Q: "You said you would post this=85I hate getting flamed for asking a
simple question. Why do you say modern food is so bad if earlier ferrets
ate bad chow like meow mix and didn't get as sick?"
A: Did I say modern kibbles are bad for ferrets? Are you sure? Oh,
wait, I did say that, didn't I? Gosh, what was I thinking?
Extrusion technology is actually quite simple. You place the raw
ingredients into a hopper (or series of hoppers), and allow the food to
be introduced into a tube, where it is transported towards a die by one
or more carefully designed screws, not unlike the type used to screw two
pieces of wood together, only much larger. The screw(s) mix the food and
transport it down the tube to the opposite end, where it is forced out a
die. Because the hole in the die is much smaller than the diameter of
the tube, great pressure and heat are generated just before the food
exits the extruder. As the food exits the die, the pressure drops, and
as anyone who has taken basic chemistry knows, place heated water under
great pressure, then suddenly drop that pressure, and the water will turn
to vapor and flash off. In this case, escaping water vapor expands the
dough and leaves behind a cooked, dry, hard biscuit. The same thing
happens when you make popcorn: the hard outer shell contains the heated
water to a point that, when exceeded, causes the outer covering to split.
The water suddenly turns to vapor, expanding the interior of the corn,
and flashes off, leaving behind a dry product that when salted and
buttered, becomes ambrosia. Yum!
The angles and depth of the screw blades are varied to produce various
amounts of mixing, shear, and friction. As the screw(s) turns, the food
can be mixed, compressed, heated, sheared, melted, chemically changed,
and even cooked. Some of these reactions are predictable; others are
uninvestigated, or even harmful. For example, under extrusion, some
harmless foods can be converted in carcinogenic feeds because of specific
types of oxidative reactions, reactions with exposed extruder metals (Fe,
Al), formation of free radicals, and lots of other stuff only a demented
biochemist would love. Inedible starch- -cellulose- -could react with
various nutrients, changing the way they are absorbed into the body.
Edible starches that are typically hard to digest can be sheared and
fragmented, making it quite easy for the body to absorb and convert to
sugar. Generally, extrusion technology causes a denaturing of protein
and gelatinization of starch so that both are easier to digest.
Many things are extruded (Cherrios, Cheetos, Cheese Balls), and depending
on the exact process, can be extruded, remixed for additional extrusion,
or even baked or fried. The temperature and pressure can be adjusted so
the same die and screw produce different products. Depending on the
origin of the ingredients, significant differences can exist between
batches of feed made in the same extruder, under the same conditions.
You cannot make a direct comparison of old extruded foods to modern
ones, even if you have a list of their basic ingredients. The reason is
without knowledge of the exact screw mechanism, pressure and heat in the
die chamber, and turning speed of the screw (among other factors), you
cannot predict the exact chemical changes done to any particular
formulation.
I too have noticed what might be considered discrepancies in the health
of ferrets eating the crappy foods a dozen years ago compared to those
eating modern formulations today. I discount the differences for the
most part because of their anecdotal nature. However, some comparison
MAY have value. For example, Meow Mix may have had a lot more starch
included in the formulation, BUT, if that starch wasn't as gelatinized
during extrusion, the actual amount of digestible starch might be LESS
than in modern formulations. Excluding problems of micronutrient
malnutrition (solved with supplements), Meow Mix could have actually
been healthier than modern feeds because of the lowered caloric energy
available to the ferret per consumed quantity of feed.
The other reason I ignore the Meow Mix "phenomenon" is due to modern
formulations, the source of the ingredients, changes in extrusion
technology (pressure, heat, friction, shear, exposed metals, die shape,
screw pitch and depth, etc.), and even the source of the water used in
mixing are ALL uncontrolled variables. Because of the difficulty of
controlling these factors, you can cite as many anecdotal stories as you
like, it still doesn't make the feed comparable to modern feeds. Are
modern diseases due to a change in formulation? Are they due to a change
in extrusion technology? What about oxidative reactions with water
containing reactive minerals? Are the differences in disease real, or
just an epiphenomenon of poor veterinary diagnosis or awareness? Are the
anecdotes valid: are the memories reflecting a true event, or just the
perception of one? See the problem? Without a handle on the variables,
comparisons of earlier kibble formulations are moot.
Personally, I suspect Meow Mix used a lower quality (cheaper) starch
which wasn't denatured as well during the extrusion process, making it
less effective in converting hard-to-digest starch into easy-to-digest
starch. Easy to digest starch translates as caloric energy. It could
mean the early Meow Mix might have been a calorie restrictive feed
compared to modern ferret feeds. As a caloric restricted (CR/DR) food,
it would have extended lifespan, reduced the incidence of tumors, and
helped lessen or prevented disease. Maybe the anecdotes are right, and
years of feeding a crappy, calorie restrictive food is evidence dietary
restriction works. It may just be another hypothesis, but at least it
has theoretical and practical merit. Still, it is an unprovable
hypothesis unless someone has a collection hermetically sealed boxes of
the stuff for analysis, as well as access to the formulation records
(origin, quality), and extruder records. Or, is it unprovable? It could
be someone is investigating the issue as we speak....
Bob C
[Posted in FML issue 3962]
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