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Cute puppy eating his food at the parkKeeping pets happy and healthy is a no-brainer.

Pet parents scour the web and consult with veterinarians in order to find the best of the best to suit our pet’s discerning palettes (even pets can be picky eaters!). Picture this: You finally find a brand that meets the nutritional needs of your companion, it fits within budget, and your pet actually loves the food! Everything is going well until there is ANOTHER recall within the pet food market, and your pet food is part of the recall...

This situation is a pain for pet owners (just simply finding a new food can be a hassle), but it can also be dangerous - causing illness, injury, or death. This reflects poorly on the pet food manufacturers and can drastically affect sales as well as legal ramifications. How can manufacturers up their standards for production, improve safety and shelf-life, all without increasing costs that then get passed onto the customer? There isn’t one answer to this question, but testing peroxide value of pet foods and animal feeds can help ensure food safety across the board.

What is Peroxide Value?

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You may be more familiar with peroxide value being called rancidity. Rancidity or a poor peroxide value can strike during any step of the pet food production process (ingredients/materials, raw products, production, finished product/packaging). As fats, oils, proteins, etc., are exposed to the elements, they have small chemical reactions. These chemical reactions cause the oils and fats to oxidize. This affects the smell, taste, texture, and aesthetic of the finished products. Taking a whiff of pet food can be a bit stinky (hey, they have different tastes than us humans) – but does the food smell stale or a bit off? It’s possible that rancidity may have started to set in. The more the pet food gets processed, the higher the risk for rancidity. For example, if the food is subjected to elevated temperatures during processing, that increased temperature can accelerate the rate that the food oxidizes.

Why Test Peroxide Value?

Testing for peroxide value will elevate your quality assurance and production processes from where they are now. Not only will this test help you guarantee your product’s freshness, you can help guarantee safety and quality. One bad batch of pet food out in stores and in the customer’s hands could permanently taint their opinion of that company. Testing your product from start to finish not only aids you in your decision making throughout the manufacturing process, but it helps make a better product. Luckily, testing for peroxide value, or rancidity is not too difficult or costly.

How Do You Test For Peroxide Value (Rancidity)?

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A complete explanation can be found HERE but, we won't leave you hanging. Peroxide value when tested typically gives you results in the amount of oxidation per kilogram of the fat/oil you are testing. Generally speaking, materials that have a value of 10 meq or below are considered fresh and good for usage. Anything that hits 30 meq and above, the product is generally considered rancid. In addition to testing peroxide value for rancidity, there are a few other tests that you can consider to get a full picture of your products. From our Peroxide Value Blog:

  • Free Fatty Acids (FFAs) - Used to determine hydrolytic rancidity (as opposed to oxidation). Free fatty acids can be the by-product of microbial activity.
  • p-Anididine (p-AV) - A measure of aldehyde values in fats and oils; particularly unsaturated fats.
  • TBA Rancidity (TBAR) - A measure of aldehydes created from the oxidation of fats.
  • Oxidative Stability Index (OSI) - Determines the relative resistance of fats or oils to oxidation.

Ways To Test

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You can test peroxide value through either a photometric or titration method. For testing solid foods or ingredients, we highly recommend titration as you will avoid common interferences that come with a photometric method. Titration is one of the most precise ways to monitor peroxide value in ingredients, materials, and products. While you will work with chemicals for the titration, an automatic titrator will help you to have great accuracy and repeatability – virtually taking the guesswork out of testing.
 

What Is Needed To Run A PV (Peroxide Value) Titration?

Due to the complex nature of the sample (pet food, animal feed etc.) you will need to perform particular sample preparation steps prior to titrating. The sample preparation follows a three-step extraction using hexane. It is VERY IMPORTANT that you follow all safety protocols when handling the necessary chemicals (please reference the chemical MSDS or SDS for exact safety measures). The titration method used on the extracted residue from the sample is per AOCS Cd 8b-90. 

You will need:

  • An automatic titrator (highly recommended)
  • An ORP electrode
  • Saturated Potassium Iodide Solution
  • 0.01 M Sodium thiosulfate (this is your titrant)
  • PVDF stirrer propellers (this will stir your sample, and it is important to get a propeller with this particular plastic. The chemicals used to break down your sample to be tested can react and melt certain plastics. PVDF is compatible with the chemicals needed for this titration and will perform well throughout multiple titrations.)
  • Glacial acetic acid
  • Chloroform or Iso-octane
  • Hexane
  • Class A Volumetric Glassware
  • Automatic pipette (5 mL)
  • 150 mL glass beakers
  • A grinder or blender
  • Rotary Evaporator
  • A chemical hood (this can be a small lab-top hood, or a larger fume hood that is attached to the wall. If you do not have access to a fume hood, please make sure that the space you are working in is well ventilated and/or that you have a respirator mask on hand. The chemicals you will be working with produce fumes and should not be respirated.)
  • Deionized Water
  • Latex Gloves
  • Safety Goggles
  • Lab Coat – not only will you look snazzy, but you will be better protected.

While these materials may seem like a lot, moving to test in-house may save you time and money in the long run.  Sending samples out for testing can take weeks to get back. Testing in-house helps to guarantee product safety as you can test in real-time as they are produced.

Have questions?

Contact a Hanna Technical Specialist at sales@hannainst.com, the chat in the lower right-hand corner of the screen, or contact your local Hanna office.

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