Food Science - Test 3 Flashcards
Ancient Greek physician whom some have called the “father of medicine”
Hippocrates
- Long tradition of believing that health is dependent on food
- Particularly the maintenance of a population of beneficial bacteria is important
- established foundation to promote research on bifidobacteria
Japan
- Foods that contain functional substances which affect the physiological function and biological activities of the body
- Food that claim if used in the daily diet, one can hope for a specified health benefit
- Foods that must be evaluated individually and approved by the government
Foods of Specific Health Uses (FOSHU)
- Kellogg USA initiated the first health claim for the linkages between fiber consumption and reductions of colon cancer in the late 1980s
- Endorsed by the American Cancer Society
Arrival of Functional Foods in the USA
- A chemical that an organism needs to live and grow or a substance used in an organisms’ metabolism which must be taken from its environment
- Humans require macro and micro to thrive
- There are other components in food, but recommended intake and function haven’t yet been fully established
Nutrient
foods and food components that provide a health benefit beyond basic nutrition
Functional Foods
- Conventional Foods
- Fortified, Enriched, or Enhanced Foods
- Dietary Supplements
Types of Functional Foods
- Containing naturally occurring bioactive compounds
Examples: - Dietary fiber to promote digestive regularity
- Beta-glucan in oat bran to lower blood cholesterol
Conventional Foods
- Foods that must be modified by enrichment, in terms of the amount, type, or nature of the bioactive substances
Example: - Spreads containing added phytosterols
Fortified, Enriched, or Enhanced Foods
- Synthesized food ingredients
Example: - Specialized carbohydrates intended to feed microorganisms in the gut
Dietary Supplement
- Omega-3 Fatty Acids
- Phytosterols
- Folate
- Flavonoids
- Probiotics/Prebiotics
- Botanicals
- Dietary Fiber
- Vitamin E
- Carotenoids
- Minerals
- Bioactive Peptides
- Specialty - Soy, Flax
- Antioxidants - Phytochemicals
Bioactives
- mackerel
- lake trout
- herring
- sardines
- albacore tuna
- salmon
Fish High in Omega-3 Fatty Acid
- cardiovascular mortality
- heart attack
- sudden death
Omega-3 FA in the diet is associated with the reduction of…
On Sept 8, 2004 – the FDA approved the proposed
claim of reduced risk of coronary heart disease (CHD)
on conventional foods that contain eicosapentaenoic
(EPA) & docosahexaenoic (DHA) omega-3 fatty acids
- Claim states the research supports the claim but isn’t fully conclusive
Qualified Health Claim of Omega-3 FA
- Shelf-life consistent with life of food
- No negative sensory impact
- Appropriate cost per serving
- Oil quality remains unchanged
- Easy to formulate in manufacturing
- Bioavailability
- GRAS
- Consumers are ready to accept
- Food companies are ready to accept
Requirements for success in food
- Live microorganisms that exert health
benefits beyond inherent basic nutrition upon
ingestion - “Friendly Microbes” that manipulate the
microbial environment
Probiotics
- special nutrients for the microbes (but
NOT for the human host) - mainly carbohydrate sources
Prebiotics
- Lactobacilli (Small Intestine)
- Bifidobacteria (Large Intestine)
Families of Lactic Bacteria
- Act like a shield and mask receptor sites for pathogenic bacteria
- Act like a shield and mask receptor sites for enterotoxinogen pathogens
- Adhere to intestinal cells and protect them against pathogenic bacteria
Lactic Acid Bacteria
- vitally important for the building of human cell membranes and the production of hormones
- Too high concentration may lead to an increased risk of CVD
- A 1% total blood reduction is associated with 2.7% reduction in CVD risk
Cholesterol
- Naturally occurring lipid-like compounds found in cells and membranes of oil-producing plants, grains, nuts, and trees
- Consumed daily at 0.2 to 0.3 grams in a healthy diet
Phytosterols
- reduce cholesterol uptake
Plant Sterols
- acts as phytoprotectants
Antioxidants in Plants
- protect lipids from oxidation
- may also help preserve color
Antioxidants in Foods
- may provide activity in vivo
- they have a solid scientific track record for positive effects on heart health
Antioxidants in Humans and Animals
- juice may help to slow down the progress of prostate cancer, research suggests
- packed with healthy antioxidants (soluble polyphenols, tannins & anthocyanins) and anti- inflammatory agents
- An Israeli study showed that the juice has anti-atherosclerotic properties; i.e., it slowed down cholesterol oxidation by almost half
Pomegranates
- Adulteration of Food
- Misbranding of Food
- False Advertising
Major Food Safety Problems in the Food Industry
- prevented the manufacture, sale, or transportation
of adulterated or misbranded foods, drugs, medicines,
and liquors
1906 Pure Food and Drug Act
- prohibited
the sale of adulterated or misbranded meat and meat
products for food and ensured that meat and meat
products were slaughtered and processed under sanitary
conditions
1906 Federal Meat Inspection Act
- contained several new provisions, including requiring safe tolerances be set for unavoidable poisonous substances, authorizing standards of identity, quality, and fill-of-container for foods, authorizing factory inspections, and adding the remedy of court injunctions to the previous penalties of seizures and prosecutions
1938 Pure Food and Drug Act (Revised)
- This gave the FDA a way to influence industry actions without mandating specific requirements
“Procedures for the Appraisal of the Toxicity of Chemicals in Food” (1949)
- mandated the inspection of poultry products sold in interstate commerce in response to the expanding market for ready-to-cook and processed poultry products
1957 Poultry Products Inspection Act
- include the Food Additive Amendment, due to consumer concerns about the impact of unknown chemicals in the food they consumed
- ensured the safety of ingredients used in processed foods
1958 Federal Food, Drug, and Cosmetic Act (Amending 1938)
- proclaimed by JFK
- stated that consumers have a right to safety, to be informed, to choose, and to be heard.
1962 Consumer Bill of Rights
- enacted to prevent unfair or deceptive packaging and labeling of many household products, including foods
- requires the identification of the commodity, the name, and location of the manufacturer, packer, or distributor, and the net quantity of contents in terms of weight, measure, or numerical count
1967 Fair Packaging and Labeling Act
- began keeping records on foodborne illness- related deaths in the U.S., marking the beginning of modern data collection on foodborne illness outbreaks
1970 Center for Disease Control
- 1970
- takes over FDA program for setting pesticide tolerances
EPA Established
- created to perform meat and poultry grading and inspection
- later reorganized into Food Safety and Inspection Service (FSIS) in 1981
1977 Food Safety and Quality Service
- requires all packaged foods to bear nutrition labeling and all health claims for foods
1990 Nutrition Labeling and Education Act
- focuses on the prevention and reduction of microbial pathogens on raw products that can cause illness
- was implemented in all FSIS and state-inspected meat and poultry slaughter and processing establishments across the nation, between January 1997 and January 2000
1996 Pathogen Reduction/HACCP Systems Landmark Rule Issued
- Among the major provisions in the Act is an expansion of the FDA’s authority to regulate health and nutrient content claims, and to establish processes related to the food contact substances in new products
1997 Food and Drug Modernization Act (amended)
- enables the FDA to focus on food safety preventative measures rather than being reactionary when an outbreak occurs
- The FDA will have a legislative mandate to require comprehensive, science-based preventive controls across the food supply, including mandatory preventive controls for food facilities, mandatory produce safety standards, and the authority to prevent intentional contamination
- provides the FDA with the necessary tools for inspection, compliance, and incident response
2011 Food Safety Modernization Act
- released by the FDA
- addressing several areas, including traceability, digital technologies, and evolving food business models
Blueprint for New Era of Smarter Food Safety (2020)
- Date Marking
- Product Name
- Net Weight
- Ingredient List
- Nutrition Information
- Usage Instructions
- Manufacturer’s Details
Mandatory Food Labeling
- ## based on a reference amount which is defined in the regulations
Serving Size on Food Labels
- Fat Free = < 0.5 grams fat per serving
- Low-Fat = < 3 grams fat per serving
- Light = product to have 33% fewer calories than a standard reference product
- Other examples include “fresh” , “good source of ___ “ , “Organic” , etc.
Nutritional Claims on Food Labels
- Tells the consumers the ingredients that have been used in manufacturing the food
- Is written in descending order by weight
- Also lists permitted additives
List of Ingredients on Food Labels
- Calories
- Calories from Fat
- Total Fat
- Saturated Fat
- Cholesterol
- Sodium
- Dietary Fiber
- Total Carbs
- Sugar
- Protein
- Vitamin A
- Vitamin C
- Calcium
- Iron
Nutrients that MUST be labeled
- name must be established by law
- customary in the area where the product is sold
- a description of the product
- the picture must not mislead the consumer
Name and Picture on Food Labels
- Use by
- Best before
- Best Before end
- Display until
Types of Date Code
- Used for foods that are microbiologically highly perishable and might harm humans if consumed beyond a certain date
- often used for chilled foods, sandwiches, fresh juices, and fresh meat products
“Use by” Date Code
- written in the form of “Day, Month, Year”
- Used for products that have a shelf life of three months or less
- bread, biscuits, crisps, and sweets
“Best Before” Date Code
- not required by regulations
- used by the store to tell them to remove the product from the shelves by a certain date
“Display Until” Date Code
- Nutrition signposting
- Guideline for daily amounts
- Claims such as ‘no artificial additives’
- Graphical and pictorial information
- Vegetarian/vegan labeling
- May contain (e.g. nuts) labelling
Voluntary Information on Nutrition Labels
- Any foods that has been specially manufactured to meet the allergy- related requirements of a particular group must indicate this clearly on the label
Allergen Information on Food Labels
- must contain “organic farming” label or European Certifying Authority code
Organic Labeling
- Food and Drug Administration (FDA)
- US Department of Agriculture (USDA)
- Federal Trade Commission (FTC)
- Bureau of Alcohol, Tobacco, and Firearms (ATF)
- Environmental Protection Agency (EPA)
Major US Food Regulation Agencies
- Work with industry to interpret regulations
- Help the industry establish control measures
- Make inspections of food plants
- Examine food from interstate shipments
- Issue and enforce regulations on food additives.
- Approve and certify acceptable food colors
- Test for pesticide residues
- Examine imported foods.
- Advise state and local inspection agencies.
- Work with state and local agencies in times of disaster to dispose of contaminated foods.
- Set up “standards of identity” to promote honesty and value of food products
Federal Agencies jobs for Food Regulation
- Determines which food additives are allowed in foods
- Matches the ingredient statement on the label with the ingredients in the products
- Approves processing methods
- Develop Good Manufacturing Practices
- Sets microbial standards
- Develop HACCP for seafood and juice
- Inspects food processing plants
- Has the power to shut down the plant and issue the product recalls of unsafe foods
US Food and Drug Administration
- Regulates all meat plants
- Developed guidelines on the methods of slaughter and handling fresh products
- Inspectors look at every carcass of fresh meat
- Develop HACCP for meat
- Inspects food processing plants and can shut down plants
US Department of Agriculture
- Food Safety and Inspection Service (FSIS)
- Animal, Plant, and Health Inspection Service (APHIS)
- Grain Inspection, Packers and Stockyard Administration (GIPSA)
- Agricultural Marketing Service (AMS)
US Agencies focused on the Meat Industry
- Regulates pesticides in foods
- If a pesticide is concentrated in processed food, then it is considered a food additive and regulated by FDA
US Environmental Protection Agency
- Sends epidemiologists to investigate food–associated outbreaks
- Identify the cause of the outbreak
- Provide guidelines on how future outbreaks can be prevented.
- Maintains a nationwide system of foodborne disease surveillance
- Develops and advocates public health policies to prevent foodborne diseases.
- Conducts research to help prevent foodborne illness
Centers for Disease Control and Prevention (CDC)
- Department of Agriculture
- Department of Health
State Agencies for Food Regulation
- City or County health inspectors (health departments)
- inspect restaurants giving health rating scores
- can shut down a restaurant
Local Agencies for Food Regulation
Laws passed by Congress go into the U.S. Code, which is divided into titles
Statutory Law
These are regulations and practical instructions found in the Code of Federal Regulations (CFR)
Administrative Law
- a scientific discipline describing the safe processes and practices to grow, harvest, store, transport, handle, prepare, and serve food and food ingredients to prevent foodborne illness
Food Safety
- it contains any poisonous or deleterious substances, such as chemical contaminants, which may or ordinarily render it harmful to health
Contaminated Food
- when a person gets sick from eating contaminated food
- symptoms vary from: stomach cramps, nausea, vomiting, diarrhea, and fever (for more serious cases)
Foodborne Illness
- 48 million people get sick from foodborne illnesses each year
- CDC estimates 1/6 Americans will get sick from known or unknown bacteria, viruses, and microbes each year resulting in about 128,000 hospitalizations and ~3000 deaths
US Foodborne Illness Stats
Any biological, chemical, or physical agent that has the potential to cause illness or injury
Food Safety Hazards
- Food poisoning can be caused by pests and microorganisms
- Poisoning can occur when pathogens are consumed which then grows inside the consumer
- can also occur by consumption of poison produced when the pathogen grows in the food
Biological Food Safety Hazards
- Bacteria
- Viruses
- Protozoa
- Yeasts
- Molds
- Prions
Potential Biological Hazards
- most common cause of food poisoning
- symptoms and severity can vary
Bacteria and Viruses
- Salmonella
- Norovirus
- Campylobacter
- E. Coli
- Listeria
- Clostridium perfringens
Bacteria and Viruses that caused the most illnesses, hospitalizations, and deaths
- Pathogen invades the body after consumption of contaminated food
- Growth in the food may not be necessary to cause illness
EX: Pathogenic E. Coli, Salmonella, Listeria monocytogenes, and all viruses and parasites
Foodborne Infection
- Pathogen growth in the food produces a toxin that causes illness when consumed
- No growth in food = No toxin = No illness
EX: Staphylococcus aureus, Clostridium botulinum, Bacillus cereus
Foodborne Intoxication
- Prevent contamination
- destroy them
- Control growth
Control Methods for Bacteria
- Techniques include: heat, acid, antimicrobial chemicals, irradiation, ultrasound, pulsed light, high pressure
- time, temperature and food composition all influence the rate at which they are killed
- models can predict inactivation
Destroying Bacteria
Their growth can be controlled if we know their growth factors, including:
- Food
- Temperature
- pH
- water activity
- proper atmosphere
- microbial competition
- preservatives
Controlling the Growth of Bacteria
substances that are unintentionally present in foods. They can also be naturally present in foods but are at harmful levels for human consumption
Chemical Food Safety Hazards
- depends on the chemical and the level in the food
- some may cause immediate or near-term illnesses
- some may cause long term effects
Health Effects of Chemical Hazards
Naturally Occurring:
- mould toxins
- toxic shellfish, algal blooms, ciguatera poisoning from tropical fish
- allergic reactions to food
Used in Formulation:
- food additives
- color additives
- preservatives
Unintentionally Present:
- ground breakers, wetting agents, algal treatments, fertilizers, heavy metals
- pesticides, weedicides, fungicides
- antibiotics, hormones, dips, drenches
- cleaning, pest control, maintenance chemicals
- food ingredients
Chemical Hazards Examples
- An adverse response by the body to foods containing allergenic proteins
- A miniscule amount of protein/allergen can trigger different symptoms in different individuals
- Food allergy symptoms are unpredictable and vary from mild reactions to death
Food Allergy Chemical Hazard
- Mouth: swelling and tingling of lips, mouth or tongue
- GI: cramping, vomiting, diarrhea
- skin: hives, eczema
- airway: wheezing, coughing, swelling of the throat
- cardiovascular: loss of blood pressure
- anaphylaxis: most dangerous, life threatening
Food Allergy Symptoms
- Milk
- Egg
- Peanut
- Tree nuts
- Fish
- Crustacean shellfish
- wheat
- soy
(responsible for 90% of food allergies)
Major Food Allergens
- complete avoidance is the primary treatment
- this requires:
- individual responsibility to avoid the food and prepare just in case
- those who supply food should provide accurate info about said food
Food Allergy Treatment
- must be registered with the EPA
- must be used according to the label instructions
- regulatory programs may address: applicator licensure, usage instructions, official monitoring of residues
- high compliance for US operations
- imported product compliance rates vary
Pesticides
Arsenic, Lead, and Mercury
- may accumulate in plants or fish
Heavy Metals Examples
- supply chain controls
- sanitation controls
- allergen controls
- process controls
Control of Potential Chemical Hazards
- objects that are not part of food, never meant to be food, but somehow got into the food (foreign material)
Physical Food Safety Hazards
- good manufacturing practices
- hazard analysis and critical control points
Approaches to Ensuring Food Safety
- All practices regarding the conditions and measures necessary to ensure the safety and suitability of food at all stages of the food chain
Good Manufacturing Practices
- personnel
- plant and grounds
- sanitary operations
- sanitary facilities and controls
- equipment and utensils
- processes and controls
- warehouse and distribution
- defect action levels
Components of GMPs
- An internationally accepted methodology to reduce and manage risk
- A preventive system for food safety that addresses chemical, physical and biological risk
- Treats the production of food as a total, continuous system, assuring food safety from harvest to Consumption
- 7 Principles & 12 Steps
Hazard Analysis and Critical Control Points
- Conduct a hazard analysis
- Determine the CCPs
- Establish critical limits
- Establish a system to monitor the CCPs
- Establish the corrective actions to be taken when monitoring indicates that a particular CCP is not in control
- Establish procedures for verification to confirm that the HACCP System is working effectively
- Establish documentation concerning all procedures and records appropriate to these principles and their application
HACCP Principles
- Assemble HACCP team
- Describe product
- Identify intended use
- Construct flow diagram
- Onsite confirmation of flow diagram
- List all potential hazards associated with each step, conduct a hazard analysis & consider any measures to control identified hazards
- Determine the CCPs
- Establish Critical Limits for each CCP
- Establish a monitoring system for each CCP
- Establish Corrective Actions
- Establish Verification Procedures
- Establish documentation & Record Keeping
12 Steps of HACCP
- the study of organisms that are too small to be seen with the naked eye
EX: bacteria, fungi, protozoa, algae, viruses, parasites
Microbiology
Study of Bacteria
Bacteriology
Study of Fungi
Mycology
Study of Protozoa
Protozoology
Study of Algae
Phycology
Study of Viruses
Virology
Study of Parasites
Parasitology
- prokaryotic
- eukaryotic
Types of Biological Cells
cells with no
internal membrane-bound structures
- includes: bacteria
Prokaryotic Cells
cells with internal
membrane-bound structures
- includes: protozoans, fungi, algae, animals and plants
Eukaryotic Cells
- genus
- species
- sub-species
Binomial Names
- Christian Gram developed the Gram stain in 1884
- Gram used the stain to examine cocci in the lungs of dead patients
- 4 steps were involved: crystal violet (purple), iodine, alcohol, safranin (red)
Taxonomy of Bacteria
- The cell wall of Gram-positive bacteria is composed of thick layers peptidoglycan.
- In the gram staining procedure, Gram-positive cells retain the purple-colored stain
Gram-positive Bacteria
- The cell wall of Gram-negative bacteria is composed of thin layers of peptidoglycan.
- In the Gram staining procedure, Gram-negative cells do not retain the purple-colored stain
Gram-negative Bacteria
- Intrinsic Factors
- Extrinsic Factors
Factors Affecting Growth and Survival
of Microorganisms in foods
- Structure of food
- Composition of food
- Water activity
- pH
Intrinsic Factors of Microorganisms
- temperature
- relative humidity
- gaseous atmosphere
Extrinsic Factors of Microorganisms
- controlled atmosphere storage
- vacuum packaging
- Modified atmosphere packaging
Modified atmosphere packaging and storage
- Cocci (Staphylococci, streptococci, diplococci)
- Rods (Bacilli, streptobacilli, coccobacilli)
- Spiral (vibrio, spirilla, spirochaetes)
Shapes of Bacteria
- gram-negative rod
- Common microbe in intestinal tracts
- Found in warm-blooded animals, humans
- Also found in some flies
- Pathogenic strains cause diarrhea and other illness
- Categorized according to syndromes, reaction to the immune system, and mechanisms for illness
- Contaminated raw vegetables are one vehicle
Escherichia coli (E.coli)
- Enteropathogenic E. coli (EPEC)
- Enteroinvasive E. coli (EIEC)
- Enterotoxigenic E. coli (ETEC)
- Enterohemorrhagic E. coli (EHEC)
Types of E. coli
- First recognized as human pathogen in 1982
- Causes foodborne infection
- Most outbreaks associated with undercooked
ground beef and dairy products - May cause hemolytic uremic syndrome
- Naturally exists in animals without causing disease
- Cattle, sheep, deer, dogs, cats, and other animals
- Outbreaks linked to lettuce, unpasteurized apple cider, radish sprouts, and alfalfa sprouts
- Can grow on fresh produce
- Minimally processed cantaloupe and watermelon cubes, shredded lettuce, and sliced cucumbers
E. coli O157:H7
- Gram-negative facultative anaerobic rod
- Heat inactivation varies with strain but is somewhat heat resistant for a non-spore former
- Can remain viable outside of a primary reservoir for a considerable time
- More than 2300 antigenic types (200 types cause human illness)
- associated primarily with poultry
- Killed by proper thermal process
- Relatively stress resistant
Salmonella
- Gram-positive rod
- Very common
- Relatively hardy
- Will grow at refrigeration temperatures
- Humans may be intestinal carriers
- up to 15 different nonpathogenic species
- Widely distributed in nature
- Can exist in animals without causing disease
- found in raw foods (meat, milk, vegetables)
- Virulent pathogen
Listeria monocytogenes
Symptoms include:
- Potential incubation time 7-60 d
- Influenza-like symptoms
- Gastrointestinal symptoms may occur
Manifestations include:
- Septicemia
- Meningitis (meningoencephalitis)
- Encephalitis
- Intrauterine or cervical infections in
pregnant women which may result in
spontaneous abortion
Listeriosis
- Gram negative curved, motile rod.
- Microaerophilic (requires 3-5% oxygen and 2-10% carbon dioxide)
- Relatively sensitive to environmental stresses
Campylobacter jejuni
Symptoms include:
- Diarrhea
- fever
- abdominal pain
- nausea
- headache and muscle pain
- Complications are relatively rare
- 1-2 million cases/year
- Pathological effect
- Mechanism is still not fully known
Campylobacteriosis
- Excreted in feces by infected individuals
- No growth in or on foods
- Raw produce as vehicles
- May persist for weeks or months on crops or in soils
Examples: - Hepatitis A on lettuce, raspberries
Viruses as Microbial Hazards
- Life cycle requires animal or human as host
- Contamination via sewage or irrigation water
- Common in regions with poor hygienic conditions
Examples:
- Cryptosporidium, apple juice
- Cyclospora, imported raspberries, basil
Parasites as Microbial Hazards
- can be transmitted to plants and fresh fruits and vegetables by insects, tractors, equipment, clippers, and people
- can cause plant and animal diseases.
- By preventing transmission, plant diseases are decreased and produce safety is increased
Virus Transmission
- An infected person can spread the disease to others well before the symptoms are present.
- It is primarily transmitted by person-to-person contact through fecal contamination but can also be spread through food and water.
- Proper sanitation on the farm and farm workers who practice proper hygiene can greatly reduce the risk
Hepatitis A
- are a diverse group of viruses in the family Caliciviridae
- currently 5 groups are recognized, but only 3 can affect humans
- > 25 different types have been found in these groups
- people can get infected multiple times throughout their life
- possible to build immunity, but might not last forever
- infected people shed billions of viruses in their stool and vomit
Noroviruses
- Living organisms that need a host to survive
- Larger than bacteria, yet still microscopic
- Typically passed to humans through animal host (cows, chickens, pigs, fish)
Parasites
- Unicellular microorganisms, that lack cell wall and are usually motile
- Many protozoa that are pathogenic to humans, exists as cysts in the environment and require an animal intestinal tract to multiply.
- Human diseases caused by this are often the result of fecal contamination of water or produce
Protozoa
Found naturally in air, soil, plants, water, and some food.
Examples: mold, yeast, mushrooms
Fungi
- Responsible for spoilage of food
- Results in odors, discoloration, and off flavors - alcohol scent or flavor
- Prefer to grow in and on acidic food with low water activity.
- Aflatoxin - produced by molds and can cause liver disease in peanut products, tree nuts.
- Throw away molded foods to prevent illness
Mold
- Ability to spoil food rapidly.
- Produces carbon dioxide and alcohol.
- May appear slimy, produce bubbles, and have a pink discoloration.
- Food spoiled by yeast should be discarded.
- Found in jellies, jams, honey, syrups, and fruit juice
Yeast
- the controlled use of heat to increase, or reduce (depending on circumstances) the rates of reactions in foods; in particular, it is the use of heat to inactivate or destroy pathogenic microorganisms in foods
Main Objectives:
- Make the food product safe & shelf-stable
- Reduce the number of microorganisms of public health concern to a statistically small level
- Package the food in an environment to prevent recontamination and suppress the growth & activity of spoilage microorganisms
Thermal Processing
- conduction
- convection
- radiation
Modes of Heat Transfer
- Thermal conductivity (k) is 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
q = kA(delta)T / x
Conduction Heat Transfer
- Heat transfer coefficient (h) (convective) 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
q = hA(delta)T
Convection Heat Transfer
- Physio-chemical properties of food
- Target microorganism
- Location of cold spot
- shelf-life requirement
Before Deciding Thermal Process…
- Blanching
- Sterilization
- Pasteurization
Types of Thermal Processing
- It involves rapidly heating vegetables and fruits to a predetermined temperature and maintaining them for a specified amount of time, typically 1 to less than 10 minutes
- Usually prior to food processes such as drying, freezing, frying, and canning
- Inactivates the enzymes and destroys microorganisms that might contaminate raw vegetables and fruits
- Blanching medium may include water, steam, hot gas, and microwave
Blanching
- Mild heat treatment
- Temperature applied (55oC – 100oC)
- Destruction of pathogenic microorganims
- Not high enough to destroy all spoilage bacterial spores
- Product refrigerated to control spoilage
- Temporary shelf-life extension
- For high acid products same treatment can achieve shelf stability since most spoilage occurs through vegetative bacteria, yeasts and molds which are killed by adequate pasteurization treatment
Pasteurization
- Every particle (e.g. milk) must be heated to at least 63°C and held for at least 30 minutes.
- Low Temperature Long Time (LTLT)/Vat treatment
- Traditional; not used commercially these days
Batch (holding) Process
- Every particle (e.g. milk) must be heated to at least 72°C and held for at least 15 seconds
- High Temperature Short Time (HTST) treatment or Flash pasteurization
- Less nutritional and sensory damage
Continuous Process
- Application of heat for the purpose of shelf life extension & promotion of safety
- More severe heat treatment
- Long term preservation
- “Misnomer” because product not sterile
- “Commercially Sterile”
- Temperature applied of 100-150oC, reference T=121oC
- Associated with hermetically sealed packaging & storage at below 30oC (usually at room temperature)
- Container environment will prevent the growth of microorganisms of public health concern & spoilage type
Commercial Sterilization
- Product is packaged before heating
- Solid product (meat, seafood, vegetables)
- Prolonged heating in hermetically sealed containers, such as cans or retortable pouches
- Renders the contents of the container sterile
- Long-term microbiological stability for non-dried foods
- High temperature: 116-121 °C (240-250 °F)
- Long time (50-90 min)
- Uses pressure vessels (retorts)
- Substantial changes in nutritive and sensory characteristics
Canning (retorting)
- Product and package are sterilized separately
- Liquid product (milk, juice, soup)
Aseptic Processing (ultra high temp UHT processing)
- The amount of heat required to destroy microorganisms in a product can be determined through thermal death time
(TDT) tests. - TDT tests are conducted by thermo- bacteriologists in a laboratory.
- Very few food processing establishments have the facilities to conduct TDT tests on-site
Thermal Resistance of Microorganisms
- Closed, pressurized vessel used for heating foods sealed in containers.
- Pressurized system: Temperature much higher than boiling water
- Needs heating medium (hot water, steam, steam-air mixture)
Retort
Some retort systems provide overpressure during processing and cooling to maintain containers’ integrity and counterbalance the buildup of pressure inside them
Overpressure Retort Processing
- Steam carries considerable heat or “stored energy” (latent heat) that results from conversion of water to vapor
- When steam condenses, as occurs in the retort, this heat is given up and transferred to the containers
- In other words, the steam is able to carry an “extra load” of heat from the boiler to the retort – a task that hot air is not able to accomplish
- This important feature of steam can be demonstrated by comparing the effect of placing one’s hand in a dry heat oven at 250°F (121°C) and live steam at 212°F (100°C)
Retort with Steam
Containers do not move during the thermal process
- can be vertical or horizontal
Still Retort
- Improving heat transfer by enhanced convection
- Reducing heating time
- Improving quality
Agitating Retorts
Application of the thermal process in a continuous system using rapid heating to ultra-high temperatures (UHT, 140-150°C) for a short time (4-6 seconds), followed by immediate cooling
- Successful aseptic processing cannot be assumed unless the cleaned processing system and filler have been adequately sterilized prior to starting production
- The primary objective of conventional canning and aseptic processing and packaging is to produce a commercially sterile product in a hermetically sealed, commercially sterile package
Aseptic Processing
UHT food is aseptically placed
into pre-sterilized containers and hermetically
sealed
- only practical for liquid or fluid products
Aseptic Packaging
- A pumpable product
- Equipment that can be sterilized
- Sterile product
- Sterile packages
- Sterile environment
- Monitoring, recording, and controlling critical factors
- Proper handling of finished packages to maintain container integrity
Requirements of Aseptic Processing
- heating process
- heating medium
- heating conditions
- product type
- container
Heating Profile depends on
- Removing the oxygen from the package
- Controlling the pH
- Giving adequate heat treatment
- Controlling the storage temperature
- Foods are packaged in hermetically sealed containers to prevent recontamination
Success of Thermal Process depends on
Flip flop rotation of dipole molecules like water
Dipole Rotation
Back and forth vibration of ionic salts like sodium chloride
Ionic Polarization
- Dielectric constant, loss factor
- Ability of the material to absorb and dissipate energy
- Depend on product composition, temperature MW properties
Dielectric Properties
- Volumetric heating
- Reduced processing time
- Instantaneous control and clean process
- Selective energy absorption by polar molecules (drying applications)
- Can be combined with other energy sources and chemicals
Advantages to Microwave Processing
- High Pressure Processing (HPP)
- Light (UV, pulsed light)
- Gases (ozone, chorine dioxide)
- Pulsed electric fields (PEF)
- Ionized Radiation (gamma irradiation, x-ray, electron beam)
Non-thermal Processing Methods
Application of pressure is instantaneous and uniform through out the sample
Iso-static Principle (physical)
- Reactions resulting in a volume change are influenced by high pressure applications
- Reactions resulting in a volume decrease are accelerated with the application of HP
Le Chateliers’s Principle (chemical)
- pasteurization
- sterilization
- texture modification
- functional changes
- specialty processes
HPP Application Areas
- Process related
- product related
- equipment related
Factors affecting HPP
