. coli, Listeria, monocytogens, and all viruses & parasites). 

• Grwoth in the food may not be necessary to cause illness. 

• when you ingest live microorganisms that multiply in your body → illness. 

What is a foodborne intoxication?

• Toxins formed in food (Staphylococcus, Botulinum, Bacillus cereus)

• cause illness when consumed

• consuming toxins that are produced by microorganisms in contamined food → illness.

Ways of controlling biological hazards 

• destroy microbes with heat or chemicals 

• prevent contaminzation with hygiene and sanitation 

• control growth via pH, temperature, water activity 

What are chemical hazards

• Naturally occuring: Aflextoxins, allergens

• Added: food colorants, preservatives

• Contaminants: pesticides, heavy metals

How are food allergies a chemical hazard?

• Allergies are the body’s immune response to proteins in food.

• Symptoms range from hives to anaphylaxis.

• Avoidance is the best prevention.

What are the major food allergens? 

• Milk, eggs, fish, shellfish, tree nuts (almonds, pecans, walnuts), peanuts, wheat, soybeans, sesame. 

• they cause over 90% of food allergic reactions. 

• best to avoid altogether

What are the heavy metals that can accumlate in food? 

• Arsenic, Cadmium, Chromium, Lead, Mercury

What are the ways of controlling chemical hazards?

• supply-chain controls

• sanitation controls

• allergen controls

• process controls

What are some physical hazards?

• objects that are not meant to be food that get into it

  • metal, glass, pits, wood chips, or plastic fragments (etc.)

• prevented thru inspection & maintenance.

What are GMPs 

Good manufacturing practices 

• essential conditions and measures for safe food production 

• focus on cleanliness and hygiene 

What are some key components of GMPs?

• personnel

• plant & grounds

• sanitary operations

• sanitary facilities and controls

• equipment and utensils

• processes and controls

• warehousing and distribution

• defect action levels

What are HACCP?

Hazard analysis and critical control points

• international preventive system to manage all 3 catergoies of risk

• ensures food safety from harvest to consumption

What are the 7 principles of HACCP? 

1. conduct hazard analysis 

2. determine the ccps 

3. establish critical limits 

4. establish monitoring system for ccps 

5. establish correction actions 

6. establish procedures for verification 

7. estbalish documentation 

12 steps to implement HACCP

1. assemble HACCP team

2. describe product

3. identify intended use

4. construct flow diagram

5. onsite confiramtion of flow diagram

6. list all potential hazards for each step

7. determine the ccps

8. establish critical limits for each ccp

9. establish a monitoring system for each ccp

10. establish corrective actions

11. establish vertification procedures

12. establish documentation & record keeping

Summary of food safety foundations

• food safety: safe processes / practices to prevent illness

• 3 sources of hazard: bio, chem, physical

• key approaches to safe food:

  • food manufactoring practices (GMP)

  • hazard analysis and critical control point (HACCP)

What is microbiology?

The study of organisms too small to see unaided. 

Serves as a foundation for food saftey and quality control.

Types of microbiology organisms

• bacteria 

• yeasts & molds 

• protozoa 

• algae 

• viruses 

• parasites 

subfields of microbio 

• bacteriology

• mycology

• virology

• parasitology

• etc.

First Glimpses 1700-1810

• 1700s: Antonie van Leeuwenhoek

  • observed the first “wee beasties”

• 1810: Nicolas Appert

  • “father of canning” as he developed the first method of canning food in class jars and heating them as to preserve them.

  • created the early link between heat & spoilage control.

first glimspes 1860-1895 

• 1860s: Louis Pasteur 

  • microbes drive fermentation/decay

  • began pasteurization

• 1895: W.T. Sedgewick

  • Inadequate heat caused canned food spoilage

• thermal processing became systematic

what is mold 

• molds are a type of fungus 

• they are mulicellular microorganisms

• they grow in thread-like structures called hyphae 

• they reproduce by forming spores 

differences between food, bad, and toxic mold

• beneifical mold:

  • used in cheese (blue cheese, brie)

  • produce antibiotics (penicillin)

• harmful molds:

  • cause widespread food spoilage

• mycotoxins:

  • some molds produce toxic compounds (aflatoxins in grains/nuts that cause illness).

what are yeasts 

• single celled fungi, larger than bacteria 

• reproduce by budding 

• many are facultative anaerobes, fermenting sugars to alcohol and CO2 

  • found commonly on fruits and in soil 

what are some ways of using beneficial yeasts?

yeasts are essential for many fermented food and beverages industries.

• baking: saccharyomyces cerevisiae makes bread rise

• brewing: saccharomyces cerevisiae ferments beer

  • winemaking: yeasts converts grape sugars into wine

what are viruses?

• extremely small, non-cellular infectious agents

• composed of genetic material (DNA or RNA) in a protein coat

• obligated intracellular parasites must infect living cells to reproduce

• food acts as a vehicle of transmission, not a place of growth

what are parasites? 

• organisms that live on or in a host, benefiting at the host’s expense 

• foodborne parasites: 

  • protoxoa (microscopic)

  • worms (larger)

• many have complex life cycles, often including multiple hosts

common foodborne parasites 

transmitted thru raw/undercooked meat, contaminated produce, or water 

• toxoplasma gondii (protoxoan) 

  • found in raw, undercooked meat, cat feces

• Trichinella spiralis (roundworm)

  • undercooked pork, wild game

• Cryptosporidium & cyclospora (protozoa)

  • contaminated water, fresh produce (berries, basil)

what are bacteria

• single celled prokaryotic microogrnaisms

  • lack membrane & no nucleus

• found in every environment, including food

• shapes:

  • cocci (sphere)

  • bacilli (rod)

  • spirilla (spiral)

  • although shapes can give clues, metabolic and genetics tests are key for precise ID of bacteria. 

• reproduction: binary fission (splitting in 2)

what are good bacteria 

• essential for fermented foods (yogurt, cheese, pickles) 

• Probiotics support gut health 

what are bad/harmful bacteria 

• cause foodborne illnesses 

• ex: Salmonella, E. coli, Listeria, Staphylococcus auerus 

• Clostridium perfringens 

how does microbial growth relate to food science

• microbes multiply fast under right conditions

• primary reproduce by binary fission: splitting in 2

• we want to slow, stop, or steer that growth

  • do this by changing food & its environment

what are the different phrases of the bacteria growth curve? 

• lag phrase

  • microbes adjust, no visible growth

• log phrase

  • rapid doubling = highest risks

• stationary phrase

  • nutrients drop, waste rises

• death

what are intrinsic factors that drives bacteria growth? 

• Water activity 

  • Lower Aw limits microbial growth

• pH

  • lower pH inhibits more microbes

• nutrients

  • availability of energy, nitrogen, vitamins, and minerals to sustain microbes.

• physical structures

  • intact skins/shells protect from microbes

  • damage invites microbes

what are some extrinsic factors that drives microbial growth? 

environmental conditions surrounding the food

• temperature 

  • cold slows growth, heat kills growth.

• relative humidity (RH)

  • high RH can encourage growth

  • food surface water activity

• gaseous atmosphere

  • CO2 or N2 can inhibit or favor certain microbial growth.

microbiology I lecture takeaways

• food microbio: the study of living cells that are too small to be seen with the naked eye

• beneficial and pathogenic microoganisms

  • bacteria & viruses most implicated in food quality issues

• growth of microorganisms is facilitated by optimum conditions of nutrients, pH, water activity, food composition, temperature, etc.

Escherichia coli (E. coli)

• common in animal & human intestines

• most strains are harmless and part of a healthy gut microbiome

• some pathogentic strains cause severe illness

4 types of E. coli in food safety

• Enteropathogenic E. coli (EPEC)

• Enteroinvasive E. coli (EIEC)

• Enterotoxigenic E. coli (ETEC)

• Enterohemorrhagic E. coli (EHEC)

dangers of E. coli O157:H7

• EHEC strain identified in 1982 

• found in animals (cattle, sheep) without causing them disease 

• sources: undercooked ground beef, unpasteurized dairy, contaminated produce 

• can cause Hemolytic Uremic Syndrome (HUS)

  • severe in children & elderly

What is Clostridium botulinum

• Gram-positive, anaerobic bacterium 

• forms highly resistant spores 

  • Spores are much harder to kill with heat than vegetative cells. 

• produces one of the most potent neuotoxicns: botulinum toxin 

  • botulism: severe paralytic illness (rare)

• source: improperly home-canned foods (low acid), honey (infant botulism)

• Symptoms: double vision, drooping eyelids, difficulty speaking & swallowing, muscle weakness

What is Salmonella? 

• Gram-negative, facultative anaerobic rod, relatively heat-resistant for a non-spore former, 

• has over 2300 antigenic types, only ~200 cause human illness. 

• syndromes: nontyphoidal salmonellosis (gastroenteritis), and typhoid fever. 

• can survive outside the host for considerable periods 

Salmonella in the food chain 

• common sources

  • raw poultry & eggs, raw milk, raw beef, unwashed fruits, alfalfa sprouts, reptile pets

• transmission

  • inadequate cooking, cross-contamination, and use of contaminated raw ingredients

• prevention

  • proper thermal processing

    • pestueriziation, thorough cooking

  • preventing cross-contamination

  • good hygiene in food handling

What is Listeria monocytogenes

• Shape: gram-positive rod 

  • unique ability to grow at refrigerated temperatures (psychotrophic)

• Found a lot in nature

  • soil, water, sewage, and raw foods (meats, milk, vegetables)

• Human pathogens: can exist in animals & humans without causing disease

• significant impact: approximately 2500 cases and 500 deaths annually in the U.S.

What is Listeriosis 

• symptons: varies. 

  • ranges from influenza-like illness to gastrointestinal symptoms to severe manifestations

    • septicemia (blood infection), meningitis (inflammation of the brain & spinal cord), encephalitis (brain inflammation)

• targetted groups:

  • pregnant women, the elderly, and those with compromised immune systems

• prevention:

  • long incubation (7-60 days)

What is Campylobacter jejuni

• shape: gram-negative, curved, motile rod 

• requires a specific low-O2 environment (3-5% O2) 

• relatively sensitive to drying, heating, disinfectants, and high O2 levels 

• leading cause of bacterial diarrheal illness globally 

• Symptoms: 

  • Bloody diarrhea, fever, abdominal pain, nausea, headache

How bacteria cause disease 

• Invasion - directly invade host cells & tissues 

  • Listeria, Salmonella

• Toxin production - bacteria produce harmful toxins that disrupt host functions

• Exotoxins - released by bacteria

  • botulinum toxin from C. botulinum

• Endotoxins - part of the bacterial cell wall, released upon cell death

  • Gram-negative bacteria like E. coli

• Adherence - ability to stick to host cells & resist removal

Bacterial transmisison routes in food systems 

• primary route - oral ingestion of contaminted food/water 

• human - infected food handlers, fecal-oral spread 

  • Shigella

• Animal - inestinal tracts of farm animals

  • Salmonella, E. coli O157:H7, Campylobacter

• Environmental - soil, water, processing environments

  • Listeria

• Cross-contamination - transfer of bacteria from 1 surface to another

High risk foods for bacterial growth

foods that commonly contain pathogenic bacteria AND support their growth

• raw meals (poultry, beef, pork)

• raw eggs

• spouted seeds (alfalfa sprouts)

• lightly cooked foods

• soft cheeses & unpasteurized dairy products

• raw fruits & vegetables not washed thoroughly

• foods mishandled after preparation or cooking

preventing foodborne bacterial illness 

• clean - wash hands, surfaces, and produce thoroughly 

• separate - prevent cross-contamination between raw & ready-to-eat foods. 

• cook - cook foods to a safe internal temp 

• chill - refrigerate perishable foods promptly and properly

Why heat foods? 

• inactivate pathogens & enzymes 

• reduce spoilage organisms 

• enable shelf stability without recontamination 

What is heat transfer?

• Conduction and convection dominate in food systems 

• process design revolves around the cold spot 

• balance safety targets with quality retention 

What is conduction (solid → solid)

• direct heat through solids 

• key variables

  • thermal conductivity (k) 

  • thickness (x)

  • area (x)

  • change in temp

• ex: metal plate heat flow

What is thermal conductivity 

the quantity of heat a given material of unit area of cross section can transfer under a unit temperature gradient in the direction of heat flow 

Equation for conduction heat transfer 

q = (k)(A)(T1-T2)/L 

k = thermal conducitivity 

A = area perpendicular to the heat flow 

L = thickness of the material 

What is Convection (surface → fluid)

• heat carried by moving fluids

• variables:

  • heat transfer coefficient (h)

  • surface area

  • change in temperature

What os the heat transfer coefficient

Also called convectire, is the quantity of heat transferred across a unit surface area to a fluid when a unit temperature gradient exists between the surface and the fluid.

Equation for heat convection 

q = (h)(a)(Ts - T) 

Ts = surface temperature 

T (weird symbol) = teperature at other point away from the surface 

Conduction vs Convection Heating

• Conduction - slower, more uniform heating

• Convection - faster, more efficient heating (often with agitation)

What to consider when choosing the right thermal process?

• consider pH, product state, target microbe, cold spot, shelf-life goal

• low-acid (pH > 4.5) typically requires more severe treatment

what are the 3 thermal process types 

1. blanching - product quality 

2. pasteurization - product safety 

3. sterilization (>100 °C) - product safety 

What is blanching

• purpose - rapid heating of veggies, fruits 

• use - often precedes drying, freezing, canning 

• mechanism - inactivates enzymes, destroys surface microorganisms 

pastruization basics 

• mild heat to reduce pathogens 

• refrigeration needed for many low-acid foods 

• extends shelf-life with minimal quality loss 

• temperature applid (55 C - 100 C)