Melody
Oct 28th 2007, 12:09 AM
I have been more and more dismayed as I study the effect of heat processing on nutrients, leaving most commercial foods to amount to whatever minerals that survive. Even the synthetic vitamins that are added are only effective if they are added after the heat processing. Heat breaks down vitamins, amino acids and results in negative cross-linkage of proteins. In fact, Encyclopedia Britannica states "Cooking destroys protein to make it practically useless". The amino acids digestibility is markedly reduced by heat processing, with the broken chains having toxic potential.
Certainly the allicin from the garlic isn't going to survive heat processing.
Whole Dog News sums it up nicely...
When food is cooked above 117 degrees F for three minutes or longer, the following deleterious changes begin, and progressively cause increased nutritional damage as higher temperatures are applied over prolonged periods of time:
proteins coagulate
high temperatures denature protein molecular structure, leading to deficiency of some essential amino acids
carbohydrates caramelize
overly heated fats generate numerous carcinogens including acrolein, nitrosamines, hydrocarbons, and benzopyrene (one of the most potent cancer-causing agents known)
natural fibers break down, cellulose is completely changed from its natural condition: it loses its ability to sweep the alimentary canal clean
30% to 50% of vitamins and minerals are destroyed
100% of enzymes are damaged, the body’s enzyme potential is depleted which drains energy needed to maintain and repair tissue and organ systems, thereby shortening the life span.117 degrees for three minutes... Keeping in mind that the average 'meal' used in pet food is cooked at 280 Fahrenheit for 60 minutes, and then heat processed again to mold it, that doesn't leave a whole lot left of the original nutrition content.
Bio-encapsulation and low heat processing makes far more sense to me. Bioencapsulation also serves as a means of preservation, making the less desirable methods of preservation unnecessary.
There is an excellent article here (http://www2.hawaii.edu/~delbeek/delb16.html) that you can use to spot the signs of vitamin deficiency in fish. Remember that colour and grossly exagerated growth rates are not necessarily an indicator of good health. Factors such as a fully functional immune system is far more indicative. You can improve any fish's colour and increase the growth rate with Krill and Spirulina alone, but that doesn't mean a diet of those two foods only would be good for the fish.
Nothing beats or even compares to fresh food, with freeze-dried and dehydration coming in as a close second. If you have to feed a commercial food, and most of us do for the sake of convenience, try to find one that doesn't heat-process the food into useless powder which is then heat processed again to take its final form.
At the very least, find a commercial food that is fortified after the heat process and includes extra fortification like the Omega complex. View it as a multi-vitamin and balance the intake of commercial foods with fresh foods for optimum nutrition.
Beware of the hype. No matter how they try to hype up the ingredients, they might as well be fortified baby powder if they're over-processed and preserved in carcinogens. They can say that an ingredient is good for fish and why, but the sources of that information aren't talking about an over-processed pile of dust. Your best protection from hype is education about the wild diet of your fish, the nutritional content of food and just what is left of all of the wonderful ingredients that a commercial food starts with after it is processed to infinity. They aren't lying about the benefits of these ingredients, but they're not telling you the full story either.
Addition:
I've been looking into spray-drying as it is one of the processing methods used on seaweed (freeze-drying is also used for seaweed).
Although spray-drying uses heat, it isn't as high as the temperatures used on fishmeal and most importantly, its a flash of heat that dries the seaweed before it hits the wall. The length of time that a food is exposed to heat greatly impacts the nutrient loss. It can also be dried at much lower temp's should they prefer it that way. While not as good as freeze-drying, spray drying is by far the preferred method of heat processing when it is the only processing endured.
So what about manufactured fish foods that are spray-dried? Well, if they use processed ingredients like fishmeal then you're only skipping the final heat processing. The damage has already been done to the ingredients that were heat processed. If the ingredients include spray-dried or freeze-dried items, using spray-drying as the final method of processing will result in higher vitamin retention for those particular ingredients. Less heat in the final stage is better than nothing, but it won't count for much unless all or many of the ingredients were also low-heat processed. That brings us back to the trick they all use - just because the ingredients would be good for fish if they were fresh, doesn't mean they're good for fish when they've been over-processed. Don't expect them to admit that anytime soon though.
Another question we should be asking, is how the food is sterilized. If heat is used for that too, it means there's a good chance that manufactured foods go through at least THREE stages of heat processing. It also means that even low-temp methods of processing may have included an initial heat sterilization. The temp's & exposure requirements are much less than that which is used on fishmeal, but its still an impact. Other methods of sterilization include chemical and a newer organic method of using pressure. Of course, they won't be able to answer this or other questions if they don't produce the food in-house.
I talk about vitamins most because they are the most unstable. Our present understanding is that minerals withstand high temp's much better overall, although their bioavailability can still be impacted in either positive or negative ways.
We still don't know enough about the how processing effects bioavailability to do much more than offer an educated guess at this point, even in humans. It is a crucial factor in deciding what to feed our fish and other animals though. It doesn't matter how much protein a can of food says it contains, for example, if the creature eating it can't utilize it because the processing has rendered it useless.
We see bioavailability issues in fresh food too, but we know a lot more about that. Spinnach is a well-known example. It is packed with calcium but the mineral is rendered useless by the oxalates the vegetable contains. Those we can't do anything about, but we have a choice when it comes to processing methods.
I can understand how those who no longer feed manufactured pet foods arrived at the conclusion that it is worth the effort. Between the processing, chemicals and fillers, I'm pretty much sold on going that route myself. What's the point of wasting my money on a synthetic multivitamin? I will be feeding fresh, frozen, freeze-dried and low-heat processed commercial foods from here on in. Yeah, a lot of fish do fine being fed commercial foods only. If those foods contain ingredients that boost colour and extra synthetic vitamins, they may even seem to do very well on that diet. However, they can't help but benefit from natural sources of nutrition, especially since we still don't know the whole story of their requirements. The ultimate pet food will never be an over-processed one, period.
Good health to you and your fish!
---------------------------------------------------------
© 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.
---------------------------------------------------------
Certainly the allicin from the garlic isn't going to survive heat processing.
Whole Dog News sums it up nicely...
When food is cooked above 117 degrees F for three minutes or longer, the following deleterious changes begin, and progressively cause increased nutritional damage as higher temperatures are applied over prolonged periods of time:
proteins coagulate
high temperatures denature protein molecular structure, leading to deficiency of some essential amino acids
carbohydrates caramelize
overly heated fats generate numerous carcinogens including acrolein, nitrosamines, hydrocarbons, and benzopyrene (one of the most potent cancer-causing agents known)
natural fibers break down, cellulose is completely changed from its natural condition: it loses its ability to sweep the alimentary canal clean
30% to 50% of vitamins and minerals are destroyed
100% of enzymes are damaged, the body’s enzyme potential is depleted which drains energy needed to maintain and repair tissue and organ systems, thereby shortening the life span.117 degrees for three minutes... Keeping in mind that the average 'meal' used in pet food is cooked at 280 Fahrenheit for 60 minutes, and then heat processed again to mold it, that doesn't leave a whole lot left of the original nutrition content.
Bio-encapsulation and low heat processing makes far more sense to me. Bioencapsulation also serves as a means of preservation, making the less desirable methods of preservation unnecessary.
There is an excellent article here (http://www2.hawaii.edu/~delbeek/delb16.html) that you can use to spot the signs of vitamin deficiency in fish. Remember that colour and grossly exagerated growth rates are not necessarily an indicator of good health. Factors such as a fully functional immune system is far more indicative. You can improve any fish's colour and increase the growth rate with Krill and Spirulina alone, but that doesn't mean a diet of those two foods only would be good for the fish.
Nothing beats or even compares to fresh food, with freeze-dried and dehydration coming in as a close second. If you have to feed a commercial food, and most of us do for the sake of convenience, try to find one that doesn't heat-process the food into useless powder which is then heat processed again to take its final form.
At the very least, find a commercial food that is fortified after the heat process and includes extra fortification like the Omega complex. View it as a multi-vitamin and balance the intake of commercial foods with fresh foods for optimum nutrition.
Beware of the hype. No matter how they try to hype up the ingredients, they might as well be fortified baby powder if they're over-processed and preserved in carcinogens. They can say that an ingredient is good for fish and why, but the sources of that information aren't talking about an over-processed pile of dust. Your best protection from hype is education about the wild diet of your fish, the nutritional content of food and just what is left of all of the wonderful ingredients that a commercial food starts with after it is processed to infinity. They aren't lying about the benefits of these ingredients, but they're not telling you the full story either.
Addition:
I've been looking into spray-drying as it is one of the processing methods used on seaweed (freeze-drying is also used for seaweed).
Although spray-drying uses heat, it isn't as high as the temperatures used on fishmeal and most importantly, its a flash of heat that dries the seaweed before it hits the wall. The length of time that a food is exposed to heat greatly impacts the nutrient loss. It can also be dried at much lower temp's should they prefer it that way. While not as good as freeze-drying, spray drying is by far the preferred method of heat processing when it is the only processing endured.
So what about manufactured fish foods that are spray-dried? Well, if they use processed ingredients like fishmeal then you're only skipping the final heat processing. The damage has already been done to the ingredients that were heat processed. If the ingredients include spray-dried or freeze-dried items, using spray-drying as the final method of processing will result in higher vitamin retention for those particular ingredients. Less heat in the final stage is better than nothing, but it won't count for much unless all or many of the ingredients were also low-heat processed. That brings us back to the trick they all use - just because the ingredients would be good for fish if they were fresh, doesn't mean they're good for fish when they've been over-processed. Don't expect them to admit that anytime soon though.
Another question we should be asking, is how the food is sterilized. If heat is used for that too, it means there's a good chance that manufactured foods go through at least THREE stages of heat processing. It also means that even low-temp methods of processing may have included an initial heat sterilization. The temp's & exposure requirements are much less than that which is used on fishmeal, but its still an impact. Other methods of sterilization include chemical and a newer organic method of using pressure. Of course, they won't be able to answer this or other questions if they don't produce the food in-house.
I talk about vitamins most because they are the most unstable. Our present understanding is that minerals withstand high temp's much better overall, although their bioavailability can still be impacted in either positive or negative ways.
We still don't know enough about the how processing effects bioavailability to do much more than offer an educated guess at this point, even in humans. It is a crucial factor in deciding what to feed our fish and other animals though. It doesn't matter how much protein a can of food says it contains, for example, if the creature eating it can't utilize it because the processing has rendered it useless.
We see bioavailability issues in fresh food too, but we know a lot more about that. Spinnach is a well-known example. It is packed with calcium but the mineral is rendered useless by the oxalates the vegetable contains. Those we can't do anything about, but we have a choice when it comes to processing methods.
I can understand how those who no longer feed manufactured pet foods arrived at the conclusion that it is worth the effort. Between the processing, chemicals and fillers, I'm pretty much sold on going that route myself. What's the point of wasting my money on a synthetic multivitamin? I will be feeding fresh, frozen, freeze-dried and low-heat processed commercial foods from here on in. Yeah, a lot of fish do fine being fed commercial foods only. If those foods contain ingredients that boost colour and extra synthetic vitamins, they may even seem to do very well on that diet. However, they can't help but benefit from natural sources of nutrition, especially since we still don't know the whole story of their requirements. The ultimate pet food will never be an over-processed one, period.
Good health to you and your fish!
---------------------------------------------------------
© 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.
---------------------------------------------------------