Group Title: Citrus Station mimeo report - Florida Citrus Experiment Station ; 60-6
Title: Citrus vinegar
Full Citation
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 Material Information
Title: Citrus vinegar
Series Title: Citrus Station mimeo report
Physical Description: 4 leaves : ; 28 cm.
Language: English
Creator: McNary, Robert R
Dougherty, Marshall H
Citrus Experiment Station (Lake Alfred, Fla.)
Florida Citrus Commission
Publisher: Florida Citrus Experiment Station :
Florida Citrus Commission
Place of Publication: Lake Alfred FL
Publication Date: 1959
Subject: Citrus fruit industry -- By-products -- Florida   ( lcsh )
Vinegar -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
non-fiction   ( marcgt )
Statement of Responsibility: R.R. McNary and M.H. Dougherty.
General Note: Caption title.
General Note: "September 16, 1959."
 Record Information
Bibliographic ID: UF00072397
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 74839499

Full Text

Citrus Station Mimeo Report 60-6
September 16, 1959

Citrus Vinegar
R. R. McNary and M. H. Dougherty

In this country, the traditional raw material for vinegar production has
been apple juice or cider. Cider vinegar is the standard by which other vinegars
are compared for flavor and cost. Within the last decade or two however, the
commercial production of wine vinegar has shown considerable growth. While the
volume is not great compared to cider vinegar, it is marketed at a considerably
higher price, exclusively for table use. In view of this, it was decided to
examine the possibility that citrus juices and by-product liquids could produce
vinegars of competitive quality and cost.

Vinegar making is a two step process in which sugars are first fermented to
alcohol by yeast. Acetic acid bacteria then convert the alcohol to acetic acid.
The yeast fermentation is essentially anerobic in nature while, on the other
hand, air is needed for the oxidation of the alcohol to acetic acid by the
bacteria in the secondary fermentation. The two steps therefore must be carried
out separately in different equipment. Extended intervals may occur between the
steps if necessary. The yeast fermentation may be carried out whenever the raw
material becomes available, with storage of the alcoholic liquor and conversion
to vinegar at a later date.

There are three main processes by which alcoholic liquor can be converted to
vinegar and which have been used to produce citrus vinegar. They differ in speed
of conversion, which is directly related to the rate that oxygen can be absorbed
from the air and utilized by the bacteria, and in efficiency of conversion.

The Orleans Process. This process is referred to as the slow process and
is carried out in shallow vessels having screened openings at the top to admit
air and exclude insects. The acetification takes place in a film of vinegar
bacteria which grows on the surface of the liquid in contact with the air. The
speed of conversion of alcohol to acetic acid is slow and the efficiency of con-
version is somewhat less than the other processes but the quality of the product
is very good. Since it requires little attention, this process is favored when
a number of small batches of vinegar are to be made.

The Generator Process. This process increases the rate of acetification by
increasing the contact area between the alcoholic liquor, the bacteria, and the
oxygen in the air. This is done by trickling the alcoholic liquor down through
a column packed with beechwood shavings to which the acetic acid bacteria have
become attached. The fermentation generates heat causing a continuous updraft of
air through the column which supplies the oxygen necessary to the growth of the
culture. The conversion of alcohol to acetic acid is slightly more efficient
than in the Orleans process.

The Submerged Fermentation Process. This process differs from the other two
in that the bacteria are uniformly distributed throughout the liquid being aceti-
fied. Oxygen is supplied by dispersing air in fine bubbles throughout the liquid.

Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida.
936 9/16/59 RRMc

Vigorous agitation accompanies and is necessary to the dispersion. The process
was first developed in Europe but has been perfected to the highest level in this
country in the past three years (1). The conversion of alcohol to acetic acid in
this process is more complete with as high as 98 per cent conversion being
achieved in a properly operated fermenter. This compares with 80 to 88 per cent
in the generator process and 70 to 80 per cent in the slow process.

The first vinegar produced in this laboratory was made with a small, labora-
tory-scale generator. The original culture of acetic acid bacteria was obtained
as an unpasteurized and unfiltered sample of vinegar from a commercial vinegar
manufacturer. The generator was kept in continuous operation for 29 months making
vinegar from orange, grapefruit, tangerine and citrus molasses wines. Most of
these vinegars were of good or excellent quality and considered worthy of further

The generator used had the disadvantage of having a very small capacity and
most of the product was used to obtain analytical data. To enlarge the quantity
and to investigate a large number of variables simultaneously, the slow or Orleans
process was resorted to. The use of this process had the advantage that the
batches could be kept small with a number of batches in progress at the same time.

The Orleans process was also used to produce small batches of vinegar from
fruit that had been badly frozen during the cold weather of December 1957 and
January 1958. The vinegar produced from this frozen fruit was found to be as
good in all respects as that from otherwise sound fruit.

While both the Orleans and packed generator processes have served very use-
ful purposes in the development of quality vinegars from citrus fruits, the only
process that need be considered for commercial production at the present time is
the submerged fermentation. The fermenter used in the submerged fermentation ex-
periments was a pilot plant model "Cavitator'l1 consisting of a 20 gallon trans-
parent plastic tank with vertical baffles to stop vortex action. A helical coil
of stainless steel tubing inside the tank carried cooling water for temperature
control. The rotor with its hollow shaft and the draft tube was made of stainless
steel and was attached to the stainless steel lid. Spinning of the rotor caused
air to be sucked down the hollow shaft and become dispersed in fine bubbles in
the liquid. Practically instantaneous mixing of the liquid was also produced by
the rotor action. Power for driving the rotor was supplied by a 1/4 hp., U.S.
Varidrive motor. A Sigmamotor pump, with attached speed changer and motor, was
used to meter the wine feed from the supply tank to the Cavitator. Tygon tubing
was used to transport both wine and vinegar between different pieces of equipment.
Feed and product tanks consisted of open-end, 55 gallon, steel drums with plastic
liners made of polyvinylchloride. Cheesecloth was draped over the open ends to
keep out insects and plywood covers prevented appreciable evaporation.

Approximately 550 gallons of different kinds of citrus vinegars were produced
by submerged fermentation. The types were orange, tangerine, grapefruit and orange
peel vinegars. With the exception of one batch of orange vinegar, all of the pro-
ducts were made from raw materials that had been partially concentrated prior to

1 Trade name registered by Yeomans Brothers Company.

Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida.
936 a 9/16/59 RRMc

the alcoholic fermentation. This was necessary to bring the concentration of
fermentable sugars in the juices up to the level where enough alcohol would be
produced to give a 60 grain (6% total acidity) vinegar. Only one batch of orange
juice used was fortified by adding sugar until the desired degree Brix was obtained.
It was noticed that the vinegar prepared from this had appreciably less character-
istic flavor than that made from partially concentrated raw materials.

Peel oil present in small amounts in citrus juices have been found to be
responsible for a "terpeney" or "furniture polish" off-flavor which develops in
citrus wines when they are allowed to stand at room temperatures for an extended
period of time. This off-flavor, if allowed to develop, will carry over into the
vinegar. The removal of much of this oil before the alcoholic fermentation is, in
the case of the fruit juices, accomplished when the material is partially concen-
trated. The remainder can be eliminated by filtration immediately after the
alcoholic fermentation is completed. In the case of peel liquor, it was found
that complete removal of suspended solids was necessary prior to partial concen-
tration of the liquor. The concentrated peel liquor was only then found to be low
enough in peel oil so that no off-flavor developed.

A criterion of good vinegar is clarity of the final product. Turbidity or
cloud is desirable in citrus juices but when these juices are converted into
citrus vinegars the removal of the turbidity becomes a problem. The pectic sub-
stances in the juice cause a sliminess which inhibits to a great degree the fil-
tration of the wine. To overcome this problem, pectic enzymes were employed to
destroy these substances. The addition of enzymes created another problem of
sediment formation in the final product. However, after screening a number of
different enzymes, one was found that did not cause sedimentation. The enzymes
were added to the juices just prior to the yeast fermentation and the enzymatic
reaction and fermentation were carried out simultaneously. The quantity of enzymes
used ranged from 0.01 to 0.02 per cent by weight.

Vinegar making is traditionally a competitive business based upon large volume
and low profit margins. Production of wine vinegar is a possible exception since
it is relatively new and the volume is not great. Orange vinegar has the least
chance of successfully competing with the established products unless the juice
can be obtained at distress prices. Grapefruit and tangerine vinegars have in-
teresting possibilities since it is likely that their juices can be obtained at
low cost at certain times of the year. Citrus peel vinegar has great potentiali-
ties as far as costs are concerned but remains to be tested for public acceptance.

It would be wise for anyone planning to enter into the manufacture of citrus
vinegars to become familiar with the federal regulations before proceeding with
construction or allotment of manufacturing space in order to avoid violations.
Part 240, of Title 26 (1954), Code of Federal Regulations, entitled "Wine", covers
the qualification of bonded wine cellars. Part 195, of Title 26 (1954), Code of
Federal Regulations, entitled "Production of Vinegar by the Vaporizing Process",
should also be consulted.

Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida.
936 b 9/16/59 RRMc



It is the opinion of many that the quality of citrus juice vinegars is such
that they should have a place in the vinegar industry. Just where the niche may
be can only be determined by marketing trials. It is believed that they compare
favorably with wine vinegars now being marketed, but only the public can confirm
this. Until better cost figures are available, it is not expected that citrus
juice vinegars may be produced as cheaply as cider vinegar. On the other hand,
citrus peel vinegar should be a low cost item. Whether its flavor will be accept-
able as a table vinegar or whether it would be useful in prepared foods, such as
sauces and dressings, remains to be seen.


1. Cohee, R. F. and Grover Steffen. Makes vinegar continuously.
Engineering, 31, 3, 58-59 (1959).


Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida.
936 c 9/16/59 RRMe

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