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[ EN ]



This invention relates to the treatment of grape marc and in particular is directed to both a method of treating grape marc and its constituent materials, and products as a result of such method.


Currently very large quantities of marc, which is the result of crushed grapes including skins and seeds, result from the wine industry.

There has been some use of marc as cattle food but such use thus far has not been highly regarded. For instance, material is sold at a current price of about AU$20.00 per ton and it is generally regarded by farmers as "trash" food.

The difficulty has been that it has been generally not seen how such material could be further handled that would be both technically viable and economically profitable.


An object of this invention is to propose both a method and resulting product which can provide an economic and therefore profitable return from grape marc.

I have observed that grape marc discarded from a winery or from a subsequent crushing process, if left, develops moulds which make the material less useful as cattle food.

Further however, I have observed that it would be very useful indeed if the components within marc could be separately recovered in a way that provided economically useful product in each case.

Accordingly, what I propose is that the marc which especially contains both seeds and skins should be first subjected to drying where the drying temperatures are selected so as to not excessively degrade the skin component within the marc. In particular, charring or burning of the skins must be avoided, since this causes the resulting feed to be rejected by cattle.

Such a temperature has been found to be approximately 90°C and accordingly, there is proposed a first step in the method for economic exploitation of marc which is to subject the marc to a drying process where the temperature of the seeds and skins is kept below and at least be not substantially greater than 90°C whereby to maintain a useful quality of grape skins in the dried mixture resulting from the marc.

In preference, such drying is to an extent that there is 12% or less of water remaining by volume in the resultant combination.

The moisture content of the seeds within the mix may be somewhat higher, being perhaps 12-25%.

In preference, subsequent to drying, there is provided the step of then effecting a separation of grape seeds from the now dried but not degraded skins.

A significant advantage now arises with this, namely, it is found that with the substantially dried product it is relatively straightforward and not difficult to now separate the seeds from the skins and direct the respective materials into different treatment programs.

Such separation is now in accordance with known techniques but can include selective aerodynamics separation.

From this step then, these skins in preference are directed to a hammer-mill where the material is shredded and is now firstly sufficiently dry for storage and
furthermore is hereinafter suitable for cattle food where it can be sold for a significantly higher return than has been available for the original untreated product.

Typically, such a recovery in economic returns has been estimated at AU$120.00 per tonne for this material.

Separately from this, the seeds, which have been to some extent dried anyway, in preference, are further dried so that as seeds now being separate from the skins they are further dried so that they have a moisture content by volume of not more than 12%.

With such further drying, it has been found that the seeds can now be stored without significant deterioration over at least a medium term.

In preference, the seeds are then treated by crushing so that grape seed oil can then be recovered as a cold pressed oil.

This indeed is of great value because hitherto, grape seed oil has been generally derived by solvent extraction which is considered by some at least to be a less preferred technique.

It is estimated that a return of AU$3000.00 per ton ensures that this to is a profitable recovery method.

In preference, having now grape seeds that can be stored over a longer period, means that this material is available from time to time for on-call crushing as it is needed so that the material itself can be available therefore in an ongoing fresh status.

As can now be seen, this now results then in firstly separated grape skins which as a result of this method have improved value and also resultant materials at each stage of a method each of which are a subject of this invention.


For a better understanding of this invention, it will now be described with the assistance of drawings wherein:

Figure 1 is a flow diagram showing the respective steps that are used in the preferred embodiment, and

Figure 2 illustrates these steps in still a schematic but more graphic form.

Figure 3 is a semi-diagrammatic representation of a further embodiment of the invention.


Referring then to the drawings, the starting material is grape marc.

Such marc can either be material directly recovered from a winery after crushing or it can be material resulting from further treatment which may occur after additional pressings with however in each case moisture traditionally still somewhat over 12%, being likely to be in the range of 50-60%, and comprising substantially skins and seeds.

This is shown at 1 and is historically considered as trash stock feed and will traditionally be essentially discarded.

Such material is extremely vulnerable to mould developments such as white mould and blue mould and this further inhibits its value, especially for cattle feed.

In this embodiment, such material is treated promptly subsequent to any primary or secondary crushing process by being subjected to a drying process where the temperature of the drying is kept so that it will not be above a temperature at least in a sustained or substantially effective way that will unnecessarily damage the skins in the product.

This has been found to be 90°C in experiments so far and in this case, the material is fed into rotary tumblers through which air at approximately 90°C is directed.

Both the amount of air, a length of drying cylinder and any rolling slope are all selected so that firstly the material being dried will be subject to this relatively gentle drying process and generally will not be subjected to temperatures higher than 90°C. The test here is that the skins remain in a useful form for subsequent purpose as cattle food.

It has been found possible to subject the mixture to a significantly higher temperature while wet. In a further embodiment, air

The result itself is measured by the extent of degradation of the skins and the temperature of "90°C" is given as a current estimate of the type of temperature that is found to be appropriate in the experiments thus far.

Clearly, lower temperatures could also be used and as is generally known, there are other forms of drying including very low temperature drying techniques where air is evacuated so as to effectively lower the vapor pressure point for removal.

All of this is therefore directed not so much to the temperature as to the concept that there is provided a lower temperature drying effect which subsequently provides both advantage for maintaining in a commercially useful way the skins for subsequent use and allows for a more efficient and easier separation of the skins from the seeds.

The drier in this case is shown at 2 and directs the output now to a separator 3 where seeds are directed from this along path 4 and the skins are directed along path 5.

The separation process can again be achieved in different ways but in one technique, there is proposed an aerodynamic separation technique in which there is provided a counter flow so that the materials are introduced into an air flow stream where the lighter now substantially dried skins can be directed differentially as compared to the seeds.

Such aerodynamic techniques are generally known but have particular application in this case especially now that the materials have been treated by this preliminary drying.

the resultant separated skins are now directed along outlet 6 by an airflow in a conduit into a hammer mill 8 which shreds the skins and the shredded material is then directed into overhead storage bins 9 from where they can be discharged from time to time into distribution vehicles 10 for delivery to outlets.

The economic advantage for this arrangement is that such product is currently considered to be economically worth AU$120.00 per ton in that it is not subject to at least to any significant degree to contamination which otherwise spoils marc such as moulds. Further it is considered to be highly nutritious for cattle.

Further however, the seeds that are now separated are directed along outlet path 4 into a further drying chamber at 11 so that the seeds are brought back to a moisture content not exceeding 12%.

This further drying ensures that the material can now be stored over a longer period and can be subject to crushing and extraction of grape seed oil as is desired.

A further embodiment of the process is shown semi-diagrammatically in Figure 3.

Marc is loaded by a loader 30 into a hopper 31 which feeds into a primary drier 33. Air is heated by a furnace and fan apparatus 32, which then directs hot air into the primary drier 33. The temperature of this air is variable but may be quite high, as high as 600 C.

The primary drier is a rotating drum, in this embodiment some fifteen metres long, which is angled downward from the loading hopper end 45 to the marc exit end 46. The marc and the heated air progress down the drier, with the moisture content of the marc and the temperature of the air reducing as they progress. At exit, the moisture content of the marc is about 12%, and the temperature at exit is about 79 C.

The dried marc then proceeds from the exit 46 of the drier, via elevator 34 and screw conveyor 35 to the seed separator 36. The marc being now substantially dryer than has been the case in prior used processes, seed separation occurs with much greater efficiency.

From here, the seeds progress along path 38 to a seed drier 39. The seeds, which may still have a moisture content betweenl 2-25%, are further dried to a moisture content below 12% and then proceed to storage hopper 41 for later processing at call.

The marc, now consisting almost entirely of only skins, travels by path 37 to a hammer-mill 40. The output of the hammer-mill is a substantially denser product, which now proceeds to storage hopper 42 for storage and for later use as cattle feed. The product is now of sufficient dryness to allow for medium term storage without mould or deterioration problems.

The high temperature gradient between the marc at ambient temperature and the heated air at the hopper end 45 of the drier serves to rapidly drive off water from the marc. The skins and seeds obviously do not reach such high temperatures while they have a high water content.

Currently, grape seed oil especially cold pressed oil which is recovered without solvent extraction, is very valuable indeed and current prices in the approximate vicinity of AU$3,000.00 per tonne are available.

Accordingly, the seeds as now dried sufficiently for longer-term keeping and are directed again to storage and transport to where they might from time to time be further crushed for cold pressed oil recovery.

What can now be seen is that by use of the method discussed, material that overall was going to bring only a very small economic return can now be converted by methods which are of themselves not especially expensive to very high value materials.

Further however, material which previously would require often relatively high cost disposal, is now converted to provide substantial benefit and furthermore, the material can be processed on current estimates to make a significant profit.

Considering the very large quantities of discarded marc that exists both in Australia and in other countries, this invention is considered to be of very high value.

Although the invention has been herein shown and described in what is conceived to be the most practical and preferred embodiment, it is recognised that departures can be made within the scope of the invention, which is not to be limited to the details described herein but is to be accorded the full scope of the appended claims so as to embrace any and all equivalent methods, devices and apparatus.