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<pre>I would like only to invite people to some more prudence im making statements
about processing issues.
Domenico stated that one should process at 25 C. It is neither correct or wrong.

One should look at a few things:
- Some studies have shown that polyphenol levels are stable during the malaxing
process up to 31 - 32 C. For more infomation dig out the studies made by Prof
Amirante from University of Bari. So would it be neccessary to process at 25C
???
- The viscosity of the oil changes logarithmically with the temperature. So by
processing at 25C you will make things much more complicated if you use
centrifugal technology to extract your oil. So, would it be necessary to look
for troubles ?
- The result of such a low temperature will be a reduced capacity of the
equipment and / or more losses. This can be fine for organic processors in niche
market but is not necessarily the best for everybody. Lets not forget that the
popularity of olive oil has been developed thanks to massive plants of 2 - 6
tons/h, mainly in Spain. Not everybody can afford the super super oil of niche
markets.
- Malaxing issues are actually very complicated and should not be simplified too
much.
A malaxer is a heat exchanged and its design is the result of history, market
requirements and competition. It is in any case a very inefficient device from
engineering point of view.
The heating of the paste is obtained by contact with the wall temperature, right
? One could reach 25 C in a very short time using very high wall temperature
like 50 C. The results of this would be the local evaporation of aromatic
components. This allows you nevertheless to use smaller malaxers and have a
cheaper machine to sell (from equipment supplier point of view)
The better way to do it to have a wall temperature close to the desired paste
temperature. Usually a 5C temp. difference will do but it will depend a lot on
ambient temperature (or olive storage temp)
Beside that malaxing time can be of dramatic effect. Overmalaxing will be
detrimental to the total polyphenol level and will increase the extracted
chlorophyll amount. Many people confuse bitterness and quality and tend to
believe that the bitterness given by chlorophyl is a good attribute and buy such
oils. I have even heard some equipment supplier recommending to block partially
the defoliator to increase the amount of leaves going into the paste to give
that bitterness.
To come back to the wall temperature argument, having to malax with a low temp
difference requires longer malaxing time and increase the malaxer volume
requirement leading to price increase on the machinery. Can everybody afford it
?
In short malaxers and malaxing parameters are a compromise between many
manufacturing, user and olive fruit related aspects. The olive fruit aspects
being so geography specific any strong position should be avoided as there
nothing like absolute truth in olive related matters, there are only gray areas
some darkers than others....

Regards,
Dessss


----- Original Message -----
Wrom: CMHVIBGDADRZFSQHYUCDDJBLVLMHAALPTCXLYR
Date: Wed, 19 Jun 2002 19:11:04 +0200
To: <OliveOil@yahoogroups.com>
Subject: R: [OliveOil] Filtration of oil


> Dear Julie,
>
> If you have in mind to produce high quality olive oil, you need by the
> others to:
>
> 1) do an early harvest (when the fruit it is half green and half brown)
> 2) press at temperature below 25°C and within 24 our from the harvest
>
> Well, in this case the oil will show a very low free acidity and peroxydes
> content and also high concentrantion of polyphenols.
>
> This oil need at least 2 months to depositate and it is also reccomended to
> operate more than one decantation.
>
> Alternatively, I suggest you to filter the oil in a stainless stell tank
> containing cotton as filtering surface.
>
> There is an other choice that is the use of forced filtration obtain by
> pressure and paper filter. I suggest you to do not use this metod because
> many substancies responsible for the oil's organoleptic features are stopped
> by this method.
>
>
> You also choose to produce unfiltering oil. It is now well known that the
> unfiltered oil is organoleptically the best choice for the fresh use, but
> the little particles of fruit may undergo during time to organic
> decomposition whic in turn increase free acidity, peroxydes and so on.
> Therefore the oil quality decrease.
>
> I suggest to consume unfiltered oil within 8 moths from the production date.
>
> This discussion it is supported by chemical and organoleptic oil analysis
> which we have done many times.
>
>
> Regards
>
> Marco Bettini
> Organic Farm Domenico Bettini
> http://www.aziendabettini.com
>
>
>
>
>
>
>
>
>
>
> -----Messaggio originale-----
> Da: juliemlloyd [mailto:lloyd@...]
> Inviato: lunedì 17 giugno 2002 15.14
> A: OliveOil@yahoogroups.com
> Oggetto: [OliveOil] Filtration of oil
>
>
> I'm interested to hear any comments on treatment of oil after
> pressing.
> Do most of the members of this group filter their oil? If so, what
> type of filters do you prefer? How long do you leave the oil to
> settle?
> As a novice to oil production, I would appreciate your opinions.
>
> Julie Lloyd
>
>
>
>
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