Melody
Feb 15th 2009, 06:21 AM
As I've been switching my fish over to a non-processed food diet (other than for multi-vitamin purposes), I've had to figure out the difference between the various processing/drying processes. I thought a basic guide might help you navigate your way through as well.
If I sound like I'm contradicting myself, it's because I like to present a complete picture. In other words, we're not on a witch hunt here and therefore all information is shared, not just the wicked stuff that supports my conspiracy theories....lol. The goal is to arm the consumer so you can make the educated decisions that you feel are right for you and your creatures, not convert you to a new religion. That said...
Processing for commercial fish food starts with ingredients like fishmeal which have already been processed at 280 degrees fahrenheit for 60 minutes. THEN those ingredients go on to be heat processed at least once more, often twice+. See my concern here?:err:
So first, the whole point of my mission: What is impacted or virtually eliminated from foods by heat?
- Vitamins
- Enzymes
- Protein & Amino Acids
- Astaxanthin (this is why you see Astaxanthin as an additive to food that already contains ingredients that are high in it)
- Allicin (the most beneficial active component in garlic)
- Uptake (Usually this is a negative impact but with some minerals, for example, the uptake is improved by the heat)
The Processes:
Drum Drying is how fish flakes are made. Moisture is added to dry ingredients to form a slurry, which is applied to a hot drum and the flakes are pealed off.
Spray drying is another way of drying a slurry of feed. Droplets are sprayed and hot air does the drying. It's often used with bioencapsulation. The temperatures typically far exceed the point of boiling but for very short periods. If the manufacturer wishes to lessen the thermal degradation of the product, they can lower the temperatures. This is rarely feasible in pet food production but some do lower the temperatures as a selling point.
Extrusion is a process used to manufacture pellets and typically involves cooking starches in a dry feed with water/steam so the product forms as required. Since starch competes with protein for the water, higher temperatures & more moisture are required to cook the starch in higher protein products. This is complicated further when oil is factered into the equation as it effectively encapsulates the starches, making it that much harder for the moisture to reach them. Combined with the need for longer heat exposure, this results in more nutrient loss than other forms of processing. Although extrusion means more processing, they are making progress in reducing the negative impact on nutrients.
Dehydration:
To preserve food, dehydration is often used. It's a simple concept based on the removal of moisture which prevents bacteria, fungus growth and overall decay. There are several methods of dehydration, including:
Freeze Drying (cryodesiccation or lyophilization) - Dehydrates by freezing the material & heating just enough to allow the water in the product to release as a gas, while reducing surrounding pressure. This method of dehydration preserves overall appearance as well as taste and nutrients. It also offers a longer shelf life. While it is several times more expensive than other dehydrated forms, it contains less moisture so we do in fact get more product by weight, thus reducing the cost.
Air Drying - This can mean many things but for our purposes we'll class items like seaweed here. Seaweed is often dried in open air, protected by a screen. It is then typically disinfected (insect eggs & the like) through a process similar to blanching.
Low Heat Dehydration - Home dehydrators are the best example of low heat dehydration. Unlike commercial operations, the heat is kept low and a fan is used to exchange moisture for dry air. This preserves a much higher percentage of nutrients by comparison to commercial dehydrated products, which destroy a portion of the more unstable vitamins such as Vitamin C.
High Heat Dehydration - Out of necessity, this method is used for mass dehydration at the commercial level. Higher heat is required for efficiency and therefore more nutrients are lost. It still does not compare to the repeated extreme heat that commercial pet food is exposed to, but by comparison to other dehydration methods it isn't ideal.
I hope that this will help you wade through the choices and I'll take this opportunity to remind you that fresh is always best!
---------------------------------------------------------
© Please note: While you are welcome to link directly to this thread,
the contents are copyright Melody McKinnon and cannot be copied.
Thank you for respecting the effort that I have put into our content.
---------------------------------------------------------
If I sound like I'm contradicting myself, it's because I like to present a complete picture. In other words, we're not on a witch hunt here and therefore all information is shared, not just the wicked stuff that supports my conspiracy theories....lol. The goal is to arm the consumer so you can make the educated decisions that you feel are right for you and your creatures, not convert you to a new religion. That said...
Processing for commercial fish food starts with ingredients like fishmeal which have already been processed at 280 degrees fahrenheit for 60 minutes. THEN those ingredients go on to be heat processed at least once more, often twice+. See my concern here?:err:
So first, the whole point of my mission: What is impacted or virtually eliminated from foods by heat?
- Vitamins
- Enzymes
- Protein & Amino Acids
- Astaxanthin (this is why you see Astaxanthin as an additive to food that already contains ingredients that are high in it)
- Allicin (the most beneficial active component in garlic)
- Uptake (Usually this is a negative impact but with some minerals, for example, the uptake is improved by the heat)
The Processes:
Drum Drying is how fish flakes are made. Moisture is added to dry ingredients to form a slurry, which is applied to a hot drum and the flakes are pealed off.
Spray drying is another way of drying a slurry of feed. Droplets are sprayed and hot air does the drying. It's often used with bioencapsulation. The temperatures typically far exceed the point of boiling but for very short periods. If the manufacturer wishes to lessen the thermal degradation of the product, they can lower the temperatures. This is rarely feasible in pet food production but some do lower the temperatures as a selling point.
Extrusion is a process used to manufacture pellets and typically involves cooking starches in a dry feed with water/steam so the product forms as required. Since starch competes with protein for the water, higher temperatures & more moisture are required to cook the starch in higher protein products. This is complicated further when oil is factered into the equation as it effectively encapsulates the starches, making it that much harder for the moisture to reach them. Combined with the need for longer heat exposure, this results in more nutrient loss than other forms of processing. Although extrusion means more processing, they are making progress in reducing the negative impact on nutrients.
Dehydration:
To preserve food, dehydration is often used. It's a simple concept based on the removal of moisture which prevents bacteria, fungus growth and overall decay. There are several methods of dehydration, including:
Freeze Drying (cryodesiccation or lyophilization) - Dehydrates by freezing the material & heating just enough to allow the water in the product to release as a gas, while reducing surrounding pressure. This method of dehydration preserves overall appearance as well as taste and nutrients. It also offers a longer shelf life. While it is several times more expensive than other dehydrated forms, it contains less moisture so we do in fact get more product by weight, thus reducing the cost.
Air Drying - This can mean many things but for our purposes we'll class items like seaweed here. Seaweed is often dried in open air, protected by a screen. It is then typically disinfected (insect eggs & the like) through a process similar to blanching.
Low Heat Dehydration - Home dehydrators are the best example of low heat dehydration. Unlike commercial operations, the heat is kept low and a fan is used to exchange moisture for dry air. This preserves a much higher percentage of nutrients by comparison to commercial dehydrated products, which destroy a portion of the more unstable vitamins such as Vitamin C.
High Heat Dehydration - Out of necessity, this method is used for mass dehydration at the commercial level. Higher heat is required for efficiency and therefore more nutrients are lost. It still does not compare to the repeated extreme heat that commercial pet food is exposed to, but by comparison to other dehydration methods it isn't ideal.
I hope that this will help you wade through the choices and I'll take this opportunity to remind you that fresh is always best!
---------------------------------------------------------
© Please note: While you are welcome to link directly to this thread,
the contents are copyright Melody McKinnon and cannot be copied.
Thank you for respecting the effort that I have put into our content.
---------------------------------------------------------