80 FUNCTIONAL INGREDIENTS
bottom and middle notes. Traditionally fragrance fixatives have been
natural materials such as resins, musks and ambergris. The latter are animal-derived and rarely used anymore. Modern fixatives are synthetic musks (e.g. galaxolide), essential oils (e.g. patchouli and sandalwood), and synthetic polymers (e.g. cyclodextrins and silicones). Many more examples can be found in the patent literature.6, 7 The musks and essential oils are not
odourless and should be formulated as part of the fragrance. Cyclodextrins encapsulate the fragrance molecules to retard their evaporation, but they are very polar and not suitable for all ingredients. Silicones work well, but do not biodegrade and accumulate in the environment after use. Polycitronellol is a new fragrance additive that possesses fixative and odour masking properties. It is made from natural pine-derived terpenes by a manufacturing process based on the principles of green chemistry.8
This material
provides hydrolytic stability while being 100% biorenewable, bioderived, biodegradable and biocompatible.9 In this article, we will demonstrate the
performance of Polycitronellol as a fragrance enhancer. We will show that it outperforms competitive materials. Polycitronellol can be used as a fragrance ingredient, but it can also be added to finished product formulations to prolong the fragrance presence.
Experiments Test fragrance formulation The compositions of the test fragrance formulations are given in the text. All chemicals were obtained from Sigma-Aldrich, except Glucam P20 (PPG-20 Methyl Glucose Ether, Lubrizol) and Anthamber (Tetramethyl acetyloctahydronaphthalenes, VIGON). Polycitronellol was provided by P2 Science; it has a very light odour that only impacts the fragrance at high concentrations.
50 45 40 35 30 25 20 15 10 5 0
Polycitronellol Isobutyrate
Sucrose Acetate
Glucam P20 TEC (no fixative) Control Level of Polycitronellol in fragrance
Figure 1: Polycitronellol retains more Dihydromyrcenol and Carvone after 6 hours compared to all other fragrance enhancers tested (Dihydromyrcenol indicated by the dark bars, Carvone indicated by the light bars)
PERSONAL CARE September 2024
Figure 2: Dihydromyrcenol and Carvone levels in the model fragrance with different levels of Polycitronellol after four hours ageing
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Analytical evaporation test This test measured the effect of fragrance fixatives on the evaporation rate of fragrance molecules over time at a set temperature in a model fragrance formulation. A measured amount of formulation mixture was transferred to an aluminium container and placed on a hot plate at 32°C for evaporation. Mixtures were tested at pre-determined
time intervals (i.e. zero hours, 30 minutes, four hours, and six hours) and extracted. A gas chromatograph (GC) measured the amount of fragrance present in each sample quantitatively. An internal standard controlled for variation during the evaporation test. At each time point, the GC response (peak area) of fragrance material and internal standard were recorded. The ratio of fragrance and internal standard
was calculated and corrected by a calibration factor. The first time point at zero hours was set as non-evaporated fragrance material. The evaporation of fragrance molecules over time
60 50 40 30 20 10 0
0% 0.5% 1% 2% 5% 10%
compared to the initial amount was reported as a percentage. To compare the performance of fragrance
fixatives, we used a model fragrance consisting of equal amounts of a top note (Dihydromyrcenol), heart note (Carvone), and base note (Anthamber) with fixatives set at a 10% composition. The test formulation is shown in Table 1. In a second test, we compared different
levels of Polycitronellol between 0.5% and 10% in the fragrance (Table 2). In this testing, Anthamber was removed from the fragrance composition to ensure that fixation was provided primarily by Polycitronellol.
Sensory evaluation To test the performance of the selected fixative products, we conducted a sensory test that compared the effectiveness of three fixatives used at 2% in alcoholic solutions (Table 3). Blotters were dipped in the test samples, labeled with random numbers to avoid
Dihydromyrcenol ■ Carvone ■
TABLE 3: TEST EAU DE TOILETTE FORMULATIONS IN COMPARATIVE EVALUATION OF FRAGRANCE FIXATIVES
Ethanol (192 proof) DI Water
Fragrance (Mandarin Berry Fragrance from Making Cosmetics)
Sucrose Acetate Isobutyrate (SAIB)
Triethyl Citrate (TEC) Polycitronellol
Control (no fixative) 80% 10%
10%
- -
-
SAIB sample 80% 8%
10%
2% -
-
Ethanol (192 proof) DI Water
10% Polycitronellol q.s. 5%
4.7% 10%
TEC sample 80% 8%
10% -
2% -
5% Polycitronellol q.s. 5%
4.7% 5%
Polycitronellol sample 80% 8%
10%
- -
2%
TABLE 4: MODEL EAU DE TOILETTE COMPOSITIONS USED IN DIRECTIONAL DIFFERENCE SENSORY TEST Control q.s. 5%
2% Polycitronellol q.s. 5%
Fragrance (In-house blend) Polycitronellol
4.7% -
4.7% 2%
% Dihydromyrcenol or Carvone remaining after 6 hours
% of fragrance ingredient remaining after 4 hours
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