Abraham Adu-Gyamfi | Graduate School of Nuclear and Allied Sciences (original) (raw)
Papers by Abraham Adu-Gyamfi
The effect of irradiation on the colour intensity of freeze-dried egg yolk samples (FDEY), from p... more The effect of irradiation on the colour intensity of freeze-dried egg yolk samples (FDEY), from poultry birds given feed containing different concentrations of annatto extract was investigated. Concentrations of 1, 4, 7 and 10 % of annatto extracts were used in the poultry feed formulation and these were compared with feed containing no additive as well as one containing a commercial feed colourant, 'carophyll yellow'. The FDEY samples coded R 1 , R 2 , R 3 , R 4 , C and C A respectively were inoculated with Salmonella parathyphi B and irradiated at doses of 0, 3 and 5 kGy with radiation from a 60 Co source. Microbial counts and colour intensity were determined after irradiation. Results of the microbiological analysis showed that both 3 and 5 kGy doses were adequate in practically eliminating Salmonella parathyphi B from the samples. However, it was observed from the colour analysis that irradiation at both 3 and 5 kGy doses caused significant (p < 0.0001) deterioration of the colour of the freeze-dried egg yolk samples.
The effect of irradiation on the colour intensity of freeze-dried egg yolk samples (FDEY), from p... more The effect of irradiation on the colour intensity of freeze-dried egg yolk samples (FDEY), from poultry birds given feed containing different concentrations of annatto extract was investigated. Concentrations of 1, 4, 7 and 10 % of annatto extracts were used in the poultry feed formulation and these were compared with feed containing no additive as well as one containing a commercial feed colourant, 'carophyll yellow'. The FDEY samples coded R 1 , R 2 , R 3 , R 4 , C and C A respectively were inoculated with Salmonella parathyphi B and irradiated at doses of 0, 3 and 5 kGy with radiation from a 60 Co source. Microbial counts and colour intensity were determined after irradiation. Results of the microbiological analysis showed that both 3 and 5 kGy doses were adequate in practically eliminating Salmonella parathyphi B from the samples. However, it was observed from the colour analysis that irradiation at both 3 and 5 kGy doses caused significant (p < 0.0001) deterioration ...
Chitosan extracted from sea crab shells was used to determine antifungal properties against Asper... more Chitosan extracted from sea crab shells was used to determine antifungal properties against Aspergillus niger. Chitosan powder irradiated at 100 kGy and dissolved in 1 % acetic acid (v/v) with pH adjusted to approximately 6.0 was used in preparing chitosan concentrations of 2 %, 1.5 %, 1 % and 0.5 %. The agar dilution method was used to test the antifungal activity of the various chitosan solutions at concentrations of 0.20 %, 0.15 %, 0.10 % and 0.05 %. Both media containing irradiated and unirradiated chitosan inhibited the mycelial growth of Aspergillus niger and the degree of inhibition was dependent on the concentration of the chitosan in the fungal growth medium. Results show that the media containing irradiated chitosan inhibited the mycelia growth of Aspergillus niger to a greater extent than the media containing unirradiated chitosan.
International Journal of Nutrition and Food Sciences, 2014
International Journal of Nutrition and Food Sciences, 2014
Radiation processing is an extremely flexible, versatile and cost-effective technology with immen... more Radiation processing is an extremely flexible, versatile and cost-effective technology with immense applications in the areas of postharvest management of agricultural produce, medical sterilisation, industrial materials modification and environmental management. Since 1970, Ghana Atomic Energy Commission has been undertaking research and development activities in radiation processing with the use of a laboratory scale irradiator. In 1994, a pilot-scale Cobalt-60 irradiator was acquired for the Radiation Technology Centre (RTC) through the assistance of the International Atomic Energy Agency and the government of Ghana for techno-economic feasibility studies and limited commercial operations. Due to the reduction in activity of the Cobalt-60 source of the irradiator over the years and other inherent design limitations, efficiency of operations have significantly reduced. Several efforts have been made to secure funding for upgrading and expanding the facility. Although limited fundi...
Microorganisms attach to surfaces and develop biofilms which have been implicated in a variety of... more Microorganisms attach to surfaces and develop biofilms which have been implicated in a variety of human diseases with great importance for public health .Unfortunately, biofilm-associated diseases are resistant to conventional biocides and host immune systems. As a result there is a rise in difficult-to-treat human infections with an increase in cost to the health sector. The objective of this study was to review literature on biofilm-associated microbes with respect to factors controlling biofilm formation, life cycle, structure and composition, detachment and dispersal, resistance to antimicrobials and host immune systems, their contribution to the disease burden of man and public health implications of biofilm-associated diseases. A greater understanding of biofilm processes will help provide the basis for the development of guidelines for biofilm-related biosafety and public health risk assessment as well as development of novel and effective control strategies.
Antimicrobial resistance is said to currently be the greatest challenge to the effective treatmen... more Antimicrobial resistance is said to currently be the greatest challenge to the effective treatment of infections globally. This study evaluated the risks of antimicrobial resistant microbes associated with 8 types of branded and unbranded milk sold in Accra, Ghana. The study revealed that 6 categories of milk sampled were all contaminated whiles 2 categories were not. Common isolates identified were E.coli, Klebsiella spp , Enterobacter spp, Proteus vulgaris, Salmonella tyhpi, Enterococcus faecalis, Staphylococccus aureus and Staphylococcus epidermidis. Antibiotic susceptibility tests indicated that all (100%) isolates were multi-resistant to Ampicillin, Tetracycline, Chloramphenicol, Gentamycin, Cotrimoxazole, Ceturoxime and cefotaxime. Ceftriaxime was the most effective antimicrobial but even then, 90.57% of isolates were resistant to it. Antimicrobial resistant isolates were found in all types of milk sampled. Unpasteurized locally produced cow milk accounted for the highest (26....
Ghana Journal of Agricultural Science, 2007
... REFERENCES Adu-Gyamfi, A. (2000) Microbiological analysis of spices and dried seasonings. ...... more ... REFERENCES Adu-Gyamfi, A. (2000) Microbiological analysis of spices and dried seasonings. ... Proceedings of FAO/IAEA/WHO International Conference on Ensuring the Safety and Quality of Food through Radiation Processing (ed. P. Loaharanu and P. Thomas). ...
British Journal of Applied Science & Technology, 2015
To develop a nutritious product from banana for infants and increase banana utilization. Methodol... more To develop a nutritious product from banana for infants and increase banana utilization. Methodology: Banana samples obtained from the Volta River Estate Limited were solar dried and milled into flour. Soybean and maize were obtained from a local market in Madina, Accra, mechanically dried and made into flour. Banana, soy bean and maize flour were mixed into composite flour in seven different percentage ratios. Physicochemical and elemental analyses were performed on the seven different banana composite flours. Results: Results showed a significant difference in all parameters analysed for all the seven different banana compositions. Composite flour made of local crops, banana, soybean and maize, had high levels of potassium and sodium (19350 mg/kg and 12850 mg/kg respectively) and appreciable levels of Iron, Zinc and manganese. Physicochemical analyses showed total
Fourteen international ready meals prepared under the approved hazard analysis critical control p... more Fourteen international ready meals prepared under the approved hazard analysis critical control point (HACCP) plan and two Ghanaian ready meals, waakye (co-boiled rice and cowpeas served with gravy, minimally processed vegetable salad, hydrated gari, fried fish and macaroni) and jollof rice (rice cooked in tomato sauce and served with gravy and beef tripe), were investigated with the view to enhancing microbiological safety and extending shelf life under chilled conditions. The microbiological count of the complete waakye meal exceeded the microbiological standard. The microbiological counts on meals prepared under the HACCP plan and the jollof rice meals were within the microbiological standards. The D10 values for potential pathogens on waakye were 0.271 kGy for Escherichia coli, 0.325 kGy for Salmonella aureus and 0.440 kGy for Salmonella spp. while the D10 values on jollof rice meal were 0.173 kGy, 0.260 kGy and 0.285 kGy, respectively. Challenge tests with the pathogens on one ...
Studies have confirmed radiation processing as an effective technology capable of improving the s... more Studies have confirmed radiation processing as an effective technology capable of improving the safety and quality of many foods and the hygienic quality of medical products. Against the backdrop of few successful commercialisation of technological innovations in Africa, the paper looks at efforts to upgrade the Gamma Irradiation Facility (GIF) at the Ghana Atomic Energy Commission for better management of post harvest losses and improvement in the quality of agricultural exports as well as sterilisation of medical products in Ghana. From a starting point of initial laboratory scale research to a later period of semi-commercial utilisation to meet the needs of both the public and private sector, there is now the need to up-scale to a commercial level and this requires capital injection for which presently some funding has been secured. The present study discusses the business opportunity this technology offers to potential investors and appendages to local businesses when operationa...
African journal of microbiology research
This study evaluated the effect of frequently used veterinary wound antimicrobials for their effi... more This study evaluated the effect of frequently used veterinary wound antimicrobials for their efficacy in killing mature in vitro Staphylococcus aureus biofilms and inhibiting planktonic cells. The predictiveness of the minimum biofilm eradication concentration (MBEC) assay as a tool for antibiotic susceptibility testing was also assessed. The minimum inhibitory concentration (MIC) and MBEC of tetracycline, tetracycline-based commercial wound spray, silver nitrate, gentian violet, iodine tincture, sucrose and a laboratory mixture of sucrose and gentian violet were determined. Whereas low concentrations of all these antimicrobials except sucrose inhibited planktonic S. aureus, only silver nitrate eradicated the biofilm phenotype. Silver nitrate at a Ag+ concentration of 4 x MIC showed 100% efficiency of removal or 7.70-log reduction of S. aureus biofilm cells, 1% gentian violet gave a significant reduction (55% or 0.35-log, P = 0.046) and 120% sucrose in gentian violet also showed a s...
Chitosan extracted from sea crab shells was used to determine antifungal properties against Asper... more Chitosan extracted from sea crab shells was used to determine antifungal properties against Aspergillus niger. Chitosan powder irradiated at 100 kGy and dissolved in 1 % acetic acid (v/v) with pH adjusted to approximately 6.0 was used in preparing chitosan concentrations of 2 %, 1.5 %, 1 % and 0.5 %. The agar dilution method was used to test the antifungal activity of the various chitosan solutions at concentrations of 0.20 %, 0.15 %, 0.10 % and 0.05 %. Both media containing irradiated and unirradiated chitosan inhibited the mycelial growth of Aspergillus niger and the degree of inhibition was dependent on the concentration of the chitosan in the fungal growth medium. Results show that the media containing irradiated chitosan inhibited the mycelia growth of Aspergillus niger to a greater extent than the media containing unirradiated chitosan.
Journal of medicinal plant research
Seven dried herbal products (DHP) were decontaminated using gamma radiation. The microbial loads ... more Seven dried herbal products (DHP) were decontaminated using gamma radiation. The microbial loads (total viable count, TVC) of the raw and irradiated products were determined using the methods of serial dilutions and pour plate. Based on international standards for microbial load, the effective decontamination doses were determined for the DHP. The range of TVC for the DHP was 10 5 to 10 9 cfu/g. Milled roots of Cryptolepis sanguinolenta and milled stems and leaves of Desmodium adscendens had the highest counts of 8.0 × 10 8 and 2.0 × 10 9 cfu/g, respectively. Powdered seeds of Moringa olifera and Grifornia simplicifolia and the seeds of Voacanga africanus had relatively low TVCs of 6.4 × 10 5 , 6.6 × 10 6 and 1.3 × 10 6 cfu/g, respectively. Irradiation with medium doses of 2.5 to 7.5 kGy reduced microbial loads of the DHP by 3 to 6 log cycles. A dose of 10 kGy reduced the microbial load by 4 to7 log cycles and a dose of 15 kGy eliminated viable cells from all the DHP. Effective deco...
Combined effect of irradiation and frozen storage on viable bacteria and inoculated Eschericia co... more Combined effect of irradiation and frozen storage on viable bacteria and inoculated Eschericia coli in chicken was investigated. Samples of uninoculated chicken and samples of chicken inoculated with E. coli were irradiated using a Co-60 source at doses of 0, 2 ,4,6 and 8 kGy and stored for 0, 7, 14, 21, 28, 35, 42, 49 and 56 days at -18 0 C. Samples were analyzed each week to enumerate surviving viable bacteria and E. coli. Irradiation doses of 2, 4, 6, and 8 kGy respectively reduced the population of viable bacteria in the uninoculated chicken by 2.06, 2.96, 3.91 and 4.21 log cycles. Storage for 56 days reduced populations of viable bacteria by approximately 2 log cycles for all irradiated uninoculated samples. Dose of 2 kGy reduced the population of E. coli in the unirradiated sample by 2.69 log cycles and 4, 6, 8 kGy reduced the population by > 7 log cycles. Storage for 56 days reduced the population of E. coli by 4.07 and > 3.52 log cycles respectively in the unirradiated...
Fresh-cut mangoes are nutritious and offer consumers freshness, flavour and convenience. They how... more Fresh-cut mangoes are nutritious and offer consumers freshness, flavour and convenience. They however have a shorter shelf life compared to whole fruits due to their high susceptibility to microbial contamination. The effects of gamma irradiation and chemical preservatives on the microbiological quality of refrigerated fresh-cut mangoes were evaluated. Well matured fruits of Kent and Keitt varieties sliced into cubes were microbiologically analysed initially to determine counts of total viable cells (TVC), coliforms, Salmonella sp., Staphylococcus aureus and Escherichia coli. The samples were subjected to various irradiation doses (0, 1.0, 1.5, 2.0 and 2.5 kGy) and chemical preservatives (sucrose, citric acid, sodium benzoate and a combination of these chemicals in equal proportions) and stored at 6°C and 10ºC for 15 days. TVC was subsequently estimated at 3-day intervals for the treated samples. TVC was estimated as 3.53 ± 0.25 and 4.86 ± 0.38 log 10 cfu/g for the Kent and Keitt varieties respectively. No coliforms Salmonella sp., E. coli or S. aureus were detected in both varieties. Irradiation at doses of 1.5 kGy to 2.5 kGy in combination with storage at 6ºC was able to eliminate
Due to the mode of processing, storage and marketing, the quality of dried food ingredients can e... more Due to the mode of processing, storage and marketing, the quality of dried food ingredients can easily be compromised. This study was conducted to assess the quality of fish powder and shrimp powder sold on the market.Twenty (20) Dried Food Ingredients (DFI) consisting of ten fish powder and ten shrimp powder from two local markets (Madina and Dome) were analysed for moisture, total ash, pHand total free fatty acids according to approved methods of Association of Analytical Chemists (AOAC). Microbial load determination was also carried out on samples using serial dilution and pour plate techniques. Analysis ofmicronutrients and heavy metal, were carried out using Atomic Absorption Spectroscopy and Nuclear Activation Analysis respectively.Moisture, dry matter and ph of Shrimp powder (SP)from Dome market were significantly higher (p<0.05) than that from Madina market.pH for Fish powder (FP) ranged from 5.71 to 7.62 which differed significantly for both markets.The highest moisture ...
The effect of irradiation on the colour intensity of freeze-dried egg yolk samples (FDEY), from p... more The effect of irradiation on the colour intensity of freeze-dried egg yolk samples (FDEY), from poultry birds given feed containing different concentrations of annatto extract was investigated. Concentrations of 1, 4, 7 and 10 % of annatto extracts were used in the poultry feed formulation and these were compared with feed containing no additive as well as one containing a commercial feed colourant, 'carophyll yellow'. The FDEY samples coded R 1 , R 2 , R 3 , R 4 , C and C A respectively were inoculated with Salmonella parathyphi B and irradiated at doses of 0, 3 and 5 kGy with radiation from a 60 Co source. Microbial counts and colour intensity were determined after irradiation. Results of the microbiological analysis showed that both 3 and 5 kGy doses were adequate in practically eliminating Salmonella parathyphi B from the samples. However, it was observed from the colour analysis that irradiation at both 3 and 5 kGy doses caused significant (p < 0.0001) deterioration of the colour of the freeze-dried egg yolk samples.
The effect of irradiation on the colour intensity of freeze-dried egg yolk samples (FDEY), from p... more The effect of irradiation on the colour intensity of freeze-dried egg yolk samples (FDEY), from poultry birds given feed containing different concentrations of annatto extract was investigated. Concentrations of 1, 4, 7 and 10 % of annatto extracts were used in the poultry feed formulation and these were compared with feed containing no additive as well as one containing a commercial feed colourant, 'carophyll yellow'. The FDEY samples coded R 1 , R 2 , R 3 , R 4 , C and C A respectively were inoculated with Salmonella parathyphi B and irradiated at doses of 0, 3 and 5 kGy with radiation from a 60 Co source. Microbial counts and colour intensity were determined after irradiation. Results of the microbiological analysis showed that both 3 and 5 kGy doses were adequate in practically eliminating Salmonella parathyphi B from the samples. However, it was observed from the colour analysis that irradiation at both 3 and 5 kGy doses caused significant (p < 0.0001) deterioration ...
Chitosan extracted from sea crab shells was used to determine antifungal properties against Asper... more Chitosan extracted from sea crab shells was used to determine antifungal properties against Aspergillus niger. Chitosan powder irradiated at 100 kGy and dissolved in 1 % acetic acid (v/v) with pH adjusted to approximately 6.0 was used in preparing chitosan concentrations of 2 %, 1.5 %, 1 % and 0.5 %. The agar dilution method was used to test the antifungal activity of the various chitosan solutions at concentrations of 0.20 %, 0.15 %, 0.10 % and 0.05 %. Both media containing irradiated and unirradiated chitosan inhibited the mycelial growth of Aspergillus niger and the degree of inhibition was dependent on the concentration of the chitosan in the fungal growth medium. Results show that the media containing irradiated chitosan inhibited the mycelia growth of Aspergillus niger to a greater extent than the media containing unirradiated chitosan.
International Journal of Nutrition and Food Sciences, 2014
International Journal of Nutrition and Food Sciences, 2014
Radiation processing is an extremely flexible, versatile and cost-effective technology with immen... more Radiation processing is an extremely flexible, versatile and cost-effective technology with immense applications in the areas of postharvest management of agricultural produce, medical sterilisation, industrial materials modification and environmental management. Since 1970, Ghana Atomic Energy Commission has been undertaking research and development activities in radiation processing with the use of a laboratory scale irradiator. In 1994, a pilot-scale Cobalt-60 irradiator was acquired for the Radiation Technology Centre (RTC) through the assistance of the International Atomic Energy Agency and the government of Ghana for techno-economic feasibility studies and limited commercial operations. Due to the reduction in activity of the Cobalt-60 source of the irradiator over the years and other inherent design limitations, efficiency of operations have significantly reduced. Several efforts have been made to secure funding for upgrading and expanding the facility. Although limited fundi...
Microorganisms attach to surfaces and develop biofilms which have been implicated in a variety of... more Microorganisms attach to surfaces and develop biofilms which have been implicated in a variety of human diseases with great importance for public health .Unfortunately, biofilm-associated diseases are resistant to conventional biocides and host immune systems. As a result there is a rise in difficult-to-treat human infections with an increase in cost to the health sector. The objective of this study was to review literature on biofilm-associated microbes with respect to factors controlling biofilm formation, life cycle, structure and composition, detachment and dispersal, resistance to antimicrobials and host immune systems, their contribution to the disease burden of man and public health implications of biofilm-associated diseases. A greater understanding of biofilm processes will help provide the basis for the development of guidelines for biofilm-related biosafety and public health risk assessment as well as development of novel and effective control strategies.
Antimicrobial resistance is said to currently be the greatest challenge to the effective treatmen... more Antimicrobial resistance is said to currently be the greatest challenge to the effective treatment of infections globally. This study evaluated the risks of antimicrobial resistant microbes associated with 8 types of branded and unbranded milk sold in Accra, Ghana. The study revealed that 6 categories of milk sampled were all contaminated whiles 2 categories were not. Common isolates identified were E.coli, Klebsiella spp , Enterobacter spp, Proteus vulgaris, Salmonella tyhpi, Enterococcus faecalis, Staphylococccus aureus and Staphylococcus epidermidis. Antibiotic susceptibility tests indicated that all (100%) isolates were multi-resistant to Ampicillin, Tetracycline, Chloramphenicol, Gentamycin, Cotrimoxazole, Ceturoxime and cefotaxime. Ceftriaxime was the most effective antimicrobial but even then, 90.57% of isolates were resistant to it. Antimicrobial resistant isolates were found in all types of milk sampled. Unpasteurized locally produced cow milk accounted for the highest (26....
Ghana Journal of Agricultural Science, 2007
... REFERENCES Adu-Gyamfi, A. (2000) Microbiological analysis of spices and dried seasonings. ...... more ... REFERENCES Adu-Gyamfi, A. (2000) Microbiological analysis of spices and dried seasonings. ... Proceedings of FAO/IAEA/WHO International Conference on Ensuring the Safety and Quality of Food through Radiation Processing (ed. P. Loaharanu and P. Thomas). ...
British Journal of Applied Science & Technology, 2015
To develop a nutritious product from banana for infants and increase banana utilization. Methodol... more To develop a nutritious product from banana for infants and increase banana utilization. Methodology: Banana samples obtained from the Volta River Estate Limited were solar dried and milled into flour. Soybean and maize were obtained from a local market in Madina, Accra, mechanically dried and made into flour. Banana, soy bean and maize flour were mixed into composite flour in seven different percentage ratios. Physicochemical and elemental analyses were performed on the seven different banana composite flours. Results: Results showed a significant difference in all parameters analysed for all the seven different banana compositions. Composite flour made of local crops, banana, soybean and maize, had high levels of potassium and sodium (19350 mg/kg and 12850 mg/kg respectively) and appreciable levels of Iron, Zinc and manganese. Physicochemical analyses showed total
Fourteen international ready meals prepared under the approved hazard analysis critical control p... more Fourteen international ready meals prepared under the approved hazard analysis critical control point (HACCP) plan and two Ghanaian ready meals, waakye (co-boiled rice and cowpeas served with gravy, minimally processed vegetable salad, hydrated gari, fried fish and macaroni) and jollof rice (rice cooked in tomato sauce and served with gravy and beef tripe), were investigated with the view to enhancing microbiological safety and extending shelf life under chilled conditions. The microbiological count of the complete waakye meal exceeded the microbiological standard. The microbiological counts on meals prepared under the HACCP plan and the jollof rice meals were within the microbiological standards. The D10 values for potential pathogens on waakye were 0.271 kGy for Escherichia coli, 0.325 kGy for Salmonella aureus and 0.440 kGy for Salmonella spp. while the D10 values on jollof rice meal were 0.173 kGy, 0.260 kGy and 0.285 kGy, respectively. Challenge tests with the pathogens on one ...
Studies have confirmed radiation processing as an effective technology capable of improving the s... more Studies have confirmed radiation processing as an effective technology capable of improving the safety and quality of many foods and the hygienic quality of medical products. Against the backdrop of few successful commercialisation of technological innovations in Africa, the paper looks at efforts to upgrade the Gamma Irradiation Facility (GIF) at the Ghana Atomic Energy Commission for better management of post harvest losses and improvement in the quality of agricultural exports as well as sterilisation of medical products in Ghana. From a starting point of initial laboratory scale research to a later period of semi-commercial utilisation to meet the needs of both the public and private sector, there is now the need to up-scale to a commercial level and this requires capital injection for which presently some funding has been secured. The present study discusses the business opportunity this technology offers to potential investors and appendages to local businesses when operationa...
African journal of microbiology research
This study evaluated the effect of frequently used veterinary wound antimicrobials for their effi... more This study evaluated the effect of frequently used veterinary wound antimicrobials for their efficacy in killing mature in vitro Staphylococcus aureus biofilms and inhibiting planktonic cells. The predictiveness of the minimum biofilm eradication concentration (MBEC) assay as a tool for antibiotic susceptibility testing was also assessed. The minimum inhibitory concentration (MIC) and MBEC of tetracycline, tetracycline-based commercial wound spray, silver nitrate, gentian violet, iodine tincture, sucrose and a laboratory mixture of sucrose and gentian violet were determined. Whereas low concentrations of all these antimicrobials except sucrose inhibited planktonic S. aureus, only silver nitrate eradicated the biofilm phenotype. Silver nitrate at a Ag+ concentration of 4 x MIC showed 100% efficiency of removal or 7.70-log reduction of S. aureus biofilm cells, 1% gentian violet gave a significant reduction (55% or 0.35-log, P = 0.046) and 120% sucrose in gentian violet also showed a s...
Chitosan extracted from sea crab shells was used to determine antifungal properties against Asper... more Chitosan extracted from sea crab shells was used to determine antifungal properties against Aspergillus niger. Chitosan powder irradiated at 100 kGy and dissolved in 1 % acetic acid (v/v) with pH adjusted to approximately 6.0 was used in preparing chitosan concentrations of 2 %, 1.5 %, 1 % and 0.5 %. The agar dilution method was used to test the antifungal activity of the various chitosan solutions at concentrations of 0.20 %, 0.15 %, 0.10 % and 0.05 %. Both media containing irradiated and unirradiated chitosan inhibited the mycelial growth of Aspergillus niger and the degree of inhibition was dependent on the concentration of the chitosan in the fungal growth medium. Results show that the media containing irradiated chitosan inhibited the mycelia growth of Aspergillus niger to a greater extent than the media containing unirradiated chitosan.
Journal of medicinal plant research
Seven dried herbal products (DHP) were decontaminated using gamma radiation. The microbial loads ... more Seven dried herbal products (DHP) were decontaminated using gamma radiation. The microbial loads (total viable count, TVC) of the raw and irradiated products were determined using the methods of serial dilutions and pour plate. Based on international standards for microbial load, the effective decontamination doses were determined for the DHP. The range of TVC for the DHP was 10 5 to 10 9 cfu/g. Milled roots of Cryptolepis sanguinolenta and milled stems and leaves of Desmodium adscendens had the highest counts of 8.0 × 10 8 and 2.0 × 10 9 cfu/g, respectively. Powdered seeds of Moringa olifera and Grifornia simplicifolia and the seeds of Voacanga africanus had relatively low TVCs of 6.4 × 10 5 , 6.6 × 10 6 and 1.3 × 10 6 cfu/g, respectively. Irradiation with medium doses of 2.5 to 7.5 kGy reduced microbial loads of the DHP by 3 to 6 log cycles. A dose of 10 kGy reduced the microbial load by 4 to7 log cycles and a dose of 15 kGy eliminated viable cells from all the DHP. Effective deco...
Combined effect of irradiation and frozen storage on viable bacteria and inoculated Eschericia co... more Combined effect of irradiation and frozen storage on viable bacteria and inoculated Eschericia coli in chicken was investigated. Samples of uninoculated chicken and samples of chicken inoculated with E. coli were irradiated using a Co-60 source at doses of 0, 2 ,4,6 and 8 kGy and stored for 0, 7, 14, 21, 28, 35, 42, 49 and 56 days at -18 0 C. Samples were analyzed each week to enumerate surviving viable bacteria and E. coli. Irradiation doses of 2, 4, 6, and 8 kGy respectively reduced the population of viable bacteria in the uninoculated chicken by 2.06, 2.96, 3.91 and 4.21 log cycles. Storage for 56 days reduced populations of viable bacteria by approximately 2 log cycles for all irradiated uninoculated samples. Dose of 2 kGy reduced the population of E. coli in the unirradiated sample by 2.69 log cycles and 4, 6, 8 kGy reduced the population by > 7 log cycles. Storage for 56 days reduced the population of E. coli by 4.07 and > 3.52 log cycles respectively in the unirradiated...
Fresh-cut mangoes are nutritious and offer consumers freshness, flavour and convenience. They how... more Fresh-cut mangoes are nutritious and offer consumers freshness, flavour and convenience. They however have a shorter shelf life compared to whole fruits due to their high susceptibility to microbial contamination. The effects of gamma irradiation and chemical preservatives on the microbiological quality of refrigerated fresh-cut mangoes were evaluated. Well matured fruits of Kent and Keitt varieties sliced into cubes were microbiologically analysed initially to determine counts of total viable cells (TVC), coliforms, Salmonella sp., Staphylococcus aureus and Escherichia coli. The samples were subjected to various irradiation doses (0, 1.0, 1.5, 2.0 and 2.5 kGy) and chemical preservatives (sucrose, citric acid, sodium benzoate and a combination of these chemicals in equal proportions) and stored at 6°C and 10ºC for 15 days. TVC was subsequently estimated at 3-day intervals for the treated samples. TVC was estimated as 3.53 ± 0.25 and 4.86 ± 0.38 log 10 cfu/g for the Kent and Keitt varieties respectively. No coliforms Salmonella sp., E. coli or S. aureus were detected in both varieties. Irradiation at doses of 1.5 kGy to 2.5 kGy in combination with storage at 6ºC was able to eliminate
Due to the mode of processing, storage and marketing, the quality of dried food ingredients can e... more Due to the mode of processing, storage and marketing, the quality of dried food ingredients can easily be compromised. This study was conducted to assess the quality of fish powder and shrimp powder sold on the market.Twenty (20) Dried Food Ingredients (DFI) consisting of ten fish powder and ten shrimp powder from two local markets (Madina and Dome) were analysed for moisture, total ash, pHand total free fatty acids according to approved methods of Association of Analytical Chemists (AOAC). Microbial load determination was also carried out on samples using serial dilution and pour plate techniques. Analysis ofmicronutrients and heavy metal, were carried out using Atomic Absorption Spectroscopy and Nuclear Activation Analysis respectively.Moisture, dry matter and ph of Shrimp powder (SP)from Dome market were significantly higher (p<0.05) than that from Madina market.pH for Fish powder (FP) ranged from 5.71 to 7.62 which differed significantly for both markets.The highest moisture ...