FMLec | M5: Food Preservation, Food Safety, & Food Plant Sanitation

Give 6 aspects of food preservation, food safety, & food plant sanitation

• Traditional food preservation (methods)

• Novel techniques in food preservation

• GMP (Good Manufacturing Practices)

• HACCP (Hazard Analysis Critical Control Point)

• Food defense

• Risk assessment

Enumerate 6 traditional food preservation methods

chembio moralodry

• Chemicals

  • Chemical preservatives

• Biocontrol

  • LAB

  • Bacteriocins

  • Phages

• Modified atmosphere

  • Hypobaric storage

  • Vacuum packaging

• Radiation

  • EMR

    • UV rad

    • Ionizing rad

  • Radiation treatments

    • Raddapertization

    • Radicidization

    • Radurization

• Low & high-temperature

• Drying

_ is a traditional food preservation method that involves the use of compounds that can prevent or delay food spoilage, e.g., generally recognized as safe (GRAS) food additives

Chemical preservatives

Enumerate 9 common chemical preservatives / GRAS (as traditional food preservation method)

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• Propionic acid (propionates)

• Sorbic acid (sorbates)

• Benzoic acid (benzoates)

• Parabens

• Sulfur dioxide

• Nitrates & nitrites

• NaCl

• Sugar

• Indirect antimicrobials

• _ is a chemical preservative highly specific against molds (fungistatic)

• Contains acids or calcium & sodium (Ca, Na) salts (0.32% max)

• e.g., bread (“rope inhibitor”), cakes, cheese (Swiss), low-acid food

• Results in weakened transmembrane gradient due to lower intracellular pH from proton leakage, consequently inhibiting AA transport

Propionic acid (propionates)

Explain preservation mechanism of propionic acid / propionates

Results in weakened transmembrane gradient due to lower intracellular pH from proton leakage, inhibiting AA transport

Propionates usually contain acids or calcium & sodium (Ca, Na) salts at _% max concentration

0.32%

• _ is a chemical preservative considered to be primary fungal inhibitors and inhibitors of bacteria, including S. aureus, Salmonella, coliforms

• Contain 0.2% max conc of calcium, sodium, potassium (CaNaK) salts

• Preserves hard cheese, syrups, salad dressings, jellies, cakes hssjc

• More effective in acidic foods > neutral foods

• Weakened transmembrane gradient due to lower intracellular pH from proton leakage, inhibiting AA transport

Sorbic acid (sorbate)

_ is a chemical preservative known to be primary fungal inhibitors and inhibits bacteria, including _

• Sorbic acid (sorbate)

• S. aureus, Salmonella, coliforms

Chemical preservative that preserves ff. food

• Bread (“rope inhibitor")

• Cake

• Cheese (Swiss)

• Low-acid food

Propionic acid (propionate)

Sorbic acid (sorbates) contain _ salts

0.2 % max concentration of Ca, Na, K salts

_ is a chemical preservative highly specific against molds (fungistatic) and contains acids or calcium & sodium salts (0.32% max)

Propionic acid (propionates)

Chemical preservative that preserves ff. food

• Hard cheese

• Syrups

• Salad dressings

• Jellies

• Cakes

Sorbic acid (sorbates)

T/F: Sorbates has the same preservation mechanisms as propionates and benzoates

TRUE

Weakened transmembrane gradient from lower intracellular pH due to proton leakage, inhibiting AA transport

T/F: Sorbates are more effective in preserving neutral foods than acidic foods

FALSE

Sorbates are more effective in preserving acidic foods > neutral foods

T/F: Benzoates inhibit both bacteria and fungi at 30 ppm

FALSE

• Fungi = 30 - 500 ppm

• Bacteria = 50 - 500 ppm

• _ is a chemical preservative that acts as fungal inhibitor at 30 ppm but can inhibit bacteria at 50 - 500 ppm

• Most active at lowest pH values of foods (0.1% max)

• Essentially ineffective at neutral values

• e.g., margarine, apple cider, soft drinks, tomato catsup, salad dressings masts

• Weakened transmembrane gradient due to lower intracellular pH from proton leakage, inhibiting AA transport

Benzoic acid (benzoates)

T/F: Benzoates are more effective at preserving foods with neutral pH values than acidic ones

FALSE

Benzoates are most active at lowest pH of foods (0.1% max), while essentially ineffective at neutral values

Chemical preservative that preserves ff. food

• Apple cider

• Soft drinks

• Margarine

• Tomato catsup

• Salad dressings

Benzoic acid (benzoates)

• _ is a chemical preservative that serves as a bacteria & fungal inhibitor at 0.1% max

• Less sensitive to pH than benzoates

• e.g., bakery products, soft drinks, pickles, salad dressings bsps

Parabens

T/F: Benzoates are less sensitive to pH than parabens

FALSE

Parabens are less sensitive to pH than benzoates

Chemical preservative that preserves ff. food

• Bakery products

• Soft drinks

• Pickles

• Salad dressings

Parabens

Bacteriostatic vs. Bactericidal vs. Bacteriolytic

• Bacteriostatic = inhibits but does not kill them

• Bactericidal = kills without lysing them

• Bacteriolytic = kills by lysing them

• _ is a chemical preservative that is bacteriostatic against Acetobacter & LAB at low pH

• Yeasts & molds

• Bactericidal at higher concentrations

• e.g., dried fruits, lemon juice, molasses, wines, fruit juices dlmwf

• MOA

  • Strong reducing power (reducing oxygen tension)

  • Enzyme inhibition

Sulfur dioxide (SO2)

Chemical preservative that preserves ff. food

• Dried fruits

• Lemon juice

• Molasses

• Wines

• Fruit juices

Sulfur dioxide

T/F: Sulfur dioxide is bactericidal against Acetobacter & LAB at high pH

FALSE

Sulfur dioxide is bacteriostatic against Acetobacter & LAB at low pH

T/F: Sulfur dioxide can be bacteriolytic at higher concentrations

FALSE

Sulfur dioxide can be bactericidal at higher concentrations

Sulfur dioxide’s potential mode of action include _

• Strong reducing power (reduction of oxygen tension)

• Enzyme inhibition

• _ is a chemical preservative used in curing meats

• Inhibits some spoilage and food poisoning organisms

• Stabilizes red meat color and contributes to flavor development

• Have anti-botulinal & anti-clostridial effects

Nitrites & nitrates

_ is a chemical preservative with anti-clostridial & anti-botulinal effects; can inhibit some spoilage & food poisoning organisms

Nitrites & nitrates

• _ is a chemical preservative with high salt concentrations and thus causes drying effect in both food & microorganisms

• Preservation of fish & other meat products without refrigeration

• Most nonmarine bacteria are inhibited by 20% or less conc

• Some molds generally tolerate higher levels of this (bc they can tolerate lower A_w)

NaCl

T/F: Some molds generally tolerate higher levels of NaCl

TRUE

Most nonmarine bacteria can be inhibited by _ NaCl

≤ 20%

Chemical preservative that preserves ff. food

• Fish, other meat products without refrigeration

NaCl

Chemical preservative that preserves ff. food

• Cured meats

• Red meats

Nitrites & nitrates

• _ is a chemical preservative with the same MOA as NaCl

• Bacteria is more susceptible to this than fungi

• e.g., fruit preserves, candies, condensed milk fcc

Sugar

T/F: Higher concentrations of sugar is needed to preserve food than salts

TRUE

While sugar has the same MOA as NaCl (i.e., reducing Aw), it is less potent and thus higher concentrations would be needed for it to have the same effect

_ is a chemical preservative used in curing meats; stabilizes red meat color & contributes to flavor development

Nitrites & nitrates

Chemical preservative that preserves ff. food

• Fruit preserves

• Condensed milk

• Candies

Sugar

_ are chemical preservatives considered multifunctional food additives because they have a different primary use but have antimicrobial effects, e.g., vanillin = flavoring, lauric acid = defoaming agent, BHA = antioxidant

Indirect antimicrobials

_ is a traditional food preservation method that refers to the inhibition or control of pathogens using 1 or more living organisms or their products (nonliving), e.g., LAB, bacteriocins, phages

Biocontrol

• _ is a biocontrol agent that can perform _ antagonism & microbial interference (nonspecific inhibition / destruction)

• Inhibits or kills closely related bacteria via phbpn

  • Produce antibiotics

  • H2O2 (ROS)

  • Bacteriocins

  • pH depression (low/acidic)

  • Nutrient depletion

LAB

T/F: While LAB can be used as biocontrol agent producing antibiotics, H2O2, bacteriocins, lower pH, & deplete nutrients, they can still be agents of spoilage

TRUE

LAB can inhibit or kill closely related bacteria via _

phbpn

• Production of antibiotics

• H2O2

• Bacteriocins

• pH depression

• Nutrient depletion

T/F: LAB can perform antagonism and microbial interference (nonspecific inhibition/destruction)

TRUE

_ is a biocontrol agent that refers to ribosomally synthesized antimicrobial peptides rsap from bacteria that can kill or inhibit bacterial strains closely related (narrow-spectrum) or nonrelated (broad-spectrum) to bacterial producer

Bacteriocins

T/F: Narrow-spectrum antibiotics can only inhibit either Gram (+) or (-), while broad-spectrum can inhibit both and thus will have higher chances of inducing AMR

TRUE

BSA are more likely to induce AMR bc more types of bacteria will experience selection pressure and potentially evolve resistance mechanisms against this

T/F: Only Gram (+) bacteria produce bacteriocins

FALSE

Almost 99% of all bacteria can produce bacteriocins, both Gram (+) and (-)

T/F: Bacteriocins are ribosomally synthesized antimicrobial peptides used as biocontrol to kill or inhibit only closely related strains

FALSE

Bacteriocins are ribosomally synthesized antimicrobial peptides used as biocontrol to kill or inhibit both closely related (narrow-spectrum) or nonrelated (broad-spectrum) strains

• _ is a biocontrol agent specific for given bacterial species and strains

• Effective in destroying their host cells, e.g., L. monocytogenes, E. coli 0157:H7, Salmonella les

(Lytic) phages

T/F: Phages are host-specific, meaning these are only effective against their host cells

TRUE

T/F: Plants can also be biocontrol agents

TRUE

Some plants release secondary metabolites, e.g., essential oils, that inhibit bacterial or fungal growth

T/F: Lytic phages are more useful in food preservation

TRUE

Bc the goal is to kill bacteria

T/F: Lysogenic phages can effectively destroy their hosts, including L. monocytogenes, E. coli 0517:H7, Salmonella

FALSE

Lytic phages are specific for given bacterial species & strains and can effectively destroy their host cells, including L. monocytogenes, E. coli 0517:H7, Salmonella

_ is a traditional food preservation method that alters gaseous environment on & around foods for purpose of extending their shelf-life; consists of various ways thru which CO2 is used as food preservative, e.g., hypobaric storage, vacuum packaging

Modified atmosphere

_ is a modified atmosphere tradtl food preservation method utilizing low pressure & temperature but high humidity lpt hh to reduce O2 concentrations (lowering Eh and thus aerobe growth)

Hypobaric storage

_ is a modified atmosphere tradtl fpm where air is evacuated from a gas-impermeable pouch followed by sealing, thus reducing O₂ concentrations

Vacuum packaging

T/F: CO2 can also be used to increase CO2 concentration and reduce O2 concentration in food packaging for food preservation

TRUE

_ is a traditional food preservation method involving electromagnetic radiation (EMR) as the primary interest in food preservation; shorter wavelengths are most damaging to microorganisms

Radiation

T/F: EMR is of primary interest in food preservation, with longer wavelengths most damaging to microorganisms

FALSE

EMR is of primary interest in food preservation, with shorter wavelengths most damaging to microorganisms

The 2 most commonly used EMR for traditional food preservation are _

• Ultraviolet (UV) light = nonionizing bactericidal agent (2600 Å Angstrom)

• Ionizing radiation = cold sterilization; beta rays, gamma rays (cheapest), x-rays, microwaves bgxm

_ is an EMR tradtl fpm that refers to nonionizing bactericidal agent at 2600 A, causes lethal mutations and is mainly for surface applications (e.g., baked fruitcakes)

UV light

T/F: There should be a direct UV light exposure to kill microbes in food

TRUE

Remove cover of petri dish to directly expose E. coli colonies to UV and kill them

_ is an EMR tradtl fpm that contains enough energy to ionize molecules in their path; works via cold sterilization, e.g., beta rays, gamma rays (cheapest), x-rays, microwaves

Ionizing radiation

Ionizing radiation, e.g., beta, gamma, x-ray, microwaves, is used as a traditional food preservation method via _, where food is sterilized (and endospores are eliminated at some point) without using heat

cold sterilization

T/F: Ionizing radiation contains enough energy to ionize molecules in their path and works via hot sterilization, including beta rays, gamma rays (cheapest), x-rays, microwaves

FALSE

Ionizing radiation contains enough energy to ionize molecules in their path and works via cold sterilization, including beta rays, gamma rays (cheapest), x-rays, microwaves

Enumerate & describe 3 radiation treatments of foods

• Radappertization = equivalent to radiation sterilization or “commercial sterility”

• Radicidation = reduction of viable specific non-spore forming vsnp pathogens to an undetectable level

• Radurization = substantial reduction of viable specific spoilagen microbes vssm

T/F: Radicidation entails completely eliminating all viable, specific non-spore forming pathogens in food products

FALSE

Not necessarily. There could still be vsnp but are just kept at undetectable levels

T/F: The main difference between radurization and radicidation is that the former reduces viable specific spoilage microbes, while radicidation reduces viable, specific non-endospore forming pathogens to an undetectable level

TRUE

_ is a radiation treatment equivalent to radiation sterilization or “commercial sterility”

Radappertization

T/F: Radicidation refers to radiation treatment that reduces viable, specific endospore-forming pathogens to undetectable level

FALSE

Radicidation refers to radiation treatment that reduces viable, specific non-endospore-forming pathogens to undetectable level

Enumerate 3 factors affecting success of irradiation

• Type, number, & age of organisms

• Food composition & physical state

• Oxygen

Bacteriocin vs. Antibiotics

• Bacteriocin = primary metabolite; ribosomally synthesized antimicrobial peptide; produced during log phase

• Antibiotic = secondary metabolite produced during stationary phase

T/F: Both microorganisms and food will have implications on use of irradiation as food preservation method

TRUE

Factors affecting success of irradiation: tfo

In terms of types, numbers, & age of organism (as factor affecting irradiation success), which of the ff. would be more resistant to effects of UV? gsm fhl

• Gram (-) or Gram (+)?

• Spore-former non-spore former?

• Molds or yeasts?

• Fungi or bacteria?

• High or low density?

• Lag or log?

• Gram (+) = thicker peptidoglycan layer in cw

• Spore-formers = thick, multilayered coats; DNA-protective proteins; low water content

• Molds = produce spores highly resistant to environment stresses

• Fungi = tougher cell walls made of chitin

• High density = more would survive

• Lag phase = bc it’s not actively dividing as opposed to log phase, where DNA is actively replicated and thus prone to DNA-damaging effects of UV

_ is a radiation treatment that reduces viable specific spoilage microbes

Radurization

T/F: Actively dividing microbial cells are more protected and resistant to UV than those not actively dividing

FALSE

Actively dividing ones will have DNA damaged from dimerization effects of UV light

In terms of food composition & physical state (as factor affecting irradiation success), which of the ff. would be more resistant to effects of UV? pdf

• Protein-containing or non-protein-containing?

• Dried or moist cells?

• Frozen or nonfrozen cells?

• Protein-containing = proteins have protective effects

• Dried = moist cells have water on surface that absorbs UV and is thus more affected; water generates free radicals

• Frozen = crystals have protective effect; enzymes are inactive

In terms of oxygen (as factor affecting irradiation success), which of the ff. would be more resistant to effects of UV? the pdf

• Anaerobic or aerobic?

Anaerobic = their metabolic processes do not rely on O2 and thus less likely to undergo oxidative damage from UV exposure; also have physiological mechanisms to protect themselves from UV light

_ is traditional food preservation method relying on principle that rate of enzyme-catalyzed metabolic rxns are temperature-dependent; at above freezing temperature, microbial activities slow down; at subfreezing temperatures, these stop

Low-temperature fpm

Enumerate & explain temperature ranges of low-temp stored foods

• Chilling temp

  • Between ref temp (5-7C) and ambient temp (10-15C)

  • e.g., Certain fruits & vegetables

• Refrigerator temp

  • 0-7C, but ideally not higher than 4.4C

  • e.g., Milk

• Freezer temp

  • At or below -18 C

  • Free water freezes and forms ice crystal

  • e.g., Meat

_ is a radiation treatment that reduces viable, specific non-endospore forming pathogens to an undetectable level

Radicidation

Enumerate 2 basic ways of freezing (as low-temp tradtl fpm), differentiate

• Quick/fast freezing

  • Reaches -20C within 30 mins

  • Via

    • Direct immersion or indirect contact of foods with refrigerant

    • Using air blasts of frigid air blown across foods being frozen

  • Favors small intracellular crystal formation, allowing the killing of more cells

• Slow freezing

  • e.g., home freezer

  • Reaches desired temp within 3-72h

  • Favors large extracellular crystal formation

_ is a basic method of freezing that leads to formation of small intracellular crystals, killing more cells; reaches -20C within 30 mins; direct immersion or indirect contact; using air blasts of frigid air blow across food

Quick / fast freezing

Enumerate 6 effects of freezing on microorganisms

dvc pdm

• Dehydration

• Increase in viscosity of cellular matter

  • General alteration of colloidal state of cellular protoplasm

  • Concentration of cellular electrolytes

• Loss of cytoplasmic gases (e.g., O2)

• Changes in pH of cellular matter

• Denaturation of cellular proteins

• Metabolic injury to some microbial cells

_ is a freezing method that kills bacteria via cell membrane disruption, dehydration, and oxidative damage cdo, but also affects the texture, flavor, and other nutritional qualities of frozen product

Repeated freeze-thaw cycle

Repeated freeze-thaw cycle kills bacteria through _ but also affects texture, flavor, and other nutritional qualities of frozen product

cdo

• Cell membrane disruption

• Dehydration

• Oxidative damage

Psychrophiles vs. Psychrotrophs

• Psychrophiles

  • Cold-loving, thus have to be in an environment thats constantly cold

  • Can be killed by warming to moderate temp

• Psychrotrophs / psychrotolerants

  • Can grow at 0C but have an optima of 20 - 40C

  • Cause spoilage of meat, vegetables, poultry mvp

T/F: Generally, there are more psychrotrophs than psychrotolerants

FALSE

Psychrotrophs / Psychrotolerants > Psychrophiles

Gram(-) = Pseudomonas, Shewanella, Vibrio
Gram (+) = Brochotrix, Enterococcus

_ is basic method of freezing that forms large extracellular ice crystals; reaches desired temp within 3-72 hrs; e.g., home freezer

Slow freezing