The present invention relates to disinfectant compositions which
are especially, but not exclusively, useful for the cleaning-in-place (CIP) of
equipment used in the food industry.
A typical situation encountered in food industry CIP is the cleaning
of the insides of dairy equipment such as that used in the ultra high temperature
(UHT) treatment of milk where the apparatus is soiled by organic matter, mainly
fat and protein, and inorganic deposits, mainly insoluble calcium salts such as
the carbonate, phosphate and oxalate. Naturally, as well as removing both the
organic and inorganic soiling, it is necessary to sanitize the equipment, i.e.
to reduce the number of potentially harmful micro-organisms to an acceptable level.
To ensure that sanitization occurs, a composition for this purpose
must contain at least one anti-microbial component. One class of anti-microbial
substance comprises those of the quaternary ammonium type. For example, UK Patent
Specification GB 1 239 641 describes disinfectant cleaning compositions including
such a quaternary ammonium compound. These compositions also contain a hydroxycarboxylic
acid and a detergent active (surfactant) agent. However, such compositions are
not sufficiently effective in disinfection applications of the kind described
in the preceding paragraph.
It has also previously been described that quaternary ammonium anti-microbials
and/or those of the substituted guanidine type may be combined with acid components
to provide disinfection of parts of the human body, for example in US Patents
4,420,484 and 4,213,961, in European Patent Specification EP 4,719 and UK Patent
Specification GB 1,296,630. Since these components are intended to come into intimate
contact with human tissue, they are not sufficiently aggressive to be efficacious
in sanitization of hard surfaces encountered in the food industry.
We have now found that disinfection of surfaces in applications of
the kind described above can be effected to a degree superior to that possible
with existing market products by providing a sanitizing composition comprising:-
(i) a quaternary ammonium anti-microbial agent and/or a substituted guanidine
(ii) an organic acid; and
(iii) an inorganic acid.
One surprising property of this composition derives from the fact
that the microbial effect of quaternary ammonium anti-microbials in combination
with inorganic acids is known to decrease with decreasing pH. However, we have
found that incorporation of an organic acid significantly imporves the fungicidal
effect. We have observed this to be most marked with organic acids having from
one to four carbon atoms, either with or without a hydroxyl group additional to
that forming part of the carboxyl moiety. Examples of such organic acids are formic,
lactic and citric acids. The organic acid can also be of a cyclic nature such as
benzoic acid. However, whilst preferred, in the context of the invention in its
widest sense, these specific organic acids are not to be considered limiting and
further non-limiting examples of suitable organic acids are elaborated hereinbelow.
In general, of course the invention includes compositions containing
more than one example of any of the ingredients defined in classes (i)-(iii) above.
Within these classes, it is generally preferred that the total quantity quaternary
ammonium anti-microbials (when present) should be from 0.01 to 50%, most preferably
from 0.5 to 30%, especially from 1 to 25%. These percentages and unless the context
requires otherwise, all others throughout this specification, are by weight. As
a general guide, any one quaternary ammonium anti-microbial agent may be present
from 0.5 to 15%, preferably from 1 to 12.5%.
Generally, the total quantity of substituted guanidine anti-microbials
(when present) may be from 0.01 to 25%, preferably from 0.2 to 15%, most preferably
2 to 12.5%. The amount of any single substituted guanidine anti-microbial agent
may for example be from 0.2 to 12.5%, preferably from 2 to 10%.
Generally, the total quantity of organic acids present may be from
0.1 to 75%, preferably from 0.5 to 50%, especially from 5 to 35%. The total amount
of any single organic acid may for example be from 0.2 to 20%, preferably from
1 to 12.5%.
Generally, the total quantity of inorganic acids present may be from
1 to 99%, preferably from 10 to 95%, most preferably from 20 to 55%. The total
amount of any single inorganic acid may for example be from 0.5-60%, preferably
The quaternary ammonium anti-microbial agent (if present) may be
of any of such agents known to those skilled in the art, for example in W. Gump,
Disinfectants and Antiseptics, Vol. 7, in "Encycl. Chem. Technol.", Kirk-Othmer
Eds., 3rd Edn., pp 793-832, in the Patent literature references quoted above or
in any of patent specifications EP 131,394, EP 110,568, GB 2,133,689, GB 2,074,043,
GB 1,155,501, and US 4,256,731.
The substituted guanidine anti-microbial agent (if present) also
may be any known to those skilled in the art, for example any described generically
or specifically in the patent literature references above or in German Patent
Specification DE 2,332,383, UK Patent Specification GB 1,431,945 or in any of US
Patents 3,934,002; 2,684,924; 4,053,636; 2,990,425; 3,468,898; 3,855,140 and 4,622,834.
Preferred compositions according to the present invention comprise
both a quaternary ammonium and substituted guanidine anti-microbial agent.
More especially, the substituted guanidine agent may be a biguanide.
In general, such a biguanide agent may be a monomeric or polymeric compound which
includes one or more units of formula
Where R¹-R&sup4; can be any of a variety of moieties. For example
R¹ and R² independently may be bonds or C1-4
alkylene chains optionally
substituted by a phenyl radical (which itself optionally may be substituted by
one or more suitable substituents such as alkyl or alkoxy), and R³ and R&sup4;
independently may be hydrogen, C1-12 alkyl or C7-12
and R¹ with R³, and independently, R² with R&sup4; may form cyclic moieties.
The substituted guanidine (including biguanide) agents include the
acid addition salts thereof, which may or may not form due to the presence in the
composition of the present invention, of the organic and the inorganic acid.
One preferred biguanide is that sold by ICI under the Tradename "Vantocil
As stated, the organic acid is believed to be necessary to enhance
the anti-microbial properties of the composition. Although some preferred examples
are recited above, in general such organic acids include those containing one
or more carboxylic, hydroxycarboxylic or sulphonic acid groups. As well as those
mentioned previously, examples of suitable organic acids are acetic acid, salycilic
acid and hydroxybenzoic acid derivative anti-microbials such as are described in
W. Gump supra.
The inorganic acid is preferably a strong mineral acid such as sulphuric,
hydrochloric, nitric, orthophosphoric (otherwise known as "phosphoric"), boric
or perboric acid. Of these, phosphoric acid is especially preferred.
Experimental results have demonstrated the unexpected phenomenon
that compositions of the present invention which comprise both phosphoric and sulphuric
acids are especially efficacious in removing not only calcium oxalate deposits,
but also protein soiling. This effect is most marked when the phosphoric acid is
present in the range 25-35%, preferably 5-25% by weight and the sulphuric acid
in the range 2.5-25%, preferably around 30% by weight.
Compositions according to the present invention may also comprise
one or more accessory ingredients.
Thus, although the composition comprising only components (i)-(iii)
has some inherent ability to remove fatty organic soil, its action can be enhanced
by incorporation of one or more detergent active (surfactant) agents. These are
well known in the art and may in general, be selected from non-ionic, cationic,
zwitterionic and amphoteric agents. Those of the non-ionic kind are preferred.
Examples of the detergent active (surfactant) materials which can
be used for these compositions are described in detail in "Surface Active Agents
and Detergents", Volumes I and II by Schwartz, Perry and Berch. In general, when
such materials are present, their total presence may amount to from 0.01 to 25%,
preferably from 0.1 to 5%, especially from 1 to 2.5%. As a rule, the total amount
of any one such active may be from 0.1 to 3%, preferably from 1 to 2%.
Other optional ingredients include solvents, hydrotropes, thickeners,
abrasives and other anti-microbial agents. In general, the remainder of any such
composition may comprise water. To ensure optimum removal of inorganic soil, it
is preferred that compositions according to the invention have a pH of 5 or less,
especially 4 or less and most preferably, less than 4.
Of these ingredients, hydrotropes (when present) in total may for
example be included at from 0.01 to 25% by weight, preferably from 0.2 to 15%,
especially from 1 to 7.5%. In general, any one hydrotrope may be present at from
0.1 to 10%, preferably 1 to 5%.
Thickeners (when present) in total may for example be included at
from 0.01 to 10% by weight, preferably from 0.02 to 5%, especially from 0.2 to
2.5%. As a rule, any one hydrotrope may be present at from 0.05 to 30% by weight,
preferably from 0.5 to 20%, especially from 1 to 15%.
Other (non-quaternary and other than substituted guanidine) anti-microbials
which may be included are sodium benzoate, as well as those of the amine oxide
and dioxide kind. Generally, it is preferred to include both sodium benzoate and
an amine oxide. As a rule, such other anti-microbials (when present) may be included
at from 0.1 to 40% by weight, preferably from 0.5 to 20%, most preferably from
1 to 15%. Normally, any one such other anti-microbial may be present at from 0.1
to 15%, preferably from 0.2 to 10%.
The compositions of the present invention may be applied to any suitable
surface it is desired to cleanse but they are especially suitable for equipment
CIP. It is preferred that they be applied in diluted form. Generally, this dilution
may be at from 0.05 to 10% in aqueous medium but especially from 0.2 to 2%. The
appropriate working concentration or concentration range will of course vary according
to the amount of each ingredient in the undiluted composition. These values can
be determined by suitable tests (for example as referred to herein) which will
readily be apparent to those skilled in the art of formulating disinfectants.
In most situations, the cleansing step requires leaving the composition
in contact with the surface for a suitable period of time, followed by rinsing
with water. Within the CIP area, applications in the food industry are eminently
suitable, for example in dairies and breweries. Thus, as well as the UHT equipment
cleaning referred to above, another application is in the cleaning of bright beer
tanks in the brewing industry. (In the context of the present invention, "cleansing"
and "cleaning" include sanitisation/disinfection but not necessarily to the degree
of killing substantially all micro-organisms present).
The present invention will now be further elaborated by way of the
following non-limiting Examples.
Examples 1-7 are sanitizing compositions made-up according to the
following table (quantities are % by weight):-
The compositions of Examples 1-7 were tested in various aqueous concentrations
in a standard suspension test for reduction of numbers of Saccharomycescerevisiae
at 4°C (method as described in B van Klingeren, "Two-Tier Test
System for the Evaluation of Disinfectants", Ph.D. Thesis, University of Utrecht,
except using S.cerevisiae
instead of Candidaalbicans).
Results are presented as the minimum use concentration of composition
which demonstrated a log decimal reduction (LDR) greater than 4.0.
Examples 8 and 9
Other forms of composition according to the invention, particularly
suited to open plant cleaning is set forth below. Quantities are in % by weight
and the intended applied concentration is from 4-10%.
(i) one or more quaternary ammonium anti-microbial agents and/or one or more
substituted guanidine anti-microbial agents;
(ii) one or more organic acids; and
(iii) one or more inorganic acids.
2. A composition according to claim 1, wherein when present, the total quantity
of quaternary ammonium anti-microbial agent(s) is from 0.01 to 50% by weight;
when present, the total quantity of substituted
guanidine anti-microbial agent(s) is from 0.01 to 25% by weight;
the total quantity of organic acid(s)
is from 0.1 to 75% by weight; and
the total quantity of inorganic acids
present is from 1 to 99% by weight.
3. A composition according to claim 2, wherein when present, the total quantity
of quaternary ammonium anti-microbial agent(s) is from 0.5 to 20% by weight;
when present, the total quantity of substituted
guanidine anti-microbial agent(s) is from 0.2 to 15% by weight;
the total quantity of organic acids is
from 0.5 to 50% by weight; and
the total quantity or inorganic acids
present is from 20 to 55% by weight.
4. A composition according to any preceding claim, comprising both at least
one quaternary ammonium anti-microbial agent and at least one substituted guanidine
5. A composition according to any preceding claim comprising a substituted
guanidine anti-microbial agent which is a polymeric biguanide.
6. A composition according to any preceding claim, wherein the inorganic acid
content comprises phosphoric acid and sulphuric acid.
7. A composition according to any preceding claim, further comprising a surfactant.
8. A composition according to claim 7, wherein the surfactant is a non-ionic
9. A composition according to any preceding claim, further comprising sodium
benzoate and an amine oxide anti-microbial.
10. A method of sanitising a surface, comprising applying to said surface,
a composition according to any of claims 1-9.
11. A method according to claim 10, wherein said composition is applied at
from 0.05 to 10% in aqueous dilution.
12. A method according to claim 11 when dependent on claim 2, wherein the composition
is applied at from 0.2 to 2% in aqueous dilution.