The point of sterilizing and washing a knife is to ensure good hygiene and provide safe food. Knives used for cutting meat in processing plants, butchers and abattoirs would need to be washed and sterilized at regular intervals of, at a minimum, once between every carcass. This regular sterilizing avoids cross contamination.

It is common industry practice to also clean and rinse knives at time of sterilization. This often occurs while sterilization occurs (as is the case with traditional hot water systems). Chemical and UV or Ozone type sterilizers require an additional step to clean and rinse.

Types of Sterilizers

As mentioned above there are three primary types of sterilizers that can be used for the sterilization of knives. Chemical sterilizers, UV or Ozone sterilizers or hot water sterilizers.

Chemical Sterilization

Chemical compounds like iodine, ammonium, and chlorine are used for sanitizing equipment and surfaces. However, chemical sterilization for knives is not economical and not common due to cost, regulatory restrictions, and potential risks of corrosion or damage to equipment.

MEFE does not currently offer any chemical sterilizers due to a lack of interest from the market. If you have a need for chemical sterilization please contact info@mefe.com.au and we would be happy to assist.

Autoclave Sterilization

Autoclave sterilization employs steam under pressure to kill harmful microorganisms. Items, including knives, are placed inside a pressure vessel and heated to an appropriate temperature for a specific duration. This method is highly effective in killing bacteria, viruses, fungi, and spores, making it a effective choice in medical industries, However seems to be time consuming and cost inhibitive for the food industry.

MEFE does not currently offer any autoclave sterilizers due to a lack of interest from the market. If you have a need for autoclave sterilization please contact info@mefe.com.au and we would be happy to assist.

UV or Ozone Sterilization

Ozone or UV sterilizers do work and are effective if the knives are washed and rinsed prior to sterilization. UV sterilization utilizes ultraviolet radiation, particularly UVC wavelengths (200 nm to 300 nm), to destroy the DNA structure of microorganisms. This process renders them harmless by inactivating their cellular functions. UV sterilization is fast and efficient, capable of neutralizing a wide range of pathogens within seconds. It is particularly useful for surfaces and equipment that can be exposed to UV light.

Ozone (O3) sterilization involves using ozone gas, which attacks and oxidizes organic matter. This process alters the cellular structure of microorganisms, rendering them inactive. Ozone sterilization is effective in destroying bacteria, viruses, and fungi. It is a powerful disinfectant that can penetrate difficult-to-reach areas.

The requirement to still clean and rinse the knives often precludes these as an option in most cases. If a way to efficiently clean and rinse the knives can be factored into plants process the MEFE Ozone sterilizers listed below offer an interesting alternative to traditional sterilizers on the market.

https://www.mefe.com.au/ozone-sterilizer-double-door/v

https://www.mefe.com.au/ozone-sterilizer-single-door/

Hot Water Sterilization

Hot water sterilization is a simple yet effective method that utilizes heated water to eliminate pathogens. Knives are submerged in clean water maintained at temperatures above 82 degrees Celsius. MEFE recommends targeting 85°C to ensure sterilization is occurring.

The sterilization time varies depending on the level of contamination. Knives with protein or fat residues may require longer sterilization times to ensure complete disinfection. Sterilizing time ranges from 3 seconds to 45 seconds and in slaughter halls and abattoirs it is recommended to use a 2 knife system ensuring every knife has maximum time between carcasses.

Current setups on the market often struggle to provide clean water at adequate temperature in an efficient and cost-effective manner. The MEFE sterilizers have been developed working closely with many large meat producers to tackle this problem.

Flushing water for wash & rinse

To maintain clean water the sterilizer should be constantly flushed. The Sterilizer is flushed by way of placing the inlet of the water supply on the bottom of the sterilizer and the outlet or overflow, at the top. This ensures that all the fats and oils are skimmed off the top of the sterilizer.

Maintaining and controlling temperature

To maintain the 85 degrees needed for sterilization a number of effective and ineffective methods are used.

Steam heated

Steam or hot water from an external boiler may be used. This method may be the largest culprit of water wastage and the reasons will soon become obvious.

As the steam enters the sterilizer it immediately starts to cool, and since the hottest it can be when entering the sterilizer is 100 degrees it is only a relatively short period of time before it is below 85 degrees. To again get it above 85 degrees more steam is needed to bring it back above 85, this results in a constant flow of steam, dependent on the ambient temperature and usage this amount of water that is being used can be astronomical.

Boiler Heated

Larger plants and setups will sometimes use a centralized boiler to pump heated water from a boiler.

The problem here is the flushing of the sterilizer and to overcome this the introduced water is generally needed to be a constant flow, this flow of water is generally way lower as in one above but can still be a huge waste of water.

Electric element heated

The most common method of heating and maintaining the water temperature is via an electric element and thermostat. This is very similar to a standard kettle and when combined with a thermostat will switch on and off as required holding the water temperature above 85 degrees.

Efficiencies

MEFE sterilizers have overcome the mentioned above by employing the following design features.

Control the flow of water introduced

Controlling the flow of flushing water or steam. Generally, this control has been via a valve that is slightly open, or more accurately via a valve and orifice that only allows a measured flow.

The problem here is that the element is flushed on a continuous basis, even if its not being used or with minimal use will encounter the same water wastage as a sterilizer that is in constant use. Water flow and wastage within the sterilizer can be huge.

To effectively and securely control the flush water we advise installing on each sterilizer a simple 6V solenoid valve. 6 Volts as this can easily be wired and controlled from a central point. At the central control point the possibilities become endless as now each sterilizer can be flushed as and when required, as a group in usage, individually when needed, or simply on a timer. The complete system can also be switched off during breaks and between shifts. This will not only save massive amounts of water it will also save huge amounts of power.

Use Insulated sterilizers

Sterilizers should be constructed with double walls and insulation to reduce heat loss and improve energy efficiency. This design helps maintain stable temperatures within the sterilizer, reducing the need for additional heating and minimizing energy consumption.

Use electric element to maintain heat

Equip sterilizers with their own internal electric heating element and thermostat to ensure precise temperature control. Set the thermostat within the range of 82 to 85 degrees Celsius, optimizing energy usage while maintaining effective sterilization conditions.

Centralized Water Supply from Boiler or Heat Exchanger

Introduce a centralized system for flushing and filling clean water into the sterilizer, preferably from a central boiler or heat exchanger. This approach reduces the energy required to heat water individually for each sterilizer, resulting in overall energy savings.

By Employing safety measures such as airgap inputs or non-return valves to prevent contamination of the clean water line and ensure water flows in the desired direction without backflow.

By implementing these energy and water-saving strategies, industries can minimize operational costs, reduce resource consumption, and contribute to sustainability efforts while maintaining effective knife sterilization practices. MEFE has generated a Cost saving calculator to allow for quick and easy comparison of current spending and proposed savings with the controls listed above in place.

The Sterilizer Feature chart provides a reference for all the features available on MEFE hot water sterilizers.

For further information or guidance please contact info@mefe.com.au and we would be happy to assist.