George Tawia Odamtten

Chemical constituents and antimicrobial activity of medicinal plants from Ghana: Cassia sieberiana, Haematostaphis barteri, Mitragyna inermis and Pseudocedrela kotschyi

The antimicrobial activity of the sequential n‐hexane, acetone and 50% aqueous methanol extracts of leaves, stem bark and roots of four species of medicinal plants, Cassia sieberiana DC. (Leguminosae), Haematostaphis barteri Hook. f. (Anacardiaceae), Mitragyna inermis (Willd.) O. Kuntze (Rubiaceae) and Pseudocedrela kotschyi (Schweinf.) Harms (Meliaceae), from Ghana were tested against Bacillus subtilis, Pseudomonas syringae and Cladosporium herbarum using TLC direct‐autobiographic methods. Extracts from leaves, stem bark and roots of the four species gave a positive result against at least one test organism. Twelve of the 36 extracts were active against B. subtilis, four extracts were active against P. syringae and six were active against C. herbarum. Preliminary chemical analysis revealed the presence of flavonoids, stilbenes and alkaloids. This is the first report of a stilbene from the Anacardiaceae. Copyright

Evaluating the Effect of Gamma Radiation on the Total Phenolic Content, Flavonoids, and Antioxidant Activity of Dried Pleurotus ostreatus ((Jacq. ex. Fr) Kummer) Stored in Packaging Materials

Dried Pleurotus ostreatus mushrooms stored in polythene and polypropylene packs were exposed to gamma radiation from a cobalt-60 source at doses of 0, 0.5, 1, 1.5, and 2 kGy at a dose rate of 1.7 kGy/hr and stored for a period of 1 month. Total phenolic contents, flavonoids, and free radical scavenging activity DPPH (2,2′-diphenyl-1-picrylhydrazyl) were determined using aqueous, ethanol, and methanol extracts by Folin-Ciocaultaeu method as a source of potential natural antioxidants. Total phenol content ranged 0.56 ± 0.01–10.96 ± 1.7 mg/GAE, flavonoids ranged 1.64 ± 0.05–8.92 ± 0.6 mg/QE, DPPH radical scavenging activity also ranged 7.02 ± 0.10–13.03 ± 0.04%, and IC50 values also ranged 0.08–0.16 mg/mL. Statistical differences (P < 0.05) were recorded for the extracts and the treatment doses of mushrooms stored in polythene and polypropylene packs. A significant linear correlation was confirmed between values for the total phenolic content and antioxidant activity of mushroom extracts. The high contents of phenolic compounds indicated that these compounds contribute to high antioxidant activity. Pleurotus ostreatus can be regarded as a promising candidate for natural mushroom sources of antioxidants with high value. The use of low dose gamma radiation by the local food industry could improve the hygienic quality, extend shelf-life, and preserve nutrients and antinutrients.

Identification and molecular characterisation of Colletotrichum species from avocado, citrus and pawpaw in Ghana

Owing to previous identifications based solely on morphological characteristics, the identity of the causal agents of anthracnose disease of pawpaw and avocado in Ghana is in doubt. In addition, the pathogen has not been identified previously on citrus. In this study, isolates of the pathogen were obtained from anthracnose lesions on avocado and pawpaw, and atypical anthracnose lesions on citrus. The isolates were identified using PCR with species-specific primers, complemented by phylogenetic analysis of nucleotide sequences of the internal transcribed spacer region and partial glyceraldehyde-3-phosphate dehydrogenase gene. The pathogenicity of the isolated fungi was determined on detached matured fruits. All isolates, including those isolated from citrus, were identified as Colletotrichum gloeosporioides from the expected 480 bp PCR products amplified by PCR. The phylogenetic analysis showed that isolates from avocado and pawpaw were C. siamense, rather than C. gloeosporioides, whereas isolates from citrus were C. gloeosporioides sensu stricto. The pathogens were able to induce disease only on wounded mature fruits.

Mycofloral profile and the radiation sensitivity (D10 values) of solar dried and gamma irradiated Pleurotus ostreatus (Jacq.Ex. Fr.) Kummer fruitbodies stored in two different packaging materials

Abstract The presence of fungi in our foods poses serious health risks as some genera of fungi may produce certain mycotoxins which have carcinogenic, mutagenic, teratogenic, and immunosuppressive effect on humans and animals alike. Fruitbodies of Pleurotus ostreatus were solar dried at a moisture content of 12.5 ± 0.2% and stored in polythene and polypropylene packs, gamma irradiated at doses of 0 (control), 1, 2, 3, 4, and 5 kGy at a dose rate of 1.7 kGy/hr from a Cobalt 60 source (SLL, 515, Hungary) and stored at room temperature 28–30°C for a period of 12 months. Mycological analyses were done at intervals of 0, 3, 6, and 12 months. A total of eleven (11) fungi belonging to eight fungal genera were isolated on both Cookes and DRBC media; Aspergillus (A. niger, A. flavus, A. fumigatus, A. tamarii), Rhizopus (R. oligosporus), Mucor (M. racemosus), Fusarium (F. oxysporum), Penicillium (Penicillium sp.), Trichoderma (T. viride), and Rhodotorula sp. were recorded. There was a significant (p < .05) reduction in initial mycofloral population by an average of 2.2 log cycles as well as in species numbers with increasing doses of radiation. Radiation sensitivity (D10 values) also ranged between 1.68–2.78 kGy. Gamma irradiation treatment is one way which can enhance food safety through the reduction in potential pathogens and has been recommended as part of a comprehensive program to enhance food safety.

Impact of gamma radiation on the microbiological quality of smoke dry shrimp (Penaeus notialis) from three different water sources in Ghana.

Abstract Shrimps are one of the most important commodities of the global fishery trade, are consumed by humans and also used in formulation of feed for animals to enhance nutrition. Enumeration and identification of fungi and bacteria present on shrimp was checked. Gamma radiation doses of 0, 4, 8 and 10 kGy at a dose rate of 1.7 kGy/h from a Cobalt-60 source (SLL-515, Hungary) was evaluated. Mycological analysis was done by direct plating method on Oxytetracycline Glucose Yeast Extract and Dichloran Rose Bengal Chloramphenicol (DRBC) media. Bacteriological analysis was done by decimal reduction method on Plate Count Agar. Some toxigenic species of the genus Aspergillus (A. alutaceus, A. flavus, A. candidus and A. fumigatus), Fusarium (F. verticillioides) and Penicillium (P. expansum, P. citrinum and P. cyclopium) were isolated from the shrimp. Comparatively higher initial fungal and bacterial counts of 5.0–5.4 log 10 CFU/g and 4.3–4.7 log 10 CFU/g, respectively, were recorded for non-pretreated while lower counts of 1.7–2 and 1.6–2.1 log 10 CFU/g were recorded for pretreated smoked dry shrimp. Gamma radiation significantly (P < 0.05) reduced initial total fungal and bacterial populations by an average of 3 and 2.5 log cycles, respectively.

Physicochemical, functional and sensory attributes of milk prepared from irradiated tiger nut (Cyperus esculentus L.)

Abstract Five tiger nut (Cyperus esculentus L.) cultivars were collected from four different regions of Ghana and irradiated. The aim of this study was to evaluate some physicochemical, functional and sensory qualities of milk produced from irradiated tiger nut samples. Analysis was carried out for pH, total solids, moisture, sugar brix and viscosity. Finally the consumer acceptability of the milk prepared from the nuts was determined by a taste panel using the parameters of colour, taste, aroma, mouth feel and overall acceptability. The sugar content varied from 6.0±0.3% (Techiman) to 15.00±1.00% (Asebu Ekroful) depending on the irradiation dose applied. Generally, increase in dose increased the sugar availability but decreased viscosity of the milk prepared from the nuts. The milk with the highest viscosity was from Kwahu Aduamoa and Techiman with the least viscosity from Bawjiase. Generally, no significant difference was detected by the sensory panellists with regard to mouth feel and taste among the milk samples prepared from the various tiger nut cultivars.

Use of Pleurotus eous Strain P-31 Spent Mushroom Compost (SMC) as Soil Conditioner on the Growth and Yield Performance of Capsicum annuum L. and Solanum lycopersicon L. Seedlings under Greenhouse Conditions in Ghana

The objective of this study was to investigate the influence of spent mushroom compost of Pleurotus eous strain P-31 on the growth and yield performance of pepper and tomato seedlings under greenhouse conditions. Sandy loam soil was combined with different percentages of SMC to obtain the following combinations (0, 5, 10, 15, 20, 25 and 30) %. Lower concentrations SMC5, SMC10 and SMC15 promoted vegetative growth (plant height, leaf area, chlorophyll content, number of leaves and axillary branches) of the two test plants. Tomato seedlings grown in SMC10 recorded the highest plant height (50.3 ± 7.2cm); leaf area (378.8 ± 1.2cm2); number of floral buds (51) and flowers (28) whereas SMC5 recorded the highest chlorophyll content 34.1 ± 0.9CCI though SMC15 recorded the highest number of leaves (8). Tomato seedlings grown in SMC30 produced both the maximum number of fruits (8) with corresponding high weight (34.2 ± 7.7g). Pepper seedlings grown in lower concentrations (SMC5–15) recorded the highest plant heights (29.8–30.8cm), chlorophyll content (20.3CCI) and leaf area (53.5–66.2 cm2). Although the different combinations of sandy loam soil and SMC did not significantly (p ≥ 0.05) affect the number of axillary branches developed; different combinations significantly (p ≤ 0.05) affected the number of floral bud, flower and fruit, weight of fruits formed and value of each of these increased with increasing percentage of SMC. Pepper seedlings grown on SMC30 recorded the maximum number of floral buds (32.0 ± 3.6), number of flowers (19.4 ± 1.3), number of fruits (10.8 ± 1.2) and weight of fruits (31.9 ± 3.4g). Tomato seedlings raised on SMC100 (spent mushroom compost only) and soil only did not significantly (p ≥ 0.05) differ from each other however, was statistically significant (p ≤ 0.05) from amended sandy loam soil by all criteria investigated. The study shows that SMC provide favourable soil conditioners for the cultivation of fruits, vegetables and foliage crops as it improved growth and yield of tomato and pepper seedlings.

Nutritional and shelf-life studies of dry smoked and gamma irradiated shrimps (Penaeus notialis) from three different water sources in Ghana

Abstract Shrimps are mostly used in its dried state for several purposes in Ghana. They are food for several decades, used in many culinary dishes including baby foods as well as one of the main ingredients in the famous pepper sauce and can also be used in various foods to enhance flavor. Proximate composition of shrimps from three water sources: sea, lagoon and river was evaluated according to standard procedures of AOAC after exposure to gamma ionizing radiation from a Cobalt 60 source (SL 515, Hungary). Radiation doses used were 0, 4, 8 and 10 kGy at a dose rate of 1.7 kGy/h. Protein content ranged from 27.40 ± 1.30% to 34.35 ± 1.30%, ash 13.80 ± 0.09% to 15.42 ± 0.09%, fat 0.90 ± 0.01% to 1.72 ± 0.01% and moisture 9.36 ± 0.06% to 12.92 ± 0.06%. From the sea, river and lagoon, protein content ranged between 25.93 ± 1.13% and 34.42 ± 1.13%, ash 11.85 ± 0.08% and 18.25 ± 0.08%, fat 0.76 ± 0.01% and 1.83 ± 0.01% and moisture 9.22 ± 0.05% and 12.72 ± 0.05%. After 4 months of storage, there was a significant (p < 0.05) increase in protein and ash contents while fat and moisture contents decreased. The use of gamma irradiation technology in food processing should be encouraged as it does not affect nutrients.

Comparative Studies on the Mineral Elemental Composition of Gamma Irradiated Smoked Shrimps ( Penaeus notialis ) from 3 Different Water Sources in Ghana

Dry and smoked shrimp constitute an important nutrient supplement for the populace in Ghana. Shrimp continues to represent one of the safest forms of muscle protein consumed in the world. Despite this safety record, shrimp have a high tolerance to toxins in polluted areas. The effect of irradiation on the nutrient and mineral elements including heavy metals were examined after storage for 4 months in dense polyethylene bowls. Elemental composition was estimated by Atomic Absorption Spectrometry (AAS). The Flame Photometer (FP) was used in the determination of Sodium and Potassium. There were clear differences in the concentration of heavy metals, and macro nutrients (Mg, K, Na, Zn) due to influence of the type of water body they dwelled in. Irradiation had some or no effect on the concentration of these listed elemental and components, but there were interactions between sources of shrimp, storage time and irradiation dose in some instances. Multivariate analysis of elemental composition showed that, accumulation of Fe, Cu, Zn, and N was generally attended by uptake of Pb, Cr, Na, and K. The order of elemental concentration (in decreasing order) was: Fe  Cu  Zn  N  Mn Pb Cr Na  K  Ni  Cd.

Nutritional Qualities and Shelf Life Extension of Gamma Irradiated Dried Pleurotus ostreatus (Jacq. Ex. Fr.) Kummer Preserved in Two Different Storage Packs

Pleurotus ostreatus has high nutritional value as an important source of protein, carbohydrates, vitamins, mineral elements and is among most favorite mushrooms of the world. Proximate composition and metabolizable energy of these mushrooms were evaluated for their dietary value. Fruit bodies were solar dried to a moisture content of 12% and exposed to low dose ionizing (gamma) radiations of 0, 0.5, 1, 1.5 and 2 kGy at a dose rate of 1.7kGy/hr and stored in polyethylene and polypropylene packs at room temperature (28- 30℃) for a period of 12 months. Values ranged 14.11- 15.80%, 6.16- 8.31%, 0.65- 1.24%, 13.56- 15.39%, 12.51- 15.25%, 61.16- 65.50% respectively for moisture, ash, fat, fibre, protein and carbohydrate. Metabolizable energy also ranged 247.8- 284.6 Kcal./100g for 12 months storage. Although there were some significant (p<0.05) changes observed for some nutrients due to gamma irradiation and storage, the results obtained showed that the integrity of these nutrients in this mushroom were minimally affected as no adverse effects were observed.