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<pre>Guido, Couldn't agree more

If there are people doing as you say and misusing the "Two Phase" systems in
a way that they were not designed for then lets not all get tarred with the
same brush

Regards

Mike

-----Original Message-----
From: Guido Costa [mailto:costa@mweb.co.za]
Sent: 13 November 2001 07:43
To: OliveOil@yahoogroups.com
Subject: Re: [OliveOil] "true cold pressed"


George, I must take issue with you on a number of points:

Firstly, the "two-phase" centrifuge was introduced primarily to reduce the
problem of the water-soluble polyphenols being leached from the oil. This
was certainly a drawback of the old three-phase systems, which not only
created substantial soluble waste, but detracted from the quality and
character of the oil (not to mention the water consumption).

However, your statement that most "two-phase" systems are being run as
"three-phase" is rather sweping. Not all olive oil producers are involved in
producing olio sansa (pomace oil), and thus the soggyness of the solid waste
from the two-phase systems is not an issue for us.

Obviously you chaps have a pomace oil industry to support. I sincerely hope
you reserve this oil only for making soap and candles. The worldwide problem
of benzo-alpha-pyrene contaminant in pomace oil (the carcinogenic,
genotoxic, neurotoxic compound found in many of these residue oils) most
probably originates from the aggressive drying of this soggy pomace or sansa
(prior to the solvent extraction stage). BaP is a Polycyclic Aromatic
Hydrocarbon, which is formed during the incomplete burning of organic
matter, and has been found in pomace oils from all major producer countries,
including those from Greece (at up to 60 times the maximum permissible
level).

I'm sure that there are many producers out there, who, like ourselves, are
not involved in producing olive pomace oil, and who are operating their
systems the way they were designed to operate.

Over the last 70-odd years, we have used hydraulic presses, surface-tension
extraction systems and continuous decanters. To my mind, based on our
specific experience, there is nothing to touch the modern, well-designed
decanter (or centrifuge). It is a far more hygienic system, easy to clean,
and to keep clean. But like any other system, must be operated properly. We
run our system such that the pulp never exceeds 28 degrees C, nor do we
churn the pulp unduly. Whether the oil is pressed out by pressure or
centrifugal force is not the issue. The problem with the presses is that it
is virtually impossible to keep the press mats clean. Unless one very
vigourously steam-cleans the mats after every pressing (and this is totally
impractical), one is bound to be building up a contamination of steadily
increasing rancidity and other off-flavours in the mats. Try looking at the
mat fibres under a microscope, and see what I mean. Or just smell the mats
in many of these hard-core traditionalist mills.

As far as I am concerned, the debate is not between presses and centrifuges,
but between stone mills and hammer mills. Both have advantages and
disadvantages, and I'm not yet convinced, although the new hammermills seem
to be improving rapidly. It would be interesting to hear from those that
have experience in both.

Regards,

Guido Costa




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