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The benefits of using synthetic fluids and greases in machinery have been demonstrated extensively. They prolong oil service life, reduce downtime (thus increasing productivity), and better protect metal surfaces from corrosion and wear. They can withstand extreme temperatures and can be designed for specialized applications.
Certain synthetic lubricants have an additional benefit for food and beverage manufacturers because new lubricants have been certified as being nontoxic for humans. These food-grade synthetic lubricants have been used commonly by the food and beverage industries overseas, and are now gaining popularity in the United States.
Lubricant contamination has been a problem in the food and beverage processing industry, where a major accident could require a company to make a massive product recall, which could be devastating to its reputation.
Minor lubricant leaks in machinery are common, sometimes unavoidable, and not always obvious. Just the normal wear and tear on seals can cause a gearbox or hydraulic system to leak, releasing minute levels of oil that can come into contact with food. Contamination can also come from drips from chains or a release of compressed air that contains an oily mist.
Good engineering and operational practices can minimize, but not eliminate, these threats. So any food or beverage manufacturer that is not using food-grade lubricants is operating under an unnecessary risk. Some have switched to the exclusive use of food-grade lubricants simply to reduce human error.
If a plant uses a nonfood-grade lubricant, the U.S. Food and Drug Administration (FDA) allows zero amounts of lubricant to come into contact with the food. If the lubricant accidentally comes into contact with food, the batch must be discarded. If the plant uses food-grade lubricants, which are nontoxic, odorless, colorless and tasteless, the FDA limits lubrication contamination to 10 parts per million.
The FDA has specified criteria for the acceptable components used in food-grade lubricants. The U.S. Department of Agriculture formerly approved specific lubricant products for use in the food manufacturing process. Now NSF International maintains the Class H1 list of acceptable lubricants.
The historic practice has been for companies and food safety inspectors to use spot-checks of manufacturing equipment and processes, along with tests of the finished product, to ensure against contamination. However, a newer space-age technology is increasingly impacting the use of lubricants around processed foods and beverages.
The National Aeronautics and Space Administration (NASA) provided a more proactive system when it developed the Hazard Analysis and Critical Control Point (HACCP) system in the 1960s to protect astronauts against food-borne illnesses. HACCP (pronounced “hassip”) uses science-based controls to identify the hazards associated with processing a food and the production points where those risks can be eliminated.
It establishes preventive measures (such as minimum cooking temperatures) for each control point, sets procedures to monitor those points, and prescribes corrective actions to be taken when monitoring shows that a critical limit has not been met. Monitoring devices verify that a system is working properly. Records are kept to document operations.
HACCP has been endorsed by the National Academy of Sciences, the Codex Alimentarius Commission (an international food standard-setting organization), and the National Advisory Committee on Microbiological Criteria for Foods. The FDA has required use of HACCP for some high-risk foods, such as seafood, but is moving to adopt the standards on a wider basis.
One of the most important threats facing the food industry is the increasing number of new pathogens. For example, between 1973 and 1988, bacteria not previously recognized as important causes of food-borne illness - such as Escherichia coli O157:H7 and Salmonella enteritidis - became more widespread. There also is concern about increasing chemical contamination of food, such as the effect of lead in food and water on the nervous system.
Another important factor is that the food industry and its diversity of products and processes have grown tremendously in recent years; both in the volumes of domestic production and imports, while the resources of the FDA and other regulatory agencies have remained static.
Most major food-producing companies have begun using the HACCP system, but their plans don’t always recognize the importance of a lubrication survey.
HACCP surveys form a key point of food safety management systems and should be treated as an ongoing exercise rather than a one-time activity. All lubrication points should be considered critical control points, or areas of potential risk. Food processing generally involves machinery and accessories such as pumps, mixers, tanks, gearboxes, hydraulics, hoses, pipes, drive chains and conveyor belts.
Lubrication critical control point surveys need to focus on whether the properties of the lubricant match the use: if the storage is secure and containers are not leaking; the type and frequency of maintenance; if containers used to dispense the lubricant also are used for other lubricants; if the equipment design permits easy access for lubrication without incidental contact with foods; and if lube recirculating systems are functioning.
Lubrication maintenance of process equipment is often difficult to reconcile with the stringent hygienic requirements imposed on the food production process. However, it is unavoidable and if done correctly, can help ensure superior quality of the end product. It is possible to keep lubrication operations (such as oil changes and topping) to a minimum in the production environment by using maintenance-free or low- maintenance designs such as sealed bearings.
In systems using consumption lubrication (where the lubricant is used and needs to be replenished) such as bearings equipped with grease nipples and crimpers in can-closing machines, there is a risk of food contamination. The more regularly the product is replenished, the higher the risk of spillage.
In applications where the lubricant circulates - such as gearboxes, pumps and compressors - leaks can occur over time due to worn seals or pipe joints. One example is a vertically mounted gear in an agitator drive unit, where oil can leak through the seals into the process environment.
Mineral vs. Synthetic
Food manufacturers can choose from a range of mineral and synthetic oils and greases, but quality differences between them are significant.
General industrial fluids and greases (non H1) historically have been used in food and beverage manufacturing in the United States, but the potential for contact with consumable products makes them less-than-ideal for these applications.
Common food-grade mineral oil-based products have helped companies meet the USDA and NSF H1 food-grade requirement, but they often fall short of the lubrication performance requirements of modern food processing equipment.
The mineral-based lubricants usually are less expensive than synthetic lubricants and these “white oils” may not perform adequately under extreme conditions of load and temperature. Synthetic lubricants can be specifically designed for high performance, whether for the extreme low temperatures of freezers or for the high temperatures of ovens.
The increased oxidation and thermal stability of a synthetic lubricant, compared to a mineral or white oil-based product, make them more effective. Synthetic lubricants and their filters also need to be changed less often, reducing the potential for spills and the disruption of production lines. Synthetics also respond better to performance additives, which is important because of FDA restrictions on the type and concentration of additives allowed in food-grade oils.