EP3322792B1

EP3322792B1 - Hdw composition comprising activated citrus fiber and abrasive particles

Info

Publication number: EP3322792B1
Application number: EP16736418.1A
Authority: EP
Inventors: Leonardus Marcus Flendrig; Stephanie LAM; Valentina LA MOLA; Maria Julia SALGADO MATINA; Orlin Dimitrov Velev; Krassimir Petkov Velikov
Original assignee: Unilever PLC; Unilever NV
Current assignee: Unilever PLC; Unilever NV
Priority date: 2015-07-14
Filing date: 2016-06-29
Publication date: 2020-06-17
Anticipated expiration: 2036-06-29
Also published as: MY188687A; AR105328A1; WO2017009042A1; EP3322792A1; ZA201800219B

Description

FIELD OF THE INVENTION

The present invention relates to a cleaning composition. In particular, the invention relates to a cleaning composition comprising detergent surfactant, electrolyte and abrasive particles of vegetable origin and defibrillated primary cell wall material comprising microfibrils.

BACKGROUND TO THE INVENTION

Cleaning compositions comprising detergent surfactants are well-known in many fields of application, for instance for hard surface cleaning, dishwashing, laundry washing, skin care, scalp and hair care, oral care. Most surfactant compositions have a tendency to foam, in particular once they are diluted upon application. In many such applications, especially where consumers prepares suds or lathers from the cleaning composition themselves, such foaming is perceived as a sign of detergency. Often it is even perceived as a prerequisite for detergency. Therefore, good foam formation is a very desirable characteristic for many cleaning compositions. It is especially desirable that the foamy or frothy layer, once formed, does not disappear readily but remains in place for the consumer to be observed. However, optimising a formulation to provide such optimal foaming may negatively affect other characteristics. In particular, a well-known way to enhance foaming is by using a larger quantity of surfactant present in a formulation. From a sustainability point of view, this is very undesirable. Therefore, it would be desirable to provide an alternative way of enhancing the stability of the foam formed from cleaning compositions.
Hand dish wash cleaning compositions suitable for washing dishes are known. Such compositions should not only have proper foaming performance but also be able to deliver excellent grease and soil removal. Cleaning of tough soil on hard surfaces may be difficult and abrasive particles may be included to provide better cleaning performance. However, particles may negatively influence the foaming performance.
WO 2014/142651 discloses use of particulate cellulose material (for instance from sugar beet pulp) for keeping gas bubbles suspended in a fluid water-based composition. The cellulose particles have a volume-weighted median major dimension within the range of 25-75 µm, as measured by laser light diffractometry and should not be defibrillated. Similarly, WO 2014/017913 discloses a liquid detergent product comprising the same type of non-defibrillated particulate cellulose material.
WO 2012/52306 relates to externally structured aqueous liquid detergent compositions, in which non-defibrillated citrus fibre is used to suspend particulates. WO 2013/160024 relates to similar compositions in which the tendency of activated citrus fibre to form visible residues on the wall of a container is overcome by the addition of polyacrylates. WO 2014/82951 discloses a dentifrice comprising calcium carbonate particles and non-defibrillated citrus fibre to improve the cleaning efficacy of those particles.
US 2008/0108714 discloses surfactant-thickened systems comprising microfibrous cellulose (bacterial cellulose) to improve the suspending properties of the system. It particularly discloses the combination of bacterial cellulose, xanthan gum and carboxymethyl cellulose is such systems.
US 6 241 812 relates to sanitisers and disinfectants. It discloses the combination of reticulated bacterial cellulose with cationic surfactant and a co-agent (such as cationic hydroxyethyl cellulose, pregelatinized cationic starch, conventional cationic starch, cationic guar gum, gum tragacanth and chitosan) to prepare acid-stable cellulose fibre dispersions, with reduced precipitation and flocculation of the cellulose fibres.
US 5 998 349 discloses descaling formulations comprising between 0.05 and 1.5 wt-% of cellulose microfibrils having at least 80% of cells with primary walls, a pH of less than or equal to 2 and at least one detergent surfactant. The cellulose fibre is used to provide a pseudoplastic rheological profile, which is stable over time.
WO 2014/082835 discloses liquid hard surface cleaning compositions comprising 10 to 95 wt% liquid solvent, 1 to 75 wt% abrasive, and 0.025 to 5 wt% activated citrus fibre.
It is an object of the present invention to provide cleaning compositions that provide enhanced sensory properties to the consumer. Thus, it also is an object of the present invention to provide cleaning compositions providing enhanced foam stability, in particular without increasing the amount of detergent surfactants. Desirably, the enhanced foam stability is provided upon dilution of the cleaning composition when it is used. It is another object of the invention to provide such cleaning compositions that display enhanced foam stability, without negatively affecting other desirable properties of the composition, such as their detergent efficacy, their physical appearance and/or other sensory attributes. It is yet another object of the invention to provide cleaning compositions that have a reduced environmental impact, without affecting other desirable properties.

DEFINITION OF THE INVENTION

We have found that one or more of these objects can be achieved by the cleaning composition of the present invention. In particular, it was surprisingly found that primary cell wall material comprising microfibrils, which has been defibrillated to a suitable level, such that the composition homogeneity parameter of the composition has an appropriate value can be used to provide cleaning compositions that upon dilution display good foamability and longer-lasting foams, even in the presence of particles.
Accordingly, in a first aspect the invention provides a cleaning composition, comprising

a. water;
b. 5 to 30 wt-% of one or more detergent surfactants;
c. 0.1 to 8 wt-% electrolytes;
d. 0.1 to 5 wt-% abrasive particles; and
e. 0.1 to 4 wt-% of defibrillated primary cell wall material comprising microfibrils;

^-1

the primary cell wall material is sourced from plant parenchymal tissue;
at least 80 wt% of the microfibrils is smaller than 50 nm in diameter; and
the cleaning composition has a composition homogeneity parameter CHP of at least 0.030.

DETAILED DESCRIPTION OF THE INVENTION

Any feature of one aspect of the present invention may be utilised in any other aspect of the invention. The word "comprising" is intended to mean "including" but not necessarily "consisting of" or "composed of." In other words, the listed steps or options need not be exhaustive. It is noted that the examples given in the description below are intended to clarify the invention and are not intended to limit the invention to those examples per se. Similarly, all percentages are weight/weight percentages unless otherwise indicated. Except in the operating and comparative examples, or where otherwise explicitly indicated, all numbers in this description indicating amounts of material or conditions of reaction, physical properties of materials and/or use are to be understood as modified by the word "about". Unless specified otherwise, numerical ranges expressed in the format "from x to y" are understood to include x and y. When for a specific feature multiple preferred ranges are described in the format "from x to y", it is understood that all ranges combining the different endpoints are also contemplated. For the purpose of the invention ambient temperature is defined as a temperature of about 20 degrees Celsius.

Cleaning composition

The cleaning composition according to any aspect of the invention is a composition intended to aid in cleaning, typically in a domestic environment. The precise format and formulation of the composition can suitably be adapted to the intended type of application, as is generally known by the skilled person. The cleaning composition comprises water, one or more detergent surfactants and defibrillated primary cell wall material. In addition, the cleaning composition may suitably comprise other ingredients that are typical for such cleaning compositions. For example, the composition may also comprise non-detergent surfactants, preservatives, etcetera.

Surfactant

There are few limitations on the type or the amount of the detergent surfactants. The detergent surfactant may be one type of surfactant, or a mixture of two or more surfactants. Synthetic surfactants preferably form a major part of the one or more detergent surfactants. Thus, the one or more detergent surfactants are preferably selected from one or more of anionic surfactants, cationic surfactants, non-ionic surfactants, amphoteric surfactants and zwitterionic surfactants. More preferably, the one or more detergent surfactants are anionic, nonionic, or a combination of anionic and nonionic surfactants. Mixtures of synthetic anionic and nonionic surfactants, or a wholly anionic mixed surfactant system or admixtures of anionic surfactants, nonionic surfactants and amphoteric or zwitterionic surfactants may all be used according to the choice of the formulator for the required cleaning duty and the required dose of the cleaning composition.
In general, the surfactants may be chosen from the surfactants described in well-known textbooks like "Surface Active Agents" Vol. 1, by Schwartz & Perry, Interscience 1949, Vol. 2 by Schwartz, Perry & Berch, Interscience 1958, and/or the current edition of "McCutcheon's Emulsifiers and Detergents" published by Manufacturing Confectioners Company or in "Tenside-Taschenbuch", H. Stache, 2nd Edn., Carl Hauser Verlag, 1981; "Handbook of Industrial Surfactants" (4th Edn.) by Michael Ash and Irene Ash; Synapse Information Resources, 2008.
The anionic surfactant may include soap (salt of fatty acid). A preferred soap is made by neutralisation of hydrogenated coconut fatty acid, for example Prifac® 5908 (ex Croda). Mixtures of saturated and unsaturated fatty acids may also be used.
Nonionic detergent surfactants are well-known in the art. A preferred nonionic surfactant is a C12-C18 ethoxylated alcohol, comprising 3 to 9 ethylene oxide units per molecule. More preferred are C12-C15 primary, linear ethoxylated alcohols with on average 5 to 9 ethylene oxide groups, more preferably on average 7 ethylene oxide groups.
Examples of suitable synthetic anionic surfactants include sodium lauryl sulphate, sodium lauryl ether sulphate, ammonium lauryl sulphosuccinate, ammonium lauryl sulphate, ammonium lauryl ether sulphate, sodium cocoyl isethionate, sodium lauroyl isethionate, and sodium N-lauryl sarcosinate. Mostly preferred the synthetic anionic surfactants comprise the synthetic anionic surfactant linear alkylbenzene sulphonate (LAS). Another synthetic anionic surfactant suitable in the present invention is sodium alcohol ethoxy-ether sulphate (SAES), preferably comprising high levels of sodium C12 alcohol ethoxy-ether sulphate (SLES). It is preferred for the composition to comprise LAS.
In some embodiments, the one or more detergent surfactants preferably comprises synthetic anionic with nonionic detergent active materials and optionally amphoteric surfactant, including amine oxide.
In other embodiments, it is preferred that the one or more detergent surfactants comprise two different anionic surfactants, preferably linear alkyl benzene sulphonate and a sulphate, for example LAS and SLES.
Typical examples of suitable amphoteric and zwitterionic surfactants are alkyl betaines, alkylamido betaines, amine oxides, aminopropionates, aminoglycinates, amphoteric imidazolinium compounds, alkyldimethylbetaines or alkyldipolyethoxybetaines.
The cleaning composition according to any aspect of the invention comprises 5 to 30 wt-% of one or more detergent surfactants. The cleaning composition preferably comprises at least 6 wt-%, more preferably at least 7 wt-%, even more preferably at least 8 wt-%, even more preferably at least 9 wt-%, still more preferably at least 10 wt-%, and yet more preferably at least 12 wt-% of the one or more detergent surfactants. The cleaning composition preferably comprises up to 28 wt-%, more preferably up to 26 wt-%, even more preferably up to 24 wt-%, still more preferably up to 22 wt-%, still more preferably up to 20 wt-% and yet more preferably up to 18 wt-% of the one or more detergent surfactants. Thus, the cleaning composition preferably comprises from 6 to 28 wt-%, more preferably from 7 to 26 wt-%, even more preferably from 8 to 24 wt-%, still more preferably from 9 to 22 wt-%, still more preferably from 10 to 20 wt-% and yet more preferably from 12 to 18 wt-% of the one or more surfactants.

Electrolytes

Electrolytes are water-soluble organic and inorganic salts (other than anionic surfactants), wherein the cation is chosen from alkali metals, alkaline earth metals, ammonium and mixtures thereof and the anion is chosen from chloride, sulphate, phosphate, acetate, nitrate and mixtures thereof. Particularly useful are magnesium, potassium, sodium and ammonium chloride and/or sulphate. Preferably the electrolytes comprise magnesium sulphate and more preferably the electrolytes comprise at least 50 wt-%, even more preferably at least 80 wt-%, still more preferably at least 90 wt-% and still even more preferably at least 95 wt-% of magnesium sulphate, calculated on total weight of electrolytes.
The cleaning composition according to any aspect of the invention comprises 0.1 to 8 wt-% electrolytes. The cleaning composition preferably comprises at least 1 wt-%, more preferably at least 2 wt-%, and even more preferably at least 3 wt-% electrolytes.
The cleaning composition preferably comprises up to 7 wt-%, more preferably up to 6 wt-%, and even more preferably up to 5 wt-% of electrolytes. Thus, the cleaning composition preferably comprises from 1 to 7 wt-%, more preferably from 2 to 6 wt-%, and even more preferably from 3 to 5 wt-% electrolytes.

Abrasive particles of vegetable origin

The abrasive particles are of vegetable origin, meaning that the particles are derived from vegetable material like e.g. apricot stones, corn cob grit, walnut shells or olive stones. Some vegetable materials may interact with the cleaning composition matrix and e.g. absorb water and/or other ingredients present thereby modifying the properties of the abrasive particles. It is also possible that vegetable materials interact with the cleaning composition matrix in such a way that e.g. colour can leach out of the vegetable material. Interaction between the abrasive particles and the cleaning composition matrix may not be desirable from a technical and/or consumer point of view. It was surprisingly found that olive stones show less colour leaching. Preferably at least part of the abrasive particles are derived from olive stones and more preferably the abrasive particle consist essentially of particles derived from olive stones.
The abrasive particles preferably have a size of 12/40 US mesh, more preferably 14/35 US mesh and even more preferably 16/30 US mesh. Put differently, the abrasive particles preferably have a size of respectively 1.680 to 0.400 mm, more preferably 1.410 to 0.500 mm mesh and even more preferably 1.190 to 0.595 mm.
To ensure proper cleaning performance whilst reducing scratching damage the abrasive particles preferably have a Mohs hardness of 1 to 7, more preferably a Mohs hardness of 2 to 6, and even more preferably a Mohs hardness of 3 to 5 (kg/mm2)
Preferred abrasive particles are derived from olive stones having a size of 16/30 US mesh.
The cleaning composition according to any aspect of the invention comprises 0.1 to 5 wt-% abrasive particles. The cleaning composition preferably comprises at least 0.2 wt-%, more preferably at least 0.4 wt-%, and even more preferably at least 0.5 wt-% abrasive particles. The cleaning composition preferably comprises up to 4 wt-%, more preferably up to 3 wt-%, and even more preferably up to 2 wt-% abrasive particles. Thus, the cleaning composition preferably comprises from 0.2 to 4 wt-%, more preferably from 0.4 to 3 wt-%, and even more preferably from 0.5 to 2 wt-% abrasive particles.
For usability the abrasive particles should be evenly distributed throughout the cleaning composition and stay afloat, i.e. not sink to the bottom, as this could result in product without abrasive particles when dosed from a bottle and provide less cleaning performance. It was surprisingly found that the combination of an electrolyte and defibrillated primary cell wall material comprising microfibrils allows for the abrasive particles to stay afloat whilst still providing good dosing performance, i.e. not too thick or too thin.

pH

The cleaning composition according to any aspect of the invention has a pH from 2 to 9, preferably a pH from 5 to 7.

Viscosity

The cleaning composition according to any aspect of the invention has a viscosity from 0.5 to 6.0 Pa.s when measured at a shear rate of 21 s^-1 at 25 °C. More preferably the viscosity is from 0.6 to 5 Pa.s, even more preferably from 0.7 to 4 Pa.s, still more preferably from 0.8 to 3 Pa.s, still even more preferably from 0.9 to 2 Pa.s and yet more preferably from 1.1 to 1.7 Pa.s.
For the purpose of the present invention the viscosity is measured using a HAAKE™ Viscotester™ 550 Rotational Viscometer with MV2 cylinder (DIN 53018).

Primary cell wall material

For the purpose of the invention "primary cell wall material" is defined as the cell wall material from which essentially all cold water soluble components have been removed, i.e. at a temperature of around 20 degrees Celsius. This can easily be achieved by washing with water.
The primary cell wall material is sourced (i.e. prepared) from plant parenchymal tissue. The microfibrils in the cleaning composition according to the invention are microfibrils obtained from primary cell wall material. The source of the plant parenchyma cells may be any plant that contains plant parenchyma cells having a cellulose skeleton. A plant cell wall typically contains cellulose and hemicellulose, pectin and in many cases lignin. This contrasts with the cell walls of fungi (which are made of chitin), and of bacteria, which are made of peptidoglycan. Primary plant cell walls contain lignin only in minor amounts, if at all. The primary cell wall material used in the cleaning composition according to the invention may comprise some lignin, like less than 10 wt% calculated on total amount of cell wall material, but preferably does not contain substantial amounts of lignified tissue. Preferably the primary cell wall material consists essentially of non-lignified tissue as understood by the skilled person in the area of plant biology.
Preferably the source of primary cell wall material is selected from parenchymal tissue from fruits, roots, bulbs, tubers, seeds, leaves and combination thereof; more preferably is selected from citrus fruit, tomato fruit, peach fruit, pumpkin fruit, kiwi fruit, apple fruit, mango fruit, sugar beet, beet root, turnip, parsnip, maize, oat, wheat, peas and combinations thereof; and even more preferably is selected from citrus fruit, tomato fruit and combinations thereof. A most preferred source of primary cell wall material is parenchymal tissue from citrus fruit.
The primary cell wall material may optionally have undergone several pre-treatment steps before it is brought in the defibrillated state. Such pre-treatments include but are not limited to heating, cooking, washing, refining, depectinating, as long as the defibrillated cell wall material comprising microfibrils is present in the cleaning composition as required by the present invention. Hence, the parenchymal tissue may for instance also be provided in the form of a puree.

Microfibrils

In the context of the present invention, the microfibrils present in or derived from the primary cell wall material, are the strongly self-associated fibrous structures typically found in plant cell walls. In the native plant tissue, they are conventionally present in the form of aggregates from a few tens of nanometres to a few micrometres. These aggregates consist of the elementary microfibrils. These elementary microfibrils are well-known. A typical microfibril generally comprises about 36 aligned beta-1-4-glucose polymer chains.
The cleaning composition according to the invention comprises 0.1 to 4 wt-% of defibrillated primary cell wall material comprising microfibrils. Here, the wt-% of the total composition is based on the dry weight of the primary cell wall material from which essentially all cold water soluble components have been removed (i.e. the insoluble fraction, which is also understood as the fibre fraction). The amount of defibrillated cell wall material may suitably be selected to obtain the desired effect and depends on the overall product format. It may for instance also depend on the typical level of dilution upon application and the amount of defibrillated cell wall material required in the lather upon its formation to provide the enhanced foam stability to the lather. Preferably, the amount of defibrillated cell wall material in the cleaning composition according to the invention is from 0.15 to 3 wt-%, more preferably from 0.15 to 2 wt%, more preferably from 0.2 to 1.5 wt%, even more preferably from 0.2 to 1 wt% and still even more preferably from 0.2 to 0.7 wt-%.
Preferably, the microfibrils are obtained from the primary cell wall material by removing soluble and unbound sugars, protein, polysaccharides, oil soluble oils, waxes and phytochemicals (e.g. carotenoids, lycopene). This is suitably achieved using well known techniques including cutting up the cell wall material, cooking, washing, centrifugation, decanting and drying as is well-known to the skilled person.
Preferably the primary cell wall material comprises at least 50 wt-% of microfibrils, more preferably at least 60 wt %, even more preferably at least 70 wt %, still more preferably at least 80 wt %, even still more preferably at least 90 wt % and most preferably the primary cell wall material consists essentially of microfibrils. Here, the wt-% is based on the dry weight of the primary cell wall material and the microfibrils.
Plant cell walls, especially in parenchymal tissue contain hemicelluloses and pectin in addition to cellulose. Thus, the microfibrils in the primary cell wall material may typically comprise cellulose, hemicellulose, and pectin. However, the primary cell wall material of the invention does not necessarily contain hemicellulose and/or pectin. The hemicellulose or part thereof may have been removed when the primary cell wall material is prepared from the plant parenchymal tissue. Therefore, the primary cell wall material of the invention optionally comprises hemicellulose, like for example in an amount of 0 to 40 wt%. Preferably the primary cell wall material comprises hemicelluloses, preferably in an amount of up to 40 wt%, like for example from 5 to 40 wt%, and more preferably in an amount from 10 to 30 wt%.
Likewise the pectin or part thereof may have been removed when the primary cell wall material is prepared from the plant parenchymal tissue. Therefore, the primary cell wall material of the invention optionally comprises pectin, like for example in an amount of 0 to 30 wt%. Preferably the primary cell wall material comprises pectin, preferably in an amount of up to 30 wt%, like for example from 5 to 30 wt%, and more preferably in an amount from 10 to 20 wt%.
Preferably the primary cell wall material of the invention comprises hemicelluloses and pectin.
The primary cell wall material in the cleaning composition of the invention comprises defibrillated cell wall material, i.e. the microfibrils that make up the fibers present in the primary cell wall are at least partially disentangled without breaking them. It is the degree of disentanglement that provides the cleaning composition of the present invention with its surprising properties. The CHP parameter correlates to this degree of disentanglement.
Preferably the average length of the microfibrils from the defibrillated primary cell wall material is more than 1 micrometer and preferably more than 5 micrometers.
At least 80 wt% of the microfibrils is smaller than 50 nm in diameter. Preferably at least 80 wt% of the microfibrils is smaller than 40 nm in diameter, more preferably smaller than 30 nm, even more preferably smaller than 20 nm and still more preferably smaller than 10 nm. The microfibril diameter can be suitably determined using the method described in the Examples section below.
The primary cell wall material is suitably defibrillated by subjecting it to mechanical energy and/or cavitation thereby disentangling the cellulose-containing microfibrils.
This can be done as part of the process for obtaining the microfibrils from the primary cell wall material, thus resulting in isolated defibrillated cell wall material comprising microfibrils. Alternatively, the primary cell wall material can be combined with one or more of the other ingredients of the cleaning composition (including for example the surfactant) wherein the resulting mixture is subjected to mechanical energy and/or cavitation thereby disentangling the microfibrils in the cellulose fibers. The required level defibrillation can also be arrived at by a succession of various such disentanglement treatments, for example by first subjecting a dispersion of the primary cell wall material to a high shear treatment, and at later stage subjecting a premix of the cleaning composition to another high shear treatment. Alternatively, if the preprocessing of the primary cell wall material provides sufficient disentanglement to yield the required level of defibrillation in the final cleaning composition, it may suffice if the manufacturing steps in which the primary cell wall material is combined with the other constituents of the cleaning composition include only mixing steps of relatively low shear.

The cellulose in the microfibrils in the defibrillated primary cell wall material in any of the compositions of the present invention preferably has an average degree of crystallinity of less than 50%. Preferably the average degree of crystallinity of the cellulose in the microfibrils is less than 40%, more preferably less than 35% and even more preferably less than 30%. The table below shows the average degree of crystallinity of typical sources of cellulose microfibrils. It shows that the cellulose in primary cell wall material sourced from plant parenchymal tissue typically has a degree of crystallinity of less than 50 wt-%.

Table 1: Average degree of crystallinity of cellulose (all polymorph cellulose I)

Source	Average degree of crystallinity (%)
Tomato fibers	32
Citrus fiber (Citrus Fiber AQ+N)	29
Nata de Coco	74
Cotton	72
Wood pulp fiber (Meadwestvaco)	61
Sugar beet fibre (Nordix Fibrex)	21
Pea fibres (PF200vitacel)	42
Oat fibres (780 Sunopta)	43
Corn hull (Z-trim)	48
Sugar cane Fiber (Ultracel)	49

The average degree of crystallinity can be suitably determined according to the described in the Examples section below.

The composition homogeneity parameter CHP

According to the first aspect of the invention, the cleaning composition has a composition homogeneity parameter CHP of at least 0.030.The CHP provides a measure for the extent to which the primary cell wall material has been defibrillated, based on confocal scanning laser microscopy (CSLM) performed on a standardised sample comprising the defibrillated cell wall material. The CHP of the cleaning composition is established by the following protocol. The protocol to establish the parameter includes three parts: sample preparation, CSLM microscopy to obtain micrographs of the sample, and digital image analysis to calculate the CHP value.
Thus, the protocol includes the sample preparation steps of

a. preparing 300 ml of an aqueous, concentration-standardised sample at room temperature from the cleaning composition, wherein the concentration-standardised sample comprises the microfibrils contained in the defibrillated primary cell wall material at a concentration of 0.100 wt-% with respect to the weight of the standardised sample;
b. evenly distributing the primary cell wall material over the concentration-standardised sample volume by agitating the sample with a Silverson overhead mixer equipped with a small screen having 1 mm holes at 2000 rpm for 60 seconds;
c. dying the microfibrils by providing a 0.5 %-w/v aqueous stock solution of Congo Red dye and contacting an aliquot of the standardised sample with an amount of the Congo Red solution, wherein the amount is 1.0 vol-% with respect to the volume of the aliquot of the standardised sample;
d. filling a sample holder suitable for performing CSLM with an aliquot of the dyed standardised sample.

In step c, for example, 2 mL of the standardised sample is contacted with 20 µl of the Congo Red solution. In order to ensure even distribution of the dye throughout the sample, it may for instance be gently shaken.
The sample holder of step d suitably includes two cover slides separated by a spacer comprising a bore of sufficient volume to enable the recording of sufficient micrographs for digital image analysis as described below.
To obtain micrographs, the protocol includes the following step:
e. imaging the dyed standardised sample with a confocal scanning laser microscope equipped with a diode-pumped solid state laser emitting at a wavelength of 561 nm and operated at a fixed laser power, using a 10x objective with a numerical aperture of 0.40, and thereby recording at least 25 independent micrographs at a resolution of 1024×1024 pixels where each pixel represents a sample size of within the range of 1490 by 1490 nm to 15400 by 1540 nm, adjusting the intensity and gain settings such that in every image between 0.1 and 5% of the pixels are saturated and recording the micrographs at a colour depth of at least 8 bits per pixel.
The CHP is a measure relating to the primary cell wall material. Therefore, micrographs should be recorded whilst avoiding imaging of air bubbles or the sample edge. Likewise, care should be taken to avoid imaging other objects of macroscopic dimensions that do not originate from the defibrillated primary cell wall material. This may conveniently be accomplished for instance by removing such objects of macroscopic dimensions during sample preparation in step a or by avoiding them in the sample whilst collecting micrographs.
Typically, one or more photomultiplier tubes are used as the light detectors in the microscope. Preferably the microscope is equipped with three photomultiplier tubes (PMTs). Independent micrographs are micrographs that are non-overlapping, both in the x-y plane and in the z-direction. The micrographs may suitably be recorded at a colour depth higher than 8 bits (for instance at 24 bit RGB), since this can easily be converted to a lower colour depth by well-known means.
The digital image analysis part of the protocol involves the following steps:

f. ensuring that the micrographs are present as or converted to a format with a single intensity value for each pixel;
g. normalising each individual micrograph by recalculating the pixel values of the image so that the range of pixel values used in the image is equal to the maximum range for the given colour depth, thereby requiring 0.4% of the pixels to become saturated;
h. obtaining for each individual micrograph the image histogram and removing spikes from each histogram by visual inspection;
i. for each individual image histogram determining the full width at half maximum (FWHM), by first determining the maximum count in the histogram and the channel containing this maximum count (the maximum channel), then counting the number N of channels between the first channel containing a value equal or higher than half the maximum and the last channel containing a value equal or higher than half the maximum thereby including this first and last channel in the count N, and then calculating the FWHM by dividing the count N by the total number of channels;
j. calculating the composition homogeneity parameter CHP, wherein CHP is the average of the FWHM values obtained for the individual micrographs.

The digital image analysis steps may suitably be carried out using well-known image analysis software including for instance ImageJ. The result of step f should be that the image is of a format wherein the intensity for each pixel is expressed as a single value. This is for instance the case if the image is a "grey-scale" image. In contrast, images in RGB format or a related format having three intensity values per pixel should be converted. This is easily achieved by well-known operations in the field of digital image analysis. An example of a suitable output format would be a grey-scale image with 8bits per pixel.
The normalising operation of step g is generally known as a histogram stretch operation or a contrast stretch operation. The normalisation is performed by allowing a small percentage of pixels in the image to become saturated. Here saturation includes both the minimum and maximum value for the given colour depth. In an 8 bit greyscale image, the minimum value would be 0 and typically displayed as black, whilst the maximum value would be 255 and typically displayed as white. The image histogram of step h is a well-known property for digital images, representing the distribution of the pixels over the possible intensities, by providing the pixel count for each intensity channel. For the purpose of the spike-removal of step h, the value for a particular channel is considered a spike if it is considerably higher than the values of the adjacent channels, typically at least a factor of 1.5 higher. The lower half-maximum channel in step i corresponds to the channel containing a count of half the maximum count that is furthest away from the maximum channel on the low-intensity side of the maximum channel. Analogously, the upper half-maximum channel corresponds to the channel containing a count of half the maximum count that is furthest away from the maximum channel on the high-intensity side of the maximum channel. The FWHM that is obtained in step i will be a value between 0 and 1.
A preferred way of establishing the CHP for the cleaning composition is by following the protocol in the way described in the Examples section below. The above protocol and the Examples provide methods of measuring the CHP. However, the CHP may also be determined by a different protocol, as long as that protocol would lead to the same physical result, i.e. it would yield the same CHP for a particular cleaning composition as the above protocol.
The cleaning composition preferably has a composition homogeneity parameter CHP of at least 0.031, more preferably at least 0.032, even more preferably at least 0.033, even more preferably at least 0.040 and still more preferably at least 0.050. Preferably, the cleaning composition has a CHP of at most 0.20, more preferably at most 0.15, and even more preferably at most 0.10.

EXAMPLES

The invention can be better understood by virtue of the following non-limiting examples.

General

Microfibril characterisation: Degree of crystallinity of cellulose-containing microfibrils

Wide angle X-ray scattering (WAXS) is used to determine the degree of crystallinity, using the following protocol. The measurements were performed on a Bruker D8 Discover X-ray diffractometer with GADDS (General Area Detector Diffraction System) (From Bruker-AXS, Delft, NL) (Part No: 882-014900 Serial No: 02-826) in a theta/theta configuration. A copper anode was used, and the K- alpha radiation with wavelength 0.15418 nm was selected. The instrumental parameters as used are shown in the table below. Table 2: D8 Discover instrumental parameters for WAXS measurements

2θ (9-42°)

Theta 1 10.000

Theta 2 10.000 / 25.000

Detector Bias (kV / mA) 40 / 40

Time (sec) 300

Collimator (mm) 0.3

Detector distance (cm) 25

Tube Anode Cu
The degree of crystallinity Xc was calculated from the following equation: $Xc (%) = \frac{Area crystalline phase}{Area crystalline + amorphous phase} * 100 %$
The areas of the diffraction lines of the crystalline phase were separated from the area of the amorphous phase by using the Bruker EVA software (version 12.0).

Microfibril characterisation: Diameter of microfibrils

Transmission electron microscopy (TEM) was used to directly determine the diameter of the microfibrils (D. Harris et. al. Tools for Cellulose Analysis in Plant Cell Walls Plant Physiology, 2010(153), 420). The dispersion of plant source rich in primary cell wall material was diluted in distilled water resulting in a thin layer of mostly single fibers or single clusters of fibers. The dispersions were imaged on a Carbon only 300 mesh Copper TEM grid (Agar Scientific) and imaged using a Tecnai 20 Transmission electron microscope (FEI Company) operated at a voltage of 200 kV. To enhance image contrast between individual microfibrils, a 2 % phosphotungstic acid solution at pH 5.2 was used as a negative stain. For this the fiber-loaded TEM grids were incubated on 2% phosphotungstic acid and air-dried after removal of the excess of fluid.

Centrifugation force

Where the centrifugation force is given, it is given as a dimensional "relative centrifugal force", which is defined as r ω ²/g, where g = 9.8 m/s² is the Earth's gravitational acceleration, r is the rotational radius of the centrifuge, ω is the angular velocity in radians per unit time. The angular velocity is ω = rpm × 2π / 60, where rpm is the centrifuge "revolutions per minute".

Examples 1 to 6: Hand dishwash composition with enhanced foam stability

Compositions according to the invention were prepared and compared with a comparative example according to WO 2013/160024 A1 .

Preparation of comparative example A

To 1470 grams of demineralised water in a beaker, citrus fibre (Herbacel AQ+ type P ex Herbafoods) was added in an amount to form a 2 wt-% dispersion. The citrus fibre was allowed to hydrate under stirring for 20 minutes. The resulting dispersion was homogenised by passing it over high pressure homogeniser (brand: SPX, model: APV Lab2000), at a pressure of 500 bar. An aliquot of the resulting homogenised dispersion was combined with additional demineralised water (amounts as indicated in Table 3), ensuring even distribution of the defibrillated material over the composition volume by mixing with a Silverson L4RT-A overhead stirrer with a screen with 1 mm round holes at 2000 rpm for 60 seconds. The remaining ingredients as indicated in Table 3 were subsequently added and dissolved by stirring.

Preparation of examples 1, 2, 3, 4, 5, 6

To 1764 grams of demineralised water in a beaker, citrus fibre (Herbacel AQ+ type P ex Herbafoods) was added in an amount corresponding to 0.25 wt-% of the final cleaning composition. The citrus fibre was allowed to hydrate under stirring for 20 minutes. NaOH (sodium hydroxide), LAS (linear alkyl benzene sulphonate), SLES (sodium lauryl ether sulfate), chelator, preservative, and acid were added upon mixing in the amounts as indicated in Table 3. The resulting dispersion was homogenised by passing it over high pressure homogeniser (brand: SPX, model: APV Lab2000), at a pressure of 500 bar (Example 1), 600 bar (Example 2), 700 bar (Example 3), 800 bar (Example 4), 900 bar (Example 5), and 1000 bar (Example 6) respectively. The remaining ingredients as indicated in Table 3 were subsequently added to the resulting homogenised dispersion and dissolved by stirring.

Table 3

Ingredients	Comparative example A	Examples 1-6
Demi-water	58.31	70.56
Herbacel AQ+ type P	-	0.25
Homogenised citrus fibre dispersion (2 wt-% CF)	12.50	-
SLES 1EO (70 wt-%)	5.36	5.36
LAS (97 wt-%)	11.68	11.68
NaOH (50 wt-%)	3.63	3.63
MgSO₄ 7H₂O (44.5 wt-%)	5.62	5.62
Colourants, perfume, preservatives, acids, chelators	1.90	1.90
Olive stones 16/30 US mesh	1.00	1.00
Total	100.00	100.00

Characterisation of the composition: determination of the composition homogeneity parameter CHP

The composition homogeneity parameter CHP was determined for the cleaning compositions of each of the examples 1 - 6, and for comparative example A. The protocol to establish the parameter includes three parts: sample preparation, confocal scanning laser microscopy (CSLM), and digital image analysis to calculate the CHP value.

CHP - sample preparation

120 grams of each example was diluted to a citrus fibre concentration of 0.100 wt-% in demineralised water (yielding 300 g of diluted dispersion) using a 500ml plastic beaker of 80mm in diameter. The mixture was stirred using a Silverson L4RT-A overhead mixer (screen with 1 mm holes) at 2000 rpm for 60 seconds. This mixing step ensures that the citrus fibre is evenly distributed over the diluted sample volume. The sample was allowed to rest for 15 minutes to sediment the particles. Next, 25 grams of sample was taken from the top layer and transferred into a glass vial.
For each example, a volume of 2 mL of the resulting diluted sample was taken with a Finn pipette (Labsystems 4500, H37095) and deposited in an Eppendorf safelock tube. To this 20 µL of a 0.5 w/v % aqueous solution of Congo Red dye was added with a Finn pipette (Labsystems 4027, H56580). The sample was gently shaken to distribute the dye. For imaging, a sample holder was filled with the dyed sample material. The sample holder consisted of two cover slides separated by a spacer. The spacer was a rectangular glass slide of 3 mm thick with a circular hole (0.5 cm diameter) in which the sample could be deposited.

CHP - confocal scanning laser microscopy

Confocal scanning laser microscopy (CSLM) was performed on a Leica TCS-SP5 confocal microscope in combination with a DMI6000 inverted microscope frame. The Diode-Pumped-Solid-State (DPSS) 561 laser emitting at 561nm was used at a fixed laser power of 58% for imaging with the Congo red dye. For detection, the system is equipped with three PMT (photomultiplier tube) detectors.
Images were taken with a 10x objective with a numerical aperture of 0.40 (section thickness 6.23 µm). Tile scans of 2 by 2 images at, at least, 7 different depths were recorded to yield 25 non-overlapping images for analysis. Care was taken not to image the edges of the sample holder; images were taken at a few micrometres distance from the edge. When samples contained air bubbles care was taken to only record images that did not contain any bubbles in the field of view. The PMTs were adjusted by using the "smart gain" and "smart offset" options to prevent over-saturation of the images. Intensity and gain were then adjusted such that between 0.1 and 5% of the pixels are saturated. Best results were obtained at an intensity of 58% and a gain of 800V. The resolution of the images was set to 1024 by 1024 pixels and a line averaging of 3 was used. Each pixel represented a sample area of 1515.2 by 1515.2 nm. After imaging, the individual pictures that make up the tile scan were exported as tiff files with a colour depth of 24bit RGB without incorporating any scale bar (the reconstructed larger tile images were not used in the image analysis).

CHP - digital image analysis

For the image analysis the program ImageJ (freeware downloadable from: http://rsbweb.nih.gov/ij/) was used together with Microsoft Excel. Each image was converted to an 8 bit grey scale before analysis. In the analysis, images are first normalized (i.e. a histogram stretch) using the "enhanced contrast" option of ImageJ, allowing 0.4 % of the pixels to become saturated. After this procedure, the histogram containing the distribution of pixel intensities was calculated. The resulting list containing the number of pixels per channel, in which each channel represents one of the 256 grey scale values in the image was transferred to Microsoft Excel. Before determination of the maximum of the distribution, spikes/outliers were removed from the obtained histogram by visual inspection, considering that a channel displaying a spike has a considerably larger value than the channels immediately adjacent to it (∼2 times or higher). When the histogram displays a smooth distribution, the value of the spike is larger than the maximum of this distribution and located on the right or left of the true maximum. After removal, the maximum of the distribution is determined and divided by two. The full width at half maximum (FWHM) was determined by counting the channels that have a value higher or equal to half the maximum. Any channel containing a zero value that is adjacent to a channel with a count higher than half the maximum is included in the count. The obtained channel count is divided by 256 to yield a FWHM number between 0 and 1 for each individual image. The composition homogeneity parameter is then calculated as the arithmetic average of the FWHM values obtained for the individual images of a particular sample. The reported error is the standard deviation of this average. The characterisation of the examples in terms of their CHP is summarised in Table 4. Table 4: Composition homogeneity parameter CHP

Example CHP standard deviation

A 0.0211 0.0020

1 0.0313 0.0025

2 0.0420 0.0036

3 0.0469 0.0025

4 0.0458 0.0038

5 0.0644 0.0048

6 0.0600 0.0048

Foam stability

The formulations of compositions A and 1-6 were aerated using a Kenwood Chef Classic orbital mixer with a whisk utensil. Demi-water (190 grams) and 10 grams of composition were placed in the bowl of the mixer, followed by mixing for 1 minute at preset 5. The contents of the bowl were transferred to a 1 litre polypropylene beaker (bottom diameter 96 mm, height 182 mm, ex Vitlab). In the beaker a liquid layer and a clearly discernable foam layer are formed within several minutes. The volume of the foam was recorded every 30 minutes up until 150 minutes after the start of the experiment. The resulting foam volumes are presented in Table 5 below. Examples 1 to 6 all had statistically significant more foam volume compared to comparative example A for each recorded incubation time (r ≤ 0.05 according to Student's T-test with two tailed distribution and two sample equal variance).

Table 5: Foam stability of examples 1 - 6 versus comparative example A

Incubation time (min)	Foam volume (ml ± SD, n=5)
Incubation time (min)	A	1	2	3	4	5	6
0	902 ± 15	940 ± 36	950 ± 14	968 ± 15	986 ± 36	990 ± 29	960 ± 26
30	800 ± 38	865 ± 34	870 ± 21	900 ± 16	922 ± 29	928 ± 28	898± 37
60	536 ± 36	648 ± 18	696 ± 31	714 ± 19	756 ± 32	754 ± 34	776 ± 32
90	392 ± 29	434 ± 21	484 ± 32	500 ± 16	544 ± 34	560 ± 23	594 ± 15
120	258 ± 16	296 ± 15	320 ± 14	334 ± 21	366 ± 11	400 ± 14	414 ± 29
150	162 ± 18	196 ± 18	198 ± 11	212 ± 19	250 ± 7	268 ± 22	274± 22
180	80 ± 16	106 ± 9	104 ± 11	134 ± 9	184 ± 9	200 ± 7	180± 14

Table 6 below provides a comparison of the change in foam volume relative to that of the comparative A, according to the formula:

R_{n} (t) = \frac{\frac{V_{n} (t)}{V_{n} (0)}}{\frac{V_{A} (t)}{V_{A} (0)}}

Here, R_n(t) is the relative foam volume of Example n (n being A, 1, 2, or 3) at time t, V_n(t) is the foam volume of Example n at time t.

Table 6: Relative foam volume relative to comparative A

Incubation time (min)	Relative Foam Volume
Incubation time (min)	A	1	2	3	4	5	6
0	1	1.04	1.05	1.07	1.09	1.10	1.06
30	1	1.08	1.09	1.13	1.15	1.16	1.12
60	1	1.21	1.30	1.33	1.40	1.41	1.45
90	1	1.11	1.23	1.28	1.39	1.43	1.52
120	1	1.15	1.24	1.29	1.42	1.55	1.60
150	1	1.21	1.22	1.31	1.54	1.65	1.69
180	1	1.33	1.30	1.68	2.30	2.50	2.25

Table 5 shows that the foam volume decreased over time for all of the Examples 1 to 6. However, as Table 6 shows, the relative foam volume (relative to the volume of the comparative example) increases over time for all six Examples according to the present invention. This demonstrates that the foams of the compositions of the invention decay significantly slower than the comparative foam.

Claims

A cleaning composition, comprising
a. water;

b. 5 to 30 wt-% of one or more detergent surfactants;

c. 0.1 to 8 wt-% electrolytes;

d. 0.1 to 5 wt-% abrasive particles; and

e. 0.1 to 4 wt-% of defibrillated primary cell wall material comprising microfibrils;
wherein the cleaning composition has a pH from 2 to 9;
wherein the cleaning composition has a viscosity from 0.5 to 6.0 Pa.s when measured at a shear rate of 21 s^-1 at 25 °C; and
wherein
• the primary cell wall material is sourced from plant parenchymal tissue;

• at least 80 wt% of the microfibrils is smaller than 50 nm in diameter; and

• the cleaning composition has a composition homogeneity parameter CHP, in accordance with the method herein defined, of at least 0.030.
A cleaning composition according to claim 1, having a composition homogeneity parameter CHP of at least 0.031, preferably at least 0.032, more preferably at least 0.033, even more preferably at least 0.040 and still more preferably at least 0.050.
A composition according to claim 1 or 2, comprising from 6 to 28 wt-%, more preferably from 7 to 26 wt-%, even more preferably from 8 to 24 wt-%, still more preferably from 9 to 22 wt-%, still more preferably from 10 to 20 wt-% and yet more preferably from 12 to 18 wt-% of the one or more surfactants.
A cleaning composition according to any one of claims 1 to 3, wherein the one or more detergent surfactants are selected from one or more of anionic surfactants, cationic surfactants, non-ionic surfactants, amphoteric surfactants and zwitterionic surfactants.
A cleaning composition according to any one of claims 1 to 4 comprising from 0.2 to 1.0 wt-% of the defibrillated primary cell wall material.