Purification of beverages

A method of removing haze precursors from wine vinegar and other beverages by passing it through a bed of an ion-exchange resin material in hydrogen form. The resulting clarified wine vinegar is then matured. The resin material is regenerated in situ by sulphuric acid.

This invention relates to the purification of beverages and more 
particularly to the clarification of beverages, e.g. wine vinegar, malt 
vinegar and light beer, by the removal of haze-promoting precursors. In 
this specification the term "wine" means grape wine. 
Haze precursors are soluble substances found in alcohol-based beverages 
which form precipitates with ageing or with chilling and thereby produce a 
haze or cloudiness which may be objectionable for clear vinegar or larger 
beer. 
In the production of wine vinegar, after acetification it is common 
practice to mature the raw vinegar for some time in a succession of large 
wooden vats. To remove haze precursors and thus ensure a clear vinegar the 
lower portions of the vats are filled with beechwood in slab or chip form. 
The beechwood has been pre-treated by soaking it in a strong vinegar to 
enable it to carry out better its clarifying function of removal of haze 
precursors from the vinegar maturing in the vats. The raw vinegar is 
passed through the beechwood in successive vats to emerge from the last 
vat having a visual clarity. 
During such maturation of the raw vinegar the beechwood loses its 
efficiency as a clarifier, partly because it becomes coated with 
impurities from the vinegar and partly because, it is thought, its 
inherent capability to remove haze precursors from the vinegar is 
adversely affected. Accordingly, it is necessary to clean and regenerate 
the beechwood. This may be carried out by removing the beechwood from each 
vat in turn,, washing it with water in a tumble drum and then returning it 
to the vat. This treatment requires each vat to be taken out of service 
for about a week. In addition the interior of each vat has to be cleaned 
whilst it is out of service. 
The present invention avoids the traditional requirement for large 
maturation vats provided with beechwood for purification. It also provides 
a clarifying agent which is more quickly regenerated than beechwood and 
furthermore may be regenerated in situ. 
According to the invention, a method of removing haze precursors from a 
beverage, e.g. wine vinegar, malt vinegar or light beer, comprises 
contacting the beverage with an ion-exchange resin material in hydrogen 
form to remove at least nearly all haze precursors. 
The resin material may be a gelular, strongly acidic, cation exchange resin 
of the styrene-di-vinyl-benzene type which has been regenerated in 
hydrogen form by sulphuric acid.

By way of example the invention will now be described with reference to the 
following examples: 
EXAMPLE I 
Raw Vinegar made from Wine 
After acetification in a known manner the now alcohol-free wine vinegar is 
passed through a filter to remove any solids and then passed downwards 
under gravity through a small tower containing a column or bed of discrete 
ion-exchange resin material in hydrogen form to remove all, or nearly all, 
the haze precursors from the raw vinegar. Thereafter the vinegar is 
matured in a series of maturation vessels which do not contain any 
beechwood or other haze precursors removing agent and therefore can be 
designed solely for maturation. 
The ion-exchange resin material is preferably a gelular, strongly acidic, 
cation exchange resin of the styrene-di-vinyl-benzene type which has been 
regenerated in hydrogen form by sulphuric acid. An example of such a 
material is marketed in bead form under the trade reference AMBERLITE 
IR-120 by Rohm and Hass (UK) Limited of Croydon, Surrey. 
The filtered raw vinegar is passed through the bed of AMBERLITE IR-120 at a 
rate in excess of 2 gallons of vinegar per cubic foot of resin material 
per minute and at room temperature. The subsequently matured vinegar is 
clear and potable and remains so after over ten months. 
The resin material in its own clarification tower has a further advantage 
over the traditional beechwood in the maturation vats, viz. it can be 
easily and quickly cleaned and regenerated in situ in a matter of hours by 
backwashing with distilled water and then passing through it 5 lbs of 
66.degree. BAUME sulphuric acid per cubic foot or resin material at about 
0.5 gallons per cubic foot per minute. 
Thus the bed of resin material in the tower is regenerated without 
interference with the subsequent maturation stage. As a result of 
transferring from the maturation stage the function of removal of all, or 
nearly all, the haze precursors, the maturation is speeded up. 
Another suitable resin material for the bed is ZEROLIT 225 which is 
referred to in Example II. 
EXAMPLE II 
Raw Vinegar made from Malted Barley 
Preparation of Bed 
A tower is filled with a column of an ion-exchange resin material in bead 
form which is a gelular strongly acidic cation exchange resin of the 
styrene-di-vinyl-benzene type. An example of such a material is that 
marketed under trade reference ZEROLIT 225 by Zerolit Limited of 
Isleworth, Middlesex. Sulphuric acid (4% W/V) is added to the column and 
thoroughly mixed with it, the resin beads being arranged to settle and 
form an air-free bed. One and a half bed volumes of further sulphuric acid 
(4% W/V) are run through the bed and then the latter is left overnight in 
sulphuric acid (4% W/V). The bed is then washed with distilled water until 
the effluent shows a pH of 4-5. The resin bed is now in the required 
hydrogen form. 
Treatment 
The raw malt vinegar is filtered to remove suspended particles present 
until it has a haze of less than 30 Helm Units as measured by a radiometer 
haze meter. The filter may be a Type 952 METAFILTER as marketed by 
Stella-Meta Filters Limited of Whitchurch, Hampshire. The filtered vinegar 
is then passed through the column or bed of ZEROLIT 225 at a rate of about 
six bed volumes per hour. The initial vinegar percolate leaving the bed is 
discarded because of dilution with the distilled water which remained in 
the bed. When however the vinegar percolate reaches the correct acidity, 
it is collected and then pasteurized at 80.degree. C. Maturing is not then 
required. 
Regeneration of Bed 
After treatment has finished, the resin bed is thoroughly washed with 
distilled water. One and a half bed volumes of sulphuric acid (4% W/V) are 
then passed through the resin bed and the latter is left overnight with 
this acid. After subsequent removal of the acid the resin bed is re-washed 
with distilled water until the effluent therefrom reaches a pH of 4-5. 
Thus regenerated, the bed is again in the required hydrogen form and ready 
to receive the next batch of filtered malt vinegar. 
Results 
Samples of the treated malt vinegar, both aerobic and anaerobic, together 
with untreated control samples were stored in bottles either in a warm 
room to speed up the process or in stores at ambient temperature and then 
regularly checked for haze using a radiometer haze meter calibrated in 
Helm Units. 
After a few weeks the control samples started to form a flocculant 
precipitate which aggregated and dropped to the bottom of the bottles thus 
giving false readings. The bottles therefore had to be shaken to bring all 
the precipitation into suspension to obtain a true haze reading. The 
results appear in the TABLE below, the figures in parenthesis representing 
the above-mentioned false readings. T refers to the treated samples whilst 
C refers to the control samples. 
__________________________________________________________________________ 
WARM ROOM AMBIENT STORES 
AEROBIC ANAEROBIC 
AEROBIC ANAEROBIC 
WEEK NO. 
T C T C T C T C 
__________________________________________________________________________ 
0 26 26 26 26 26 26 26 26 
4 36 146 36 102 26 97 29 94 
9 57 (89) 257 
50 (72) 221 
52 180 48 171 
12 78 (85) 444 
72 (46) 321 
78 (84) 350 
71 (73) 241 
17 97 (75)&gt;500 
76 (40) 335 
87 (83) 418 
72 (58) 255 
20 113 (89)&gt;500 
88 (70) 420 
115 (89) 496 
81 (53) 295 
27 122 (59)&gt;500 
87 (33) 410 
110 (63)&gt;500 
84 (37) 285 
45 280 (106)&gt;500 
104 (31)&gt;500 
160 (79)&gt;500 
95 (35) 349 
__________________________________________________________________________ 
The TABLE shows that the haze formation of the samples treated according to 
the invention is considerably less than that of the control samples. After 
45 weeks the anaerobic treated samples in the ambient stores which 
correspond to the bottled vinegar in the shops had no appreciable haze, 
i.e. they were acceptably bright. 
EXAMPLE III 
Finished Vinegar made from Malted Barley 
The treatment for finished malt vinegar is the same as that described for 
raw malt vinegar in Example II except that the initial filtering stage is 
not necessary and may be omitted. 
EXAMPLE IV 
Raw Light Beer 
The raw or unmatured beer is filtered to remove suspended particles and 
then passed down through a column or bed of AMBERLITE IR-120 resin 
material to remove all, or nearly all haze precursors. The resulting 
percolate when at the correct acidity is collected and then matured or 
finished.