Extruded or Cold-Pressed Pellets? The Facts on Parrot Diets
Have you ever been shopping around for parrot food, only to see an advertisement for “cold-pressed pellets?” Or maybe, while reading the fine print on another food brand, you read the phrase “extruded diet.”
Many parrot owners have at least stumbled across these phrases, both of which describe how a formulated diet has been made. You’ve likely heard the argument that cold-pressed pellets are more nutritious than extruded diets because they’re made at lower temperatures, keeping more nutrients intact. The topic can seem divisive and confusing to someone who just wants to give their flock the best food possible.
Worry not! In this article, we’ll give you a better idea of what “cold-pressed” and “extruded” mean, and talk about how these preparation methods can (and can’t) impact nutrition.
What do the phrases “cold-pressed” and “extruded” actually mean?
You can usually tell cold-pressed pellets apart from extruded diets based on appearance. Cold-pressed pellets are almost always cylindrical, as the ingredient mixture is compacted and forced through a die to form strands, which are then cut to the desired length.
Extruded diets are moistened and heated with steam, and are forced through die perforations at higher temperatures. They typically expand slightly in the production process, resulting in an airier, less compact, more “kibble-like” texture than cold-pressed pellets.
You’d be forgiven for assuming that the manufacturing process for cold-pressed pellets is, well… cold. But this is a common misconception! While manufacturing temperatures can vary from brand to brand, cold-pressed pellets are usually heated to within a range of 113-176° F (45-80° C), and extruded diets can reach anywhere from 194-302° F (90-150° C) during production. Additionally, the ingredient mixtures used to make cold-pressed pellets often contain pre-cooked ingredients to ensure food safety.
All of this is to say: “cold-pressed” can be a bit of a misnomer, as cold-pressed pellets are heated, just to a lower temperature than extruded diets.
Wait—doesn't high temperature destroy nutrients?
You may have heard that cold-pressed pellets are nutritionally superior to extruded diets because the lower preparation temperatures keep more nutrients whole and usable. The truth isn’t quite so simple.
When it comes to parrot nutrition, specificity is key. The word “nutrients” can refer to anything from protein to minerals to carbohydrates. These are all very different things, and they all react differently to heat.
So, let’s get into the specifics. Below, we’ll go over major nutrient groups to examine this claim.
Carbohydrates are a critical component of a healthy parrot diet. In the body, carbohydrates are broken down into glucose, fueling the cellular activities that keep an animal alive.
The main carbohydrate in plant-based foods is starch. When starch is mixed with water and heated, it undergoes a process called gelatinization. Essentially, the starch granules lose their rigid structure and “melt.” If you’ve ever used a cornstarch slurry to thicken a sauce or soup, you’ve observed gelatinization firsthand. Gelatinization makes starch more digestible (i.e., more usable to the body), and often makes food taste better.
Starches from different plant sources gelatinize at different temperatures, but for the most common starches, the change occurs around 122-176° F (50-80° C). This means that both cold-pressed pellets and extruded diets likely contain gelatinized starch. Again, this isn’t a bad thing, as gelatinization improves both digestibility and palatability.
Have you heard that proteins denature when they’re heated? This is true. And, like starch gelatinization, protein denaturation is a complicated phrase for a not-so-complicated process.
You might think of proteins like beaded necklaces. They’re large, strand-like molecules made up of small building blocks called amino acids. The cells in an animal’s body can’t use proteins as-is—they must be broken up into amino acids to be recycled by cellular machinery.
Denaturation is the “breaking up” of a protein’s larger, overarching structure, and is an important step in disassembling protein into its constituent amino acids. If a protein is denatured, it doesn’t mean it’s being destroyed, or that it suddenly becomes useless. Denaturation happens naturally during digestion, and can be kickstarted with food processing methods like heating. It’s generally agreed that heating protein makes it more digestible and available to the body.
Some studies show that specific amino acids may be rendered less available when cooked at high temperatures. These studies (like this 1983 article) often focus on the amino acid lysine, which may become less available at temperatures in excess of 302° F (150° C). However, it’s important to note that most extruded diets do not reach this extreme of a temperature during manufacturing. Additionally, more recent research seems to contradict these findings.
Minerals are perhaps the simplest of nutrients. They’re elements like calcium and iron which parrots require to keep a variety of processes (like egg-laying and oxygen transport) running smoothly.
Minerals are not heat-sensitive. The stability and structure of a mineral can’t be compromised just by cooking it. Changing the structure of an atom of a given element is something you might worry about in a nuclear research laboratory, not a parrot food facility.
However, we might reasonably worry about mineral availability. Minerals can be more or less available for use in the body depending on other substances in the food. For example, some antioxidants can make it more difficult to absorb minerals like zinc, calcium, and iron. Mineral availability depends largely on a diet’s composition (i.e., what other ingredients are being used in the diet) and less upon its preparation (cold-pressed or extruded).
Parrots require quite a few different vitamins! Not all vitamins are affected by heat in the same way.
Some vitamins, like B2 (riboflavin), B3 (niacin), B5 (pantothenic acid), and B6 (pyridoxine) are relatively heat stable, and are largely retained during cooking. Other vitamins are more heat-sensitive. Vitamin C is a well-known example of a heat sensitive vitamin… but parrots don’t require dietary vitamin C, as they can make their own.
Vitamins B1 (thiamin), E, K, D, and A are among the more heat sensitive vitamins and tend to degrade at higher temperatures. However, some forms of Vitamin A (namely retinol and retinyl palmitate) appear to be much more heat stable than others (β-carotene).
Although high temperatures can degrade some vitamins, bird food manufacturers have ways to bolster vitamin levels and ensure their final product meets a parrot’s nutritional needs. For example, it’s possible to “microencapsulate” vitamins using substances like gelatin and MCT oil, rendering them less heat sensitive. Additionally, vitamin supplements can be added to a formulated diet after it has been produced.
Supplementing vitamins in a formulated diet isn’t inherently bad or indicative of a subpar production process. In fact, both cold-pressed pellets and extruded diets often contain added vitamins like D3. While your parrot can produce their own vitamin D3 through exposure to sunlight, most parrots don’t get enough through this method alone, and depend upon dietary sources to meet their needs. Generally, parrots require a bare minimum of 500 IU/kg of feed. Alfalfa, a common parrot food ingredient, contains only about 25 IU/kg. So, in an alfalfa-based pellet or extruded diet, vitamin D3 (among other vitamins) would likely need to be supplemented regardless of cooking temperature.
If you’re looking for a more in-depth exploration of this topic, you might find this review article helpful, which discusses vitamin retention in extruded pet food.
That’s a lot of info, but how does it help my parrot?
Deciding on a diet for your parrot isn’t easy, which is why we need to step back and look at the science.
At the end of the day, you don’t need to worry that your parrot is missing out just because they’re eating something different than what your friend, neighbor, or coworker feeds their flock. Though snappy marketing copy might try to convince you that cold-pressed pellets are more “natural” or “wholesome,” or that higher cooking temperatures “kill nutrients,” the science shows this just isn’t the case.
The most important thing to consider is whether your parrot’s diet comes from a trustworthy, science-backed manufacturer that prioritizes nutrition and transparency. If you find an option that meets these criteria, you don’t need to fret. A well-balanced formulated diet (along with fresh fruits and veggies) is an excellent way to meet your parrot’s nutritional needs.
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