7. Sanitizing and Sanitizers

Question 1

Definition of disinfectant

Answer 1

• 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)

Question 2

What are sterilant

Answer 2

• 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

Question 3

What are sanitizers

Answer 3

• 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

Question 4

Disinfectant claims in sanitizers

Answer 4

• 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)

Question 5

Methods of disinfection

Answer 5

1. Heat
2. UV
3. Ozone

Question 6

Disinfection by heat

Answer 6

• Steam: 76.7C 15 mins or 93.3C 5 mins
• Hot water: circulation of hot water 85C 20 mins

Question 7

Disinfection by UV

Answer 7

• 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

Question 8

Disinfection by ozone

Answer 8

• 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

Question 9

What is the Chambers test

Answer 9

• Sanitizer efficiency test
• 99.9999% (5 log) kill of 75-125 mil E. coli and S. aureus within 30 secs at 20C

Question 10

Sanitizers in food contact surfaces

Answer 10

• 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

Question 11

Antimicrobial mechanism of HOCl

Answer 11

• 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

Question 12

Example of chlorine compounds

Answer 12

• 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

Question 13

Adv and disadv of chlorine compounsd

Answer 13

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

Question 14

What are iodophores

Answer 14

• 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

Question 15

Advantages of iodophors

Answer 15

• 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

Question 16

What are quaternary ammonium compounds

Answer 16

• 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

Question 17

What are peroxy compounds

Answer 17

• 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

Question 18

NaOH peroxy compound

Answer 18

• 5%, replaces 500 ppm Na hypochlorite
• Inactivate anthrax spores on equipment
• only in emergencies

Question 19

Br-Cl combination peroxy compound

Answer 19

• more effective than chlorine
• used in WATER TREATMENT
• inorganic: chlorinated trisodium phosphate (CTSP)
• organic: sodium dichloroisosianuric

Question 20

Other chemical disinfectants

Answer 20

• alcohols (effective at 60-70%, broad spectrum against vegetative bacteria, virus and fungi, more exp since req higher conc)
• aldehydes
• bisphenol
• biguanide

Question 21

disinfectants and their modes of action

Answer 21

1. Halogen releasing agents
   halogenation/oxidation on nucleic acids/proteins
2. QACs
   electrostatic (ionic interaction) against CSM, enzymes proteins
3. Peroxygens
   Oxidation agsinst lipids, proteins, DNA
4. Alcohols
   Protein denaturation against CSM
5. Aldehydes
   Alkylation against cell wall
6. Bisphenol
   Penetration.partition of phospholipid bilayer
7. Biguanides
   Electrostatic interaction against CSM (bacteria) or plasma membrane (yeast)

Question 22

Application of sanitizers

Answer 22

1. close sircuit/pumped (CIP)
2. Soaking small equipments, 2 mins
3. Brushing
4. Fogging for closed containers (5 minutes, 2x general conc)
5. Spraying for wide open surfaces (2x general conc)

Question 23

General recommendation for sanitizers based on microbe

Answer 23

1. Bacterial spore: chlorine
2. Bacteriophage: chlorine, acid-anionic
3. Coliforms: hypochlorite, iodophor
4. Salmonella: hypochlorite, iodophor
5. Gram - psycrotroph: chlorine
6. Gram + psycrotroph: QAC, iodophor, chlorine
7. Virus: chlorine, iodophor, acid anionic

Question 24

General recommendation for sanitizers based on equipment

Answer 24

1. Aluminum: iodophor, QAC
2. Fogging: chlorine, iodophor, QAC
3. Hand sanitation: iodophor
4. Equipment (used): iodophore, chlorine
5. Equipment (stored): QAC
6. Wall: QAC, chlorine
7. Porous and white surface: chlorine QAC