Dried fish are susceptible to bacteria and fungi attack and are liable to chemical changes which cause losses in quality and reduction of shelf-life. It is important therefore to maintain the quality of fish because c...Dried fish are susceptible to bacteria and fungi attack and are liable to chemical changes which cause losses in quality and reduction of shelf-life. It is important therefore to maintain the quality of fish because continuous consumption of contaminated fish and their products may predispose consumers to health hazards. Maintenance of high quality fish therefore calls for adequate and effective preservation techniques. The study examined the effectiveness of essential oils of Ocimum basilicum and Ocimum gratissimum from two Agro-ecological zones of Cameroon in limiting the microbial proliferation and preserving the quality of smoke-dried Oreochromis niloticus fish stored at 25˚C for two months. The plant materials were harvested from the Western Highlands and Monomodal Humid Forest agroecological zones of Cameroon. Extraction of the essential oil from the plants was done by hydro-distillation. The fish species (Oreochromis niloticus) used in this study was chosen based on a survey study on the most consumed species of freshwater smoke-dried fish in the Western Highlands and Monomodal Humid Forest Agro-ecological zones of Cameroon. Heterotrophic bacteria counts, fungi counts and Enterobacteriaceae counts were used to assess the level heterotrophic bacteria, fungi and Enterobacteriaceae respectively in the fish samples during storage and were done by culture techniques using total plate count agar, potato dextrose agar and violet red bile glucose agar respectively. Total volatile basic nitrogen, peroxide value, and thiobarbituric acid reactive substance assays were used as spoilage indices to assess the nutritional quality of the fish during storage. From the survey study, Oreochromis niloticus was the most consumed smoke-dried fish in the Western Highlands (35.45%) and Monomodal Humid Forest (34.55%) agroecological zones. All the EOs caused a significant reduction in the microbial loads, total volatile basic nitrogen, peroxide value, and thiobarbituric acid reactive substance of smoke-dried Oreochromis niloticus as storage progressed. However, the reduction in these values was more pronounced in samples treated with essential oils of O. gratissimum from the Western Highlands, with heterotrophic bacteria, fungi and Enterobacteriaceae counts being 5.89, 6.97 and 4.59 log<sub>10</sub> cfu/g respectively at the end of the storage period. This was followed by essential oils of O. gratissimum from the Monomodal Humid Forest with heterotrophic bacteria, fungi and Enterobacteriaceae counts being 6.11, 7.79 and 4.86 log<sub>10</sub> cfu/g respectively at the end of the storage period. Also, essential oils of O. gratissimum from the Western Highlands was more effective in preserving the fish quality as lowest total volatile basic nitrogen (12.29 mg/100g), peroxide value (2.79 mEq O<sub>2</sub>·Kg<sup>−1</sup>) and thiobabituric reactive substance (1.695 mg MDA/Kg) values were observed for fish samples treated with this extract at the end of the storage period. This was followed by essential oils of O. gratissimum from the Monomodal Humid Forest with total volatile basic nitrogen (14.95 mgN/100g), Peroxide value (3.23 mEq O<sub>2</sub>·Kg<sup>−1</sup>) and thiobabituric reactive substance (2.354 mg MDA/Kg) at the end of the storage period. From the results obtained, essential oils from O. gratissimum were more effective than that from O. basilicum in the two agroecological zones and should be considered as natural alternative to chemical preservatives for further application in food preservation.展开更多
Objective:To carry out a phyto-chemical characterization of essential oil from Ocimum basilicum L.(O.basilicum) harvested in DR Congo and to assess the antioxidant potential of crude extracts with respect to the polar...Objective:To carry out a phyto-chemical characterization of essential oil from Ocimum basilicum L.(O.basilicum) harvested in DR Congo and to assess the antioxidant potential of crude extracts with respect to the polarity for comparison reason.Methods:The phyto-chemical characterization of essential oil produced by hydrodistillation was performed by coupled gas chromatography-mass spectrometer analysis and the antioxidant potential evaluation by in vitro 2,2-diphenyl-1-picrylhydrazyl free radical scavenging activity method.Results:A previously weighed amount of fresh leaves of O.basilicum produced 0.65%of essential oil that led to the identification of a set of 84.44%out of 99.98%as major compounds(> 1.5%).The chemo-type of this essential oil was linalool-methyl chavicol.Chemical components of oil were characterized by oxygenated aromatic hydrocarbons(46.00%) and oxygenated monoterpenes(26.75%).With respect to the amount of components,methyl chavicol also known as estragole(35.72%) constituted the very large quantity afterward linalool(21.25%) and then epi-α-cadinol(8.02%),α-bergamotene(6.56%),eugenol(4.60%),1,8-cineole(4.04%),germacrene D(2.06%),thymol(1.64%),and(E)-citral(1.55%),respectively.Essential oil exhibited antioxidant potential and IC_(50) =(1.180 ± 0.015) mg/mL.Non-polar crude extracts yields were low compared to the one of polar extracts.Only methanol and ethyl acetate had considerably manifested antioxidant potential with IC_(50) values equal to(0.025 ± 0.013) mg/mL and(0.085 ± 0.012) mg/mL,respectively.As concerns to IC50 values,essential oil was less active than methanol and ethyl acetate extracts.The methanol crude extract exhibited the highest activity.Non-polar extracts showed insignificant radical scavenging ability that did not allow assessing IC50 values.These results highlighted the occurrence of antioxidant potential compounds in polar media.Conclusions:Essential oil and crude extracts of O.basilicum growing in DR Congo can be advocated as natural sources of antioxidant potential compounds not only in food but also in pharmaceutical industries.The high antioxidant potential of polar crude extracts highlights antioxidant character of its composition particularly butyl stearate and rosmarinic acid we isolated and identified,respectively in the methanol crude extract.展开更多
Sweet basil (Ocimum basilicum L.) project that is being conducted at the National Oilseed Processing Research Institute (NOPRI) aims at exploiting the genetic diversity and associated phenotypic variation in the inves...Sweet basil (Ocimum basilicum L.) project that is being conducted at the National Oilseed Processing Research Institute (NOPRI) aims at exploiting the genetic diversity and associated phenotypic variation in the investigated basil germplasm and evaluating key factors such as variety, plant ontogeny and plant parts that affect yield, chemical constituents, aroma and flavor of essential oils. This paper discussed the variability inessential oils content and chemical constituents of the aerial plant parts of the basil. An open-air pot experiment was carried out using three accessions provided by Agricultural Research Corporation-Genetic Resources Unit, Sudan. The essential oils were hydro distilled from the aerial parts, flowers, leaves, stems, using Clevenger apparatus. The chemical constituents of the essential oils were determined by Gas Chromatography-Mass Spectrometry (GC-MS). As the hydro distillation yielded no oil from the stem, we present only the results for leaves and flowers. The results revealed that the essential oil content varied with a range of 0.29% to 0.33% for flowers and 0.32% to 0.48% for leaves. As usual, the content of essential oils was higher in leaves than in flowers. The Silate-Egyptian accession had the lowest essential oil content obtained from leaves and flowers. However, South Darfur accession from Sudan had the highest oil content but did not significantly differ from Kennana accession. Several oil components were identified based upon comparison of their mass spectral data with those of reference compounds published in literature or stored in a computer library. The combined GC-MS analysis showed that methyl eugenol was the major constituent of the essential oil of Kennana accession. While the major constituent of essential oil of South-Darfur and Silate-Egyptian accessions were germacrene and linalool, respectively.展开更多
文摘Dried fish are susceptible to bacteria and fungi attack and are liable to chemical changes which cause losses in quality and reduction of shelf-life. It is important therefore to maintain the quality of fish because continuous consumption of contaminated fish and their products may predispose consumers to health hazards. Maintenance of high quality fish therefore calls for adequate and effective preservation techniques. The study examined the effectiveness of essential oils of Ocimum basilicum and Ocimum gratissimum from two Agro-ecological zones of Cameroon in limiting the microbial proliferation and preserving the quality of smoke-dried Oreochromis niloticus fish stored at 25˚C for two months. The plant materials were harvested from the Western Highlands and Monomodal Humid Forest agroecological zones of Cameroon. Extraction of the essential oil from the plants was done by hydro-distillation. The fish species (Oreochromis niloticus) used in this study was chosen based on a survey study on the most consumed species of freshwater smoke-dried fish in the Western Highlands and Monomodal Humid Forest Agro-ecological zones of Cameroon. Heterotrophic bacteria counts, fungi counts and Enterobacteriaceae counts were used to assess the level heterotrophic bacteria, fungi and Enterobacteriaceae respectively in the fish samples during storage and were done by culture techniques using total plate count agar, potato dextrose agar and violet red bile glucose agar respectively. Total volatile basic nitrogen, peroxide value, and thiobarbituric acid reactive substance assays were used as spoilage indices to assess the nutritional quality of the fish during storage. From the survey study, Oreochromis niloticus was the most consumed smoke-dried fish in the Western Highlands (35.45%) and Monomodal Humid Forest (34.55%) agroecological zones. All the EOs caused a significant reduction in the microbial loads, total volatile basic nitrogen, peroxide value, and thiobarbituric acid reactive substance of smoke-dried Oreochromis niloticus as storage progressed. However, the reduction in these values was more pronounced in samples treated with essential oils of O. gratissimum from the Western Highlands, with heterotrophic bacteria, fungi and Enterobacteriaceae counts being 5.89, 6.97 and 4.59 log<sub>10</sub> cfu/g respectively at the end of the storage period. This was followed by essential oils of O. gratissimum from the Monomodal Humid Forest with heterotrophic bacteria, fungi and Enterobacteriaceae counts being 6.11, 7.79 and 4.86 log<sub>10</sub> cfu/g respectively at the end of the storage period. Also, essential oils of O. gratissimum from the Western Highlands was more effective in preserving the fish quality as lowest total volatile basic nitrogen (12.29 mg/100g), peroxide value (2.79 mEq O<sub>2</sub>·Kg<sup>−1</sup>) and thiobabituric reactive substance (1.695 mg MDA/Kg) values were observed for fish samples treated with this extract at the end of the storage period. This was followed by essential oils of O. gratissimum from the Monomodal Humid Forest with total volatile basic nitrogen (14.95 mgN/100g), Peroxide value (3.23 mEq O<sub>2</sub>·Kg<sup>−1</sup>) and thiobabituric reactive substance (2.354 mg MDA/Kg) at the end of the storage period. From the results obtained, essential oils from O. gratissimum were more effective than that from O. basilicum in the two agroecological zones and should be considered as natural alternative to chemical preservatives for further application in food preservation.
基金Supported by Longjin Company Sarl for the Research Grant(DD Tshilanda LCS/1020-SU-160710)Organization for the Prohibition of Chemical Weapons for the Training Grant(Ref.S/1295/2015)
文摘Objective:To carry out a phyto-chemical characterization of essential oil from Ocimum basilicum L.(O.basilicum) harvested in DR Congo and to assess the antioxidant potential of crude extracts with respect to the polarity for comparison reason.Methods:The phyto-chemical characterization of essential oil produced by hydrodistillation was performed by coupled gas chromatography-mass spectrometer analysis and the antioxidant potential evaluation by in vitro 2,2-diphenyl-1-picrylhydrazyl free radical scavenging activity method.Results:A previously weighed amount of fresh leaves of O.basilicum produced 0.65%of essential oil that led to the identification of a set of 84.44%out of 99.98%as major compounds(> 1.5%).The chemo-type of this essential oil was linalool-methyl chavicol.Chemical components of oil were characterized by oxygenated aromatic hydrocarbons(46.00%) and oxygenated monoterpenes(26.75%).With respect to the amount of components,methyl chavicol also known as estragole(35.72%) constituted the very large quantity afterward linalool(21.25%) and then epi-α-cadinol(8.02%),α-bergamotene(6.56%),eugenol(4.60%),1,8-cineole(4.04%),germacrene D(2.06%),thymol(1.64%),and(E)-citral(1.55%),respectively.Essential oil exhibited antioxidant potential and IC_(50) =(1.180 ± 0.015) mg/mL.Non-polar crude extracts yields were low compared to the one of polar extracts.Only methanol and ethyl acetate had considerably manifested antioxidant potential with IC_(50) values equal to(0.025 ± 0.013) mg/mL and(0.085 ± 0.012) mg/mL,respectively.As concerns to IC50 values,essential oil was less active than methanol and ethyl acetate extracts.The methanol crude extract exhibited the highest activity.Non-polar extracts showed insignificant radical scavenging ability that did not allow assessing IC50 values.These results highlighted the occurrence of antioxidant potential compounds in polar media.Conclusions:Essential oil and crude extracts of O.basilicum growing in DR Congo can be advocated as natural sources of antioxidant potential compounds not only in food but also in pharmaceutical industries.The high antioxidant potential of polar crude extracts highlights antioxidant character of its composition particularly butyl stearate and rosmarinic acid we isolated and identified,respectively in the methanol crude extract.
文摘Sweet basil (Ocimum basilicum L.) project that is being conducted at the National Oilseed Processing Research Institute (NOPRI) aims at exploiting the genetic diversity and associated phenotypic variation in the investigated basil germplasm and evaluating key factors such as variety, plant ontogeny and plant parts that affect yield, chemical constituents, aroma and flavor of essential oils. This paper discussed the variability inessential oils content and chemical constituents of the aerial plant parts of the basil. An open-air pot experiment was carried out using three accessions provided by Agricultural Research Corporation-Genetic Resources Unit, Sudan. The essential oils were hydro distilled from the aerial parts, flowers, leaves, stems, using Clevenger apparatus. The chemical constituents of the essential oils were determined by Gas Chromatography-Mass Spectrometry (GC-MS). As the hydro distillation yielded no oil from the stem, we present only the results for leaves and flowers. The results revealed that the essential oil content varied with a range of 0.29% to 0.33% for flowers and 0.32% to 0.48% for leaves. As usual, the content of essential oils was higher in leaves than in flowers. The Silate-Egyptian accession had the lowest essential oil content obtained from leaves and flowers. However, South Darfur accession from Sudan had the highest oil content but did not significantly differ from Kennana accession. Several oil components were identified based upon comparison of their mass spectral data with those of reference compounds published in literature or stored in a computer library. The combined GC-MS analysis showed that methyl eugenol was the major constituent of the essential oil of Kennana accession. While the major constituent of essential oil of South-Darfur and Silate-Egyptian accessions were germacrene and linalool, respectively.
