Micro exam 2 :)))))

Define intrinsic factors, name one

Factors in the food like pH

Define extrinsic factors, name one

Factors in the external environment, like temperature

Define implicit factors, name one

Factors implied about the bacteria, like growth rate

Other than intrinsic, extrinsic, and implicit factors what is the fourth factor affecting microbial develpoment

processing factors

Name one food processing factor

pasteurization

The lower the water activity the (LOWER OR HIGHER) the freezing point

lower

In a hypotonic environment how does the cell balance itself

taking in water

When a cell is in a hypotonic environment, this creates

positive turgor pressure

Slow freezing causes what which is dangerous for food

a supercooled (liquid) environment where bacteria can stay alive

Fast freezing is better than slow freezing because

it causes physical damage to membranes and enzymes

Freezing and thawing can have what two main effects on food

nutrient release, breakdown of biological structures

Cooking is defined as a heat process (at what temp)

<=100 C

Blanching is defined as a heat process (at what temp/time)

<100 (for a short time)

Drying is defined as a heat process (at what temp)

<100 C

Pasteurization is defined as a heat process (at what temp)

60-80 C

Apperitisation is defined as a heat process (at what temp)

>100 C

Pasteurization also applies to (other than milk)

wine

Pasteurization for milk was originally designed for killing (2 pathogens)

Mycobacterium tuberculosis, Coxiella burnetti

Low temperature, long time (LTLT) temp and time requirements

63 °C, 30 min

LTLT pasteurization is also known as

vat pasteruization

High temp short time (HTST) temp and time requirements

72 C, 15 sec

UHT temp and time requirements

140-150 C, 1-2 sec

Aseptic packaging is often at what temp

>130 C

Aseptic packaging has 2 benefits

less energy, no cold chain

Common microbial issues in milk are (3 microbes)

LAB, Bacillus, Clostridium tyrobutyricium

Bacillus in milk causes 2 issues

sweet curdling, bitty cream

What bacteria causes late blowing

clostridium tyrobutyricum

Apperitisation is (in normal people terms)

canning

For low acid foods what D value are we looking for (canned)

12D

Name 2 non thermal food processing methods

UV, ionizing radiation

Most food in the us (95%) are processed via

thermal processing

Name 1 physical methods of processing food

HPP (high pressure processing)

HPP is common in what markets

juice, guac

Name 2 advantages of HPP

fresher flavor, works well with compressible foods

Name 2 disadvantages of HPP

damages cell tissue, doesn’t inactivate spores well

What processing method can cause spores to germinate

low pressure HPP

Why does UV light work on bacteria

by forming thymine dimers (mutating DNA)

What can impact UV effectiveness (name 2)

turbidity, UV absorbing molecules

What is the main cause of indirect DNA damage during water radiolysis?

The hydroxyl radical (⋅OH) attacks and breaks the bacterial DNA backbone, leading to cell death.

Order most to least sensitive for irradiation

G-/molds, G+, yeasts, spore formers, viruses

2 advantages of radurization

more even, and less costly than heating

2 disadvantages of radurization

low doses aren’t effective, consumer acceptance

GRAS stands for

generally recognized as safe

These are examples of

Organic acids

• Alcohols (ethanol)

• Allicin, isothiocyanates

• Essential oils

• Nisin, Microguard (pediocin)

• Avidin, ovotransferrin

antimicrobials

Main components of curing

salt, smoke, vinegar, honey

These are examples of

2SO3, Na2SO3, K2S2O5, NaHSO3

sulfites

Lower levels of sulfites (0.1-20 ppm ) control

fungi

Higher levels of sulfites (50-70 ppm ) control

Acetobacter

How do sulfites control bacteria

targets cytoplasmic membrane, DNA/protein synthesis

What controls browning in fruits

sulfites

Potassium bisulfites may NOT be used in foods

meant to be served raw, B1 vitamins sources, or meats

What are nitrates primary target

C. botulinum

Nitrates are mainly found in

cured meats

Source of Benzoic acid (3 sources and pka)

berries/plums/cinnamon, 4.19

Benzoic acid is mainly used to limit

yeasts and molds

Source of Propionic acid (source and pka)

propionibacterium, 4.87

Propionic acid is mainly used in what, and is effective againts

Baked goods, mold mostly but also yeasts and bacteria

Source of sorbic acid (source and pka)

berries of mountain ash tree, 4.75

Sorbic acid is used in what products (3)

cheese, dried fruits, beverages

What is scorbic acid used to inhibit

yeasts and molds

How does natamyacin work

binds ergosterol

Lysozymes are an antimicrobial found in

Egg whites

Are lysozymes effective against yeast and molds

No

Lysozymes are more effective against BLANK bacteria than BLANK

gram positive bacteria than gram negative

Lactoferrin is the primary

iron binding protein in milk

Lauric arginate is good because it works from pH

3-7

A bacteriophage is also known as a:

bacteria virus

What is a common practice to prevent infestation of bacteriophage in an industrial setting?

clean and sanitize the affected area

What is a problem with using bacteriophage?

Bacteria quickly become resistant

Which is a positive aspect of using bacteriophage?

they are harmless to humans

When bacteriophage ruin a fermentation process, it can be called

dead vat

Sulfites work as preservatives through targeting:

 

polyphenol oxidase

 

Cytoplasmic membranes

 

DNA and protein synthesis

 

All of the above

All of the above

What is the driver of developing new antimicrobials to use in foods?

few antimicrobials function in low acid foods

Preservatives we discussed to date originate from:

 

chemical synthesis

 

All of the above

 

eggs

 

bacteria

All of the above

Which preservative is most effective against gram positive bacteria?

lysozyme

Which ingredient is not a naturally occurring source of nitrates?

 

sea salt

 

liquid smoke

 

nutmeg

 

celery salt

liquid smoke

What preservative was removed from bread in the Bacillus outbreak in the Isle of Mann?

 

lactic acid

 

sorbic acid

 

propionic acid

 

acetic acid

propionic acid

Indicator organisms are good because they are

easy and rapidly detectable

What is an indicator organism?

An organisms whos presence indicates poor hygine/sanitation

Coliforms are capable of fermenting blank at what temp

Lactose at 37 C

presence of coliforms indicates possible BLANK contamination, and therefore potential for pathogens transmitted through BLANK contamination

fecal, fecal

Coliforms are part of what family

enterobacteriacea

What is a shortcoming of coliform test

organisms not of fecal origin can grow

Negatives of fecal coliform test

not all E.coli grow well at 44 C

Name the 4 detection styles of bacteria

agar based, ATP, immunological, DNA

ELISA and lateral flow are examples of

Imminological methods

How does a lateral flow assay (LFA) work to detect a target molecule?

The sample binds to colored antibody-linked nanoparticles, flows across a capture line with fixed antibodies to trap the target, and forms a visible colored band if the target is present

Name 2 advantages of a LFA (lateral flow assay)

antibodies are highly specific, simple

Name 2 disadvantages of a LFA (lateral flow assay)

works best with large molecules, inhibitors can be present in foods

Ingredients for PCR (5)

template, 2 primers, Deoxynucleotide triphosphates, TAq

PCR has 3 steps, what are they

denaturation, annealing, extenrsion

2 advantages of PCR

sensitive, easy to develop in-house

2 disadvantages of PCR

dead organisms get picked up, susceptible to cross contamination

3 steps of E.coli testing

potential positive, presumptive, confirmed

The "Dirty 22" is

22 common pest species recognized by the US-FDA as vehicles for spreading foodborne diseases

The specific target gene used for the molecular identification step (DNA barcoding) for the dirty 22 is…

mitochondrial cytochrome oxidase I

use of immunologic and/or PCR assays, with no attempt to grow culture on a plate is known as…

culture independent diagnostic tests

Why are yersinia infections increasing

we are better at detecting it