Food Grade Lubricants

Health and safety are priorities for food, drink and drug manufacturers. Standards of cleanliness and hygiene are as important on the shop room floor as in hospital operating rooms. But when it comes to production equipment, lubrication keeps the business of feeding and healing the nation on track.

Lubricant leakages and maintenance are an inevitable part of all industries. Lubricants do not discriminate against the materials with which they come into contact. So, the food-processing and pharmaceutical industries have additional challenges in selecting the right lubricants to do the job. This article looks at the previous, current and future standards relating to lubrication in this industry.

What is a Food-Grade Lubricant?

Food-grade lubricants must perform the same technical functions as any other lubricant: provide protection against wear, friction, corrosion and oxidation, dissipate heat and transfer power, be compatible with rubber and other sealing materials, as well as provide a sealing effect in some cases.

In addition, different applications within the food and drugs business demand that lubricants resist degradation from food products, chemicals and water/steam, must exhibit a neutral behavior toward plastics and elastomers, and have the ability to dissolve sugars. These oils must also comply with food/health and safety regulations, as well as be physiologically inert, tasteless, odorless and internationally approved.

Lubricants can be subjected to intense environmental contaminants. A corn-milling environment generates significant dust. Although not as hard as silica-based dust, it still presents a problem for filtration. A meat plant requires stringent steam cleaning at all times, so the risk of water contamination is high. Some plants experience as much as 15 percent by volume of water in their gear oils.

Another aspect of lubrication contamination that poses a risk to food-grade lubricants is the growth of microorganisms such as bacteria, yeast and fungi. While these can be a risk in industrial environments, the opportunity for contamination in the food-production environment is even greater.

Food-Grade Categories:

The United States Department of Agriculture (USDA) created the original food-grade designations H1, H2 and H3. The approval of a new lubricant and its registration in one of these categories depends on the list of the ingredients.

H1 lubricants are food-grade lubricants used in food-processing environments where there is the possibility of incidental food contact.

H2 lubricants are food-grade lubricants used on equipment and machine parts in locations where there is no possibility of contact.

H3 lubricants are food-grade lubricants, typically edible oils, used to prevent rust on hooks, trolleys and similar equipment.

Deciding whether there is a possibility of contact is tough, and many have erred on the side of safety with respect to selecting H1 over H2.

Formulation of food grade lubricants:

Composition of food grade (H1, H3) lubricants is defined by CFR 21, Section 178.3570.5 Formulations are developed to meet technical requirements including OEM specifications for machinery. Open, closed, and worm gear oils, hydraulic fluids, chain lubricants, cylinder oils, and can seamer oils are examples of specialised products. Lubricant formulations may also be required to meet applicable laws and regulations pertaining to occupational, health, safety, and environmental considerations.

In non-technical terms, lubricants are mixtures of oil and low levels of additives which enhance performance. Lubricants consist primarily of base oils. Three types of base oils are used to formulate food grade lubricants:

• Very pure grades of “white” mineral oils are highly refined from naturally-occurring deposits of petroleum.
• Synthetic base oils such as PAOs (polyalphaolephins), PAGs (polyalkalene glycols), and silicones are manufactured.
• Vegetable oils including castor, palm, soybean, canola (rapeseed) and sunflower oils are harvested from crops.

Base oils have limited capabilities as lubricants. It is necessary to modify them with chemical additives in order to improve their performance. Additives comprise a small percentage of most formulations but make critical contributions. They are chosen on the basis of performance requirements, solubility in the specific base oil, and possible interactions between additives.

The main types of additives used in food grade lubricants are:

• Friction modifiers, anti-wear additives, extreme pressure additives
• Antioxidants
• Corrosion and rust inhibitors
• Viscosity modifiers and pour point depressants
• Surfactant detergents, dispersants, and emulsifiers
• Antifoam agents and defoamers 

Approval and Compliance:

Approval and compliance was, in the past, the responsibility of the USDA. The agency is considered an internationally renowned authority on consumer safety issues with regard to the food-processing industry. Its efforts essentially covered federally inspected meat and poultry facilities, but were rapidly adopted by other sectors such as fisheries and retail food operations.

Biodegradable Lubricants:

Biodegradability is one of the properties of environmentally friendly lubricants. Interest in biodegradable lubricants continues to gain momentum for reasons as below:

Biodegradability refers to the tendency for a lubricant to be chemically decomposed by naturally-occurring bacteria in soil and water. That is, bacteria consume hydrocarbons present in base oils (and some additives). A series of chemical reactions is required to completely transform the hydrocarbons into CO2, water, and trace minerals. Biodegradation causes lubricant to dissipate after release into the environment. Biodegradability can be measured in field tests. The level of contamination in soil is monitored after a controlled release of lubricant.

In practice, standard laboratory tests are more often used to evaluate biodegradability. These tests measure rates of chemical conversion of lubricants by bacteria. They are frequently carried out in the presence of air (“aerobic”) and water (“aqueous”), under well-controlled conditions:

Biodegradability, or lack thereof, is a major determinant of the environmental hazard presented by release of a lubricant. According to the National Research Council, the release of petroleum (and lubricants based on mineral oils) can be hazardous to the environment for several reasons.

Biodegradable lubricants contain vegetable oils and certain synthetic base oils, which can biodegrade and dissipate much more rapidly than mineral base oils. Biodegradable hydraulic fluids and other total loss lubricants were first devised in response to specific mandates for their use. Even more recently, biodegradable multipurpose grease, rail curve grease, wheel flange lubricant, and open gear lubricant have been developed.

Formulation Guidelines:

With respect to formulation requirements, the draft standard states the product shall not contain intentionally added heavy metals, and shall not contain ingredients classified as carcinogens, mutagens or teratogens. A carcinogen is a substance that when ingested, may cause cancer. A mutagen is a substance which causes mutation. A teratogen is an agent which raises the incidence of congenital malformations.

For certain types of lubricants, these shall be neutral in taste and odor, and in addition, should be selected according to the use such that the lubricant withstands temporal, chemical, biological, thermal or mechanical stresses without premature degradation or impact to its neutral state.

The evaluation criteria cover three main aspects: food-grade lubricants, evaluation requirements and ingredients. Evaluation requires that the manufacturer or supplier disclose the product name, a qualitative/quantitative identification of all constituents, the Chemical Abstract Service (CAS) number where applicable, the chemical ingredient names based on the International Union of Pure and Applied Chemistry (IUPAC) rules, suppliers or sources of each ingredient, any prior product approval from a state or country regulatory authority, and any appropriate FDA regulatory reference for each ingredient.

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