Microbial Growth Control and Food Microbiology

These flashcards cover key concepts and definitions related to the control of microbial growth and food microbiology.

Sterilization is any process that kills or destroys __ forms of life, including bacterial endospores.

all

Disinfection is any process that reduces a microbial population on an __ surface to an acceptable level.

inanimate

Antisepsis is any process that reduced a microbial population on __ tissue to an acceptable level.

living

The suffix ‘-cidal’ is used to identify agents that __ microorganisms.

kill or destroy

The suffix ‘-static’ is used to identify agents that do not kill, but only __ the growth of microorganisms.

inhibit

Dry heat kills organisms by __ proteins and lipids.

oxidizing

Moist heat kills organisms by __ proteins and membrane lipids.

denaturing

Pasteurization is a method of __ that uses gentle heating.

disinfection

Non-ionizing radiation (ultraviolet (UV) light) induces the formation of __ dimers within strands of DNA.

thymidine

Ionizing radiation includes x-, γ-, and __ rays.

cosmic

Filtration uses filters to physically remove microorganisms from a __ solution.

liquid

Many of the chemicals used as disinfectants/antiseptics vary in effectiveness depending on concentration and __ of exposure.

time

Halogens are __ agents that oxidize macromolecules.

-cidal

Alcohols are __ agents that solubilize membrane lipids.

-cidal

Phenols are __ agents that denature protein and disrupt membranes.

-cidal

Detergents are __ agents that solubilize membrane lipids.

-cidal

Heavy metals are __ agents that precipitate protein and poison enzymes.

-cidal

A chemotherapeutic agent is a chemical that interferes directly with the proliferation of microorganisms at __ tolerated by the host.

concentrations

An antibiotic may be naturally occurring or __ synthesized.

chemically

Antimycotics are agents that kill or __ the growth of fungi.

inhibit

The Kirby-Bauer Method is a disc diffusion assay used to determine antimicrobial __.

effectiveness

To create a lawn of bacteria for the Kirby-Bauer Method, a __ standard is used.

0.5 McFarland

In the Kirby-Bauer method, the inoculum must conform to a __ McFarland standard.

0.5

The Mueller-Hinton agar must be poured to a depth of __ mm in the Kirby-Bauer method.

4

The diameter of the zone of inhibition is directly proportional to the __ of the antimicrobial agent.

effectiveness

Penicillin was discovered in 1928 by __ Fleming.

Alexander

Each year in the U.S., at least __ people die due to infections caused by antibiotic-resistant bacteria.

23,000

The CDC estimates approximately __ Americans (48 million) get sick from food-borne illnesses each year.

1 in 6

Standard Plate (Viable) Counts involve diluting milk samples before calculating __ density.

bacterial

The Standard Plate Count method can be done using the __ plate or spread plate technique.

pour

Aseptically transfer 1 mL of milk to a test tube containing 9 mL of __ to create a dilution.

water

After incubation, identify plates that contain __ colonies for countable results.

30 – 300

The original cell density (OCD) of the milk sample is calculated as colony forming units per __ (CFU/mL).

milliliter

The primary end-product of Homolactic Acid Fermentation is __.

lactic acid

For Alcoholic Fermentation, the end-products are __ and carbon dioxide.

ethanol

The bacteria commonly used for yogurt production include Lactobacillus __ and Streptococcus thermophilus.

bulgaricus

To prepare yogurt, milk sugar (lactose) is hydrolyzed into __ and galactose by lactase.

glucose

If the temperature of the milk goes below __°C, it can be placed in an ice bath.

60

After adding yogurt to the milk, the cup should be placed in an __ for fermentation.

incubator

Yogurt made in the laboratory cannot be __, but yogurt prepared at home can be.

eaten

Food production by microorganisms relates directly to __ metabolism.

fermentative

Fermentation can involve both __ and yeasts (fungi) to produce food types.

bacteria

To make a yogurt starter culture, you need store-bought __.

yogurt

Sourdough starter can be made by following guides available online, such as those provided by __.

microbiologyonline.org

Every aspect of the Kirby-Bauer Method must be __ controlled to provide useful data.

tightly

Dyes are __ agents that inhibit transcription or replication.

-static

Formaldehyde is an __ agent that denatures proteins.

aldehyde

Ethylene oxide is a __ agent that alkylates macromolecules.

gas

Hydrogen peroxide is a __ agent that oxidizes macromolecules.

peroxide

The procedure for yogurt preparation begins with obtaining __ of milk.

8 oz.

After thoroughly spreading the inoculum over the agar surface, incubate the plates for __ hours at 35-37°C.

18-24

In step 5 of the yogurt preparation process, add one __ spoonful of store-bought yogurt.

heaping

Cooling the milk to __°C is necessary before fermentation starts.

32

Lactic acid produced during yogurt fermentation causes the milk protein (casein) to __.

curdle

The result of a milk sample with 61 colonies at the 1:10 dilution is calculated as __ CFU/mL.

610

The caloric density for food products is monitored by public health authorities to ensure safety, as foodborne illness can lead to __.

hospitalization

Filtration is used on liquids that cannot tolerate even mild __.

heating

Chlorine and iodine are examples of halogens, which are __ agents.

-cidal

The method of disinfection through gentle heating is known as __.

pasteurization

Radioactive contamination of foods is a concern due to the use of __ radiation.

ionizing

The minimum effective temperature for the Pasteurization method is __°C for 30 minutes.

62.9