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Pet Food Processing Methods:

“Processing” refers the steps taken by the manufacturer to produce food that is nutritional and safe for your pets.  While all methods address food safety, there are trade-offs that need to be evaluated when making food choices.  Sterilized food may sound safer but may actually be less healthy for your pets health if the good bacteria have been destroyed along with the bad.   A healthy microbiome needs to have plenty of ‘good’ bacteria to function properly, and these help to prevent growth of any ‘bad’ bacteria. (See article about tradeoffs)

USDA and FDA have established ‘safe’ levels of bacteria for all foods intended for human consumption. The USDA allows acceptable levels of bacteria in raw meat for human consumption. While, FDA currently has a “zero tolerance” policy for pet food which means that no bacteria, whether good or bad, can be present.  No one disputes that fresh whole food is healthier than highly processed food, but fresh pet food manufacturers are challenged with how to satisfy FDA’s zero tolerance policy while still preserving the natural benefits of fresh whole food sourced and passed from the USDA.

Sourcing:

The quality of any product begins the ingredients – how they are sourced directly impacts how they will be processed into pet food.   Even the highest quality ingredients can be processed to death, but no process will convert low quality ingredients into high quality nutrition.  

Raw meat and fresh whole food naturally contain bacteria at levels the USDA has determined to be safe for humans.  But the same products that are safe to buy at the grocery store may not meet the FDA’s zero tolerance policy for pet food.  This poses a challenge for fresh pet food manufacturers who source human-quality ingredients and want to preserve the natural nutrients in the fresh food but are required to add extra processing in order to meet the FDA’s pet food guidelines – which are more strict than human food!

Processing Methods:

Depending on the type of product being made (fresh/raw, kibble, etc.) manufacturers may use one or more of the following methods for ensuring the safety of their products:

Low Heat or “Gentle” Cooking: Ingredients are subjected to low heat to destroy pathogens without destroying other heat-sensitive nutrients.  Cooking methods include baking, sous-vide, or dehydrating.

  • Pros: Heating to minimum recommended temperatures is effective at eliminating all pathogens.
  • Cons: Heat damages microflora and heat-sensitive nutrients.  The extent of the damage depends on the temperature to which the food is cooked, the higher the heat the more nutrients are destroyed.

Dehydration: Food is dried using heat.

  • Pros: Heating to minimum recommended temperatures and removing the moisture eliminates pathogens.
  • Cons: Heat damages microflora and heat-sensitive nutrients.  The extent of the damage depends on the temperature to which the food is cooked, the higher the heat the more nutrients are destroyed. Moisture must be added back into the product before being fed to the pet.

Freeze-Drying: Frozen food is dehydrated (dried) at low temperature.

  • Pros: Effective at eliminating pathogens.
  • Cons: The extent of any damage to microflora and heat-sensitive nutrients depends on the level of heat used in the process.   

Extrusion: Dry powders (from rendering) are mixed with minimal moisture and formed into dry pellets using high heat and pressure.  After extrusion the pellets are sprayed with oils containing preservatives and heat-sensitive nutrients.

  • Pros: Effective at eliminating pathogens during extrusion.
  • Cons: Pathogens may be present in the final spray.  Longer shelf life without refrigeration may allow time for new pathogens to grow.

Canning: Ingredients are added to airtight cans or packages and heated at high temperatures and pressures. 

  • Pros: Effective at eliminating pathogens.
  • Cons: Destroys microflora and heat-sensitive nutrients.

Fermentation: Beneficial bacteria, like lactobacillus, or salt, are added to food to convert carbohydrates into acids or alcohols which help preserve the food.

  • Pros: Eliminates some pathogens, provides for an abundance of “good” bacteria to compete against the “bad” bacteria – called competitive inhibition. Does not harm heat-sensitive nutrients.
  • Cons: Not all pathogens are eliminated. 

High-Pressure Processing (HPP): Subjects the product to very high pressure without added heat to destroy pathogens.

  • Pros: Effective at reducing pathogens.
  • Cons: Damages microflora and pressure-sensitive nutrients.

Rendering: Animal waste products (such as fat, bone, and offal) are heated until the fat and protein separate. The fat is converted into the animal fats used in pet foot and the protein is used to produce meat meals.

  • Pros: Effective at eliminating pathogens.
  • Cons: Lower quality waste products have lower nutritional value and may contain waste from pathogens (endotoxins) present in the ingredient prior to rendering.  All microflora and heat-sensitive nutrients are destroyed.

Surface Rinse (peroxyacetic acid (PAA), Lactic Acid, Ozone): Ingredients are rinsed with substances that remove or destroy pathogens. 

  • Pros: Targets pathogen-prone ingredients with minimal nutrient damage. The rinses often breakdown into water after contact with the food leaving minimal residue.
  • Cons: May not eliminate all bacteria.

Bacteriophage: Specific virus that targets and destroys specific bacteria.

  • Pros: Kills specific pathogens without harming good bacteria or nutrients.
  • Cons: May not eliminate all bacteria.

Bio-preservation: Specific microbes are added to crowd out and destroy the harmful ones. 

  • Pros: Adds beneficial microbes without affecting nutrients.
  • Cons: May not eliminate all pathogens.

Bottom line, there are many processing methods manufacturers can use to ensure food safety while ensuring that the pet receives adequate nutrition.  Fresh food manufacturers using minimal processing to preserve natural nutrients face the added challenge of using human-quality food ingredients that meet FDA zero-tolerance standards as well as those the USDA has established for human foods.