Food Safety and Environmental Services
Food Equipment Cleaning and Sanitizing: Water Chemistry and Quality (Page 3)
Enzyme-based detergents, which are amended with enzymes such as amylases and other carbohydrate- degrading enzymes, proteases, and lipases, are finding acceptance in specialized food industry applications. The primary advantages of enzyme detergents are that they are more environmentally friendly and often require less energy input (less hot water in cleaning). Uses of most enzyme cleaners are usually limited to unheated surfaces ( e.g., cold-milk surfaces). However, new generation enzyme cleaners (currently under evaluation) are expected to have broader application. Fillers Fillers add bulk or mass, or dilute dangerous detergent formulations which are difficult to handle. Strong alkalis are often diluted with fillers for ease and safety of handling. Water is used in liquid formulations as a filler. Sodium chloride or sodium sulfate are often fillers in powdered detergent formulations.
Additional ingredients added to detergents may include: corrosion inhibitors, glycol ethers, and butylcellosolve (improve oil, grease, and carbon removal).
As with any heat treatment, the effectiveness of thermal sanitizing is dependant upon a number of factors including: initial contamination load, humidity, pH, temperature, and time.
The use of steam as a sanitizing process has limited application. It is generally expensive compared to alternatives, and it is difficult to regulate and monitor contact temperature and time. Further, the byproducts of steam condensation can complicate cleaning operations.
Hot-water sanitizing -- through immersion (small parts, knives, etc.), spray (dishwashers), or circulating systems -- is commonly used. The time required is determined by the temperature of the water. Typical regulatory requirements (Food Code 1995) for use of hot water in dishwashing and utensil sanitizing applications specify: immersion for at least 30 sec. at 77°C (170°F) for manual operations; a final rinse temperature of 74°C (165°F) in single tank, single temperature machines and 82°C (180°F) for other machines. Many state regulations require a utensil surface temperature of 71°C (160°F) as measured by an irreversibly registering temperature indicator in ware washing machines. Recommendations and requirements for hot-water sanitizing in food processing may vary. The Grade A Pasteurized Milk Ordinance specifies a minimum of 77°C (170°F) for 5 min. Other recommendations for processing operations are: 85°C (185°F) for 15 min., or 80°C (176°F) for 20 min. The primary advantages of hot-water sanitization are: relatively inexpensive, easy to apply and readily available, generally effective over a broad range of microorganisms, relatively non-corrosive, and penetrates into cracks and crevices. Hot-water sanitization is a slow process which requires come-up and cool-down time; can have high energy costs; and has certain safety concerns for employees. The process also has the disadvantages of forming or contributing to film formations, and shortening the life of certain equipment or parts thereof (gaskets, etc.).
The ideal chemical sanitizer should:
- be approved for food contact surface application
- have a wide range or scope of activity
- destroy microorganisms rapidly
- be stable under all types of conditions
- be tolerant of a broad range of environmental conditions
- be readily solubilized and possess some detergency
- be low in toxicity and corrosivity
- be inexpensive
The regulatory concerns involved with chemical sanitizers are: antimicrobial activity or efficacy, safety of residues on food contact surfaces, and environmental safety. It is important to follow regulations that apply for each chemical usage situation. The registration of chemical sanitizers and antimicrobial agents for use on food and food product contact surfaces, and on nonproduct contact surfaces, is through the U.S. Environmental Protection Agency (EPA). (Prior to approval and registration, the EPA reviews efficacy and safety data, and product labeling information. The U.S. Food and Drug Administration (FDA) is primarily involved in evaluating residues form sanitizer use which may enter the food supply. Thus, any antimicrobial agent and its maximum usage level for direct use on food or on food product contact surfaces must be approved by the FDA. Approved no-rinse food contact sanitizes and nonproduct contact sanitizers, their formulations and usage levels are listed in the Code of Federal Regulations (21 CFR 178.1010). The U.S. Department of Agriculture (USDA) also maintains lists of antimicrobial compounds (i.e., USDA List of Proprietary Substances and Non Food Product Contact Compounds) which are primarily used in the regulation of meats, poultry, and related products by USDA's Food Safety and Inspection Service (FSIS.).
Factors Affecting Sanitizer Effectiveness
Surface Characteristics. Prior to the sanitization process, all surfaces must be clean and thoroughly rinsed to remove any detergent residue. An unclean surface cannot be sanitized. Since the effectiveness of sanitization requires direct contact with the microorganisms, the surface should be free of cracks, pits, or crevices which can harbor microorganisms. Surfaces which contain biofilms cannot be effectively sanitized. Exposure Time. Generally, the longer time a sanitizer chemical is in contact with the equipment surface, the more effective the sanitization effect; intimate contact is as important as prolonged contact. Temperature. Temperature is also positively related to microbial kill by a chemical sanitizer. Avoid high temperatures (above 55°C [131°F]) because of the corrosive nature of most chemical sanitizers. Concentration. Generally, the activity of a sanitizer increases with increased concentration. However, a leveling off occurs at high concentrations. A common misconception regarding chemicals is that "if a little is good, more is better." Using sanitizer concentrations above recommendations does not sanitize better and, in fact, can be corrosive to equipment and in the long run lead to less cleanable. Follow manufacturer's label instructions. Soil. The presence of organic matter dramatically reduces the activity of sanitizers and may, in fact, totally inactivate them. The adage is "you cannot sanitize an unclean surface."
pH. Sanitizers are dramatically affected by the pH of the solution. Many chlorine sanitizers, for example, are almost ineffective at pH values above 7.5. Water properties. Certain sanitizers are markedly affected by impurities in the water. Inactivators. Organic and/or inorganic inactivators may react chemically with sanitizers giving rise to non-germicidal products. Some of these inactivators are present in detergent residue. Thus, it is important that surfaces be rinsed prior to sanitization.
The microbiological load can affect sanitizer activity. Also, the type of microorganism present is important. Spores are more resistant than vegetative cells. Certain sanitizers are more active against gram positive than gram negative microorganisms, and vice versa. Sanitizers also vary in their effectiveness against yeasts, molds, fungi, and viruses.
Specific Types of Chemical Sanitizers
The chemicals described here are those approved by FDA for use as no-rinse, food-contact surface sanitizers. In food-handling operations, these are used as rinses, sprayed onto surfaces, or circulated through equipment in CIP operations. In certain applications the chemicals are foamed on a surface or fogged into the air to reduce airborne contamination.
Food Equipment Cleaning and Sanitizing Continued: Water Chemistry and Quality Page 4