How Do You Validate Dry Sanitation? Deann Akins-Lewenthal, Ph.D. & Bala Kottapalli, Ph.D.
Sanitation Importance • Important topic due to recent recalls involving low-water activity ingredients and products • Big question for industry – How to validate dry sanitation practices so that information can be used to assess efficacy of the sanitation but provide a scientific basis for microbiological lot separation?
Why worry about dry environments? • Pathogens Persist – In low-moisture foods and in dry environments Minimal a w levels required for growth of foodborne microorganisms at 25 ° C Group of Microorganisms Minimal a w required Most bacteria 0.91-0.88 Most yeasts 0.88 Molds 0.80 Halophilic bacteria 0.75 Xerotolerant molds 0.71 Xerophilic molds & osmophilic yeasts 0.62-0.60 Food Microbiology, 2 nd Edition • Water activity is a key driver for choice of cleaning methods.
Effect of A w on the Choice of Cleaning Methods Product Typical Aw Typical Cleaning Method Powdered Soft Drinks 0.20 Dry Cleaning Baked snacks 0.30 Dry Cleaning post oven Vegetable Oils 0.35-0.4 Dry Cleaning or wet cleaning with complete dry out Cereal 0.60-0.70 Dry Cleaning post heat step Meat products 0.95-0.98 Wet Cleaning
Purpose of Cleaning and Sanitation • Remove all residues – Residues will provide harborage for bacterial growth which may influence the safety and quality of food – Excessive soil build-up can be detrimental to processes that involve heat transfer (Alvarez, 2009) • Cleaning vs. Sanitation – Cleaning is the complete removal of food soil typically using appropriate detergent chemicals under recommended conditions – Sanitation refers to the reduction of microorganisms to levels considered safe from a public health viewpoint
Methods of Sanitation • Dry Sanitation – Principles: Removal of soil to a safe, acceptable and functional level with little or no water application – Considerations: necessity for dry cleaning, frequency, define ‘clean’, indicators to measure efficacy, sanitary design, safety, and tools and equipment required to perform the job • Wet Sanitation – Principles: Use of water systems with combination of pressure for removing soil or residues. Wet cleaning will utilize a series of rinses (pre-detergent rinse / Post detergent rinse). A sanitizing treatment is applied after the detergent application, and post detergent rinse to reduce, or eliminate any remaining microorganisms after cleaning – Considerations: necessity for wet cleaning, frequency, choice of detergents & sanitizers, indicators to measure efficacy, sanitary design, safety, and tools and equipment required to perform the job 7
Why Dry Clean • Typical dry manufacturing facilities do not have floor drains, or the floor drains are not adequately located by the equipment • Floors in Dry manufacturing facilities are not sloped to the few existing drains. • Not all electrical panels and electrical services are protected properly against water (waterproof/watertight) • Some materials used in the design and fabrication of the production equipment is not made of non-corroding material • Food contact equipment surfaces are not compatible with water (ex: cloth belts) • Equipment does not have self-draining surfaces • Safety issues (man hours)
Why Dry Clean? • Introduction of water to the equipment or environment provides water for growth. – Food + Water + Time= Microorganism Growth • If wet washing is utilized, all water must be drained and the system completely dried and sanitized. Dry needs to stay dry!
Dry Cleaning Challenges • Wide variety of soils to clean – Tenacious or loose • Sanitary Design of Equipment – Different surface types • Dry Sanitation requires a different set of tools than wet sanitation • Labor Intensive and Slow – Good Training program
Sanitary Design Principles • Cleanable to a microbiological level
Sanitary Design Principles • Accessible, smooth surfaces for Inspection, Maintenance, Cleaning and Sanitation
Sanitary Design Principles • Must be made with compatible materials
No Niches • All parts of the equipment shall be free of niches such as pits, cracks, corrosion, recesses, open seams, gaps, lap seams, protruding ledges, inside threads, bolt rivets and dead ends • All welds must be continuous and fully penetrating
Sanitary Design Principles • Sealed framework
Dry Sanitation Validation • Cleaning: Removing soil till visibly clean • Sanitizing: Reducing microorganisms to levels considered safe from a public health viewpoint – Understand acceptance criteria – Proposed Steps in understanding acceptance criteria • Develop a dry sanitation protocol • Develop a pre-op checklist • Swabbing Protocol • Action levels similar to Wet Sanitation for initial trials • Develop baseline data and implement a process control approach • Verification Methods – Identify, Prove, Document Efficacy • Run Multiple Trials – Demonstrate Repeatability
7 Steps of Dry Cleaning & Sanitation 1. Sanitation Preparation – Purge all systems – Assemble cleaning equipment 2. Secure & Disassemble Equipment – Lock Out-Tag Out (LOTO) – remove guards, release belt tension from conveyors, remove parts, disassemble all components
7 Steps of Dry Sanitation 3. Dry Clean – Scrape, brush down, vacuum and air blow, dry ice cleaning, steam cleaning – Use systemic approach- Top down cleaning – Sweep, remove, empty and clean trash • If equipment has spouts, pigs can be used to remove product.
7 Steps of Dry Sanitation 4. Detail Cleaning – Hand scrape any surfaces with residual product – Wipe down equipment as necessary – Clean framework – Identify and spot clean problem areas
7 Steps of Dry Sanitation 5. Post Inspection & Re-clean – LOTO, inspect for visually clean 6. Pre-Operational Inspection – Correct any deficiencies, reassemble equipment, remove LOTO 7. Sanitize & Release – Document corrective actions, release for production – Alcohol based quats- i.e . Alpet, BioMist • Dries very fast after application
Case Study- Bars • Plant with both dry and wet sanitation • Wet Sanitation – slurry systems, mixers, packaging conveyors, extrusion and coating kettles – Process • Removal of material residues using hot water (130-160 °F), • Scrubbing the equipment using chlorinated foam cleaner • Water rinsing • Applying 200-400 part per million (ppm) of sanitizer to the cleaned areas
Dry Sanitation Methods • Dry Sanitation: Bar Packaging Area – Removing material residues from equipment using compressed air – Cleaning equipment framework and side rails of wrapper using steam machines – Wiping down all equipment framework with 200-400 ppm sanitizer (ready-to-use alcohol based sanitizer)
Dry Sanitation Methods • Dry Sanitation: Cooling tunnels and metal detectors – Involves cleaning the equipment by hand with minimal use of water. – This method requires compressed air to remove material residues on the equipment – Application of 200-400 ppm sanitizer to wipe down equipment framework and rollers – Run belts sequentially through towel with chlorinated cleaner, towel with water, and mist with sanitizer.
Statistical Difference • Purpose of this analysis was to compare if sanitation effectiveness significantly differs between dry and wet sanitation methods.
Results Comparison of APC data between Dry Sanitation and Wet Sanitation Mean APC <100 100-1000 >1000 Comparison* (Log) CFU/Swab CFU/Swab CFU/Swab Dry 1.13 228 (96%) 8 (3%) 1 (1%) a Wet 1.19 1697 (93%) 98 (5%) 38 (2%) a *p-value=0.1169 Based on statistical analysis, there was no statistical significant (p>0.05) difference in APC counts between dry sanitation and wet sanitation
Case Study-Flour • Dry cleaning: Sifter and Cyclone – Involves dry cleaning/sanitation, no water used – Brushing and air blowing to remove residual flour – Visual inspection • Sanitizer – Application of alcohol based sanitizer
Case Study- Flour
Key Reminders When Validating • Perform multiple cleaning/sanitation trials across different production days – Varies based on product susceptibility and equipment type – Understand variation across different runs – If sanitation procedures change significantly, Re- validate • Once data has been collected showing sanitation is effective in reducing microbial populations, the process needs to be verified – Sanitation Effectiveness Program
Sanitation Effectiveness Program • Purpose: Demonstrate effectiveness of the sanitation program on food processing equipment and the production environment using – Physical inspections – Microbiological analysis (Clean Equipment Swab Program) – Documentation of cleaning parameters at set frequencies
Clean Equipment Swab Program • Program should document – Type of testing, location, frequency – Cover entire processing line – Dictate when swabs should be taken in the cleaning/sanitation process • Target and action levels should be determined with corrective actions taken once levels are exceeded
Thank You • Bala Kottapalli • Tony Petersen
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