View
221
Download
4
Category
Tags:
Preview:
Citation preview
9- Control of Microbial Growth
Mechanisms of action (MOA)
membrane
protein
nucleic acid
Factors
number
environment
microbial structure/characteristics
& pseudomonads
Disinfectant evaluation
Phenol coefficient
American official Analytical Chemist’s use-dilution method
In-use test
Disk diffusion test
Heat
standard measures
thermal death point (TDP)
thermal death time (TDT)
Decimal Reduction Time (DRT = D value)
Moist heat
Steam
Autoclave
Pasteurizationtraditional
High-Temperature Short-Time (HTST)
Ultrahigh-Temperature treatment (UHT)
UHT sterilization
Dry heat flaming oven
incineration
Filtration
air: High-efficiency particulate air (HEPA)
liquid: porcelain & glass
paper
membrane
Low temperature
Dessiccation
Osmotic pressure
Electromagnetic radiation (4.1)
Irradiated food
Phenol -> carbolic acid
Lister
eugenol (clove oil)
thymol
pine oil
Isopropyl alcohol = isopropanol
Ethyl alcohol = ethanol
Proof?
tincture iodophor
Halogens
Iodine (I2)
Ca(OCl)2 calcium
hypochlorite
NaOCl sodium hypochlorite
Na dichloroisocyanurate (Chlor-Floc)
chloramine
Halogens
ChlorineChlorine gas (Cl2)
Cl2 + H2O -> HOCl hypochlorous acid
ClO2 chlorine dioxide
Oxidizing agents
Ozone (O3) peracetic acid
Soap has a structure similar to that shown here for one type (sodium stearate). Soap works because it has the ability to interact with nonpolar (oily) substances as well as with water.
In an oil droplet suspended in water, the hydrocarbon residues (R-groups) of soap molecules are immersed in the oil, and the ionic ends extend into the water. Attractive forces between water molecules and the ionic heads cause the oil droplet to be solubilized.
Surfactants= Surface-Acting agents
emulsificationsometimes added: triclosan & triclocarban
What’s the difference?
Antibacterial soap Alcohol gel
(has triclosan)
Use with water Do NOT use water
Scrub 2-3 minutes Wipe on, wipe off
cationic detergents = quaternary-ammonium detergents = (quats)
Oligodynamic action: heavy metals
Ag
Ag
CuAlso: Zn, Hg, As
formaldehydeglutaraldehyde
Aldehydes
ethylene oxide propylene oxide beta-propiolactone
Gaseous chemosterilizers
Food preservativesSO2 = sulfur dioxide (and _____ bisulfite or _____ metabisulfite or _____ sulfite)
benzoic acid/Na benzoatesorbic acid/K sorbateNa nitrite & Na nitrate
Personal caremethylparaben, propylparabenmenthol
crystal/gentian violet
methylene blue
Dyes
Antibiotics (not used for treatment)
nisin natamycin = pimaricin
Other antimicrobials tea tree oil (terpin-4-ol) manuka honey (methylglyoxal)
Recommended