INTRODUCTION:

Humans have used plant extracts for numerous benefits^1–3. Traditional practices still employ substances such as wood tar^4–6, which persist in various countries, including Morocco^7,8. Wood tar and essential oils are natural substances obtained through the pyrolysis and hydrodistillation of plant materials⁷.

These versatile extracts find applications in cosmetics, medicine, and pharmacy ^8–11.

In the investigation into the valorization of wood tar, samples of wood tar fromCedrus atlantica and Juniperus oxycedrus were studied, as these are the main species used in tar production in Morocco^7,12,13. Cedarwood oil, with proven efficacy against various microbes, holds ancient medicinal value¹⁴. The Juniperus genus serves multifaceted purposes, such as a spice and alcoholic beverage flavoring, cosmetics ingredient, and a pivotal medicinal plant in traditional treatments for diabetes, diarrhea, bronco-pulmonary ailments, and rheumatism¹⁵.

According to the World Health Organization, 80% of the global population relies on plants in traditional medicine¹⁶. Aromatic and medicinal plants, constituting 80000 of 500000 species worldwide, possess pharmacological potential against diseases, including cancer. The human pharmacopeia features 20000-25000 plants, with 75% possessing medicinal properties, and 25% containing bioactive compounds. With its rich biodiversity, Morocco encompasses 40000 plant speciesand is a key market for aromatic and medicinal plants¹⁷. The medicinal properties of plants stem from secondary metabolites, influenced by intrinsic and extrinsic factors, leading to qualitative and quantitative changes¹⁸.

The study focused on wood tar from three different sources: those collected from cooperatives, those purchased from traditional herbalists, and those produced at the laboratory level. This research investigates the characteristics of wood tars derived from cedar and juniper wood in Morocco through pyrolysis processes, with a primary focus on humidity, yield, color, smell, density, and pH. The objective is to study the physicochemical properties of wood tars, contributing to a deeper understanding of these products and facilitating the development of innovative applications.

MATERIALS AND METHODS:

Plant materials:

The plant material used in this study was supplied and collected from local cooperatives in Morocco. The stumps of Cedrus atlantica wood were collected from the Itzer forestry cooperative in June 2021, while the Juniperus oxycedrus wood was supplied by the Talgount forestry cooperative in March 2021¹⁹. Before preparing wood tar, the plant material samples were cleaned and cleared of all foreign bodies. The plant material was then cut into small pieces using a wood axe to facilitate further processing by pyrolysis.

Artisanal wood tar:

Artisanal wood tar was supplied by local producers who prepared it by dry distillation using traditional techniques²⁰. The wood tar sample from C. atlantica was produced using a directly fired charcoal kiln. The J. oxycedrus tar was produced by another process, namely the indirect combustion kiln. The two cooperatives leave the tar to settle to separate the aqueous and oily phases of the tar .

Laboratory wood tar:

Laboratory wood tar was produced in the Wood Technology Laboratory in May-June 2021. Wood cut into small pieces was placed in an iron container and put in a pyrolysis apparatus (Pyrox brand) equipped with a cooling system. The temperature was set at 450 degrees Celsius²¹, and after 3 to 4 hours, tar was obtained as a result in the distillation flask.

Commercial wood tar:

Commercial wood tar was purchased from herbalists, and there are two types. The first type is sold by quantity, depending on the consumer's needs. This type of tar is usually packaged in a glass or plastic bottle or plastic bag. The second type of tar is sold in small bottles (Figure 1).

Figure 1: a) Traditional wood tar production technique; b) Laboratory wood tar production process c) Commercial wood tar sold by herbalists

Relative density at 20°c:

The samples' relative density (d20) is obtained by calculating the ratio between the density of wood tar and that of distilled water^22,23.

pH:

The pH of wood tar was determined by a pH meter (Eutech Instruments Waterproof Cyberscan PH 310)^22–24.

Statistics analysis:

The data were analyzed using GraphPad Prism 9.5.0 software. A probability value of 5% (p ≤ 0.05) was considered statistically significant for determining the significance of differences between mean values. Multiple statistical tests were utilized for the analysis, including descriptive statistics, multiple unpaired t-tests, and the Mann-Whitney test.

RESULT AND DISCUSSION:

Extraction:

Wood tar was produced form C. atlantica and J. oxycedrus. During pyrolysis, three phases are formed: an aqueous phase, initially present in the biomass or resulting from its degradation reactions, containing water-soluble organic molecules, which is named "tar water" (TW); An organic phase, insoluble in water, called tar (T), and a gaseous phase²⁵.

Yield:

In the literature, it is stated that approximately 5.71 kilograms of wood are needed to make one liter of tar²⁶. According to a study conducted by Bellakhdar (1997), producing approximately half a liter of wood tar requires the equivalent of a full 10-liter jar of wood²⁷. Another study conducted in Turkey revealed that about 2.44 kilograms of wood is required to produce one liter of tar⁶. In the traditional method used in Turkey, dry softwood from large stumps of dead trees is considered good for tar production because it is highly resinous⁵.

In the laboratory, wood tar was extracted from 1.2 kilograms of wood for each species. A yield of 530 ml of wood tar was obtained from C. atlantica, representing 65% of the liquid obtained, and 220 ml for the juniper tar, representing 38% (Figure). Thus, to produce one liter of tar, it would be necessary to use 2.3 kilograms of C. atlantic and 5.4 kilograms of J. oxycedrus.

Figure 2: Pyrolysis yields and wood moisture content results

In Morocco, El Jemli (2020) conducted tar preparation in the laboratory through the carbonization of 100g branches from various selected species within a flask. The lowest tar yield was obtained with J. oxycedrus, at a rate of 2.76%. Other tar yields were as follows: Juniperus thurifera provided the highest yield, at 8.52%, followed by Tetraclinis articulata with a yield of 7.12%, while Juniperus phoenicea yielded 3.32%²⁸.

In Algeria, Larbi (2019) performed wood tar extraction using the dry distillation technique in the laboratory with an inverted casserole. Bunsen burners heated the wood for six hours until complete carbonization. The tar extraction yields of three species were obtained 0.549% for J. oxycedrus, 0.703% for Acacia raddiana, and 0.542% for J.phoenicea²³.

The proportion of tar produced depends on several factors, including the production method. According to Bellakhdar (1997), the confined incomplete combustion method is considered the most efficient, offering the best yield when dead trees are used. Additionally, several production method variations exist⁷. The proportion of tar obtained varies from 20% to 60% of the weight of dry wood⁶.

The temperature for the extraction process in the study was set at 450°C. During the temperature rise to 380-390°C, a white fumigation was formed, which evolved into a brown coloration over time and with the temperature rise. The smoke then condensed to form droplets, the rate of which accelerated over time.

In the study by Takci (2019), the combustion process started with igniting pieces of wood, followed by a high average temperature of 400°C for 1 to 2 hours to obtain a better tar yield²⁹. The extraction temperature is also a key factor for tar production from softwood. High temperatures (above 200°C) are necessary for good quality tar³⁰. According to Kurt & Isik (2012), traditional methods involve a gradual increase in temperature until exceeding 300°C, which impacts the tar's chemical composition and leads to significant variations in the final product⁵. However, the tar yield is significantly higher at low temperatures than at high temperatures (1100°C)³¹. Heating and burning time are also crucial in the production of tar. In traditional methods, the burning time can be up to 2-15 days, while in modern laboratory methods, the extraction process is much shorter. However, a slow and gradual combustion process obtains a higher quality tar. Tar quality can be assessed by its viscosity and odor⁵.

These results show that tar yields can vary considerably depending on the plant species used, the quality of the wood, as well as the production method. In addition, the extraction temperature and burning time are vital in influencing the quantity and quality of the tar produced. The results ofthe moisture are shown in the figure below. For C. atlantica, the moisture content of the wood was 2.40±0.01%. while J. oxycedrus, the results reveal that the moisture content of the wood was 9.27±0.01%, thus demonstrating more significant moisture compared to C. atlantica

A significant difference in the moisture content of the wood is observed when comparing the results of C. atlantica and J. oxycedrus. This variance may have impacted the volume of wood tar obtained, suggesting that high moisture levels in the wood can significantly influence the volume of wood tar extracted, and consequently, the pyrolysis yield. This observation aligns with a study by Derriche et al. (2015), highlighting the importance of plant nature and physiology in the quantity of extracted essential oils³². Moreover, further studies are needed to elucidate this correlation.

Color aspect:

In this part of the study, the objective was to visualize wood tars. Regarding the color aspect of the tars purchased from herbalists, as shown in Figure, the coloring varies from light black to gray, passing through light brown, dark brown, and shiny black. Most tars exhibit a glossy appearance. Additionally, various appearances that could theoretically be considered fake wood tar were observed, such as those exhibiting heterogeneity. Concerning the homogeneity of tar, cedar tar has been described as a homogeneous liquid³³. Similarly, real cade oil is described as a thick and homogeneous liquid with a specific odor³⁰.

Figure 3: Color variation of a) Commercial, b) Artisanal and laboratory wood tar

Other studies have also highlighted color differences among various types of tars. Cade oil is typically described as blackish^23,30, while cedar tar tends to exhibit a reddish-brown³³. Yellow wood tar is mainly obtained from Juniperus spp and Cedrus libani, whereas black tar is obtained from Pinus nigra subsp. Pallasiana and Pinus brutia⁴. Furthermore, during the production process, it was observed that the dark black color of the tar originates from resinous roots, while the yellow color is derived from branches⁴.

In comparing wood tars obtained from two different sources, C. atlantica and J. oxycedrus noticeable differences in color were observed. To facilitate the visualization of these differences, the samples were placed side by side. It was noted that the cedar tar obtained from the cooperative appeared darker than that obtained in the laboratory. Conversely, the juniper tar appeared denser and black, whereas the laboratory-obtained tar exhibited a dark brown coloration.

Smell:

All samples, without exception, emit a very strong smell that is characteristic of them. The tars from the cooperative and the laboratory exhibit a characteristic odor of the species, particularly that which originates from C. atlantica. Regarding the smell, it has been reported that tars possess a specific odor, especially in cade oil^23,30, Cedar tar, in particular, is known for its strong and distinctive empyreumatic smell, often making it a preferred substitute for cade oil³³ .

Relative density at 20°C:

The results of Commercial wood tar are represented in Figure (a) and the appendix. The maximum relative density for liquid tars was 1.069±0.084, with a minimum value of 0.775±0.019 and an average of 0.929±0.0677. For thick tars, the maximum value was 1.195±0.103 and the minimum value was 0.837±0.167, with an average of 1.039±0.0886. The Mann-Whitney test, also known as the Wilcoxon-Mann-Whitney test, was employed to compare the two independent samples of different sizes, liquid (24 samples) and thick (21 samples) tars. In this case, the Mann-Whitney test evaluated the null hypothesis that there is no difference between the medians of the two samples. A "P-value of 0.0001" was obtained, which is lower than the critical value of the alpha generally fixed at 0.05. This indicates a significant difference between the two thick and liquid tar samples.

The relative density of the cedar and juniper artisanal and laboratory wood tar is illustrated in Figure(b). Basic statistical tests revealed that the average cedar tar density was 0.906±0.023 for the artisanal wood tar and 0.966±0.002 for the laboratory wood tar. For juniper, the average density was 1.179±0.017 for the artisanal wood tar and 1.081±0.004 for the laboratory wood tar. To compare the densities of the cooperative and laboratory tars for each species, an unpaired t-test was employed. This test compares the means of two independent groups. The null hypothesis for this test is that the means of the two groups are equal. The P values for cedar and juniper tar were 0.0104 and 0.0006, respectively. Both values of P being less than 0.05, the null hypothesis is rejected. Therefore, it can be concluded that the averages of the artisanal and laboratory wood tar are significantly different for the two species of C. atlantica and J. oxycedrus.

Liquid and thick wood tars from commercial, artisanal, and laboratory sources were compared by calculating the averages for each type. Cedar tar was categorized as liquid, while juniper tar was identified as thick. The results are presented in Figure(c). Multiple unpaired t-tests were employed to compare the means of commercial, artisanal, and laboratory wood tar in the analysis. This method involves conducting multiple unpaired t-tests for each pair of groups (liquid and thick tars) to assess whether the means of each group differ significantly. The p-values for artisanal, laboratory, and commercial tars were 0.0001, <0.0001, and 0.0517, respectively. The p-values for thick and liquid artisanal and laboratory wood tars were all below 0.05, indicating significant differences in means. Conversely, for tars from herbalists, the p-value was 0.0517, suggesting non-significant differences in means. Our study's findings revealed that the relative densities of C. atlantica and J. oxycedrus tar from the cooperative were 0.906±0.023 and 1.179±0.017, respectively. Meanwhile, for laboratory tars, the densities were 0.966±0.002 and 1.081±0.004, respectively.

Figure 4: Relative density at 20°C for a) Commercial wood tar purchased from herbalists; b)Artisanal and laboratory wood tar; c) Comparison

In Larbi's studies, it was found that the density of tar marketed in the Wilaya of Bechar in southern Algeria varies from 0.870 to 1.025.³⁴ Wood tar density ranges from 0.95 to 1.03 at 20°C, as indicated in the same study.³⁴ Additionally, Larbi's research reports the density of cade oils to be between 0.9 and 1 at 20°C²³, while J. oxycedrus tar has a density of 1.15.³⁵ According to Belliot, the relative density of J. oxycedrus tar varies from 0.970 to 1.055.³⁰

The density of tars from C. atlantica and J. oxycedrus obtained through artisanal methods was observed to be higher than that of commercially marketed tars in the Wilaya of Bechar, as well as higher than the tar of J. oxycedrus reported by Belliot. Conversely, the density of laboratory-produced tars was slightly higher than that of cade oils reported by Larbi²³. Kurt and Isik suggest that traditional tar production techniques may yield superior quality compared to modern laboratory methods, which, although faster ³⁶may result in an inferior product⁵.

Compared to wood tar from other species, the density of pine tar is 1.065³⁰, while that of A.raddiana taris 1.154^23,37. Additionally, the density of Olea europaea subsp. sylvestris Taris 1.08³⁸. These results suggest that density alone does not conclusively identify the type of tar, as it can vary based on the species, preparation methods, and other conditions^23,39.

pH Measurements:

Measurements of tar purchased from herbalists are shown in Figure (a). A descriptive statistical test was conducted. The number of samples of the thick tar and the liquid tar was 21 and 24, respectively. The maximum pH value measured in the thick tar was 4.393±0.121, the minimum value was 2.963±0.441, and the average was 3.449±0.410. Regarding the liquid tar, a maximum value of 4.403±0.256 was obtained, a minimum of 2.507±0.259, and an average of 3.313±0.503. A Mann-Whitney test was utilized to compare the pH results of liquid and thick tars. In this case, the null hypothesis is that there is no difference between the two samples. A value of 0.2959 was obtained, which is higher than the critical alpha value, generally set at 0.05. This indicatesthat there is no significant difference between the pH of thick and liquid tars.

The results of pH measurements for wood tars obtained from cooperative and laboratory settings are presented in Figure (b). Significant differences in pH levels are observed between the tars of C. atlantica and J. oxycedrus between the cooperative and the laboratory. For the C. atlantica tar, the average pH was 1.280±0.020 for artisanal production and 2.297±0.025 for laboratory production. For J. oxycedrus tar, the average pH was 3.500±0.072 for artisanal production and 1.913±0.042 for laboratory production. The average pH value for the C. atlantica tar is significantly higher for the laboratory wood tar (2.297±0.025) than for the artisanal wood tar (1.280±0.020). Conversely, J. oxycedrus, showed higher pH in artisanal samples (3.500±0.072) than in laboratory samples (1.913±0.042). This difference could be attributed to variations in sample preparation methods. which can affect pH levels in both artisanal and laboratory-produced wood tars. To compare the pH values of the cooperative and laboratory tars for each species, an unpaired t-test was conducted. The null hypothesis for this test is that the mean pH values of the two groups were unequal. The test results showed a P value of 0.1000 for both C. atlantica and J. oxycedrus tars samples, indicating a significant difference in means between the two species. These results indicate a significant difference between the pH values of artisanal and laboratory wood tars for each species.

The comparison data is presented in Figure (c). which illustrates the means and standard deviations of pH measurements of thick and liquid wood tar for artisanal, laboratory, and commercial. In the case of the thick sample (J. oxycedrus), an average pH of 3.500±0.072 is observed for artisanal wood tar, whereas the laboratory wood tar sample demonstrates an average of 1.913±0.042. For the liquid sample (C. atlantica), the average pH of the artisanal wood tar is 1.280±0.020, compared to 2.297±0.025 for the laboratory. As for commercial wood tar samples, the average pH for the thick sample is 3.449±0.155, while the liquid sample registers an average pH of 3.313±0.337.

In the study, pH values of the tar samples varied between different sources. For the thick sample (J.oxycedrus), the average pH value of the artisanal wood tar is higher than that of laboratory wood tar, with a difference of 1.587. Similarly, for the liquid sample (C. atlantica), the average pH of artisanal wood tar was lower than that of laboratory wood tar, with a difference of 1.017. However, commercial wood tar samples show similar pH averages, with a difference of only 0.136 between the thick and liquid samples.

Multiple unpaired t-tests were utilized to compare the means of artisanal, laboratory, and commercial wood tars. This statistical method involves conducting unpaired t-tests for liquid and thick tars to determine whether significant differences exist in the means of each group. The results of the multiple unpaired t-tests indicated differences in pH values between artisanal and laboratory tar samples, with respective p-values of 0.0001 and 0.0005. The p-values for thick and liquid samples from the cooperative and the laboratory were below 0.05, indicating a significant differencein pH values for these samples. Conversely, for commercial tar samples, the p-value stood at 0.5740, surpassing the 0.05 threshold. This value implies the absence of significant differences in pH values between herbalist thick and liquid samples.

Figure 5: pH Measurement of a) Commercial wood tar purchased from herbalists; b) Artisanal and laboratory wood tar; c) Comparison

The acidity levels of J. oxycedrus tar have been reported as 3.25³⁵ and 5.66²³. However, various studies have indicated differing pH levels for different types of wood tar. For instance, O. europaea tar was found to have a pH of 3.7³⁸, while A. raddiana tar showed a pH of 5.2³⁷. Tar marketed in Algeria showed a pH of 6.59³⁴. Furthermore, it has been observed that the acidity of the products can be influenced by the oxygen content, as evidenced in the findings of Rocha de Castro et al. (2021) concerning pyrolysis seeds²¹.

CONCLUSION:

The study focused on the extraction and characterization of wood tar properties obtained from pyrolysis. Examination of tar preparation methods via pyrolysis, alongside assessment of organoleptic characteristics such as color and odor, measurements of moisture, yield, relative density, and pH were conducted. The results revealed significant differences in yield, relative density, coloration, and pH for C. atlantica and J. oxycedrus tars between the cooperative and the laboratory. Testing of organoleptic characteristics was visual, indicating the necessity of incorporating more rigorous testing methods to evaluate these properties. This highlights the importance of comprehending diverse wood tar preparation methods and the factors impacting their properties. The study lays a foundation for future tar research. Additional investigation is required to better understand density variations among wood tar from different plant sources and species under varied extraction conditions, and to optimize tar preparation techniques for enhanced utilization across multiple sectors such as medicine and industry.

CONFLICT OF INTEREST:

The authors have no conflicts of interest regarding this investigation.

ACKNOWLEDGMENTS:

Special thanks are extended to the Forest Research Center - Rabat in Morocco for providing the necessary technical facilities to conduct this research and for the valuable support of the research team. Sincere appreciation is extended to Mr. Said and Mr. Moulay Ahmed, responsible for the Talgount and Itzer cooperatives, respectively, for their generous cooperation.

REFERENCES:

1. Namrta Choudhary, M.B. Siddiqui, Sayyada Khatoon. Variation in Extract Yield in Different Parts of Tinospora cordifolia. Res J Pharmacol Pharmacodyn. 2014; 6(1): 1–4.

2. Profile SEE. Medicinal Plants Used In Traditional Treatment of Hypertension in Turkey. Int J Sci Technol Res. 2020; (March). https://doi.org/10.7176/jstr/6-03-11

3. Sundar RD V., Settu S, Shankar S, Segaran G, Sathiavelu M. Potential Medicinal Plants to Treat Leprosy-A Review. Res J Pharm Technol. 2018; 11(2): 813–821. https://doi.org/10.5958/ 0974-360X.2018.00153.1

4. Ari S, Kargioǧlu M, Temel M, Konuk M. Traditional Tar Production from the Anatolian Black Pine [Pinus nigra Arn. subsp. pallasiana (Lamb.) Holmboe var. pallasiana] and its usages in Afyonkarahisar, Central Western Turkey. J Ethnobiol Ethnomed. 2014; 10(1): 1–9. https://doi.org/10.1186/1746-4269-10-29

5. Kurt Y, Isik K. Comparison of tar produced by traditional and laboratory methods. Stud Ethno-Medicine. 2012; 6(2): 77–83. https://doi.org/10.1080/09735070.2012.11886423

6. Kurt Y, Suleyman Kaçar M, Isik K. Traditional tar production from Cedrus libani A. Rich on the Taurus Mountains in southern Turkey. Econ Bot. 2008; 62(4): 615–620. https://doi.org/10.1007/s12231-008-9023-x

7. Burri S, Alifriqui M, Bun S-S, et al. Des ressources naturelles à la santé : Approche interdisciplinaire de la production des goudrons de conifères et de leur usage médicinal en Méditerranée sur la longue durée. Les Nouv l’archéologie. 2018: 62–69. https://doi.org/10.4000/nda.4267

8. Ninich O, Et-tahir A, Kettani K, et al. Plant sources, techniques of production and uses of tar: A review. J Ethnopharmacol. 2022; 285(11): 114889. https://doi.org/10.1016/j.jep.2021.114889

9. Chauiyakh O, Fahime E El, Aarabi S, Ninich O. REVIEW ARTICLE A Systematic Review on Chemical Composition and Biological Activities of cedar Oils and Extracts. 2023; 16(August): 3875–3883. https://doi.org/10.52711/0974-360X.2023.00639

10. Koller J, Baumer U, Kaup Y, Schmid M, Weser U. Ancient materials: analysis of a pharaonic embalming tar. Nature. 2003; 425(6960): 784. https://doi.org/https://doi.org/10.1038/425784a

11. Ninich O, Fahime E El, Tiskar M, et al. Cedar tar as a green corrosion inhibitor for E24 steel in 1 M HCl solution: A comparative analysis of uncleaned and cleaned cedar tar. Int J Corros Scale Inhib. 2023; 12(4): 2142–2170. https://doi.org/ 10.17675/2305-6894-2023-12-4-38

12. Julin M. Tar production–traditional medicine and potential threat to biodiversity in the Marrakesh region. An ethnobotanical study. Uppsala University; 2008

13. Lindborg M. GC-MS analysis for Polyaromatic Hydrocarbons (PAH) in Moroccan medicinal tars. Uppsala University: Committee of Tropcial Ecology; 2009

14. Ramadass M, Thiagarajan P. Importance and applications of cedar oil. Res. J. Pharm. Technol. 2015; 8(12): 1714–1718. https://doi.org/10.5958/0974-360X.2015.00308.X

15. Bajes HR, Oran SA, Bustanji YK. Chemical Composition and Antiproliferative and Antioxidant Activities of Essential Oil from Juniperus phoenicea L. Cupressaceae. Res J Pharm Technol. 2022; 15(1): 153–159. https://doi.org/10.52711/0974-360X.2022.00025

16. Mahcene Z, Mahcene Z, Bireche K, Serdouk F. Socioeconomic valorization and development of a bio-fungicide from essential oils of four Algerian aromatic and medicinal plants: Artemisia herba alba Asso, Mentha pulegium L, Rosmarinus officinalis L and Ocimum basilicum L. Asian J Res Chem. 2020; 13(6): 473–484. https://doi.org/10.5958/0974-4150.2020.00084.x

17. Labiad H, Aljaiyash A, Ghanmi M, et al. Exploring the provenance effect on Chemical composition and Pharmacological bioactivity of the Moroccan essential oils of Laurus nobilis. Res J Pharm Technol. 2020; 13(9): 4067–4076. https://doi.org/10.5958/ 0974-360X.2020.00719.2

18. Joshi, R.K.; Joshi, B.C.; Sati MK. Chemical and chemotaxonomic aspects of some aromatic and medicinal plants species from Utrrakhand: a review. Asian J Pharm Technol. 2014; 4(3): 157–162.

19. Ninich O, El Fahime E, Satrani B, et al. Comparative Chemical and Biological Analysis of Wood and Tar Essential Oils from Cedrus atlantica and Juniperus oxycedrus in Morocco. Trop J Nat Prod Res. 2024; 8(3): 6570–6581. https://doi.org/10.26538/tjnpr/ v8i3.15

20. Ninich O, Et-tahir A, Kettani K, et al. Ethnobotanical knowledge of Moroccans about medicinal Tar. Trop J Nat Prod Res. 2022; 6(3): 317–329.

21. Rocha de Castro DA, da Silva Ribeiro HJ, Hamoy Guerreiro LH, et al. Production of fuel-like fractions by fractional distillation of bio-oil from açaí (Euterpe oleracea mart.) seeds pyrolysis. Energies. 2021; 14(13): 1–27. https://doi.org/10.3390/en14133713

22. International Organization for Standardization. ISO 279: 1998. Essential oils — Determination of relative density at 20 degrees C — Reference method. 1998.

23. Larbi B. Contribution à l’étude de Fusarium oxysporum f sp albedinis agent causal de la fusariose vasculaire du palmier dattier et moyens de lutte. Université Abdelhamid Ibn Badis De Mostaganem: Faculté des Sciences de la Nature et de la Vie,; 2019.

24. Gavarkar P, Adnaik R, Chavan D, Bagkar A, Bandgar R. Physicochemical investigation of some marketed herbal hair oil. Res. J. Top. Cosmet. Sci. 2016; 7(2): 70. https://doi.org/10.5958/ 2321-5844.2016.00011.x.

25. Donnot A. Craquage catalytique de goudron de pyrolyse du bois. Université Henri Poincaré - Nancy 1, 1989; 1989.

26. Ministère de l’Agriculture de la Pêche Maritime du Développement Rural et des Eaux et Forêts. Bilan d’activités Département des Eaux et Forêts Contrats Programmes 2018. 2018

27. Bellakhdar J. Contribution à l’étude de la pharmacopée traditionnelle au Maroc: la situation actuelle, les produits, les sources du savoir (enquête ethnopharmacologique de terrain réalisée de 1969 à 1992) TOME I. Université Paul Verlaine-Metz; 1997.

28. El Jemli M. Contribution à l’étude ethnobotanique, toxicologique, pharmacologique et phytochimique de quatre Cupressacées marocaines : Juniperus thurifera L., Juniperus oxycedrus L., Juniperus phoenicea L. et Tetraclinis articulata L. Université Mohammed V, Rabat; 2020.

29. Takci HAM, Turkmen FU, Sari M. In vitro mutagenic effect of cedar (Cedrus libani A. Rich) tar in the salmonella/microsome assay system. Banat J Biotechnol. 2019; X(November): 4738–12. https://doi.org/10.7904/2068.

30. Belliot A. Huile de cade, goudron de houille, ichthyol : utilisations dermatologiques et cosmétiques. Nantes; 2007.

31. Baker E, Brown M, Elliott DC, Mudge L. Characterization and treatment of tars from biomass gasifiers. AIChE 1988 Summer Natl Meet. 1988; 11.

32. Derriche R, Messaoudi S, Lahouazi N, Les R. Teneur en Polyphénols et Activité Antioxydante des Huiles Essentielles, Hydrolats et Extraits des Feuilles de l ’ Inulaviscosa (L .) Aiton d’ Algérie. 2015.

33. Aiboud A. Caractérisation phytochimique et étude de l’action antidermatophytique in vitro et in vivo du goudron de Cedrus atlantica, Nicotiana tabacum et Allium sativum L. Université Ibn Tofail; 2016.

34. Larbi B, Tahri U, Bechar M De, Ahmed M, Mebarki L. Analyse physico-chimique des goudrons végétaux commercialisés du sud ouest Algérien, et essai de leurs estimation de leurs activités antimicrobiennes. Int Agric Biotechnol Conf. Vol. 1. Bizerte Tunisia: 2015.

35. Terfaya B, Makhloufi A, Mekboul A, Benlarbi L, Abdelouahed D. Antifungal Activity of Juniperus oxycedrus Tar ; Growing Wild in North-west of Algeria. Appl Biol Sahar Areas. 2019; 1(January): 33–36.

36. Yadav AR, Mohite SK. Green chemistry approach for microwave assisted synthesis of some traditional reactions. Asian J Res Chem. 2020; 13(4): 261. https://doi.org/10.5958/0974-4150.2020.00051.6.

37. Mezouari A, Makhloufi A, Bendjima K, et al. Antifungal activity of Acacia tortilis subsp. raddiana tar on Fusarium oxysporum f.sp. albedinis, the cause of Bayoud disease of the date palm in Southwest Algeria. Indian J Agric Res. 2019; 53(6): 713–717. https://doi.org/10.18805/IJARe.A-417.

38. Bendjima K, Makhloufi A, Mezouari A, Makhloufi K. Antifungal activity of Olea europaea subsp. sylvestris tar against Fusari-um oxysporum f. sp. albedinis, the causal agent of Bayoud of the date palm in Southwest Algeria. South Asian J Exp Biol. 2020; 10(2). https://doi.org/10.38150/sajeb.10(2).p90-94.

39. Naryanto RF, Enomoto H, Cong AVAV, et al. The effect of moisture content on the tar characteristic of wood pellet feedstock in a downdraft gasifier. Appl Sci. 2020; 10(8). https://doi.org/ 10.3390/APP10082760.

Appendix

Appendix A: pH measurement and relative density of commercial, artisanal, and laboratory wood tar samples

Liquid wood Tar			Thick wood Tar
N°	Relative density	pH Measurements	N°	Relative density	pH Measurements
Commercial Wood Tar
1	0.966 ± 0.013	3.920 ± 0.061	1	1.079 ± 0.012	3.230 ± 0.381
2	0.960 ± 0.020	3.970 ± 0.509	2	0.994 ± 0.020	2.960 ± 0.441
3	0.978 ± 0.033	3.200 ± 0.731	3	1.074 ± 0.060	3.060 ± 0.115
4	0.798 ± 0.117	4.010 ± 0.600	4	0.977 ± 0.035	3.100 ± 0.057
5	0.824 ± 0.112	4.400 ± 0.256	5	1.063 ± 0.059	3.160 ± 0.326
6	0.953 ± 0.036	4.060 ± 0.682	6	1.124 ± 0.019	3.540 ± 0.391
7	0.923 ± 0.021	3.650 ± 0.291	7	0.988 ± 0.025	3.970 ± 0.151
8	0.924 ± 0.049	3.140 ± 0.284	8	0.964 ± 0.024	4.390 ± 0.121
9	0.867 ± 0.083	3.730 ± 0.157	9	0.900 ± 0.044	3.900 ± 0.242
10	0.976 ± 0.025	3.270 ± 0.546	10	1.081 ± 0.317	2.990 ± 0.085
11	0.775 ± 0.019	3.000 ± 0.229	11	1.050 ± 0.104	2.970 ± 0.049
12	0.934 ± 0.022	2.970 ± 1.271	12	1.081 ± 0.085	2.980 ± 0.682
13	0.973 ± 0.022	2.620 ± 0.376	13	1.005 ± 0.013	3.280 ± 0.410
14	0.931 ± 0.021	3.490 ± 0.650	14	0.943 ± 0.016	3.280 ± 0.544
15	0.900 ± 0.027	2.510 ± 0.259	15	1.000 ± 0.004	3.920 ± 0.345
16	0.956 ± 0.035	2.950 ± 1125	16	1.139 ± 0.031	3.400 ± 0.230
17	0.859 ± 0.081	3.380 ± 0.713	17	1.155 ± 0.050	3.680 ± 0.020
18	0.913 ± 0.119	3.100 ± 0.117	18	1.195 ± 0.103	3.770 ± 0.156
19	0.950 ± 0.154	3.330 ± 0.465	19	0.837 ± 0.167	3.380 ± 0.185
20	0.947 ± 0.188	3.110 ± 0.554	20	1.036 ± 0.069	3.510 ± 0.236
21	0.919 ± 0.137	2.730 ± 0.411	21	1.131 ± 0.015	3.930 ± 0.136
22	1.032 ± 0.162	2.940 ± 0.183	-	-	-
23	1.069 ± 0.084	2.740 ± 0.505	-	-	-
24	0.977 ± 0.036	3.340 ± 0.205	-	-	-
Average	0.929 ± 0.047	3.315 ± 0.337	Average	1.039 ± 0.008	3.449 ± 0.155
Cedar Tar			Juniper tar
Artisanal wood tar	0.906 ± 0.023	1.280 ± 0.020	Artisanal wood tar	1.179 ± 0.017	3.500 ± 0.072
Laboratory Wood Tar	0.966 ± 0.002	2.297 ± 0.025	Laboratory Wood Tar	1.081 ± 0.004	1.913 ± 0.042

Results are presented as mean ± SD for three determinations