Topic 3 : Sanitation Flashcards
What is the difference between cleaning, sanitising and disinfecting?
Cleaning: Removes dirt and reduces microbes.
<br></br>
Sanitising : kills most microorganisms (MO)** to a safe level** using chemical / physical means and may not target viruses effectively.
Disinfecting : higher level of killing of MO, including viruses
What is the definition of cleaning?
Physical removal of soil and MO in soil, aided by chemical agents.
What are the 3 types of inorganic soil (residues)?
- Hard water deposits, minerals found in water such as calcium and magnesium
- Metallic deposits
- Alkaline deposits
What type of cleaning compound is required to remove inorganic soil (hard water deposit / metallic deposit / alkaline deposit)?
Acid-type cleaner
What are the 3 different types of organic soil and examples?
- Food deposits → food residues
- Petroleum deposits → from lubricating agents/ lubricating oils / grease (for machinery)
- Non-petroleum deposits → animal fats, vegetable oils (lipids), proteins
What kind of cleaning compounds are used to clean non-petroleum deposits (lipids/proteins)?
Alkali-type cleaner
Why can’t acid type cleaning compounds be used for hydrolysing protein deposits, instead of alkaline ones?
Usage of acid type cleaning compounds means pH will be low, making it nearer to the isoelectric point of the proteins. Proteins will thus coagulate and making it harder to remove the deposits.
What are the 3 steps in removing soil (residues) from a surface, and how to achieve it?
- Separate soil from surface using physical / chemical means
<br></br> - Dissolve / disperse soil in cleaning solution → use surfactants to disperse soil as a colloid
<br></br> - Prevent dispersed soil from reattaching to surface → achieved through rinsing
Types of cleaning compounds
What kinds of applications are strong alkaline cleaners used for?
CIP systems, as strong alkaline cleaners are not suited for manual cleaning.
Types of cleaning compounds
What are some examples of weak alkaline cleaners?
Na2CO3, Na3PO4
Note : phosphates are sequestrants too → bind to metal ions
Types of cleaning compounds
What kinds of deposits do cleaners with active chlorine get rid of, and what is their mechanism of action?
Chlorinated cleaners → carbohydrate / protein deposits
<br></br>
Mechanism of action:
- Reacts with polymers to make them shorter chain / more water soluble
- Helps in peptization (process of turning a precipitate into a colloid by mixing it with an electrolyte)
Types of cleaning compounds
Give examples of highly corrosive acidic cleaning compounds, and state their applications [3].
HCl, HF.
<br></br>
Applications:
- removing of minerals and rust (inorganic metals)
- floor maintenance
- brightening of steel surfaces
Note : acidic cleaners react with inorganic metals. Recall : acid + metal → salt + hydrogen
Types of cleaning compounds
Give examples of mildly acidic cleaning compounds, and what are they used for?
Mildly acidic cleaning compounds are typically organic acids such as citric acid.
- They are used for removal of water scales (buildup of dissolved minerals that forms on surfaces that are in contact w water)
Types of cleaning compounds
What are the 3 types of surfactants?
- Cationic surfactants
- Anionic surfactants
- Nonionic surfactants
Types of cleaning compounds
Cationic surfactants are usually used as cleaning agents to clean surfaces. True or False?
False, cationic surfactants are not typically used as cleaning agents, but rather bactericidal sanitisers
Bactericidial = “bacteria” + “suicide” = kill bacteria
Types of cleaning compounds
What are anionic surfactants used for?
Anionic —> attract cations (metal cations)
Types of cleaning compounds
What are non-ionic surfactants used for?
Surface cleaning, as non-ionic surfacants have tendency to form foams which is good for cleaning a wide surface area.
Types of cleaning compounds
How do surfactants work?
- Individual surfactant molecules consist of a hydrophilic head and a hydrophobic tail. In water, surfactant molecules self-assemble into micelles, where hydrophobic groups cluster in the centre.
- The hydrophobic groups attach themselves to the soil / residues, while hydrophilic head interacts with the surrounding water / detergent.
- This reduces surface tension between the soil and the surface, allowing the surfactant to lift and suspend the soil away from the surface.
- The soil particles are trapped inside the micelles, preventing them from reattaching to the cleaned surface.
See diagram in notes
Types of cleaning compounds
Surfactants reduce the surface tension of liquids and this improves cleaning efficiency. What does this mean?
Surfactants reduce the cohesive forces between liquid molecules (e.g. detergent molecules). This allows the detergent to spread more easily across surfaces, increasing the area of contact between the cleaning solution and the surface, which improves cleaning efficiency.
Auxillary agents
What are auxillary agents in cleaning agents?
Auxillary agents are substances that improve the perfomance of a cleaning agent.
Auxillary agents
What is the purpose of chelators / sequestrants? Give some example(s).
Sequestrants prevent precipitation between alkaline cleaning agents and minerals from hard water (Ca2+, Mg2+)
- e.g. : citric acid, phosphonates, EDTA, polyphosphates
Auxillary agents
What are suspending agents and their purpose? Give examples.
They are thickeners that prevent dispersed soil from reattaching back to surfaces
- example : hydrocolloids
Auxillary agents
What are scouring agents?
Abrasives that help to remove soil (physical)
- abrasive powder, like finely ground minerals like pumice, calcium carbonate (chalk), or quartz, which are added to a cleaning solution to physically scrub and remove stubborn dirt from surfaces by creating a scouring action
Auxillary agents
What is the purpose of corrosion inhibitors and what kind of cleaning agents are they found in? Give examples.
Corrosion inhibitors prevent corrosion of surfaces, and can be found in strong or weak acid / alkali cleaners.
- Example : silicates
Sanitisers
What are the 6 factors that affect the effectivness of sanitisers?
- Exposure time (longer time = more effective)
- Temperature (higher temp = more effective BUT some sanitisers are volatile)
- Presence of soil (present = lowered effectiveness as residue/soil can shield microbes)
- pH (affects stability of sanitisers ; and microbial reduction dependent on pH)
- Microbes present (high microbial load reduce effectiveness)
- Presence of biofilms (resuce effectiveness of sanitsers as MOs are more resistant)
Sanitisers
What are the 2 main types of physical sanitation methods?
- Thermal sanitising
- Radiation
Sanitisers
What is used for thermal sanitation?
Hot water / steam
Sanitisers
What are the disadvantages for thermal sanitation? [2]
- Dangerous for manual cleaning
- Steam quickly loses effectiveness when it becomes cold
Sanitisers
Radiation sanitation can be categorised into non-ionising and ionising radiation. What is non-ionising radiation and how does it kill microbes?
Radiation that does not break chemical bonds, through the use of UV light.
It kills microbes by :
- causing pyrimidine (cytosine / thymine) to dimerise
- repair of DNA leads to mutation of microbial cell pr cell death
Sanitisers
What are some examples of ionising radiation in sanitation?
Gamma radiation, X-ray, e-beam (shorter wavelength than UV, higher energy)
Sanitisers
What are the 2 mechanism of action that ionising radiation damage microbial cells?
- Direct damage, by breaking the double stranded helix of DNA and lead to cell death
2.Indirect damage : breaking of chemical bonds causes formation of radicals / reactive oxygen speicies which damages DNA, or causes lipid / protein oxidation, eventually leading to cell death
Sanitisers
What can ionising radiation do to the organoleptic properties of food? What is ionising radiation usually used for?
Formation of free radicals in ionising radiation may change the taste of food. It is usually used for sterilising food packaging.
Sanitisers
What are the disadvantages of using UV radiation? [4]
- Hazard to workers
- Limited penetration depth, easily blocked by soil
- UV lamp may violate glass policy of the plant (no glass in factory)
- Radiation may not be effective (endospores resistant to UV an ionising radiation)
Sanitisers
What are the 5 main mechanisms in which chlorine based sanitisers kill microbes?
- Reacting / oxidising nucleic acids (e.g. DNA)
- Damage chromosomes
- Inhibit oxidative phosphorylation (respiration)
- Disrupt protein synthesis
- Damage chromosomes
Sanitisers
What are iodophors (sanitiser)? Why must they be rinsed off at higher concentrations (i.e. cannot be “no-rinse” at higher conc)
Iodophors are complexes of elemental iodine with a non-ionic surfactant
- need to be rinsed off at higher conc bc iodine is brown and can stain surfaces
Sanitisers
What are the advantages of iodophors over chlorine based disinfectants? [3]
- Less irritating to human skin and mucous membrane
- Stable at low pH
- Less reactive : do not react with other substances, and do not degrade as easily.
Sanitisers
What are some disadvantages of iodophors over chlorine based disinfectant? [3]
- Stronger smell which can contribute to off-flavours
- Stain porous materials
- Less effective in endospore inactivation.
Sanitisers
Quarternary ammonium compounds are what kind of surfactants?
Cationic surfactants
Sanitisers
What are some characteristics of quarternary ammonium compounds? [2]
- Have surfactant properties, foams easily
Forms a thin bacteriostatic residual layer on surface
Sanitisers
What are some advantages of quarternary ammonium compounds? [5]
- Low toxicity, non-corrosive, non-irritating
- Safe, easily removed from skin with anionic detergent (aka soap)
- Colourless, odourless,
- Stable against organic compounds
- Little loss in effectiveness over time (unike chlorine based sanitisers)
Sanitisers
Why shouldn’t you use quartnery ammonium compounds to sanitise fermentation tanks?
The residual film could inhibit growth of bacteria, and fermentation requires bacterial growth.
Sanitisers
Quartnery ammonium compounds are not compatible with which 2 types of cleaning agents?
- anionic detergents
- phosphate sequestrants
Sanitisers
Acid sanitisers are usually available as a mix of which 2 acids?
Phosphoric
Carboxylic
Validation, monitoring, verification of cleaning
What is validation of the cleaning method? In what 4 ways can validation be carried out?
Validation is to prove that the SSOP will be effective in reducing microbial load to a safe level.
<br></br>
Ways to carry out validation:
1. Literature review
2. Field trial (most impt! Irreplaceable!)
3. Regulations
4. Lab tests
Validation, monitoring, verification of cleaning
What are some areas the validation process should cover? [4]
note : non-exhaustive
- Optimum cleaning frequency
- SSOP can clean equipment and environment thoroughly, even difficult to reach areas
3. Establish the achievable level of cleaniliness - Establish frequency of glove change/handwashing/shoe dips
Validation, monitoring, verification of cleaning
What does monitoring mean? At what is the frequency is it done?
Monitoring : ongoing, real-time observation and recording of activities or parameters to ensure that processes are operating within established limits.
- tests that are quick and easy to carry out, done on a daily basis
Validation, monitoring, verification of cleaning
What is verification? At what frequency is it carried out?
Verification is the process of confirming that the monitoring system and SSOP is working effectively.
- carried out on a longer interval basis, once every few months (e.g. audits of cleaning records)
Validation, monitoring, verification of cleaning
ATP monitoring can be used to monitor food. How does it work?
- use a swab to collect a sample from a surface
- insert the swab into a luminometer which measures the amount of ATP present by triggering a chemical reaction that produces light
- intensity of light is directly proportional to the amount of ATP
Validation, monitoring, verification of cleaning
Since ATP is found in microbial cells, ATP monitoring is indicative of microbial contamination. True or False?
False. All organic material, including food (with live cells) contain ATP, as it is the universal energy currency of all cells. Thus, ATP monitoring is only indicative of cleaning effectiveness and not microbial contamination. (Also, food usually contains more ATP than microbes)
Validation, monitoring, verification of cleaning
How does protein monitoring work?
It is based on the principle of BCA (bicinchoninate assay) / Biuret reaction, where Cu2+ is reduced to Cu+ by specific amino acids
Validation, monitoring, verification of cleaning
When testing for microorganisms, what are the 2 main groups of microorganisms that can be tested?
- Indicator organisms (total plate count, Enterobacteriaceae)
- Industry specific pathogens
What should be tested for microbial levels? [2]
- Food contact surfaces
- CIP rinse water
When should samples be collected and tested for microbes? Give the rationale
- Just after cleaning, before sanitising → to ensure all soil is removed before proceeding to sanitising ;; sanitizers may interfere with ATP / protein / allergen assay
<br></br> - Samples can be collected after sanitising → gives assurance for the next run ;; so you know the food processed in the next run would be safe.
What should the sanitation SOP (standard operating procedure) contain?
- Cleaning frequency
- Safety procedures, PPE required
- Lock out / tag out procedures → to ensure equipment is not operating when someone is cleaning it
- Chemical safety procedures (SDS, how to mix cleaning chemicals, first aid measures)
- Disassembly procedure (machinery)
- Cleaning procedure
- Monitoring procedure
- Verification procedure
As a general rule of thumb, how frequent should sanitation occur?
At least once every 24h / every change in product type / every change in allergen type
What are the general steps for a cleaning procedure?
RInse → clean → rinse → sanitise / disinfect → rinse*
*Not all sanitisers need to be rinsied off
Special topic : biofilms
What are biofilms?
A microbial community characterised by its adhesion to a solid surface and by the production of an extracellular polymeric matrix in which MOs are embedded.
Special topic : biofilms
Special topic : biofilms
Special topic : biofilms
Special topic : biofilms
Special topic : biofilms
What 2 factors of surfaces can encourage biofilm formation?
- Rough surfaces (e.g. presence of scratches)
- Hydrophobic surfaces
Special topic : biofilms
Formation of biofilms involve production of polysaccharides by vacteria. How does the microbe know when to start producing these polysaccharides, mate and disperse?
Through quorum sensing, whereby cell to cell communication of bacteria cells allows them to share information about cell density and adjust gene expression accordingly.
What is the general mechanism of quorum sensing?
- Autoinducers (small, diffusible signal molecules) are produced and secreted at a basal level during bacterial growth
- Concentration of singal increases as bacteria population increases
- Bacteria display different phenotypes depending on population density.
example L acylhomoserine lactone (AHL)
AHL is produced at basal level
*
AHL diffuses and is uptake by bacteria through active transport.
*
Above a certain threshold, AHL binds to transcription factors (R proteins). This complex binds to DNA and causes changes in gene transcription
What are some strategies to manage biofilms?
- Thorough cleaning and sanitation
- Surface coatings (hydrophilic) to discourage biofilm formation
- Sanitisers that specifically inhibit quorem sensing?
- Additives that inhibit quorum sensing?
Point 3 and 4 : ongoing research needed
