ANSC 326 Exam 3

what are the 3 preservatives as described by the FDA

chemical preservative

food additive

antimicrobial

chemical preservative

any chemical that when added to food, tends to prevent or retard detroriation

does not inlclude salts, vinegars, and oil extracts

food additive

all substances.. the intended use of which results or may reasonably be expected to result, directly or indirectly, either in their becoming a component of food or otherwise affecting the characteristics of the food

antimicrobial agents

substances used to preserve food by preventing growth of microorganisms and subsequent spoilage, including fungistats, mold, and rope inhibitors

- static

inhibit growth

ex: fungistatic and bacteriostatic

keeps microbial population from increasing but may not show multi log 10 cycle decline

best at preserving lag phase of microbe population

-cidal

kills microbex

fungicide, insecticide, virucide, sporicide

traditional chemical antimicrobials

-Include the synthetic antimicrobial compounds

-Many in use for many years, decades

-Bear regulatory approvals for specific applications in various countries

-Often can be perceived as "bad," despite having natural sources

natural antimicrobials

-All naturally occurring sources

-May be subject to less rigorous approval processes

-Perceived as being "better" because of being natural (green, clean label)

intrinsic factors

food product physico-chemistry and interactions with food product ingredients

extrinsic/ processing factors

how will food be handled post-antimicrobial input

microbial factors (new)

what organisms are being targeted for inhibition

numbers and phase of population growth

potential for adaptation or injury exposure

impact on other microorganisms

microbes physiological status

what are the factors that affect antimicrobial selection

intrinsic

microbial

extrinsic/ processing

method of delivery of antimicrobial

regulatory

direct addition of antimicrobial

quantity used does not exceed that. required for intended technical effect

be of food grade and be handleed as ingredient (labeling)

existence of safe use conditions does not negate a prcoessore req to adhere to other components of the FFDCA (federal, food, drug, and cosmetic act)

indirect addition

-fermentates produced during fermentation

-sanitizers

-packaging components or other compounds reasonably likely to contact food

organic acid reminders

pH based efficacy and most function below pka

may have more tthan 1 donatable protons

can be natural or not

many bear GRAS approval when used in CGMPs= current good manufacturing practice

weak acids

an acid that is only slightly ionized in aqueous solution

and will not fully dissocisate

pka aka dissociation constant

shows how strong an acid is

low pka= strong acid, the proton is NOT held tightly

high pka= weak acid

benzoate/benzoic acid

**1st federally approved organic acid/ antimicrobial

fungistatic: mold inhibitor

sources: berries, cinnamon, cloves, plums

used: bread doughs, salad dressings, and preserves

approved: 0.1%. in meat and poultry

prior sanctioned ingredients or as GRAS

what was the 1st approved antimicrobial

the organic acid benzoic

parabens

Esters of p-hydroxybenzoic acid

--derivative of benzoic acid

acts more like a surfactants

3 approved uses:

*fermented malted beverages (beers)

*non carbonated beverages, fruit breverages

*anti fungal angentt in various applications

*heptyl-paraben

* metthyl- propyl-paraben

ph insensitive 3-8

water soluabilty decreases as antimcrobial activity increases

(chain lenttgh of alkyl chain is esterfied to beenzoatee

less usage bc of push to be more clean and green

surfactant

reduces surface tension of a liquid in which it is dissolved

acetic acid, actetates

CH3COOH, CH3COO- + Na+

more broad spectrum than parabens bc no only antifungal but also antibacterial properties

usage in

0.25% baked goods

0.8% cheese

3% gravies

4% in processed meats

found in natural sources and fermented through acetic acif bacteria (acetobacter)

diacetic acid: appeoved by USDA for carcass decontamination up to 0,25%

lactic acid, lactates

CH3CHOHCOO- + H+/Na+/K+

has D and coformers

broad spectrum like acetic acid with fungal and antibacterial properties

functions: acidification of cytoplasm, may permeabilize GRAM NEGATIVE outter membrane

fermantative outcome from CHO breakdown

GRAS in many food and no limits other than in accordance with CGMPs

meath and poultry carcasses 2-5%

growth inhibition

sanitizer in produce

propianic acid, propionates

• CH3CH2COOH; pKa 4.87; volatile fatty acid

GRAS, no limites other than CGMPs

--some do have limits on antimicrobial applications

antimicrobial and flavoring agent

antifungal applications: breads, sauces, gravies, cheeses, dairy products, soups, processed meats. some alcoholic wines

antibacteerial: rope forming bacilllus spp, some gram negatives included

which preservatives have antifungal properties

benzoic acid

parabens

propionic

sorbic acid

sulfites

sorbic acid, sorbates

GRAS as long as following CGMPs

CH3CH=CHCH=CHCOOH

antifungal

limits C. bot spore germination

nutrient blocking

--inhibits amino acid uptake

acidification

FSIS approved for addition in beef as a mold inhibitor

reduces nitrates and nitrites

citric acid, citrates

CH2COOH-C(OH)COOH-CH2COOH

tri-protic acid

GRAs folowing CGMPs

approved for meat and poultry

not really a surface sanitizer

applied alone or in combinattion with other organic, inorganic acids

incorporated into mulitiple food and meat/ poltry acidulants or as curing accelerantt

nitrates and nitrites

used in cured meats and poultry foods (components of curing salt)

functions to modulate EH( erythorbate, ascorbate)

used in bacon and smoked fish

plants and vegetables are natural sources used in meat and poultry

prevents c. bot spored from germinating by disrupting thee outgrowth phase prior to tthe cell returning to vegetiative state

when broken down during cook, the c. bot cant germinate

Phosphates, Polyphosphates

chelator-- binds cations (fe2+ and calcium) that are used to stabilize the outer cell wall membrane

not widely used as other antimicrobial

BEST AGAISNTT GRAM POSITIVE BACTERIA

chelator

binds cations and prevents the microbe from being able to replicate and thrive

sulfites

usually used as a food surface sanitizer

usda doesnt alllow in food and poultry

if used in fuits and vegetables, it cant be marked as fresh

enzyme denaturation activity--reduction of disulfide bonds

week acid mechanisms and most functiona at pHs lower than 4

added to wines for spoilage prevention by yeasts and bacterias

used in processes, dried produce items to help prevent microbial, enzymatic spoilage and discoloration

lysozyme

enzyme naturally in egg albumen, tears

GRAS 1998: prevent cheese spoilage

USDA approved in salads sauces with meat or poultry

removed from USDA list of approved compounds for manufacture of organic foods in 2016

most effective against gram positive bacteria butt can show activity against gram negatives when combined with membrame- chelator

--bacteriostatic

--eats through cell wall by breaking the bond between NAG AND NAM

Lactoferin and Chelating enzymes

lactoferin is secreted in cows, and other livestock milk

--chelates 2 atoms of Fe 3+ with coenzyme bicarbonate (2 molecules HCO3-)

--restricts microbial access to critical nutrient, iron(LPS complexing, iron sulfur enzymes)

ovotransferrin: similar iron binding protein found in egg white

--requires bicarbonate to co-enzyme

both are bacterio and fungistatic!!!!

req alkaline condition to facilitate activity

recall that it is iron prefrentially but can bind other cations

avidin

A protein in raw egg whites that binds b-vitamin biotin (4 biotins/ advin) and is useful as a nutrient sequestrant

ovomucoid

inhibits trypsin

in egg white

prevents protease attack on egg protein compoun

protects rheological properties to restrict microbial motility

lactoperoxidase

2-component antimicrobial system in mammal milk

produces ROS and HSCN from naturally occurring respiration intermediates in milk --req microbial activity to inhibit gram positive aerobes and anaerobes

not in foods in US, but in mouthwash

suggested in worldwide use where pasteurization isnt available

antimicrobials as food surface sanitizers

-chlorines and hypochlorite

-quaternary ammonium compounds (QACs)

-Peracids/Peroxyacids

-applied under strict limits on use to food surfaces (produce, meat, poultry)

-not labeled on foods, applied as processing aids

-may require rinse off prior to further processing

-some concerns over toxicity at higher levels

Chlorous Compounds

-Oxidizer-type antimicrobial mechanisms

--oxidzier attacks dna, protein and organic material to where the microbe cant replicate

-Approved for multiple food types as surface disinfectant

not really on meat because it effects the color

must wash off if past alloted amount

• NaOCl/HOCl is most commonly applied compound

• ClO2: Colorless, odorless gas that can be applied aqueously

--gas is bubbled in water and used to wash vegetables

QACs: Cetylpyridinium Chloride

nitrogen bonded to 4 quaternizing substituted groups (alkyl chains or other organic molecules)

cationic surfactant mechanism: gram + most suscptible but are active against other bacteria and viruses

only cpc allowed to actually touch food surface

most expensive, and is why PAA is used the most often

used on fresh poultry

released of membrame bound proteins

inhibition of glycolysis

membrane destabilization

physical processing

dehydration

low temp

holding

heating and cookig

what is processing of foods

minor or major stress to microbes: inhibition of growth, inactivation/ death

processing helps protect microbiological safety, quality, shelf like

physical one

peroxy- acids

bend of hydrogen peroxide and organic acid like acetic

used in poltry. chiler waters, and meat cooler waters

oxidizer/ acidulant activity

useful for produce wash waters sanitization in addition to meat and poultry

NOT A FOOD ADDITIVE, ONLY A SANITIZER

synthetic

Spice/Plant-Derived Antimicrobial (PDA) Extracts

GRAS as flavor-ants and aromatic compound

cant have toxic organic solvents or be steam distillation captured

some have EOC data

--cinnamon, clove, thymer, sage, ginger, garlic

antibacterial and antifungal

--better on gram positive than gram negative

--attack enzymes

--negative outer membrae can screen membrane active EOCS

problem: non water soluable when most foods are, rsearch on encapulsattion delivery

Oils comprised of multiple types of compounds: phenolics, terpenoids, isoprenes, aldehydes, et al.

eoc activity

essential oil componentts

allicin

spice derivitive

organo-sulfers from members of plant genus allium (alters protein folding)

garlic, onions, shallots, leeks, and others

pungent, release from plant cells by disruption of cellular membranes

activated by allinase on substrate allin

--reaction is why you cry with an onoion

causes cell death in positive, negative, bacteria, and fungi

oxidize sulfhydryls to disulfides ; respirattion inhibirion/ uncoupling from reproduction

--enzyme catalysis loss

IsothiocyanateProducing Plants

R-N=C=S

producded by members of plant family Brassicaceae (cruciferae)

mustard and wasabi

--cruicerfous veggies

released during processig following myrosinase acting upon glucosinolates

gram negatives are more susceptible , mechanisms are like sulfurous and allicin

useful in low concentration either in vapor phase or in higher content medium

Mono-Phenolics (Phenolics)

- probably the best studied and some of the most diverse class of compounds

- some have proven antimicrobial activity

- membrane destabilizing, but can also

disrupt PMF and energetic processes

- gram positive and negative bacteria are sensitive

-hydrophobic

--effects mircobe energy production and use

what is biopreservation

The extension of shelf life and enhanced safety of foods by use of natural or controlled microbiota and/or antimicrobial compounds

what are the 3 applications of biopreservatives

fermentative non pathogenic microbes, principally the lactic acid bacteria (LAB)

fermentates from non pathogenic fermentative microbes, purifies and added to other foods (acids and bacteriocins)

bacteriophages: bacteria eating viruses

fermentative microbes

lactic acid bacteria (LAB)

--useful for acid production in food stuff (procided sufficientt sugar and utility)

organic acids, fatty acids and acid esters

colonization of food niches or competition with pathogens for available nutrients

secondary metabolite

not trying to ferment the food

its the chem compounds when fermenting sugars that is killing the microbe

application of biopreservative cultures for food protection

focused on meat, poultry and seafood ....some on produce

utility influenced by --food chemistry (nutrient profile, avialability)

--food handling and holding and the growth capacitiy under such conditions

--number of pathogens expected versus biopreservative inoculum

--foods buffering capacity against acid production

antimicrobial metabolite products

- produced via industrial fermentation, purified/semi-purified, stabilized and packaged

- approved for application across various food product types

- produced by known non-pathogenic microbes

- comprised by some combination of: acids, antimicrobial peptides, peroxides, misc. antimicrobials

bacteriocins

toxic proteins(from polypeptides yo enzymes) that kill other bacteria

genetically encoded, produced in ribosome and then enzymatically activated post translation

produced by gram positive against other gram positive lol

bacteriocin immunity

Bacteriocin-producing organisms must maintain immunity to their own antimicrobial

-Genetically-encoded immunity systems

-Membrane non-susceptible

-Exporting of bacteriocin

-Disruption of immunity-related genes provides sensitivity to bacteriocin of producing strain

E-Poly-L-Lysine (EPL)

GRAS

fermentative from streptomyces albulus

gram positive, negatieve and fungi

poly cationic-disruption of cell membrane components, surface charge maintenance

Colicins and Microcins

gram negative produced microbes

aka what bacteriocins are for positive bacteria

bacteriophages

viruses that infect bacteria

high host specificicity

ongoing co evolution of host and parasite agaisnt one another

FIRST GRAS APPROVED AGAINST L. MONOCYTIGENES IN RTE FOOD

approved in food animal and food for reducing pathogens

limitation: may be to host specific fx

pathogen of consern

most process tolerant microbe of public health conccern for which processing is required to establish product safety

what does high protein, fat, and polysaccardide content do for microorganisms

provides insulation to processing (heating cooling, water degydration, etc

what effects rate of drying

food composition and fraction of loosely bound/ available water versus non available bound water

drying medium (humidity in heated air)

rate of air movementt over food (covective)

mircobes anticipated in food pre drying and post handling

lethalithy: lows, but occurs due to high heat, low moisture and development= irrecoverable injury

Freeze-drying (lyophilization)

more gentle dehydration process than forced air

ice forms in thee food

--under controlled temp/ pressure conditions, then sublimates to vapor

easier rehydration and less degradative to food micro structure

growth inhibited

non continuous systeem and high energy input, but higher quality is retaineed

TCS

Time and Temperature Control for Safety

foods that req time/ temp control to limit pathogen growth or toxin production

FDA Food Code temperatures refrigerated

41 F or 5c

exception is eggs (45F and 7.2C)

USDA- FSIS meat cooling req

cooked meats must be chilled to less than 40F post lethality

raw meat and poultry must be stored cold

• Rate of cooling and achieving desired cold storage temperature a function of:

*

food chemistry and mass •

Impacts of packaging (if packaged) on heat loss •

Cooling technology and efficiency at heat stripping • Still versus blast air cooling, IQF • Cooler temperature and heat gradient between food, cold air

how does cold temps slow down microbe

slows, halts enzymatic, chemical reactions

limitations on reaction kinetics

psycotrophic still have slow growth and replication

homeoviscous adaptation

microbe willexchange, modify long saturated fatty acids (SFA) for shorter SFAs or unsaturated fatty acids to maintain membrane fluidiity

colder temp leads to phase change (liquid to solid or gas to liquid)

in microbes, water turns to ice or fats crystalize/ gel

lipids mist remain fluid for proper executtion of essential biological processes

eutectic T

point where food components reach solubility limit and all water freezes

food freezing

foods frozen to less than -18C and regulated to stay frozen until preparation for consymption

freezing of water happens over broad temp range

inactivation of helminths and some bacterial reduction

food chemistry can retard freezing rate and allow for longer microbial survival

how does freezing effect microbes

concentrates solutes and prevents microbial access (nutrient sequestration localized aw depression)

osmotic shock!!!!

--pH, aw impacts solutes concentration

--localized dehydration as liquid water migrated to maintain water =librium

mechanical injury from ice, nucleate

for food safety, freeze slow

for food quality, freeze fast

compatible solutes

compounds used by cell to counteract low water activity in surrounding environment

not metabolized by the cell

what does thawing do to microbe

oxidative, thermal shock!!

repeated cycling of freezing and thawing shows enhancded microbial impacts but sttromger food quality damage

fda recommends

--slow that at less than 5C

--microwave if being immediettly cooked

--under running water 21C for not more than when food rises to above 5C or raw deribed animal for 4 hrs

Thermal Processing of Food: Defining

pasteurizatiom

commericial steriility

blanching

hot fill:

pasteurization

Process designed to eliminate/reduce most process-resistant non-sporulating pathogen of concern to non-threatening numbers during post process handling, as well as significantly reduce non-pathogenic spoilage

Commercial Sterility:

Absence of pathogens and other microbes capable of replication under shelf storage conditions post-processing

--low acid canned foods pH greater than 4.6 and aw greater than 0.85

--aicd, acididifed canned foods pH less than 4.6 and water activity greater than 0.85

blanching

application of moderate heating to foods to innactivate enzymes carrying enzymatic spoiage (most fruqent in plants and produce)

hot fill

Non-sterilized container is filled with sufficiently hot food to render final product commercially sterile

who created the first canning and who enhanceed it

appert created, durand improved

why cook in package and why not

functional for preserving food and preventing post process contamination

--canning

--sous vide aka under vacuum

food cooked seperately from packgape and aseptically filled post process

aspectic processing and packaging

cook indep of package

food is fully cooked and packing material is sanitized with peroxide

useful for liquid foods (no particulates), foods suffering quality loss it extensively thermally tested

impact of heat on microbes

denaturez enzymes and casses loss of structure, catalysis and folding

permeabilizes membrane and releases membrane bound proteins

--allows leakage of cytoplasmic contents

dna unfolding and attack

enhances antimicrobial activity of chemical antimicrobials (acids and bacteriocins) or physical processing with high pressure

can produce sub lethal injury if not sustained sufficiently to inactivate contaminating microbes

sub lethal heating

can lead to increased tolerance to subsequent heat exposure

result of heat shock proteins and dna chaperone proteins

protects against more substantial microbial damage

cross protection against other stressors

thermobacteriology

traditiona

1st order kinetics via application of moist heat

at 5 mins 90% are killed and at 10 mins 99% are

at constant temp, the microbial death rate becomes constant

D value (decimal reduction time)

time in min at a constant temp achieving a 1.0 log 10 cycle reduction (90% reduction) in population of microbe

D=2.3/kt

D=(t2-t1)(logN1-logN2)

t being time

log

the power to which a number must be raised in order to get another number

thermal resistance constant- z value

impact of changing process temperature on resulting lethality to microbes

defined: temp change producing a 10 fold change in value of

z= (T2-T2)/(log DT1-logDT2)

t being temp

what does higher z values mean

higher tolerance to change in processing temp

thermal death time (f value)

Time required at constant temperature with known z-value to destroy a desired/required number of microbial cells

f naught

universal refrence thermal process, set at 250F or 121.1 C with z=18F or 10 C

used to compare lethalities achieved at other temperatures

F sub set T

FT= DT(logN1-logN2)

f value is specific to a microbe at specific d value

log N is log 10 of count for initial plate count (N1) or final plate count (N2)

F-value Application in Industry Processing

Botulinum Cook (12D process, LACF) • Cooked meats, poultry: 6.5, 7.0 log10 Salmonella Lethality requirement • Milk: 6D cook of C. burnetii • Pressed, bottled juices: 5D (FDA mandate) for pathogen of concern

Non-Linear Death Kinetics

Much data shows microbials don't die linearly!

• Opportunities for slow, rapid, no apparent inactivation by heating, even at lethal temperatures!

• Determination of most conservative death rate, overall death rate?

• Complicates lethality assessment

• Shoulders, tails • Persistence

what are the steps for acceptance of novel processig tech

1. relevant reguatory agency approves tech

2. industry member complete scientific validation

3. consumers give acceptance by purchasing food made with tech

• Setting thermal and non-thermal processes as equivalent relies on benchmarking processing against desirable levels of safety

Set up process-specific pathogen lethality targets

• Process-specific FSOs, Performance objectives

High Pressure Processing (HPP)

application of very high pressure (100-500Mpa) for some time period to packaged foods

dependent on food geo, volume and mass

near instantaneous =libration of pressure through chamber (pascals principal)

pressure transmitting fluid required (water, glycerin in water)

can produce macromolecular changes

run as single process or clinical pressurization + decompression

batch pr semi- continous processing.

Pressure-Assisted Thermal Sterilization/Processing (PAT)

• Temperature necessarily rises in HHP (falls during decompression)

• Accelerated process available by controlled pressurization/heating

• May maintain near adiabatic process (no exchange of heat or mass)

pressure mechanism of microbial inactivation

Enzyme/protein denaturation

• Ribosome destruction (replication inhibited)

• Membrane permeabilization and release of LPS from membrane(like heat)

• Irreversible compression

• Inactivation can be enhanced by:

• Use of heat (PATS) • Antimicrobials in food (acidulants, other antimicrobials)

Microbial Baro-Tolerance and Lethality Determination

• Microbial inactivation follows first order kinetic (similar to thermal)

DMPa: Time (min) at constant pressure producing a 1.0 log10-cycle reduction in microorganism

Lengthening the processing time may not increase lethality significantly

Ultraviolet (UV) Light*

• Type C light (254 nm) is germicidal

• Can be applied to liquid and solids à best with clear liquids (water, clear juices)

Induces non-ionizing effects in microbial DNA, RNA to kill microbial cells

Pulsed Electric Field

Food passed through electrical field, producing potential across microbial membrane

Membrane breakdown and cellular content leakage (electropermeabilization), cell explosion

• 10-100 kV/cm field development

Used mainly for liquid foods, but can be used in some solid food applications (breads, crackers)