CLIAMS:1. An improved method for assessing slipperiness of soap bar, the method comprising:
a) preparing a soap noodle composition by mixing the ingredients for 1-10 minutes preferably 3-8 minutes and more preferably 6-7 minutes to ensure homogenized mixing and applying shear force to calculate slipperiness of the obtained product,
b) milling the mixture obtained in step a) for 1- 15 minutes preferably 4-10 minutes and most preferably 5-7 minutes and applying shear force to calculate slipperiness of the obtained product,
c) plodding the entire mixture obtained in step b) for 30-70 minutes, preferably 50-60 minutes applying shear force to calculate the slipperiness of the obtained product, and
d) stamping individual bar out of the soap mass;
such that the shear force at each step provides optimum slipperiness of the soap bar obtained thereof.
2. The method as claimed in claim 1, wherein said shear force is in the range of 0.70 -2.50Kgf.
3. The method as claimed in claim 2, wherein said shear force range is in the range of 1.72 to 2.25 Kgf.
4. The method as claimed in claim 1, wherein the slipperiness of the soap achieved is 8. Or more in scale of 1- 10 score.
5. The method as claimed in claim 1, wherein said soap noodle composition comprising
a. 70-85 % by weight of Soap,
b. 0.5-4 % by weight of glycerine,
c. 0.5-6% by weight of AOS,
d. 0.5-3.5% by weight of SLES,
e. 6-16% by weight of water; and
f. 0-5% by weight of additives.
6. The method as claimed in claim 5, wherein said additives are selected from color, fragrance, and preservatives.
,TagSPECI:Field of the invention

The present invention relates to method for assessing slipperiness of soap. More particularly the invention relates to a method for assessing the slipperiness of soap during manufacturing stages.

Background and the prior art
Slipperiness of toilet soap bar is essential characteristic which is very important parameter for both bar physical behavior (bar aesthetic) and in use functional properties of the bar for consumers. These properties are evaluated by consumers based on bar glide on skin and smoothness of bar during application.

Conventionally slipperiness of soap bar is also termed as bar smoothness, bar glide on skin in sensory evaluations and is evaluated by panelist using sensory scoring method. So the sensory evaluation is subjective to individual panelist. Often the results derived are inconclusive.

WO2009078857 assigned to Colgate Palmolive describes smoothness of soap bar by panelist sensory evaluation test. However it does not explain quantitative method for evaluation of smoothness during process formulations.

Further fine tuning of formulation for desired quality of final product to improve bar smoothness / slipperiness is very difficult in the present context where method is not established to characterize the same.

Further the sensory evaluation method can be conducted only on finished product and cannot be done during manufacturing process stages. Therefore repetitive trials of the formulation need to be conducted to achieve desired smoothness characteristics of the soap bar.

Hence there is a need to develop a method which helps to monitor bar smoothness/ slipperiness characteristics during amalgamation of raw materials or during processing stage to manufacture soaps.

Objects of the invention
It is an object of present invention to overcome the drawbacks of prior art.
It is another object of present invention to provide a method to monitor the slipperiness of soap bar.
It is yet another object of present invention to provide a method of monitoring bar smoothness/ slipperiness characteristics during intermediate manufacturing stages.

Summary of the invention
According to one aspect of the present invention there is provided an improved method for assessing slipperiness of soap bar is provided comprising the steps of:
a) preparing a soap noodle composition by mixing the ingredients for 1-10 minutes preferably 3-8 minutes and more preferably 6-7 minutes to ensure homogenized mixing and applying shear force to calculate slipperiness of the obtained product,
b) milling the mixture obtained in step a) for 1-15 minutes preferably 4-10 minutes and most preferably 5-7 minutes and applying shear force to calculate slipperiness of the obtained product,
c) plodding the entire mixture obtained in step b) for 30-70 minutes, preferably 50-60 minutes applying shear force to calculate the slipperiness of the obtained product, and
d) stamping individual bar out of the soap mass;
such that the shear force at each step provides optimum slipperiness of the soap bar obtained thereof.

Brief description of Accompanying Drawings
Figure 1 illustrates batching Process with conventional sensory method
Figure 2 illustrates batching process with New Proposed Instrumental Method

Detailed description of invention
The present invention relates to method of quantification of slipperiness of soap bar by analyzing soap mass during manufacturing at different stages of process i.e. amalgamation, milling and extrusion using shear force analysis instrument.

It has been surprisingly found that method of shear force analysis for soap bar provides cost effective, faster evaluation of bar slipperiness and also provide method to predict bar slipperiness during process which helps in predicting required amount of plasticizers (e.g., (soap, glycerin, SLES, water, AOS, PEG, Fatty Alcohols etc) to improvise bar properties (e.g. in use bar glide & smooth feel of bar on skin).

The present method allows to measure elasticity behavior of soap preferably in ribbon shape to predict soap bar slipperiness. This method helps to monitor the characteristics of slipperiness of soap bar at soap manufacturing stage and helps to fine tune the formulation to get desired bar property (bar slipperiness of finished soap bar) at any intermediate stages .

The present inventors surprisingly found that slipperiness of bar is directly related with shear force of solid materials like soap or soap noodles. Thus higher the shear force value, higher the bar slipperiness.

Thus according to the present invention, an improved method for monitoring slipperiness of soap bar is provided comprising the steps of:
a) preparing a soap noodle composition by mixing the ingredients for 1-10 minutes preferably 3-8 minutes and more preferably 6-7 minutes to ensure homogenized mixing and applying shear force to calculate slipperiness of the obtained product,
b) milling the mixture obtained in step a) for 1- 15 minutes preferably 4-10 minutes and most preferably 5-7 minutes and applying shear force to calculate slipperiness of the obtained product,
c) plodding the entire mixture obtained in step b) for 30-70 minutes, preferably 50-60 minutes applying shear force to calculate the slipperiness of the obtained product, and
d) bar stamping
such that the shear force at each step provides optimum slipperiness of the soap bar obtained thereof.

It is critical to ensure proper mixing before sample subjected for test method as per present invention. The instrumental method of present invention for bar slipperiness evaluation by shear force characteristics determination is carried out using shear force value of soap preferably in ribbon form. The soap mass essentially is a solid material and subjected to shear force using tensile tester machine. The shear force range as applied for present method ranges from 0.7-2.5 Kgf, preferably in the range of 1.72 to 2.25 Kgf.

Shear force is a measurement parameter and it is measured under constant load and speed using Tensile Tester Instrument. The average slipperiness of soap mass at every operational steps (mixing, milling, plodding and stamping) is more than 8 in scale of 1 to 10 wherein 1 is very rough and 10 is very slippery as shown in table 3.

Figure 1 demonstrates that sensory evaluation method is limited to apply only when final bar is produced and cannot be conducted for in process stage materials. Thereby for evaluating slipperiness of soap, bar needs to be made as final bar to evaluate whether desired characteristics are achieved or not. After sensory evaluation if it is found that bar slipperiness is not as per desired, the produced soap need to be discarded and fresh batch need to be taken with alteration in formulation.

Figure 2 shows that slipperiness of soap bar can be measured at every stage of soap bar processing. Thereby as per present invention it is surprisingly found that shear force measurement method for bar evaluation avoids multiple trials of soap bar making process.
In accordance with the present invention, the soap noodle composition comprises
a. 70-85 % by weight of Soap,
b. 0.5-4 % by weight of glycerine,
c. 0.5-6% by weight of AOS,
d. 0.5-3.5% by weight of SLES,
e. 6-16% by weight of water; and
f. 0-5% by weight of additives.
The additives are selected from color, fragrance and preservatives. Colouring agents, fragrances and preservatives which are commonly known in the art for use in cosmetic composition are suitable to use in the present invention.

The present invention is more advantageous over conventional sensory method as present method can be used at every stage of batch making of soap and rectification can be done during batching which translate to raw material saving (positive impact on cost). The present method also requires less number of trials to achieve optimum slipperiness as the same batch can be rectified. Thus the present method saves time and energy whereas in sensorial method used in prior art, sample can only be tested after completion of batch which translates to more risk of batch rejection/raw material wastage, time consuming and less energy efficient.

The invention is now illustrated by way of non limiting examples. Soap bars as given herein examples are made in the batch size of, but not limited to 0.5–1 tonne.

Example 1
Preparation of composition
Table 1
Ingredients (%) SM08A SM07A
Soap 70-85 70-95
Water 6-16 4-15
Glycerine 0.5-4 0-1
AOS 0.5-6 0-1
SLES 0.5-3.5 0-1
Other Additives (color, fragrance, preservatives etc.) 0-5 0-5

SM07A is made using SM07 soap noodles having shear force value 0.67Kgf whereas soap prototype SM08A is made using special noodles SM08 having higher shear force values i.e. 0.72 Kgf. Soap are evaluated for Slipperiness characteristics of soap.

Example 2
Specific formulation (working example)
Table 2
Ingredients (%) SM08A SM07A
Soap 79 90
Water 12 9
Glycerine 2 0
AOS 3 0
SLES 3 0
Other Additives (color, fragrance, preservatives etc.) 1 1

Example 3
Method for shear force analysis
1. Sample preparation
Ribbons of test samples (soap noodles, soap bar) were made using Roll Mill (Double roll, Triple roll etc) or by using any other mechanism like pressing device to create sheets like structure.
2. Measurement
· Test samples ribbon was placed in cutting probe, parameters like test speed were adjusted and instrument was started. Test speed is maintained at about 12inch/min with constant load of 500N. Calibration is done using standard weights for load cell calibration.
· Instrument was run through till ribbon broke down.
Speed was maintained at 12 inch/min (speed was constant throughout out measurement) and applied weight is 500N (constant for all the test samples)
Shear force was measured to evaluate the bar slipperiness

Example 4
Method for Sensory Evaluation (prior art)
Ø Panels were asked to use the soap and score the mentioned properties in 1-10 score (Low to High)
Ø In one example, soap prototype SM07A was made using soap noodles SM07 with shear force value of 0.67Kgf with the following sensory characteristics.
Ø In other example, soap noodles SM08A shows improved value of shear force value of 0.72Kgf due to additional ingredient of Glycerin (1-5%), AOS (1-8%), SLES (1-6%) and increased moisture (1-10%). When soap are made using improved soap noodles SM08, the resultant soap (SM08A) shows improved bar Slipperiness characteristics

Results-
When soap was made using soap noodles SM 07 and evaluated by sensory panelist, it shows lesser score for bar Slipperiness compare to soap prototype SM 08A. When soap was made using improved soap noodles SM 08 and evaluated by sensory panelist, it shows higher score for bar Slipperiness compared to soap prototype SM 07A. It was observed that soap made using improved soap mass of higher shear value have improved bar Slipperiness characteristics. The results are shown in table 3.
Table 3
Method Parameter Soap SM08 A Soap SM07 A
Conventional Method -Sensory Evaluation Scores Bar Glide 8.5 7.5
Bar smooth feel 8.0 7.4
Slipperiness of Bar* 8.5 7.3
Present method Shear Force 0.72Kgf 0.67Kgf

*Higher the values, better the bar slipperiness

In example given herein shows that soap SM 07 has lower shear force value of 0.67 than that of SM 08 which has shear force value of 0.72. It was observed that SM 08 was rated higher score for bar Slipperiness compared to that of soap prototype SM 07A. It was observed that soap with higher shear value have improved bar Slipperiness characteristics.
The above comparison in table 3 shows that the properties such as bar glide, bar smooth feel and slipperiness of bar is higher when shear force is applied on soap mass composition SM08A. This method also predicts bar slipperiness during process which helps in predicting required amount of Plasticizers (e.g., (soap, glycerin, SLES, water, AOS, PEG, Fatty Alcohols etc) to improvise bar properties (e.g. in use bar glide & smooth feel of bar on skin.)

Example 5-Comparison of present method during manufacturing stages and conventional method of prior art
Table-4
Processing Stage? Mixing Milling Plodding & Recycling Bar Stamping
Time Required for each step (Average timing for soap making)? 6-7mins 5-7mins 50-60mins 1bar/30secs
Method for Slipperiness/Plasticity?
Conventional Method-Sensory N N N Y
Present Method –Shear Force Y Y Y Y

Y –Slipperiness/Plasticity of bar can be measured at this stage
N-Slipperiness/Plasticity of bar cannot be measured at this stage

Sample which is essentially required for sensory evaluation is finished bar soap made after stamping of soap mass to soap bar (Fig 1). Table 4 also explains that after every processing stage such as mixing, milling and plodding final soap bar are not made hence sensory evaluation cannot be done whereas sensory evaluation is possible only after bar stamping stage.

Table-5

Testing Method Raw Material (RM) Cost Energy Efficiency Cost Saving Time Savings
Sensory Evaluation of prior art More loss as batch repeatability chances are more(RM loss20%) Less Efficient. Required more energy, more repetitions expected ~ higher process cost~ higher cost for trained panels (for every evaluative) More time taking (Testing can only be done once batch is completed)
Present Method Rectifications can be done during intermediate stage process, so less chance of batch repetition(Max expected loss 5%) Process efficiency is ~95%.As major rectifications can be done milling stage, minimum chances of repeatability Instrument cost (only once time investment) More time efficient (testing can be done any stage of processing. No need to wait till batch over)
Observation:
It is evident from tables 4 and 5 that measurement of Shear force to quantify the bar plasticity is more advantageous over conventional sensory method as present method can be used at every stage of batch making of soap and rectification can be done during batching which translate to raw material saving (positive impact on cost). The present method also requires less number of trials to achieve optimum slipperiness as the same batch can be rectified. Thus the present method saves time and energy whereas in sensorial method used in prior art, sample can only be tested after completion of batch which translates to more risk of batch rejection/raw material wastage, time consuming and less energy efficient.

The present method is also advantageous in predicting bar slipperiness/plasticity during batching will help in saving time up to around 1 hrs compare to conventional sensory method.