Jemmy Takrama - Academia.edu (original) (raw)
Papers by Jemmy Takrama
Journal of the Ghana Science Association, 2003
Journal of the Ghana Science Association, 2004
Journal of the Ghana Science Association, Mar 1, 2000
Kola nuts wrapped with Mitragyna stipulosa (Akan: subaha) leaves and stored in baskets (tradition... more Kola nuts wrapped with Mitragyna stipulosa (Akan: subaha) leaves and stored in baskets (traditional method) and irradiated with Co-60 gamma rays with absorbed doses ranging from 0.10 to 0.50 kGy at a dose rate of 0.171 kGy/hr to control kola weevils (Balanogastris kolae) during storage. The number of nuts per treatment ranged between 20 and 1353, and the ambient storage temperature fluctuated between 16.5EC and 37.5E C. Gamma radiation suppressed the development and emergence of kola weevils that destroy the nuts in storage. Whilst no live insects were found in the treated samples, up to 48 live weevils were counted per packet in the control treatment at 28 days in storage. Consequently, nut infestation in the control was about 98.4%. Fungal deterioration of both irradiated and unirradiated kola nuts was observed. Weight loss in kola nuts irradiated at 0.25 and 0.50 kGy and stored for 84 days after irradiation was 18.2% and 19.2%, respectively, whilst comparable loss from the control treatment was 39.9%. Weevils fed with treated and untreated nuts did not show any preferences and differences in growth. A panel of tasters did not detect any differences between treated and untreated nuts. JOURNAL OF THE GHANA SCIENCE ASSOCIATION Volume 2 No. 3 (2000) pp. 184-192
![Research paper thumbnail of Responses of Recombinant Inbred Lines of Cowpea [(Vigna Unguiculata (L.) Walp] to Striga Gesnerioides Infestation in Ghana](https://attachments.academia-assets.com/111930563/thumbnails/1.jpg)
](European Scientific Journal, ESJ, Jul 12, 2013
Cowpea [Vigna unguiculata (L.) Walp.] production in West Africa is constraint by Striga gesnerioi... more Cowpea [Vigna unguiculata (L.) Walp.] production in West Africa is constraint by Striga gesnerioides parasitism associated with 83-100% yield loses which warrants development of resistance varieties against the parasite. An exotic resistant genotype, IT97K-499-35 developed by International Institute of Tropical Agriculture (IITA) was crossed with SARC-LO2, a local susceptible genotype. SSR-1 and C42-2B markers previously mapped in the region of S. gesnerioides resistance loci were used to amplify genomic DNA of advance recombinant inbred lines (RILs) of this cross. The responses of the RILS to Striga infection in pot culture and a field trial conformed to segregation ratio of resistance to susceptible genotypes of 1:1 among F 7 progenies suggesting monogenic dominant inheritance of the resistance. The markers SSR-1 and C42-2B mapped in the region of the resistance locus, but presented as dominant markers, with amplification only in resistant genotypes. The selective efficiency of SSR-1 (92.6%) was better than that of C42-2B (85.7%). In field trials, growth and morphology of susceptible genotypes were adversely affected by S. gesnerioides which resulted in significant (P ≤ 0.05) reduction in seed yield compared to resistant genotypes. The resistant RILs identified in the current work would be further evaluated in multi-location trials prior to their release to farmers for cultivation.
African Journal of Food, Agriculture, Nutrition and Development
Polyphenols are phytochemicals responsible for the astringency, bitterness, green flavours and an... more Polyphenols are phytochemicals responsible for the astringency, bitterness, green flavours and antioxidant activities in Theobroma cacao beans. Polyphenols degradation in cocoa beans during roasting is crucial to the flavour outcome and it is influenced by factors such as temperature, time and pod storage. Antioxidants are compounds that help to inhibit oxidation reactions caused by free radicals such as singlet oxygen, superoxide, peroxyl radicals, hydroxyl radicals and peroxynitrite thereby preventing damage to the cells and tissues. Their mechanisms of action include scavenging reactive oxygen and decreasing localised oxygen concentration thereby reducing molecular oxygen’s oxidation potential, metabolising lipid peroxides to n on-radical products and chelating metal ions to prevent generation of free radicals in humans. The study aimed at investigating changes in total polyphenols, anthocyanins, o -diphenols and antioxidant activity (free-radical scavenging activities) after roa...
African Journal of Food, Agriculture, Nutrition and Development, 2015
Fermentation and drying are critical to the development of flavour precursors that generate into ... more Fermentation and drying are critical to the development of flavour precursors that generate into distinctive chocolate flavour notes during industrial manufacture. These processes also lead to reduction in acidity and free fatty acids of nibs, which dictates the levels of bitterness and colour development in chocolates. This study investigated changes in nib acidity, flavour precursors (sugars concentration and proteins) and free fatty acids during drying of pulp pre-conditioned and fermented cocoa beans using a 4 x 3 full factorial experimental design with pod storage (0, 3, 7 and 10 days) and drying time (0, 3 and 6 days) as the principal factors. Non-volatile (titratable) acidity, pH, sugars (reducing, non-reducing and total sugars), changes in protein content and free fatty acids of the beans were studied using standard analytical methods. Increasing pod storage consistently increased pH of the fermented nibs at the end of drying with consequential decrease in titratable acidity...
African Journal of Biotechnology, 2014
Accurate identification of individual genotypes is important for cacao (Theobroma cacao L.) breed... more Accurate identification of individual genotypes is important for cacao (Theobroma cacao L.) breeding, germplasm conservation and seed propagation. The development of single nucleotide polymorphism (SNP) markers in cacao offers an effective way to use a high-throughput genotyping system for cacao genotype verification. In the present study, high-throughput genotyping with SNP markers was used to fingerprint 160 cacao trees in the germplasm collection at the Cocoa Research Institute of Ghana (CRIG). These accessions had been originally introduced from international germplasm collections. The multilocus SNP profiles, generated by the Sequenom Mass Spectrometry platform, were compared with the SNP profiles of reference trees maintained in the international cacao collections. The comparison unambiguously identified mislabeled trees. For materials introduced as hybrid seeds without an available reference genotype, parentage analysis and model-based assignment were applied to verify their recorded parentage and genetic background. Our study shows that a small set of polymorphic SNP markers can provide a robust and accurate result for cacao genotype identification. This protocol can be applied for large-scale genotyping of cacao as well as for many other crops.
In this investigation 45 parental cacao plants and five progeny derived from the parental stock s... more In this investigation 45 parental cacao plants and five progeny derived from the parental stock studied were genotyped using six SNP markers to determine off-types or mislabeled clones and to authenticate crosses made in the Cocoa Research Institute of Ghana (CRIG) breeding programme. Investigation was based on the 5' nuclease SNP assay using Illustra Hot Start mix Ready-To-Go PCR strips and BioTek FLx800TBP Fluorescence Microplate Reader. In a group of six cacao plants labeled as PA150 clones and another five labeled as Pound7, one clone in each group was unambiguously determined as off-type or mislabeled. Similarly, in a cohort of 23 PA7 "clones", four genotypes were differentiated. Cross-checking the fidelity of five progeny from the parental stock under study, it was established that no errors were made in the crossing. The most significant outcome of this study, however, was that out of the four categories of 23 PA7 candidate parental trees only one category can be comparable to the reference clone in the International Cacao Germplasm collection, Trinidad (ICG,T); thus informing the need for further work to find the correct clone among these for the breeding programme. It was thus concluded that this simple yet cutting-edge genotyping procedure can be used in applied cocoa breeding programmes in a cocoa producing country. This work represents a first step in the genotypic characterisation of the CRIG germplasm collection and Seed Gardens.
Archives of Biochemistry and Biophysics, 1993
Persia americana Mill (avocado) is a tree crop which originated from the tropics of the western h... more Persia americana Mill (avocado) is a tree crop which originated from the tropics of the western hemisphere and has developed varieties, adaptable to a wide range of climatic conditions. It has three general ecological varieties: Mexican, Guatemalan and West Indian. Its fruit is pear-shaped and the edible part is a thick layer of greenish-yellow pulp, high in protein and fat. The avocado plant is important for economic, nutritional and medicinal reasons. Studies have shown that its leaves could be used to manage high blood pressure. In Ghana, avocado is widely grown in the closed forest region, but it can be found in all regions. Despite the high nutritional content of avocado, malnutrition is prevalent in most rural communities in Ghana, and its potential medicinal use has not been fully investigated. Avocado has the potential to contribute immensely to the economy of Ghana if cultivated on commercial scale. We therefore investigated the distribution, uses, morphological and genetic...
Journal of Agricultural Science and Technology
Cocoa bean is an important raw material for the chocolate, pharmaceutical and cosmetic industries... more Cocoa bean is an important raw material for the chocolate, pharmaceutical and cosmetic industries. The butter content and other chemical components such as polyphenols play essential role in the health benefits of consumers as well as flavor of chocolates produced. In this study cocoa beans from 15 international clones (genotypes) were fermented and dried for six and 14 days, respectively. Genotypic effect on the major chemical components of the beans that affect chocolate flavour and taste were assessed using various protocols in the laboratory. Concentrations and relationship existing among the chemical components tested during three- and two-year periods were determined. Genotypic differences were found to account for variation in the concentration of various components tested. Among the genotypes used Man 15-2 seems to be high in fat content whilst IMC 47 was low. In terms of O-dihydric phenol content ICS 1 recorded the highest whilst MO 20 recorded the least. A further test on ...
Journal of Crop Improvement, 2013
ABSTRACT Clone development in cocoa is an essential step and a long-term goal in crop improvement... more ABSTRACT Clone development in cocoa is an essential step and a long-term goal in crop improvement programs. Selection theory suggests that ortet selection within high-yielding families will lead to development of productive clones. The present study aims to verify the relationship between clones and their progenitor ortets and source families for yield. Eight clones obtained from four families (two ortets per family) and five clones used as parents for these families were evaluated at two locations. Though a positive correlation for tree vigor was observed between the two locations, genotype × location interaction was indicated by rank changes for two of the 13 clones. A significant genetic correlation (rg = 0.76) was observed between vigor and yield. Ranking of ortets and of source families for yield was different from that of their descendant clones; ranking for vigor was, however, consistent between clones and progenitor ortets. Ortets that had high juvenile-stage vigor produced clones with the highest bean yields. Clones descended from the same family were similar in both vigor and yield, indicating that within-family genetic variances were low. The present results provided evidence that ortet selection for yield will be more effective in families where the progenitor clones combine good phenotypic value and favorable general combining ability for vigor and yield. Selecting within families based solely on the yield ranking of the families without considering these attributes of the progenitor clones will lead to less than expected genetic gains.
International Journal of Food Microbiology, 2013
The potential impact of aromatic and pectinolytic yeasts on cocoa flavour was investigated using ... more The potential impact of aromatic and pectinolytic yeasts on cocoa flavour was investigated using two defined mixed starter cultures encompassing strains of Pichia kluyveri and Kluyveromyces marxianus for inoculating cocoa beans in small scale tray fermentations. Samples for microbial and metabolite analysis were collected at 12-24 hour intervals during 120 h of fermentation. Yeast isolates were grouped by (GTG)5-based rep-PCR fingerprinting and identified by sequencing of the D1/D2 region of the 26S rRNA gene and the actin gene. Pulsed Field Gel Electrophoresis (PFGE) was conducted on isolates belonging to the species P. kluyveri and K. marxianus to verify strain level identity with the inoculated strains. Furthermore, Denaturing Gradient Gel Electrophoresis (DGGE) was performed to follow yeast and bacterial dynamics over time including the presence of the bacterial inoculum consisting of Lactobacillus fermentum and Acetobacter pasteurianus. Yeast cell counts peaked after 12 h of fermentation with the predominant species being identified as Hanseniaspora opuntiae and Hanseniaspora thailandica. P. kluyveri and K. marxianus were found to compose 9.3% and 13.5% of the yeast population, respectively, after 12 h of fermentation whilst PFGE showed that ~88% of all P. kluyveri isolates and 100% of all K. marxianus isolates were identical to the inoculated strains. Despite never being the dominant yeast species at any stage of fermentation, the un-conched chocolates produced from the two inoculated fermentations were judged by sensory analysis to differ in flavour profile compared to the spontaneously fermented control. This could indicate that yeasts have a greater impact on the sensory qualities of cocoa than previously assumed.
African Journal of Plant Science, 2018
Avocado (Persea americana Mill.) is an important economic tree crop grown in home gardens and far... more Avocado (Persea americana Mill.) is an important economic tree crop grown in home gardens and farms all over Ghana. Although there are some studies on diverse aspects of the crop in several parts of the world, not much has been documented about its morphology in Ghana. This study was therefore conducted to describe the morphology of avocado in the Ashanti and Central Regions of Ghana. Using the avocado descriptor as a guide, morphological analyses of P. americana accessions in eight districts in the two regions were conducted. The study revealed that the avocado accessions had variable morphological characteristics but were more close to the Western Indian accession.
Pod storage and fermentation are critical to the development of nib acidification and flavour pre... more Pod storage and fermentation are critical to the development of nib acidification and flavour precursors that generate into distinctive chocolate flavour notes during industrial manufacture. This work investigated changes in nib acidification, flavour precursors development (FPD) and free fatty acids (FFA) concentrations during drying of pulp pre-conditioned and fermented Ghanaian cocoa beans. A 4 x 4 full factorial design with experimental factors as pod storage (0, 7, 14 and 21 days) and drying times (0, 2, 4 and 6 days) were used. pH, non-volatile (titratable) acidity, total sugars, protein nitrogen and FFA concentrations were studied using standard methods. The results showed that pod storage and drying influenced the nib acidification, flavour precursors (protein nitrogen and total sugars) and FFA levels in fermented cocoa beans. Increasing pod storage consistently decreased non-volatile acidity, protein nitrogen and total sugars with concomitant increases in pH and FFAs during...
International Food Research Journal
Changes in acidification, sugars and mineral composition of cocoa pulp during fermentation of pul... more Changes in acidification, sugars and mineral composition of cocoa pulp during fermentation of pulp pre-conditioned cocoa (Theobroma cacao) beans were investigated using a 4 x 3 full factorial experimental design with pod storage and fermentation time as principal factors. pH, non-volatile (titratable) acidity, reducing sugars, total solids and mineral composition of cocoa pulp were studied using standard analytical methods. pH of the pulp increased with increasing pod storage and fermentation with consequential decrease in non-volatile acidity. Contrary, both pod storage and fermentation decreased the reducing sugars and total solids of the pulp. The most abundant mineral in unfermented cocoa pulp was calcium, followed by potassium and sodium with values of 316.92 mg/100 g, 255.12 mg/100 g and 103.26 mg/100 g respectively. Zinc was the mineral with the least concentration of 1.04 mg/100 g, whilst iron and magnesium had appreciable values of 4.26 mg/100 g and 32.52 mg/100 g respectiv...
Journal of the Ghana Science Association, 2003
Journal of the Ghana Science Association, 2004
Journal of the Ghana Science Association, Mar 1, 2000
Kola nuts wrapped with Mitragyna stipulosa (Akan: subaha) leaves and stored in baskets (tradition... more Kola nuts wrapped with Mitragyna stipulosa (Akan: subaha) leaves and stored in baskets (traditional method) and irradiated with Co-60 gamma rays with absorbed doses ranging from 0.10 to 0.50 kGy at a dose rate of 0.171 kGy/hr to control kola weevils (Balanogastris kolae) during storage. The number of nuts per treatment ranged between 20 and 1353, and the ambient storage temperature fluctuated between 16.5EC and 37.5E C. Gamma radiation suppressed the development and emergence of kola weevils that destroy the nuts in storage. Whilst no live insects were found in the treated samples, up to 48 live weevils were counted per packet in the control treatment at 28 days in storage. Consequently, nut infestation in the control was about 98.4%. Fungal deterioration of both irradiated and unirradiated kola nuts was observed. Weight loss in kola nuts irradiated at 0.25 and 0.50 kGy and stored for 84 days after irradiation was 18.2% and 19.2%, respectively, whilst comparable loss from the control treatment was 39.9%. Weevils fed with treated and untreated nuts did not show any preferences and differences in growth. A panel of tasters did not detect any differences between treated and untreated nuts. JOURNAL OF THE GHANA SCIENCE ASSOCIATION Volume 2 No. 3 (2000) pp. 184-192
European Scientific Journal, ESJ, Jul 12, 2013
Cowpea [Vigna unguiculata (L.) Walp.] production in West Africa is constraint by Striga gesnerioi... more Cowpea [Vigna unguiculata (L.) Walp.] production in West Africa is constraint by Striga gesnerioides parasitism associated with 83-100% yield loses which warrants development of resistance varieties against the parasite. An exotic resistant genotype, IT97K-499-35 developed by International Institute of Tropical Agriculture (IITA) was crossed with SARC-LO2, a local susceptible genotype. SSR-1 and C42-2B markers previously mapped in the region of S. gesnerioides resistance loci were used to amplify genomic DNA of advance recombinant inbred lines (RILs) of this cross. The responses of the RILS to Striga infection in pot culture and a field trial conformed to segregation ratio of resistance to susceptible genotypes of 1:1 among F 7 progenies suggesting monogenic dominant inheritance of the resistance. The markers SSR-1 and C42-2B mapped in the region of the resistance locus, but presented as dominant markers, with amplification only in resistant genotypes. The selective efficiency of SSR-1 (92.6%) was better than that of C42-2B (85.7%). In field trials, growth and morphology of susceptible genotypes were adversely affected by S. gesnerioides which resulted in significant (P ≤ 0.05) reduction in seed yield compared to resistant genotypes. The resistant RILs identified in the current work would be further evaluated in multi-location trials prior to their release to farmers for cultivation.
African Journal of Food, Agriculture, Nutrition and Development
Polyphenols are phytochemicals responsible for the astringency, bitterness, green flavours and an... more Polyphenols are phytochemicals responsible for the astringency, bitterness, green flavours and antioxidant activities in Theobroma cacao beans. Polyphenols degradation in cocoa beans during roasting is crucial to the flavour outcome and it is influenced by factors such as temperature, time and pod storage. Antioxidants are compounds that help to inhibit oxidation reactions caused by free radicals such as singlet oxygen, superoxide, peroxyl radicals, hydroxyl radicals and peroxynitrite thereby preventing damage to the cells and tissues. Their mechanisms of action include scavenging reactive oxygen and decreasing localised oxygen concentration thereby reducing molecular oxygen’s oxidation potential, metabolising lipid peroxides to n on-radical products and chelating metal ions to prevent generation of free radicals in humans. The study aimed at investigating changes in total polyphenols, anthocyanins, o -diphenols and antioxidant activity (free-radical scavenging activities) after roa...
African Journal of Food, Agriculture, Nutrition and Development, 2015
Fermentation and drying are critical to the development of flavour precursors that generate into ... more Fermentation and drying are critical to the development of flavour precursors that generate into distinctive chocolate flavour notes during industrial manufacture. These processes also lead to reduction in acidity and free fatty acids of nibs, which dictates the levels of bitterness and colour development in chocolates. This study investigated changes in nib acidity, flavour precursors (sugars concentration and proteins) and free fatty acids during drying of pulp pre-conditioned and fermented cocoa beans using a 4 x 3 full factorial experimental design with pod storage (0, 3, 7 and 10 days) and drying time (0, 3 and 6 days) as the principal factors. Non-volatile (titratable) acidity, pH, sugars (reducing, non-reducing and total sugars), changes in protein content and free fatty acids of the beans were studied using standard analytical methods. Increasing pod storage consistently increased pH of the fermented nibs at the end of drying with consequential decrease in titratable acidity...
African Journal of Biotechnology, 2014
Accurate identification of individual genotypes is important for cacao (Theobroma cacao L.) breed... more Accurate identification of individual genotypes is important for cacao (Theobroma cacao L.) breeding, germplasm conservation and seed propagation. The development of single nucleotide polymorphism (SNP) markers in cacao offers an effective way to use a high-throughput genotyping system for cacao genotype verification. In the present study, high-throughput genotyping with SNP markers was used to fingerprint 160 cacao trees in the germplasm collection at the Cocoa Research Institute of Ghana (CRIG). These accessions had been originally introduced from international germplasm collections. The multilocus SNP profiles, generated by the Sequenom Mass Spectrometry platform, were compared with the SNP profiles of reference trees maintained in the international cacao collections. The comparison unambiguously identified mislabeled trees. For materials introduced as hybrid seeds without an available reference genotype, parentage analysis and model-based assignment were applied to verify their recorded parentage and genetic background. Our study shows that a small set of polymorphic SNP markers can provide a robust and accurate result for cacao genotype identification. This protocol can be applied for large-scale genotyping of cacao as well as for many other crops.
In this investigation 45 parental cacao plants and five progeny derived from the parental stock s... more In this investigation 45 parental cacao plants and five progeny derived from the parental stock studied were genotyped using six SNP markers to determine off-types or mislabeled clones and to authenticate crosses made in the Cocoa Research Institute of Ghana (CRIG) breeding programme. Investigation was based on the 5' nuclease SNP assay using Illustra Hot Start mix Ready-To-Go PCR strips and BioTek FLx800TBP Fluorescence Microplate Reader. In a group of six cacao plants labeled as PA150 clones and another five labeled as Pound7, one clone in each group was unambiguously determined as off-type or mislabeled. Similarly, in a cohort of 23 PA7 "clones", four genotypes were differentiated. Cross-checking the fidelity of five progeny from the parental stock under study, it was established that no errors were made in the crossing. The most significant outcome of this study, however, was that out of the four categories of 23 PA7 candidate parental trees only one category can be comparable to the reference clone in the International Cacao Germplasm collection, Trinidad (ICG,T); thus informing the need for further work to find the correct clone among these for the breeding programme. It was thus concluded that this simple yet cutting-edge genotyping procedure can be used in applied cocoa breeding programmes in a cocoa producing country. This work represents a first step in the genotypic characterisation of the CRIG germplasm collection and Seed Gardens.
Archives of Biochemistry and Biophysics, 1993
Persia americana Mill (avocado) is a tree crop which originated from the tropics of the western h... more Persia americana Mill (avocado) is a tree crop which originated from the tropics of the western hemisphere and has developed varieties, adaptable to a wide range of climatic conditions. It has three general ecological varieties: Mexican, Guatemalan and West Indian. Its fruit is pear-shaped and the edible part is a thick layer of greenish-yellow pulp, high in protein and fat. The avocado plant is important for economic, nutritional and medicinal reasons. Studies have shown that its leaves could be used to manage high blood pressure. In Ghana, avocado is widely grown in the closed forest region, but it can be found in all regions. Despite the high nutritional content of avocado, malnutrition is prevalent in most rural communities in Ghana, and its potential medicinal use has not been fully investigated. Avocado has the potential to contribute immensely to the economy of Ghana if cultivated on commercial scale. We therefore investigated the distribution, uses, morphological and genetic...
Journal of Agricultural Science and Technology
Cocoa bean is an important raw material for the chocolate, pharmaceutical and cosmetic industries... more Cocoa bean is an important raw material for the chocolate, pharmaceutical and cosmetic industries. The butter content and other chemical components such as polyphenols play essential role in the health benefits of consumers as well as flavor of chocolates produced. In this study cocoa beans from 15 international clones (genotypes) were fermented and dried for six and 14 days, respectively. Genotypic effect on the major chemical components of the beans that affect chocolate flavour and taste were assessed using various protocols in the laboratory. Concentrations and relationship existing among the chemical components tested during three- and two-year periods were determined. Genotypic differences were found to account for variation in the concentration of various components tested. Among the genotypes used Man 15-2 seems to be high in fat content whilst IMC 47 was low. In terms of O-dihydric phenol content ICS 1 recorded the highest whilst MO 20 recorded the least. A further test on ...
Journal of Crop Improvement, 2013
ABSTRACT Clone development in cocoa is an essential step and a long-term goal in crop improvement... more ABSTRACT Clone development in cocoa is an essential step and a long-term goal in crop improvement programs. Selection theory suggests that ortet selection within high-yielding families will lead to development of productive clones. The present study aims to verify the relationship between clones and their progenitor ortets and source families for yield. Eight clones obtained from four families (two ortets per family) and five clones used as parents for these families were evaluated at two locations. Though a positive correlation for tree vigor was observed between the two locations, genotype × location interaction was indicated by rank changes for two of the 13 clones. A significant genetic correlation (rg = 0.76) was observed between vigor and yield. Ranking of ortets and of source families for yield was different from that of their descendant clones; ranking for vigor was, however, consistent between clones and progenitor ortets. Ortets that had high juvenile-stage vigor produced clones with the highest bean yields. Clones descended from the same family were similar in both vigor and yield, indicating that within-family genetic variances were low. The present results provided evidence that ortet selection for yield will be more effective in families where the progenitor clones combine good phenotypic value and favorable general combining ability for vigor and yield. Selecting within families based solely on the yield ranking of the families without considering these attributes of the progenitor clones will lead to less than expected genetic gains.
International Journal of Food Microbiology, 2013
The potential impact of aromatic and pectinolytic yeasts on cocoa flavour was investigated using ... more The potential impact of aromatic and pectinolytic yeasts on cocoa flavour was investigated using two defined mixed starter cultures encompassing strains of Pichia kluyveri and Kluyveromyces marxianus for inoculating cocoa beans in small scale tray fermentations. Samples for microbial and metabolite analysis were collected at 12-24 hour intervals during 120 h of fermentation. Yeast isolates were grouped by (GTG)5-based rep-PCR fingerprinting and identified by sequencing of the D1/D2 region of the 26S rRNA gene and the actin gene. Pulsed Field Gel Electrophoresis (PFGE) was conducted on isolates belonging to the species P. kluyveri and K. marxianus to verify strain level identity with the inoculated strains. Furthermore, Denaturing Gradient Gel Electrophoresis (DGGE) was performed to follow yeast and bacterial dynamics over time including the presence of the bacterial inoculum consisting of Lactobacillus fermentum and Acetobacter pasteurianus. Yeast cell counts peaked after 12 h of fermentation with the predominant species being identified as Hanseniaspora opuntiae and Hanseniaspora thailandica. P. kluyveri and K. marxianus were found to compose 9.3% and 13.5% of the yeast population, respectively, after 12 h of fermentation whilst PFGE showed that ~88% of all P. kluyveri isolates and 100% of all K. marxianus isolates were identical to the inoculated strains. Despite never being the dominant yeast species at any stage of fermentation, the un-conched chocolates produced from the two inoculated fermentations were judged by sensory analysis to differ in flavour profile compared to the spontaneously fermented control. This could indicate that yeasts have a greater impact on the sensory qualities of cocoa than previously assumed.
African Journal of Plant Science, 2018
Avocado (Persea americana Mill.) is an important economic tree crop grown in home gardens and far... more Avocado (Persea americana Mill.) is an important economic tree crop grown in home gardens and farms all over Ghana. Although there are some studies on diverse aspects of the crop in several parts of the world, not much has been documented about its morphology in Ghana. This study was therefore conducted to describe the morphology of avocado in the Ashanti and Central Regions of Ghana. Using the avocado descriptor as a guide, morphological analyses of P. americana accessions in eight districts in the two regions were conducted. The study revealed that the avocado accessions had variable morphological characteristics but were more close to the Western Indian accession.
Pod storage and fermentation are critical to the development of nib acidification and flavour pre... more Pod storage and fermentation are critical to the development of nib acidification and flavour precursors that generate into distinctive chocolate flavour notes during industrial manufacture. This work investigated changes in nib acidification, flavour precursors development (FPD) and free fatty acids (FFA) concentrations during drying of pulp pre-conditioned and fermented Ghanaian cocoa beans. A 4 x 4 full factorial design with experimental factors as pod storage (0, 7, 14 and 21 days) and drying times (0, 2, 4 and 6 days) were used. pH, non-volatile (titratable) acidity, total sugars, protein nitrogen and FFA concentrations were studied using standard methods. The results showed that pod storage and drying influenced the nib acidification, flavour precursors (protein nitrogen and total sugars) and FFA levels in fermented cocoa beans. Increasing pod storage consistently decreased non-volatile acidity, protein nitrogen and total sugars with concomitant increases in pH and FFAs during...
International Food Research Journal
Changes in acidification, sugars and mineral composition of cocoa pulp during fermentation of pul... more Changes in acidification, sugars and mineral composition of cocoa pulp during fermentation of pulp pre-conditioned cocoa (Theobroma cacao) beans were investigated using a 4 x 3 full factorial experimental design with pod storage and fermentation time as principal factors. pH, non-volatile (titratable) acidity, reducing sugars, total solids and mineral composition of cocoa pulp were studied using standard analytical methods. pH of the pulp increased with increasing pod storage and fermentation with consequential decrease in non-volatile acidity. Contrary, both pod storage and fermentation decreased the reducing sugars and total solids of the pulp. The most abundant mineral in unfermented cocoa pulp was calcium, followed by potassium and sodium with values of 316.92 mg/100 g, 255.12 mg/100 g and 103.26 mg/100 g respectively. Zinc was the mineral with the least concentration of 1.04 mg/100 g, whilst iron and magnesium had appreciable values of 4.26 mg/100 g and 32.52 mg/100 g respectiv...