Stainless steel plays a crucial part in the production and safety of our food.  In the food processing industry, stainless steel is used throughout the entire process from harvesting, handling, and storing, to cooking and serving.  Over 200,000 tons of stainless steel is used each year by the food processing industry in N. America alone.

What is stainless steel?

Stainless steel is a combination of metals, also known as an alloy.  Resistant to rust and tarnishing, stainless steel is made of some of the most basic elements found on Earth: iron ore, chromium, silicon, carbon, nitrogen, and manganese. 

To be recognized as stainless steel, the composition must have a minimum of 10.5% chromium content by mass and a maximum of 1.2% carbon by mass.  Chromium is the element that gives stainless steel its famous corrosion resistance.  Contrary to its name, stainless steel is not truly stainless; the chromium helps it to withstand abuse for much longer before showing signs of wear compared to standard steel without chromium. 

There are over 50 types of stainless steel recognized as standard alloys, in addition to many proprietary alloys produced by different stainless steel manufacturers.  These different types are distinguished by their unique composition. 

Why is stainless steel used in the food industry?

For many sanitary food handling applications, stainless steel is a popular material choice.  Not only can food-grade stainless steel stand up to harsh temperatures, the material’s protective oxide layer helps prevent the formation of rust that could contaminate foods.  Perhaps the most important reason is that food-grade stainless steel contains no chemicals that can migrate into foods.

Additional benefits of using stainless steel in the food industry include:

• Non-reactive surface: Stainless steel is a non-reactive metal, which means that you can use it to cook foods that are acidic, such as citrus, tomatoes, and vinegar.  Other metals, like aluminum and iron, are reactive. Cooking acidic foods in these metals may affect the flavor of the food, typically adding a metallic flavor, and can damage the surface of the metal.
• Corrosion resistance: Stainless steel is especially resistant to corrosion and rusting compared to other metals, which makes it perfect for use in the kitchen.  Food-grade stainless steel is often used for kitchen equipment, which can be costly to install.  But, because most grades of stainless steel are highly corrosion-resistant, the equipment does not need to be replaced as frequently.
• Strength: Food-grade stainless steel is extremely strong, making it an excellent material to use in heavy-duty equipment or in shelving for storage areas.
• Ease of cleaning: Other materials, such as wood or plastic, have grooves or openings where bacteria can invade and grow.  Stainless steel is smooth and doesn’t provide a place for bacteria to hide, allowing it to be easily cleaned. 
• Cost: When properly cared for and maintained, stainless steel has low maintenance costs.

The Most Common Types of Stainless Steel

Just because stainless steel is labeled “food safe” does not mean that it is the right material for your facility or production process.  There are many different types of food-grade stainless steel, each containing different compositions and properties.  The most common types is 304. 

304 Stainless Steel

Also known as “18-8” stainless steel, because it contains 18% chromium and 8% nickel, 304 is the most common stainless steel used around the world.  It accounts for more than 50% of all stainless steel produced.  304 is an economical and practical choice for most environments. 

304 can withstand corrosion from most oxidizing acids.  This durability makes it easy to sanitize, and therefore ideal for many kitchen and food applications.  It also has good forming and welding properties, allowing it to be manufactured into a variety of shapes. 

Common uses for 304 stainless steel include brewing, milk processing, and wine making.  It is also found in most refrigerators, stoves, sinks, dishwashers, fermentation vats, and storage tanks and can withstand corrosion caused by various chemicals found in fruits, meats, and milk.  One of 304’s biggest weaknesses is its susceptibility to corrosion from chloride solutions, or from saline environments such as saltwater.