Description:FIELD OF THE INVENTION
The present invention relates to the field of natural product extraction and essential oil recovery. More specifically, it pertains to the comparative evaluation of two extraction techniques—Soxhlet extraction and hydro distillation—for determining the efficiency, yield, and quality of essential oil obtained from kinnow (Citrus reticulata) peel. This invention is relevant to the domains of food technology, pharmaceutical sciences, perfumery, and nutraceutical industries, where natural citrus-based essential oils are used for their aromatic, antimicrobial, and therapeutic properties.
BACKGROUND OF THE INVENTION
References which are cited in the present disclosure are not necessarily prior art and therefore their citation does not constitute an admission that such references are prior art in any jurisdiction. All publications, patents and patent applications herein are incorporated by reference to the same extent as if each individual or patent application was specifically and individually indicated to be incorporated by reference.
The extraction of essential oils from citrus peels such as Kinnow presents several challenges. These include the breakdown of thermolabile chemicals brought on by extended heating, insufficient extraction that results in a decreased yield, excessive energy use, and drawn-out processing periods. Hydro distillation and Soxhlet extraction have been employed historically, however there is still work to be done to optimize these techniques for increased output and efficiency.
Environmental sustainability is also impacted by other problems including water utilization in hydro distillation and solvent recovery in Soxhlet. The purpose of this study is to determine which approach produces essential oil with the highest yield and quality while also being more economical and environmentally beneficial.
While various studies have evaluated essential oil extraction methods, limited research has directly compared Soxhlet extraction with hydro distillation specifically for Kinnow peel. Most existing research focuses on common citrus fruits like oranges or lemons, neglecting Kinnow. Moreover, the existing studies often overlook comprehensive analysis of yield efficiency, oil quality, and environmental impact. This study fills that gap by evaluating and comparing both techniques using-controlled parameters to determine the most effective and sustainable method for essential oil extraction from Kinnow peel.
One of the principal fruit crops grown in nations with tropical or subtropical climates is citrus fruit. With 599 lakh tonnes produced year, India is the world's largest producer of citrus fruits. Citrus fruits are mostly processed to make juice in addition to being consumed in great quantities as fresh fruits. Peels, seeds, and pulps from citrus processing—which make up almost half of the raw, processed fruit—can yield valuable byproducts. Due to their application in the food business, cosmetics, and traditional medicine, citrus industry by-products are highly significant both economically and medicinally.The citrus fruit variety known as kinnow or tangerine (Citrus reticulata) is well-liked due to its high juice content, sweet flavor, and oblate, neckless shape.
The albedo and the flavedo are two distinct tissues present in Kinnow peel. The outer layer of the flavedo peel contains essential oils that are used in the flavor and fragrance industries. Nutrients like proteins, carbohydrates, minerals, and fiber are abundant in albedo. Essential oils extracted from citrus peels have been studied for their inherent antioxidant and antibacterial qualities and are said to be one of the abundant sources of bioactive substances, including coumarins, flavonoids, carotenes, terpenes, and linalool.
Soxhlet extraction and hydro distillation are two popular laboratory-scale methods that are the subject of this investigation. Soxhlet extraction is effective for exhaustive extraction since it entails continuously washing the sample with a volatile solvent while refluxing. However, thermolabile chemicals can be degraded by continuous heating.
In contrast, hydro distillation entails boiling plant material in water and collecting the steam that contains vapors of essential oils. After that, the vapors are separated and condensed. This approach is more conventional, easier, and generally better for protecting substances that are susceptible to heat. This study compares the effectiveness of these two approaches in terms of removing essential oil from Kinnow peel.
Several patents issued for oil extraction but none of these are related to the present invention. Patent CN102586023B discloses a method for extracting citrus peel essential oil. The method selects fresh citrus peels, removes the white cortex until the thickness of the peels is 0.1-0.2 cm, chops them up, freezes and thaws them repeatedly for 2-5 times, and then according to the mass ratio of pectinase and cellulase of 1:1-6:1 Prepare compound enzyme and enzyme solution, mix the pretreated citrus peel particles with the compound enzyme solution, and enzymatically hydrolyze for 5-30 minutes in the dark; use n-hexane to condense and reflux the enzymolyzed citrus peel to remove n-hexane Alkanes, that is, essential oils. This method first uses the physical method of repeated freezing and thawing to initially destroy the cell wall of citrus peel, and then combines the compound enzyme to enzymolyze the citrus peel, which greatly improves the extraction rate of citrus peel essential oil, the extraction process is simple, and the natural aroma is less damaged. It can maximize the use value of the by-product of citrus processing - citrus peel. The essential oil extracted by this method is pure in texture and has a natural citrus fruity aroma.
Another patent US10569193B2 directed to a modular distillation system incorporating a removable capsule for containing source material for extraction. Through the action of the invention, the steam distillation process described herein produces a substantially larger amount of volatile oil than a distillation system that does not use an enclosed, modular system. The present invention provides for an apparatus that allows for greater contact between the steam and plant matter during the distillation process through the use of a closed removable capsule containing relatively small amount of plant matter. Additionally, the present invention is directed to a system that allows the generation of higher quality distillate and considerably higher quantity of volatile oil extracts by forcing the steam to evenly disperse through a removable capsule, and by preventing the condensed liquid to return back to the boiling water within the vessel.
Another patent JP2006291007A provides a method for effective extraction of a safe essential oil from a fruit skin of a citrus and for utilizing the fruit skin of the citrus that has been handled as an industrial waste as an effective resource. A closed casing 6 is equipped with an input port 8 for a residue remained after squeezing a fruit juice from the citrus, and a first suction port 15. A temperature in the casing 6 is elevated by a heating means to evaporate water and the essential oil from the residue. A condenser 85 cools and condenses water and the essential oil that are sucked from the first suction port 15 and evaporated in order to exhaust a condensate. A closed reservoir 90 stores the condensate from the condenser 85 and is equipped with a second suction port 94. A vacuum pump 96 (a vacuum means) sucks air through the second suction port 94 to evacuate the casing 6. A electric motor 33 (a rotation means) rotates a driving shaft that is closely inserted to a shaft inserting hole set in the casing 6. The driving shaft is equipped with a stirring blade to agitate and grind the residue.
Another patent CN109072127A relates to the methods that essential oil and/or derived essential oil are obtained from the pericarp of citrus fruit and/or in the herbaceous plant with high residue moisture content, it is the following steps are included: a) extract wet extraction material with comprising the extractant mixture of at least one polar solvent and at least one nonpolar solvent, mix oil to obtain, wherein residue and/or the herbaceous plant extracted material and be selected from citrus fruit peels and/or the juice production from citrus fruit, wherein the residual moisture content for extracting material is calculated as 5 to 95 quality % with the gross mass for extracting material, wherein the extractant mixture contains at least one nonpolar solvent, the ratio of the nonpolar solvent is with the total volume meter of the extractant mixture for 45 to 95 volume %, wherein the temperature of the extractant mixture is higher than environment temperature but is lower than The minimum boiling point solvent of the extractant mixture or the boiling point of minimum boiling point azeotropic mixture;B) oil that mixes is separated with the extraction material;C) by it is described mix oil or the extractant mixture and distilled with the essential oil and/or the derived essential oil separate.
Another patent CN105886123A provides an extraction technique of lavender essential oil. The technique comprises the following steps: picking and cleaning, naturally drying in the shade, activating and pulverizing; adding a sodium chloride solution, and immersing; carrying out atmospheric distillation, and boiling the extracting solution; obtaining a condensate; carrying out oil-water separation; adding an ethanol solution into an activated carbon adsorption column to extract oil in the activated carbon adsorption column, thereby obtaining crude oil; and extracting, stratifying, and separating out the supernatant, thereby obtaining the lavender essential oil. The organic solvent for extraction is the ethanol solution which can be thoroughly volatilized in the extraction process, so the product does not have ethanol residues and does not have any toxic or harmful effect on the human body. The lavender essential oil can be used for preparing cosmetics, washing supplies, medicines and the like, and thus, has wide application range.
OBJECTS OF THE INVENTION
Main object of the present invention is to extract essential oil from kinnow (Citrus reticulata) peel using Soxhlet extraction and hydro distillation techniques.
Another object of the present invention is to evaluate and compare the yield of essential oil obtained from both extraction methods.
Another object of the present invention is to analyze the physicochemical properties and quality parameters of the essential oils extracted by each technique.
Another object of the present invention is to identify the more efficient and eco-friendly method for essential oil recovery from citrus peel waste.
Another object of the present invention is to promote the value addition and utilization of agro-industrial waste (kinnow peel) for sustainable essential oil production.
SUMMARY OF THE INVENTION
This summary is provided to introduce a selection of concepts, in a simplified format, that are further described in the detailed description of the invention.
This summary is neither intended to identify key or essential inventive concepts of the invention and nor is it intended for determining the scope of the invention.
To further clarify advantages and features of the present invention, a more particular description of the invention will be rendered by reference to specific embodiments thereof, which is illustrated in the appended drawings.
The present invention relates to a comparative study for the extraction of essential oil from kinnow (Citrus reticulata) peel using two distinct techniques—hydro-distillation and Soxhlet extraction. The method involves collection, cleaning, and drying of fresh kinnow peels, followed by grinding into coarse particles to increase surface area and enhance extraction efficiency.
In the hydro-distillation method, a combination of fresh peel and dried peel powder was mixed with water and heated at 70°C for 3–4 hours until oil extraction ceased. In contrast, the Soxhlet extraction involved placing 50 g of crushed peel into a cellulose thimble, using 200 ml of acetone as the solvent at 65°C, and operating under continuous reflux for 6 hours. The resulting extract was concentrated using a rotary evaporator to obtain the essential oil.
The invention aims to compare the yield and efficiency of both methods, thereby identifying the more suitable technique for the sustainable recovery of essential oil from kinnow peel, a valuable agro-industrial waste.
Herein enclosed a method for extracting essential oil from kinnow (Citrus reticulata) peel, comprising the steps of
collecting fresh kinnow peels;
cleaning the peels, drying them in a hot air oven to remove moisture;
crushing the dried peels into coarse particles; and
subjecting the ground peel to extraction by hydro-distillation or Soxhlet extraction.
The hydro-distillation is carried out by mixing 200 g of fresh kinnow peel with 500 ml of water and 50 g of mechanically and solarly dried peel powder with 200 ml of water in a round-bottomed flask, and heating the mixture at 70°C for 3 to 4 hours until oil extraction is complete.
The Soxhlet extraction is carried out by placing 50 g of crushed kinnow peel into a cellulose thimble, using 200 ml of acetone as the solvent, maintaining the extraction at 65°C under continuous reflux for 6 hours, and recovering the essential oil by concentrating the extract in a rotary evaporator.
The crushing of dried kinnow peel is performed to increase surface area and improve extraction efficiency during both hydro-distillation and Soxhlet extraction processes.
The essential oil yield obtained from hydro-distillation and Soxhlet extraction is measured and compared to determine the more effective and efficient method for essential oil recovery from kinnow peel.
BRIEF DESCRIPTION OF THE DRAWINGS
The illustrated embodiments of the subject matter will be understood by reference to the drawings, wherein like parts are designated by like numerals throughout. The following description is intended only by way of example, and simply illustrates certain selected embodiments of devices, systems, and methods that are consistent with the subject matter as claimed herein, wherein:
Fig 1: making steps
Fig 2: hydro distillation assembly
Fig 3: Soxhlet Assembly
Fig 4: Appearance
Fig 5: FFA test
Fig 6: TPC method
Fig 7: TFC method
Fig 8: Iodine method
Fig 9: Peroxide test
Fig 10: Appearance of products
Fig 11: Standard graph for TPC
Fig 12: Standard graph for TFC
DETAILED DESCRIPTION OF THE INVENTION
The detailed description of various exemplary embodiments of the disclosure is described herein with reference to the accompanying drawings. It should be noted that the embodiments are described herein in such details as to clearly communicate the disclosure. However, the amount of details provided herein is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the scope of the present disclosure as defined by the appended claims.
It is also to be understood that various arrangements may be devised that, although not explicitly described or shown herein, embody the principles of the present disclosure. Moreover, all statements herein reciting principles, aspects, and embodiments of the present disclosure, as well as specific examples, are intended to encompass equivalents thereof.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments. As used herein, the singular forms “a",” “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises,” “comprising,” “includes” and/or “including,” when used herein, specify the presence of stated features, integers, steps, operations, elements and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and/or groups thereof.
It should also be noted that in some alternative implementations, the functions/acts noted may occur out of the order noted in the figures. For example, two figures shown in succession may, in fact, be executed concurrently or may sometimes be executed in the reverse order, depending upon the functionality/acts involved.
In addition, the descriptions of "first", "second", “third”, and the like in the present invention are used for the purpose of description only, and are not to be construed as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Thus, features defining "first" and "second" may include at least one of the features, either explicitly or implicitly.
Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which example embodiments belong. It will be further understood that terms, e.g., those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
In some embodiments of the present invention, a comparative study for the extraction of essential oil from kinnow (Citrus reticulata) peel using two distinct techniques—hydro-distillation and Soxhlet extraction.
In some embodiments of the present invention, the method involves collection, cleaning, and drying of fresh kinnow peels, followed by grinding into coarse particles to increase surface area and enhance extraction efficiency.
In some embodiments of the present invention, in the hydro-distillation method, a combination of fresh peel and dried peel powder was mixed with water and heated at 70°C for 3–4 hours until oil extraction ceased.
In some embodiments of the present invention, in contrast, the Soxhlet extraction involved placing 50 g of crushed peel into a cellulose thimble, using 200 ml of acetone as the solvent at 65°C, and operating under continuous reflux for 6 hours. The resulting extract was concentrated using a rotary evaporator to obtain the essential oil.
Herein enclosed a method for extracting essential oil from kinnow (Citrus reticulata) peel, comprising the steps of
collecting fresh kinnow peels;
cleaning the peels, drying them in a hot air oven to remove moisture;
crushing the dried peels into coarse particles; and
subjecting the ground peel to extraction by hydro-distillation or Soxhlet extraction.
The hydro-distillation is carried out by mixing 200 g of fresh kinnow peel with 500 ml of water and 50 g of mechanically and solarly dried peel powder with 200 ml of water in a round-bottomed flask, and heating the mixture at 70°C for 3 to 4 hours until oil extraction is complete.
The Soxhlet extraction is carried out by placing 50 g of crushed kinnow peel into a cellulose thimble, using 200 ml of acetone as the solvent, maintaining the extraction at 65°C under continuous reflux for 6 hours, and recovering the essential oil by concentrating the extract in a rotary evaporator.
The crushing of dried kinnow peel is performed to increase surface area and improve extraction efficiency during both hydro-distillation and Soxhlet extraction processes.
The essential oil yield obtained from hydro-distillation and Soxhlet extraction is measured and compared to determine the more effective and efficient method for essential oil recovery from kinnow peel.
EXAMPLE 1
BEST METHOD
Methodology
Fresh Kinnow peels were gathered, cleaned, and allowed to dry in hot air oven for moisture elimination. To improve extraction efficiency, the dried peels were crushed into coarse particles to enhance surface area. Then those ground peel is used for extraction of essential oil by two different methods.
Hydro-distillation
In order to extract oil from the oil-water emulsion that was produced physically, from fresh Kinnow peel, and from mechanically and solarly dried Kinnnow peel powder, a mixture of 200 g of fresh Kinnow peel, 500 ml of water, 50 g of mechanically and solarly dried peel powder, and 200 ml of water was placed in a round-bottomed flask and heated to 70°C for 3-4 hours, or until no more oil could be extracted.
Soxhlet Extraction
50g of crushed peel was put into a cellulose thimble. The solvent used was acetone of 200ml at 65?. A condenser, Soxhlet extractor, and round-bottom flask were all part of the equipment. The extraction process was carried out for 6 hours under continuous reflux. To extract the oil, the extract was concentrated in a rotary evaporator.
EXAMPLE 2
Testing:
Oil Yield was measured by weight and expressed as a percentage of the original sample.
The percent yield of oil recovered was determined by employing the use of the following equation.
Oil yield (%) = Woe X 100 / Ws
Where, Woe = weight of oil extracted, Ws = weight of sample before extraction
Appearance Oil extracted by Soxhlet method exhibited a darker color and stronger aroma. Whereas oil extracted by hydro-distillation method has lighter in color and having strong aroma.
FFA = A 250-ml stopper flask was precisely weighed with 2 grams of the oil sample from solvent extraction and 0.25 grams from hydrodistillation. 50 millilitres of ethanol were brought to a boil in a second flask, and it was neutralized using 0.1 M potassium hydroxide and phenolphthalein indicator when it was still above 70 °C. The first flask containing the oil was filled with the neutralized ethanol, and the contents were combined. After boiling them, they were titrated with 0.1 M potassium hydroxide while still hot, shaking briskly. When a single drop of 0.1 M potassium hydroxide was added, the titration achieved its end point when there was a slight but noticeable color shift that lasted for at least 15 seconds.
The FFA was then calculated by:
FFA= 28.2 x V x N \ Wo
Where, FFA= free fatty acid (mg KOH/g), V= volume of 0.1 M potassium hydroxide used (ml), N= normality of the ethanolic potassium hydroxide (0.1 M), and Wo=weight of oil (g).
TPC = We used the Folin-Ciocalteu method to evaluate the total phenolic content of kinnow byproduct extracts that were produced using various extraction procedures. To the test tubes with 2.5 mL of 7.5% sodium carbonate, 0.5 mL of solvent extract, and Folin-Ciocalteu
After adding the reagent (2.5 mL; 10-fold), the mixture was incubated for 30 minutes at 25°C. For the standard curve, a similar process was used, adding 0.5 mL of a gallic acid solution in linear fashion to separate test tubes in place of the extract. The gallic acid equivalents per gram of extract (mg GAE/g sample) were used to express the overall phenolic content. After 30 minutes, the absorbance was measured with a UV-Vis spectrophotometer at 765 nm.
TFC = Using quercetin as a standard, the aluminum chloride technique was used to calculate the total flavonoid concentration. In a volumetric flask, 0.5 mL of Kinnow by-product extract and 4 mL of water were added. Aluminum chloride (10%; 0.3 mL) and sodium nitrite (5%; 0.3 mL) were added after 5 minutes. The reaction mixture was incubated for six minutes at room temperature with the addition of sodium hydroxide (2 mL, 1M). Distilled water was used to make up the remaining volume to 10 mL, and absorbance was measured at 510 nm. The formula based on the calibration curve was used to determine the total flavonoid content in quercetin equivalents (mg QE/100 g).
Iodine Value = A total of 25 millilitres of carbon tetrachloride were used to dissolve one gram of the oil. After adding 25 millilitres of Wijs solution, the reaction was run for one hour in the dark. The addition of potassium iodide solution halted the process. A solution of sodium thiosulfate (0.1 M) was used to titrate the residual iodine.
Iodine value = 12.69 (B-S) X N(0.1)Na2S2O3 \ Ws
Where Ws= sample weight, B= Blank, S=Sample reading.
Carotenoids Content = To determine the carotenoid content in essential oil extracted from kinnow peel, a 0.1 mL sample of the essential oil is mixed with 7 mL of n-hexane and 3 mL of acetone in a clean test tube. To guarantee that the solvents and oil are completely mixed, the mixture is thoroughly homogenized using a vortex shaker. The solution is then centrifuged for 10 minutes at 3000 rpm in order to separate the phases. To get rid of any leftover particles, the supernatant is meticulously filtered after centrifugation. The absorbance of the clear filtrate is then measured at 450 nm, which is the wavelength at which carotenoids have the highest absorbance, in order to perform spectrophotometric analysis.
Carotenoid Content = Conc. x final Volume (ml) x 100 \ Ws (g)
Where, Conc. is concentration of sample, Ws = Weight of Sample
Refractive Index = An Abbe refractometer was used to measure the essential oil's refractive index (RI) after it was extracted from kinnow peel. To ensure complete coverage free of air bubbles, a few drops of the oil sample were applied to the refractometer's prism surface. To guarantee accuracy, the device was calibrated with pure water prior to measurement. At room temperature, usually about 25°C, the refractive index was measured by turning a knob until the viewfinder showed a distinct border between the light and dark areas.
Peroxide Value = One gram of the oil sample and thirty milliliters of acetic acid chloroform solution were measured and added to a flask. After that, 30 ml of distilled water was added, immediately followed by 0.5 ml of a saturated potassium iodide solution. After the yellow hue nearly vanished, the flask content was titrated against 0.01 M sodium thiosulfate. After adding 0.5 ml of starch indicator, the titration was carried out until the end point, where the blue-black color simply vanished. Equally, a blank titration was carried out.
Peroxide Value = (S-B) X N of Na2S2O3 X 1000 \ Ws
Where, S = Sample, B = Blank, Ws = Sample weight
DPPH = 1 ml of 0.1 mM DPPH methanolic solution was combined with an aliquot of 1 ml of 10% essential oil. For half an hour, the mixture was incubated at room temperature (about 22 °C) in the dark. The absorbances of a sample at 517 nm were then measured in a spectrophotometer. The same process was also used to determine the absorbance of a free-oil methanolic solution (A control).
DPPH scavenging activity was determined using equation:
(%inhibition) = (Abs. of Control – Absorbance of Sample) x 100 \ Absorbance of Control
Results:
Oil Yield = Oil yield (%) = Woe X 100 / Ws
Soxhlet Extraction = 0.68g X 100 \ 20g = 3.4%
Hydro – Distillation = 0.8g X 100 \ 36.27g = 2.2%

Appearance: Appearance of A. Soxhlet oil exhibited a darker color and stronger aroma as compare to B. hydrodistillation oil which is shown below.
FFA = Free fatty acid (mg KOH/g), = 28.2 x V x N \ Wo
Soxhlet Extraction = 28.2 x 1.6 x 0.1 \ 2.06 = 2.19mg KOH\g
Hydro – Distillation = 28.2 x 0.2 x 0.1 \ 0.25 = 2.25mg KOH\g
The Colour changes during titration shows the volume reading ( red to light pink ).
TPC - The total phenolic content (TPC) of essential oil extracted from kinnow peel, measured at 765 nm using gallic acid as the standard for the calibration curve, was found to be 43.36 mg/100 g for Soxhlet extraction and 93.84 mg/100 g for hydrodistillation.
TFC – Using quercetin as the standard and measuring absorbance at 510 nm, the total flavonoid content (TFC) of kinnow peel essential oil was determined to be 9.821 mg quercetin per 100 g when extracted via Soxhlet, and 18.078 mg quercetin per 100 g using hydrodistillation.
Iodine Value = 12.69 (B-S) X N(0.1)Na2S2O3 \ Ws.
Soxhlet Extraction= 12.69 (32.5-17.5) x 0.1\ 0.2g = 95.17mgI2\100mg
Hydro – Distillation = 12.69 (32.5 – 14.5) x 0.1\ 0.26g = 87.85mgI2\100mg
The colour turns to colourless shows the iodine indication.
Carotenoids Content (ug of carotene \100g) = Conc. x final Volume (ml) x 100 \ Ws (g)
Soxhlet Extraction = 0.303 x 10.5x 100 \ 0.4 = 795.37ug \100g
Hydro – Distillation =0.009 x 10.1 x 100 \ 0.08 =113.62ug \ 100g
Refractive Index = At room temperature, usually about 25°C, the refractive index was measured.
Soxhlet Extraction = 1.45
Hydro – Distillation =1.39
Peroxide Value = (S-B) X N of Na2S2O3 X 1000 \ Ws.
Soxhlet Extraction= (2.9-0.4) x 0.01x1000\ 3.9g = 3.41meq\100kg
Hydro – Distillation= (3.9-0.4) x 0.01 x 1000\2.05g = 17.07mq\100kg.
The colourless change from blue black colour indicates peroxide value.
DPPH = Essential oils are a rich source of antioxidants (%inhibition) = (Abs. of Control – Absorbance of Sample) x 100 \ Absorbance of Control.
Soxhlet Extraction = (1.78-0.120) x 100 \ 1.78 = 93.25%
Hydro – Distillation = (1.78-0.24) x 100 \ 1.78 = 86.51%
Parameters Hydro distillation Soxhlet Extraction
1. Oil Yield Lower (2.1%) Higher ( 3.4%)
2. Time Consumption Shorter (3hr) Longer (6hr)
3. Temperature Stability More Stable Less Stable (Continously heat)
4. Energy Efficiency Higher Lower
5. Solvent use No Yes ( e.g Acetone)

Discussion: The Soxhlet extraction method yielded a higher quantity of essential oil, likely due to the solvent's deep penetration and the continuous reflux, which enhances compound extraction through repeated washing of the sample matrix. However, hydro-distillation better preserved the natural aroma of the oil and offered a more environmentally sustainable approach, as it does not require the use of organic solvents.
Visual differences between the two oils were clearly evident. The essential oil obtained through hydrodistillation appeared lighter and more transparent, while the Soxhlet-extracted oil exhibited a darker hue—possibly a result of thermal degradation or the co-extraction of pigments caused by solvent use.
In terms of total phenolic content (TPC), hydrodistillation demonstrated significantly higher values (93.84 mg/100 g) compared to Soxhlet extraction (43.36 mg/100 g), indicating that the steam-based method is more effective at preserving or extracting phenolic compounds—key contributors to antioxidant activity.
Correspondingly, the antioxidant activity, as measured by assays such as DPPH or ABTS, was greater in the hydrodistilled oil. This enhanced activity can be attributed to the higher concentration of phenolics and flavonoids, both of which are known for their antioxidant properties.
Total flavonoid content (TFC) followed a similar trend, with hydrodistillation yielding 18.078 mg quercetin/100 g compared to 9.821 mg quercetin/100 g in the Soxhlet extract. The superior performance of hydrodistillation in retaining flavonoids may be due to reduced solvent interaction and shorter exposure to heat, which helps minimize degradation.
In conclusion, hydrodistillation emerged as the more suitable technique for extracting high-quality essential oil from kinnow peel. It not only ensured a better yield of bioactive compounds but also preserved sensory attributes such as color and aroma. While Soxhlet extraction is effective for exhaustive compound recovery, its reliance on solvents and prolonged heating may compromise the chemical integrity and sensory quality of the oil.
ADVANTAGES OF THE INVENTION:
1. Rich in natural limonene, a substance that is used in the cleaning and fragrance industries.
2. Has strong antifungal and antibacterial qualities.
3. Provides antioxidant activity that is good for preserving food.
4. Serves as an organic bug deterrent.
5. Fit for use in skincare and natural cosmetics.
6. Non-toxic and biodegradable.
7. Offers value addition as a means of cutting down on citrus waste.
8. Suitable for use as a flavoring agent in drinks and candies.
9. Economically advantageous for growers of citrus.
10. Encourages green and sustainable chemistry methods.

, Claims:1. A method for extracting essential oil from kinnow (Citrus reticulata) peel, comprising the steps of
collecting fresh kinnow peels;
cleaning the peels, drying them in a hot air oven to remove moisture;
crushing the dried peels into coarse particles; and
subjecting the ground peel to extraction by hydro-distillation or Soxhlet extraction.
2. The method as claimed in claim 1, wherein hydro-distillation is carried out by mixing 200 g of fresh kinnow peel with 500 ml of water and 50 g of mechanically and solarly dried peel powder with 200 ml of water in a round-bottomed flask, and heating the mixture at 70°C for 3 to 4 hours until oil extraction is complete.
3. The method as claimed in claim 1, wherein Soxhlet extraction is carried out by placing 50 g of crushed kinnow peel into a cellulose thimble, using 200 ml of acetone as the solvent, maintaining the extraction at 65°C under continuous reflux for 6 hours, and recovering the essential oil by concentrating the extract in a rotary evaporator.
4. The method as claimed in claim 1, wherein the crushing of dried kinnow peel is performed to increase surface area and improve extraction efficiency during both hydro-distillation and Soxhlet extraction processes.
5. The method as claimed in claim 1, wherein the essential oil yield obtained from hydro-distillation and Soxhlet extraction is measured and compared to determine the more effective and efficient method for essential oil recovery from kinnow peel.