CA1125199A - Centrifugal separation in wine making process - Google Patents

Abstract

ABSTRACT OF DISCLOSURE

Disclosed is a process for making wine in commercial quantities wherein the skins and seeds of the destemmed grapes are centri-fugally separated from the grape must and left almost entirely free of moisture. The grape must is subsequently enzymatically depectinized. The depectinized grape must is then cleaned of substantially all insoluble colloids and fermented into wine, using only a minimum, if any, of sulfur dioxide or other bact-eriological retractant. The skins and seeds are then separated by wind sifting, or screening, to make usable by-products.
Also, for additional flavor and for red wines, color can be extracted from the segregated skins.

Description

5~99 CE~TRIFUGAL SEPARATION IN I~INE ~IAKING PROCESS
T~CHNICAL FIRLD
This invention relates ~enerally to wine making and more particularly to processes for the commercial production of large quantities of wine, economically.
~ACKGROUND OF PRIOR ART
In the typical large volume, commercial wine making process, the grapes are first passed through a destemmer and crusher and then through presses which re-duce the crushed grapes to a grape must including grapemeats, juice, some remaining skins and seeds. The grape must thus formed contains insoluble collodial matter such as pectin, proteins, micro-organisms, and even dust, and lear and stem debris. The grape must is then fermented lnto wine. In making white wines the grape must is separ-ated as adequately as possible from the skins and seeds, while in red wines the fermentation takes place in the presence of the skins and seeds because the color must be extracted from the skins. Pectin enzymes may be added to the grape must during fermentation to break down the pec-tin.
In pressing the grape must from the grapes, qual-ity compromises must be made. If the pressing is ex-cessive, the seeds are squeezed and the seed oil produces an astringent flavor in the wine. If the pressing is too light, too much wine is lost in the pomace. Even with the best presses the moisture content of the resulting pomace is normally between 50$ and 60~. In order to in-crease the pressing yield, many wineries add commercially availaDle pectic ellz~mes at l,he crusher and leave the rnash for several ~our, to partlally break down t~le pectin, berore passing it throuGh the presses.
The grape must is then passed through one of a variety of separatinG processes, the purpose of which is to separate out, before or cluring fermentation, the in-soluble co]loids from 'he pure juice of the grapes and thereby pro~uce a cleaner, less cloudy juice. The extent to which this separation is successful depends largely on the reflnements of the particular wine making process, and in general, the cleaner the juice the better the wine.
~ here the separation process to which the grape must is subjected does not remove substantially all of the insoluble colloids, as is typical of processes used for less expensive wines, the juice contains considerable quantities of biological contaminates which tend to multiply during fermentation.- If these contaminates are allowed to multiply freely, they spoil the wine. It ls, therefore, typical in a commercial wlne making process for less expensive wines, to retard the growth of the bacterial contaminates by subjecting the fermenting wine to sulfur dioxide.
Two maJor disadvantages occur from this procedure.
First, the bouquet of the wine is largely lost to the foul sulfur dioxide smell. Secondly, the yeast cells which further the full development of the wine are poisoned and lose much of their vigor and character, causing a disequilibrium in the wine which substantially detracts from the quality of the end product.
3 Furthermore, these present processes result in waste products consisting of the intermingled seeds, skins and other insoluble colloids which are substantially valueless and present difficult disposal problems. Also, astringency is injected into the must by seeds smashed in the presses, and fermentation occurs in the presence of much undesirable foreign matter.
Although centrifugal separation of the seeds and skins from the grape must, instead of pressing, has been ~1~'51~39 considered before in wine making, it was abandoned because effective and eco-nomic separation could not be achieved and the resultant grape must was con-sidered too cloudy to use, and in red wines the skins were needed in the grape must to produce the color.
Since many economies, quality and improvements are suggested by ef-fective and economical centrifugal separation of the seeds and skins from the grape must, such as an increase in the volume of juice, avoidance of astrin-gency from crushed seeds, fermentation without biological contaminants and the salvage value of the skins and seeds, a need has long existed for a com-mercially feasible process utilizing this procedure.
BRIEF SUMMARY OF INVENTION
It is, therefore, a major object of my invention to provide a pro-cess for making wine in which the centrifugal separation of the skins and seeds from the grape must is practical, feasible, and economical.
It is also an important object of my invention to provide a process for making wine in which the centrifugal separation of the skins and seeds from the grape must can be carried out prior to depectinization and separation of undesirable insoluble colloids and micro-organisms, thereby providing a more homogenized must for processing.
It is another important object of my invention to provide a process of the type described in which the skins and seeds, after separation centrif-ugally from the grape must, can be readily separated from one another and salvaged as usable by-products.
It is a further object of my invention to provide a process of the type described in which a cleaner, higher grade juice for fermentation can be achieved with no greater processing expense than formerly required.
It is still another object of my invention to provide a process of the type described which can be used with red wines as well as white even though the skins are separated from the remainder of the grape must before fermentation, by extracting the color from the skins after they have been separated, and returning it to 11~5199 the jl~Icc 1~ ;r~
It Is .~ lll a ~l~rtller object of My irlVC-ilt,iOn 'CO
provide a proco;s of the type described which ~rovides a maximum wine q~al;ty.
~ '])ESCRIPTION 0~ DRAI~]ING
__ _ _ _ . _ Trlese and other objects and advantages o~ my invention will be more readily apparent from the follow-ing detailed description of a preferred embodlment of my process which is explained in part by reference to the accompanying drawing of a schematic diagram showing the various steps of my process.
DETAILED DESCRIPTION OF INVENTION
_ _ Referring to the drawing, the numeral 10 desig-nates generally a preferred embodiment of my process.
The process is lnitiated by a grape receiving and de-stemming facility 12 which receives the grapes at the start of the process and separates them from the leaves and stems in a manner well known in the art. The grape receiving and destemming facility 12 is unchanged in my process and any of the presently known equipment for pro-viding these functions will satisfactorily provide the functions in my process.
The next step in my process is the crushing of the grapes to prepare them for separation of the juice.
Again, this step of my process does not differ from the c rushing already commonly used in commercial wine making, and a roller crusher 13 of any well known type is satis-factory.
After crushing, I do not press the grapes but 3 instead, I achieve the grape must by centrifugally separating the skins and seeds from the remainder of the grapes. It is this step of my process which differs most importantly from processes presently used for the commercial production of wine. Particularly, I cause the destemmed, crushed grapes to be delivered to a centri-fugal separator 14 for simultaneously drawlng the juice from the grapes and separating their skins and seeds from the remainder of the grape must. There are a number Or available machines which can satisfactorily perform ~L125199 thls ~ ctll~n, ~ h apprr~r,riatc mr)dilL~atL~ns. Orle such machine is t~e 'ContlA-L~ " s~re~.ning cen~riruf,e rranll-factured l~y S-ieibtec,lnik Or l~.ul`rielm, Gerlnany. This rnachine has a large,conical stainl~ss s~eel ~asket screen whlch rotates at a high .speed. Wit;lin this screen is a conical helicoi~al screw conveyor whlch rotates at a slower speed than the screen. The conveyor barely clears the screen so that the screen is kept open at all times.
~y proper adjustment of the screen speed and size of openings, the axial length and conical incline of the æreen, and the spacing and relative speed between worm and screen, seeds and substantially all the larger skin particles can be retained inside the screen and the grape must drawn off and passed through the screen to such an extent that only 5% to 10~ moisture content remains in the pomace.
A similar machine to the "Conturbex" is the 'Mercone" screening cent~ifuge manufactured by Dorr-Oliver, Incorporated, of Stamford, Connecticut. The "Merconi" machine has a vertical axis rather than hori-zontal as in the "Conturbex", but provides a rotating conical screen and a helical core which rotates at a different speed. Again, by proper design of the machine parameters, such as described above respecting the "Conturbex" machine, a similar result can be achieved.
Still another machine which can provide the de-sir4d result for this step of my process if the "Rietz R D Series Vertical Disintegrator" manufactured by the Rietz Division of Bepex Corporation~ Santa Rosa, Cali-fornia. The Rietz" disintegrator has a stationarycylindrical screen with a generally vertical axis and a rotating core with radially projecting hammers. For example, in a recent experiment at the San Martin Winery, San Martin, California, I passed three tons of a de-stemmed and crushed grape mass through a "Rletz" dis-integrator with a rotor speed of 1200 RPM and a 1/16 inch mesh screen. A retainer ring was placed at the bottom of the screen to slow the passage rate to six tons per hours. The result was a usable grape must and seeds 11~5199 e!ld skins Jltil a mols~ nte,lt of only 8~. Sam~lcs OL
t'r!~,e seed~ and kL~ls )ere tl~en successrully separaled by air clac;sirlca~loll.
I l-~ave th~s establlshed that centri~uges of this type are capable of making a very thorough separation of the skirls and seeds rrom the remainder of the grape must by passing the liquid and srnall solids out of the cen-trifuge chamber while retaining the skins, seeds and larger solids therein. So effective is the separation achieved, that the skins and seeds are almost entirely free of moisture when they are taken from the centrifuge.
How the skins and seeds may be handled after they are taken f-rom the centrifuge in the condition just described, I will disclose later in discussing that phase ~ my process.
In any case, the skins, seeds and larger solids are removed from the centrifugal separation apparatus 14 by an appropriate ~nduit 16, and the remainder of the grape must, liquid ln form, is delivered into conduit 18.
~Jhile it is true that the grape must delivered from the centrifuge 14 will be cloudier than the must delivered from must presses, it can, nevertheless, result in a clean, hlgh quaiity iuice, as I will explain later.
Several important advantages over presses are achieved by the use of the centrifuge. FirstJ the yield of grape must from the grapes is maximized to nearly total, and even the best presses cannot exceed it. Second, pressed seed extract is not released, as is always the case when presses are used, and the undesirable astringent flavor derived from seed oil is, therefore, not dispersed in the grape must. Finally, the skins and seeds are de-livered in such a condition'',hat they are not only separ-ated from the remainder of the grape must, but can be readily separated from one another to produce usable by-products, and permit color and flavor extraction from theskins, as later explained.
The grape must, after the seeds and skins have been separated, is then delivered by conduit 18 to depectiniZing tanks 20 by a pump 22. Here, the grape _7_ 1 1 Z 5199 rnu~ 3t-~ d l)y ~ c~ing 1~ ~o ~Lj~ic~;Jr~ r~g en,.y~î~s wrllle it Is prv~-ct~d frorn o;~.k~atLGn a;id ~r~
by an a~rnosphe~e Or C02 as tau~ht ~n m~J patent nu~i~ber 3,741,770, lssued June 26, 19~3. As suggested ln that patent, the C02 can be readily obtained as a ~ -product from the fermentation vats by conduit 23 and blo,ler 24.
'~nile other known procedures for depectinizlng the must may be used, or depectinizing may be done prior to centrifugal separation, or not at all, ~ prefer the process just described.
After depectinization in the tanks 20, the grape must is delivered to an apparatus for separation Or in-soluble colloids and micro-organisms from the juice. The flotation process described in my said patent 3,741,770 is a preferred means for making this separation, however, other means are available~ such as rotary drum filters, screening centrifuges, desludgers and the like.
As I have previously indicated, the grape must produced in my process is lnitially more cloudy than that 20 which results from most presses. An effective separation procedure is, therefore, particularly lmportant in my process. Although as I have indicated above, a number of separating procedures can be used to do this job, I
prefer the flotation process described in my patent number 3,741,770 because it is particularly efficient for this purpose. Utilizing that process, part of the grape must from the depectinizing tanks 20 is drawn into a C02 pres~sure tank 24 via conduit 26 and control valve 28.
The resùltant C02 charged grape must is then remixed with the remainder of the grape must drawn from the depec-tinizing tanks 20 by conduit 30 by means of a junction conduit 32 controlled by a valve 34. The grape must th~n passes on to my flotation tank 36 by means of conduit 38 where the separation occurs and the insoluble colloids 35 are removed as explained in my prior patent. In order to optimize the results, a floculant agent such as gelatin may be added before the juice enters the flotation tank.
The flotation procedure thereupon separates the insoluble particles in the depectinized grape must from .

-8- ~L125i99 the ,ju~ce arld '~.lerehy achieves a clean, nif,h grade ju,ce, froe of mUCil oI~ the linde,lr2b]e mateIlal ~hich also carllies ~he undesirable micro--organisms.
After the separation process the cleaned juice is d~livered to the fermentation t~nks 40 by conduit 42 and pump 43 where rerrnen~at:i on i s carried out.
It ~s true, of course, that if cleaning methods are used which are less effective than my flotation process, the juice will not be as good a quality and more of the bacterial retardant S02 will be re~uired in the fermentation process. Nevertheless, I have shown a process which will make wine commercially and in market-able quality and quantity using a centrifuge to separate the grape must from the skins and seeds, and I have found that if proper care is taken with the depectinizing and cleaning of the juice, the use of S02 can be avoided altogether.
I will now describe my procedure for separating the skins from the seeds after they have been separated from the grape must and placing them in condition for commercial uses. As I have indicated before, the skins and seeds are received from the centrifuge in a prac-tically dry condition. By that I do not mean that they are totally dry, however. The skins and seeds have some degree of moisture, generally 5% to 10% moisture content by weight, and are intermingled but are not stuck to-gether. With an air blower 44, the seeds and skins can be separated by wind sifting. This is accomplished by feeding the seeds and skins into the air tunnel 45 3 powered by blower 44 with the conveyor 16. The skins, being lighter, will be carried further away by the air stream than the seeds. Therefore, the skins are collected at 46 just prior to discharge of the air stream through a filter 47, and the seeds are collected at 48 and de-livered to a seed storage 49. This separation can alsobe done by a screening process which screens the skins away from the seeds, but I prefer the process just de-scribed. To illustrate the effectiveness of this step of my process, a sample of the seeds and skins produced by the '!I~'etz' lisin~egrator during the San Martln ~Jinery experiment ~ere sepdrated using the Keller Sifter. There ~as no ~re-drying and the res~lt ~as an almost 100 separatiGn with ~0~ see~1s and 20~ skins by weight.
After separation has been achieved, the seeds can be crushed and the oil extracted from them. Gra~e seed oil can be compared in quality to olive oil. The skins, stems and crushed seeds can be composted and used as a mulch for organic gardening and for other purposes.
After the skins are separated from the seeds, extraction of the color and additional flavor from the skins of red grapes, and even white grapes if desired, can be economically accomplished. To achieve this I
use a mixer 50 in which the grape skins, after separation from the seeds as explained above, are deposited and intermixed with a 10% to 20~ sample of the wine from conduit 52, and with cellulase enzymes. The enzymes open the skin structure and the coloring compounds are then easily released. The wine sample will then absorb the red color and additional flavor from the skins and when separated from the skins by the rollers 54 and recombined with the rest of the wine batch via conduit 55, will transmit the red color and flavor from the skins to the entire batch. The skins pass from the rollers to a skin storage 56. Other methods may be explored to achieve the color and flavor extraction from the skins, however, I
do not recommend heatlng or the use of sulphur dioxide.
Conducting fermentation of the wine in the presence of the skins may be an equally effective means for extrac-3 tion of color and flavor.
Another aspect of my process is that at the endof the fermentation, the wine can be racked off, and the settled yeast and tartrates can then be separated from -each other by use of a machine such as the F R Dorr Clone, manufactured by Dorr-Oliver, Stamford, Connec-ticut. The yeast can then be spray dried and used for vitamin produc~ion, vegemeats, etc. Part of the re-covered yeast can be used by the winery for innoculation 11~5~39 of rresh juices to aid fermentatlon. The manner ~
accompllshing the recovery of yeast ls disclosed in my prior patent number 3,741,770.
From this descriptlon of a preferred embodiment of my process~ it will be understood that I can effec-tively utilize centrifugal separation of t'ne crushed grapes to provide a high yield of wine juice which can be depectlnized and cleaned to give a high quality wine.
At the same time, I can salvage the sklns and seeds, extract color and flavor from the skins for red wines, and make commercially usable materials from the by-products. It should thus be clear that my process is fully capable of providing the advantages and achieving the objectives hereto attributed to it.

Claims (10)

1. A process for the commercial manufacture of wine comprising the following steps: first, subjecting wine grapes to a destemmer and crusher; second, subjecting grapes from said crusher to a screening centrifuge to separate the grape must from the skins and seeds to such an extent that said skins and seeds are left almost entirely free of moisture; third, subjecting the grape must to a separation procedure for separating the in-soluble colloids from the grape must and for providing a juice suitable for fermenting; and fourth, fermenting the grape juice.

2. A process as claimed in Claim 1, wherein the third step includes: depectinizing the grape must; mixing at least a substantial portion of the depectinized must with a gas under a pressure of approximately 40 pounds per square inch, whereby a high proportion of the gas goes into solution; remixing the pressurized must with any remaining unpressurized must; subsequently separating clear juice from the solids of the must by flotation at atmospheric pressure whereby the gas is released from solution in the form of small bubbles which pass upwardly through the grape must to carry therewith substantially all of the insoluble solids; and removing the separated solids from the juice.

3. A process as claimed in Claim 1, further including the fifth step of separating the skins and seeds from one another.

4. A process as claimed in Claim 3, wherein said fifth step includes separating said skins and seeds from one another after they have been separated from the grape must by causing them to fall through a stream of blowing air whereby the skins, being lighter than the seeds, are carried further by the air stream than the seeds are carried.

5. A process as claimed in Claim 3, which fur-ther includes the step of drawing color from the skins after they are separated from the grape must and seeds by mixing at least a portion of the fermenting juice with the skins, extracting the liquid from said mixture, and remixing it with the remainder of the fermenting juice.

6. A process as claimed in Claim 1, which fur-ther includes the steps of: drawing off from 3% to 30%
of the wine batch after fermentation mixing said wine with cellulase enzymes, soaking skins from red grapes in said mixture until the color from said skins is substan-tially all incorporated into said mixture; drawing off the resultant colored mixture and pressing any of said mixture from said skins; and adding said mixture to the balance of said wine batch.

7. A process as claimed in Claim 1, wherein said screening centrifuge is disposed and operated to achieve a separation of skins and seeds having a moisture content by weight of less than 20%.

8. A process as claimed in Claim 1, wherein said screening centrifuge is operable to separate said grape must from said seeds and skins to the extent that said seeds and skins have a moisture content by weight not in excess of 10% after said separation.

9. A process as claimed in Claim 7, wherein said third step includes subjecting said grape must to a further centrifugal separation in a second screening centrifuge whereby larger particles and insoluble colloids are removed from said must to provide clean juice suitable for fermentation into wine.

10. A process as claimed in Claim 9, wherein said grape must is depectinized prior to said further centrifugal separation.