7. Sanitizing and Sanitizers Flashcards
1
Q
Definition of disinfectant
A
- Chemicals that kill bacteria, fungi, viruses, mycobacteria, M. tuberculosis, spores, sterilants or any combination thereof
- Various levels (low, itmd, high) categorized by efficacy levels and intended use
- Efficacy of disinfectants based on statistical significance of killing test bacteria on carriers (59/60 test tubes - for growth)
2
Q
What are sterilant
A
- Destroy/eliminate all types of microbes, including bacterial spores
- Must demonstrate absence of growth in test samples, or 99.9999% (6 log) reduction
- Include specialized chemicals (glutaraldehyde, formaldehyde, peroxyacetic acid)
- Dry heat and moist heat are also considered sterilants
3
Q
What are sanitizers
A
- Chemical agents that reduce, but DO NOT NEC ELIMINATE no of microbes on surface
- Ordinarily used by food processing, handling, prep and service industries
- Two types used in food ind: food contact, non-food contact
4
Q
Disinfectant claims in sanitizers
A
- Food contact sanitizers w/ disinfectant claims
Reduce microbial contamination of specific bacteria by 5 logs in 30 seconds at 20C - Food contact sanitizers w/ no disinfectant claims
May reduce bacteria by 99.9% (3logs) within 5 mins - Non-food contact sanitizers
Reduce bacteria by 99.9% (3logs) within 5 mins at rtp (20-22C)
5
Q
Methods of disinfection
A
- Heat
- UV
- Ozone
6
Q
Disinfection by heat
A
- Steam: 76.7C 15 mins or 93.3C 5 mins
- Hot water: circulation of hot water 85C 20 mins
7
Q
Disinfection by UV
A
- UV light at 253.7nm
- Effective against airborne bacteria, esp mold spores
- Less effective on food (affected by air turbidity)
- Intensity of UV lamp inspected every 6 months, when down to 50% should be replaced
- UV sources should be covered, may damage eyes and skin
8
Q
Disinfection by ozone
A
- produced by ozone generator
- Effective against microbes in cool water and in recirculation water system
- kills spores at 35C
- not effective for food (req higher gas conc > dangerous > oxidation of food > rancid)
- limited solubility and vaporize rapidly at rtp
- breakdown rapidly in water, low residual effect
9
Q
What is the Chambers test
A
- Sanitizer efficiency test
- 99.9999% (5 log) kill of 75-125 mil E. coli and S. aureus within 30 secs at 20C
10
Q
Sanitizers in food contact surfaces
A
- Halogen releasing agents (HRA) e.g. chlorine, chlorine dioxide/mixture of oxychloro compounds, iodophors
- Quaternary ammonium compounds (Quats/QACs)
- Acid-anionic sanitizers
- Carboxylic acid sanitizers
- Peroxy acid compounds
11
Q
Antimicrobial mechanism of HOCl
A
- Inhibit glucose oxidation by certain enzymes (mainly aldolase)
- Disturb protein synthesis
- Oxidative decarboxylation of AA to nitrile and aldehyde
- Reacts w/ nucleic acid, purine and pyrimidine
- Imbalance metabolism: destruction of key enzymes
- Induction of DNA damage, followed by loss of DNA transformation ability
- Inhibit O2 intake and in combination w/ oxidative phosporylation causes leakage of some macromolecules
- Cuases chromosomal alteration
12
Q
Example of chlorine compounds
A
- Hypochlorite (faster killing fx)
- Cl2 gas (water supply, leaves residues)
- CTSP ( expensive, 4% chlorine)
- Chloramine (exp, less irritating, flower killing fx than hypochlorite)
- Chlorine dioxide (not affected by alkaline and organic materials, suitable for WWT)
- Derivatives of isocianuric acids
- Dichlorodimethyl hidatoin
13
Q
Adv and disadv of chlorine compounsd
A
ADV
- broad spectrum
- hard water tolerant
- low temp efficacy
- Relatively expensive
- Non residual activity
DISADV
- Potential for toxic gas formation
- Corrosive
- Irritable
- Unstable, short shelf life
14
Q
What are iodophores
A
- combination of nonionic wetting agent and iodine (iodine + surfactant + acid)
- max antibacterial activity pH 3, min pH 7
- max conc 25 ppm
- Not effective against spores
- Doesnt cause skin irritation at rec conc
- Darkening color of starchy foods
- more expensive
- not stable at temp > 49-60C
- applicable to dairy and beer industries
15
Q
Advantages of iodophors
A
- Stable,long shelf life
- Active against all microbes, except bacterial spores
- 25 ppm to pass Chambers test in 30 sec
- More effective against some virus
- Not affected by water hardness
- Noncorrosive, non irritating
- Good penetration
- Do not form spot / stain
- Amber color when active
- Less reaction with organic matters
16
Q
What are quaternary ammonium compounds
A
- Effectiveness selective to certain type of bacteria (LAB, NOT for E coli and pseudomonas)
- Residual antimicrobial film prevents growth of mold and other microbes
- heat stable
- Effective at wide range of pH (most effective: slightly alkaline)
- noncorrosive and non irritating
- tasteless and odorless
- less affected by organic matter than chlorine
- for floors, walls NOT FOOD CONTACT SURFACES
- 200ppm for hand dip
- germicidal activity: enzyme inhibition + leakage of cell materials
17
Q
What are peroxy compounds
A
- hydrogen peroxide (H2O2) + carboxylic acid
- low foam, no residues
- generally non corrosive to stainless steel and aluminum
- Active over a broad range of pH up to 7,5
- Effective against bacteria (listeria and salmonella), yeasts (candida, saccharomyces, hansenula), molds (penicillium, aspergillus, mucor, geotrichum)
- minimally affected by hard water
- satisfactory activity in cold water
- less affected by organic material than chlorine
18
Q
NaOH peroxy compound
A
- 5%, replaces 500 ppm Na hypochlorite
- Inactivate anthrax spores on equipment
- only in emergencies
19
Q
Br-Cl combination peroxy compound
A
- more effective than chlorine
- used in WATER TREATMENT
- inorganic: chlorinated trisodium phosphate (CTSP)
- organic: sodium dichloroisosianuric
20
Q
Other chemical disinfectants
A
- alcohols (effective at 60-70%, broad spectrum against vegetative bacteria, virus and fungi, more exp since req higher conc)
- aldehydes
- bisphenol
- biguanide
21
Q
disinfectants and their modes of action
A
- Halogen releasing agents
halogenation/oxidation on nucleic acids/proteins - QACs
electrostatic (ionic interaction) against CSM, enzymes proteins - Peroxygens
Oxidation agsinst lipids, proteins, DNA - Alcohols
Protein denaturation against CSM - Aldehydes
Alkylation against cell wall - Bisphenol
Penetration.partition of phospholipid bilayer - Biguanides
Electrostatic interaction against CSM (bacteria) or plasma membrane (yeast)
22
Q
Application of sanitizers
A
- close sircuit/pumped (CIP)
- Soaking small equipments, 2 mins
- Brushing
- Fogging for closed containers (5 minutes, 2x general conc)
- Spraying for wide open surfaces (2x general conc)
23
Q
General recommendation for sanitizers based on microbe
A
- Bacterial spore: chlorine
- Bacteriophage: chlorine, acid-anionic
- Coliforms: hypochlorite, iodophor
- Salmonella: hypochlorite, iodophor
- Gram - psycrotroph: chlorine
- Gram + psycrotroph: QAC, iodophor, chlorine
- Virus: chlorine, iodophor, acid anionic
24
Q
General recommendation for sanitizers based on equipment
A
- Aluminum: iodophor, QAC
- Fogging: chlorine, iodophor, QAC
- Hand sanitation: iodophor
- Equipment (used): iodophore, chlorine
- Equipment (stored): QAC
- Wall: QAC, chlorine
- Porous and white surface: chlorine QAC
