Issue 44 — July 2008

Issue 44
Category		Title		Authors
Cover Picture		Performance of Cupuassu Products on Hair Care Applications		Ana Carolina Santos Nogueira, Henrique Jorge Sousa Sales, Hans-Martin Haake

Abstract

Cupuassu (Theobroma grandiflorum) has been used by the cosmetic industry in both hair and skin care formulations. The main claims of hair products using Cupuassu are improved hydration, softness, shine and combability. The aim of this study was to evaluate the performance of Cupuassu-based raw materials on hair cosmetic products using hydro-retention, tensile strength and gloss measurements. Our results show that Cupuassu Butter has a remarkable effect on hair hydro-retention, comparable to that obtained with Shea Butter. The positive effects of Cupuassu products were also seen on the mechanical properties of hair. The breaking tensile strength of bleached hair fibers treated with Cupuassu Butter increased by 30% in average, compared to untreated bleached hair. No significant gloss results were obtained in hair treated with Cupuassu products.



Introduction

These days there is a general trend to consume natural products. Consumers tend to turn to nature to feel happy with their bodies. The increase of the natural food market is a good example of this. Generally speaking, health and wellness are associated with natural products. On the other hand, overwhelmed by the endless number of products launched on the market, consumers tend to question the real efficacy of these products.

Cupuassu (Theobroma grandiflorum) is a tree native of south and southeastern Amazonia. The fruit contains oleaginous seeds embedded in a white pulp that is very similar to the cacao [1, 2]. The seeds constitute about 16% of the fruit's dry weight and have a fat content of about 60%. This similarity to cacao has been extensively explored by the food industry to produce chocolates, ice creams and fruit drinks [3].

Human hair is composed of keratin, a group of insoluble, cystine-containing helicoidal protein complexes, which form 65% to 95% of the hair by weight. The cortex makes up the majority of the hair shaft, responsible for the mechanical properties of hair. The melanin granules (about 3% by weight), or hair pigments, are located inside the cortex. Surrounding the cortex is the cuticle, a protective layer of overlapping, keratinized scales, which can account for up to 10% of the hair fiber by weight [4, 5].

It is well known that exposure to common cosmetic procedures, such as combing, washing and bleaching, damage hair fiber. In addition to the current trend to consume natural products and the global interest in Amazon products, Cupuassu has also been explored by the cosmetic industry in hair care applications, using claims such as improved hydration, softness, shine and combability. Deposition of oils on hair has been claimed to have a beneficial protective effect. Oil based hair conditioners are believed to help prevent moisture loss from hair, which causes dryness and loss of elasticity. For full beneficial effect, oil penetration throughout the cortex is desirable, as it can improve the hair's mechanical properties. However, the moisture retention effect of oil is dominated by surface deposited oil [6]. Therefore, to support claims such as hydro-retention and improvement of mechanical properties, the oil should present good deposition on hair surface as well as the capacity to penetrate the hair cortex.

Materials and Methods

Hair samples: Tresses of virgin dark-brown hair (De Meo Brothers Inc.), each one weighing 2.0 g and approximately 30-cm in length, were initially washed with a 2.0 % Sodium Laureth Sulfate solution. The following procedure was used: (a) hand-washing with 1 mL of the solution for 1 min; (b) rinsing with tap water for 1 min; (c) wet combing using a polypropylene comb. This treatment was applied twice on each hair sample, which was then dried at room temperature, combed and stored in a plastic bag prior to treatment. This procedure was carried out to standardize the samples before initiating the proposed treatment. Gloves were used throughout all the procedures.

Bleaching treatment: The hair tresses were bleached using the "Blondor" product (Wella). The bleaching treatment was performed according to the label instructions. The samples were in contact with the product for 30 minutes; they were then thoroughly rinsed, combed and dried in an air-conditioned room (25° C and 60% RH) for 24 h.

Cupuassu treatment: Three cupuassu products (Cognis Brasil Ltda.) were used in this study: Cupuassu Butter, Cupuassu Hydrophilized Butter and Cupuassu Betain. Cupuassu Butter is obtained from the Amazon forest in partnership with local community groups. The first two products are mainly sold as emollients. The last one has shown good results in performance tests where it replaces Cocoamidopropyl Betain. To evaluate the performance of these products on hair, they were incorporated into shampoo and leave-on conditioner formulations, which are shown in Tables I and II, respectively. In all formulations, we opted to use small concentrations of Cupuassu products, since this better represents our market requirements.

In order to verify the effect of Cupuassu Butter on hair properties, the bleached hair tresses were treated with formulations shown in Table II. Shea Butter was used as a comparison parameter, since it is used worldwide in hair care products. In a second experiment, we verified the effect of Cupuassu Hydrophilized Butter and Cupuassu Betain on hair. The bleached tresses were treated with formulations shown in Table I and subsequently a leave-on formulation containing 3% of Cupuassu Butter (FN6) was applied on each hair tress.

The rinse-off formulations (Table I) were applied using the following procedure: (a) hand-washing with 1 mL of the formulation for 3 min; (b) rinsing with tap water for 1 min; (c) wet combing using a polypropylene comb; (d) drying in an air-conditioned room for 24 h, prior to the leave-on application. The leave-on formulations (Table II) were applied on each tress with gloved hands, uniformly distributed from root to tip ends. 0.2 g formulation/g hair was applied on each hair tress and triplicate hair tresses were used in each experiment.

Hydro-retention measurements: The hair hydro-retention provided by the different treatments was quantified by gravimetric measurements. After 24h conditioning, each hair tress was weighed. Subsequently each one was immerged in 100 mL of distilled water for 1.0 h; the excess water was eliminated using a towel and each tress was weighed again to calculate the adsorbed water. After the leave-on applications, each tress was weighed again (t=0h) and left drying in the conditioned room. After successive times (1.0; 2.0; 3.0 and 4.0h), the tresses were weighed. The subtraction of hair mass weighed at each successive time from the hair mass obtained at t=0h is the mass of water lost by the hair tresses. The results of the experiment are presented as percentage of hair hydro-retention, which is calculated subtracting the values of mass of water lost from the values of adsorbed water for each hair tress and rationing this result by the values of adsorbed water.

Table I: Shampoo formulation (placebo + four shampoo formulations) proposals.



Table II: Leave-on conditioner formulations (placebo + three leave-on formulations) proposals.



Tensile Strength measurements: Stress/strain curves were obtained from 40 fibers (5.0 cm length, 1 h conditioning at 25° C and 100 % RH) of each sample using a universal test machine (EMIC Ltda.) with a 10 N load cell operating at 10 mm/min constant speed. The diameter of each fiber was measured after conditioning using a micrometer (Mitutoyo Ltd.).

Gloss measurements: Hair gloss values were obtained using a statistical gloss meter (Rhopoint Ltd.). An incident angle of 85° and a support especially designed for hair tresses were used in the experiments. Hair tresses were aligned from root to tip end and tied near the root end. Triplicate hair tresses were used in the experiments. Ten gloss measurements were performed on each tress. Gloves were used throughout all the procedures.

Results

Effects on Hair Hydro-retention:

The hydro-retention measurements were carried out to evaluate the ability of different products to slow down the water exchange between hair and ambient moisture.

Figure 1: Hydro-retention provided by different leave-on conditioners formulations on hair fibers: Placebo (FN0'), Formulation containing 1% Cupuassu Butter (FN5), Formulation containing 3% Cupuassu Butter (FN6) and Formulation containing 1% Shea Butter (FN7). Control is Bleached Tress only. The values are the average of triplicate hair samples.

Figure 1 shows the hydro-retention provided by different leave-on formulations. All formulations cause a decrease in moisture loss, including the Placebo Formulation (FN0'). This is expected and justified by a film forming effect on the hair fibers. We also observe that this effect is more pronounced with formulations containing the butters (except Formulation Number 5, which shows results similar to the Placebo Formulation). Additionally, the hydro-retention provided by Cupuassu Butter is a dose-dependent effect, increasing when higher doses are incorporated in the formulation. The effect of the formulations is observed up to four hours after application. At this time, the control hair contains about 10% of its initial adsorbed water. Hair treated with FN0' and FN5 contains about 30% of its initial adsorbed water, while hair treated with FN6 and FN7 contains circa 40%.

Figure 2: Hydro-retention provided by different shampoos plus a leave-on conditioner formulation on hair fibers: Placebo (FN0), Formulation containing 3% Cocoamidopropyl Betain (FN1), Formulation containing 3% Cupuassu Betain (FN2), Formulation containing 3% Cocoamidopropyl Betain plus 3% Hydrophilyzed Cupuassu Butter (FN3), Formulation containing 3% Cupuassu Betain plus 3% Hydrophilyzed Cupuassu Butter (FN4) and Formulation containing 3% Cupuassu Butter (FN6). Control is Bleached Tress only. The values are the average of triplicate hair samples.

Figure 2 shows hydro-retention results obtained with hair containing different pre-treatments and treated with the leave-on formulation containing 3% of Cupuassu Butter (FN6). We observe that the hydro-retention results are coherent with those shown in Figure 1 for hair treated with FN6 only, and that the pretreatment does not prevent hair moisture loss.

Effects on Hair Mechanical Properties:

The Tensile Strength measurements were carried out to verify the effect of different products on hair mechanical properties, correlating these effects with the diffusion capacity of each product into hair fiber.

Figure 3: Breaking Tensile Strength data obtained for hair treated with different leave-on conditioner formulations: Placebo (FN0'), Formulation containing 1% Cupuassu Butter (FN5), Formulation containing 3% Cupuassu Butter (FN6) and Formulation containing 1% Shea Butter (FN7). Control is Bleached Tress only. Virgin hair is untreated. Box-plots were obtained from 40 hair fiber measurements from each hair sample.

Figure 3 shows Breaking Tensile Strength results for hair treated with the leave-on conditioners. As expected, breaking tensile strength is lower for bleached hair compared to untreated hair. Hair treated with the Placebo Formulation presents results similar to bleached hair. Hair treated with Formulation Number 7 shows tensile strength results more similar to untreated hair, indicating that Shea Butter improves damaged hair's resistance to break. Hair treated with Cupuassu Butter (FN5 and FN6) shows higher tensile strength values than bleached or untreated hair, presenting better improvement in hair tensile strength than hair treated with Shea Butter. Increasing the Cupuassu Butter concentration from 1% to 3% in the formulation does not increase the tensile strength, but does diminish the variability of the results.

Figure 4: Breaking Tensile Strength data obtained for hair treated with different shampoos plus a leave-on formulation: Formulation containing 3% Cocoamidopropyl Betain (FN1), Formulation containing 3% Cupuassu Betain (FN2), Formulation containing 3% Cocoamidopropyl Betain plus 3% Hydrophilyzed Cupuassu Butter (FN3) ,Formulation containing 3% Cupuassu Betain plus 3% Hydrophilyzed Cupuassu Butter (FN4) and Formulation containing 3% Cupuassu Butter (FN6). Control is Bleached Tress only. Virgin hair is untreated. Box-plots were obtained from 40 hair fiber measurements from each hair sample.

Figure 4 shows Tensile Strength results for hair pretreated with shampoo formulations plus a leave-on containing 3% of Cupuassu Butter. Hair treated with formulations containing Cocoamidopropyl Betain or Cupuassu Betain plus Cupuassu Hydrophilized Butter (FN3 and FN4) shows breaking tensile strength higher than the control hair and similar to hair treated only with Cupuassu butter, indicating that this pretreatment does not improve breaking hair tensile-strength values.

Figure 5: Breaking Elongation data obtained for hair treated with different leave-on conditioner formulations: Placebo (FN0'), Formulation containing 1% Cupuassu Butter (FN5), Formulation containing 3% Cupuassu Butter (FN6) and Formulation containing 1% Shea Butter (FN7). Control is Bleached Tress only. Virgin hair is untreated. Box-plots were obtained from 40 hair fiber measurements from each hair sample.

Figure 5 shows Breaking Elongation results for hair treated with the leave-on conditioners. Bleached hair shows higher breaking elongation values than untreated hair, indicative of fiber degradation. Treatment with Shea or Cupuassu Butter does not reduce this damage. On the other hand, in Figure 6, we observe that hair pretreated with Formulations 3 and 4 present breaking elongation values similar to untreated hair, indicating a benefit of pre-treatment.

Figure 6: Breaking Elongation data obtained for hair treated with different shampoos plus a leave-on formulation: Formulation containing 3% Cocoamidopropyl Betain (FN1), Formulation containing 3% Cupuassu Betain (FN2), Formulation containing 3% Cocoamidopropyl Betain plus 3% Hydrophilyzed Cupuassu Butter (FN3) , Formulation containing 3% Cupuassu Betain plus 3% Hydrophilyzed Cupuassu Butter (FN4) and Formulation containing 3% Cupuassu Butter (FN6). Control is Bleached Tress only. Virgin hair is untreated. Box-plots were obtained from 40 hair fiber measurements from each hair sample.

Effects on Hair Gloss: No significant difference was observed in gloss measurements for any of the hair samples tested.

Discussion

Studies on the interaction of oils with human hair are rarely found in literature, although the use of these products in hair care products is very common. On the other hand, studies on the interaction of cationic compounds with hair fiber are easier to be found [7 - 10].

In this study, we observed that Cupuassu products, mainly Cupuassu Butter, have a positive effect on reducing moisture loss in hair, as well as on its mechanical properties. The same properties, especially hydro-retention, are also affected by a Placebo Formulation. These results are expected, since the Placebo Formulation contains a cationic compound (Cetrimonium Chloride), which is substantive to hair and adsorbs on hair surface following a charge-driven mechanism [4]. Ruetsch and Kamath [7] have demonstrated that penetration of such cationic compounds into hair fibers does occur. The authors have compared the ability of the cationic compounds Cetrimonium Bromide (CTAB) and Polyquaternium-10 (PQ-10) to penetrate into hair fiber and correlated the penetration of CTAB to its low molecular weight. PQ-10 is restricted to deposition on the hair surface.

Rele et al. [6] have recently compared the ability of different oils to penetrate into hair fibers, showing that their affinity to hair fiber depends on various factors, such as oil polarity, chain saturation and molecular weight. These authors have also shown that the penetrability of oils diminishes the thickness of the oil film on the hair surface, which is a critical factor to improve reduction of hair moisture loss. Since we observed changes in the mechanical properties of hair treated with Cupuassu and Shea Butters, we can assume that these butters penetrated the hair cortex. An improvement of around 30% in hair breaking tensile strength was observed for hair treated with a leave-on conditioner containing 1% of Cupuassu Butter, but such improvement was not observed for hair treated with a leave-on conditioner containing 1% of Shea Butter. On the other hand, a similar reduction of moisture loss provided by the leave-on containing 1% of Shea Butter was achieved with a leave-on containing 3% of Cupuassu Butter. The leave-on containing 1% of Cupuassu Butter presented moisture loss results similar to that obtained with the Placebo Formulation. Based on these results, we can suppose that: a) The film formed on the hair surface by the deposition of the different leave-on is not at all the same; b) The reduced improvement in mechanical properties provided by 1% Shea Butter, compared to 1% Cupuassu Butter, indicates it has lower penetration into hair fiber, and consequently, better film deposition. This better film deposition leads to an improvement in hair hydro-retention which proves that similar hydro-retention results would be achieved only with formulations containing higher concentrations of Cupuassu Butter.

Conclusion

Cupuassu products, mainly Cupuassu Butter, incorporated into cosmetics products, show a good performance on hair properties. We observed improvement in hair breaking tensile strength and hydro-retention. The improvement of hair properties provided by Cupuassu Butter is related to its good deposition on hair surface and capacity to penetrate the hair cortex.

Note

This topic was presented at the 24th International Federation of Societies of Cosmetic Chemists (IFSCC) Congress in Osaka, Japan, October 2006.

References

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3. Medeiros M. L., Ayrosa A. M. I. B., Pitombo R. N. M., Lannes S. C. S., Sorption Isotherms of Cocoa and Cupuassu Products, J. Food Eng., 73: 402-406, 2006.
4. Robbins C. R., Chemical and Physical Behavior of Human Hair, Springer-Verlag, New York, 4th ed., 2002.
5. Draelos Z. D., The biology of hair care, Dermatol. Clinics, 18: 651-658, 2000.
6. Keis K., Persaud D., Kamath Y. K. and Rele A. S., Investigation of Penetration Abilities of various Oils into Human Hair Fibers, J. Cosmet. Sci., 56: 283-295, 2005.
7. Ruetsch S. B. and Kamath Y. K., Penetration of Cationic Conditioning Compounds into Hair Fibers, J. Cosmet. Sci., 56: 323-330, 2005.
8. Holt L. A., Cationic-anionic surfactant interactions on wool: implications for the conditioning of human hair, J. Soc. Cosmet. Chem., 42: 351-359, 1991.
9. Reich C. and Robbins C. R., Interactions of cationic and anionic surfactants on hair surfaces: Light-scattering and radiotracer studies, J. Soc. Cosmet. Chem., 44: 263-278, 1993.
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Author

Ana Carolina Santos Nogueira



Ana Carolina Nogueira, Chemical Engineer, MSc, currently concluding a PhD focused in human hair research, joined Cognis in March 2005. She is responsible for HBO Technology in South America and her main activities are the development and evaluation of body and hair care products.

Cognis Brasil Ltda., Rodovia Presidente Dutra, Km 161, Jacareí, São Paulo, Brazil, 12335-010
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e-mail: ana.nogueira@cognis.com