rheological properties of cosmetic compositions containing rosemary ...

Kamelia Petkova-Parlapanska, Verginia Nancheva, Svetlomir Diankov, Journal of Chemical Technology and Metallurgy, 49, 5,Ivaylo 2014, Hinkov, 487-493Maria Karsheva

RHEOLOGICAL PROPERTIES OF COSMETIC COMPOSITIONS CONTAINING ROSEMARY AND GRAPEFRUIT PULP AND SEEDS EXTRACTS Kamelia Petkova-Parlapanska, Verginia Nancheva, Svetlomir Diankov, Ivaylo Hinkov, Maria Karsheva University of Chemical Technology and Metallurgy 8 Kl. Ohridski, 1756 Sofia, Bulgaria E-mail: [email protected]

Received 10 October 2013 Accepted 04 July 2014

ABSTRACT Modern cosmetic formulations represent a combination of synthetic and natural ingredients. Knowledge of the rheological behavior allows managing the structure and the quality of the products by means of supplement addition, regime change or mechanical and technological processing adjustment. The extraction from rosemary and grapefruit pulp and seeds with ethanol-in-water solutions is carried out in a thermostated shaker at 20ºС. The total polyphenol content (TPC) and the antioxidant capacity (AOC) of the extracts are determined. The cosmetic compositions prepared are based on stearic acid, with 3-ethanolamine as emulsifier. Extracts are used as a preservative, instead of controversial lately methyl-parabens. The rheological behavior of the cosmetic formulations is studied. It is found that all compositions exhibited thixotropic flow behavior. The cosmetic emulsion containing an alcoholic extract of grapefruit seeds has different rheological behavior which may be described by the Bingham rheological model. This effect can be explained by the composition of the extract and its influence on the pH. It is found that the extract from grapefruit seeds has acidic properties and affects the pH of the medium. The cosmetic formulation with rosemary extract exhibits power low and thixotropic behavior. The purity of the cosmetic formulations was tested against E. Coli bacteria. It is found that no bacterial colonies are observed neither after one day, nor after three months of storage. It can be concluded that the natural extracts from rosemary and grapefruit seeds and pulp exhibit good antibacterial properties, being quite satisfactory substitute of the parabens. Keywords: extraction, total polyphenols, antioxidant capacity, cosmetic composition, rheology.

INTRODUCTION The modern cosmetic products provide some necessary substances to the skin and also protect it from the harmful influence of various external factors. Recently the use of natural ingredients like plant extracts, essential oils, organic acids, etc. in cosmetic’s production becomes even more popular. A lot of the customers are looking for parabens free cosmetics based on natural extracts. The client’s evaluation is essential for the developing of new and/or the improvement of already embedded in manufacture products. There are many references to assess the perception of cosmetic products. Some of them offer rheology as a suitable tool for determining

the sensory qualities [1, 2]. The investigation of the rheological and mechanical properties of the cosmetic compositions is important for the process design: transport, mixing, and packing. They are highly influenced by the above mentioned properties. This information is helpful for quality control and stability control at storage conditions. Such parameters as viscosity and structure are also essential for the approval of the cosmetic products from the customers. The rosemary (Rosmarinus Officinalis L.) contains a lot of phenolic acids: rosmarinic, carnosic, caffeic, ursolic, betulinic and other chemical compounds as camphor, rosmaridiphenol and rosmanol that engender the antibacterial and fungicidal properties of the alco-

487

Journal of Chemical Technology and Metallurgy, 49, 5, 2014

holic extracts [3]. The extract from grapefruit seed and pulp is prepared in ratio 1:4, the solvent being 70 % vol. ethanol-in-water solution. Previous studies proved that flavonoids, ascorbic acid, citric acid, sterols and minerals are present in the extracts which also have antibacterial and fungicidal properties [4]. The aim of this work is to investigate the possibility to use the plant extracts with high antioxidant capacity instead of methylparaben as preservative in cosmetic compositions and to follow the rheological behavior of the formulations obtained in dependence of their composition. EXPERIMENTAL Materials and methods Rosemary was purchased from “Bioset”, 2012. Grapefruit was supplied from the local market. The mass of the samples was measured by Sartorius Analitic balance (precision 0.1 mg). The extraction process was carried out in a Gyrotory water bath shaker, model 676, New Brunswick Scientific, Edison N.J., USA. The separation of the solid and the liquid phase after the extraction was made by a Büchner funnel vacuum filtration. For the determination of total content of polyphenols (TPC) and antioxidant capacity (AOC) were used Folin-Ciocalteu reagent (Sigma, 2N solution), gallic acid (Sigma), dehydrated Na2CO3 (Valerus), ethanol (96 %, Valerus), DPPH● (Sigma), methanol (99.9 % LabScan) and distilled water. The other supplementary chemicals and reagents are acquired from Sigma–Aldrich. Analysis of the extracts Total polyphenols are determined spectrophotometrically by the Folin–Ciocalteu method [5] using gallic acid as a standard for the calibration line. Doublebeam UV-VIS-spectrophotometer (S-22 UV/vis, Boeco, Germany) was used to analyze the samples. Light absorption was measured at 765 nm [6]. In order to avoid accidental errors, each analysis was carried out at least three times. The results are presented as g gallic acid equivalent (GAE) per 1 L extract. The antioxidant capacity (AOC) is determined using DPPH● method because of its simplicity and stable results. This assay evaluates the capacity of an extract to neutralize free radicals of DPPH● solution. The light absorbance was measured at 517 nm [7]. The free radical

488

inhibition capacity IC was calculated by the expression:

I=

( A0 − AS ) A0

× 100, % (1)

where Ao is absorption of the blank sample, AS is absorption of the extract containing sample [8]. A mechanical stirrer OSD-20, Boeco, Germany was used for the preparation of the cosmetic creams. For the rheological measurements a rotational viscometer with co-axial cylinders with S1 cylinder Rheotest RV2 (Germany) was used. Unique experiments with S2 cylinder showed no wall slip effect of the products studied. For all compositions the up and down flow curves are followed at ambient temperature to check the formulations for thixotropy. Samples’ preparation The dry rosemary was sieved and the fraction 0.5 to 1 mm was used for the experiments. The raw material (1g) was mixed in a beaker (volume 150 mL) with 70 % vol. ethanol-in-water solution (10 mL), and placed in a previously thermostated shaker (beginning of the extraction process). The samples are taken regularly (10, 20, 30, 40, 60, 90 min) and separated via Büchner funnel vacuum filtration and then analysed. The filtration time (about 30 s) is taken into consideration. The grapefruit seeds and pulp were dried at 55°С in a drier (Ditherm, Robotika, Bulgaria) and then grinded. After that 1 g was mixed in a beaker with 70 % vol. ethanol-in-water solution (10 mL), and placed in a previously thermostated shaker. Three different runs were carried out at 24, 36 and 48 h. Cosmetic emulsions’ preparation The extracts with the highest polyphenols’ content and antioxidant capacity are chosen for the preparation of the cosmetic emulsions. As a base is used stearic acid and triethanolamine as an emulsifier. 1 mL of each extract is added to the mixture instead of methylparaben as a preservative together with 1 g of sodium benzoate. The compositions of the cosmetic formulations studied are presented in Tables 1 and 2. The stearic acid is liquefied in a water bath at temperature of 70°C together with the other component, the glycerin, at low stirring speed (50 min-1). When the mixture becomes a homogeneous liquid the components of the water phase (distilled water, plant extract, trietha-

Kamelia Petkova-Parlapanska, Verginia Nancheva, Svetlomir Diankov, Ivaylo Hinkov, Maria Karsheva

Table 1. Cosmetic formulations A.

Emulsion composition, % mass Stearic acid Glycerol Distilled water Sodium hydroxide Rosemary extract Grapefruit seeds and pulp extract Sodium benzoate Fragrance

A1

A2

A3

14 10 72 3

14 10 71 3 1

14 10 71 3 1

1 0.2

Table 2. Cosmetic formulations B. Emulsion composition, B1 % mass. Stearic acid 10 Glycerol 10 Distilled water 77.5 Thriethanolamine 0.5 (emulsifier) Rosemary extract Grapefruit seeds and pulp extract Sodium benzoate 2 Fragrance 0.2

1 0.2

1 0.2

B2

B3

10 10 76.5 0.5

10 10 76.5 0.5

1 1 2 0.2

2 0.2

nolamine, sodium benzoate, fragrance, also previously tempered) are added. In order to obtain a homogeneous emulsion the temperature is slowly decreased to an ambient at stirring speed 700-800 min-1 [9]. As a result a tender white creamy formulation is obtained. To check it up the cosmetic formulation stability it is left for 3 months. Its rheological and antimicrobial properties against the E.coli are studied at the beginning and at the end of the storage period. The cosmetic compositions are left at ambient temperature without using sterile storage conditions. The microbiologic studies were carried out by an inoculation of the microorganisms on agar medium, then adding of the formulation studied and following the development of the microbial colonies in the cosmetic formulations. RESULTS AND DISCUSSION Determination of total polyphenols’ content in the extracts In Fig. 1 the kinetics of TPC of the rosemary extracts is presented.

Fig. 1. Total polyphenols’ content v/s time of the rosemary extracts.

An initial increase of TPC can be seen in Fig. 1. After the 60th min of the extraction the measured values become almost constant. So, it can be concluded that for the operational conditions studied the plateau is reached and there is no economic reason to continue the process further. The values of the total polyphenols’ content for the extracts from grapefruit pulp and seeds after 24, 36 and 48 hours are presented in Fig. 2. The process is studied till 48 hours. It can be seen in the Fig. 2 that TPC increases with the time. Determination of the antioxidant capacity in the extracts The comparison of the AOC of the rosemary extracts is presented in Fig. 3. The highest values of AOC, similar for the TPC, are obtained after 60th min. The continuation of the process till 90th min does not lead to significant changes. For this reason the extract from the 60th min is used for the preparation of the cosmetic formulations.

Fig. 2. TPC evolution in time for the extracts of grapefruit pulp and seeds.

489


Fig. 3. Antioxidant capacity of the rosemary extracts.

Fig. 5a. Flow curves – A compositions: ∆ - A1 (base); ◊ A2 (rosemary); ■ – A3 (grapefruit).

Fig. 4. Antioxidant capacity of the grapefruit pulp and seeds’ extracts: ◊ - 24 h; ∆ - 36 h; □ - 48 h.

Fig. 5b. Flow curves – B compositions: ∆ - B1 (base); ■ – B2 (rosemary); ◊ - B3 (grapefruit).

The comparison of the AOC of the grapefruit pulp and seeds’ extracts is presented in Fig. 4. It is obvious from Fig. 4 that the results for AOC obtained after 36 and 48 h coincide. In the cosmetic formulations the 48th h extract is used because of its higher total polyphenols’ content.

them is the flow curve of the basic formulation. On the contrary, for B formulations, the highest flow curve is that of the formulation with rosemary extract, the lowest one - that with the grapefruit extract. As in the first case, the basic composition is situated between them. Such behavior could be explained with differences in the composition and in their pH values. From the sensory perception point of view, the formulations of series B are softer and tender, these of series A are harder and not so pleasant for application. For further studies, the B formulations were chosen. In Figs. 6 - 8 typical flow curves for the formulations studied are presented. With black points are given the upward curves, with the hollow ones - the downward. It can be seen that the flow curves pattern of the basic composition and the one with rosemary extract are curvilinear without yield stress (Figs. 6, 7). So their rheological behavior can be described by power law rheological model - equation (2). The formulation with grapefruit pulp and seeds’ extract (Fig. 8) exhibits yield

Rheological measurements In Figs. 5a and 5b the flow curves of the formulations A and B are presented. There are differences in their compositions as shown in Tables 1 and 2 (A formulations contain sodium hydroxide, B formulations contain - triethanolamine as emulsifier, 4 % less stearic acid, 4 % more distilled water). The Figs. 5 a, b show that all the flow curves of A formulations are curvilinear without yield stress, so, their rheological behavior can be described with power-law rheological model. The flow curve of the rosemarycontaining formulation is the lowest one; the highest is that of the grapefruit extract containing one. Between

490


Fig. 8. Typical flow curves of the compositions studied – composition with grapefruit pulp and seeds extract B3.

Fig. 6. Typical flow curves of the compositions studied – basic composition B1.

leaved at maximal rotation speed of the system (1320 s-1) till obtaining the constant value of the shear stress. Then the shear stress values are followed in downward order. The most commonly used for description the rheological behavior are the models of Ostwald de Waele (eq. 2), Herschell- Bulkley (eq. 3) and Bingham (eq. 4) [10, 11, 12]:

τ = Kγ n

τ = τ 0 + Kγ n

(2) (3)

Fig. 7. Typical flow curves of the compositions studied – composition with rosemary extract B2.

τ = τ 0 + µ p γ

stress, but it is linear, so the Bingham rheological model is proper for its description. It is also evident that all the formulations exhibit thixotropy due to the presence of the stearic acid in the compositions. The down flow curve is the equilibrium one. It is obtained as follows: after the obtaining of the up flow curve, the sample is

Here τ is the shear stress, Pa, γ is the shear rate, s-1, τ 0 is the yield stress, Pa, K is the consistency index, Pa sn, n is the flow index, determining the degree of the non-Newtonian behavior, µ p is the plastic viscosity in the Bingham rheological model, Pa.s. Taking into account that the rheological models are

(4)

Table 3. Rheological parameters of the cosmetic formulations studied.

No

Composition τ 0 , Pa K , Pa.s

n,−

R2

Mean error, %

pH

n

1

A1

0

3.325

0.496

0.989

5.22

7

2

A2

0

7.397

0.409

0.934

11.58

5

3

A3

0

15.465

0.273

0,954

5.73

6

4

B1

0

5.881

0.340

0.982

6.19

4.5

5

B2

0

12.544

0.266

0.984

4.00

5

6

B3

3.5575

0.010

1

0.995

3.08

4

7

B4

0

1.015

0.346

0.882

11.65

4

491


Table 4. Rheological parameters of the B series cosmetic formulations for up and down curve.

No composition τ 0 , Pa (up)

K , Pa.s n (up)

n,− (up)

τ 0 , Pa (down)

K , Pa.s n (down)

n,− (down)

1

B1

0

5.881

0.340

0

5.078

0.262

2

B2

0

12.544

0.266

0

6.233

0.357

3

B3

3.558

0.010

1

2.087

0.004

1

not physical laws but mathematical description of the flow behavior of the samples, the choice of the model is often determined by the accuracy of the description and the model simplicity. The values of the rheological parameters were found statistically using the MS Excel 2013® statistical package. In Table 3 the values of the rheological parameters and the model accuracy are presented. For the composition B3 both the power-law and the Bingham rheological models were fitted. From Table 3 it is evident, that the Bingham model gives much higher accuracy than the power-law one. The different type of the flow behavior of the samples containing grapefruit extract can be explained with the extract pH values and with its composition (Table 3). It can be seen that the pH values of the composition with Bingham plastic behavior are the lowest one, compared to other samples studied.

The rheological parameters for up and down flow curves are presented in Table 4. The extracts with the highest polyphenols’ content and antioxidant capacity were chosen for the preparation of the cosmetic emulsions. A tender white creamy formulation is obtained. The cosmetic compositions are shown in Fig. 9. The “paraben-free” compositions possess the main characteristics of the commercial beauty creams: agreeable perfume and pearl nuance. They absorb easily in the skin without greasy stains after usage. They are stable (without sedimentation or cremation) during 3 months of storage period. We can conclude that the natural extracts from grapefruit seeds and pulp and rosemary demonstrate good antibacterial properties, being quite satisfactory substitute of the parabens. Microbiologic studies The purity of the cosmetic formulations was tested against E. Coli bacteria. The microorganisms were inoculated in agar medium and the evolution of the colonies in time was followed. It was found that no bacterial colonies can be observed neither after one day, nor after three months of storage period. CONCLUSIONS

Fig. 9. Cosmetic compositions.

492

Cosmetic compositions based on stearic acid were formulated. The parabens in the conventional recipe were replaced by natural extracts from rosemary and grapefruit seeds and pulp. A high antioxidant capacity and total polyphenols content were measured for both materials. The ethanol-in-water solutions were applied as extracting agent. For the cosmetic formulations the extracts with optimal values of total polyphenols content


and antioxidant capacity were chosen. The rheological behavior of the cosmetic compositions obtained was studied. It was found that all they are non-Newtonian. The compositions containing the rosemary extract are pseudo-plastic and thixotropic, those with the extract of grapefruit pulp and seeds - Bingham plastic and thixotropic. The difference in the rheological behavior can be explained by the difference in the extracts and their pH values. The parameters of the rheological models were determined statistically. For the formulations, the stability and the antimicrobial activity were studied. It was found that no bacterial colonies can be observed neither after one day, nor after three months of storage period. We can conclude that the natural extracts from rosemary and grapefruit seeds and pulp exhibit good antibacterial properties, being quite satisfactory substitute of the parabens. Acknowledgements This work is partially supported financially by the Research Division of the University of Chemical Technology and Metallurgy, Sofia, contract № 11278/2014. REFERENCES 1. A. Sgarbossa, F. Lenci, E. Bergamini, R. Bizzarri, B. Cerbai, F. Signori, Z. Gori, M. Dolichol, A solar filter with UV-absorbing properties which can be photoenhanced, Biogerontology, 6, 2003, 379 - 385. 2. D. Dimitrov, Theory of cosmetic formulations, Novatiym, Plovdiv, 2003, (in Bulgarian). 3. M. Razboršek, D. Vončina, V. Doleček, E. Vončina, Determination of Major Phenolic Acids Phenolic

Diterpenes and Triterpenes in Rosemary (Rosmarinus officinalis L.) by Gas Chromatography and Mass Spectrometry, Acta Chim. Slov., 54, 2007, 60 - 67. 4. Z. Cvetnid, S. Vladimir-Kneževid, Antimicrobial activity of grapefruit seed and pulp ethanolic extract, Acta Pharm., 54, 2004, 243 - 250. 5. J. Peñarrieta, J. Alvaradoa, B. Bergenståhlc, B. Åkessonb, Spectrophotometric Methods for the Measurement of Total Phenolic Compounds and Total Flavonoids in Foods, Bolivian Journal of Chemistry (Revista Boliviana de Química), 24, 2007, 5 - 9. 6. A. Bucić-Kojić, M. Planinića, M. Tomasa, M. Bilića, D. Velića, Study of solid–liquid extraction kinetics of total polyphenols from grape seeds, Journal of Food Engineering, 81, 1, 2007, 236 - 242. 7. W. Brand-Williams, M. E. Cuvelier, C. Berset, Use of free radical method to evaluate antioxidant activity, Lebensmittel Wissenschaft und Technologie, 28, 1995, 25 - 30. 8. R. J Moore, C. Frankton, The Cirsium arizonum complex of the southwestern, Canadian Journal of Botany, 52, 1974, 543 - 551. 9. J. Lakovska, L. Draganov, M. Kasarova, B. Peneva, Manual for practical exercises in Pharmaceutical Technology, 1, Sofia, 1999, (in Bulgarian). 10. O. Harzallah, D. Dupuis, Rheological properties of TiO2 particles in polymer solutions, Reol.Acta, 42, 2003. 11. Z.P. Shulman, V.I. Baikov, Rheodynamics heat and mass transfer in film flows, Science and Technology, Minsk, 1979, (in Russian). 12. H. A. Barnes, J. E. Hutton, K. Walters, An introduction to rheology, S.l.: Elsevier Science Publishers, 1989.

493