How to Purify a Sterile Food Processing Workshop

I. Workshop Infrastructure and Purification

1.Selection of Enclosure Materials

Walls and ceilings utilize food-grade, factory-made antibacterial color-coated steel panels; floors feature epoxy self-leveling coating or PVC cleanroom flooring. All wall and floor corners are coved (R50 radius) to eliminate crevices or dead zones, facilitating easy washing and disinfection. Panel joints and gaps where utilities penetrate walls are sealed with food-grade, anti-mold sealant to prevent dust accumulation and bacterial growth. Outward-opening windows are prohibited in clean zones; observation windows consist of sealed, double-glazed units.

2.Zoning and Pressure Differential Control

Workshop zoning: General Processing Area → Semi-clean Area → Sterile Core Area; buffer rooms and airlocks are installed between zones.

The sterile zone maintains a positive pressure of +10–15 Pa relative to the corridor; clean zones maintain a pressure 5–10 Pa higher than general areas, ensuring unidirectional airflow from cleaner to less clean zones and preventing the backflow of contaminated outside air. Raw and cooked product areas utilize independent ventilation systems, with strictly prohibited air exchange between them.

Materials enter clean zones via interlocking pass-through boxes; personnel enter the workshop in stages—passing through primary changing, secondary changing, buffer, and air shower rooms—with completely separate pathways for personnel and materials.

II. Air Purification System

1. Three-Stage Air Filtration System

Fresh air passes sequentially through: Primary Filter (G4) → Medium-Efficiency Filter (F8) → Terminal High-Efficiency HEPA Filter (H13). The HEPA filter achieves ≥99.97% efficiency in filtering 0.3μm particles, effectively removing airborne bacteria and mold spores. Repackaging of general food products: Air exchange rate ≥ 15 times/hour;

Cooked foods and aseptic filling: Air exchange rate ≥ 25 times/hour;

Infant/toddler foods and aseptic cold filling: Install Fan Filter Units (FFUs) above filling points to achieve localized Class 100 unidirectional laminar airflow.

2. Temperature and humidity control to inhibit microbial growth

Standard parameters: Temperature 18–24°C, relative humidity 45–60%; humidity consistently >65% promotes rapid mold growth; dehumidification modules are installed; workshop HVAC ducts are made of stainless steel to prevent dust accumulation on inner walls from contaminating the air supply.

III. Personnel Purification

1.First changing room: Remove street clothes; put on clean undergarments and dedicated clean-room shoes;

2.Second changing room: Put on hairnet, face mask, and clean-room jumpsuit; ensure all hair and facial hair is fully covered;

3.Buffer room: Perform 7-step hand-washing procedure; sanitize hands with 75% alcohol;

4.Air shower room: Air blast for 10–15 seconds to remove hair and skin dander from clothing surfaces; entry into the aseptic workshop is permitted only after the air shower cycle completes;

5.Management requirements: Jewelry and cosmetics are prohibited inside the workshop; work uniforms must have no exposed fibers; uniforms for inside and outside use are washed and sterilized separately; the full sanitization process must be repeated after using the restroom.

IV. Material and Equipment Purification

1.Raw materials and packaging materials

Outer packaging is wiped and sanitized in the outer packaging removal room; inner packaging enters via a pass-through box and is exposed to UV irradiation for 30 minutes; liquid raw materials are transferred via sealed piping to minimize open exposure.

2.Production equipment cleaning

Equipment is constructed from 304 or 316 stainless steel with polished surfaces, free of crevices or dead zones; disassembled and cleaned daily after production; food-grade alkaline cleaners are used for daily cleaning; disinfectants (peracetic acid, hydrogen peroxide, quaternary ammonium salts) are rotated periodically to prevent bacterial resistance; equipment bases and areas beneath piping are wiped and sanitized regularly.

V. Routine Disinfection Plan for the Spatial Environment

1.Routine Static Disinfection

During non-production night shifts: Irradiate the air and environment with UV germicidal lamps for 30–60 minutes; position UV lamps in corners, beneath equipment, and in concealed areas near the ceiling.

Weekly (1–2 times): Sterilize the entire workshop space using hydrogen peroxide mist fumigation to eliminate airborne and surface-adhered bacteria.

Floors and walls: Wipe daily with food-grade disinfectant; keep drainage channels unobstructed and equip outlets with rodent and insect barriers.

2.Cleaning sequence: Follow a top-to-bottom and inside-out approach—start with ceilings and walls, proceed to equipment, and finish with the floors.

VI. Periodic Testing and Maintenance

1.Filter maintenance: Replace primary filters every 1–3 months and medium-efficiency filters every 6–8 months; conduct PAO leak testing on high-efficiency (HEPA) filters every six months and replace them every two years.

2.Environmental monitoring: Periodically test for airborne particles, settling bacteria, and airborne (planktonic) bacteria.

Class 100,000 areas: Settling bacteria ≤ 10 CFU/dish; Class 10,000 areas: Settling bacteria ≤ 3 CFU/dish.

3.Maintain daily records of pressure differentials, temperature and humidity, disinfection activities, and filter operation for inspection by market regulatory authorities.