Since just before the turn of the century, the majority of the food and beverage industry has faced increased scrutiny, aimed at ensuring the safety of the food supply from farm or factory to the consumer's table.
Various factors have contributed to this, including outbreaks of foodborne illnesses, concerns about bioterrorism, and the need to close loopholes, among other reasons.
These regulations have often aligned food safety procedures with those governing the pharmaceutical sector, particularly in terms of mandating the implementation and documentation of Good Manufacturing Practices (cGMP).
One of the most impactful pieces of food safety legislation is the Food Safety Modernization Act (FSMA), which came into effect in 2011.
This act is a significant federal legislation addressing food safety since the Federal Food, Drug, and Cosmetic Act of 1938 amendment by the FSMA.
Given the notable advancements in scientific understanding, particularly in microbiology and food safety, since the early 20th century, many would argue that this update was long overdue.
At the core of this comprehensive legislation lies the objective of achieving the utmost cleanliness of food and its components throughout the entirety of the food supply chain. This effort is intended to foster public confidence in the safety of the food.
Image Credit: Astro Pak Corporation
The primary tool for preventing contamination throughout the food supply chain is Hazard Analysis and Risk-Based Preventive Controls (HARPC), also referred to as the "Preventive Controls Rule."
HARPC mandates that nearly all food manufacturers, processors, transporters, and storage facilities must:
- Identify food safety and adulteration hazards associated with their foods and processes
- Implement controls to minimize those hazards
- Verify that the controls are working
- Design and implement corrective actions to address any deviations from the controls that might arise over time from the food safety plans
Alongside concerns about contamination from foreign substances, undisclosed ingredients, or agricultural residue, a critical consideration should be to prevent inadvertent contamination from the surfaces of machinery used in food processing.
Cleanliness is Critical
Manufacturing systems, components, and equipment play a crucial role in modern food production. Even seemingly "basic" foods like milk, whole grains, nuts, fruits, and vegetables typically undergo some level of processing and packaging. Every stage of preparing these food items for eventual sale requires food-grade cleanliness.
The necessary level of cleanliness for each step varies based on its position in the production process and the potential risk to the final product.
While initial steps might only need visible surface cleanliness, later stages often demand more than that. Continuous bacterial checks or tests to measure surface residues might be necessary to ensure a high-quality production environment.
In some situations, the cleaning process itself can bring about its own set of risks. Alkaline cleansers are generally effective in removing leftover food or organic materials. Cleansers that work well for cleaning and sanitizing often contain chlorine bleach and chlorides.
These cleansers are commonly used due to their cost-effectiveness and efficiency. However, when heat is applied during or after their use, the corrosive nature of chlorine or chlorides can intensify, potentially causing damage to stainless steel.
Stainless steel finds application in food handling because it remains unresponsive to the substances it comes into contact with. This is due to a "passive" layer, about three to four molecular layers thick, which is chemically inert.
Prolonged or repetitive exposure to corrosive substances can breach this layer, exposing the chemically reactive metal beneath. An indication of the compromised state of the steel's passive layer is the appearance of "rouge," a reddish, brownish, or even black accumulation of iron oxides on its surface.
This happens because the free iron within the steel oxidizes (rusts) when reacting with the air or materials passing over it.
At this point, action must be taken to clean, remove rouge, and sanitize the metal to prevent further harm.
The exposed area not only has the potential to contaminate the food being processed, but the corrosion can also lead to surface pitting. This pitting could create openings for biological contaminants, such as bacteria and biofilm, to establish themselves.
Biofilm Buildup. Image Credit: Astro Pak Corporation
Even microscopic roughness is enough to allow bacteria to adhere to a surface. This roughness could be in the form of iron oxide crystals or small cavities in the metal surface that persist even after polishing.
When bacteria stick to a stainless steel surface while water is present, such as in a water purification setup, they produce a slimy layer called a biofilm, composed of an exopolymer. This biofilm acts as a shield for the rapidly growing bacterial community against fluctuations in temperature and chemistry.
These colonies can establish themselves in pipes, filters, storage tanks, and any other surfaces, especially during periods of shutdowns or low water flow. Over time, these communities become harder to eliminate as the biofilm thickens and the genetic composition of the bacteria diversifies.
Due to the exchange of genetic material between different bacterial species, the community can become progressively more resistant to various chemical purification methods. Even flushing the system with water at 80 °C fails to effectively remove well-established, mature biofilm clusters.
While detecting the issue early can significantly mitigate severe scenarios, most monitoring techniques rely on samples from the water flow, which primarily identify free-floating material rather than the firmly attached bacterial community.
While chemical analysis usually yields prompt results for swift problem-solving, current microbial assessments take several days to disclose the extent of contamination. This delay implies that several production batches might already be compromised, potentially even before being shipped out.
Proper surface cleaning is essential for the ongoing and secure operation of stainless-steel equipment. However, it is important to note that surface cleaning alone is insufficient. Complete sterilization is the next step to effectively reduce risks.
Achieving this involves utilizing peroxide blends, ozone, and specific non-chlorinated sterilants. If there has been any physical damage to the surface, whether through corrosion or impact, appropriate measures must be taken to rectify it.
The approach taken for remediation depends on the type, location, and extent of the damage, either through mechanical or chemical means.
It is imperative to consistently maintain and restore the passive layer. This process should occur after any repairs or modifications to the system, ensuring comprehensive protection against chemical reactions.
Known as "passivation," this meticulously controlled chemical treatment targets the interior surfaces. Carefully chosen chemistry and treatment duration are designed to yield optimal outcomes while safeguarding the metal from harm. 316L/304L stainless steel, an alloy composed of chromium, nickel, molybdenum, and iron, is integral to this process.
The iron is chemically eliminated through passivation, giving rise to a chromium-rich metal layer. Over time, the chromium forms a non-reactive chromium oxide film through binding with oxygen in the surrounding air.
The passivation process significantly enhances this film's chromium content beyond what occurs naturally.
Multiple passivation procedures align with FDA guidelines and adhere to cGMP standards. These processes can be documented as part of the HARPC process.
Ultimately, establishing a consistent routine of cleaning, sterilization, and passivation for the surfaces of stainless-steel systems, components, and equipment serves a dual purpose. It ensures compliance with the Food Safety Modernization Act (FSMA) and minimizes the likelihood of production interruptions or product recalls.
This information has been sourced, reviewed and adapted from materials provided by Astro Pak Corporation.
For more information on this source, please visit Astro Pak Corporation.