The non-linear optical responses of cherry seed oil, avocado seed oil, and sesame oil were studied by observing spatial self-phase modulation (SSPM) in oil samples using a \(405\,nm\) continuous wave laser beam. The non-linear refraction coefficients and third-order non-linear susceptibility\({\chi ^{\left( 3 \right)}}\)of edible oils were estimated to be \({10^{ - 6}}\,c{m^2}/W\)and\({10^{ - 5}}\,esu\), respectively, based on the intensity-dependent number of observed symmetric diffraction rings. Also, we examined the spatial self-phase modulation technique to investigate the authenticity of three adulterated oils based on their non-linear optical properties. For this purpose, five different adulterated samples were prepared by diluting samples with sunflower oil (cheaper commercial oil) in various dilution ratios. The measured non-linear optical parameters of adulterated samples revealed that the non-linear optical parameters of diluted oils correlate strongly with the samples' levels of adulteration. The results suggest that the SSPM technique might be considered for estimating the degree of adulteration of samples based on their non-linear optical responses.
Research Article
Non-linear optical response as a food authentication: Investigation of non- linear optical properties of edible oils by Spatial Self-Phase Modulation (SSPM) method
https://doi.org/10.21203/rs.3.rs-2121251/v1
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Non-linear optical response
Spatial self-phase modulation (SSPM)
Cherry seed oil
Avocado seed oil
Sesame oil
Food authentication
The invention of the laser by Theodore H. Maiman in 1960 (Maiman 1960) enabled scientists to observe various previously unknown phenomena due to the lack of high-density electromagnetic energy sources. Franken and his colleagues (Franken et al. 1961) were the first to notice the Second Harmonic Generation (SHG) in 1961, providing a foundation for non-linear optics, which studies the optical properties of materials when exposed to a high-energy electromagnetic field. When a sample with non-linear optical characteristics is excited with a higher power density, it may exhibit changes in its optical properties such as refractive index, polarization, and absorption coefficient variations. Non-linear optics describe and study all these phenomena (Boyd 2020).
The development of science and technology in recent decades has led to the implementation of new electronic and optoelectronic devices. Due to their wide range of applications in optical and photonic devices, such as optical limiting (Marbello O et al. 2020), optical switching (Henari and Cassidy 2012), and optical communication (Wong et al. 1991), most researchers are currently concentrating on exploring materials with high non-linear optical responses. On the other hand, studying non-linear optical properties ensures sample authenticity and purity (Ribeiro et al. 2019) and sample differentiation (de Souza et al. 2020). Several methods are currently available to determine the non-linear characteristics of materials, including elliptical rotation, the measurement of beam distortion, interference of two or four waves, Z-Scan, and Spatial Self Phase Modulation (SSPM) (Li 2017). Using the mentioned above techniques makes it possible to evaluate the non-linear behavior of many materials, some of which are experimentally more complex than others. When an intense beam of light passes through a non-linear medium, the optical Kerr effect causes the medium's refractive index to change (Boyd 2020). The intensity-dependent refractive index causes the refractive index to vary, resulting in a phase shift in the light caused by the spatial self-phase modulation event. The appearance of ring-shaped diffraction patterns characterizes this optical phenomenon. The origin of these rings is the additional phase shift of the light beam with a Gaussian profile that occurs when the medium is heated (Yang et al. 2005). Diffraction patterns are noticeable when the absorption coefficient of the medium is high enough; however, when the absorption coefficient of the medium for a given light source is low, only a small amount of power is absorbed by the medium; in this case, less heat is generated, and only a minor phase shift occurs, so the rings are not observable.
In recent years, scientists have demonstrated that vegetable oils such as olive oil (Marbello O et al. 2020; Mousavi et al. 2019), palm oil (Zamiri et al. 2012), castor oil (Souza et al. 2006), and a few other edible oils (Marbello et al. 2019) exhibit highly non-linear responses. Most vegetable oils are edible, particularly those derived from fruit seeds and other parts (Gunstone 2011). Organic oils and fats exist as combinations of glycerides in liquid or solid phases depending on temperature, as well as minor molecules such as free fatty acids, hydrocarbons, vitamins, phospholipids, waxes, pigments, and sterols (Alfred et al. 2002). Edible vegetable oils are now vitally important since they play an essential role in the daily diet and are extensively used in domestic and commercial cooking (Gouilleux et al. 2018). Because of this, much fraud is associated with producing vegetable oils; one of the ways of adulterating oils is to replace original oils with cheaper ones (Moore et al. 2012). In order to authentication of the various vegetable oils, a variety of methods such as: Gas chromatography-mass spectrometry (Mota et al. 2021), Fourier transform infrared (FTIR) spectroscopy (Sota-Uba et al. 2021), and UV-Visible spectroscopy (Ok 2017), have been suggested. Consequently, investigation and verification of the authenticity of edible vegetable oils are essential.
This work reports, the non-linear optical response of avocado seed oil, cherry seed oil, and sesame oil by measuring two optical characteristics, including the non-linear refractive index \({n_2}\) and the third-order non-linear electric susceptibility \({\chi ^{\left( 3 \right)}}\) of these vegetable oils at the wavelength of \(405\,nm\). The analysis was performed using the well-known SSPM technique, a straightforward and accurate method for investigating the non-linear responses of the samples (Jia et al. 2019; Shan et al. 2019). Also, in order to authenticate the various vegetable oils, the authenticity of three types of vegetable oils was investigated based on their non-linear optical properties by using the SSPM technique. Furthermore, we performed sample authentication using the non-linear response of vegetable oils. This technique introduces a cheap, rapid, and simple method for detecting food adulteration so that the obtained results can be used to determine the authenticity of vegetable oils.
1.1 Sample preparation
Edible oils are extracted from various plant and animal sources, which have various metabolic, physical, and chemical properties. Different oil extraction processes are available depending on the source of the oil. In extracting vegetable oil, triglycerides must be separated from oil-containing kernels, seeds, or pulps. Vegetable oil can be produced using various mechanical, chemical, and biological techniques (Nde and Foncha 2020; Qin and Zhong 2016; Hasenhuettl 2000). Mechanical oil extraction extracts vegetable oil from oil seeds using a screw or press (Cakaloglu et al. 2018; Kazempour-Samak et al. 2021). Three types of vegetable oils (Sesame oil, Avocado seed oil, and Cherry seed oil) used in this work were obtained mechanically using the mechanical cold-pressing technique. Oil extraction is performed only under pressure in this technique, and unlike all existing methods, no heat or solvent is employed. All samples are prepared by separating the seeds from external materials; a suitable pressing machine extracts the oils after the seeds have been cold-pressed. The extracted oils were centrifuged and filtered to remove unwanted contaminants. In addition, to evaluate the samples' authenticity and adulteration based on their non-linear response, each oil sample is diluted with sunflower oil at five different concentration ratios: 1:0, 2:1, 1:1, 1:2, and 0:1. The ratio 1:0 indicates that the oil is undiluted. Furthermore, the ratios 2:1, 1:1, and 1:2 imply the addition of 33.33%, 50%, and 66.66% of sunflower oil, respectively. The 0:1 ratio refers to the experimental sample containing 100% sunflower oil.
1.2 SSPM Method
In the optical system, the non-linearity of the medium can be observed when the intense laser beam is transmitted through the non-linear medium, and the non-linearity is demonstrated in the polarization of the material, which the polarization intensity \(P(t)\) can express by (Li 2017; Liao et al. 2020):
$$P(t)={\varepsilon _0}\left\{ {{\chi ^{(1)}}E(t)+{\chi ^{(2)}}E{{(t)}^2}+{\chi ^{(3)}}E{{(t)}^3}+...} \right\}$$
1
Where\({\varepsilon _0}\)is the vacuum electric permittivity,\(E(t)\),\({\chi ^{(1)}}\),\({\chi ^{(2)}}\), and \({\chi ^{(3)}}\)are the optical field intensity, linear susceptibility, second-order and third-order susceptibilities, respectively. In the Eq. (1), the first term represents the linear optical effect, the second term refers to the second-order non-linear optical effect, and the third term describes the third-order non-linear optical effect. According to the optical Kerr effect (Sheik-Bahae and Hasselbeck 2000), when the light beam with a gaussian intensity profile and fundamental mode (TEM00) is transmitted through the non-linear medium length along the z-axis, the refractive index will be changed, and this change with the square of the applied light intensity is proportional. With the isotropic medium, the total refractive index can be expressed as follows:
$$n={n_0}+\Delta n$$
2
Where \({n_0}\) is the linear refractive index, and \(\Delta n={n_2}I\) is the change of the refractive index, \({n_2}\) is the non-linear refractive index, and \(I={{2P} \mathord{\left/ {\vphantom {{2P} {\pi \omega {{(z)}^2}}}} \right. \kern-0pt} {\pi \omega {{(z)}^2}}}\) is the intensity of the laser beam, is the power of the laser, and \(\omega (z)={\omega _0}\sqrt {1+{{\left( {{z \mathord{\left/ {\vphantom {z {{z_0}}}} \right. \kern-0pt} {{z_0}}}} \right)}^2}}\) is the beam radius at the propagation length, \({\omega _0}\) is beam waist radius, and \({z_0}={{\pi \omega _{0}^{2}} \mathord{\left/ {\vphantom {{\pi \omega _{0}^{2}} \lambda }} \right. \kern-0pt} \lambda }\) is the Rayleigh length, where \(\lambda\) is the wavelength of the laser beam. The light electric field distribution at the incident plane of the medium \(\left( {r,z} \right)\) can be written as (Deng et al. 2005):
$$E(r,z)=E(0,z)\exp \left( { - \frac{{{r^2}}}{{\omega {{(z)}^2}}}} \right)\exp \left( { - i\frac{{k{n_0}{r^2}}}{{2R(z)}}} \right)$$
3
Moreover, the electric field distribution on the exit plane \(\left( {r,z+L} \right)\) can be written as:
$$E(r,z+L)=E(0,z)\exp \left( { - \frac{{\alpha L}}{2}} \right)\exp \left( { - \frac{{{r^2}}}{{\omega {{(z)}^2}}}} \right)\exp \left( { - i\phi \left( r \right)} \right)$$
4
where \(E\left( {0,z} \right)\) is the electric field of the incident plane center of the medium, is the radial coordinate, \(\omega (z)\)is the beam radius at the medium incident plane, \(k={{2\pi } \mathord{\left/ {\vphantom {{2\pi } \lambda }} \right. \kern-0pt} \lambda }\) is the wave vector, \(R(z)=z\left( {\,1+{{\left( {{{{z_0}} \mathord{\left/ {\vphantom {{{z_0}} z}} \right. \kern-0pt} z}} \right)}^2}} \right)\) is the radius of curvature of the wave front in the corresponding position, \(\alpha\) is the linear absorption coefficient, and \(\phi \left( r \right)\) is the total phase shift which involves of the additional transient phase shift produced by the transition of the beam through the medium (non-linear phase shift\(\Delta {\phi _{NL}}\left( r \right)\)) and the Gaussian phase shift determined by the radius of curvature (change in linear phase\(\Delta {\phi _L}\left( r \right)\)), which expressed as follows (Li et al. 2020):
$$\phi \left( r \right)=\Delta {\phi _L}\left( r \right)+\Delta {\phi _{NL}}\left( r \right)$$
5
where
$$\Delta {\phi _L}\left( r \right)=\frac{{k{n_0}{r^2}}}{{2R\left( z \right)}}$$
6
$$\Delta {\phi _{NL}}\left( r \right)=\left( {\frac{{2\pi {n_0}}}{\lambda }} \right)\int\limits_{0}^{{{L_{eff}}}} {{n_2}I\left( {r,z} \right)} dz$$
7
Where \({L_{eff}}={z_0}\arctan \left. {\left( {{z \mathord{\left/ {\vphantom {z {{z_0}}}} \right. \kern-0pt} {{z_0}}}} \right)} \right|_{{{L_1}}}^{{{L_2}}}\) is the effective length of the optical propagation, \({L_1}\) and \({L_2}\) are the distance between the front and back surfaces of the cuvette and the light focus position, respectively, as shown in Fig. 1. Also \(I\left( {r,z} \right)={I_0}{\left( {1+\left( {{{{z^2}} \mathord{\left/ {\vphantom {{{z^2}} {z_{0}^{2}}}} \right. \kern-0pt} {z_{0}^{2}}}} \right)} \right)^{ - 1}}\exp \left( {{{ - 2{r^2}} \mathord{\left/ {\vphantom {{ - 2{r^2}} {\omega _{0}^{2}}}} \right. \kern-0pt} {\omega _{0}^{2}}}} \right)\) is the intensity distribution of the laser beam and \({I_0}\)is the intensity of the laser beam at the center of the Gaussian profile. Now, by using \(I\left( {r,z} \right)\) in Eq. (7), we obtain:
$$\Delta {\phi _{NL}}\left( r \right)=\frac{{2\pi {n_0}{n_2}{I_0}{L_{eff}}}}{\lambda }\exp \left( { - \frac{{2{r^2}}}{{\omega _{0}^{2}}}} \right)$$
8
SSPM diffraction patterns are observed when the phase difference between any two points \({r_1}\) and \({r_2}\) in the radial direction of the Gaussian beam establishes the relation \(\Delta \phi \left( {{r_1}} \right) - \Delta \phi \left( {{r_2}} \right)=m\pi\) ( is an integer number). The bright and dark rings occur when is even and odd, respectively. The phase difference between the center of the Gaussian beam intensity (\({r_1}=0\)) and the infinity (\({r_2}=\infty\)) with the rings, satisfied (Durbin et al. 1981):
$$\Delta \phi \left( 0 \right) - \Delta \phi \left( \infty \right)=2N\pi$$
9
From Eq. (8), \(\Delta \phi \left( \infty \right)=0\) and \(\Delta \phi \left( 0 \right)={{2\pi {n_0}{n_2}{I_0}{L_{eff}}} \mathord{\left/ {\vphantom {{2\pi {n_0}{n_2}{I_0}{L_{eff}}} \lambda }} \right. \kern-0pt} \lambda }\), Then
$${n_2}=\frac{\lambda }{{2{n_0}{L_{eff}}}}\frac{N}{I}$$
10
It is easy to determine the non-linear refractive index \({n_2}\) of materials using Eq. (10). The third-order non-linear susceptibility\({\chi ^{\left( 3 \right)}}\)(in the Gaussian unit) is defined by (Wu et al. 2016):
$${\chi ^{\left( 3 \right)}}=\frac{{c\lambda {n_0}}}{{2.4 \times {{10}^4}{\pi ^2}{L_{eff}}}}\frac{{dN}}{{dI}}=\frac{{n_{0}^{2}c}}{{12{\pi ^2}}}{10^{ - 7}}{n_2}$$
11
Figure 1 is a schematic diagram of the SSPM experimental setup. The blue continuous-wave (CW) laser with a wavelength of \(405\,nm\) was utilized as incident light to study the SSPM effect in oil samples. The laser beam passed through the spatial filter, the lens (\(f=100\,mm\)), and then the sample, which was filled in a \(10\,mm\)thick quartz cuvette. The distance between the focal point of the lens and the sample\({L_1}\) was adjusted to \(5\,mm\) in our experiments. \({L_2}\)value was the quartz sample cell thickness plus\({L_1}\)(i.e.,\({L_2}=15\,mm\)). The\({1 \mathord{\left/ {\vphantom {1 {{e^2}}}} \right. \kern-0pt} {{e^2}}}\)intensity radius at the center of the cuvette is measured to be \({\omega _0}=50\,\mu m\), yielding to \({z_0}=19.4\,mm\)and\({L_{eff}}=7.87\,mm\). The irradiation-induced phase-shift in oil samples, generated the SSPM phenomenon, and resulted to observe diffraction ring as it passed through the samples. The diffraction ring patterns were captured by a CCD camera (Camera EOS Kiss X50) on a black screen\(260\,cm\)behind the sample quartz cuvette.
2.1 UV-Visible absorption spectroscopy results
Figure 2(a) shows the UV-Vis spectra (PHYSTEC-UVS-2500) of cherry seed oil, avocado seed oil, and sesame oil. These spectra were used to investigate samples’ absorption at a given laser wavelength. It is found that all selected samples exhibit absorption at a wavelength of \(405\,nm\). It is clear that the cherry seed oil sample, has the highest absorption at \(405\,nm\) with the absorption coefficient \(\alpha =1.26\,c{m^{ - 1}}\). Meanwhile, avocado seed oil and sesame oil exhibit a lower absorption coefficient value, with \(\alpha =0.62\,c{m^{ - 1}}\) and \(0.33\,c{m^{ - 1}}\), respectively. In order to authenticate the various vegetable oils based on their non-linear optical properties, diluted oil samples with cheaper oil (sunflower oil) in five dilution rates of 1:0, 2:1, 1:1, 1;2, and 0.1 were prepared. Figure 2(b) shows UV-Vis spectrum of sunflower oil. Figure 3(a, b, and c) show UV-Vis spectra of diluted Avocado seed oil, Cherry seed oil, and Sesame oil at different dilution grades, respectively.
3. 2 Sspm Results
When the Gaussian laser beam passes through the oil, the temperature of the sample rises due to the medium's light absorption, particularly at the focal point of the laser light. Increasing the medium's temperature causes a change in the non-linear refractive index. A sample with a larger linear absorption coefficient for a particular wavelength absorbs more light at a specific wavelength, causing a greater thermal effect on the medium. As a result, the non-linear refractive index changes more significantly, indicating that the sample exhibits highly non-linear optical behavior. In our experiment, the first ring was formed when the power of the laser beam reached the threshold power \({P_{th}}\). It is found that the required threshold power (or certain power) for observing the first (or a certain number) ring(s) for each sample is distinct, implying that each sample exhibits specific non-linear behavior. Table 1 shows the required \({P_{th}}\) for each vegetable oils. The results indicate that the required threshold power \({P_{th}}\) for cherry seed oil to reveal the first diffraction ring is lower than that of the other two oil samples. This indicates that cheery seed oil has more non-linear optical properties than avocado seed oil, whereas avocado seed oil has more non-linear optical behavior properties than sesame oil. These results are compatible with the samples' ability to absorb light at a specific wavelength.
The SSPM induced diffraction ring pattern appears as the laser power gradually increases. Increasing the power causing new rings to emerge from the center of the diffraction pattern and increases the number and radius of the rings. Figure 4(a, b, and c) shows the CCD-captured diffraction ring patterns for cherry seed oil, avocado seed oil, and sesame oil with different incident beam powers at \(405\,nm\) wavelengths. The variations in the number of rings generated by changing the laser beam's incident intensity are shown in Fig. 5. Clearly, the relationship between the number of rings and the intensity is linear with a slope of \({{dN} \mathord{\left/ {\vphantom {{dN} {dI}}} \right. \kern-0pt} {dI}}\). The properties of non-linear optical properties of samples become more evident when the slope of the fitted line \({{dN} \mathord{\left/ {\vphantom {{dN} {dI}}} \right. \kern-0pt} {dI}}\) is increased. Using \({n_0}=1.47\)(Arya et al. 1969), and a slope of \({{dN} \mathord{\left/ {\vphantom {{dN} {dI={\text{0}}{\text{.096}}\,c{m^2}/W}}} \right. \kern-0pt} {dI={\text{0}}{\text{.096}}\,c{m^2}/W}}\), \({{dN} \mathord{\left/ {\vphantom {{dN} {dI={\text{0}}{\text{.175}}\,c{m^2}/W}}} \right. \kern-0pt} {dI={\text{0}}{\text{.175}}\,c{m^2}/W}}\), and \({{dN} \mathord{\left/ {\vphantom {{dN} {dI={\text{0}}{\text{.034}}\,c{m^2}/W}}} \right. \kern-0pt} {dI={\text{0}}{\text{.034}}\,c{m^2}/W}}\), respectively, we derived non-linear refractive indexes of \({n_2}=1.68 \times {10^{ - 6}}\,c{m^2}/W\) for avocado seed oil, \({n_2}=3.06 \times {10^{ - 6}}\,c{m^2}/W\)for cherry seed oil, and \({n_2}=6 \times {10^{ - 7}}\,c{m^2}/W\)for sesame oil. According to Eq. (11), the relation between \({\chi ^{\left( 3 \right)}}\)and \({n_2}\) is proportional. Then, we estimated that for cherry seed oil, avocado seed oil, and sesame oil the value of non-linear susceptibility\({\chi ^{\left( 3 \right)}}\)are equal to \(16.8 \times {10^{ - 5}}esu\), \(9.18 \times {10^{ - 5}}esu\), and \(3.28 \times {10^{ - 5}}esu\), respectively. Table 1 lists all the parameters that were measured in this study. The results reveal that the three vegetable oils: cherry seed oil, avocado seed oil, and sesame oil have considerable non-linear optical responses. Estimated values for both parameters\({n_2}\)and\({\chi ^{\left( 3 \right)}}\)for these oils are compared to reported values for some oils in Table 2. The measured values for \({n_2}\)and \({\chi ^{\left( 3 \right)}}\) are found to be in the orders of (\({10^{ - 6}}\,c{m^2}/W\)) and (\({10^{ - 5}}esu\)), respectively, which are comparable with the values of thermally induced non-linear optical parameters expected for non-linear materials (Boyd 2020).
3.3 Authentication of vegetable oils based on SSPM method
As mentioned above, to evaluate the authenticity of various vegetable oils based on their non-linear optical properties, we produced adulterated oil samples by diluting the original oils with a cheaper oil (sunflower oil) in five different dilution rates: 1:0, 2:1, 1:1, 1:2, and 0:1. The diffraction pattern of pure sample of sunflower oil is shown in Fig. 4(d). At maximum laser intensity, only two rings are observable. This could be due to the low light absorption (\(\alpha =0.126\,c{m^{ - 1}}\)) and thermal effect generation in sunflower oil.
For studying the non-linear optical behavior of all diluted samples (as adulterated oils) at various dilution rates, the diffraction ring patterns were recorded for the adulterated oil samples using the same experimental setup. Figure 6 displays the laser beam's diffraction patterns after passing through samples of dilution rates at maximum laser power. Diffraction rings appear more regularly in original samples (oils) than in diluted oils, and the number of rings decreases as the concentration of original oils decreases. We found that adding sunflower oil to initial oils results in a reduction in the density of the number of absorbing species and, thus, a decrease in the amount of absorbed energy by the samples (The UV-Visible absorption spectra of oils at all concentrations are shown in Fig. 3). As a result of such a reduction in light absorption in diluted oils, the thermal effect in the samples is reduced, and the phase difference also decreases. Hence, dilution-induced changes in the diffraction ring patterns result in a decrease in the number of rings for a given power and an increase in the threshold power, as shown in Fig. 7.
Figure 8 shows the required laser intensity to observe a certain number of rings, as well as the linear fit of the data. We see that the changes are linear and that the slope of the line decreases as the portion of original oil decreases (the adulteration ratio increases), thereby reducing the non-linear behavior of the samples. Calculated values of the non-linear optical index \({n_2}\)and non-linear optical susceptibility\({\chi ^{\left( 3 \right)}}\)listed in Table 3 indicate that undiluted oils have greater non-linear optical properties than adulterated oils. In other words, the values closely correlate to samples' adulteration levels.
Spatial Self-Phase Modulation (SSPM) is a non-linear optical effect that can be used to investigate the non-linear optical properties of materials. In this work, for the first time, we investigated the non-linear optical response of three vegetable oils (avocado seed oil, cherry seed oil, and sesame oil) by using the SSPM technique with a continuous laser beam. The results show that the vegetable oil samples have a noticeable non-linear optical response. In addition, studying the non-linear behavior of vegetable oils allows us to evaluate diluted vegetable oils' adulteration by adding cheaper oil. It is suggested that the investigation of non-linear optical properties of vegetable oils using the SSPM technique could be used to authenticate and determine adulteration for these materials as an economical, fast, cheap, accurate, and portable technique. Also, the findings of this study suggest that vegetable oils might have some application, especially in optical switching and photonic devices, based on their non-linear optical characteristics.
Authors’ contributions All authors contributed to the concept and design of the study. Data preparation, collection and analysis were performed by all authors. All authors read and approved the final manuscript.
Conflict of Interest All authors declare that they have no conflict of interest.
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Funding No funding, grants or other support was received.
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Data availability All data generated or analyzed during this study are included in this published article
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Table 1: Measured nonlinear optical parameters of three vegetable oils using the SSPM technique
|
Sample |
|
|
|
|
|
Avocado seed oil |
5.933 |
0.096 |
1.68 |
9.18 |
|
Cherry seed oil |
3.55 |
0.175 |
3.06 |
16.8 |
|
Sesame oil |
13.12 |
0.034 |
0.6 |
3.28 |
Table 2: The order of magnitude of measured nonlinear optical parameters for oils
*EVOO: extravirgin olive oil, EVSO: extra virgin sesame oil, ERLO: extra refined linseed oil, and VAVO: virgin avocado oil
Table 3: Measured nonlinear optical parameters for different oil dilution rates using the SSPM technique
|
Sample |
|
|
|
|
|
Avocado seed oil |
|
|
|
|
|
1:0 |
5.933 |
0.096 |
1.68 |
9.18 |
|
2:1 |
7.897 |
0.071 |
1.24 |
6.8 |
|
1:1 |
10.057 |
0.064 |
1.12 |
6.11 |
|
1:2 |
11.852 |
0.051 |
0.89 |
4.88 |
|
Cherry seed oil |
|
|
|
|
|
1:0 |
3.55 |
0.175 |
3.06 |
16.8 |
|
2:1 |
4.149 |
0.163 |
2.86 |
15.6 |
|
1:1 |
4.858 |
0.126 |
2.2 |
12.0 |
|
1:2 |
5.405 |
0.113 |
1.97 |
10.8 |
|
Sesame oil |
|
|
|
|
|
1:0 |
13.12 |
0.034 |
0.6 |
3.28 |
|
2:1 |
16.452 |
0.031 |
0.54 |
2.95 |
|
1:1 |
17.732 |
0.026 |
0.45 |
2.45 |
|
1:2 |
19.9 |
0.025 |
0.44 |
2.39 |
No competing interests reported.