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The Basics of Food-grade Lubricants
The food processing industry presents unique challenges to lubricant formulation engineers, lubricant marketers, plant lubrication engineers and equipment designers. While it is never desirable for lubricants to be allowed to contaminate raw materials, work-in-progress or finished product, the consequences of a lubricant-contaminated product are rarely more acute than in the food processing industry. As such, lubricants used in this industry have requirements, protocols and performance expectations that go well beyond typical industrial lubricants. This article will identify the basic differences between H1, H2 and H3 lubricants, their requirements and formulations, as well as proper lubricant selection, which is critical to food safety and machine reliability.
Food-Grade Categories and Definitions
Food-grade lubricants are lubricants acceptable for use in meat, poultry and other food processing equipment, applications and plants. The lubricant types in food-grade applications are broken into categories based on the likelihood they will contact food. The USDA created the original food-grade designations H1, H2 and H3, which is the current terminology used. The approval and registration of a new lubricant into one of these categories depends on the ingredients used in the formulation. The three designations are described as follows:3
H1 lubricants are food-grade lubricants used in food processing environments where there is some possibility of incidental food contact. Lubricant formulations may only be composed of one or more approved basestocks, additives and thickeners (if grease) listed in 21 CFR 178.3750.
H2 lubricants are lubricants used on equipment and machine parts in locations where there is no possibility that the lubricant or lubricated surface contacts food. Because there is not the risk of contacting food, H2 lubricants do not have a defined list of acceptable ingredients. They cannot, however, contain intentionally heavy metals such as antimony, arsenic, cadmium, lead, mercury or selenium. Also, the ingredients must not include substances that are carcinogens, mutagens, teratogens or mineral acids.4
H3 lubricants, also known as soluble or edible oil, are used to clean and prevent rust on hooks, trolleys and similar equipment.
As previously mentioned, the USDA approvals are based on the various FDA Codes in Title 21 that dictate approval for ingredients used in lubricants that may have incidental contact with food. These are mentioned in the following sections.
1.CFR 178.3570 – Allowed ingredients for the manufacture of H1 lubricants
21.CFR 178.3620 – White mineral oil as a component of non-food articles intended for use in contact with food
21.CFR 172.878 – USP mineral oil for direct contact with food
21 CFR 172.882 – Synthetic isoparaffinic hydrocarbons
21.CFR 182 – Substances generally recognized as safe
Some information from these standards is highlighted below.
Acceptable Food-Grade Basestocks
Depending on whether a food-grade lubricant is H1 or H2, the list of approved basestocks will vary. H2 lubricant basestock guidelines are less restrictive and, consequently, allow a broader variety of basestocks.
Many products used in industrial (non-food) plants are also used in food plants for H2 applications. H1 lubricants are much more limited since they are designed to allow for accidental exposure with the processed foods. H1-approved lubricant basestocks can be either mineral or synthetic:
Petroleum-based lubricants – Mineral oils used in H1 food-grade lubricants are either technical white mineral or USP-type white mineral oils. They are highly refined and are colorless, tasteless, odorless and non-staining. Technical white oils meet the regulations specified in 21 CFR 178.3620. USP mineral oils are the most highly refined of all white mineral oils.6
Synthetic lubricants – Synthetic H1 lubricant basestocks are often polyalphaolefins (PAO). Compared to white mineral oils, they have significantly greater oxidation stability and greater range of operating temperatures. Another approved H1 synthetic basestock is polyalkylene glycols (PAG). These lubricants are more increasingly used in high-temperature applications.
Dimethylpolysiloxane (silicones) with a viscosity greater than 300 centistokes (cSt)7 is also permitted for H1 lubricants. Silicones have even higher thermal and oxidation stability than PAO and PAG base oils.
Acceptable Food-Grade Additives and Thickeners
Often, basestocks are not able to meet the severe demands required in food processing work environments. To improve the performance characteristics of base oils, additives are blended into the formulation. The types of antioxidants, corrosion inhibitors, anti-wear, extreme pressure additives and concentration are limited by 21 CFR 178.3570.
Greases are lubricating oils that have a thickening agent added to the formulation. Among approved grease thickeners are aluminum stearate, aluminum complex, organo clay and polyurea. Aluminum complex is the most common H1 grease thickener. They can withstand high temperatures and are water resistant, which are important properties for food processing applications. Prior to 2003, greases with calcium sulfonate thickeners were not designated as H1 by the USDA or FDA but have since been approved. 8
Selecting Which Machines Require Food-Grade Lubricants
Selecting whether to use an H1 or H2 lubricant can be challenging. A lubricant used on a conveyor system running over a food line must be an H1 category oil; however, a conveyor system running underneath a food line may not necessarily be safe to use an H2 oil.
According to the Hazard Analysis and Critical Control Point (HACCP) program implemented by the USDA, each lubrication point has to be evaluated for where contamination might occur. Most major food-producing companies have begun using the HACCP system, but their plans don’t always recognize the importance of a lubrication survey. A number of lubricant suppliers offer to assist with the lubrication survey portion.
Because H1 lubricants are limited by types of additives and in the past only used mineral oil basestocks, H1 lubricants in certain instances provided less protection and shorter lubricant life. Now that synthetics are used, some H1 lubricant performance can exceed non-food-grade lubricants. This is significant in allowing consolidation and avoiding accidental cross-contamination of H1 and H2 oils and contamination of H2 oils with food.
Other Issues Surrounding Food-Grade Lubricants
Using H1 food-grade lubricants is no replacement to sound design and maintenance. H1 lubricants are still only approved for minimal, incidental contact. If a plant uses food-grade lubricants, the FDA limits lubrication contamination to 10 parts per million – that’s 0.001 percent.
Also, the lubricant certification process does not include lubricant plant audits and sample testing to ensure formulation; it is strictly comparing the formulation to the approved list. Richard Pinchin, formerly with Shell International and a supporter of a more rigorous certification process, indicated at an NLGI meeting: “I know of five instances in the last three years where food-grade claims are not justified.”1
Understanding the differences between H1, H2 and H3 lubricants and making the proper lubricant selection is critical to food safety and machine reliability. As an additional source, NSF’s Web site provides lubricant requirements for food-grade products and gives a free access listing of certified food-grade lubricants at www.nsf.org/usda/psnclistings.asp.
Machinery Lubrication (1/2009)