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Food safety is paramount. For a responsible food company, having a standard-compliant cleanroom is like donning a "golden armor" for its products.

However, this "armor" isn't a monolithic structure. Instead, it's scientifically divided into different zones based on production processes and hygiene requirements, with layers of protection to precisely filter risks.

 Core Principle: Why Zoning is Essential? 

The core purpose of cleanroom zoning is singular: to control contamination and prevent cross-contamination.

Contamination sources mainly come from three aspects: people, machines, materials, methods, and environment. By physically isolating areas with different cleanliness requirements and coordinating different pressure differentials, airflow organization, and personnel purification procedures, a unidirectional contamination control gradient can be formed from low-cleanliness to high-cleanliness areas, ensuring a high level of cleanliness in the core production areas.

 Four Core Functional Areas of a Cleanroom 

Typically, a standard food cleanroom is divided into the following four main areas from the inside out, with cleanliness requirements decreasing sequentially.

1. Core Production Area (Clean Zone)

Function: This is the area where products are directly exposed to the environment, including processes such as ingredient preparation, mixing, filling, inner packaging, cooling, final cooling of semi-finished products for perishable foods, and temporary storage after disinfection of inner packaging materials. This is the "heart" area with the highest hygiene requirements.

Cleanliness Level: Typically requires Class 10,000 or higher. For certain special foods, some processes even require localized purification down to Class 100.

Management Requirements: Personnel must undergo the strictest first and second changing procedures before entering. Materials are introduced through a pass-through window after disinfection. This area maintains positive pressure to prevent backflow of air from lower-level areas.

2. Semi-Clean Area (Buffer Zone)

Function: This is the "buffer zone" before entering the clean area, a purification preparation area for personnel and materials before entering the core area. It mainly includes: changing rooms, air showers, handwashing and disinfection rooms, material buffer rooms, and equipment cleaning and disinfection rooms.

Cleanliness Level: Cleanliness requirements are lower than the core area but higher than general areas, typically Class 100,000 or Class 300,000.

Management Requirements: In this area, personnel complete key steps such as changing shoes, putting on cleanroom garments, and washing and disinfecting hands. Materials undergo pre-treatment here, including removing outer packaging and wiping and disinfecting surfaces. This area serves as a crucial "filter."

3. General Work Area (Non-Clean Area)

Function: Areas where products are not directly exposed or only undergo simple primary processing. Examples include: raw material warehouses, outer packaging areas, finished product warehouses, testing laboratories (partial), equipment maintenance rooms, and office areas.

Cleanliness Level: No strict air cleanliness requirements, but good environmental hygiene must still be maintained, complying with basic food factory hygiene standards (e.g., GB 14881).

Management Requirements: Personnel do not need to undergo complex changing procedures, but must wear work clothes and maintain personal hygiene. Access control must be installed between this area and the semi-clean area for physical isolation.

4. Auxiliary Area

Function: Areas that provide power and support to the cleanroom. Although not directly involved in production, they are crucial. Includes: air conditioning room, water treatment system, changing rooms, restrooms, and sanitary ware rooms.

Management Requirements: These areas require regular maintenance to ensure stable operation. Restrooms and sanitary ware rooms, in particular, must be strictly managed; their doors must never open directly towards the clean area.

 Dynamic Defense Line: Intelligent Design of Personnel and Material Flow 

Static zoning alone is insufficient; dynamic personnel and material flow route design is the soul of zoning.

Personnel Flow Route: Must follow the unidirectional flow principle of "low clean area → high clean area".

Correct Route: General Area → Shoe Change → First Changing Room (Removing Outerwear) → Second Changing Room (Putting on Cleanroom Gown, Handwashing and Disinfecting) → Air Shower → Core Clean Area.

Absolutely Prohibited: When returning from a high clean area to a low clean area, the same route must not be used; a dedicated passage must be designed to avoid cross-contamination.

Material Flow Route: Raw Materials → Unpacking and Preliminary Processing (General Area) → Through Material Transfer Window (after Disinfection/Wiping) → Buffer Room → Core Clean Area.

Finished Products flow out in the opposite direction, but separately from the raw material flow to avoid cross-contamination.

The zoned management of cleanrooms in food factories is a comprehensive art that integrates architecture, aerodynamics, microbiology, and food processing. Every wall, every pass-through window, and every air shower represents a solemn commitment to food safety for consumers.

Understanding this knowledge not only helps food industry professionals better implement regulations but also gives every consumer greater peace of mind and confidence in the food we consume. Because true deliciousness stems from the utmost respect and protection for detail.