A cleaning composition comprising mono-rhamnolipid and di-rhamnolipid, characterised in that the ratio of the total wt% of mono-rhamnolipid to the total wt% of di-rhamnolipid lies in the range 95:5 to 45:55.
This invention relates to cleaning compositions comprising rhamnolipid having components di-rhamnolipids and mono-rhamnolipids.
Rhamnolipids are a class of glycolipid. They are constructed of rhamnose combined with beta-hydroxy fatty acids. Rhamnose is a sugar. Fatty acids are ubiquitous in animals and plants. The carboxyl end of the fatty acid end is connected to the rhamnose. Rhamnolipids are compounds of only three common elements; carbon, hydrogen, and oxygen. They are a crystalline acid. Rhamnolipids may be produced by strains of the bacteria Pseudomonas aeruginosa. There are two major groups of rhamnolipids; mono-rhamnolipids and di-rhamnolipids.
Mono-rhamnolipids have a single rhamnose sugar ring. A typical mono-rhamnolipid produced by P. aeruginosa is L-rhamnosyl-β-hydroxydecanoyl-β-hydroxydecanoate (RhaC10C10). It may be referred to as Rha-C10-C10, with a formula of C26H48O9. Mono-rhamnolipids have a single rhamnose sugar ring. The IUPAC Name is 3-[3-[(2R,3R,4R,5R,6S)-3,4,5-trihydroxy-6-methyloxan-2-yl]oxydecanoyloxy]decanoic acid.
Di-rhamnolipids have two rhamnose sugar rings. A typical di-rhamnolipid is L-rhamnosyl-L-rhamnosyl-β-hydroxydecanoyl-β-hydroxydecanoate (Rha2C10C10). It may be referred to as Rha-Rha-C10-C10, with a formula of C32H58O13. The IUPAC name is 3-[3-[4,5-dihydroxy-6-methyl-3-(3,4,5-trihydroxy-6-methyloxan-2-yl)oxyoxan-2-yl]oxydecanoyloxy]decanoic acid.
In practice a variety of other minor components with different alkyl chain length combinations, depending upon carbon source and bacterial strain, exist in combination with the above more common rhamnolipids. The ratio of mono-rhamnolipid and di-rhamnolipid may be controlled by the production method. Some bacteria only produce mono-rhamnolipid, see
In various publications mono-rhamnolipids have the notation Rha-, which may be abbreviated as Rh or RL2. Similarly di-rhamnolipids have the notation Rha-Rha or Rh-Rh- or RL1. For historical reasons "rhamnolipid 2" is a mono-rhamnolipid and "rhamnolipid 1" is a di-rhamnolipid. This leads to some ambiguity in the usage or "RL1" and "RL2" in the literature. Throughout this patent specification, we use the terms mono- and di-rhamnolipid in order to avoid this possible confusion. However, if abbreviations are used R1 is mono-rhamnolipid and R2 is di-rhamnolipid. For more information on the confusion of terminology in the prior art see the introduction to
The following rhamnolipids have been detected as produced by the following bacteria: (C12:1, C14:1 indicates fatty acyl chains with double bonds).
Rhamnolipids produced by P. aeruginosa (mono-rhamnolipids):
Because rhamnolipids are produced in various chemical formulas, each with a different HLB, it is known that rhamnolipids can be produced or mixed to have a range of foaming properties.
Rhamnolipids are an anionic surfactant with both hydrophilic end and a lipophilic end. When their concentration increases to a certain level it is known that the rhamnolipids join together inside a liquid in a micelle.
It has been suggested that rhamnolipids with two shorter fatty acids are more active in reducing surface tension and as an emulsifier. Those rare rhamnolipids with a single fatty acid chain are not as effective.
The bacterium Pseudomonas aeruginosa is found naturally in soils, in water, and on plants. Metabolically, P. aeruginosa is chemoheterotrophic, generally aerobic, utilizing a wide range of organic compounds for sources of carbon and nitrogen.
There are over 100 strains of P. aeruginosa on file at the American Type Culture Collection (ATCC). There are also a number of strains that are only available to manufacturers of commercial Rhamnolipids. Additionally there are probably thousands of strains isolated by various research institutions around the world. Some work has gone into typing them into groups. Each strain has different characteristics including how much rhamnolipid is produced, which types of rhamnolipids are produced, what it metabolizes, and conditions in which it grows. Only a small percentage of the strains have been extensively studied.
Through evaluation and selection, strains of P. aeruginosa can be isolated to produce rhamnolipids at higher concentrations and more efficiently. Strains can also be selected to produce less byproduct and to metabolize different feedstock or pollutants. This production is greatly affected by the environment in which the bacterium is grown.
Various documents have proposed to use Rhamnolipids in detergent compositions.
For our analysis of this prior art Rhamnolipid a known amount of JBR425 was acidified to pH 3 using 12M HCl and placed in a refrigerator overnight. The supernatant was then extracted three times using a 2:1 mixture of Chloroform and Ethanol. The solvent was then removed by rotary evaporation and the isolated rhamnolipid mixture was then re-dissolved in methanol.
The process of separating and characterising the mixture was carried out using an HPLC connected to an Ion Trap Electrospray ionisation Mass Spectrometer. The mode of ionisation was in negative mode with a scanning range of 50-1200Da. The column used to separate was a Phenomenex luna C18 250 x 4.6mm 5 µm column. The mobile phase: water (mobile phase A) and acetonitrile (mobile phase B) were used to separate via a gradient of 60:40 (A:B) changing to 30:70 (A:B) over 30 minutes. The system was then held for 5 minutes before returning to the start conditions all at a flow rate of 0.5ml/min. The injection volume was 10 µl.
Example 4 provides further data about combinations of nonionic surfactant and rhamnolipids. Two rhamnolipids are used: RL-BNS n=10 is probably the one used in example 1 (ratio mono-rhamnolipid: di-rhamnolipid not given). Table 5 shows that shorter chain length BioEm-LKP outperforms the RL-BNS on a weight for weight basis (more moles used) for EMPA 104 (Indian ink with olive oil on cotton polyester). However, on WFK20D (mixed particulates in sebum on cotton polyester) the longer chain material was superior (as it was in examples 1 and 3), despite being used at a lower molar concentration. It is not possible to determine from the information in this document if this could have been due to the ratio of mono:di rhamnolipids in the samples. There is no data for beef fat. Tests were all carried out using a 0.5g/l dried rhamnolipid/standard surfactant blend.
From our analysis carried out in 2007 and from more recent analysis of commercially available Rhamnolipids from pseudomonas aeruginosa, where both mono- and di-rhamnolipids are produced, the mix is generally di-rhamnolipid (R2) dominated.
According to the present invention there is provided a detergent composition comprising mono-rhamnolipid and di-rhamnolipid and an optional co-surfactant wherein the weight ratio of mono-rhamnolipid to di-rhamnolipid lies in the range 95:5 to 45:55.
The optional co-surfactant is preferably present at a level of at least 5 wt% and is more preferably synthetic anionic surfactant, most preferably linear alkyl benzene sulphonate. Especially with C12-14 alkyl chains. Preferably, the amount of synthetic anionic surfactant exceeds the total amount of Rhamnolipid. The total amount of surfactant in the composition desirably lies in the range 10 to 40 wt%.
The detergent composition preferably has less than 2 wt% builder and is more preferably unbuilt. That is, zeolite, phosphate or silicate builders are absent.
The detergent composition is preferably a liquid detergent composition and if citric acid builder is present, it is limited to a maximum level of 2 wt%. The composition is especially useful as a laundry detergent and may be used with advantage for washing in water with a low water hardness of less than 5°F. A process whereby the laundry and the composition are washed in presoftened water is particularly advantageously used with the compositions of the invention.
The rhamnolipids of the defined ratios are used to remove fatty soils from laundry, especially from cotton cloths. Removal of soils from cotton is of increasing concern because many of the sophisticated soil removal and soil release technologies included in modern laundry detergents work best on polyester cloths. Accordingly, it is advantageous to combine the detergent system of the present invention with a polyester soil release polymer.
Changing the relative amounts of mono and di rhamnolipids used in a detergent composition according to the invention leads to enhanced cleaning benefits and synergies with synthetic anionic surfactants. The best synergy is believed to occur with C12-14 alkyl benzene sulphonate synthetic anionic surfactant. This surfactant is commonly employed in laundry detergent compositions and is typically used with a nonionic surfactant, such as the ethoxylated nonionic surfactant used in
A preferred use of the compositions is for the removal of the fatty soil beef fat.
A large proportion of biosurfactants are generated by the action of bacteria on renewable feedstocks and are increasingly becoming more and more viable options as sustainable replacements of current synthetic surfactants. Within the current portfolio of biosurfactants that are currently commercialised, Rhamnolipids, formed by the degradation of oils and fats by Pseudomonas Aeg, show poor cleaning benefits when used at concentrations of components generated by the bacterial breakdown process. However, when the main mono and di rhamnolipid components of the expressed rhamnolipids are extracted and reblended to produce blends not normally generated by bacterial sources they show enhanced performance. Moreover, by producing blends and mixing with either synthetic anionic surfactants further enhancement in detergency can be achieved.
The detergent composition may comprise other ingredients commonly found in laundry liquids.
The detergent composition may comprise other ingredients commonly found in laundry liquids. Especially polyester substantive soil release polymers, hydrotropes, opacifiers, colorants, perfumes, other enzymes, other surfactants, microcapsules of ingredients such as perfume or care additives, softeners, polymers for anti redeposition of soil, bleach, bleach activators and bleach catalysts, antioxidants, pH control agents and buffers, thickeners, external structurants for rheology modification, visual cues, either with or without functional ingredients embedded therein and other ingredients known to those skilled in the art. The composition is preferably a liquid and is advantageously packaged in either a multidose bottle or in a unit dose soluble pouch.
The invention will be further described with reference to the following non-limiting examples.
Table 3 shows the detergency data on stained woven cotton from four formulations containing biosurfactants. Examples 1 and 2 are according to the invention and Examples A and B are comparative for Jeneil and Jeneil LAS. Jeneil is the commercially available Rhamnolipid JBR425 with composition analysed to be that in table 1. All examples are systems composed of 0.5 gram per litre surfactant. Detailed compositions are given in Table 2.
The material used in Examples 1 and 2 below is 50% di-Rhamnolipid and 50% mono-Rhamnolipid (by weight).
A = 100% Jeniel JBR 425
B = 40% Jeniel JBR 425, 60% LAS
1= 50/50 mono-rhamnolipid/di-rhamnolipid
2= 40% 50/50 mono-rhamnolipid/di-rhamnolipid, 60% LAS
Total Surfactant levels used were calculated to deliver 0.5gpl in the wash. For a 20 ml dose of the compositions in Table 2, this amounts to 1.33 gram per litre of the full composition in a washing machine with a capacity of 15 litres. Washing was done for 30 min in Tergotometers at 25°C and 4°FH. Wash pH was circa 8. Cleaning results for several stains are shown in Table 3.
The data for cleaning of Lard especially show enhanced cleaning with the 50/50 mono-rhamnolipid/di-rhamnolipid surfactant, when compared to combinations with LAS or with the commercially available Jeneil RBR425 Rhamnolipid with composition as analysed and given in table 1.
This list of references cited by the applicant is for the reader's convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.