THAI NGUYEN UNIVERSITIES UNIVERSITY OF AGRICULTURE AND FORESTRY DANG MAI HUONG A STUDY ON THE PRODUCTION OF SOAP BASED ON TANGERINE PEEL ESSENTIAL OILS BACHELOR THESIS Thai Nguyen, 2023.
INTRODUCTION
Research’s objectives
There were 04 specific objectives of this study:
+ Distill and retrieve the essential oils from Cao Bang Tangerine peels + Investigate the production process for a soap product incorporated with the Tangerine essential oils
+ Evaluate the output product in terms of sensorial properties and storability
+ Design the package for the soap product and execute calculations for commercialization
This study was conducted based on the following hypotheses and questions: + Question 1: What are the optimal conditions for extracting tangerine peel essential oil using industrial scale methods?
This question led to many hypotheses regarding the suitable methods for essential oil extraction in this study Hydro-distillation and cold press were among the most prominent considerations In addition, there were hypotheses regarding the default points of research for finding optimal factors
+ Question 2: Is tangerine peel essential oil suitable for making a soap product? Question 2 also referred to the methods for making soap and the hypothesis of suitability for incorporating tangerine peel essential oil to a soap formula.
Limitations
Despite the utmost effort of the implementer as well as the supervisors, this study remains with few limitations that require much help, comments, and recommendations from the instructors, lecturers, and experts in the field Here are the most eminent limitations that the implementation of this study encountered:
+ Research capabilities: The implementer had studied both theoretical foundations and realistic foundations before conducting research protocols However, there are still limitations that may impede accuracy or further achievement of this project
+ Differences in approaching: The approaches that this study had selected possess many differences compared to many methods used by many studies in the same fields That is why there was a lack of comparative means, which could reduce the objectivity of the findings from this study
+ Variable instruments: Instruments used in this study also affected the results and also reduced the range of comparisons with other articles The depreciation of the instruments should also be considered in limitations of not just this study but also many others
+ Risk management: The study had employed a few methods to manage the risks while implementing research However, it is difficult to achieve an absolute result and there was definitely likelihood of error
+ Essential oils: Volatile substances within an organic body that can be easily extracted via high-temperature extraction
+ Saponification: A chemical reaction between a fatty acid and an alkaline that would replace a H atom in the COOH radical by the ion form of the alkaline.
LITERATURE REVIEW
Overview of soap products
In the Vietnamese standards, “Soap” refers to many different types of product lines This study was focusing on the soap bar for personal care (toilet soap – according to TCVN 2224:1991) In terms of chemistry, “soap” is a result of the saponification process occurring due to the reaction between fat or oil and a strong alkali like Sodium Hydroxide (NaOH) or Potassium Hydroxide (KOH) The reaction is showed in Figure 2.1 below:
Figure 2.1 The saponification reaction between a fatty molecule and an alkali
Based on the reaction in Figure 2.1, it is clear that the nature of the saponification process is a simple reaction between an ester and an alkali, creating a salt and an alcohol (glycerol) The salt has the characteristics of a detergent when it can cover the dirty molecule while also exerting hydrophilic properties, creating the rinsing effect with the flow of water to remove the dirt Furthermore, according to the study of Giuliano & Rybak (2015) on the anti-microbial mechanism of soap products, the soap molecules can also disrupt the cell membrane of microbes
The secondary product of this process is glycerol According to Milani & Sparavigna (2017), it is commonly used in skincare and cosmetic products due to its excellent moisturizing properties It helps to attract and retain moisture in the skin, keeping it hydrated and supple Additionally, glycerol has humectant properties, meaning it can draw moisture from the air, further enhancing its moisturizing effects (Azelee et al., 2019) Beyond skincare, glycerol is also utilized in food and pharmaceutical industries, as a solvent, sweetener, and preservative Its wide range of applications makes glycerol a valuable and multifunctional compound
The two compulsory ingredients for making soap are the fat (oil) and the alkali to take part in saponification There are also other ingredients employed for the process Specifically:
+ Theoretically, any type of fat or oil can be usable to make soap However, each type exerts distinct properties, making only a few suitable for the demand of customers in the market nowadays In the soap industry, especially in the Vietnamese market, there are 02 types of popular oils used for soap: coconut oil and palm oil The study of Boateng et al in 2016 compared these two types of oils in terms of soap making potential and showed that the coconut In addition, the study of Félix et al (2017) had indicated the use of animal fats, sesame oil, olive oil, and even the oil wasted from cooking in soap production
+ Regarding the alkali, there are 02 possible types: Potassium Hydroxide (KOH) and Sodium Hydroxide (NaOH) The difference in terms of saponification value (the saponification efficacy and the resulting salt) makes KOH a suitable alkali for liquid soap while NaOH is often used for soap bars a (Sousa et al., 2010) In the past, these two alkali for making soap were obtained from a process called leaching According to the description of Tukey Jr (1970), leaching involves the use of water to extract water-soluble compounds from the ash of hardwood trees like birch and oak These trees possess potassium and sodium carbonates, which create alkali in water Nevertheless, this technique is outdated Nowadays, most soap making manufacturers employ industrially-produced NaOH to make hand soap bars This compound can also be easily purchased on many platforms + Water is actually a mandatory ingredient for making soap It is responsible for dissolving the alkali According to the book “Basic soap making” of Letcavage (2009), the amount of water affects significantly on the formation and the texture of soap bars Furthermore, it also creates a medium for the addition of other ingredients
+ Additives and other ingredients have gradually become an essential part of soap making According to the books of Letcavage (2009) and Pierce (2013) on the recipe of soap making, the additives are often fragrances, colorants, exfoliants moisturizers, and preservatives In the studies of Rios (2016) and Dhakad et al (2018), which incorporated herbal essential oils into soap making, it was showed that essential oils often played roles as fragrances Some also exert properties of colorants or even provide anti-oxidation properties
2.1.3 The effects of soap products
Personal care soap products play a crucial role in maintaining hygiene and promoting overall well-being The article of Aiello et al (2008) on hand soap products showed that from a hygienic perspective, these products effectively remove dirt, oil, sweat, and impurities from the skin's surface By lathering and rinsing with soap, the natural oils and debris accumulated throughout the day are gently washed away, leaving the skin clean and refreshed This cleansing action helps to reduce the buildup of bacteria, germs, and pollutants, thereby minimizing the risk of infections and skin-related issues Regular use of soap also aids in the prevention of body odor, ensuring that individuals feel fresh and confident throughout the day
Beyond the hygienic benefits, personal care soap products offer aesthetic effects that contribute to an individual's overall appearance and self-care routine Soap formulations often incorporate ingredients like moisturizers, vitamins, and botanical extracts, providing nourishment and hydration to the skin These ingredients help to maintain the skin's natural moisture balance, keeping it soft, smooth, and supple Soap products designed for specific skin types or concerns, such as acne-prone or sensitive skin, offer targeted benefits, assisting in the management of these conditions Additionally, scented soap variants add a sensory delight to the bathing experience, with a wide array of fragrances available to suit personal preferences These have been reflected well in the study of McGhee et al in 2019 on the roles of hand soap amidst the COVID 19 pandemic
Regular use of personal care soap products promotes skin health and enhances the aesthetics of the body (McGhee et al., 2019; Dover et al., 2020) Clean, well- maintained skin contributes to a positive self-image and boosts self-confidence The tactile experience of lathering soap on the body, combined with the fresh and pleasant fragrances, can also evoke a sense of relaxation and rejuvenation, turning a simple daily task into a moment of self-care It is important, however, to select soap products that are suitable for individual skin types and to follow proper cleansing routines, as excessive or improper use may lead to dryness or irritation.
Soap production techniques
2.2.1.1 Hot process and cold process
The cold process is considered the fundamental protocols of soap making It covers from the input ingredients to the output product First, the process requires the mixing between the alkali and the water Afterward, the alkali solution is poured in the oil and the batch is stirred to achieve the “trace” state (thickening)
At this state, the other ingredients and additives are added and the stirring continues to evenly distribute the ingredients Subsequently, the mixture is poured into molds, covered with an insulation layer and let sit for about 1 – 2 days for the soap to solidify Finally, the soap is cut into bars and the bars are cured for a few weeks for the soap to fully hardened and dried During the blending of materials and saponification process, precautionary practices such as wearing a goggle or use gloves are required as the alkali solution is often caustic materials (Eroglu et al., 2012).This process has been proved to be suitable for small scale production like households, individuals, and laboratory purposes (Maotsela et al., 2019; Ott, 2021) The study of Maotsela et al even showed that the cold process can potentially utilize wasted cooking oil and tallow to produce toilet soap However, the inherent disadvantage of the cold process is that it takes too much time for the soap to be cured (30 days) Furthermore, there is a risk of contamination as during the drying and curing process, the soap is exposed to the environment
The hot process is considered a solution for the weakness of the cold process Most of the steps remain similar to the cold process but heat is applied during saponification and curing, making the production faster Nevertheless, the hot process contains a risk of damaging additives as it involves high temperatures (Furtado & May, 2004) Furthermore, the hot process also requires more in terms of equipment and techniques
2.2.1.2 Melt & pour and re-batching process
Melt & pour and re-batching are the two techniques of soap making that employ pre-made soap bases or soap bars In other words, these two techniques do not require saponification In both techniques, the pre-made soap is melted to a liquid state and additional ingredients are added to the solution The operation is relatively simple with an advantage of avoiding the saponification process, which is relatively difficult to control and can be risky The difference between these two soap making method is that melt & pour employs pre-made soap bases (Browning, 2002; Saxton et al., 2013) As a result, this technique highly facilitates customization for the soap and is often used to investigate the compatible of preservatives and other ingredients like herbal extracts and essential oil On the other hand, re-batching uses pre-made soap bars instead of bases, according to Melina Coss with the book about handmade soap (2016) Therefore, the newly formed soap still contains properties of the previous soap, creating exotic colors and marbling effects on the soap
Soap production on industrial scales often involves a large volume of ingredients in one batch as well as the automation required for lowering production costs Depending on the desired type of soap or, input ingredients, available facilities and instruments, and even regional cultures, the production chain may vary significantly among different manufacturers Nevertheless, the general soap making process can be summarized via Figure 2.2 below:
Figure 2.2 Industrial production process of soap bar products
It can be seen that the production process on industrial scales is an adaptation from the hot process of soap making.
Tangerine peel
Tangerine (Quýt, Citrus reticulata) is a popular fruit in Vietnam and many Asian countries like China and India As indicated in the scientific name, Tangerine belongs to the Citrus family with notable members like Orange and Lemon The pulp of this fruit is delicious and offers many health benefits like anti-oxidation and immunology enhancement (Yu et al., 2014) The season for harvesting often lasts for a few months from November The consumption market of Tangerine in Vietnam is considerably large when according to the Department of Statistics, the market had consumed over 10,000 tons of the fruit in 2021
Nevertheless, the subject of interest in this study is not the pulp of Tangerine but the peel According to the study of Singh et al (2020), the peel of Tangerine resembles many other types of Citrus fruit peel It has a diverse profile of phenolic compounds and flavonoids, which exert many beneficial bioactivities like anti-oxidation, anti-inflammation, and cardiovascular supporting effects More remarkably, this is a rich source of essential oils The studies of Johnson et al (2013) and Denkova-Kostova et al (2021) on the constituents of Tangerine peel essential oils showed that the main volatile compounds included D-limonene and cis-cinnamaldehyde as the two main constituents, along with some other minor compounds like α-pinene and β-pinene
2.3.2 Beneficial effects of mandarin peel essential oil
Tangerine peel essential oil, derived from the outer peel of Citrus reticulata, offers a range of beneficial effects that make it a popular choice in aromatherapy and skincare With its sweet, citrusy aroma and diverse therapeutic properties,
Tangerine peel essential oil provides numerous advantages for physical, mental, and emotional well-being First, Tangerine peel essential oil possesses uplifting and calming properties (Mirghafourvand et al., 2016; Kwangjai et al., 2021) The refreshing scent has been shown to promote relaxation, reduce stress, and alleviate anxiety Inhaling the aroma of this oil can help create a sense of tranquility and improve mood, making it a valuable tool for managing stress and promoting overall mental well-being Tangerine peel essential oil is renowned for its skin-enhancing properties (Kammoun Bejar et al., 2011; Gbaj et al., 2019) It exhibits excellent cleansing and purifying qualities, making it a popular ingredient in skincare products The oil helps to promote a clear, healthy complexion by minimizing the appearance of blemishes and supporting a balanced skin tone It also possesses mild astringent properties that can help tighten the skin and reduce the appearance of pores Additionally, the antimicrobial properties of Tangerine peel essential oil further contribute to its beneficial effects (Kirbaşlar et al., 2009) It possesses natural antibacterial and antifungal properties that can help combat harmful microorganisms Incorporating this oil into personal care products or diffusing it in the air can help purify the environment and support a clean, germ-free atmosphere It is obvious that these benefits of Tangerine peel essential oils are compatible to those that a personal care product like hand soap would provide to its customers
There are numerous methods of extracting volatile compounds out of a plant The most notable ones include hydro-distillation, enfleurage, and cold pressing The details of these methods are as follows:
+ Hydro-distillation is a traditional method used to extract essential oils from plant materials According to the study of Golmakani & Rezaei in
2008 on the method, it involves the use of water and heat to generate steam, which passes through the plant material, carrying the volatile essential oil compounds The steam is then condensed, separating the essential oil from the water, resulting in the final product
+ Enfleurage is an ancient technique used to extract fragrant compounds from delicate flowers that are too sensitive for traditional extraction methods (Soe’eib et al., 2017) It involves placing flower petals on a layer of fat, such as animal fat or vegetable oil, allowing the volatile compounds to infuse into the fat over time The fat is then repeatedly replenished with fresh petals until saturation Finally, the fragrant fat is washed with alcohol to separate the essential oil, resulting in a highly concentrated floral extract Enfleurage is a labor-intensive process and is less commonly used today compared to other extraction methods
+ According to “a review on cold press in oil extraction” of Cakaloglu et al (2018), cold pressing is a method used to extract essential oils from citrus fruits, such as oranges, lemons, or grapefruits It involves mechanically pressing or squeezing the outer rind of the fruit to release the essential oil The fruit is typically first punctured or scored to facilitate the oil's release This method does not involve heat or solvents, allowing for a more natural extraction process The resulting essential oil is typically highly aromatic and retains the characteristic scent of the citrus fruit Cold pressing is commonly used for obtaining citrus essential oils due to its simplicity and ability to preserve the fragrance of the fruits
There are also a few other techniques used for extracting essential oils such as solvent extraction, super-critical fluid extraction, and maceration.
Status of research on the interested subjects
2.4.1 Research status on the world scale
The research status on extracting essential oils in the world has reached advanced points for many different types of plant, including citrus relatives such as Tangerine Particularly, the studies of Xiong & Chen (2020) and Rajput et al (2022) had extracted essential oils from Tangerine from China and India, respectively, using super-critical CO2 as the solvent They both showed the potency of this technique as the temperature needed for the operation as well as the time is significantly lower compared to other techniques like solvent extraction and hydro-distillation The two studies also succeeded in identifying the composition of the essential oils and the bioactivities that the oils offer Supercritical fluid extraction is also favored by many other studies that extract Tangerine essential oils and characterize the extract (Chen & Huang, 2016; Rosa et al., 2019)
Other techniques also showed great promises in Tangerine peel extraction studies In Mexico, Dugo et al (2005) characterized the Tangerine essential oils using cold pressing for extraction The extract was showed to have a higher content of limonene, while γ-Terpinene, myrcene and α-pinene were the other most abundant hydrocarbons Zhao et al (2022) employed hydro-distillation and needed a material – solvent ratio of 1:17 g/ml, room temperature, and an extraction time of 4 hours to yield the maximum amount of essential oils out of Tangerine peel Bustamante et al (2016) extracted the essential oils using hydro- distillation with the support of microwave and pressure The operation included a material – solvent ratio of 1:1.5 g/ml and the extraction time of only 20 minutes, greatly reduced compared to the conventional hydro-distillation in the study of Zhao et al (2022) Recently, the study of Rashed et al (2023) had successfully employed a complex two-phase extraction method with the assistance of not just microwave but also enzyme treatment The yield was significantly high with large size of D-limonene detected in the extract as well as the optimal creaming index and minimal degradation rate
2.4.2 Research status on the Vietnamese scale
In Vietnam, scientific research on the extraction of Tangerine essential oils escalated in the recent 5 years with the domination of hydro-distillation The study of Trần et al (2019) study the effect of hydro-distillation and extracted essential oils composed of limonene (97.655%), followed by β-Myrcene (1.395%), 1R-α-Pinene (0.561%), L-β-pinene (0.264%), and Sabinene (0.126%) The operation included a material – solvent ratio of 1 g/4 ml of water, a temperature of 110 o C – 120 o C, and an extraction time of 150 minutes In the next year, Ngô et al (2020) utilize the support of microwaves in the hydro-distillation technique to extract Tangerine essential oils The results showed a great influence of 600 W microwave assistance when the material – solvent ratio was only 1 g/3 ml of water and the extraction time was only 55 minutes Through gas chromatography – mass spectrometry, the essential oils extracted from this study was showed to resemble the components in the study of Trần et al with limonene
(97.688%), sabinene (0.12%), β-myrcene (1.394%), (-)-β-pinene (0.273%), and 1R-α- pinene (0.525%) These studies have laid foundations for some Tangerine essential oil products on the Vietnamese market (Figure 2.3)
2.4.3 Status of the soap market
Recently, a new brand of organic-based soap products has emerged in the Vietnamese market The brand is called “sinh dược” with many different types of hand soap that derive natural extracts, such as cinnamon (Cinnamonum verum), bitter melon (Mormodica charantia), and turmeric (Curcuma longa) These products received much positive feedback from customers and often recorded high sales every month The brand has also been expanding to other product lines such as bath salts, fragrant essential oils, and organic-based detergents In addition to “sinh dược”, there are also few minor brands that offer organic soaps such as bamboo ash-based hand soap and sesame-based hand soap Nevertheless, the market has not recorded the introduction of any Tangerine peel essential oil- based soap product.
Assessment on literature review
+ The nature of soap production is relatively simple with only the saponification reaction between fat and an alkali The products of such a process including glycerol and soap are utilizable in many ways, making a foundation for research and development The soap product line is also in a high demand from the market, especially in Vietnam Along with the increasing need for organic-based products, this is a huge opportunity for a new type of product
+ The materials for soap making are not difficult to reach with primarily many options for oils and even the alkali solution Additional ingredients and various types of preservatives have also been proved feasible Furthermore, there have also been many studies regarding the production process of soap products with comprehensible operation
+ Tangerine peel is a relatively abundant material in particularly the Vietnamese market The essential oil of this material has many beneficial effects on the skin, which are compatible to the purposes of a hand soap products Furthermore, the research status has showed the feasibility of combining herbal essential oil in personal care products like hand soap
+ The realistic market of the hand soap product line remains limited in terms of options and variations for customers Furthermore, organic-based products are still considered a foreign term at supermarkets and grocery stores There is no soap products that derive the citrus essential oils, not to mention Tangerine peel’s alone Therefore, this is an opportunity for the development of a soap product based on Tangerine peel essential oil.
METHODOLOGY
The Tangerine was collected from Cao Bang Province The pulp was then separated from the peel Subsequently, the peel was washed in tap water to remove foreign materials on the skin Finally, the peel was stored in cold temperatures (0 – 5 o C) or cut into small pieces (3 cm x 1 cm) for immediate essential oil extraction
Figure 3.1 Cao Bang Tangerine and the peel
The oils to make soap included coconut oil, palm oil, and olive oil, which were purchased from local markets As these items are vulnerable to oxidation, they were stored in carefully sealed bottles at a cool and dry place, avoiding direct sunlight
The instruments used for the implementation of this study were listed in the following Table 3.1
Table Error! Use the Home tab to apply 0 to the text that you want to appear here Instruments and laboratory equipment used in the study
5 30-cm glass coil heat exchanger China
8 Borosilicate glass measuring cup China
In addition, the study also employed some plastic containers and other laboratory instruments like glass stirrer, glass test tubes, filtering paper, etc
Commented [LC2]: Neus đã để bên trên figure ở dưới phần này tabnle cũng follow như thế nhé
The chemicals used for the implementation of this study were listed in the following Table 3.2
Table Error! Use the Home tab to apply 0 to the text that you want to appear here Chemicals used in the study
No Chemical name Chemical formula Origin
3 Sodium Sulfide Na2SO4 China
6 Acetic Acid CH3COOH China
The study was conducted on a laboratory scale located in the Faculty of Biotechnology – Food Technology – Thai Nguyen University of Agriculture and Forestry, Thai Nguyen City, Vietnam
There were 04 research contents in this study:
Content 1: Study the optimal conditions for the extraction of Tangerine peel essential oil This study was to:
- Determine the optimal material – water ratio
- Determine the optimal concentration of NaCl in the water
- Determine the optimal temperature for distillation
- Determine the optimal distillation time
Content 2: Study the conditions and the ingredients for the soap production process, this content included:
- Determine the appropriate type of fatty oil for saponification
- Determine the appropriate proportion of the added essential oil
- Determine the appropriate additives and proportion
Content 3: Investigate the quality of the output essential oil-based soap This content consisted of the headlines in TCVN 2224:1991
Content 4: Finalize the production process of the essential oil-based soap In this content, there were 02 activities:
- Complete the production process of the soap
- Calculate the expected cost and price for a soap unit
The study employed the Hydro-distillation method for extracting the essential oil out of Tangerine peels (Bustamante et al., 2016) This method uses water as the solvent, which ensure the safety of the extract for consumption or direct usage on the human body The costs for extraction using this way are also more affordable Furthermore, hydro-distillation is applicable on industrial scale The operation of the hydro-distillation technique is relatively simple The ingredients (Tangerine peel) was submerged in salted water for 2 hours The ratio between the water and the ingredients was fixed Afterward, the mixture was installed in a pressure cooker to initiate distillation at a certain temperature and for a certain amount of time After condensing the vapor coming from distillation, the liquid was separated using a separating funnel to achieve the essential oil
Subsequently, the raw oil was purified using Na2SO4 5% The purified oil was obtained after filtering the salt and all the sediments resulting from the previous step All the process can be summarized in Figure 3.2 as follows:
Figure 3.2 The cold process of hydro-distillation for extracting essential oil
Based on such operation, the study had set 04 adjustable parameters including the material – water ratio, the concentration of NaCl, the distillation temperature, and the distillation time Preliminary tests had given the default conditions of material – water ratio of 1:3 (v/w), the NaCl concentration of 1%, the temperature of 110 o C, and the time of 90 minutes The 04 parameters for optimization as well as the investigated range are showed below:
+ The ratio between the material (Tangerine peel) and water:
Table Error! Use the Home tab to apply 0 to the text that you want to appear here The investigated points of material – water ratios for Tangerine peel essential oil extraction Formula Material – water ratio (v/w)
+ The concentration of NaCl in the water:
Table Error! Use the Home tab to apply 0 to the text that you want to appear here The investigated points of salt concentration in the water for Tangerine peel essential oil extraction Formula NaCl concentration
Table Error! Use the Home tab to apply 0 to the text that you want to appear here The investigated points of extraction temperature for Tangerine peel essential oil extraction Formula Temperature
Table Error! Use the Home tab to apply 0 to the text that you want to appear here The investigated points of extraction time for Tangerine peel essential oil extraction Formula Material – water ratio (v/w)
After obtaining the optimal point of one parameter, that point was used in subsequent experiments All the experiments were carried out in triplicates In order to determine the most appropriate point of the parameter, the experiment measured the essential oil volume resulting from the distillation process
3.3.2.1 The cold process for soap production
The cold process of soap making of the study Warra et al (2010) was selected with few minor modifications as this method provides more control over the operation as well as the use of ingredients Furthermore, the process also suits the facility where this study was conducted All the steps are showed in Figure 3.2 below:
Figure 3.3 The cold process of soap making applied in this study
There were 04 factors selected for examination, which are showed with their investigated points as follows:
+ The type of fat/oil suitable for saponification
Table Error! Use the Home tab to apply 0 to the text that you want to appear here The tested types of oil for saponification
+ The proportion of the Tangerine peel essential oil added in the saponification process:
Table Error! Use the Home tab to apply 0 to the text that you want to appear here The tested proportion of Tangerine peel essential oil
+ The amount of additive (turmeric powder) added in the process:
Table Error! Use the Home tab to apply 0 to the text that you want to appear here The amount of turmeric powder added in the saponification process
+ The amount of additive (glycerol) added in the process:
Table Error! Use the Home tab to apply 0 to the text that you want to appear here The amount of glycerol added in the saponification process
The test for sensorial evaluation of this study adapted the technique stipulated in the Vietnamese standard TCVN 1554:1991 on testing techniques for soap bar products However, there were a few modifications with added criteria The original requirements only examine the texture, the color, and the odor while the modified examination in this study also included “skin feel” In this examination, 05 panelists were employed to evaluate the 04 criteria of the output soap The operation for evaluation of each criterion is as follows:
+ Texture (Weight factor 1): Determine externally by observation over the soap bar to check homogeneity, any cracks, or color anomalies + Color (Weight factor 0.8): Cut the soap bar into a half with a sharp knife Observe the cut section to check for color homogeneity + Odor (Weight factor 1): Smell the odor from the cut section of the soap bar
+ Skin feel (Weight factor 1.2): Add water on the soap and apply on the upper-side of the palm and evaluate the foam, the moisturizing effect, and smoothness, and the soothing effect
To score the sensorial properties of the test subjects, this study employed a framework showed in Table 3.10 as follows:
Table Error! Use the Home tab to apply 0 to the text that you want to appear here The sensorial score of different quality levels
The product shows obvious characteristics of the primary ingredient No defects or errors detected
There are few defects that affect insignificantly to the quality of the product’s sensory
There are defects and errors that affect the quality of the product’s sensory but the product still meets the standard
The level of defection and malfunctions lowers the standard of the product Nevertheless, it can still be sold in the market
The level of defection and malfunctions is serious that the makes the product unusable and it cannot be sold Nevertheless, the product is not yet spoiled and can be improved by recycling
Spoiled 0 0 The level of defection and malfunctions is extremely severe The product is considered spoiled and unusable
RESULT AND DISCUSSION
4.1 Optimization of the Tangerine peel essential oil extraction
The material – water ratio involves the cost for input material, particularly water, a precious natural resource This study investigated 03 ratios: 1:3 g/ml, 1:4 g/ml, and 1:5 g/ml and the results of extraction efficiency are showed in Table 4.1 and Figure 4.1 below:
Table Error! Use the Home tab to apply 0 to the text that you want to appear here The amount of essential oils extracted using different material – water ratios Formula Material – water ratio Volume of essential oils extracted
* In the same column, mean values with different lowercase letters indicate significant differences at p < 0.05
Figure 4.1 The essential oils extracted from Tangerine peel with different material – water ratios
The more water was used for submerging the Tangerine peel, the higher amount of essential oils was extracted With the default level of 1:4 g/ml, the extraction yielded 1.40 ml essential oils The yield rose to 1.53 ml when the material – water ratio increased to 1:5 g/ml However, when the ratio was 1:6 g/ml, the extraction did not result in any higher amount of Tangerine peel essential oils Statistically, F3 was equivalent to F2 (1.55 ml vs 1.53 ml) Therefore, the formula F2 with a material – water ratio of 1:5 g/ml was selected as the optimal point for this parameter in the extraction of Tangerine peel essential oils
4.1.2 The NaCl concentration in the water
NaCl is an additional ingredient for the solvent (water), which is capable of enhancing the extraction efficiency while stabilizing the heated extraction process due to its ability to increase the boiling point of the water This study examined 05 points of NaCl concentration in the solvent water and achieved the results demonstrated in Table 4.2 and Figure 4.2 below:
Table Error! Use the Home tab to apply 0 to the text that you want to appear here The amount of essential oils extracted using different NaCl concentrations in water Formula NaCl concentration Volume of essential oils extracted
* In the same column, mean values with different lowercase letters indicate significant differences at p < 0.05
Figure 4.2 The essential oils extracted from Tangerine peel with different NaCl concentrations
The difference between formula F4 and F5 showed a significant impact of salt dissolved in water used for extracting Tangerine peel essential oils Paticularly, with just 1% of salt added to the water (default level), the amount of oils retrieved was 1.54 ml compared to only 1.17 ml of the unsalted water The amount of extracted oils increased to 1.66 ml when 2% NaCl was added in the water However, formula F7 and F8 with 3% and 4% NaCl, respectively, resulted in lower amounts of Tangerine peel essential oils (1.63 ml and 1.51 ml, respectively) This proves the drawbacks of salt added to the essential oil extraction process when it may affect the composition of the volatile compounds through either reaction or structural alteration, which was also recorded in the study of Kammoun Bejar et al (2011) and Karimah & Kristiana (2020) on extracting Orange peel and Mango leaves Therefore, formula F6 with 2% NaCl was selected
This study investigated 03 points of temperature for Tangerine peel essential oil extraction The results on the amount of essential oils are showed in Table 4.3 and Figure 4.3 below:
Table Error! Use the Home tab to apply 0 to the text that you want to appear here The amount of essential oils extracted using different temperatures for extraction Formula Temperature Volume of essential oils extracted
* In the same column, mean values with different lowercase letters indicate significant differences at p < 0.05
Figure 4.3 The essential oils extracted from Tangerine peel with different temperatures
Formula F10 using 120 o C resulted in the highest yield of Tangerine peel essential oils with 1.72 ml Lower or higher temperatures (110 o C and 130 o C) yielded lower amount of essential oils compared to F10 with only 1.65 ml and 1.68 ml, respectively Temperature is a sensitive parameter in extraction as it can accelerate the extraction while also capable of damaging the inner constituents of the inner medium, according to Cvetanović et al (2019) The study of Trần et al (2019) on Vietnamese Tangerine peel also concluded the range of 110 o C – 120 o C was the best temperature for extracting the essential oils of this material
Extraction time is the factor that significantly affects not just the efficiency of the process but also the cost of inputs (electricity and equipment depreciation) With such importance, extraction time is greatly influenced by other operational conditions That is why it was the last factor for optimization The study investigated 05 points of time: 60 minutes, 90 minutes, 120 minutes, 150 minutes and 180 minutes The efficiency of Tangerine essential oil extraction of this experiment is showed in the Table 4.4 and Figure 4.4 below:
Table Error! Use the Home tab to apply 0 to the text that you want to appear here The amount of essential oils extracted using different ranges of time for extraction Formula Extraction time Volume of essential oils extracted
* In the same column, mean values with different lowercase letters indicate significant differences at p < 0.05
Figure 4.4 The essential oils extracted from Tangerine peel with different points of time
The change of essential oil yield was showed clearly on Figure 4.4 with the increasing tendency in the initial 120 minutes, from 1.45 ml of formula F12 (60 minutes) to 1.81 ml of F14 (120 minutes) Furthermore, the rate of escalation was slowed down, meaning the increase between F12 and F13 was greater than that between F13 and F14 To F15 with 150 minutes, however, the yield of Tangerine peel essential oils stopped increasing as the result was statistically identical to that of F14 After 180 minutes (F16), the yield even decreased significantly to 1.68 ml, proving the point of degradation Compared to the study of Trần et al (2019), which concluded 150 minutes, and the study of Ngo et al (2020), which concluded 55 minutes, the result of this experiment has difference Nevertheless, it was due to the difference in operation as the study of Trần et al employed a lower point of temperature when the study of Ngo et al employed microwave assistance
4.2 Determination of the ingredients for soap making based on Tangerine peel essential oils
The study investigated the 02 primary types of oil for soap making, including coconut oil and palm oil In addition, olive oil was also put to the test The sensorial test results are showed in Table 4.5 below:
Table Error! Use the Home tab to apply 0 to the text that you want to appear here Sensorial score of different types of oil for soap making
Texture Color Odor Skin feel
The coconut oil and the palm oil demonstrated superiority compared to the olive oil when the total sensorial test scores of these two (14.12 and 14.64, respectively) were much higher than that of olive oil with just 11.88 Except for the odor, all criteria of the soap produced from olive oil was rated lower However, this is due to the difference in the preference of each market as in the study of Félix et al (2017), olive oil is a preferred ingredients in some Southern Europe countries
Coconut oil and palm oil are the two popular oils for saponification in Vietnam In this study, the palm oil was showed to possess better quality in terms of texture and skin feel as the soap was firm, yet exerted better moisturizing effects The scores of palm oil-based soap’s texture and skin feel were 4.6 and 3.2, respectively, compared to 4.2 and 2.8 of the coconut oil soap On the other hand, the coconut oil-based soap provided better color (brighter) and odor (more fragrant) with scores of 3.2 and 4.0 compared to 3.0 and 3.8 of the palm oil soap, respectively In total, the score of the palm oil soap was higher with 14.64, compared to 14.12 of the coconut oil soap Therefore, palm oil was selected for the production of Tangerine peel essential oil-based soap In reality, the palm oil is favored by some organic-based soap producers in Vietnam such as “sinh dược”
4.2.2 The proportion of Tangerine peel essential oils
As the ingredient that makes up the original characteristics of the product, Tangerine peel essential oils were tested with different proportions in the soap mixture The results are showed in Table 4.6 below:
CONCLUSION
The study had successfully extracted the essential oils out of Tangerine peel with experiments to determine the optimal points of material – water ratio, NaCl concentration, extraction temperature, and extraction time Particularly, to produce a maximum volume of 1.81 ml Tangerine peel essential oils, the hydro- distillation operation requires a material – water ratio of 1:5 g/ml, a NaCl concentration in the water of 2%, an extraction temperature of 105 o C, and an extraction time of 120 minutes
The essential oils were then incorporated in a cold process of soap making to produce soap bars After sensorial tests to determine the suitable ingredients and their amounts, the process was completed with palm oil as the oil for saponification, 2% of Tangerine peel essential oils, 2% of turmeric powder as colorant, and 3% of glycerol This formula gave an excellent quality soap bar with a total sensorial score of 18.80/20 Most of the attributes meet the standards of TCVN 2224:1991 for toilet soap This product shows great promise for commercialization as the raw price is also relatively cheap compared to other organic-based products on the market nowadays
Further tests regarding the anti-oxidation ability and the anti-microbial ability would further solidify the usage of the Tangerine peel essential oils-based soap product in this study
Future studies can compare the sensorial properties of the Tangerine peel essential oils-based soap bars with the soap products based on other types of essential oils such as pomelo, orange, and lemongrass
1 Aiello, A E., Coulborn, R M., Perez, V., & Larson, E L (2008) Effect of hand hygiene on infectious disease risk in the community setting: a meta- analysis American Journal of Public Health, 98(8), 1372–1381
2 Azelee, N I W., Ramli, A N M., Manas, N H A., Salamun, N., Man, R C., & El Enshasy, H (2019) Glycerol in food, cosmetics and pharmaceutical industries: basics and new applications Int J Sci Technol Res, 8, 553–558
3 Boateng, L., Ansong, R., Owusu, W., & Steiner-Asiedu, M (2016) Coconut oil and palm oil’s role in nutrition, health and national development: A review Ghana Medical Journal, 50(3), 189–196
4 Browning, M (2002) Melt and pour soapmaking Sterling Publishing
5 Bustamante, J., van Stempvoort, S., García-Gallarreta, M., Houghton, J A., Briers, H K., Budarin, V L., Matharu, A S., & Clark, J H (2016) Microwave assisted hydro-distillation of essential oils from wet citrus peel waste Journal of Cleaner Production, 137, 598–605
6 Cakaloglu, B., Ozyurt, V H., & Otles, S (2018) Cold press in oil extraction
A review Ukrainian Food Journal, 7, Issue 4, 640–654
7 Chen, M.-H., & Huang, T.-C (2016) Volatile and nonvolatile constituents and antioxidant capacity of oleoresins in three Taiwan citrus varieties as determined by supercritical fluid extraction Molecules, 21(12), 1735
8 Chowdhury, M T., Sarkar, A., Saha, P K., & Anik, R H (2020) Enhancing supply resilience in the COVID-19 pandemic: a case study on beauty and personal care retailers Modern Supply Chain Research and Applications, 2(3), 143–159
9 Coss, M (2016) Handmade Soap Book: Easy Soapmaking with Natural Ingredients Fox Chapel Publishing
10 Cvetanović, A., Švarc-Gajić, J., Zeković, Z., Jerković, J., Zengin, G., Gašić, U., Tešić, Ž., Mašković, P., Soares, C., Fatima Barroso, M., Delerue-Matos, C., & Đurović, S (2019) The influence of the extraction temperature on polyphenolic profiles and bioactivity of chamomile (Matricaria chamomilla L.) subcritical water extracts Food Chemistry, 271, 328–337 https://doi.org/https://doi.org/10.1016/j.foodchem.2018.07.154
11 Denkova-Kostova, R., Teneva, D., Tomova, T., Goranov, B., Denkova, Z., Shopska, V., Slavchev, A., & Hristova-Ivanova, Y (2021) Chemical composition, antioxidant and antimicrobial activity of essential oils from tangerine (Citrus reticulata L.), grapefruit (Citrus paradisi L.), lemon (Citrus lemon L.) and cinnamon (Cinnamomum zeylanicum Blume) Zeitschrift Für
12 Dhakad, A K., Pandey, V V, Beg, S., Rawat, J M., & Singh, A (2018) Biological, medicinal and toxicological significance of Eucalyptus leaf essential oil: a review Journal of the Science of Food and Agriculture, 98(3), 833–848
13 Dover, J S., Moran, M L., Figueroa, J F., Furnas, H., Vyas, J M., Wiviott,
L D., & Karchmer, A W (2020) A path to resume aesthetic care: executive summary of Project AesCert guidance supplement—practical considerations for aesthetic medicine professionals supporting clinic preparedness in response to the SARS-CoV-2 outbreak Facial Plastic Surgery & Aesthetic Medicine, 22(3), 125–151
14 Dugo, P., Mondello, L., Favoino, O., Cicero, L., Zenteno, N A R., & Dugo,
G (2005) Characterization of cold-pressed Mexican dancy tangerine oils
Flavour and Fragrance Journal, 20(1), 60–66 https://doi.org/https://doi.org/10.1002/ffj.1367
15 Dyett, J., & Thomas, C (2019) Overpopulation discourse: Patriarchy, racism, and the specter of ecofascism Perspectives on Global Development and Technology, 18(1–2), 205–224
16 Eroglu, M., Mutluoglu, M., Uzun, G., & Ay, H (2012) Caustic skin burn caused by sodium hydroxide BMJ Case Reports, 2012 https://doi.org/10.1136/bcr-2012-007103
17 Félix, S., Araújo, J., Pires, A M., & Sousa, A C (2017) Soap production: A green prospective Waste Management, 66, 190–195
18 Furtado, H C., & May, I Le (2004) High temperature degradation in power plants and refineries Materials Research, 7(1), 103–110 https://doi.org/10.1590/s1516-14392004000100015
19 Gbaj, M A., Sadawe, I A., Meiqal, N M., Bensaber, S M., Maamar, M S., Hermann, A., & Gbaj, A M (2019) Evaluation of neuropharmacological activities of methanolic and aqueous extracts of Citrus reticulata (Rutaceae) fruit peels Am J Biomed Sci Res, 2(4), 131–135
20 Giuliano, C A., & Rybak, M J (2015) Efficacy of triclosan as an antimicrobial hand soap and its potential impact on antimicrobial resistance: a focused review Pharmacotherapy: The Journal of Human Pharmacology and Drug Therapy, 35(3), 328–336
21 Golmakani, M.-T., & Rezaei, K (2008) Comparison of microwave-assisted hydrodistillation withthe traditional hydrodistillation method in the extractionof essential oils from Thymus vulgaris L Food Chemistry, 109(4), 925–930
22 Greguš, J., & Guillebaud, J (2020) Doctors and overpopulation 48 years later: a second notice The European Journal of Contraception & Reproductive Health Care, 25(6), 409–416
23 Jaul, E., & Barron, J (2017) Age-related diseases and clinical and public health implications for the 85 years old and over population Frontiers in Public Health, 5, 335
24 Johnson, O O., Ayoola, G A., & Adenipekun, T (2013) Antimicrobial activity and the chemical composition of the volatile oil blend from Allium sativum (Garlic Clove) and Citrus reticulata (Tangerine Fruit) International
Journal of Pharmaceutical Sciences and Drug Research, 5(4), 187–193
25 Kammoun Bejar, A., Ghanem, N., Mihoubi, D., Kechaou, N., & Boudhrioua Mihoubi, N (2011) Effect of infrared drying on drying kinetics, color, total phenols and water and oil holding capacities of orange (Citrus sinensis) peel and leaves International Journal of Food Engineering, 7(5)
26 Karimah, Z N., & Kristiana, R (2020) Quality testing of solid soap with mango leaf extract (Mangifera indica L.) produced by hot and cold processes Proceeding International Conference on Science and Engineering, 3, 171–173
27 Kirbaşlar, F G., Tavman, A., Dülger, B., & Türker, G (2009) Antimicrobial activity of Turkish citrus peel oils Pak J Bot, 41(6), 3207–3212
28 Knowles, J., Ettenson, R., Lynch, P., & Dollens, J (2020) Growth opportunities for brands during the COVID-19 crisis MIT Sloan Management Review, 61(4), 2–6
29 Kwangjai, J., Cheaha, D., Manor, R., Sa-Ih, N., Samerphob, N., Issuriya, A., Wattanapiromsakul, C., & Kumarnsit, E (2021) Modification of brain waves and sleep parameters by Citrus reticulata Blanco cv Sai-Nam-Phueng essential oil Biomedical Journal, 44(6), 727–738
30 Letcavage, E (2009) Basic soap making: All the skills and tools you need to get started Stackpole Books
31 Maotsela, T., Danha, G., & Muzenda, E (2019) Utilization of Waste Cooking Oil and Tallow for Production of Toilet “Bath” Soap Procedia Manufacturing, 35, 541–545
32 McGhee, J., Lilja, A., Strong, C., Bailey, B., & Thordarson, P (2019) Soap versus COVID-19 In SIGGRAPH Asia 2020 Computer Animation Festival
33 Milani, M., & Sparavigna, A (2017) The 24-hour skin hydration and barrier function effects of a hyaluronic 1%, glycerin 5%, and Centella asiatica stem cells extract moisturizing fluid: an intra-subject, randomized, assessor- blinded study Clinical, Cosmetic and Investigational Dermatology, 311–
34 Mirghafourvand, M., Charandabi, S M.-A., Hakimi, S., Khodaie, L., & Galeshi, M (2016) Effect of orange peel essential oil on postpartum sleep quality: A randomized controlled clinical trial European Journal of Integrative Medicine, 8(1), 62–66
35 Ngo, T C Q., Tran, T K N., Nguyen, V M., & Mai, H C (2020) Optimization of green mandarin (Citrus reticulata) essential oil extraction using microwave-assisted hydrodistillation and chemical composition analysis IOP Conference Series: Materials Science and Engineering, 991(1) https://doi.org/10.1088/1757-899X/991/1/012122
36 Ott, A (2021) The Art of Manufacturing Soap and Candles: Incluiding the most recent Discoveries, embracing all Kinds of ordinary Hard, Soft, and Toilet Soaps, especially those made by the cold Process BoD–Books on
37 Pierce, A (2013) Soap Making Recipes: Soap Making For Beginners
38 Rajput, S., Kaur, S., Panesar, P S., & Thakur, A (2022) Supercritical fluid extraction of essential oils from Citrus reticulata peels: optimization and characterization studies Biomass Conversion and Biorefinery https://doi.org/10.1007/s13399-022-02807-4
39 Rashed, M M A., You, L., Ghaleb, A D S., & Du, Y (2023) Two-Phase Extraction Processes, Physicochemical Characteristics, and Autoxidation Inhibition of the Essential Oil Nanoemulsion of Citrus reticulata Blanco (Tangerine) Leaves In Foods (Vol 12, Issue 1) https://doi.org/10.3390/foods12010057
40 Rios, J.-L (2016) Essential oils: What they are and how the terms are used and defined In Essential oils in food preservation, flavor and safety (pp 3– 10) Elsevier
41 Rosa, A., Era, B., Masala, C., Nieddu, M., Scano, P., Fais, A., Porcedda, S.,
& Piras, A (2019) Supercritical CO2 extraction of waste citrus seeds: Chemical composition, nutritional and biological properties of edible fixed oils European Journal of Lipid Science and Technology, 121(7), 1800502
42 Saxton, K., Crosby, B., & Dunn, K (2013) Formulation of transparent melt and pour soaps without petroleum derivatives Journal of Sciences, 2
43 Singh, B., Singh, J P., Kaur, A., & Singh, N (2020) Phenolic composition, antioxidant potential and health benefits of citrus peel Food Research International, 132, 109114
44 Soe’eib, S., Asri, N P., & NH, A S D S (2017) Enfleurage essential oil from jasmine and rose using cold fat adsorbent Widya Teknik, 15(1), 58–61
45 Sousa, L L., Lucena, I L., & Fernandes, F A N (2010) Transesterification of castor oil: Effect of the acid value and neutralization of the oil with glycerol Fuel Processing Technology, 91(2), 194–196
46 Trần, H., Ngô, Q., Linh, H., Le, T., Quan, P., & Quoc Toan, T (2019) Essential Oil from Vietnamese Mandarin (Citrus reticulata Blanco) Using Hydrodistillation Extraction Process and Identification of it’s Components
Solid State Phenomena, 298, 100–105 https://doi.org/10.4028/www.scientific.net/SSP.298.100
47 Tukey Jr, H B (1970) The leaching of substances from plants Annual Review of Plant Physiology, 21(1), 305–324
48 Warra, A A., Hassan, L G., Gunu, S Y., & Jega, S A (2010) Cold-process synthesis and properties of soaps prepared from different triacylglycerol sources Nigerian Journal of Basic and Applied Sciences, 18(2)
49 Xiong, K., & Chen, Y (2020) Supercritical carbon dioxide extraction of essential oil from tangerine peel: Experimental optimization and kinetics modelling Chemical Engineering Research and Design, 164, 412–423 https://doi.org/https://doi.org/10.1016/j.cherd.2020.09.032
50 Yu, E A., Kim, G.-S., Jeong, S W., Park, S., Lee, S J., Kim, J H., Lee, W S., Bark, K.-M., Jin, J S., & Shin, S C (2014) Flavonoid profile and biological activity of Korean citrus varieties (II): Pyunkyul (Citrus tangerina Hort ex Tanaka) and overall contribution of its flavonoids to antioxidant effect Journal of Functional Foods, 6, 637–642
51 Zhao, F., Yan, Z., Sun, J., Ma, Z., Kang, X., Ji, Z., Yang, X., Wan, P., & Zhou, H (2022) Essential oils from citri reticulatae pericarpium: Optimization of hydrodistillation extraction and effects of stir-frying processing on chemical components and multiple biological activities
Industrial Crops and Products, 189, 115825 https://doi.org/https://doi.org/10.1016/j.indcrop.2022.115825
Data analysis results + Material – water ratio
Test of Homogeneity of Variances
Levene Statistic df1 df2 Sig
Sum of Squares df Mean Square F Sig
95% Confidence Interval Lower Bound Upper Bound L
* The mean difference is significant at the 0.05 level
Means for groups in homogeneous subsets are displayed a Uses Harmonic Mean Sample Size = 3.000
Test of Homogeneity of Variances
Levene Statistic df1 df2 Sig
Sum of Squares df Mean Square F Sig
Means for groups in homogeneous subsets are displayed
Means for groups in homogeneous subsets are displayed a Uses Harmonic Mean Sample Size = 3.000
Test of Homogeneity of Variances
Levene Statistic df1 df2 Sig
Sum of Squares df Mean Square F Sig
95% Confidence Interval Lower Bound Upper Bound L
* The mean difference is significant at the 0.05 level
Means for groups in homogeneous subsets are displayed a Uses Harmonic Mean Sample Size = 3.000
Test of Homogeneity of Variances
Levene Statistic df1 df2 Sig
Sum of Squares df Mean Square F Sig
Means for groups in homogeneous subsets are displayed a Uses Harmonic Mean Sample Size = 3.000