Published October 1902. Facts and recommendations in this publication may no longer be valid. Please look for up-to-date information in the OSU Extension Catalog: http://extension.oregonstate.edu/catalo

Oregon Agricultural College. Experiment Station

Pernot, E. F. (Emile Francis), 1859

Undetermined

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II5000.Bulletin No. 73. October, 1902.DEPARTMENT OF BACTERIOLOGY.OREGON AGRICULTURAL EXPERIMENT STATION,CORVALLIS, OREGON.Notes on Vinegar Making.L3 E.. F. PERNOT.Th u1ett of this taioyi are Sent Fre'e to all esidettSOregon who reQuest them.kGreULTtRAL OLLEUE PRIITNG OFFIGEO. fl. EADV, PRINTEF.1902.Board of Regeots of the OregoD AgrcuIturaF Colege ad Eerimeot Station1Hon. J. K. Weatherford, President Albany, Oregon.Hon. John D. Daly, Secretary Corvallis, Oregon.Hon. B. F. Irvine, Treasurer Corvallis, Oregon.Hon. T. T. Geer, Governor Salem, Oregon.Hon. F. I. Dunhar, Secretary of S/ate Salem, Oregon.Hon. J. H. Ackerman, Stale Suj5t. of Pub. Instruction, Salem, Oregon.Hon. B. G. Leedy, Master of Stale Grange Tigardville, Oregon.Hon. Benton Killin Portland, Oregon.Hon. Jonas M. Church La Grande, Oregon.Hon. William E. Yates Corvallis, Oregon.Hon. J. T. Olwell Central Point, Oregon.Hon. J. T. Apperson, Park Place, Oregon.Hon. W. P. Keady Portland, Oregon.OFFICERS OF THE STATION.STATION COUNCIL.Thos. M. Gatch, A. M., Ph. D Presuieni.James Withycombe, M. Agr.. Diredoe' and Ag-ricullurisE.A. L. Koisely, M. S. OzemisLA. B. Cordley, M. S .. .En/omo/ogisLK. R. Lake, M. S HorIicullarj.,I and Bolanisi.F. Pernot Bacteriology.Other Members of St&ff.George Coote Florist.L. Kent B. S Dairying.C. M. McKellips. Pb. C., M. S Chemistry.F. E. Edwards, B. M. K. - - Chemistry.NOTES ON VINEGAR MAKING.As the prune industry in this state develops, growers realize thatthere is an increased amount of prunes, which through manycauses, become unfit for drying purposes, prunes which are overripe, and those bursted open, under sized prunes, and unsaleableones, all go to make up a large product which is annually wasted.The utilization of waste products goes far towards defraying the ex-penses of raising the crop. WTith this in view, an experiment wasbegun September 25th, 1901, in making vinegar from the wasteprunes which were rejected for drying at the experiment station.No prunes were used that were in any way decomposed. The firstproblem that arose, was, how to extract the clear liquid, the prunesbeing of such peculiar structure that the juice could not be extract-ed by pressure, without being thick and turbid. In order to over-come this difficulty a vat was constructed of the following dimen-sions, which answered the purpose admirably, although it was toolarge for the amount.of prunes available.The foundation of the vat consisted of cross pieces 3 feet 10 incheslong varying in heighth from 8 in. to 13 inches which gave an in-cline to the tank bottom, to these cross pieces fir flooring was toenailed and the joints were painted with thick white lead, the sur-face was painted and a second floor laid on top in a similar manner,making a double floor, water tight, 13 ft. 2 in. long, 3 ft. 10 in.wide.Near the edge of this floor, a strip 1x2 inches was leaded and nailedall around except at the lower end, where two strips were naileddiagonally so as to form a spout. A second strip 2x4 was fastenedto the floor two inches inside of the outer one, so as to form a gutterbetween the two, instead of nailing it tight to the floor it was pro-vided with thin cross strips at intervals of about eight inches so asto allow the liquid to pass into the gutter. On the inner side ofthis strip, flooring four feet long was toe-nailed in an upright position, but before nailing, a strip of burlap about two inches wide wasplaced between the ends of the boards and tank bottom so as toform a filter. Midway up and at the top, the sides were toe-nailedto frames of 2x4 material, thus forming a strong tank free fromobstructions inside. No nails were allowed to be exposed nor tocome in contact with the prunes or juice.On the top of the vat, a large hopper was constructed provided4at its lower end with a large wooden roller in which were drivennails projecting about three-fourths of an inch from its surface, acrank was fastened to the end of the roller and allowed to extendacross the outside of the vat.The prunes, after being washed and weighed, were put into thehopper, and by turning the crank they were torn and passed to thevat below. After several bushels of prunes had accumulated in thevat, they were inoculated with a pure culture of yeast sacckaromyce.ccerevisia, which caused a strong and rapid fermentation, the cellwalls of the prunes were thus broken down, liberating the clearjuice, which poured into the receptacle below the vat. The objectof lacerating the prunes with the spiked roller, was to allow theerment to more readily destroy the cell walls. This method of ex-tracting the prune juice was inexpensive and perfectly satisfactory.In this experiment 10,482 pounds of Italian prunes was used, fromwhich 830 gallons of juice was obtained, a yield of over threegallons per bushel3 greatly exceeding expectations.As the prune juice was collected, it was emptied into open barrelsand there allowed to remain undisturbed for ten days, when fer-mentation ceased. An analysis at that time showed ten per centalcohol.After the liquid in all the barrels had ceased fermenting, a pureculture of acetic acid germs, bacilli Pasleuranurn, which had previ-ously been prepared in the laboratory, was floated on the surface ofthe liquid by the aid of thin pieces of cork, weighted, so as to bringthe culture in contact with the liquid, in course of time a delicatescum spread over the entire surface of the liquid and the formationof acetic acid began. Every month the material was tested foracetic acid and was found to vary considerably although the barrelswere kept under similar conditions, the highest test at the presenttime is 3.43 per cent acid.At the same time that the prune juice was placed in the barrels,several half-gallon jars were filled and kept in the laboratory; onear in which the liquid has evaporated to a considerable extenttests as high as 8.59 per cent acid, and another one tests 6.73 percent; this was due to the volume of material being smaller than inthe barrel, and the temperature higher. The barrels were left in thedryer until the latter part of October, when it was found that theformation of acetic acid had almost ceased, owing to the low tern-perature,. they were then moved to the cellar of the horticultural0building where a warmer atmosphere prevailed. The progress ofvinegar making was thus very much impaired by the liquid havingbeen disturbed; as the barrels had no heads, it was necessary touse the svphon in conveying it from the barrels above ground tothose in the cellar, consequently the cultures which had formed ascum on the surface, were destroyed, necessitating a reinoculationto form a new scum. The vinegar is of an excellent quality, possess-ing a fruity flavor, it has a good body, analyzing 6.87 per cent totalsolids, and the only objection that can be raised is to the color,which is that of very dark wine.There can be but little objection to its color however, since it isbut little, if any, darker than the imported malt vinegar whichfinds ready sale in our markets, and it is probable that some waywill yet be found to clarify it and reduce the color. Experimentsare now in progress for making vinegar from Petite prunes, andfrom Italian prunes from which the skins were removed, to see ifthe dark color could be obviated. A new vat was constructed onthe prineiple of the old fashioned ash leech and it is found to workvery satisfactorily.It is perhaps not out of place here to give a brief description ofthe formation of vinegar (acetic acid) from fruit juices.To obtain the best results, or highest per cent of acetic acid fromfruit, it should be fully ripened so as to contain the maximumamount of saccharine matter, this is first acted upon by ferments,which find it a suitable material to grow in, and in so doing thesugar is consumed, being split up into other elements, the principalone being alcohol, carbonic acid gas being liberated at the sametime, passes away, leaving a liquid composed of water, alcohol, or-ganic and mineral solids; the amount of alcohol varying accordingto the amount of saccharine matter in the fruit juice. After the al-coholic fermentation takes place, other organisms find the materialconducive to their development, and begin their activities. Theyconsume alcohol, converting it into acetic acid. It is absolutelynecessary that these organisms have unobstructed access to all theair that they desire, or oxidization through their activities will beimpaired. Therefore a barrel filled with fruit juice and bungedcan not form vinegar as rapidly as one half filled, and with thebung taken out.It is the habit of many people to fill a barrel with cider whichthey intend for vinegar, and in place of the hung, to insert an empty6quart bottle in the bunghole. This is not only useless, but detri-mental as it excludes the organisms necessary to form vinegar andshuts out the air which is requisite for those which may alreadyhappen to be in the liquid.There is a small yellow fly, Drasophila amj5e1oIzila, commonlyknown as pomace fly, vinegar fly, and drunkards, which frequentthe vicinity of vinegar barrels and decomposing fruit. They are in-strumental in carrying from place to place the acetic acid germsand ferments, doing more good than harm to material which is in-tended for vinegar. This was demonstrated in the laboratory inthe following manner: Some of these small flies were caught by thewings with sterile forceps while they were at work on the open bar-rels of prune juice, they were conveyed to the laboratory and liber-ated under the cover of shallow dishes which contained sterile cul-ture media, and there allowed to remain long enough to walkseveral times across the surface of the material, and then liberated;the dishes were then placed in an incubator for twenty-four hours,after which time there was a visible growth of acetic acid germswhere their feet had touched the media. The bodies of these flieswere then taken and crushed between a microscope slide and coverglass, and examined under a high power microscope; it was foundthat the digestive tract contained an immense number of acetic acidgerms, and yeast plants, which the fly had taken up with its food.In order to determine whether the organisms had lost their vitalityin passing through the digestive organs of the fly, several flasks offresh cidar were sterilized, the flasks were provided with the usualcotton plug, with the exception of having a small glass tube pass-ing through the center, which was also plugged with cotton at itsouter end. When all were perfectly sterile, flies were caught underaseptic precautions, and one fly dropped into the liquid of eachflask through the small tube, the plugs were replaced and the flasksplaced in the incubator, after remaining there for forty-eight hours,a fermentation had taken place and they were removed to the tem-perature of the laboratory. After eight months the flasks wereopened and the material tested for acetic acid, one flask testing ashigh as 3.29 per cent acid, a fairly good vinegar, the other flaskswere of a lower percentage. A check flask was prepared in thesame manner as the others, with the exception of not being inocu-lated with a fly and being kept under the same condition,, it re-mained sterilerhile it appears that the pomace fly renders a valuable servicein inoculating fruit juices with the necessary germs for producingvinegar, they are also apt to carry spores of moulds and other or-ganisms, which impart a bad odor or taste to the finished product.Therefore instead of relying upon accidental inoculations, vine-gar of standard taste may be produced by using cultures of selectedferments, in the same manner as the flavor of wine and beer is con-trolled by the manufacturer. In the bacteriological laboratory ofthis station, pure cultures of the acetic acid ferments are constantlykept on hand, and will be furnished to anyone in this state uponapplication.Most of the pure fruit-juice vinegars, contain ang-nilla ace/i,commonly known as vinegar eels, which are large enough to beseen with the naked eye, and resemble eels both in form and move-ment. They are a detriment to the vinegar inasmuch as theyconsume the material, and at death sink to the bottom of the re-ceptacle, where, if they decompose, unpleasant odors and tastes areimparted to the product in consequence. It is difficult to preventtheir entering the material and still more difficult to remove themwhen established.Fruit juices, especially apple cider, contain a certain amount ofalbuniinous matter, which, as the acetic acid fermation increases,becomes coagulated, forming a scum which gradually thickens as itbecomes older, if one surface of this is exposed to the air, it driesand becomes a leathery mass familiarly termed, "mother of vine-gar," it contains an immense number of the acetic acid germs, andis useful in inoculating fresh material which is to be converted intovinegar.The process of making vinegar for home use, or even for market,is simple and quite within reach of everyone, the first requisite is tohave perfectly clean barrels or vats. This may be accomplishedby thoroughly scalding several times with boiling water or livesteam, so as to destroy the spores of moulds which may he present.Well ripened fruit should be used, because it contains a greateramount of sugar, and will yield a higher per cent of acetic acid.Fruit that is decomposed, should not be used. After the juiceshave been obtained and emptied into the receptacles, dissolve ayeast cake in a small amount of liquid, pour it into the mass andthoroughly stir with a clean stick, a strong fermentation will soontake place which should be allowed to continue undisturbed until8it ceases of its own accord, then procure some "mother of vinegar"from a sample which suits the taste, or a pure culture of acetic acidgerms, and float it upon the surface of the liquid by means of a fewclean straws, and leave undisturbed in a warm place. A delicatescum, which must not be broken, will soon form on the surface ofthe liquid. The rapidity of the transformation to vinegar will de-pend upon the temperature at which the material is kep. A tem-perature of 80 degrees F. will give the most rapid results.Apple vinegar has been made in this manner at the station,which, in four months, yielded a delicious tasting article, that testedsix per cent acetic acid, and five gallons of vinegar from pearsmade last year, in five months, tested 8.89 per cent acetic acid.This was strong enough to be diluted one half with water, and stillbe stronger than the law of this state requires, which is four percent. To recapitulate--there are several conditions to be con-sidered in making vinegar in this way. The barrels must be freefrom must and mould, the depth of the liquid should not exceedthe surface measure, free air must be continually admitted, an even,warm temperature should be maintained and, last but not least,the fruit that is used should be free from decay and mouldThere is no reason why all the fruit which annually goes towaste in this state, cannot be made into good, wholesome vinegarfor our home consumption and for export trade, instead of import-ing an unwholesome article, made from distillery refuse, whichfloods our markets. Not only would it become a source of income,but it would remove from our orchards material which decays andbecomes an asylum for insect pests and fungus diseases.There are other methods of making vinegar from fruit juices, i. e.with generators, which are much more rapid in their action. Theprinciple is simply to expose to the air broad surfaces of liquid toincrease the action of oxidization through the activities of aceticacid ferments. Any device so constructed, as to allow a smallstream of inoculated cider to flow slowly over a series of inclinedsurfaces, in the presence of warm air, will form acetic acid muchmore rapidly than if the same material were placed in deep vats orbarrels, because the organisms which are instrumental in the con-version of acetic acid, require an abundance of oxygen. Beechshavings are sometimes used, because their many surfaces in theaggregate present a large area and no bad taste is imparted to thevinegar from that wood.

Notes on vinegar making

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Notes on vinegar making

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