Method for analysing a chocolate

Abstract

Provided is a method of analysing a chocolate, the method comprising measuring the coefficient of friction of at least two of: a first mixture comprising from 70 wt% to 85 wt% of the chocolate and from 15 wt% to 30 wt% of a liquid; a second chocolate mixture comprising from 60 wt% to 69 wt% of the chocolate and from 31 wt% to 40 wt% of the liquid; and a third chocolate mixture comprising from 41 wt% to 59 wt% of the chocolate and from 41 to 59 wt% of the liquid. The method finds utility in evaluating the sensory properties of a chocolate sample.

Description

[0001] Method for analysing a chocolate

[0002] Field of the invention

[0003] The present invention relates to a method for analysing a chocolate. More particularly, the invention relates to a method of measuring the coefficient of friction of at least two mixtures of the chocolate and a liquid.

[0004] Background to the invention

[0005] The ‘mouthfeel’ of a food refers to the physical sensations in the mouth caused by the food and forms a part of a consumer’s eating experience. Receptors in the tongue, the teeth and other parts of the mouth help create the overall impression of mouthfeel. Mouthfeel is not a constant; the mouthfeel of a food will change as the consumer chews and mixes their food with saliva. Mouthfeel is also highly subjective; this makes it difficult and expensive to collect reliable and consistent data from human panels.

[0006] Chocolate is a food for which mouthfeel is a critical property. Chocolates are highly complex systems, typically containing cocoa solids, cocoa butter, other fats (vegetable and milk), milk solids (protein and lactose), sugars (e.g. sucrose), emulsifiers and flavourings. The ratios of these components affect the microstructure of the chocolate and how it transforms in the mouth. Because of this, small changes in the composition of a chocolate product can result in a significant variation in its overall sensorial properties such as, hardness, melting rate, taste, aroma and flavour. Consumer perception is extremely sensitive for this food type. This means that even extremely small changes in a chocolate’s properties can be easily noticed by consumers. Some properties of chocolates that consumers commonly perceive are mouthcoating, astringency, creaminess, mellowness, chewiness, smoothness, adhesiveness, and how the chocolate lingers.

[0007] As a consumer eats a chocolate they heat it to body temperature, causing the fat to melt, and mix with saliva. This forms an oil-in-water emulsion microstructure in the mouth which has unique lubricating properties and fat droplet sizes. Because these emulsions are constantly changing, the effect of oral processing on a chocolate’s friction is very difficult to study or model.

[0008] It is desirable to be able to evaluate the sensory properties of chocolate in a repeatable way so as to enable an understanding of the mouthfeel of the food. The present invention has been devised with these issues in mind.

[0009] Summary of the invention

[0010] A first aspect of the invention provides a method of analysing a chocolate, the method comprising measuring the coefficient of friction of at least two of: i. a first mixture comprising from 70 wt% to 85 wt% of the chocolate and from 15 wt% to 30 wt% of a liquid; ii. a second chocolate mixture comprising from 60 wt% to 69 wt% of the chocolate and from 31 wt% to 40 wt% of the liquid; and

[0011] Hi. a third chocolate mixture comprising from 41 wt% to 59 wt% of the chocolate and from 41 to 59 wt% of the liquid.

[0012] In some embodiments, the coefficient of friction is measured using a tribometer.

[0013] Tribology devices (tribometers) measure the friction between a first surface and a second surface. When a lubricating material is added to the device, the friction between the two surfaces is reduced, and as more lubricant is added the friction will decrease until a full layer of lubricant is present between the surfaces. Tribology has been used as a tool to analyse certain properties of foods such as creaminess, smoothness and slipperiness. However, the adoption of tribology as a technique has been slow due to a lack of proper techniques and understanding concerning the oral processing of foods.

[0014] In some embodiments the tribometer comprises a sliding surface. In some embodiments the coefficient of friction is measured as a function of speed (e.g. sliding speed).

[0015] Examples of suitable tribometers for carrying out the invention include pin-on-disc, ring-on- ring, block-on-ring, ball-on-disc, ball(s)-on-plate, ball-on-three-plate and twin-disc tribometers. Preferably, the tribometer is a ball-on-disc tribometer. The ball-on-disc tribometer may comprise a ball, a disc and a pot.

[0016] As a skilled person would know, a ball-on-disc tribometer measures the coefficient of friction between the disc and the ball. The disc is connected to a motor that is configured to spin the disc. The ball is connected to a rod that is free to rotate. The ball can be lowered onto to the disc to contact and optionally exert a pressure on the disc. During operation, if the ball is pressed on the disc the friction force will rotate the ball, and the rod. The speed of rotation of the rod can be recorded. The speed of rotation of the rod correlates to the friction force between the ball and the disc. In a ball-on-disc tribometer the disc is located inside a pot. The pot is capable of holding a liquid so that the surface of the disc is coated in the liquid. During operation, if the liquid is present, it may affect the friction between the ball and the disc.

[0017] In some embodiments, the first mixture comprises or consists of from 72 wt% to 80 wt% of the chocolate and from 20 wt% to 28 wt% of the liquid, or from 74 to 78 wt% of the chocolate and from 22 to 26 wt% of the liquid.

[0018] In some embodiments, the first mixture consists of 75 wt% of the chocolate and 25 wt% of the liquid.

[0019] Advantageously the present inventors have observed that a first mixture consisting of 75 wt% chocolate or less results in no visible clumping of the chocolate mixture. This was discovered by viewing the mixture. Any clumping in the mixture may make the subsequent friction measurements less stable and repeatable.

[0020] In some embodiments, the second mixture comprises or consists of from 62 wt% to 68 wt% of the chocolate and from 32 wt% to 38 wt% of the liquid, or from 64 wt% to 67 wt% of the chocolate and from 33 wt% to 36 wt% of the liquid.

[0021] In some embodiments, the second mixture consists of 67 wt% of the chocolate and 33 wt% of the liquid.

[0022] In some embodiments, the third mixture comprises or consists of from 44 wt% to 55 wt% of the chocolate and from 45 wt% to 55 wt% of the liquid, or from 47 wt% to 52 wt% of the chocolate and from 48 wt% to 53 wt% of the liquid.

[0023] In some embodiments, the third mixture consists of 50 wt% of the chocolate and 50 wt% of the liquid.

[0024] It will be appreciated that the relative amounts of the chocolate and the liquid in the first, second or third mixture may alternatively be expressed as a ratio. Thus, in some embodiments, the first mixture comprises or consists of the chocolate and the liquid at a ratio of from 2.5 to 4 chocolate : 1 liquid, or from 2.8 to 3.5 chocolate : 1 liquid.

[0025] In some embodiments, the first mixture comprises or consists of the chocolate and the liquid at a ratio of 3 chocolate : 1 liquid. In some embodiments, the second mixture comprises or consists of the chocolate and the liquid at a ratio of from 1 .5 to 2.4 chocolate : 1 liquid, or from 1 .8 to 2.2 chocolate : liquid.

[0026] In some embodiments, the second mixture consists of the chocolate and the liquid at a ratio of 2 chocolate : 1 liquid.

[0027] In some embodiments, the third mixture comprises or consists of the chocolate and the liquid at a ratio of from 0.5 to 1.4 chocolate : 1 liquid, or from 0.7 to 1.2 chocolate : 1 liquid.

[0028] In some embodiments, the third mixture consists of the chocolate and the liquid in a 1 :1 ratio.

[0029] In some embodiments, the first mixture consists of the chocolate and the liquid at a ratio of 3 chocolate : 1 liquid, the second mixture consists of the chocolate and the liquid at a ratio of 2 chocolate : 1 liquid, and the third mixture consists of the chocolate and the liquid at a ratio of 1 chocolate : 1 liquid.

[0030] In some embodiments, the method comprises measuring the coefficient of friction of the first mixture and the second mixture.

[0031] In some embodiments, the method comprises measuring the coefficient of friction of the first mixture and the third mixture.

[0032] In some embodiments, the method comprises measuring the coefficient of friction of the second mixture and the third mixture.

[0033] In some embodiments, the method comprises measuring the coefficient of friction of the first mixture, the second mixture and the third mixture.

[0034] Advantageously, the present inventors have found that by measuring the coefficient of friction of at least two, preferably all three, of the first, second and third mixtures, more useful information on the sensory properties of a chocolate can be obtained than has previously been possible. Comparing different dilutions gives more information about the status of a bolus that is normally evaluated by a consumer during eating, thereby better reflecting the sensory perception. In particular, the method of the invention enables the properties of different chocolates to be more clearly differentiated while maintaining reproducibility of the data for a particular chocolate sample. In some embodiments, the method further comprises measuring the coefficient of friction of the chocolate in the absence of the liquid.

[0035] The method may further comprise adding the chocolate to the pot of the tribometer, prior to measuring the coefficient of friction.

[0036] It will be appreciated that the chocolate must be in a liquid or semi-liquid state in order for the coefficient of friction to be measured. Therefore, in some embodiments the method comprises adding molten chocolate to the pot of the tribometer, prior to measuring the coefficient of friction.

[0037] In some embodiments, the chocolate is at a temperature of from 35°C to 50°C, e.g. about 40°C.

[0038] The term 'chocolate' in the context of the present invention is not restricted by the various definitions of chocolate provided by government and regulatory bodies. A 'chocolate' may be a dark chocolate, a milk chocolate, a white chocolate or a compound chocolate. Chocolate comprises at least one fat. The fat may be cocoa butter, butterfat, a cocoa butter equivalent (CBE), a cocoa butter substitute (CBS) (sometimes known as a cocoa butter replacer, CBR) or any combination of the above. In a particular embodiment, the chocolate comprises cocoa butter.

[0039] CBEs are defined in Directive 2000 / 36 / EC. CBEs include illipe, Borneo tallow, tengkawang, palm oil, sal, shea, kokum gurgi and mango kernel. CBE's are usually used in combination with cocoa butter.

[0040] CBS's include CBS laurics and CBS non-laurics. CBS laurics are short-chain fatty acid glycerides. Their physical properties vary but they all have triglyceride configurations that make them compatible with cocoa butter. CBS's include those based on palm kernel oil and coconut oil. CBS non-laurics consist of fractions obtained from hydrogenated oils.

[0041] In some embodiments, the chocolate is a milk chocolate, a dark chocolate, a white chocolate or a compound chocolate.

[0042] In some embodiments, the method further comprises mixing the chocolate with the liquid to form the first, second and / or third mixture, prior to measuring the coefficient of friction. The mixing may conveniently be carried out in the pot of the tribometer. In some embodiments, during mixing the load force (e.g. the load force of the ball of a ball-on- disc tribometer) is from 0 N to 1 N. In some embodiments, the load force is 0.5 N or less, or 0.2 N or less. In a preferred embodiment the load force is 0 N. The load force is the force that is applied to a sliding surface of a tribometer (e.g. a disc). For example, wherein the tribometer is a ball-on-disc tribometer, the load force refers to the force of the ball on the disc.

[0043] In some embodiments, during mixing the sliding surface (e.g. disc) has a speed of from 400 mm / s to 4000 mm / s, from 500 mm / s to 3000 mm / s, or from 1000 mm / s to 2500 mm / s (e.g. about 2000 mm / s).

[0044] In some embodiments the chocolate is mixed with the liquid for at least 5 seconds, at least 10 seconds, at least 15 seconds or at least 20 seconds.

[0045] In some embodiments, during mixing the load force (e.g. of the ball) is from 0 N to 1 N, and the sliding surface (e.g. disc) has a speed of from 400 mm / s to 4000 mm / s. In some embodiments, during mixing the load force is 0 N and the sliding surface has a speed of about 2000 mm / s.

[0046] Without wishing to be bound by theory, it is believed that the mixing speed, mixing duration, and load force applied during mixing according to the invention accurately simulates the oral processing stages of a human mouth.

[0047] The mixtures of the invention comprise the structural components of emulsions, solids, and crystals. These structural components affect the measured coefficient of friction. Overmixing during a mixing step can lead to a mixture that is highly homogenous. Measurements taken using an overmixed mixture may provide less information that is relevant to the chocolate’s properties during oral processing. It is therefore desirable to avoid overmixing the chocolate and the liquid. On the other hand, undermixing during a mixing step can lead to a mixture that is highly heterogenous. Measurements of the coefficient of friction taken using an undermixed mixture may be irregular and / or not reproducible. It is therefore desirable to avoid undermixing chocolate and the liquid.

[0048] In some embodiments, the coefficient of friction is measured over a range of sliding speeds. In some embodiments, the range of sliding speeds has an initial sliding speed of from 1 mm / s to 10 mm / s and a final sliding speed of from 100 mm / s to 600 mm / s.

[0049] In some embodiments, the initial sliding speed is from 1 to 7 mm / s, e.g. 5 mm / s.

[0050] In some embodiments the final sliding speed is from 300 mm / s to 500 m / s, e.g. 400 mm / s.

[0051] In some embodiments the range of sliding speeds has an initial sliding speed of 5 mm / s and a final sliding speed of 400 mm / s.

[0052] In some embodiments, the sliding speed is increased over a period of time of 120 seconds or less, 90 seconds or less, 60 seconds or less.

[0053] In some embodiments, during measuring the load force (e.g. the load force of the ball) is from 1 N to 5 N, from 2 to 4 N, e.g. 3 N.

[0054] In some embodiments, the method further comprises discarding the first, second and / or third mixture (e.g. from the pot of the tribometer) and subsequently measuring the coefficient of friction of any remaining residue (e.g. residue remaining on the sliding surface such as the disc).

[0055] In some embodiments, discarding the mixture comprises draining or pouring the mixture from the tribometer (e.g. from the pot of the tribometer). In some embodiments, after discarding the mixture, the drained surfaces of the tribometer (e.g. the sliding surface such as a disc, the ball and the pot) are wiped (e.g. with a paper towel). Without being bound by theory, it is believed that after measuring the friction coefficients of the first, second and / or third mixtures, surface active material may be left on or absorbed onto the surface of the tribometer. This may provide valuable information for understanding sensory attributes such as lingering, mouthcoating and drying. Therefore, discarding the mixture from the tribometer to leave a residue (such as, a residue on the sliding surface) simulates the residual coating on the tongue and palate after swallowing.

[0056] In some embodiments, the method comprises the steps of:

[0057] (a) measuring the coefficient of friction of the first mixture;

[0058] (b) adding a quantity of the liquid to the first mixture and mixing so as to form the second mixture;

[0059] (c) measuring the coefficient of friction of the second mixture; (d) adding a further quantity of the liquid to the second mixture and mixing so as to form the third mixture;

[0060] (e) measuring the coefficient of friction of the third mixture.

[0061] In some embodiments, the method further comprises, prior to step (a): measuring the coefficient of friction of the chocolate in the absence of the liquid; and adding an initial quantity of the liquid to the chocolate and mixing so as to form the first mixture.

[0062] In some embodiments, the method further comprises, after step (e): discarding the third mixture (e.g. from the pot of the tribometer); and measuring the coefficient of friction of any remaining residue (e.g. residue remaining on the sliding surface such as a disc).

[0063] Thus, conveniently the first, second and / or third mixtures can be prepared in situ (e.g. in a pot of the tribometer), prior to measuring their coefficients of friction. The method of the invention enables the coefficients of friction of all three mixtures, as well as that of the pure chocolate (i.e. in the absence of the liquid) and the residue, to be measured in a single experiment.

[0064] It will be appreciated that, in order to measure the coefficient of friction of the mixtures, the chocolate must be maintained in a molten or semi-molten state. This may be achieved by adding warm or hot liquid to form the first, second and third mixtures.

[0065] Thus, in some embodiments, the liquid (e.g. when added to form the first, second and / or third temperature) is at a temperature of from 35 to 50 e.g. about 40°C.

[0066] The chocolate is mixed with a liquid in order to mimic the effect of chocolate being mixed with saliva in the mouth during eating.

[0067] In some embodiments, the liquid is selected from water, saline, human saliva and artificial saliva.

[0068] In some embodiments, the liquid is an artificial saliva, wherein the artificial saliva comprises water and at least one of:

[0069] (i) a salt (e.g. Potassium chloride, Magnesium chloride, Calcium chloride, Sodium chloride, potassium phosphate, or sodium fluoride); (ii) a thickener (e.g. carboxymethyl cellulose, glycerin, sorbitol, hydroxypropylmethylcellulose, or methyl cellulose); and

[0070] (iii) an enzyme (e.g. Amylase, ptyalin, glucose oxidase, or lactoferrin).

[0071] In some embodiments the liquid is water.

[0072] In some embodiments, the sliding surface (e.g. disc) is designed to replicate the texture of a human tongue.

[0073] The sliding surface may be formed from a polymer. The polymer may be an elastomer, a thermoplastic elastomer, a rubber, a nitrile butadiene rubber, a plastic, a silicone, or a synthetic resin. In some embodiments, the sliding surface is made from is polydimethylsiloxane (PDMS).

[0074] The ball may be formed from a polymer or a metal (e.g. steel or aluminium). The polymer may be an elastomer, a thermoplastic elastomer, a rubber, a nitrile butadiene rubber, a silicone, or a synthetic resin. In some embodiments, the ball is made from is polydimethylsiloxane (PDMS). The ball may have a substantially smooth surface, or it may be textured.

[0075] For example, a suitable sliding surface (e.g. disc) may be formed from the tongue mimicking surface described by Andablo-Reye et al., ACS Applied Materials & Interfaces, Volume 12, Issue 44, November 4, 2020, 49277-50202.

[0076] In some embodiments the sliding surface (e.g. disc) comprises artificial fungiform and / or artificial filiform. The mean density of the artificial fungiform may be from 1 1 to 15 per 10'4m2(e.g. about 13.5 per 104m2). The mean density of the artificial filiform may be from 130 to 190 per 10'4m2(e.g. about 160 per 104m2).

[0077] In some embodiments, the coefficient of friction of the first mixture, the second mixture, the third mixture, the chocolate in the absence of the liquid and / or the remaining residue on the sliding surface (e.g. disc) is measured more than once.

[0078] In some embodiments, the coefficient of friction is measured from 2 to 6 times. In a preferred embodiment, the coefficient of friction is measured three times.

[0079] In some embodiments, the method further comprises correlating a measured coefficient of friction with at least one sensory attribute of a chocolate. In some embodiments, the at least one sensory attribute (also referred to herein as “sensory property”) is thickness, mouthcoating, powdery, smoothness, adhesive, chewy, and / or lingering.

[0080] The methods of the invention may conveniently be used to evaluate prototype products.

[0081] Thus, in a further aspect, there is provided a method of evaluating one or more sensory properties of a chocolate sample, the method comprising:

[0082] (a) analysing the chocolate sample using a method as described herein, so as to measure the coefficients of friction of at least two of a first, a second and a third mixture; and

[0083] (b) using the measured coefficients of friction, determining whether the chocolate sample has one or more desired sensory properties.

[0084] In some embodiments, step (b) comprises comparing the measured coefficients of friction with reference values. The reference values may be coefficients of friction obtained using the methods described herein for a reference chocolate composition.

[0085] It will be appreciated that the coefficients of friction measured using mixtures of the chocolate sample should be compared with coefficients of friction obtained for corresponding mixtures of the reference composition. For example, in step (a) the coefficients of friction may be measured for (i) a first mixture comprising from 70 wt% to 85 wt% of the chocolate sample and from 15 wt% to 30 wt% of a liquid, and (ii) a second mixture comprising from 60 wt% to 69 wt% of the chocolate sample and from 31 wt% to 40 wt% of the liquid. In step (b), the measured coefficients of friction are then compared with reference values which are the coefficients of friction of first and second mixtures of the reference chocolate composition.

[0086] In some embodiments, the reference chocolate composition is an existing product (e.g. a product on the market).

[0087] In some embodiments, the measured coefficients of friction are compared with reference values obtained for at least two reference chocolate compositions. For example, a new product may be formulated to be smoother than existing product A and at least as adhesive as existing product B. In this case, the measured friction coefficients of a prototype chocolate sample may be compared with those obtained for products A and B. Optionally, the method further comprises changing the composition of the chocolate sample and / or the process used to make the chocolate sample in order to achieve the desired sensory properties of the chocolate composition.

[0088] The invention thus provides a convenient way to formulate chocolate compositions. Advantageously, the evaluation of new compositions can be carried out much more rapidly using tribology than by human sensory analysis panels.

[0089] Embodiments of the invention will now be described by way of example and with reference to the accompanying figures in which:

[0090] Figure 1 is an image of a sliding surface (a disc) having a tongue mimicking surface of the type that may be used in the method of the invention;

[0091] Figure 2 is an image of a ball-on-disc tribometer containing molten chocolate;

[0092] Figure 3 is a macro image of a tongue mimicking surface showing dome shaped 0.3 mm high “fungiform papilla”;

[0093] Figure 4 is a macro image of a tongue mimicking surface showing flat top 0.1 mm high “filiform papilla”;

[0094] Figures 5a to 5h are graphs showing the friction coefficient measured over a range of speeds for 7g samples of three different chocolates (574, 874, 924) having been mixed with different amounts of water;

[0095] Figure 6 is a graph showing the average friction coefficient of each of the mixtures described in Figures 5a to 5h;

[0096] Figure 7 shows the average friction coefficient of two chocolate / water mixtures obtained by mixing 7g samples of the chocolate and water at different speeds;

[0097] Figure 8 shows the average friction coefficient of four chocolate / water mixtures obtained by mixing 7g samples of two different chocolates and water at different speeds;

[0098] Figure 9 shows the measured friction coefficient for 10 undiluted chocolate samples;

[0099] Figure 10 shows the measured friction coefficient for 10 mixtures comprising 75% chocolate and 25% water;

[0100] Figure 1 1 shows the measured friction coefficient for 10 mixtures comprising 66% chocolate and 33% water;

[0101] Figure 12 shows the measured friction coefficient for 10 mixtures comprising 50% chocolate and 50% water;

[0102] Figure 13 shows the measured friction coefficient of drained discs after containing 10 mixtures comprising 50% chocolate and 50% water mixtures; and

[0103] Figure 14 shows the average friction coefficients for each chocolate at each dilution as shown in Figures 9-10 for the range of 5-100 mm / s. Example 1 : Measuring friction coefficients

[0104] The friction coefficient of chocolate samples was measured using a 50 Duro PDMS (3 / 4”) ball and a textured PDMS disc. Starting with 7 g of chocolate, the friction coefficient was measured using the “Stribeck 1” measurement conditions shown in Table 1 . After measurement, 1 gram of water was added to the chocolate and mixed according to either the fast or slow mixing steps shown in Table 1. The friction coefficient of the mixture was measured using the same “Stribeck 1 ” measurement conditions. This process was repeated until a mixture of 7 grams of water and 7 grams of chocolate had been prepared and the friction coefficient thereof measured. The mixing speed was determined by visually inspecting the resultant mixture. When the mixture had been mixed to the point that the mixture appeared homogenous, mixing was stopped to prevent over mixing.

[0105] Table 1

[0106] Slide / roll ratio is the ratio of the sliding and rolling speed calculated as follows: SRR =,Ja Ub- where Uaand Ubare the linear speeds of body a and b respectively.

[0107] The measured friction coefficients are shown in Figures 5 to 8.

[0108] Example 2: Measuring the tribological properties of a chocolate

[0109] Materials and methods

[0110] Equipment:

[0111] • Tribometer: MTM (Mini-Traction Machine) (PCS instruments)

[0112] • Balls: 50 Duro PDMS(Polydimethylsiloxane)

[0113] • Surface: tongue mimicking surface made of PDMS(Polydimethylsiloxane) The tongue mimicking PDMS disc was made in a custom-made mould. One surface of the mould had a negative texture to mimic the surface features of the tongue. The disc was formed by using a Sylguard™ 184 as follows:

[0114] • Mix Sylguard™ 184 at a ratio of 1 :10 (curing agent: base)

[0115] • Degas in a vacuum

[0116] • Add into the mould in excess

[0117] • Degas

[0118] • Place into oven at 50 °C for 6 hours.

[0119] Testing protocols:

[0120] 1 . 10 g of molten chocolate (40°C) was added into the tribometer sample pot.

[0121] 2. The coefficient of friction of the chocolate was measured using a speed range of 5- 400 mm / s and a ball load force of 3 N. This measurement was repeated three times.

[0122] 3. 3.3 ml of water (40°C) was added to the chocolate. This diluted the chocolate, resulting in a 3:1 (75% chocolate) chocolate : water mixture (i.e. a first mixture). This mixture was then mixed for 20 seconds. During mixing, the ball was raised to a height of 1 mm above the sliding surface to apply a 0 N ball force and the sliding surface was moved at a speed of 2000 mm / s.

[0123] 4. The coefficient of friction of the 3:1 (75%) chocolate mixture was measured using a speed range of 5-400 mm / s and a ball load force of 3 N. This measurement was repeated three times.

[0124] 5. 1.7 ml of water (40°C) was added to the 3: 1 (75%) chocolate mixture. This further diluted the chocolate, resulting in a 2:1 (66.66%) chocolate : water mixture (i.e. a second mixture). This mixture was then mixed for 20 seconds. During mixing, the ball was raised to a height of 1 mm above the sliding surface to apply a 0 N ball force and the sliding surface was moved at a speed of 2000 mm / s.

[0125] 6. The coefficient of friction of the 2:1 (66.66%) chocolate mixture was measured using a speed range of 5-400 mm / s and a ball load force of 3N. This measurement was repeated three times.

[0126] 7. 5.0 ml of water (40°C) was added to the 2:1 (66.66%) chocolate mixture. This further diluted the chocolate, resulting in a 1 :1 (50%) chocolate : water mixture (i.e. a third mixture). This mixture was then mixed for 20 seconds. During mixing, the ball was raised to a height of 1 mm above the sliding surface to apply a 0 N ball force and the sliding surface was moved at a speed of 2000 mm / s. 8. The coefficient of friction of the 1 :1 (50%) chocolate mixture was measured using a speed range of 5-400 mm / s and a ball load force of 3 N. This measurement was repeated three times.

[0127] 9. The sample in the tribometer sample pot was discarded.

[0128] 10. The coefficient of friction of the 1 :1 (50%) chocolate mixture residue was measured using a speed range of 5-400 mm / s and a ball load force of 3 N. This measurement was repeated three times.

[0129] Results

[0130] 10 chocolate samples were tested and their coefficient of frictions were recorded. The coefficients of friction were recorded for the pure chocolate (Figure 9), a 75 / 25 bolus (Figure 10), a 66 / 33 bolus (Figure 11), a 50 / 50 bolus (Figure 12), and the drained surface (Figure 13). An average coefficient of friction was calculated for the speed range of 10-100 mm / s for each chocolate (Figure 14). These results are shown in Table 2:

[0131] Table 2

[0132] Example 3 Quantitative Descriptive Analysis (QDA®)

[0133] Quantitative Descriptive Analysis (QDA®) of chocolate samples was conducted according to industry standard methods (Chapter 8, Quantitative Descriptive Analysis, Joel L. Sidel, Rebecca N. Bleibaum and K.W. Clara Tao in Descriptive Analysis in Sensory Evaluation, First Edition. Edited by Sarah E. Kemp, Joanne Hort and Tracey Hollowood.© 2018 John Wiley & Sons Ltd. Published 2018 by John Wiley & Sons Ltd).

[0134] Line scales were employed for panel training and data collection. The line scale is designed as 6-inch in length with sensory intensities word anchors located 0.5 inch from each end. The scale direction goes from left to right with increasing intensities, e g., slightly to very. During data collection, panelists measured sensory intensities independently at individual booth without reference served as intensities standards. Panelists were allowed to use different parts of the scale to determine the sensory intensities by themselves.

[0135] The samples were assessed in triplicate for their aroma, appearance, texture, mouthfeel, flavour and aftertaste. The results were collected via the Compusense® data capture system and were analysed with QDA® software (Tragon®) using Analysis of variance (ANOVA). The Duncan minimum significant difference was calculated in order to determine those samples which were significantly different (p<0.05).

[0136] The average scores for chocolate attributes from the QDA are shown in Table 3:

[0137]

[0138] Example 4: Correlation of QDA results and measured coefficients of friction

[0139] Results from a QDA® are known to be informative for multiple statistical analysis methods. The QDA® results of the invention may be analysed using any industry standard methods, such as the ones described in Lawless HT., Heymann H. 2010. Sensory Evaluation of Food: principles and practices, 2nd edition. New York, NY. Chapman &Hall; Press.

[0140] Results from a quantitative descriptive analysis and results from a tribological assessment were correlated using the following formula:

[0141] Wherein x and y are the mean of the values of the coefficient of friction and the QDA scores, and Xi are the values of the coefficient of friction and the QDA scores.

[0142] The correlation coefficients for the QDA of example 3 (Table 3) and the coefficient of frictions of example 2 (Table 2) are shown in Table 4.

[0143] Table 4

[0144] Values marked with * represent moderate correlation. Values marked with t represent strong correlation.

[0145] A correlation was found for the sensory attributes linked to the lubrication properties of the chocolates and boluses in sliding contact: thickness, mouthcoating, powdery, smoothness, adhesiveness, and lingering. No correlation was found for sensory attributes linked more strongly to different material properties and motions: e.g. chewy. In particular, mouthcoating, powdery, smooth, and adhesive were strongly correlated with the measured coefficients of friction. Correlation of tribological data to sensory attributes allows significantly faster testing and development of chocolates that have desirable properties while removing the need for a human panel for sensory analysis.

Claims

Claims1 . A method of analysing a chocolate, the method comprising measuring the coefficient of friction of at least two of: i. a first mixture comprising from 70 wt% to 85 wt% of the chocolate and from 15 wt% to 30 wt% of a liquid; ii. a second chocolate mixture comprising from 60 wt% to 69 wt% of the chocolate and from 31 wt% to 40 wt% of the liquid; and iii. a third chocolate mixture comprising from 41 wt% to 59 wt% of the chocolate and from 41 to 59 wt% of the liquid.

2. The method of claim 1 , wherein the coefficient of friction is measured using a tribometer.

3. The method of claim 1 or claim 2, wherein the method comprises measuring the coefficient of friction of the first mixture and the second mixture.

4. The method of any one of claims 1 to 3, wherein the method comprises measuring the coefficient of friction of the first mixture, the second mixture and the third mixture.

5. The method of any one of claims 1 to 4, further comprising measuring the coefficient of friction of the chocolate in the absence of the liquid.

6. The method of any one of claims 2 to 5, wherein the tribometer comprises a sliding surface and the coefficient of friction is measured as a function of sliding speed.

7. The method of claim 6, wherein the sliding surface is designed to replicate the texture of a human tongue, optionally wherein the sliding surface is made from polydimethylsiloxane (PDMS).

8. The method of any of claim 6 or claim 7, wherein the coefficient of friction is measured over a range of sliding speeds, optionally wherein the range of sliding speeds has an initial sliding speed of from 1 mm / s to 10 mm / s and a final sliding speed of from 100 mm / s to 600 mm / s, further optionally wherein the sliding speed is increased over a period of time of 120 seconds or less.

9. The method of any preceding claim, wherein the method further comprises discarding the first, second and / or third mixture and subsequently measuring the coefficient of friction of any remaining residue.

10. The method of any one of claims 2 to 9, wherein the tribometer is a ball-on-disc tribometer comprising a ball, a disc and a pot.1 1 . The method of claim 10, wherein the method further comprises mixing the chocolate with the liquid in the pot to form the first, second and / or third mixture, prior to measuring the coefficient of friction.

12. The method of claim 1 1 , wherein during mixing the load force of the ball is from 0 N to 1 N, and the disc has a speed of from 400 mm / s to 4000 mm / s.

13. The method of any one of claims 10 to 12, wherein the ball is made from an elastomer, optionally the elastomer is polydimethylsiloxane (PDMS).

14. The method of any one of claims 11 to 14, wherein during measuring the load force of the ball is from 1 N to 5 N.

15. The method of any preceding claim, comprising the steps of:(a) measuring the coefficient of friction of the first mixture;(b) adding a quantity of the liquid to the first mixture and mixing so as to form the second mixture;(c) measuring the coefficient of friction of the second mixture;(d) adding a further quantity of the liquid to the second mixture and mixing so as to form the third mixture;(e) measuring the coefficient of friction of the third mixture, optionally wherein the method further comprises:(i) prior to step (a), measuring the coefficient of friction of the chocolate in the absence of the liquid; and adding an initial quantity of the liquid to the chocolate and mixing so as to form the first mixture; and / or(ii) after step (e), discarding the third mixture; and measuring the coefficient of friction of any remaining residue.

16. The method of any preceding claim, wherein the chocolate is at a temperature of from 35°C to 50°C.

17. The method of any preceding claim, wherein the liquid is water.

18. The method of any preceding claim, wherein the coefficient of friction of the first mixture, the second mixture, the third mixture, the chocolate in the absence of the liquid and / or the remaining residue (e.g. on the sliding surface or disc) is measured more than once, optionally wherein the coefficient of friction is measured three times.

19. The method of any preceding claim, further comprising correlating a measured coefficient of friction with a sensory attribute of a chocolate, optionally wherein the sensory attribute is thickness, mouthcoating, powdery, smoothness, adhesive, chewy, and / or lingering.

20. A method of evaluating one or more sensory properties of a chocolate sample, the method comprising:(a) analysing the chocolate sample using a method as described in any one of claims 1 to 19, so as to measure the coefficients of friction of at least two of a first, a second and a third mixture; and(b) using the measured coefficients of friction, determining whether the chocolate sample has one or more desired sensory properties.

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