Note: Descriptions are shown in the official language in which they were submitted.
W096/07723 0 a~ ~ 2~0 PCTIUS9S/11105
A CLEANING COMPOSITION COMPRISING LIPASE AND AMYI ASE ENZYMES
FIELD OF THE INVENTION
This invention relates to cleaning compositions, and particularly to cleaning
compositions for use on ovens.
BA~CKGROIJND AL~T
Cleaning compositions for use on sl~rf~ s that have been subjected to Sp~ hlg by
food products at high temperatures are well known. Such sl~rf~res, for example in ovens,
quickly become coated with food residues that can become baked on at high temperatures
These residues from food subjected to high te~ c.dlul~;s will be described herein as burnt-on
food soils.
Removal of burnt-on food soils is considerably more difficult than removal of food
stains from, for example, textile m~t~ri~l~. The high temp~ldlulcs to which such food soils
have been subjected causes their removal to require very aggressive chlomic~l compositions
that are usually either very acidic or more usually very ~lkslline. In particular, known oven
cleaning compositions tend to have a quite extreme pH and particularly tend to be strongly
20 ~lk~lin~ since it has been believed that burnt-on food soils can only be removed by such
aggressive m~t( ri~l~. These compositions are often used under severe treating conditions,
including oxi~li7in~ and recl~cin~ conditions at high te~ .dLIlres.
Cleaning compositions have been proposed that contain active enzymes, such as
washing powders and d~tclgen~. However, these compositions typically have been proposed
25 for washing conditions a~ç~-.ate for ~extile m~ttori~l~7 for example L~ )el~Lures below
55C and pH's below 11.
SUMMARY OF THE INVENTION
The liquid, enzyme-based cle~nin~; composition of the invention is sllrnm~ri7~1 in
that it includes a lipase en_yrne active at a pH of from 10 to 14; an amylase enzyme also
W 0 96/07723 0 ~ ~ ~9 260 - 2 - PC~rrUS9S/11105
active at a pH of from 10 to 14; at least one alkali-stable non-ionic or anionic s--nf~rt~nt; an
alkali metal silicate; and an inert diluent. The composition is buffered at a pH of 10 to 14.
The method of the invention is summarized in that a method of cleaning a surface '
bearing burnt-on food soils includes the steps of applying the composition of claim 1 to the
5 food soils at a cool surface temperature; allowing the food soils to soften; and removing the
food soils. Preferably the surface tcl,lp~,ldl~re does not exceed about 50C.
DETAILED DESCRIPTION OF THE INVENTION
According to the present invention there is provided a cleaning composition for burnt-
on food soils, particularly suitable for use on ovens, that is enzyme based. The enzyme
colll~ollent is active in the pH range of 10-14. Incorporation of enzymes into cleaning
compositions of this type would not normally have been considered since enzymes are
known to be ra~her fragile and to be deactivated rather easily. It is surprising to find an
15 enzyme-co~ -g composition that is effective particularly at pH's in excess of 10.
According to the present invention, there is provided an enzyme-based cleaning
composition compri~ing a lipase enzyme, an amylase enzyme, an alkali-metal silicate, and an
alkali-stable s~ rt~nt which composition is buffered to m~int~in the pH of the composition
in the range from 10-14, and preferably from 10-12.5. The o~Limulll pH is approximately
20 12.5. The invention also provides a method of cle~ning surfaces that have been subjected to
food residues at high lenl~.dlu.cs, such as ovens and other cooking sl~ rçs, ~tili7.ing the
said enzymatic composition for cle~ning .
All amounts stated in this description are based on the total weight of the composition
of the invention. The enzymes used in the invention are preferably ~ik~liphilic. If enzymes
25 so le~ign~ted are not commercially available, enzymes can be selected on the basis of
activity against the relevant components of the soil (e.g. amylase against starch components)
as a function of pH. Those skilled in the art can readily identify commercially or otherwise
available enzymes with sufficient activity at the pH of the composition to be useful as
components of a cl~ning composition and particularly those that would have an activity at
30 the o~lhllu~ll pH ofthe product, 12.5.
W096/07723 _3 PCT/U~95/11105
Lipase enzymes used in the present invention are those enzymes that promote
hydrolysis of triglycerides into mono and diglycerides, glycerol, and free fatty acids, all of
which are more soluble than the original fat triglyceride. A nurnber of different lipase
enzymes are commercially available, having been used in fabric cleaning formulations for the
5 removal offat-co~ ;lli--g stains such as the stains resulting from cooking fat, salad oils,
butter, and fat based sauces. A preferred lipase for use in the present invention is Lipolase,
m~nllf~ctured by Novo Nordisk Indus~ry. This is a 1,3-specific lipase that cleaves ester
bonds in the positions 1 and 3 of a triglyceride.
Amylase enzyrnes are those that hydrolyze starches to soluble ~lextrin~ and
10 oligosaccharide. Amylases have been used in fabric cleaning compositions to remove starch-
cont~inin~ stains, such as those made from pasta, chocolate, and gravy products, by way of
example, only. Amylase enzymes hydrolyze 1,4-alpha glucosidic bonds in an amylose or
amylopectin. A pl~r~ d amylase is Termamyl~ which is a commercially available enzyme
m~nllf~rtllred by Novo Nordisk Industry, being alpha amylase prepared by fPrment~tion of
15 Rnci~u~ licheniformis.
The composition of the invention can contain a protease as an optional, additional
enzyme. Proteases are enzymes that hydrolyses protein to peptides that can be readily
dissolved. Proteases have previously been incorporated into fabric cleaning compositions
such as laundry detergents. A preferred ploteasl;; is the cornmercial product Savinase(~ also
20 available from Novo Nordisk Industry. Savinase~ is a proteolytic enzyme prepared by
submerged ferment~tiQn of an alkalophilic species of Bacillus and is an endo-protease of the
serine type, with broad substrate specificity.
Each of the enzymes types used are present in from 0.1 to 4% by weight of the
composition. The particular enzymes disclosed above are only non-limiting examples of
25 their types. It should be noted that a wide range of commercially available lipase, amylase,
and protease enzymes are available.
Since the compositions of the invention are generally inten-11?cl for oven cleaning, they
should be of sufficient viscosity to hold them on a vertical surface for an effective time, i.e.
for a time sufficient to effect or at least f~.ilit~te the removal of burnt-on food soils. In order
30 to achieve such a viscosity, it may be nPceS~ry to add a thickener, in addition to the other
colll~ollents of the co~ u~ilion. The amount of the thickener will depend on the nature of
wo96/o7723 ~ g9 26 0 PCl`/US95/11105
the thickener itself and of the other components in the composition. It may be that the other
components in the composition, along with their other ~lOp~l lies, also will act as a thickener
for the purpose of giving the a~lv~fiate viscosity to the composition, making unnecessary
the addition of a separate component specifically as a thickener. A composition primarily
5 inten~f d for application to burnt-on food soils on horizontal ~nrf~ces, such as stove tops,
could be in a more fluid form.
When present as a separate component that is provided primarily to increase
composition viscosity, the thickener should be present in the range of from 0.05 to 6 percent
by weight and preferably from 0.2 to 6 percent. The thickeners can be selected from the
10 group con~i~tin~ of inorganic materials, organic polymeric materials, and cc,ln~lible
mixtures thereof.
Suitable inorganic thickeners include, by way of example only, colloidal silica,smectite clays such as bentonite, attapulgite, Laponite, m~gn~sium alumino-silicate, and
compatible mixtures thereof. Polymeric organic thickeners can be biopolymers (such as
15 ~nth~n or welan gum) or synthetic polymers (such as polyacrylates or hydrophobically
modified polyu~ ~le). Coll~ cially available examples of such synthetic polymers may
be selected from the CARBOPOL(~) polymers produced by B.F. Goodrich or the
RHEOVIS~ polymers available from Allied Colloids. Preferably the thicken~r is a
cro~linked polyacrylate. Commercial examples of cros~linked polyacrylates may be selected
20 from the ACRYSOL (~ polymers produced by Rohm & Haas. When the thickener is ahydrophobically modified polyul~;lL~le thickener, it should more preferably be present in the
range of from 1 to 2 percent by weight.
The alkali metal silicate compounds in the composition assist in fat break-down and
provide alkalinity. They also assist as d~ builders and act as corrosion inhibitors.
25 Particular alkali metal silicates that can be employed are those having a Na2O:SiO2 ratio in
the range 1:2 to 2:1. The ~Lillluln range is from 1:1 to 2:1. These alkali metal silicates will
usually be present in the range 5-35 weight percent and preferably 5-25 weight percent,
although the precise amount may depend on the nature of the surfactant.
The amount of silicate will also be rl~ttqrmine~l to some extent by the nature of the
30 buffer used. Thus the pl~r~ d buffer employing an alkali metal carbonate, and preferably
sodium c~b~ , may allow a reduced amount of silicate to be present. Decreasing the
0~ 99260
WO 96107723 PCT/US9~/lllO~i
- 5 -
amount of silicate present, though it cannot be reduced to 0, is advantageous in that it reduces
the amount of electrolyte, which increases the shelf life of the formula. Also, silicates
sometimes have adverse effects on skin, making it desirable to reduce the amount of silicates
so as to ~ ç the side effects of the composition, should it come in contact with
5 ull~lolccted skin.
The composition of the invention must be buffered, although it may be that
components in the composition, e.g. the silicate, will provide a sufficient bu~clillg effect so
as not to require an independent buffer. The buffer colll~ollcllL~ in the composition should be
selected to retain the composition's pH in the range of from 10-14, preferably from 10-13,
10 and optimally at about 12.5. If a specific buffer is required, a wide variety of buffer
compositions are available and known to those skilled in the art. Carbonate buffers and
particularly alkali metal (e.g. sodium) carbonate buffers are ~lercllcd because of the high pH
ofthe colll~osilion. Preferably carbonate is added in amounts ranging from 0.5 to 12 weight
percent.
To enable the composition to wet and penetrate the m~teri~l~ to be rernoved, thecomposition p lcr~ bly co~t~inC a surfactant. Pler~.lcd sllrf~t~nt~ are those that are alkali
stable and have an HLB (lly~uphile-lipophile balance) in the range of 12-20 and preferably
in the range 13-16. The HLB is a measure of the relative water solubility of the snrf~ct~nt
and gives an indication of the relative ~JlU~l lions of hydrophobic and hydrophilic portions in
20 the molecule. The ~llrf~rt~nt~ preferably are non-ionic, but anionic ~ulr~cl~ll~ may be used.
It is only rarely that a cationic snrf~ct~nt will be operable.
Preferable non-ionic ~nrf~l~t~nt~ include nonyl phenol ethoxylates (preferably 9 and
20 mole ethoxylates), alkyl glucosides, C l 1 oxo-alcohol ethoxylates co~ at least 7
moles of ethylene oxide, short chain fat~ acid polyethylene glycol ethers CO~ i"g at least 5
25 moles of ethylene oxide, and iso-C 13 oxo-alcohol ethoxylates cont~ining at least 8 moles of
ethylene oxide, or compatible nlixlule~ thereof. Alkyl and aryl capped m~t~ri~l~ can also be
employed.
Typical anionic surfactants are ~lk~lin.o metal and alkylolamine alkyl sulfonates,
p~U~lll sulfonates, and ~lk~line metal alkyl phenol sulfonates.
Normally one would use either an anionic sllrf~rt~nt or a non-ionic ~,-, r~ as
ll~ixlulGs of anionic and non-ionic sllrf~ t~nt~ tend to be ineffective. Mixtures of surfactants
W0 96/07723 ~ 2 8 ~ 6 - PCT/US95/11105
are not normally compatible because of the high ~lk~linity, tending to separate. However, by
very careful choice of the ~ ~-;ate sllrf~ct~nt system, anionic/non-ionic sllrf~rt~nt
mixtures are possible and are not excluded from the invention.
The amount of sllrf~ct~nt present is usually from 0.5 to 10 weight percent. With5 anionic surf~rt~nt~, it is also desirable that a co-builder be present, partly to assist in avoiding
the salting-out of the surfactant. A wide variety of co-builders are used with anionic
surfactants in the various applications of these sllrf~t~nt~ Preferred co-builders that are
useful for anionic systems are alkali metal polyphosph~tP~ alkali metal salts of organic acids,
and alkali metal salts of polymeric acids. More preferably the co-builder is at least one of
10 STPP (sodium tri polyphosphate) and alkali metal salts of citric acid, gluconic acid,
polyacrylic acid, and modified polyacrylic acid. Compatible mixtures of the above
mentioned co-builders can be ~ltili7to~1 In addition, the silicate component of the composition
can contribute as a co-builder. Preferably the co-builder (other than the silicate component)
is present in the amount of 0.5-12 percent by weight.
Co-builders are usually less nPcess~ry in non-ionic surfactant systems since there is
less likelihood of inactivation by calcium ions. Nevertheless, co-builders may still be
n.oces~ry if it is found that the calcium ions present in the composition are having an adverse
effect.
Preferably the compositions include hydrotropes, i.e. compounds that have the
20 property of increasing the aqueous solubility of any insoluble organic chemicals present.
Useful hydrotropes are cllm~nl~slllfonate, sodium _ylene sulphonate, phosphate esters, and
sodium toluene sulphonate. Compatible lmxlules of the above mentioned hyd-~ tlopes can be
used if desired. Preferably said h~dl~ opes are present in the amount of 0.2-2.5 percent by
weight.
Removal of bDt-on food soils can be enhanced by the use of penetrating solvents.The presence of these solvents also can assist in stabili_ing the en7yme content of the
composition. Suitable solvents are those organic liquids that soften and penetrate into resin-
type materials, for example those solvents found in paints. The particularly l ler~ d
solvents are those that are found also to enhance the stability of the en_ymes. Suitable
30 solvents are glycol ethers (e.g. those sold under the trade name Cellosolve), esters, glycol
ether acet~t~, methyl pyrrolidone, and 1,3-dimethyl-2-imiti~7~lidinone. Cnmp~tihle
~ W096/~7723 ~ 9 260 PCT~S95/lllos
ulc;s of the above mentioned solvents can be used. More preferably, the mentioned
solvents are present in the amount of from 2-10 percent by weight.
- The compositions of the invention can contain other conventional cleaning
composihon colll~onents, if they do not m~t~n~lly detriment~lly affect the enzymatic
5 pr~llies of the system. Such components include, for example, sequestering agents, dyes,
bleaches, bleach activators, foam control agents, and fragrances.
The composition of the invention also includes appropriate diluents for application,
although the composition may be ~l~a.cd in a concenb-ated form for dilution prior to use.
The preferred diluent (apart from the penetrating solvents discussed above) is water and will
10 usually comprise at least 70% and preferably at least 75% by weight of the composition.
The composition of the invention can be applied directly without further dilution, for
example by water, and can be applied by brushing or by spraying from a spray device,
including an aerosol dispenser. In the case of an aerosol dispenser, the inclusion of a foaming
agent in the composition will result in a foam that covers the surface to be treated. The
15 surface to be treated should preferably be cold, which shall mean commonly experienced
room l~ cldlules. If warm, the surface should not be of a L~ dLule s~lffi~iently high as
to be deleterious to the enzymes in the composition. Tel,lpe.~l lres not in excess of 50C are
d.
The invention will be illustrated by the following Ex~llples.
wo 96/07723 ~ 6 ~ 8 - PCT/USg5/1110
FXAl\IPT.F 1.
The following were combined in the stated percentages by weight. Compositions
described in Columns A and B are examples of specific formulations that have been made,
5 while Column C states the pl~r~lled ranges of ingredients:
Name Percentage
Comp Comp
C
ACRYSOL* ICS-I - 5.0 5.0 0.05-6
A commercial polyacrylate resin supplied by
Rohm & Haas.
Sodium Metasilicate - 5.0 5.3 5-35
A commercial product METSO 510*
supplied by Crosfields Plc
ETHYLAN* BAB 20 - 1.0 1.1 0.5-10
Nonionic surfactant supplied by Akcros
Chemicals
Hexyl CELL(~SOLVE* - 3.0 2.7 2-10
Ethylene glycol monohexyl ether supplied by
Union Carbide
Sodium Carbonate 1.5 1.2 0.5-12
Sodium Citrate 5.0 3.8 0.5-12
LIPOLASE* 100LTYPEEX- 2.5 2.5 0.1-4
A commercial lipase supplied by Novo
Nordisk Tnd~ ries
TERMAMYL* 300 TYPE DX - 2.0 2.0 0.1-4
A commercial amylase supplied by Novo
Nordisk Industry
Water 75.00 76.4 70-75
* Trade Name or Registered Trade Mark
The compositions of Example 1 were viscous fluids which, when applied to the
vertical walls of an oven, r~m~inPd in position for sufficient time to effect cleaning. When
the compositions were applied to a surface co~ ."i,~ l with burnt-on food soils in a test of
10 the type recommen~le~l by the Vitreous Enamel Council, the soils softened and were easily
removable after 16 hours.
WO 96/07723 ~ 2 1 9 ~ 2 6 Q PCT/US95/11105
F,XAl\IPT,F 2.
The following were combined in the stated percentages by weight. The composition
described in Column A is an example of a specific formulation that has been made, while
Column B states the ~.c;r~lled ranges of ingredients:
Name Percentage
Carbopol*- 2.0 0.05-6
A commercial cross-linked polyacrylate
supplied by B. F. Goodrich
Sodium Metasilicate - 5.3 5-35
A commercial product METSO 510* supplied
by Crosfields Plc
ETHYLAN* BAB 20 - 1.0 0.5-10
Nonionic surfactant supplied by Akcros
Chemie~lc
Hexyl CELLOSOLVE* - 2.6 2-10
Ethylene glycol monohexyl ether (supplied by
Union Carbide)
Sodium Carbonate 1.1 0.5-12
Sodium Citrate 3.8 0.5-12
LIPOLASE* 100L TYPEEX- 2.5 0.1-4
A colnm~orcial lipase supplied by Novo Nordisk
Industry
TERMAMYL* 300 TYPE DX - 2.0 0.1-4
A commercial amylase supplied by Novo
Nordisk Industry
Water 797 70 75
* Trade Name or Regi~L~d Trade Mark
The composition of Example 2 was a viscous fluid which, when applied to the
vertical walls of an oven, rem~ined in position for sufficient time to effect cle~nin~ When
applied to a surface cn"lS.",i,.i1le-1 with burnt-on food soils in a test ofthe type leco~ en-~ed
by the Vitreous Enamel Council, the soils softened and were easily removable after 16 hours.
The invention is not limited to the Examples, which are only illustrative. Tn~1e~-1 the
invention is in accordance with the claims.
