Why does dry pet food need antioxidants?
Any
product which contains fat, and which has contact with the air stands a good
chance of 'going off' after a while, as the oxygen reacts with the fat molecules
- this process is called oxidation, or we tend to think of it as fat going
rancid. (Canned dog food is protected from oxidation by its airtight storage)
RANCIDITY is the oxidation(decomposition) primarily of unsaturated fatty acids(containing one or more bonds, such as oleic, linoleic, and arachidonic acids) resulting in disagreeable flavors and odors in fats and oils (stale chip fat smell). This occurs slowly and spontaneously and may be accelerated by light, heat and certain minerals. Once the reaction is initiated, it becomes autocatalytic (i.e. it just keeps on going!) and proceeds unabated until the reactants are completely exhausted.
Oxidation of the fat decreases the nutritional quality of the food, makes it less palatable to the pet, and can even make it unsafe to eat (Oxidation of unsaturated fatty acids yields ketones and free fatty acids that are usually unpalatable and potentially injurious. It takes as little as 0.05% of the fat to react with oxygen to produce rancidity.)
Since most pet food contains high level of fat and fat-soluble ingredients (including vitamins A and E), it is critical to prevent oxidation to maintain quality, nutritional value and palatability.
The meat meal and fats used in pet food are subject to a lot of processing and mechanical damage before they get to the factory (During rendering, the inherent animal cellular defense mechanisms are disrupted or destroyed), and during that process and storage they will start to deteriorate due to oxidation - they will go rancid - unless something is done to stop or slow this change from happening.
Rancidity is usually expressed as a 'Peroxide Value' or PV, and there is much debate as to what is the point at which a fat goes rancid, as you can see from the extract below:
| '..Nutritionists and buyers have
arbitrarily established maximum initial PV levels of between 5 and 20
meq O2/kg of fat as acceptable. The origin of these standards is unknown.
Carpenter et al. (1966) suggested the source to be from the footnote
to a table in a paper published in 1941 (Gray and Robinson). The footnote
gave analytical data for a series of meat meal samples and included
the comment: “a fat with a peroxide value of more than 20 is definitely
rancid”, even though they concluded later in the paper that such
“rancid” meat meals may be fed to animals without harm.' |
So how do we stop fats going rancid?
As far as the majority of the pet food industry is concerned, your pet food will be preserved with one or more different antioxidants - either natural (Vitamin E, C or Tocopherols) or not (BHA, BHT, Ethoxyquin or similar) or a mixture of both types - and the pattern will be something like this:-
| Product 1 Meat Meal and Fats pre-treated with BHA, BHT by supplier.
Ingredient declaration: |
Product 2 Meat Meal and Fats pre-treated with Vitamin E, Vitamin C, Tocopherols or similar by supplier
|
Product 3 Meat Meal and Fats pre-treated with BHA, BHT or similar by supplier
|
'Hang on!' you might say at this point. 'Product 3 contains artificial preservatives!' And of course it does, but because the meat meal and fats were pre-treated before manufacture by the supplier, I think I'm right in saying that you don't actually have to declare them as ingredients (there's a similar rule with human food, believe it or not)
You need to know this! Some companies specify from their suppliers that fats and meat meal do not contain artificial preservatives, others do not. You may not realise this from the ingredient declaration.
Dr. Lisa Freeman, DVM writes 'The problem is that there's no legal definition of "all natural," "preservative free," or similarly named products. Manufacturers define products by what they believe these terms mean. In general, the implication is that no preservatives or artificial colors have been added and that natural preservatives, such as vitamin C or vitamin E, have been used, but this can vary from brand to brand. In addition, although these products may not contain added artificial preservatives, they may still contain low low levels of artificial preservatives that were already in the meat or fat-soluble vitamins obtained from suppliers.'
What are the natural alternatives?
Well, I've mentioned the main ones already, ethoxyquin, butylated hydroxyanisole (BHA), Butylated hydroxytoluene (BHT) are the traditional antioxidants used. You might also see propyl-gallate and potassium sorbate used as preservatives. I asked Royal Canin, Eukanuba/Iams and Pedigree for comments on the system they use. Pedigree are happy using BHA and BHT but offer no expanation as to why they prefer these to more natural alternatives, but I got a very informative reply from Royal Canin who are very upfront about the antioxidants they use and why - full marks for a real spirit of openness. You can read Royal Canin's response here.
Hills have also responded, and although a little clarification is needed, the news for 'natural' is good. They said 'Hill's adds a Natural Preservative System to all Science Plan and Nature's Best dry products. This is to protect against fat rancidity and maintain freshness and flavour. This system consists of a blend of mixed tocopherols (natural antioxidants that are part of the vitamin E family), citric acid (a natural preservative which is synergistic with tocopherols) and rosemary extract, which also has antioxidant properties. Hill's Natural Preservative System enables us to maximise the protection of the fatty acids and fat soluble vitamins within these dry foods and maintain our aim of providing the very best quality nutrition possible.'
This Natural Preservative System will also be added to Hill's Prescription
Diet dry products. Currently new, dry product introductions to this range
contain the Natural Preservative System and the existing products contain
a blend of the food antioxidants BHA and BHT (butylated hydroxyanisole and
butylated hydroxytoluene). These synthetic antioxidants have been widely used
by the manufacturers of human foods and pet foods because they are both safe
and effective. They are most effective when used in combination.'
(I have responded to this by asking if Hills pre-treat their fats and meat
meal naturally or with BHA/BHT (this wouldn't be obvious from the ingredient
declaration) - so far no response, so I'm guessing that route 3 above
is the way they follow!)
Eukanuba were a little more coy in their response 'I would like to reassure
you that our Eukanuba and Iams over-the-Counter range does not contain artificial
antioxidants or preservatives. The EC permitted antioxidants in our diets
are natural preservatives such as Vitamin E, Rosemary Extract, Citric Acid
and Lecithin.'
I might be wrong, but I'm guessing that Eukanuba follow the 'Product
3' approach, with chemically pre-treated fats and meat meal. The reply promised
that my enquiry would be forwarded to their technical department - so I await
further clarification.
Iams new Wellness brand declares no preservatives - so on the basis of all dried pet foods need antioxidants I'm guessing that they also use pre-treated fat and meat meal, maybe coupled with a gas-flushed bag to eliminate oxygen. But then, what happens when the consumer opens the bag? Unless of course they've discovered a miracle new way of stopping fats go rancid?
So let's look at the alternatives and, as importantly, their effects on reducing or stopping the adverse oxidation and rancidity of the product. After all, what we don't want, even if we're committed to the natural route, is a product which not only contains rancid fat but is potentially causing adverse health problems.
Incidentally, did you know that BHA and BHT are already present in a lot of human foodstuffs as well as cosmetics (particularly lipstick and mascara!!?) Read More
| Antioxidant |
Advantages |
Antioxidant |
Advantages |
| BHA BHT Ethoxyquin
|
When ethoxyquin was incorporated
with mixed fats, it took 100 days to reach a concentration of 20 meq/kg
of peroxide (a breakdown product of fats, and a possible point of rancidity
setting in). When alpha tocopherol was used, the same concentration
was reached in only 12 days. Similar data has been found in tests with
vitamins. This means that the ethoxyquin was far, far better at stopping rancidity than the natural alternative by a factor of almost x10. Both BHA and BHT have been used for many years in human food and cosmetics, and their safety has been examined on several occasions. They are considered safe when used within recommended limits.
|
Vitamin E Vitamin C alpha tocopherol
|
No health scares/issues with the antioxidants themselves. These naturally derived antioxidants include gamma and delta tocopherols (which can come as a by-product of soya bean processing), ascorbic acid, citric acid, and lecithin. Gamma tocopherol, however, has only 10% of the biological activity of the alpha form, leading to the question whether use of this product has any biological use as a viable antioxidant at all
|
| Disadvantages |
Disadvantages |
||
Although ethoxyquin has been used in animal feed for more than 30 years, in the last nine years the FDA has received many consumer reports about health problems occurring in dogs that were fed ethoxyquin-containing foods. The FDA Center for Veterinary Medicine states, however, that there is insufficient scientific evidence to show that ethoxyquin is unsafe when used at approved levels or to warrant action against its use in pet foods. A recent study by Monsanto, the major producer of ethoxyquin, indicated that the only problems caused by long-term, moderate-to-high ethoxyquin levels in food were mild increases in blood levels of liver enzymes and an increase in the levels of a normal red-blood-cell metabolite in the livers of lactating bitches, who generally eat more than other dogs. No reproductive abnormalities or other health problems occurred. Both BHA and BHT have been investigated with respect to food safety as these are used in human food. In 2001, the UK Food Standards Agency commissioned a project to develop
methods to assess the health effects from mixtures of food additives.
From an ILSIEurope ADI Task Force report, four food additives were selected
where the This report does not appear to have been made public yet.
|
The main disadvantages seem to be that these products are less effective at controlling rancidity. When ethoxyquin was incorporated with mixed fats, it took 100 days to reach a concentration of 20 meq/kg of peroxide (a breakdown product of fats). When alpha tocopherol was used, the same concentration was reached in only 12 days. Similar data has been found in tests with vitamins. Susan E. Orosz, Ph.D., D.V.M states 'Unfortunately, many pet foods are sitting on the shelf for longer than 100 days and the activity of the natural antioxidants will be reduced or will have expired by the time of purchase and/or use. To compensate for this problem, vitamin E could be added; however, if large amounts are added, this may indirectly affect selenium and/or vitamin D metabolism'
The protective effect of a natural antioxidant may be as little as one-tenth as a synthetic antioxidant. |
Great Deals from Pets at Home own brand
Best Prices for James Wellbeloved Dog Food
Best Prices for Puppy Food
Good Prices on Dog Crates
Save £s on Flea Treatment
Check out our other sites: The Food Lover , Pet Food Choice , Dog Food Review , Keep on Shopping! , A Gift of Flowers , Faith & Worship |
