Retort-processed cat food is food that has been sealed inside a special pouch and then subjected to sterilisation at gentle temperatures. The retort process is a form of commercial sterilisation borrowed from the human food industry and is designed to destroy bacteria, pathogens, and spoilage organisms so the sealed product can be stored at room temperature for months or years without refrigeration. Retorting eliminates the need for adding harsh chemicals and preservatives to cat food to keep it shelf stable. The steam-cooking inside the retort machine cooks the food inside the sealed packs, thus removing all microbes. The outside air cannot enter the pouch, therefore no outside microbes can touch the food. This keeps the food shelf-stable for a long time. Of course, once the seal is broken, it’s just like any other food; it must be put in the fridge and served within 48 hours for maximum safety.
Why does this matter?
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Processing cat food heavily causes substantial degradation of heat-sensitive vitamins, particularly vitamin B1 (thiamine), vitamin C, and folate. Thiamine deficiency in cats causes neurological symptoms including loss of coordination, seizures, and in severe cases, death. Therefore, retort packaged cat food is actually a good alternative because of its high nutrient retention.
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The Maillard reaction, which occurs during any high-heat food processing, reduces the bioavailability of essential amino acids, particularly lysine and cysteine. For cats, whose amino acid requirements are uniquely demanding (they need dietary taurine, arginine, and methionine that cannot be substituted by plant sources), this loss of amino acid bioavailability has real biological consequences over time. Retort processing the cat food actually lowers the toxic burden that comes from the Maillard reaction, such as the Advanced Glycation End Products (AGEs).
What do vets generally agree on?
Veterinary nutritionists broadly agree that retort-processed cat food is significantly better than ultra-processed cat food, both in terms of moisture content and protein bioavailability. Such fresh cat food retains more nutrients, has fewer AGEs, and provides greater digestibility. Retort processing is a practical technology that makes pet food shelf-stable without adding any preservatives. This is why it is used to pack BLEP cat food, so that we can keep our recipes 100% natural, preservative-free and maintain a 12-month shelf stable!
When to be careful?
Not all retort-processed cat food has high nutritional value. Some may still contain sub-par ingredients like meat by-products and derivatives, which have little bioavailability. In such cases, no matter how much nutritional value is saved by retorting, the overall impact will remain low because of ingredient quality.
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