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Complete Guide to the Selection of Food Grade Stainless Steel for the Food Processing Industry

Last Updated: July 2, 2019
Posted by: Shelly Stazzone in Safety

Food processors the world over are facing stricter and stricter restrictions in the form of international regulations and compliance. This is a fact that contributes to the betterment of a healthy globe, but it also comes with a tight learning curve for processors.

You see, as technology evolves and more and more facilities are making use of autonomous components for faster production times, these new pieces of equipment must be tested and confirmed as being ‘food-grade’ first, and only contain materials and finishes that have been deemed safe for use in the food industry. This means that materials, such as food-grade stainless steel, will also be put to the test during audit-time –and if they don’t fit the bill to the letter, it could mean very bad news for the producer. Stainless steel food processing equipment

So, if you work in food production or are part of a team that designs equipment for the industry, it’s high time that you educate yourself on the potential compliance headaches that can come with surface materials. Today, we’re going to delve deep into food-grade stainless steel and the form that it must exist in when used in processing facilities.

In this guide, we’ll discuss:

Why Stainless Steel is a Good Choice for Processors

When it comes to equipment surfaces used in food processing, it’s safe to say that stainless steel is the gold standard for a multitude of reasons. For one, it comes in a wide variety of finishes that serve as strong, versatile options for the most cutting-edge food processing equipment used in today’s facilities.

Here are some more reasons why food-grade stainless steel is so often used by food processors:

  • Its impermeable surface prevents contamination
  • It’s available in a wide range of versatile finishes
  • Its smooth surface is designed with easy cleaning in mind
  • In its highest quality form, it does not nick, dent, or break easily
  • It isn’t susceptible to acid erosion that is sometimes created by certain foods
  • Its surface provides chemical and bacteriological neutrality
  • It’s made to blend easily with other finishes
  • It’s made to handle frequent washings with noxious detergents
  • Its finish is fire-resistant
  • It acts as a neutral surface for food products, which means it doesn’t pick up or transfer any food smells
  • When maintained sufficiently, it doesn’t fall victim to corrosion or aging
  • It has stain and transfer-resistant properties

 

Commercial Kitchen Stainless Steel

Of course, stainless steel won’t be found in each and every component of a food facility, but it does represent most standard finishes. Here are some of its most common applications via Alliant Metals:

  • Evaporator tubes
  • Flour silos
  • Syrup tanks
  • Beer kegs
  • Ice cream molds
  • Conveyor systems
  • Double wall food transport container
  • Tanks holding dairy
  • Food mixers
  • Peeling machines
  • Food pulverizers
  • Confectionary equipment
  • Industrial ovens

In addition to the stainless steel used for food-contact surfaces and other materials, food processing equipment is also equipped with equipment nameplates, which convey essential information such as the product name, health and safety warnings, and important equipment data. Stainless steel equipment nameplates are the preferred choice in the food processing industry, thanks to stainless steel’s antibacterial properties, excellent resistance to dents, scratches, and stains, and superior performance in highly caustic or acidic environments.

Depending on the specifications of the facility and product, stainless steel finishes can also be used for a myriad of other tools and equipment. As you can see by the above applications, its versatile, ultra-smooth surface is appropriate for all kinds of materials and temperatures, whether the food is hot or cold, or in liquid or solid forms.

What Makes a Stainless Steel Food-Grade?

Because there are roughly 150 grades of stainless steel on the market today, it can be very easy to make the mistake of selecting a finish that doesn’t meet all FDA requirements. Having said that, many of the finishes may look similar, but in reality, they are very different when it comes to what they can handle on a day-to-day basis.

Generally speaking, food-grade stainless steels boast surfaces that are much less permeable – and much smoother – than the others. For example, these special forms of stainless steel must be able to withstand acids, alkalis, and chlorides, such as salt, which is frequently introduced to a steel’s surface during processing. If the stainless steel doesn’t have this property, then these caustic materials could contribute to premature corrosion – and, once corrosion starts to form, the unit must be taken out of circulation immediately because of its uneven surface.

For industrial food applications, where this damaging corrosion is more prevalent, producers may make the choice to put the stainless steel through an electropolishing treatment. This one-time treatment enhances the acid-resistance properties, which could, ultimately, prevent corrosion that might lead to contamination.

Food-Safe Stainless Steel Properties to Look for

Now that you know what types of stainless steel finishes make for food-safe and/or food-grade applications, let’s take a look at the properties that every producer needs to be aware of before introducing a component into its facility: Stainless steel heat resistance

  • It is comprised of the right amount of chromium: In order to be considered stainless, the steel must have a chromium content of at least 11-percent. This factor is the one that makes it resistant to rust and corrosion. Looking at it in scientific terms, it is the chromium that gives the outer-layer of steel its ability to be oxygen-bound; this forms a passivation layer that makes it difficult for rust to form.
  • It has a high resistance to heat: As mentioned, one of the reasons why stainless steel is so fitting for a variety of different food processing applications is the fact that it is highly resistant to heat. As a matter of fact, its finish also contains fireproof properties. If its nickel and chromium content (we’ll get more into this later) aren’t at the right levels, then the stainless steel might not be able to withstand the heat needed for industrial food applications.
  • It can tolerate moisture and certain chemicals: Virtually all kinds of stainless steels are made to tolerate high levels of moisture and the application of certain chemicals, so it’s no surprise that the food-grade ones can handle these challenges with no fear of pitting, cracking, or corrosion.

The Best Food-Grade Stainless Steels for the Processing Industry

As stated above, there are roughly 150 different types of stainless steels available for use today, but there are only a few that are sturdy enough to be considered “food-grade.”

Though there are certain exceptions to the rule, almost all of the food-grade stainless steel is manufactured from 300 and 400-series steel. Here’s why these series are the most suitable for food production applications:

  • 300-series: This series is fabricated with both chromium and nickel, with about 18% and 8% by mass, respectively. With this specific formulation, the steel’s finish is non-magnetic.
  • 400-series: This series contains mostly chromium paired with a small number of other assortments of other elements. Because of its special composition, the finish will always attract a magnet.

Note: The latter descriptions of both the 300- and 400-series stainless steels are important to pay attention to, as not every stainless steel component should have magnetic–or non-magnetic– properties in its application. If you have plans of purchasing a piece of stainless steel equipment, first ensure that its magnetic properties will fit well and/or not disrupt surrounding equipment or components.

Dairy processing

Let’s take an even closer look at the options that are available for processors within the 300 and 400 stainless steel series:

  • 304: This is the most commonly-used food-grade stainless steel option on the market today. It is most often used to process dairy, beer, and miscellaneous sanitation practices within a facility.
  • 316: Yet another popular food-grade stainless steel. It’s a variety that is used more often in commercial food production as it has better corrosion resistance than 304. This is because it contains more of the element nickel than its counterpart.
  • 430: This form of stainless steel contains less nickel than those seen in the 300-series, which means it’s more susceptible to corrosion in harsh environments than those that are part of the 400-series. Generally speaking, 430 must be dried soon after it encounters moisture in order to prevent rusting.

Another thing to note is that it’s common to see another set of numbers beside the grade, for instance, “18/8”; this is meant to stand for the stainless steel’s chromium and nickel contents.

If you are looking for a super-sturdy commercial food-grade stainless steel, then the higher these numbers, the better. As you know, nickel prevents rusting, but it is not always included in high levels as only certain amounts of it can be consumed per day safely, especially if the person who is consuming the food has an allergy to the element. These levels are yet another aspect to consider when selecting the stainless steel that will most safely integrate into your food production facility.

What the Food Processing Industry Needs to Know About Stainless Steel

Once the appropriate stainless steel is selected, it’s time that you take pains to gain a working knowledge of your facility’s food-grade surfaces, whatever form they may be in.

Cleaning Your Food-Grade Stainless Steel Parts

From the moment your facility integrates its new stainless steel components, it’s key that you establish a clear, concise cleaning and maintenance plan. Of course, if you are working in commercial food production, then you will already be cleaning the stainless steel regularly in order to adhere to regulations, but the routine cleansing should not stop there. Commercial kitchen

Depending on the variety of food-grade stainless steel selected and the food that is encountering the finish, you will choose from this list of appropriate cleaning methods:

  • Steam cleaning with water only
  • Mechanical scrubbing with customized machine
  • Detergents and/or scouring powders
  • Alkaline solutions for rust-prone finishes
  • Organic solvents
  • Nitric acid

Before forming your cleaning plan, be sure that you get advice from your vendor on what works best on your finish – and also be sure that you double-check regulations in order to see what cleaning agents can be used in your processing facility.

Safeguard Your Food-Grade Stainless Steel Against Corrosion

If you have taken the care to select a stainless steel that can withstand the environment of your production line, then you shouldn’t have to fear corrosion too much. But, if you don’t maintain its finish, then you could end up causing some degradation yourself.

One of the most common mistakes that those who are new to working with food-grade stainless steel make is that they clean its finish with a plain steel brush. Although you might use this on similar metal surfaces at home, it should never be used on stainless steel, especially chromium-rich food-grade stainless steel, as the coarseness of the bristles can easily break up the bonding oxide layer. This can lead to cracks, crevices, and rust that can give you compliance issues in the future.

In addition to caring for your stainless steel components, make sure that you follow any and all advice given to you by your vendor. And, because stainless steel, even the food-grade variety, can have pits and corrosion that may not be noticeable with the naked eye, it’s important that you use all of the necessary detection devices in order to ensure that your facility is in line with all binding laws and regulations.

Further Reading on Food-Grade Stainless Steel Options for the Processing Industry

For more information on the specifics surrounding food-grade stainless steel options and what they mean for your food equipment business, visit the following resources:

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