THE ROLE OF PLANT OILS AS REFATTENING
COMPONENTS IN TWO-PHASE BATH LIQUIDS
Anna Małysa*, Emilia Klimaszewska, Małgorzata Zięba,
Olga Jagiello, Marlena Gruszczyńska, Maja Gajowiak
Kazimierz Pulaski University of Technology and Humanities in Radom
Department of Physical and Inorganic Chemistry, Chair of Chemistry
Faculty of Materials Science and Design
* Corresponding author: Chrobrego Str. 27, 26-600 Radom, [email protected]
Abstract: This article discusses the use of plant oils as re-fattening ingredients
in two-phase bath liquids. Based upon the analyses available literature, the formulas
of modern cleaning preparations in the two-phase form were developed. An important
was the selection of the type and concentration of oils: grape seed and sunflower oils
and surfactants. The subject of discussion was the effect of the examined ingredients
on the functional properties of original preparations, i.e. viscosity, foam-forming
ability, emulsification and separation time start. The point of reference
in the evaluation was a high-quality commercial product. The adipose (upper) phase
is characterized by significantly higher viscosity than the aqueous phase (lower)
in the produced bath liquids. The entire preparation shows higher viscosity
than the aqueous phase but lower than the adipose phase. The viscosity
of the preparations is affected by the concentration of plant oil, whereas its type causes
significant changes in viscosity. The highest foam ability was observed
in the preparation containing grape seed oil in the formula at the concentration of 2%.
In contrast, the lowest foam-forming abilities were found in the preparation
with sunflower seed oil in 6% concentration. All the preparations are characterized
by low emulsify ability of greasy impurities, which is a good symptom, because owing
to that they do not lead to skin dehydration, simultaneously retaining the washing
ability. It was found that the obtained original preparations show functional properties
comparable to their market counterparts.
Keywords: two-phase bath liquids, plant oils, re-fattening components
125
1. INTRODUCTION
A significant part of the cosmetics market are hygiene products,
in particular cleaning preparations. These are found in various forms, however,
bath liquids enjoy the highest popularity among customers. The saturation
of the market with a large number of products leads to the situation
where the selection of goods increasingly depends on marketing issues.
For consumers not only the effectiveness of the product is important, but also
a modern and attractive appearance that encourages them to buy. On the other
hand, from the manufacturer's perspective, the important factors are
undoubtedly: manufacturing technology and the use of innovative and safe
products. A perfect example of a modern form of cosmetic product are multiphase products. The largest group of preparations in such a form are bath
liquids, however, the multi-phase form is adopted by make-up removing,
hair-care products and bath oils [Wasilewski and Nachyla 2006, Sułek
and Małysa 2008, Malinowska 2010, Sułek and Małysa 2013].
This paper focuses on two-phase bath liquids with skin nourishing
properties. Two-phase bath liquids are water aqueous solutions of various
surfactant compositions (anionic, amphoteric, non-ionic, at times cationic)
and series of nourishing additions, such as: moisturizing, oiling substances,
herbal extracts, vitamins, essential oils, etc. [Williams and Schmitt 1992].
The two-phase form is attractive for the introduction of ingredients soluble
both in the aqueous and the adipose phases. The most commonly used
moisturizing ingredients are mineral oils. In view of the fact that in the recent
years more and more attention is paid to green living and natural environment
protection, a formula for a preparation containing natural vegetable oils
was developed in this paper. The replacement of synthetic raw materials
with natural ones increases the biodegradability and at the same time affects
the economy of manufacturing by reducing disposal costs. Another advantage
126
of two-phase liquids is the possibility to introduce substantially higher
concentrations of fatty raw materials, i.e. oils, vitamins, herbal macerates,
which is not possible in traditional bathing liquids [Mitsui 1998, Kuo-Yann
1997, Butler 2000, Chakrabarty 2003, Hiwatan et al. 2004]. Increasing
the content of lipophilic ingredients in their case might have a negative impact
on the stability of the product, cleaning or foam-forming properties.
The use both water-soluble and fatty substances in the two-phase bathing
liquids is beneficial because apart from the washing function, the product also
shows nourishing effect, mostly regenerating and moisturizing for the skin.
Traditional bath liquids may excessively dehydrate the skin, stripping it of the
natural lipid barrier, due to high content of surfactants. In two-phase liquids
the effect is minimized through the addition relatively high concentrations
of vegetable oils, which moisturize the skin already in the bath [Malinka 1999,
Sulek, Zieba, and Mazurek 2011, Hiwatan et al. 2004, Wennirger
and McEwen 1997, Zoller 2009, Porter 1994, Luders 2001].
In the production of multi-phase preparations, in addition to marketing
purposes, of crucial significance are without doubt the functional properties
that is foamability, cleaning and nourishing properties. Likewise, the important
features of each cosmetic product are consistency, ease of application
and the speed at which the preparation separates over time. This article presents
the physicochemical and functional studies of the developed two-phase bathing
liquid formulas containing sunflower seed and grapeseed oils as nourishing
ingredients [Friedman and Wolf 1996, Flick 1999, Showell 2006].
2. MATERIALS AND METHODS
The frame formulation was based on the analysis of the market
and the available literature data. This recipe was modified by changing
the sunflower seed and grape seed oils concentration. The raw materials used
127
in the formula are: INCI: Sodium Laureth Sulfate used as the main surfactant.
Also non-ionic surfactant was introduced in the formulation: lauryl alcohol
oxyethylated with 3 moles of ethylene oxide (INCI; Laureth-3), amphoteric
surfactant (INCI: Cocamidopropyl Betaine). The oily ingredients contained
in the formula are: INCI: Caprylic/Capric Trigliceryde, grapeseed oil
(INCI:Vitis Vinifera (Grape) Seed Oil) and sunflower seed oil (INCI:
Helianthus Annuus (Sunflower) Seed Oil). The formulas were modified
regarding the content of vegetable oil in the preparation. Five samples were
made for each of oil, at the concentrations of 2%, 4%, 6%, 8% and 10%,
marked with consecutive Roman numerals I-V. The formula for each sample
is presented in table 1.
The preparations were made through the dissolution of each ingredient
by intensive stirring in distilled water. Subsequently, the preparation was left
until the phases separated. The point of reference in the evaluation
of the functional properties of the obtained preparations was a high-quality
commercial product.
In order to determine foam ability, the procedure specified
in the PN-74/C-04801 standard was used. The volume of foam created
after 10 seconds by a 4% solution of the preparation was considered
the foam-forming ability. The foam ability was determined according
to the equation:
X=
where:
p ×5
×h
4
X- foam-forming ability [cm3];
5- internal diameter of the measuring cylinder [cm3];
h – recorded height of foam column [cm2].
128
The foam stability index (FSI) was calculated from the formula:
!" =
where:
#
# 100%$[%]
!"
V2 - foam volume after 10 minutes from creation [cm3]
V1 - foam volume after 1 from creation [cm3]
The result of the determination was an average from independent
measurements (h).
The dynamic viscosity was measured using Brookfield HA DV III Ultra.
The measurement was made at the rotational speed of 10 rpm. The final result
is an arithmetic mean from three measurements performed for each sample.
The emulsify ability was evaluated in accordance with the PN-C-77003
standard. The method consists in observing color changes in rapeseed
oil colored with Sudan red by a water solution of the tested preparation.
The results of fat emulsify ability tests for the obtained bathing liquids
are presented in a point-based scale 1-6, the higher the score, the better fat
emulsify ability shown by the given preparation.
The mean separation start time was determined by visually evaluating
the
samples
after
stirring
and
establishing
the
time
necessary
for the appearance of a visible, clear lower phase. The final result was
an average from three independent measurement series [Sułek and Małysa
2008, 2013, Wasilewski and Nachyla 2006].
129
Table 1. Formulas for produced preparations with various plant oils content
[wt. % ]
NAME
(INCI)
Grapeseed oil
Sunflower seed oil
I
II
III
IV
Aqua
up to
100
up to
100
up to
100
up to
100
Sodium Laureth
Sulfate
20.0
20.0
20.0
Caprylic/Capric
Trigliceride
13.0
11.0
Vitis Vinifera
(Grape) Seed
Oil
2.0
Helianthus
Annuus
(Sunflower)
Seed Oil
II
III
IV
V
up to up to
100
100
up to
100
up to
100
up to
100
up to
100
20.0
20.0
20.0
20.0
20.0
20.0
20.0
9.0
7.0
5.0
13.0
11.0
9.0
7.0
5.0
4.0
6.0
8.0
10
-
-
-
-
-
-
-
-
-
-
2.0
4.0
6.0
8.0
10
Laureth-3
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
Tetrasodium
EDTA
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
Cocamidopropyl
Betaine
0.4
0.4
0.4
0.4
0.4
0.4
0.4
0.4
0.4
0.4
Preservative
0.4
0.4
0.4
0.4
0.4
0.4
0.4
0.4
0.4
0.4
Parfum
q.s.
q.s.
q.s.
q.s.
q.s.
q.s.
q.s.
q.s.
q.s.
q.s.
Colour
q.s.
q.s.
q.s.
q.s.
q.s.
q.s.
q.s.
q.s.
q.s.
q.s.
Source: Authors’ own work
130
V
I
3. RESULTS AND DISCUSSION
3.1. Market research of two phase bath liquids
In order to analyze the two-phase bathing liquid market, information
concerning 80 products of 50 manufacturers was collected. The following were
taken into consideration: ingredients, intended use, capacity and price (PLN
per 100 ml). The analysis was performed in January 2015 at hypermarkets
and beauty shops in the city of Radom and through online sales outlets.
The analysis of the results of the conducted market study indicates
that the offer of two-phase bath liquids is very diverse. There is a wide range
of the prices from PLN 10-160 per 1000 ml of the liquid. Most frequent
on the market are bath liquids priced PLN 40-43 per 1000 ml, which account
for 30% of the tested preparations. They are available for sale in various
bottles, always made of plastics, so that their two-phase form, which attracts
customer attention, can be visible. The capacity packaging of the two-phase
liquid are the range of 200-1000 ml. The largest group are products available
in containers of 200-250 ml, which account for 54% of the tested preparations.
The least frequent are, in contrast, products of the highest capacity of 1000 ml,
only one manufacturer offers such a product.
The analyses of the composition of two-phase bath liquids were made
according to the INCI ingredient listings placed on packaging. It was observed
that the most frequently used ingredients in the liquids of this type are:
INCI: Paraffinum Liquidum, PEG-Hydrogenated Castor Oil, Cocamidopropyl
Betaine, present in 90% of the analyzed preparations. Plant extracts are present
in 70% of the tested products. Natural oils are present in merely 30%
of the preparations, whereas in 85% of the two-phase bath liquids available
on the market the adipose phase is mineral oil (Paraffinum Liquidum).
Due to the market niche among bath products containing natural plant oils, an
131
attempt was made at developing formulas for preparations containing grape
seed and sunflower seed oils.
3.2. The influence of plant oils on the functional properties of two-phase
bath liquids
Foam-forming abilities assessment
The foam ability of bathing preparations is the main criterion for their
quality assessment. The abundance and stability of foam significantly affects
the aesthetic qualities of a bath. In order to determine foam ability,
the procedure specified in the PN-74/C-04801 standard was used. Test results
Foam volume [cm3]
are provided in Fig. 1 and Fig. 2.
grapeseed oil
240
200
160
120
80
40
0
2
4
sunflower seed oil
6
8
Concentration [%wt.]
10
Trade
Product
Figure 1. Dependence of volume created foam of two-phase bath liquids
on the grapeseed oil and sunflower seed oil concentration. Source: Authors’ own work
Based on the obtained results it was found that the addition of sunflower
seed oil within the concentration of 2% to 10 % has the effect of reducing
the volume of foam created by solutions of the tested two-phase bath liquids
from 200 cm3 to 160 cm3. In the case of grape seed oil one may assume
that its increasing concentration in the product has practically no effect
132
on its foam-forming properties, which remained on the average level of 220
cm3, analogously to the commercial product.
The courses of changes in foam volume based on plant oil concentration
correspond well with the determined foam stability index (FSI) presented
Foam stability index [%]
in Fig. 2.
grapeseed oil
120
100
80
60
40
20
0
2
4
sunflower seed oil
6
8
10
Concentration [%wt.]
Trade
Product
Figure 2. Dependence of foam stability index (FSI) of two-phase bath liquid on the
grape seed oil and sunflower seed oil concentration. Source: Authors’ own work
The original preparations containing grape seed oil formed heavier
and more stable foam. The one to obtain the highest foam stability index (96%)
was the cosmetic product containing 2% of the oil. For higher concentrations
the FSI remained at relatively high levels from 87% to 91%. The obtained
FSI values were comparable to the commercial product.
A lower FSI was achieved by liquids containing sunflower seed oil.
Foam stability deteriorated with increasing concentrations of the discussed
addition. For the oil concentrations of 2%- 6%, FSI was approximately 80%,
while for the addition of 8% and 10% of the oil, the FSI achieved the value
of 60% and 55%.
133
Viscosity
The viscosity of bath products is the basic value that characterizes
their physicochemical properties. Although such products are not required
to have high viscosity, in the case of two-phase bathing liquids it usually varies
for various phases, as well as for the entire preparation after mixing.
The viscosity of two-phase compositions may also affect their functional
properties. Too pronounced differences in viscosity of the two phases might
hinder even dosage of the preparation. The measurements of dynamic viscosity
were made for the individual phases and the preparations in their entirety
with a different composition of the adipose phase. Test results are provided
in Fig. 3 and Fig. 4.
Viscosity [mPa · s]
100
whole composition
emulsion phase
aqueous phase
80
60
40
20
0
2
4
6
8
10
Concentration of grapeseed oil [%wt.]
Trade
Product
Figure 3. Dependence of viscosity of: the whole compositions, emulsion phases
and aqueous phases on the grape seed oil concentration, measurement temperature
22° C. Source: Authors’ own work
The demonstrated results indicate that the gradation of viscosity changes
for each preparation is decreasing in the sequence: upper phase, preparation
after mixing, lower phase. The one to score the highest viscosity values
was the commercial product.
134
No significant impact of the discussed oils concentration on the changes
in viscosity of both the entire preparation and its individual phases
was observed. The changes were slight, within the range of experimental error.
Viscosity [mPa · s]
100
whole composition
emulsion phase
aqueous phase
80
60
40
20
0
2
4
6
8
10
Concentration of sunflower seed oil [%wt.]
Trade
product
Figure 4. Dependence of viscosity of: the whole compositions, emulsion phases
and aqueous phases on the sunflower seed oil concentration, measurement
temperature 22° C. Source: Authors’ own work
Fat emulsify ability
One of the essential functional properties of washing preparations
is the ability to emulsify fat. It is crucial that a bathing liquid remove impurities
and show moderate fat emulsification properties due to the possible
dehydration of the skin.
The results of the conducted tests indicate that the produced preparations,
as does the market product, show moderate fat emulsification properties,
which remain at the level of 2-3 points (Fig. 5). The obtained results clearly
illustrate that the produced preparations have mild emulsifying properties
and thus show delicate effect on the skin. They do not excessively remove
the lipid layer from the skin, at the same time retaining cleaning properties.
135
Fat emulsification [pkt]
grapeseed oil
6
5
4
3
2
1
0
2
4
sunflower seed oil
6
8
10
Concentration [%wt.]
Trade
Product
Figure 5. Fat emulsification of two-phase bath liquids containing grape seed
and sunflower seed oils. Source: Authors’ own work
Separation start time
The parameter of phase separation start time is crucial due
to the functional properties of two-phase bath liquids. A product with good
properties cannot separate too quickly since it will render correct application
Separation start time
[min.]
impossible and thus result in incomplete utilization of its functions.
grapeseed oil
30
25
20
15
10
5
0
2
4
sunflower seed oil
6
8
Concentration [%wt.]
10
Trade
Product
Figure 6. Separation start time of two-phase bath liquids containing grape seed
and sunflower seed oils. Source: Authors’ own work
136
The results of separation start time measurement indicate that bathing
liquids containing grapeseed oil start to separate quicker than the ones
with sunflower seed oil. The separation of market product phases occurred
after 15 minutes from stirring (Fig. 6). The closest phase separation start time
to the commercial product was shown by the preparation containing sunflower
seed oil at the concentrations of 8 and 10%.
4. CONCLUSIONS
The article presents the developed formulas for two-phase bath liquids
with emulsive upper phase and clear lower phase. The testing of physicochemical and functional properties included a commercial product
and preparations differing as to how much grape seed and sunflower seed oil
was added. The ingredients of the formulas were determined based
on the analysis of two-phase bath liquids available on the market and the frame
formula. The effect of concentration of the discussed additions on the selected
physicochemical and functional properties of the obtained preparations
was analyzed: foam ability, viscosity, fat emulsification and separation start
time of the preparation.
It was found that the produced preparations, in particular those
containing grape seed oil, are characterized by good foam-forming properties
in comparison to the market product. The created foam is thick, creamy
and stable over time.
The adipose (upper) phase is characterized by significantly higher
viscosity than the aqueous phase (lower) in the original two-phase bath liquids.
The entire preparation shows higher viscosity than the aqueous phase but lower
than the adipose phase. Increased concentration of the two oil additions did not
have a substantial impact on viscosity.
137
Taking into consideration the emulsifying properties, it is always clear
that both the produced preparations and the reference product have a moderate
fat emulsification capability. In the case of bath liquids it is beneficial, because
it attests their nourishing properties in relation to the skin.
Comparing the separation start time of two-phase bath liquids with plant
oils, one may ascertain that the separation of phases occurs quicker in the case
of sunflower seed oil. The ingredients of the preparations remain in uniform
composition, which ensures proper dosage of the liquid and the desirable
nourishing effect. It should be noted that the start time of separation
of the original preparations with the discussed addition at the concentrations
of 8% and 10% is identical to that of the commercial product.
The developed formulas for bath liquids may warrant further research
and modification of the formulas for two-phase bath cosmetic products.
The two-phase form is innovative and offers numerous possibilities
both to obtain many interesting visual compositions and to introduce higher
concentrations of innovative, hydrophobic cosmetic ingredients.
5. ACKNOWLEDGMENTS
This study was supported by the project of Kazimierz Pulaski University
of Technology and Humanities in Radom, No POKL.04.01.02-00-192/12.
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STRESZCZENIE
W
artykule
przedstawiono
możliwość
wykorzystania
olejów
roślinnych
jako składników renatłuszczających w dwufazowych płynach do kąpieli.
Na podstawie analizy dostępnej literatury opracowano receptury nowoczesnych
preparatów myjących w formie dwufazowej. Istotnym był dobór rodzaju i stężenia
olejów: z pestek winogron i słonecznikowego oraz związków powierzchniowo
czynnych. Dyskutowano wpływ omawianych komponentów na cechy użytkowe
oryginalnych preparatów tj. lepkość, pianotwórczość, emulgowanie i czas początku
rozwarstwiania. Punktem odniesienia w ocenie był wysokiej jakości produkt
handlowy. W wykonanych płynach do kąpieli znacznie większą lepkością
charakteryzuje się faza tłuszczowa (górna) preparatu niż faza wodna (dolna).
Całość preparatu wykazuje lepkość wyższą od fazy wodnej, ale niższą od fazy
tłuszczowej. Na lepkość preparatów wpływa stężenie oleju roślinnego, natomiast
jego rodzaj powoduje znaczących zmian lepkości. Największą zdolność do tworzenia
piany wykazywał preparat zawierający w swoim składzie olej z pestek winogron
w stężeniu 2%. Natomiast najmniejsze zdolności pianotwórcze wykazał preparat
z olejem słonecznikowym w stężeniu 6%. Wszystkie preparaty charakteryzują się
słabą zdolnością emulgowania zabrudzeń tłuszczowych, co jest dobrym objawem,
gdyż dzięki temu nie wysuszają skóry jednocześnie zachowując zdolności do jej
mycia. Wykazano, ze otrzymane oryginalne preparaty wykazują właściwości
użytkowe porównywalne z ich odpowiednikiem rynkowym.
Słowa kluczowe: dwufazowe płyny do kąpieli, oleje roślinne, składniki
renatłuszczające
140