In the food processing process, air, as an indispensable environmental element, its cleanliness is directly related to the safety and quality of food. Dust, microorganisms, pollen and other pollutants suspended in the air, once they come into contact with food raw materials or finished products, are very likely to cause food contamination, leading to product deterioration, shortened shelf life, and even health problems for consumers. Medium-efficiency air filters, as key equipment in air purification systems, play an irreplaceable role in the air purification process of food factories with their precise filtration performance, building a “protective wall” at the air level for safe food processing.
I. Core Filtration Performance of Medium-Efficiency Air Filters
Medium-efficiency air filters are air filtration devices with a filtration efficiency of 20% to 80% for particles with a diameter of 1.0 micrometers (μm) or larger, based on ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers) standards. Their filtration capability is greater than primary filters but less than high-efficiency filters, making them the ‘intermediate defense line’ in air purification systems.
From the perspective of filtration principles, medium-efficiency air filters mainly capture pollutants using inertial collision, interception, and diffusion: Inertial collision means larger particles like dust and fibers deviate from the airflow and hit filter fibers; interception means medium-sized particles are trapped as they flow close to the filter fibers; diffusion refers to the random movement (Brownian motion) of smaller particles, causing them to collide with and stick to the fibers, enhancing filtration efficiency for fine particles.
In terms of filter material selection, common materials include glass fiber, synthetic fiber, and non-woven fabric. Synthetic fiber filter materials are popular in food factories due to low airflow resistance, large dust-holding capacity, and long service life. Some filters enhance performance by electrostatic charging, which means giving filter fibers an electric charge that attracts fine particles, improving filtration and maintaining low resistance, which helps reduce energy use in the factory’s ventilation system.
Ii. Core Value of Applying Medium-Efficiency Air Filters in Food Factories
(1) Block the paths of microbial contamination
During the food processing, bacteria, molds, yeasts and other microorganisms in the air are one of the main culprits causing food spoilage and safety risks. For instance, during the cooling process of baked goods such as bread and pastries, if they come into contact with mold spores in the air, it is very likely that mold will grow on their surfaces. If meat products and dairy products are contaminated by bacteria during processing, it may lead to excessive levels of pathogenic bacteria such as Salmonella and Escherichia coli. Medium-efficiency air filters can effectively intercept dust particles carrying microorganisms in the air, significantly reduce the concentration of microorganisms in the workshop, cut off the pollution path of microbial transmission through the air from the source, and create a clean microbial control environment for food processing.
(2) Reduce physical pollution
The requirements for environmental cleanliness in food processing are not only reflected in microbial control but also in the strict management of physical impurities. Dust, fibers, metal shavings and other impurities in the air, if mixed into food, will directly affect the sensory quality of the food and may also cause physical damage to consumers’ mouths and digestive tracts. Medium-efficiency air filters can efficiently filter out such larger particle size physical impurities, ensuring that food is protected from external physical contamination throughout the entire process of processing and packaging, and safeguarding the appearance and food safety of the food.
(3) Protect subsequent purification equipment and production equipment
In the air purification system of food factories, medium-efficiency air filters are usually used as pre-treatment equipment before high-efficiency filters. If the interception of the medium-efficiency filter is lacking, a large amount of particulate matter will directly enter the high-efficiency filter, causing it to clog rapidly, shortening its service life and increasing the cost of equipment replacement. Meanwhile, if pollutants in the air enter the interior of production equipment, it may cause wear and tear of equipment components, frequent malfunctions, and affect production efficiency. Medium-efficiency air filters remove most pollutants through pretreatment, which not only extends the service life of high-efficiency filters, reduces the operation and maintenance costs of the purification system, but also protects the stable operation of production equipment.
(4) Comply with food safety regulations and industry standards
All countries have established strict hygiene standards and regulations for food production, and have put forward clear requirements for the air cleanliness of the food production environment. For instance, the “General Hygienic Specifications for Food Production” (GB 14881-2013) of our country stipulates that food production workshops should, in accordance with the characteristics of the products and the requirements of the production process, take necessary air purification measures to ensure that the production environment meets the requirements of food safety. The application of medium-efficiency air filters is an important means for food factories to meet the above-mentioned regulatory standards. It helps enterprises pass food safety system certifications (such as HACCP, ISO 22000, etc.), enhancing their market competitiveness and brand credibility.
Iii. Typical Application Scenarios of Medium-Efficiency Air Filters in Food Factories
(1) Core processing workshop
The requirements for air cleanliness vary among different types of food processing workshops, but medium-efficiency air filters can all play a significant role. In pastry and candy processing workshops, it can effectively prevent dust and microorganisms from contaminating raw materials and finished products, and avoid products getting damp and moldy. In meat product curing and cutting workshops, it can reduce the spread of bacteria in the air and lower the risk of product deterioration. In the dairy fermentation and filling workshops, a classification purification system is constructed in conjunction with high-efficiency filters to meet the strict requirements of dairy products for microbial control.
(2) Cooling and Packaging Workshop
After food is processed at high temperatures, it is prone to attracting pollutants in the air to adhere during the cooling stage due to temperature changes, while the packaging stage directly affects the sealing and protective effect of the food. In the cooling workshop, medium-efficiency air filters can purify the cooling airflow and prevent the growth of microorganisms on the surface of food. In the packaging workshop, by purifying the air environment, impurities such as dust and fibers are prevented from mixing into the packaging materials or adhering to the surface of the food, ensuring that the packaged food meets hygiene standards and extending the shelf life of the products.
(3) Raw Material and finished Product storage area
During the storage of food raw materials and finished products, if the environmental air cleanliness is insufficient, they are prone to dust contamination and microbial erosion, which can lead to the deterioration of raw materials and the damage of finished products. Installing medium-efficiency air filters in the storage area can improve the air quality of the storage environment, reduce the impact of pollutants on food, ensure the storage safety of raw materials and finished products, and lower the inventory loss of enterprises.
(4) Laboratory and Inspection Area
The laboratories and inspection areas in food factories undertake important tasks such as raw material testing and finished product quality inspection. The air cleanliness of the experimental environment directly affects the accuracy of the test results. The application of medium-efficiency air filters can ensure that samples are not contaminated by pollutants in the air during the inspection process, providing reliable environmental conditions for the testing work and guaranteeing the authenticity and validity of the inspection data.
Iv. Key Precautions for the Application of Medium-Efficiency Air Filters in Food Factories
(1) Scientific selection
Based on the pollution level of the workshop, the cleanliness requirements of the food processing technology, and the air volume parameters of the ventilation system, select a medium-efficiency air filter with appropriate filtration efficiency, air volume range, and filter material type. For instance, workshops with a higher risk of microbial contamination can choose filter materials with electrostatic charging function. For ventilation systems with large air volumes, filters with low resistance and high dust holding capacity should be selected to avoid affecting the ventilation effect of the workshop.
(2) Reasonable installation and layout
The installation quality of medium-efficiency air filters directly affects the filtration effect. During installation, it is necessary to ensure a good seal between the filter and the frame to avoid air leakage. In terms of layout, it should be combined with the air flow organization design of the workshop to ensure that the purified air can evenly cover the entire processing area, with a focus on ensuring the air quality at core processing stations and key operation points. At the same time, the principle of staged filtration in the air purification system should be followed. The medium-efficiency filter should be reasonably placed after the primary filter and before the high-efficiency filter to form a complete purification chain.
(3) Regular maintenance and replacement
During the operation of medium-efficiency air filters, pollutants will gradually accumulate on the filter material, leading to increased air resistance and a decrease in filtration efficiency. Food factories should establish a regular maintenance system. According to the resistance changes of the filters, their usage time and the pollution conditions in the workshop, they should clean or replace them in a timely manner. Under normal circumstances, when the resistance of the filter reaches 1.5 to 2 times the initial resistance, the filter material should be replaced in time to avoid the decline in air quality in the workshop due to filter failure and the risk of food safety. At the same time, the replaced waste filter materials should be treated in accordance with environmental protection requirements to avoid secondary pollution.
(4) Coordinated operation of supporting systems
The filtration effect of medium-efficiency air filters cannot be achieved without the coordinated action of supporting facilities such as ventilation systems and disinfection equipment. Food factories should ensure the normal operation of the ventilation system, maintain a reasonable positive pressure environment in the workshop, and prevent unclean air from the outside from seeping in. For areas with a high risk of microbial contamination, ultraviolet disinfection, ozone disinfection and other equipment can be used in combination to further reduce the microbial content in the air, forming a dual protection system of “filtration + disinfection” to comprehensively ensure the safety of the food processing environment.
V. Industry Application Trends
With the continuous strengthening of food safety supervision and the technological upgrading of the food industry, the application of medium-efficiency air filters in food factories is showing the following trends: First, the filter material technology is constantly innovating. The research and application of new high-efficiency and low-resistance filter materials and antibacterial filter materials will further enhance the filtration performance and hygiene safety of the filters. Second, intelligent operation and maintenance has become mainstream. By installing pressure sensors and intelligent monitoring systems, real-time monitoring of filter resistance and operational status can be achieved, automatically reminding for maintenance and replacement, thereby enhancing operation and maintenance efficiency. Thirdly, the demand for customization is increasing. In response to the particularities of different food processing techniques, filter manufacturers will offer more targeted product solutions to meet the personalized purification needs of enterprises.
In conclusion, medium-efficiency air filters, as the core equipment of the air purification system in food factories, play a crucial role in blocking pollution pathways, ensuring food quality, and meeting regulatory standards. Food enterprises should attach great importance to the selection, installation and operation and maintenance management of medium-efficiency air filters, and build a scientific and complete air purification system in combination with their own production needs, providing a solid environmental guarantee for safe food processing and promoting the healthy and sustainable development of the food industry.
I. Core Filtration Performance of Medium-Efficiency Air Filters
Medium-efficiency air filters are air filtration devices with a filtration efficiency of 20% to 80% for particles with a diameter of 1.0 micrometers (μm) or larger, based on ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers) standards. Their filtration capability is greater than primary filters but less than high-efficiency filters, making them the ‘intermediate defense line’ in air purification systems.
From the perspective of filtration principles, medium-efficiency air filters mainly capture pollutants using inertial collision, interception, and diffusion: Inertial collision means larger particles like dust and fibers deviate from the airflow and hit filter fibers; interception means medium-sized particles are trapped as they flow close to the filter fibers; diffusion refers to the random movement (Brownian motion) of smaller particles, causing them to collide with and stick to the fibers, enhancing filtration efficiency for fine particles.
In terms of filter material selection, common materials include glass fiber, synthetic fiber, and non-woven fabric. Synthetic fiber filter materials are popular in food factories due to low airflow resistance, large dust-holding capacity, and long service life. Some filters enhance performance by electrostatic charging, which means giving filter fibers an electric charge that attracts fine particles, improving filtration and maintaining low resistance, which helps reduce energy use in the factory’s ventilation system.
Ii. Core Value of Applying Medium-Efficiency Air Filters in Food Factories
(1) Block the paths of microbial contamination
During the food processing, bacteria, molds, yeasts and other microorganisms in the air are one of the main culprits causing food spoilage and safety risks. For instance, during the cooling process of baked goods such as bread and pastries, if they come into contact with mold spores in the air, it is very likely that mold will grow on their surfaces. If meat products and dairy products are contaminated by bacteria during processing, it may lead to excessive levels of pathogenic bacteria such as Salmonella and Escherichia coli. Medium-efficiency air filters can effectively intercept dust particles carrying microorganisms in the air, significantly reduce the concentration of microorganisms in the workshop, cut off the pollution path of microbial transmission through the air from the source, and create a clean microbial control environment for food processing.
(2) Reduce physical pollution
The requirements for environmental cleanliness in food processing are not only reflected in microbial control but also in the strict management of physical impurities. Dust, fibers, metal shavings and other impurities in the air, if mixed into food, will directly affect the sensory quality of the food and may also cause physical damage to consumers’ mouths and digestive tracts. Medium-efficiency air filters can efficiently filter out such larger particle size physical impurities, ensuring that food is protected from external physical contamination throughout the entire process of processing and packaging, and safeguarding the appearance and food safety of the food.
(3) Protect subsequent purification equipment and production equipment
In the air purification system of food factories, medium-efficiency air filters are usually used as pre-treatment equipment before high-efficiency filters. If the interception of the medium-efficiency filter is lacking, a large amount of particulate matter will directly enter the high-efficiency filter, causing it to clog rapidly, shortening its service life and increasing the cost of equipment replacement. Meanwhile, if pollutants in the air enter the interior of production equipment, it may cause wear and tear of equipment components, frequent malfunctions, and affect production efficiency. Medium-efficiency air filters remove most pollutants through pretreatment, which not only extends the service life of high-efficiency filters, reduces the operation and maintenance costs of the purification system, but also protects the stable operation of production equipment.
(4) Comply with food safety regulations and industry standards
All countries have established strict hygiene standards and regulations for food production, and have put forward clear requirements for the air cleanliness of the food production environment. For instance, the “General Hygienic Specifications for Food Production” (GB 14881-2013) of our country stipulates that food production workshops should, in accordance with the characteristics of the products and the requirements of the production process, take necessary air purification measures to ensure that the production environment meets the requirements of food safety. The application of medium-efficiency air filters is an important means for food factories to meet the above-mentioned regulatory standards. It helps enterprises pass food safety system certifications (such as HACCP, ISO 22000, etc.), enhancing their market competitiveness and brand credibility.
Iii. Typical Application Scenarios of Medium-Efficiency Air Filters in Food Factories
(1) Core processing workshop
The requirements for air cleanliness vary among different types of food processing workshops, but medium-efficiency air filters can all play a significant role. In pastry and candy processing workshops, it can effectively prevent dust and microorganisms from contaminating raw materials and finished products, and avoid products getting damp and moldy. In meat product curing and cutting workshops, it can reduce the spread of bacteria in the air and lower the risk of product deterioration. In the dairy fermentation and filling workshops, a classification purification system is constructed in conjunction with high-efficiency filters to meet the strict requirements of dairy products for microbial control.
(2) Cooling and Packaging Workshop
After food is processed at high temperatures, it is prone to attracting pollutants in the air to adhere during the cooling stage due to temperature changes, while the packaging stage directly affects the sealing and protective effect of the food. In the cooling workshop, medium-efficiency air filters can purify the cooling airflow and prevent the growth of microorganisms on the surface of food. In the packaging workshop, by purifying the air environment, impurities such as dust and fibers are prevented from mixing into the packaging materials or adhering to the surface of the food, ensuring that the packaged food meets hygiene standards and extending the shelf life of the products.
(3) Raw Material and finished Product storage area
During the storage of food raw materials and finished products, if the environmental air cleanliness is insufficient, they are prone to dust contamination and microbial erosion, which can lead to the deterioration of raw materials and the damage of finished products. Installing medium-efficiency air filters in the storage area can improve the air quality of the storage environment, reduce the impact of pollutants on food, ensure the storage safety of raw materials and finished products, and lower the inventory loss of enterprises.
(4) Laboratory and Inspection Area
The laboratories and inspection areas in food factories undertake important tasks such as raw material testing and finished product quality inspection. The air cleanliness of the experimental environment directly affects the accuracy of the test results. The application of medium-efficiency air filters can ensure that samples are not contaminated by pollutants in the air during the inspection process, providing reliable environmental conditions for the testing work and guaranteeing the authenticity and validity of the inspection data.
Iv. Key Precautions for the Application of Medium-Efficiency Air Filters in Food Factories
(1) Scientific selection
Based on the pollution level of the workshop, the cleanliness requirements of the food processing technology, and the air volume parameters of the ventilation system, select a medium-efficiency air filter with appropriate filtration efficiency, air volume range, and filter material type. For instance, workshops with a higher risk of microbial contamination can choose filter materials with electrostatic charging function. For ventilation systems with large air volumes, filters with low resistance and high dust holding capacity should be selected to avoid affecting the ventilation effect of the workshop.
(2) Reasonable installation and layout
The installation quality of medium-efficiency air filters directly affects the filtration effect. During installation, it is necessary to ensure a good seal between the filter and the frame to avoid air leakage. In terms of layout, it should be combined with the air flow organization design of the workshop to ensure that the purified air can evenly cover the entire processing area, with a focus on ensuring the air quality at core processing stations and key operation points. At the same time, the principle of staged filtration in the air purification system should be followed. The medium-efficiency filter should be reasonably placed after the primary filter and before the high-efficiency filter to form a complete purification chain.
(3) Regular maintenance and replacement
During the operation of medium-efficiency air filters, pollutants will gradually accumulate on the filter material, leading to increased air resistance and a decrease in filtration efficiency. Food factories should establish a regular maintenance system. According to the resistance changes of the filters, their usage time and the pollution conditions in the workshop, they should clean or replace them in a timely manner. Under normal circumstances, when the resistance of the filter reaches 1.5 to 2 times the initial resistance, the filter material should be replaced in time to avoid the decline in air quality in the workshop due to filter failure and the risk of food safety. At the same time, the replaced waste filter materials should be treated in accordance with environmental protection requirements to avoid secondary pollution.
(4) Coordinated operation of supporting systems
The filtration effect of medium-efficiency air filters cannot be achieved without the coordinated action of supporting facilities such as ventilation systems and disinfection equipment. Food factories should ensure the normal operation of the ventilation system, maintain a reasonable positive pressure environment in the workshop, and prevent unclean air from the outside from seeping in. For areas with a high risk of microbial contamination, ultraviolet disinfection, ozone disinfection and other equipment can be used in combination to further reduce the microbial content in the air, forming a dual protection system of “filtration + disinfection” to comprehensively ensure the safety of the food processing environment.
V. Industry Application Trends
With the continuous strengthening of food safety supervision and the technological upgrading of the food industry, the application of medium-efficiency air filters in food factories is showing the following trends: First, the filter material technology is constantly innovating. The research and application of new high-efficiency and low-resistance filter materials and antibacterial filter materials will further enhance the filtration performance and hygiene safety of the filters. Second, intelligent operation and maintenance has become mainstream. By installing pressure sensors and intelligent monitoring systems, real-time monitoring of filter resistance and operational status can be achieved, automatically reminding for maintenance and replacement, thereby enhancing operation and maintenance efficiency. Thirdly, the demand for customization is increasing. In response to the particularities of different food processing techniques, filter manufacturers will offer more targeted product solutions to meet the personalized purification needs of enterprises.
In conclusion, medium-efficiency air filters, as the core equipment of the air purification system in food factories, play a crucial role in blocking pollution pathways, ensuring food quality, and meeting regulatory standards. Food enterprises should attach great importance to the selection, installation and operation and maintenance management of medium-efficiency air filters, and build a scientific and complete air purification system in combination with their own production needs, providing a solid environmental guarantee for safe food processing and promoting the healthy and sustainable development of the food industry.
