Stainless Steel for Food Processing: 304 grade vs 316 grade stainless
Stainless steel is a popular material for food processing because of its heat resistance and smooth finish. It can withstand high temperatures that are often used during the processing of foods, and it also has a protective, chromium-enriched oxide layer that protects against rusting. Chromium content is what makes steel considered stainless.
Food-grade stainless steel must be smooth. The surface cannot have any cuts, cracks, or other blemishes. If there are blemishes, food particles may get stuck in the cracks, even after being cleaned. This could result in the growth of potentially harmful bacteria.
What Grades of Stainless Steel Should Be Used for Food Processing?
The most commonly used stainless steel for food processing is 304 grade stainless steel. This grade can be found in most kitchen equipment because of its resistance to corrosion. The chromium content will prevent the equipment from rusting.
However, from an industrial standpoint, 304 stainless will eventually corrode when used in contact with salt, salt water, and/or highly acidic foods for a prolonged period of time. To avoid saltwater corrosion, or corrosion from highly acidic foods, 316 grade stainless is the superior choice.
Its advanced resistance to corrosion makes 316 grade stainless the second most common material used for food processing. While 304 stainless is resistant to corrosion, 316 stainless is more resistant. This is due to the addition of molybdenum to the alloy. Molybdenum is a chemical element that, when added to stainless steel, improves resistance to corrosion. Although the chromium content in steel already provides corrosive resistance, the addition of molybdenum offers stronger protection against pitting and crevice corrosion.
Which is better?
Deciding which is better solely depends on the application. For most food processing scenarios, 304 stainless will work just fine. When working with salt water or highly acidic foods, 316 is the superior choice. Why not just always use 316 stainless? The addition of molybdenum drives up the price of the material, making it more expensive than 304.
For a kitchen knife used for dicing tomatoes, 304 stainless is more than adequate, but for processing tens of thousands of diced tomatoes, 316 stainless is the better option because of the prolonged exposure to the acidic tomatoes. In that case, the extra cost of 316 stainless is worth it. If the goal is to process thousands of tomatoes, than 316 stainless will last longer than 304.
At Switzer, we work with both grades. Are you developing food processing equipment? Our team of experienced engineers can assist with your next project. Contact us to learn more!Read More →