Note: Descriptions are shown in the official language in which they were submitted.
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Method of Sterilizing Packing Materials
for the Aseptic Packaging
of Fruit Juice and Wine
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The invention relates to a method of sterilizing packing materials
for the aseptic packaging of fruit juice and wine using sulfurous
acid.
Bacterial spores do not develop in fruit juices and wines due to
unsuitable conditions for their growth. It it therefore unnecessary
to use, for the septic packaging of wine, the hydrogen peroxide
customary for sterilizing the packaging material, i.e. bottles, bags
and containers made of plastic or plastic-coated paper, used for
other drinks, such as milk. This could be substituted by sulfurous
acid which has already been used to combat the growth of fungi,
e.g. during the fermentation and bottling of wines. The effect of
sulfurous acid in killing bacteria is, however, too slight to achieve
sterility in the short time of a few seconds required by production
techniques.
The object underlying the invention is to provide a method of
sterilizing packing materials for -the aseptic packaging of fruit
juice and wincing sulfurous acid which satisfactorily kills germs
in a short time.
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This object is accomplished in accordance with the invention in that
the packing material is treated with aqueous solutions of sulfurous
acid and alcohol, preferably a lower aliphat:Lc alcohol containJ.n~
containing from 1 - 5 carbon atoms, such as 2-propanol, 1-
buttonhole, buttonhole, namely alcohol or ethanol.
It has been surprisingly found that a mixture of this kind acts
synergistically and has a microbicidal effect for the packaging of
beverages in question and this effect considerably exceeds that of
sulfurous acid without the addition of alcohol.
The hollowing specification serves to explain the invention in more
detail in conjunction with two Tables and a number ox drawings.
The attached drawings show diagrams Indicative of the effective-
news in killing germs (reducing -the number of germs as a function
of time) of sulfurous acid and alcohol on their own as well as
of mixtures consisting of sulfurous acid and alcohols, when used
for various yeasts, fungi and bacteria. The individual figures of
the drawings show, respectively:
Figure 1 - Killing S. cerevisiae with Nazi a-t pi 3.0 and
22C as a function of the concentration;
Figure 2 - Killing Saccharomyces~cerevi~iae with Nazi
(10,000 Pam, pi 3) as a function of the temperature;
Figure 3 - Synergistic effect of Nazi (10,000 ppm/pH 3.0) and
alcohol 15% when killing S. cerevisiae (-temperature 22C);
Figure 4 - Killing A. Niger with Nazi at pi 3 as a Junction
of the concentration and the temperature;
Figure 5 - Killing A. Niger with Nazi (10,000 Pam, phi) and
alcohol (15~) at 22C.
Figure 6 - Killing Mocker with Nazi, pi 3.0 at 22C as a
function of the concentration;
Figure 7 - Killing Mocker with Nazi (10,000 Pam, pi 3.0) as
a function of -the temperature;
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Figure 8 - Killing Mocker with Nazi (10,000 Pam, pi 33 and
Ethanol (10%) at 22C;
Figure 9 - Killing Mocker with Nazi (10,000 ppmr pi 3) and
Ethanol (10%) at 50C;
Figure 10 - Killing Gluconobacter with Nazi (pi 3) at 22C
as a function of the concentration;
Figure 11 - Killing Gluconobacter with Nazi (10,000 Pam and
40,000 Pam, pi 3) as a function of the temperature;
Figure 12 - Killing Acetobacters (Gluconobacter) with Nazi
(30,000 Pam, pi 3.0) and Alcohol (30%) at 22C.
Figure 13 - Killing Acetobacters ~Gluconobacter) with Nazi
(20,000 ppml pi 3) and Alcohol (15%) at 50C;
Figure 14 - Killing Acetobacters (A. acetic with Nazi
~0,000 Pam, pi 3) and Alcohol (15%) at 50C;
Figure 15 - Killing Leuconostoc dextranicum with Nazi (10,000
ppm/pH 3) as a function of the temperature;
Figure 16 - Killing Leuconostoc dex-tranicum with Nazi t20,000
Pam, pi 3) and Ethanol (15~) at 22C;
Figure 17 - Synergistic effect of Nazi (10,000 ppm/pH 3) and
l-Propanol (10%) at 22C for killing Yeasts (Saccharomyces
cerevisiae);
Figure 18 - Synergistic effect of Nazi (10,000 ppm/pH 3) and
2-Propanol (10%, 20%) at 22C for killing Yeasts (Saccharomyces
cerevisiae~;
Figure 19 - Synergistic effect of Nazi (10,000 ppm/pH 3)
and l-Butanol (0.5 - 5%) at 22C-for killing Yeasts (Saccharomyces
cerevisiae)
Figure 20 - Synergistic effect of Nazi (10,000 ppm~pH 3.0
and buttonhole (5%) at 22C for killing S. cerevisiae;
Figure 21 - Killing S. cerevisiae Synergistic effect of Nazi
(10,000 ppm/pH 3) and namely alcohol I at 22C;
Figure 22 - Killing Mocker. Synergistic effect of Nazi
(10,000 Pam) and 1 Propanol (15~) at 22C;
Figure 23 - Killing ~cetobacters (Gluconobacter) Synergistic
effect of Nazi (10,000 ppm/pH 3.0) and l~Propanol (15%) at 22C
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Figure 24 - Killing Lactic Acid Bacteria (L. dextranicum)
Synergistic effect of Nazi (20,000 ppm/pH 3.0) and l-Propanol
(10%) at 22C.
The following microorganisms were used during the course of tests
carried out in conjunction with the invention to examine the
microbicidal effect of sulfurous acid on its own and sulfurous acid
combined with alcohol:
Yeasts (Saccharomyces cerevisiae)
Molds (Aspergillus Niger and lucre)
Acetobacters (Acetobacter acetic and Gluconobacter)
Lactic acid bacteria (Leuconostoc dextranicum)
The test substances were aqueous mixtures (solutions) owe sodium
disulfite [pyrosul~iteJ (Nazi) and ethanol, the ethanol being
present in a concentration of between 96 and 100%. Sulfurous
acid it most
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effective in killing germs in a very acid state. The sodium
disulfite is therefore, after it has been dissolved in water,
acidified with citric acid to a pi of 3Ø The mixed alcohol-
containing Nazi solution which has now been acidified contains,
apart from alcohol, sulfurous acid in various stages of dissociation
the sulfurous acid being the most effective aseptic substance.
The effectiveness of the substances in killing germs was tested as
a function of their concentration at varying temperatures.
Fig. 1 shows the time curve for killing Saccharomyces cerevisiae at
22C and at various concentrations of H2S03 (added in the form of
Nazi). Killing is quickest at a concentration of 40,000 Pam. A
D value of Do = 2 seconds is hereby reached. (The D value specifies
the time in which a predetermined germ count is reduced by one
decimal power at a redetermined temperature).
Fig. 2 illustrates the killing of the yeast S. cervisiae as a function
of the temperature. Then the concentration of assay remains at
10,000 Pam, the greatest number of germs are killed at 50C. The
decimal reduction time is again approximately 2 seconds (D50 - 2
seconds).
Lye effectiveness of sulfurous acid in killing germs is precipitously
intensified when alcohol (ethanol) is added, as shown in Fig. 3. When
sulfurous acid is used alone (10,000 Pam, 22C), a D value of
D22 = 37 seconds results in the case of S. cerevisiae but this may
be considerably accelerated by adding ethanol (15 % by weight). The
D value is then only approximately 2 seconds. As also shown in
Fig. 3, of. the top curve, ethanol on its own has practically no
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germ-killing effect The synergistic effect of the mixture used, imp.
sulfurous acid and alcohol, me clearly read from Fig. 3.
In a comparison with Figs. 1 and 2, it is seen that exploitation
of this synergistic effect no longer necessitates an increase in
the concentration of the sulfurous acid to 40,000 Pam (Fig. 1) or an
increase in temperature to 50C (Fig. 2).
In comparison with yeasts, the Canada of the mold Aspergillus Niger
are easier to kill with sulfurous acid. The concentration ox H2S03
and the temperature exert only a very slight influence fig. 4).
A D value of D22 = 2.45 seconds already results at a concentration
of only 10,000 Pam a room temperature.
The synergistic effect resulting from a combination of H2S03 with
alcohol (ethanol) is, at D22 = 1.8 seconds, not very pronounced
(Fig. 5).
The mold Mocker is more resistant to ~2S03 than Aspergillus Niger
The time curves or killing Mocker at different concentrations of
S03 and at different temperatures are shown in Figs. 6 and 7. A
value in the region of a few seconds is achieved at 30,000 Pam
(22C) or at 10,000 Pam (60C).
The synergistic effect of a mixture of H2S03 and alcohol is also
clearly scan in the case of Mocker (Figs. 8 and 9). The effectiveness
of sulfurous acid in killing Mocker is improved by the addition of
alcohol both at room temperature 122C) and at SEIKO.
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Acetobacters have a quite high resistance to sulfurous acid. As
shown in Figs. 10 and 11, the acetobacter G].uconobacter may be
killed only slowly Neither a high concentration of ~2S03 nor an
increase in temperature are able to bring about any substantial
improvement in this respect. A technically exploitable, swift
killing of germs with corresponding D values within the range of a
few seconds, preferably under 3 seconds, cannot be achieved even
with the high concentration of 100,000 Pam at room temperature.
The D22 value is still 15 seconds.
In the case of Gluconobacter, the addition of ethanol to the sulfurous
acid proves to be a decisive factor in intensifying the microbicidal
effect. A combination of 30,000 Pam assay and alcohol (30 by
weight ethanol) acts synergistically at room temperature and enables
the Gluconobacter to be killed quickly at D22 = approx. 1.6 seconds
fig. 12)
If the temperature is increased to 50C, a comparable D value
(D50 1.5 seconds) may also be achieved with a lower concentration
of sulfurous acid (20,000 Pam) and a lower alcohol content (15 by
weight) (Fig. 13).
~cetobacter acetic like Gluconobacter, has a high resistance to
sulfurous acid. This acetobacter can, however, be killed quickly at
a D value of 1.7 seconds due to the synergistic effect of a mixed
solution of sulfurous acid and alcohol (20,000 Pam / 15 by weight)
(Fig. 14).
The time taken to kill the lactic acid bacterium Leuconostoc
dextranicum as a function of the temperature is illustrated in
Fig. 15. The greatest number of bacteria are killed at 60C at a
concentration of 10,000 Pam. The D60 value is 1.45 seconds.
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A synergistic effect of the inventive mixture of sulfurous acid and
alcohol is also clearly discernible in the case of L. dextranicum.
Fig. I shows that the germ-killing effect owe the sulfurous acid
(20,000 Pam Nazi at pi 3.0) is considerably intensified by adding
ethanol (15 % by weight). A D value of D22 1.5 seconds may be
achieved.
The synergistic effect of the mixture H2S03/alcohol is still very
apparent when other alcohols are used instead of ethanol. The
addition of l-propanol (Fig. 17), 2-propanol (Fig. 18), l-butanol
(Fig. 19), buttonhole (Fig. 20) and namely alcohol (Fig. 21) to
the sulfurous acid contributes clearly to intensifying the
microbicidal effect on yeasts (Saccharomyces cerevisLae). The
alcohol l-propanol, in combination with sulfurous acid, accelerates
the killing ox molds - ~ucor - (Fig. 22), acetobacters - Gluconobacter -
(Fig. 23) and lactic acid bacteria - L. dextranicum - (Fig. Al
To summarize, it may be ascertained that a synergistic effect of
sulfurous acid and alcohol is clearly apparent when killing the germs
tested on the basis of the test results described above and illustrated
in the Figures. The combination of sulfurous acid and alcohol enables
the germs to be killed quickly with D values of between 1 and 2 seconds
when the concentration of H2S03, the alcohol content and the
temperature are selected accordingly. The mixed solution suggested
may therefore be used to advantage on a large technical scale, in
particular for sterilizing plastic-coated packing materials for the
packaging of fruit juice and wine or for sterilizing wine bottles.
The alcohol used is preferably ethanol although it is also possible
to make use of other alcohols. The concentration of sulfurous acid
is preferably between 10,000 and 100,000 Pam, in particular between
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10,000 and 50,000 Pam in relation to the mixture. Particularly
favorable concentrations of alcohol are in the range of 10 to 30
by weight, especially I to 20 by weight in relation to -the mixture.
Suitable temperatures for the inventive treatment are between 20 and
80C, preferably between 20 and 50C. The sulfurous acid is best
obtained by reacting saline sulfur compounds with acid. Apart from
Nazi, Nazi is also suitable both alone or in combination with
the aforesaid substance. The acid used for adjusting the pi value
is preferably citric acid.
The jacking material may be treated by dipping, spraying or the like
in or with the inventive mixed solution which is synergistically
effective. It is also possible to apply the saline sulfur compound,
e.g. Nazi, from which the sulfurous acid is obtained, to the
packing material separately and then to dissolve it by adding an
acidified, aqueous alcohol solution.
The results are summarized in the following Tables.
It is particularly favorable to spray the sterilizing mixed
solution onto the packing material and then cause it to vaporize
due to heating subsequent to its reaction time.
The invention is particularly favorable for use in bottling or
packaging wine since wine often contains sulfurous acid and alcohol
in any case. This means that no "foreman substances" which could
impair the quality of the wine need be used for sterilizing the
packing material.
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