FMLec M3 | Shelf-life indicators

_ is the time between the production of the product and the point at which the product becomes unacceptable to consumers

Shelf life

Explain microbiological limits for end of shelf life

*product = typical shelf life

bsp cfc

• Bread = up to 1 week at ambient

• Sauces & dressings = 1-2 yrs at ambient

• Pickles = 2-3 yrs at ambient

• Chilled food = Up to 4 months at 0-8 C

• Frozen food = 12-18 months in freezer cabinets

• Canned food

  • Unlacquered = 12-18 months

  • Lacquered = 2-4 yrs

_ is a systematic way of determining how long a product can be kept under specific storage conditions, while still maintaining its quality

Shelf life testing services

Purposes of shelf life testing services

• Compliance to regulatory standards

• Product registration

• Establishing mode of deterioration

• Establishing suitability of packaging

3 analyses done in shelf life testing

mps

• Microbiological

• Physiological

• Sensory

Enumerate & explain 2 approaches to shelf-life determination

• Direct shelf life determination & monitoring

  • Applicable for products with short shelf lives

    • Batches of samples are taken at specified stages of product development

    • Samples are stored under controlled conditions until quality becomes unacceptable

    • Tests (M, P, S)

• Accelerated shelf life estimation

  • Performed to meet product launch dates

  • Storage temperature is increased to increase ageing process

_ is an approach to shelf life determination that is applicable for products with short shelf lives

Direct shelf life determination & monitoring

Describe process of direct shelf life determination & monitoring

• Batches of samples are taken at specified stages in their product development

• Samples are stored under controlled conditions until quality becomes unacceptable

• Tests (M,P,S)

_ is an approach to shelf life determination where storage temperature is increased to increase ageing process

Accelerated shelf life estimation

Enumerate 3 chemical indicators of spoilage

dpv

• Depletion of glucose (e.g., red meat)

• Production of lactic acid, acetic acid, ethanol (e.g., pork, beef)

• Volatile compounds (e.g., proponol in beef)

Explain 3 analyses making up microbiological determination of shelf life

scp

1. Storage trials

   1. Samples are taken at specified timed intervals and analyzed for:

      1. Total microbial count

      2. Specific spoilage organisms (Pseudomonads, LAB)

   2. Viable count is compared with sensory evaluation

2. Challenge tests

   1. Samples are incubated under conditions that replicate/reproduce large-scale food production & storage period

   2. May be inoculated with target organisms (C. sporogenes)

3. Predictive modelling

   1. Simultaneously predict growth of microorganisms over a range of conditions

   2. Valide the model using published & in-house lab data

Part of microbiological shelf life determination

• Samples are incubated at conditions replicating large-scale food production & storage period

• May be inoculated w/ target organisms (C. sporogenes)

Challenge tests

Part of microbiological shelf life determination

• Samples are taken at timed intervals & analyzed for

  • Total microbial count

  • Specific spoilage organisms (Pseudomonads, LAB)

• Viable count compared with sensory evals

Storage trials

Part of microbiological shelf life determination

• Simultaneously predicts growth of microorganisms over range of conditions

• Validate model with published & in-house data

Predictive modelling

2 aspects to consider in causative agents of disease & associated food vectors

• Indicator organisms

• Foodborne pathogens & agents

The presence or absence of _ provides indirect evidence concerning a particular feature in the history of the sample

Indicator organisms

Indicator organisms can be any _ group of organisms

tpe

taxonomic, physiological, or ecological

T/F: Indicator organisms are used to assess food quality than food hygiene and safety

FALSE

Indicator organisms are used to assess food hygiene and safety, rather than food quality

Enumerate & explain 7 important characteristics of a food safety indicator

eead gpa

• Easily & rapidly detectable

• Easily distinguishable from other members of food flora

• Always present when pathogen of concern is present

• Density correlates with that of pathogen of concern

• Growth requirements & rates should be equal to that of POC

• Persists slightly longer than POC (to prevent false negatives)

• Absent from foods free of POC (to prevent false positives)

Enumerate 4 common indicator organisms

ceeb

• Coliforms

• Enterobacteriaceae

• Enterococci

• Bacteriophages

• _ is an indicator organism that ferments lactose to acid & gas at 35 C, 48 hrs

• Gram-negative, rod-shaped, facultatively anaerobic bacteria

Coliforms

Coliforms are indicators of _

epf

• Enteric pathogens

• Post-processing contamination

• Fecal contamination

Total coliform vs. Fecal coliform vs. E. coli

• Total coliform = general environmental contamination

  • e.g., ekec Escherichia, Klebsiella, Enterobacter, Citrobacter

• Fecal coliform = fecal pollution

  • e.g., E. coli = best indicator of recent fecal contam

  • E. coli O157:H7 = pathogenic strain

_ is the best indicator of fecal contamination

E. coli

Explain multiple tube fermentation technique as coliform test

*35C for 24-48h

1. Presumptive test: to detect possible coliforms via lactose fermentation

   1. Lauryl Sulfate Tryptose Broth (LSTB) broth with Durham tube

   2. (+)= Gas prod + turbid

2. Confirmed test = to confirm if gas production was due to coliforms or not

   1. Brilliant Green Lactose Bile Broth (BGLBB) with Durham tube

   2. (+)= Gas prod

3. Completed test = to confirm E. coli presence

   1. EMBA

   2. (+) colonies w/ dark center & metallic green sheen

Enterobacteriaceae vs. Total vs. Fecal vs. E. coli

• Enterobacteriaceae

  • Gram (-), bacilli, facultative anaerobe

  • Total coliforms + Salmonella & Shigella

• Total coliforms = ekec Escherichia, Klebsiella, Enterobacter, Citrobacter

  • Fecal coliform

    • E. coli

T/F: Salmonella & Shigella are total coliforms

FALSE

Salmonella & Shigella are not total coliforms but are part of Enterobacteriaceae

_ is an indicator of enteric pathogens

Enterobacteriaceae

• part of this group are essey Escherichia, Salmonella, Shigella, Enterobacter, Yersinia

• Gram (-), basilli, facultative anaerobes

• Indicators of enteric pathogens

Enterobacteriaceae

_ is an indicator of fecal contamination in water

Enterococci

_ is an enterococcal species that indicates presence of human & animal feces

Enterococcus faecium

_ is an enterococcal species that indicates presence of human feces

Enterococcus faecalis

_ is an indicator of waterborne viruses and is present in human fecal matter

Bacteriophages

T/F: Bacteriophages are present in human fecal matter

TRUE

_ is an indicator for hygienic quality of frozen, dried, heat-treated food because they are more resistant to drying than coliforms, die more slowly than E. coli, survives better than pathogens, hence their detection may have little consequence

Enterococci

Enterococci is an indicator for hygienic quality of frozen, dried, heat-treated food because they are _

mds

• More resistant to drying than coliforms

• Die more slowly than E. coli

• Survives better than pathogens, thus detection may be of little consequence

Explain plaque assay pipeline

• Create double agar plate by

  • first pouring TSA agar onto an empty plate as bottom agar

  • then creating a mix of E. coli overnight culture + soft agar, then pouring this mix on top of solidified bottom TSA agar

• Pipette 100 uL phage suspension on top of solidifed E. coli + soft agar mix

• Incubate at 36C

• Observed formed plaques (indicative of bacterial cells lysed by viruses)

Enumerate 5 foodborne pathogens & agents

bvptp

• Bacteria

• Viruses

• Parasites

• Toxins

• Prions

Enumerate 15 foodborne bacteria

cam sal e

• Campylobacter

• Salmonella

• E. coli

shi cro vi

• Shigella

• Cronobacter

• Vibrio

bru ye ae

• Brucella

• Yersinia

• Aeromonas

lis sta clo

• Listeria

• Staphylococcus

• Clostridium

bac strep ent

• Bacillus

• Streptococcus

• Enterococcus

Foodborne bacteria

• Gram (-)

• Cause sporadic & self-limiting gastroenteritis

• Raw chicken, beef, milk, mushrooms, rbmm

  clams, hamburger, water, cheese, pork,

  shellfish, eggs, cake icing

Campylobacter

T/F: C. coli cause 80% of Campylobacter self-limiting gastroenteritis, while C. jejuni cause 15%

FALSE

C. coli cause 15% of Campylobacter self-limiting gastroenteritis, while C. jejuni cause 80%

Foodborne bacteria

• Gram (-)

• Cause gei

  • Gastroenteritis =

  • Enteric fever =

  • Invasive systemic disease =

• Raw poultry, meat, eggs, milk and dairy

  products, vegetables, fruits, chocolate,

  coconut, peanuts, fish, shellfish

Salmonella

• Cause gei

  • Gastroenteritis = serovar Enteritidis, Typhi

  • Enteric fever = Typhi, Paratyphi

  • Invasive systemic disease = Choleraesuis

Explain the different types of E. coli & disease they cause

Gram (-)

• EPEC (Enteropathogenic)

  • Infant diarrhea

  • • Raw chicken and beef, fecal-contaminated food or

    water

• ETEC (Enterotoxigenic)

  • Traveler’s diarrhea

  • • Human sewage-contaminated food

    • Infected food handlers

• EIEC (Enteroinvasive)

  • Shigellosis-like

  • Fecal-contaminated food or water, hamburger meat,

    unpasteurized milk

• STEC (Shiga toxin-producing E. coli)

  • Hemorrhagic colitis

  • Hemolytic uremic syndrome (Complication)

    • O157:H7 (Strain of major concern)

    • Ground beef, poultry, apple cider, raw milk,

    vegetables, cantaloupe, hot dogs, mayonnaise, salad

    bar items

T/F: Shigella and EIEC both cause hemorrhagic diarrhea

TRUE

Foodborne bacteria

• Gram (-)

• Cause blood/nonbloody diarrhea

• Salads, raw vegetables, bakery

  products, sandwich fillings, milk,

  and dairy products, poultry

Shigella

Foodborne bacteria

• Gram (-)

• Powdered infant formula, plant-based ingredients, vegetables, salads

• Infants = meningitis, necrotizing enterocolitis

• Elderly = Gastroenteritis, appendicits

Cronobacter

Explain the different types of Vibrio & disease they cause

• V. cholerae = watery diarrhea

  • Seafood, vegetables, cooked rice, ice

• V. parahaemolyticus = watery diarrhea + fever + vomiting

  • Raw or undercooked fish and fishery product

• V. vulnificus = watery diarrhea + blood

  • Seafood, particularly raw oysters

Foodborne bacteria

• Gram (-)

• Sweating, headache, lack of appetite, fatigue, fever (_)

• Raw or unheated processed foods of

  animal origin (e.g. milk, milk products,

  cream, cheese, butter)

Brucella

Foodborne bacteria

• Gram (-)

• Gastroenteritis w/ diarrhea and/or vomiting

• Pork products, cured or uncured, milk and dairy

  products

Yersinia

Foodborne bacteria

• Gram (-)

• Gastroenteritis

• Seafood, snails, drinking water

Aeromonas

Foodborne bacteria

• Gram (-)

• Gastroenteritis

• Freshwater fish, shellfish

Plesiomonas

Foodborne bacteria

• Gram (-)

• Meningitis, sepsis

• Can cross the placental barrier

• Can grow and survive over a wide range of environmental

  conditions (4°C, Low pH, High-salt)

• Soft‐ripened cheese, ground meat, poultry, dairy products,

  sausages, potato salad, chicken, seafood, vegetables

Listeria

Foodborne bacteria

• Gram (+)

• Food poisoning

• Workers handling foods, meat (especially sliced meat) poultry, fish, canned mushrooms, dairy products, prepared salad dressing, ham, salami, bakery items, custards, cheese

Staphylococcus aureus

Foodborne bacteria

Gram (+), endospore-forming (anaerobic), describe 2 types

Clostridium

• C. perfringens (enterotoxins) = food poisoning

  • Meat, chicken gravies, beans,

    seafood

• C. botulinum (neurotoxin) = botulism

  • Improperly canned or

    fermented goods, honey

Neurological condition characterized by weakness or paralysis, reduced muscle tone (hypotonia)

Botulism

Foodborne bacteria

• Gram (+), endospore-forming

• Diarrhea

  • Food infection (not only toxins)

  • Meats, milk, vegetables, and fish

• Emetic toxin/syndrome

  • Food poisoning/food intoxication

  • Rice products, starchy foods (e.g. potato, pasta and cheese products)

Bacillus cereus

• Streptococcus (Gram + cocci) species of concern that is B-hemolytic

• Temperature‐abused milk, ice cream,

  eggs, steamed lobster, ground ham,

  potato salad, egg salad, custard, rice

  pudding, shrimp salad

• Sore throat and scarlet fever

S. pyogenes

Foodborne bacteria

• Gram (+) fecal streptococci

• Meat, sausage, evaporated milk,

  cheese, raw and pasteurized

  milk

• Acute and self-limiting diarrhea

Enterococcus

Foodborne viruses are likely _

phage and animal viruses

In foodborne viruses, food serves as _

• vehicle of transmission

  • Don’t replicate in food/water

  • Numbers don’t increase during transport/processing

  • Low infectious dose (implies that minimal contam → widespread illness)

• _ are environmentally stable, relatively resistant to heat, disinfection, pH changes

• Retains their infectivity over time and within the food matrix

• Human fecal contamination shed in large amounts in

  feces

Foodborne viruses

What are the viruses associated with the ff. foods?

• Salad + fruits = ?

• Salad + shellfish = ?

• Raw shellfish + raw/undercooked pork products = ?

• Fruits + vegetables + clams = ?

• Salad + fruits = Rotavirus

• Salad + shellfish = Norovirus

• Raw shellfish + raw/undercooked pork products = Hepatitis E

• Fruits + vegetables + clams = Hepatitis A

Explain 5 ways thru which viruses get into food supply

fhpaf

• Shellfish contamined with fecal-polluted marine water

• Human sewage pollution of drinking & irrigation water

• RTE & prepared foods contam by poor personal hygiene

• Aerosolization of vomit

• Contact with fomites

_ include eukaryotes such as protozoa and helminths

Parasites

• Protozoa

• Hydrocephalus and blindness in children

• Transplacental infection

• Raw or undercooked meat, vegetables, goat’s milk, food and water contaminated with cat feces

Toxoplasma gondii

• Toxoplasmosis

• Protozoa

• Watery and explosive diarrhea

• Raspberries, lettuce and basil or basil‐containing products

Cyclospora cayetanensis

• Protozoa

• Fever, diarrhea, abdominal pain, anorexia

• Raw milk, drinking water, apple cider

Cryptosporidium parvum

• Beef tapeworm

• Taeniasis

• Raw or undercooked beef

Taenia saginata

• Pork tapeworm

• Taeniasis

• Cysticercosis (larval cyst in the brain, muscle, or other tissues)

• Raw or undercooked pork

Taenia solium

• Helminth

• Nematode (roundworm)

• Nonspecific abdominal stress

• Raw/undercooked fish

Anisakis simplex

Food poisoning vs. Food infection

• Food poisoning = toxins cause illness; does not require infection by viable cell

• Food infection = illness caused by viable cells

T/F: Food infection occurs when it’s the microbial toxin that cause the illness itself and not viable cells

FALSE

Food poisoning occurs when it’s the microbial toxin that cause the illness itself and not viable cells

Toxins cause food poisoning and can be produced by which groups of organism?

paf

• Protists

• Algae

• Fungi

Enumerate & explain 4 types of seafood and shellfish poisoning (due to toxins); primary causes

*primarily caused by algae, protists

dpan

• Diarrheic shellfish poisoning

  • Mussels, oysters, scallops, clams mosc

  • e.g., Dinophysis fortii (okadaic acid) protist

• Paralytic

  • Mussels, oysters, clams, fish mocf

  • e.g., Alexandrium catenella (saxitoxin) protist

• Amnesic

  • Mussels

  • e.g., Pseudonitzschia pungens (domoic acid) algae

• Neurotoxic

  • Mussels, oysters, scallops, clams

  • e.g., Cymnodinium breve (brevetoxin) protist

Type of seafood & shellfish poisoning you can get from consuming:

• Mussels

• Amnesic

• diarrheic (mosc), paralytic (mocf), neurotoxic (mosc)

Type of seafood & shellfish poisoning you can get from consuming:

• Mussels, oysters, clams, fish

• Paralytic

• diarrheic (mosc), neurotoxic (mosc), amnesic (m)

Type of seafood & shellfish poisoning you can get from consuming:

• Scallops

Diarrheic, neurotoxic

_ are fungal secondary metabolites that can cause fungal diseases called _

• Mycotoxins

• Mycotoxicosis

Enumerate most common mycotoxins

acofz

• Aflatoxin

  • Food: Maize, peanuts, milk

  • Bio effects: Hepatoxins (liver), carcinogens

  • LD50: 0.5 (dog)

• Cyclopiazonic acid

  • Maize, peanuts, cheese

  • Convulsions

  • 9 (rat)

• Ochratoxin

  • Maize, cereals, coffee beans

  • Nephrotoxins (kidney)

  • 20-30 (rat)

• Fumonisin

  • Maize

  • Equine encephalomalacia, pulmonary edema in pigs

  • Unknown

• Zearalenone

  • Maize, barley, wheat

  • Oestrogenic

  • Not acutely toxic

_ are small proteinaceous infectious agents with no nucleic acids but is a modified form of normal cellular protein (misfolded protein); can come from cattle meat and milk

Prions

T/F: Prions are subviral agents with proteins and nucleic acid

FALSE

Prions are subviral agents with proteins and NO nucleic acid

Prions are proteins normally expressed in the _; however, infectious, misfolded ones can cause _

• Brain

• Transmissible spongiform encephalopathy

T/F: Transmissible spongiform encephalopathies (TSEs) are known to affect only humans and animals

TRUE

The native form of prion protein is not only expressed in humans but also in _

mammals, birds, reptiles mbr

Enumerate & explain 4 major characteristics of prion diseases

lldp

• Long incubation period (years)

• Loss of muscle coordination (cerebellum)

• Dementia (loss of memory, intellect, poor judgment)

• Progressive insomnia (marked loss of slow-way-eye-movement phases)

_ is the gene coding for prion protein cellular (PrP^C)

Prnp (prion protein gene)

Prnp is the gene coding for _

Prion protein cellular (PrP^C)

T/F: Mammals, birds, and reptiles have Prnp gene and thus express PrP^C

TRUE

Enumerate 7 symptoms/manifestations of Creutzfeldt-Jakob Disease (CJD)

mbv pp cd

• Memory problems

• Behavioral changes

• Vision problems

• Poor muscle coordination

• Progress quickly to dementia

• Coma

• Death

_ is the normal cellular prion, while _ is its pathogenic form

• PrP^C (prion protein cellular)

• PrP^Sc (prion protein scrapie)

_ is the name of the disease caused by prion in sheeps

Scrapie

T/F: It is hypothesized that normal cellular prions (PrP^C) only have to be exposed to misfolded prions (PrP^Sc) to become infected

TRUE

Enumerate & explain 3 common characteristics of misfolded prions

pia

• Protease-resistant (doesn’t undergo degradation)

• Insoluble

• Form amyloids → insoluble crystalline fibers; prion aggregates; sponge-like structure

Transmissible spongiform encephalopathies, include _

• Creutzfeldt-Jakob disease (humans)

  • Familial insomnia

• Scrapie (sheeps)

• BSE (cattles)

• Kuru “laughing disease” = get when u eat brains (result of cannibalism)

What are the limitations to studying prions?

LS

• Require a long incubation period

• Subject of study is hard to obtain, e.g., humans and mammals

• Not culturable = a living organism is needed