1. INTRODUCTION:

Corylus avellana is commonly known as Hazelnut, the oil is derived from the hazelnut tree, and it belongs to the birch family Betulaceae.^1-2 This plant oil is commonly found in regions such as the Mediterranean, the Middle East deserts, South Asia, and the Far East. The oil content is around 50-75 %. The hazelnut oil contained high amounts of unsaturated fatty acid. oleic (18:1, 68.8–78.6%) and linoleic (18:2, 14.2–23.3%) acids, linolenic (18:3, 0.1–0.2%) acids. Oleic acid was the predominant fatty acid, and oleic acid and linoleic acid comprised more than 90% of the fatty acid composition.^3-5

Hazelnut oil is prized for its rich composition, making it valuable in both culinary and cosmetic applications. In food, it serves as a flavourful and nutritious ingredient, while in cosmetics, it offers various skincare benefits^6-8. Composed primarily of healthy monounsaturated fats, hazelnut oil is rich in oleic acid, which contributes to its stability and resistance to oxidation. This makes it suitable for cooking and baking, adding a nutty flavour to dishes while imparting beneficial nutrients. In addition to fats, hazelnut oil contains vitamin E, an antioxidant that helps protect cells from damage caused by free radicals. This makes it beneficial for both food preservation and skincare. In cosmetics, vitamin E nourishes the skin, promotes elasticity, and helps reduce the signs of aging.^9-10

Hazelnut oil's lightweight texture and non-greasy feel make it well-suited for all skin types in cosmetic applications. It moisturizes and softens the skin without clogging pores, making it ideal for facial oils, moisturizers, and serums. Its antioxidant properties help protect the skin from environmental damage, while its astringent qualities can tone and tighten the skin, reducing the appearance of pores and improving texture.^11-12 Formulating hazelnut oil into a clear and transparent liquid form is crucial, particularly for studying its ability to use in cosmetic for skin care application. Microemulsion emerges as a promising approach to achieve this. Microemulsions are known for their ability to enhance the solubility of poorly water-soluble substances. They consist of a thermodynamically stable dispersion system. The ideal microemulsion size must be below 100 nm, ensuring transparency and facilitating microscopic observation.^13-14 Various types of microemulsions, including oil-in-water, water-in-oil, and bicontinuous, offer potential formulations for hazelnut oil^15-16. One viable strategy for preparing hazelnut oil microemulsions involves utilizing a combination of castor oil-based surfactants, without the need for a co-solvent. These formulations hold promise for advancing research on hazelnut oil application in cosmetic Hair care and skin care.^17-23

2. MATERIALS AND METHODS:

2.1 Materials:

The hazelnut oil was procured from a local market. The emulsifier, castor oil ethoxylate, was generously provided as a gift by Rossari Biotech Ltd. All reagents employed in the experiment were of analytical grade and utilized without further purification.

2.2 Methods:

2.2.1 Characterization of Hazelnut oil:

Hazelnut oil was characterized by observing Appearance specific gravity, Acid value, Peroxide content, Iodine value, Saponification value surface tension.

2.2.2 Characterization of Emulsifier:

Castor oil ethoxylate was characterized by observing pH, specific gravity, HLB, Cloud point, surface tension.

2.2.3 Preparation of Microemulsions

Pseudo-ternary phase diagrams for hazelnut oil were constructed using water titration at ambient temperature. For each system, castor oil ethoxylate was employed as the surfactant. The oil and emulsifier were combined in varying weight ratios (ranging from 0:10 to 10:0) with different hydrophilic-lipophilic balance (HLB) values. Deionized water was gradually titrated into these mixtures until the onset of turbidity. The water consumption, expressed as a percentage of the total formulation content, along with the corresponding oil and emulsifier percentages, enabled the construction of the phase diagrams. Subsequently, microemulsion formulations were selected from the identified microemulsion regions for further investigation

2.2.4 Characterization of the Microemulsions:

1. Microemulsions

2. The homogeneity, clarity, and optical transparency of microemulsions were studied by visual examination on a black background at room temperature.

3. Ph- The pH levels of different formulations were assessed at ambient temperature (25 °C) using a pH meter (Equiptronics microcontroller pH meter model EQ 621 India).

4. Particle size

5. The evaluation the particle size of the microemulsion formulations were analysed using a Mastersizer 3000

5.Hydro (Malvern Panalytical, Worcestershire, UK) at room temperature.

6. Electrical conductivity

7. The optimized microemulsion's electrical conductivity was assessed concurrently at 25°C using a conductivity meter LMCM20 (Labman Scientific Instruments Pvt. Ltd, India). The phase system of the optimized microemulsion was determined based on its electrical conductivity

8. Physicochemical stability tests

9. The physicochemical stability test was performed at room temperature for 30 days. The particle size, conductivity, pH, viscosity, and Centrifugation stability test at 3,000 rpm for 30 minutes stability of the microemulsion thermodynamic stability of microemulsions were evaluated.

3. RESULTS:

3.1 Characterization of Hazelnut oil

Table -1: - Physicochemical parameters of hazelnut oil

Sr.no	Parameter	Value
1	Physical appearance	Clear Yellow liquid
2	Specific Gravity	0.916
3	Acid Value	0.2
4	Iodine Value	92
5	Peroxide Value	2.2
6	Saponification value	176
7	Surface tension	32.5

3.2 Characterization of Emulsifier:

Table -2: - Physicochemical parameters of Castor oil ethoxylate

Sr.no	Parameter	Castor oil ethoxylate 20 moles	Castor oil ethoxylate 30 moles	Castor oil ethoxylate 40 moles
1	Physical appearance	Clear Viscous liquid	Clear Viscous liquid	Clear Viscous liquid
2	Specific Gravity	1.062	1.061	1.064
3	pH (5 % solution)	7.1	7.3	6.90
4	HLB value	9.7	11.7	13.1
5	Surface tension	45.3	43.1	39.5
6	Moisture content	0.23	0.31	0.16
7	Saponification value	93	69	59

3.3 Construction of Phase Diagram for microemulsion:

The microemulsion formulation was prepared by blending hazelnut oil with the surfactant. To determine the optimal ratio, various moles of castor oil ethoxylate (20, 30, and 40) were mixed with the oil, followed by gentle agitation with distilled water. Fig.1,2, and 3 depict the pseudo-ternary phase diagram of the investigated system, encompassing hazelnut oil, castor oil ethoxylated emulsifier, and water. The shaded area represents the formation of the microemulsion system, observed at room temperature. Analysis of the pseudo phase diagrams revealed that the largest microemulsion zone occurred with the surfactant castor oil ethoxylated 30 moles, without a co-solvent, corresponding to an HLB value of 11.7. Variations in microemulsion zones were noted for HLB values of 9.7, 11.7, and 13.1.Phase studies indicated that the maximum water incorporation into the microemulsion system was achieved at an HLB of 11.7. Increased water content and reduced surfactant and oil content facilitated greater solubilization of the active ingredient, resulting in a less viscous and transparent microemulsion—a distinct advantage. The developed microemulsion, comprising hazelnut oil, castor oil ethoxylate, and water, exhibited transparency with increased water content and decreased surfactant and oil content. Initially clear, the microemulsion transitioned to a transparent, flowable state at increased water content and the optimal HLB of 11.7. Castor oil ethoxylated 30 moles demonstrated the widest area of emulsification, thus was chosen for further optimization.

Figure-1. Hazelnut oil microemulsion with HLB 9.7 castor oil ethoxylate 20 moles

Figure-2. Hazelnut oil microemulsion with HLB 11.7 castor oil ethoxylate 30 moles

Figure-3. Hazelnut Oil Microemulsion With Hlb 13.1 Castor Oil Ethoxylate 40 Moles

Table -3. Hazelnut oil microemulsion using castor oil ethoxylate

Sr.no	Formulation	Surfactant	Surfactant	Oil	Water	Total
Sr.no	Formulation	Castor oil ethoxylate	Percentage	Percentage	Percentage
1	CO 20-1	CO 20	36.00	4.00	60.00	100
2	CO 20-2	CO 20	23.74	4.19	72.07	100
3	CO30-1	CO 30	29.23	1.54	69.23	100
4	CO30-2	CO 30	27.69	3.08	69.23	100
5	CO30-3	CO 30	73.18	8.13	18.69	100
6	CO30-4	CO 30	66.96	16.74	16.30	100
7	CO40-1	CO 40	19	1	80	100
8	CO40-2	CO 40	18	2	80	100

Table -4: - Hazelnut oil microemulsion physical parameter

Sr.no	Formulation	Microemulsion	pH	Density	Viscosity	Conductivity	Particle size
Sr.no	Formulation	Type	pH	Kg/m3	CPS	mS/m	nm
1	CO 20-1	O/W	7.68	1.0357	32	185.5	163
2	CO 20-2	O/W	7.61	1.105	27	179.2	177
3	CO30-1	O/W	6.96	1.0201	37.8	189.3	130
4	CO30-2	O/W	6.66	1.0121	22.8	173	149
5	CO30-3	W/O	7.04	1.0708	148	31	67
6	CO30-4	W/O	7.5	1.051	124	14.3	132
7	CO40-1	O/W	7.1	0.9808	18	246	167
8	CO40-2	O/W	6.93	0.9896	23	248	367

Table -5: - Hazelnut oil microemulsion centrifuge stability

Sr.no	Formulation	Centrifuge stability Before	Centrifuge stability After 30 days
1	CO 20-1	No Separation	No Separation
2	CO 20-2	No Separation	No Separation
3	CO30-1	No Separation	No Separation
4	CO30-2	No Separation	No Separation
5	CO30-3	No Separation	No Separation
6	CO30-4	No Separation	No Separation
7	CO40-1	No Separation	No Separation
8	CO40-2	No Separation	No Separation

Figure 2 :- Physical appearance of Hazelnut oil microemulsion

4. DISCUSSION:

4.1. Phase diagram study of the hazelnut oil microemulsion system:

The selection of the optimum HLB (hydrophilic-lipophilic balance) value of 11.7 for the surfactant system was a crucial factor in achieving a stable and efficient microemulsion formulation with hazelnut oil. The HLB value represents the balance between the hydrophilic and lipophilic portions of the surfactant molecule, which plays a pivotal role in determining its emulsifying behavior and compatibility with the oil and water phases. In this study, the surfactant system investigated was castor oil ethoxylate with varying moles of ethoxylation (20, 30, and 40 moles). The HLB values corresponding to these surfactants were 9.7, 11.7, and 13.1, respectively. The data are shown in Figures 1, 2, and 3. Through extensive phase behavior studies and characterization, it was observed that the microemulsion region was most prominent and exhibited optimal properties at an HLB value of 11.7. The ternary phase diagram revealed that the microemulsion region was largest and most well-defined at the HLB of 11.7, indicating a higher solubilization capacity and broader compositional range for stable microemulsion formation. The solubilization capacity of the microemulsion system is directly related to the surfactant composition and its ability to solubilize the oil and water phases. It was observed that the castor oil ethoxylate with 30 moles of ethoxylation (HLB 11.7) demonstrated the highest solubilization capacity for hazelnut oil and water, as evidenced by the extensive microemulsion region in the phase diagram. Surfactants with lower or higher degrees of ethoxylation exhibited reduced solubilization capacities, leading to smaller microemulsion regions.

4.2. Particle Size &Stability:

The microemulsion formulation at HLB 11.7 exhibited the smallest droplet size of 67 nm, which is advantageous for improved solubility, bioavailability, and transparency. The microemulsion system at this HLB value demonstrated superior stability under centrifugal stress conditions, indicating its robustness and resistance to phase separation or coalescence. The optimized formulation produced transparent liquid masterpieces, which is a desirable characteristic for various applications, such as cosmetics and pharmaceutical formulations. The surfactant composition significantly influenced the droplet size and polydispersity of the microemulsions. The optimized formulation with castor oil ethoxylate (30 moles) at HLB 11.7 exhibited the smallest droplet size of 67 nm with a narrow size distribution. Surfactants with lower or higher degrees of ethoxylation (20 and 40 moles) resulted in larger droplet sizes and broader size distributions, potentially due to less efficient packing at the oil-water interface or decreased solubilization capacity. The stability of microemulsions is crucial for their practical applications. The study revealed that the microemulsion formulation with castor oil ethoxylate (30 moles) at HLB 11.7 displayed superior stability under centrifugal stress conditions. This stability can be attributed to the optimal balance between the hydrophilic and lipophilic components of the surfactant, minimizing the tendency for phase separation or coalescence. Surfactants with lower or higher degrees of ethoxylation may have exhibited reduced stability due to imbalances in their hydrophilic-lipophilic properties.

5. CONCLUSION:

Finally, this study allowed the preparation of a novel microemulsion system with hazelnut oil as the selected oil phase. The study confirmed the microemulsion range of surfactants by preparing groundical preparation and thorough analysis of droplets size provides optimised micro-emulsion formulation with respect to all the work parameters and guarantees its successful industrial application. The optimised formula having an HLB (hydrophilic-lipophilic balance of surfactant) value = 11.7 was observed to have smallest droplet size (67 nm) and maximum interphase inverted micellar region exhibiting high stability under centrifugation stress conditions. A comprehensive phase diagram was successfully constructed in order to elucidate the complex relationship between the individual components and their combinations. The prepared non-ionic surfactant formulation consists of hazelnut oil which can be utilised in various areas of application, such as pharmaceuticals, cosmetics, food and beyond. It can be stated that the prepared hazelnut oil-based microemulsion resulting from this study can be used as a stabiliser in the pharmaceutical, cosmetic and food industry, especially in the case of unstable or organoleptically harsh poorly soluble lipophilic natural products.

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Received on 24.04.2024 Modified on 03.05.2024

Research J. Science and Tech. 2024; 16(2):119-124.

DOI: 10.52711/2349-2988.2024.00018