Dioscorea Cayenensis Research Articles

Stochastic Production Frontier Analysis and Technical Efficiency of Yellow Yam (Dioscorea cayenensis) Farmers in Orhiowmon Local Government Area of Edo State, Nigeria

Stochastic Production Frontier Analysis and Technical Efficiency of Yellow Yam (Dioscorea cayenensis) Farmers in Orhiowmon Local Government Area of Edo State, Nigeria

Biological potentials of Landolphia owariensis leaf methanolic extract against pathogenic fungi isolates from different Dioscorea species

Abstract Regarding economic significance, the Dioscoreaceae family, which includes the well-known Dioscorea (yam) species, is the fourth most important tuber crop globally. A basic meal found all across the world, yams encourage and ensure the food security of households. Although they are challenging to preserve and store however a post-harvest deterioration control must be developed. Over the years, Nigerian farmers have employed medicinal herbs to manage post-harvest pest invasion; nevertheless, the scientific basis for this fungal management has not yet been well documented. As a result, Landolphia owarensis leaf extract was used as a biological control, and fungi were isolated from Dioscorea cayenensis, Dioscorea alata, and Discorea rotundata. Samples of yam tubers – both rotten and healthy – were procured in the markets and brought to the lab for fungus isolation and identification. Leaves of Landolphia oweriensis were collected, air-dried, milled, and macerated in pure methanol for 72 h, extracted and concentrated with a rotary evaporator. The agar-well diffusion method was used for the biological control assay against the fungal isolates. The biological control results were presented as mean ± SD (standard deviation) while analysis of variance (Anova) was used to deduce least significant difference (LSD). A total number of 605 fungi isolates were observed in which D. cayenensis had the highest, 50.58 %, D. alata and Discorea rotundata 24.71 % respectively. Aspergillus niger and Aspergillus fumigatus were found in the three species while Aspergillus flavus, Rhizopus stolonifer, Collentotricum spp. and Penicillium spp. in either of the species. L. owarensis methanolic leaves extracts possesses biological potentials against Colletotrium spp., A. fumigatus, A. niger and A. flavus only. The problem of postharvest fungal invasion of Dioscorea species can be solved with the inhibition observed with L. owarensis methanolic leaves extracts as a biological control measure thereby sustaining food security in the world.

Resistance of Dried Chips of Three Yam Cultivars to Damage by Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae)

Yam (Dioscorea spp) is one of the most common tuber crops consumed by man due to its nutritional benefits. Yam tubers are often processed into products like Dry Yam Chips (DYC) to minimize postharvest losses. The crop could be processed into other products to reduce perishability and scarcity at certain periods. The insect is mainly controlled with conventional insecticides. However, use of conventional insecticide in preserving DYC is contentious due to concerns about undesirable effects on consumers. This has necessitated the search for safer and more effective control strategies such as resistance traits that is innate. The study was therefore conducted to evaluate the resistance of three yam species (Dioscorea cayenensis, D. rotundata, and D. alata) used in making DYC to infestation and damage by Larger Grain Borer (LGB). Two hundred (200) g of parboiled DYC were weighed into 250 ml Kilner jars and separately infested with twenty adult LGB of 0-5 days old. The treatments were replicated four times and arranged on the experimental table using Completely Randomized Design (CRD). At 90 days post-infestation, the insects were sieved out to separate insects from DYC. Data were collected on weight loss of DYC, damage to DYC, adult mortality of LGB, dust of DYC, and number of emerged LGB. The percentage damage of LGB to DYC of D. alata and D. rotundata was 100.00% and 96.43%, respectively, which were not significantly (p> 0.05) different from each other. The percentage weight loss (70.61) of DYC of D. alata was significantly (p< 0.05) higher than the weight loss in D. cayenensis (28.63) and D. rotundata (46.27). The percent weight loss in the DYC of D. cayenensis was significantly (p< 0.05) lower than the weight loss in DYC of D. alata (70.61) and D. rotundata (46.27). The number of adult LGB (539.80) in the DYC of D. alata was significantly (p < 0.05) higher than the number of the insect in D. cayenensis (117.8) and D. rotundata (216.80). The number of adult mortality of LGB in the DYC of D. alata (38.50) and D. cayenensis (21.12) is comparable, but significantly lower than number of adult mortality of the insect in D. rotundata (41.50) DYC. The number of the insect larvae in DYC of D. cayenensis (4.25) was significantly (p< 0.05) lower than the number of the larvae of LGB in DYC of D. alata (30.00) and D. rotundata (21.00). DYC of D. cayenensis and D. rotundata were moderately resistant to damage by LGB and could be use in preparation of DYC to mitigate damage of LGB to DYC in storage before use.

Pratylenchus zeae in yam, Dioscorea cayenensis and D. alata, in Brazil

Pratylenchus zeae in yam, Dioscorea cayenensis and D. alata, in Brazil

Effect of Atmospheric Deposition of Pollutants on the Concentration of Trace Metals on Some Sun-Dried Food Items Dried at a Non-Vehicular Corridor in Ile-Ife Nigeria

The effect of atmospheric pollution on some sun-dried food items in Ile-Ife, Nigeria was investigated. Six farm produce: cassava (Manihot esculenta), plantain (Musa x paradisiaca), white yam (Dioscorea rotundata), yellow yam (Dioscorea cayenensis), red cocoyam (Xanthosoma sagittifolium) and sweet potato (Ipomoea batatas) were exposed, for different hours (0 h, 8 h, 20 h, 32 h, 42 h), to the sun at a location far from vehicular activities. Exposed samples were digested and analyzed for Cu, Zn, Ni, Mn, Cd, and Pb using Atomic Absorption Spectroscopy (AAS). The concentration of Cu, in exposed samples, ranged from mg/kg in sweet potato (32 h exposure) to mg/kg in cocoyam (0 h exposure), while the concentration of Zn ranged from mg/kg in plantain (42 h exposure) to mg/kg in cocoyam (0 h exposure). On the other hand, the concentration of Mn ranged from mg/kg in plantain (42 h exposure) to mg/kg in sweet potato (0 h exposure). Furthermore, the concentration of Ni ranged from mg/kg in yellow yam (32 h exposure) to mg/kg in the plantain (32 h exposure). The concentration of Cd ranged from mg/kg in cassava (32 h exposure) to mg/kg in plantain (20 h exposure). In comparison, the concentration of Pb ranged from mg/kg in cassava (20 h exposure) to mg/kg in plantain (20 h exposure). The study observed that there was no particular pattern in the effect of atmospheric deposition of the pollutants, Cu, Zn, Ni, Mn, Cd, and Pb, on the concentration of these pollutants in the sun-dried farm products, for the different exposure hours. The study believed that the non-uniform pattern could result from differences in the concentrations of the pollutants in the atmosphere. It could also be a result of the different water retention abilities of the respective farm products, which may impact the absorption or evaporation of deposited pollutants on these farm products.

Effects of Poultry Manure on Soil Fertility, Growth and Yield of White Yam and Yellow Yam

Field experiments were conducted at Owo in the forest-savanna transition zone of southwestern Nigeria during 2007 and 2008cropping seasons to study the effect of different levels of poultry manure(0, 10, 20, 30 and 40 t/ha) on soil fertility, leaf nutrient content, growthand tuber yield of two species of yam; namely, white yam (Dioscorearotundata Poir) and yellow yam (Dioscorea cayenensis Lam). Thetreatments were factorially arranged in a randomized block design withthree replications. The soil was deficient in organic matter (OM), total N,available P, exchangeable K, Ca and Mg. The results showed that poultrymanure increased soil and leaf N, P, K, Ca and Mg, and soil OM, growthand tuber yield of the yams compared with the control treatments. Whiteyam produced significantly higher yield than yellow yam. Compared withyellow yam, white yam increased tuber yield by 19%, 26%, 36%, 3% and12%, respectively, for 0, 10, 20, 30 and 40 t/ha poultry manure.Application of poultry manure at 20 t/ha and 30 t/ha significantlyimproved growth and tuber yield of white yam and yellow yam,respectively, compared with the other treatments. These levels of poultrymanure are, therefore, recommended for the two yam species in forest-savanna transition zone of southwest Nigeria. Recommendations ofmanure for yam production should be variety specific.

Geographic distribution and uses of species of the genus Dioscorea

Species of the genus Dioscorea are widely distributed throughout the world. It is a resource used in different countries because theyproduce tubers that offer numerous benefits for human health due to their diosgenin content, a compound that is used as: anti-inflammatory, androgenic, estrogenic and in the preparation of contraceptive drugs; It is also mentioned that these compounds havecytotoxic, antitumor, antifungal, immunoregulatory, hypoglycemic and cardiovascular properties, they are also used for theprevention and treatment of degenerative diseases. Species such as Dioscorea bulbifera, Dioscorea cayenensis, Dioscorea colletii,Dioscorea deltoidea, Dioscorea futschauensis, Dioscorea nipponica, Dioscorea panthaica, Dioscorea parviflora, Dioscoreapolygonoides, Dioscorea pseudojaponica, Dioscorea spongiosa, Dioscorea villosa, Dioscorea composita, Dioscorea zingiberensis,produce a higher concentration of diosgenin. The tubers and roots of this group are part of the oldest foods consumed by humans,given their high nutritional, ecological and economic level. In many tropical countries, the use of various tubers and roots of thegenus Dioscorea play a very important role as a main source of energy and essential nutrients at low cost, they are also used asfodder for livestock and a source of income. This plant are rich in starch, vitamins, minerals and lipids, and have the potential tofight hunger in third world countries. Currently there is little or no knowledge in Mexico on how to cultivate these species.

Host status of weeds for Pratylenchus coffeae

Background Populations of yam dry rot nematodes Scutellonema bradys, Pratylenchus coffeae and P. brachyurus can be sustained on weed hosts. Objective Evaluate the reaction of 10 weeds frequently found in Alagoas to P. coffeae under greenhouse conditions. Methods Two experiments were carried out in a completely randomized design, with 11 treatments, constituted of 10 weed species and the control (Dioscorea cayenensis) with eight replications. Plants were inoculated with 2,000 nematode specimens, nematode populations were evaluated in roots and soil [...]

Proximate Composition, Levels of Some Essential Mineral Elements and Anti-Nutritional Components of Some Yam Species Found in Minna, Niger State

Samples of Dioscorea dumenturom, Dioscorea rotundata and Dioscorea cayenensis were investigated for their proximate composition, anti-nutritional and mineral contents using standard analytical methods. These varieties of Dioscorea analysed showed a significant difference (P≤0.05) amongst them. However, from the results, it was observed that Dioscorea rotundata had the highest ash (8.05±0.05 %) and crude fibre content (13.11±0.10 %) which indicates that it contains more mineral stuffing and is best for softening of stool. Dioscorea cayenensis had the highest fat content (16.31±0.30 %), indicating that it is a better source of calories than other yam species analysed. Dioscorea dumenturom had the lowest moisture content (3.51±0.01 %) as well as the highest crude protein (12.29±0.01 %) and carbohydrates (69.04±0.10 %) than other yam species analysed, indicating its longer shelf-life, high bodybuilding capacity and better source of energy than other yam species analysed. The anti-nutritional constituent of alkaloid and tannin were lowest in Dioscorea cayenensis while Dioscorea rotundata had the least cyanide, phytate and oxalate content. This implies that these particular yams are safer for consumption. The elemental analysis in mg/100g indicated that the yam species contained appreciable levels of essential minerals, with Dioscorea dumenturom having the highest sodium, calcium, iron, potassium, phosphorous and magnesium concentration of 32.05±0.07 mg/100g,190.57±0.01mg/100g, 5.98±0.03 mg/100g, 80.12±0.17 mg/100g, 237.10±0.48 mg/100g and 100.22±0.03 mg/100g respectively. All these mineral concentrations exist within the permissible limit of WHO and hence indicate that the yam species can serve as a good source of minerals.

Evaluation of some phytochemicals in raw and cooked Ipomea batatas (Lam), (Sweet potato), Solanum tuberosum (Irish potato) and Dioscorea cayenensis (Yellow yam)

Cooking induces numerous phytochemical changes in food. This study is aimed at determining the amount of phytochemicals present in raw and cooked sweet potato, Irish potato and yellow yam. The amount of tannin, alkaloids, saponin, flavonoids and phenol were determined in raw and cooked samples of each food crop. The result showed that tannin, alkaloids, saponin, flavonoids, phenol contents was high in Irish potato and sweet potato but was far much present in Irish potato, while it was seen in minute quantity in yellow yam. The values obtained for each phytochemicals in each food sample raw and cooked respectively, in mg/100g were; Yellow yam: Tannins (0.10 and Nil), Alkaloids (2.00 and 0.51), Flavonoids (1.18 and 0.87), Saponins (2.00 and 1.02) and Phenols (0.72 and 0.10). Sweet potato: Tannins (0.32 and 0.28), Alkaloids (2.17 and 0.62), Saponins (2.10 and1.58), Flavonoids (1.28 and 0.97) and Phenols (1.42 and 0.72). Irish potato: Tannins (0.55 and 0.49), Alkaloids (2.17 and 0.81), Saponins (4.00 and 2.13), Flavonoids (5.00 and 2.91) and Phenols (2.00 and 0.91). The % loss of phytochemicals after cooking were; Yellow yam: Tannins (Nil), Alkaloids (74.5), Saponins (49.0), Flavonoids (26.3) and Phenols (86.1). Sweet potato: Tannins (12.5), Alkaloids (71.4), Saponins (24.8), Flavonoids (24.2) and Phenols (49.3). Irish potato: Tannins (10.0), Alkaloids (62.7), Saponins (46.8), Flavonoids (41.8) and Phenols (54.5). These results indicate that boiling of the samples seems to reduce their phytochemical contents as the raw samples showed higher amounts of the phytochemicals. The results also revealed that Tannins are more stable to heat across the 3 food samples, followed by Flavonoids, Saponins, Phenols and Alkaloids. The loss in some of the phytochemicals after cooking did not significantly affect the nutritional quality of the food samples.

West African Crop Wild Relative Checklist, Prioritization and Inventory

Crop wild relatives (CWR) are wild plant taxa genetically related to domesticated crops with trait diversity that can be used in plant breeding to sustain food security. Prioritization is a prerequisite for the cost–effective conservation of CWR as it allows CWR in a checklist to be reduced to a manageable number for active conservation action. In this study, a partial CWR checklist comprising 1651 taxa was compiled for West Africa. Prioritization of the annotated CWR checklist was based on three criteria: (i) economic value of the related crop in West Africa, (ii) CWR genetic closeness to its related crop and (iii) threat status. After applying the three criteria using the parallel method of prioritization, 102 priority CWR were selected for active conservation action. The priority CWR are related to food crops that are nationally, regionally and globally important, such as white guinea yam (Dioscorea cayenensis subsp. rotundata (Poir) J. Miège), cassava (Manihot esculenta Crantz), rice (Oryza sativa L.), wheat (Triticum aestivum L.), cowpea (Vigna unguiculata (L.) Walp.), sweet potato (Ipomea batatas (L.) Lam.), common bean (Phaseolus vulgaris L.) and sorghum (Sorghum bicolor (L.) Moench). This CWR checklist and prioritization will help in the development of a regional conservation action plan for West Africa.

Proximate, Mineral and Phenol Content of Dioscorea Rotundata Var. Amula, Dioscorea Cayenensis Var. Igangan-Alo from Farmers’ Plots and Bounty-Fertilized, Infected with Botryodiplodia Theobromae Pat.

Fertilizer effects on infection and weight loss by Botryodiplodia theobromae Pat, was determined in white guinea yam Dioscorea rotundata variety Amula from the middle belt-region of Nigeria, and yellow guinea yam D. cayenensis variety Igangan/Alo from South West Nigeria. Tubers of both varieties were sourced from farmers’ plots from within Ogun State ( South West Nigeria) where they had been planted on three or more years previously fallowed plots, and harvested at six months after planting. Another lot of tubers of both varieties were sourced from a yam project plot at the Teaching and Research farms of the Directorate of University Farms (DUFARMS), Federal University of Agriculture (FUNAAB) Abeokuta, where they had been fertilized at the rate of 0.60 ml l-1 of Bounty fertilizer, an 8-mineral component fertilizer, and harvested also at six months after planting. Tubers of both varieties from farmers’ plots were analysed for proximate content (dry matter, moisture, ash, fat, crude protein, crude fibre and carbohydrate) phenol content and ten minerals namely Ca, N, P, K, Mg, Fe, Mn, S, Zn and B. Another set of tubers of the two varieties from farmers plots, as well as those from the Bounty-fertilized yam project plot, were inoculated with Botryodiplodia theobromae in an infection and weight loss experiment. The infection and weight loss experiment was a 2 by 2 factorial arranged in RCBD (randomized complete block design) with 4 treatment combinations and 5 replications. Tubers of both varieties from both sources inoculated with a 7-day old pure culture of B. theobromae were the four treatment combinations. Incubation period was 3 weeks. Infection in Amula (white guinea yam) was over 2500% higher than in the yellow guinea yam, Igangan. Phenol (107.89 mg/100 gdm) and calcium (16.85 mg/100 gdm) were higher in Igangan than in Amula (89.04 and 16.70 mg/100gdm respectively), and is adduced as the reason for the high infection in variety Amula. Weight loss however was 154% higher in Igangan than in Amula. Crude fibre had a negative significant correlation with weight loss (r = -0.9285, P=0.001), and crude fibre with the value 4.49% dm was higher in variety Amula than in variety Igangan (4.02%dm). This is responsible for the higher weight loss in var. Igangan. Phenol content also had a significant negative correlation with weight loss (r = -0.9586, P = 0.05), suggesting that the effect of high crude fibre in reducing weight loss outweighs that of phenol in reducing weight loss. There was high reduction of infection in the Bounty-fertilized tubers, 3.72% compared to farmers’ plot tubers which had 27.22%. Weight loss was also 0% in Bounty-fertilized tubers compared to a high 63.54% in the tubers from farmers’ plots. This indicates that the 8-mineral component fertilizer, Bounty will prolong shelf life in the white and yellow guinea yams Amula and Igangan. Five minerals namely Mg, K, Zn, Mn and B had significant correlation with weight loss (r = 0.9461, 0.9802, 0.9214, 0.9898 and 0.9122) respectively. Three of these minerals namely Zn, Mn and B content were all low with mean values of 0.25, 0.44 and 0.07 mg/100gdm respectively but Mg and K were relatively higher with mean values of 21.59 and 806.67mg/100gdm respectively. This suggests that mineral nutrition to enhance prolonged shelf life in D. rotundata var. Amula and D. cayanensis var. Igangan may be established with a balance of Mg, Zn, Mn and B in lower proportions than K, as potassium is essential in optimum yield in Dioscorea species.

Nutritional potential of underutilized edible plant species in coffee agroforestry systems of Yayu, southwestern Ethiopia

Ethiopia is confronted with the paradox of hosting hundreds of edible plants and having high food and nutritional insecurity. Meals are mainly made up of staples and often lack of protein and micronutrients. Therefore, a large section of the population, particularly children and women, are malnourished. We hypothesize that wild edible plant species can contribute to fulfil the micronutrient demands of local people. Hence, we assessed the nutritional potential of underutilized edible plant species growing in understories of coffee agroforestry systems of southwestern Ethiopia. An ethnobotanical household survey (n = 300) documented the edible existing plants; and a promising subset of them (n = 12) was analysed for nutrient and antinutritional factor content in the lab. All 12 species, except fruits, have higher calcium, iron and zinc contents compared to regularly cultivated crops. Vitamin C was high in Syzygium guineense (330.72 mg/100 g edible parts or EP) and Rubus apetalus (294.19 mg/100 g). Beta-carotene ranged from 9.2 to 75 µg retinol activity equivalent (RAE) /100 g 25 among all species, but was exceptionally high in Rubus apetalus (161.7 µg RAE/100 g). Concerning the antinutritional factors, phytate content varied from 31.06 to 601.65 µg/100 g, being lower in Dioscorea prehensilis (31.06 µg/100 g) and D. alata (90.17 µg/100 g) compared to Carissa spinarum (601.65 µg/100 g) and Solanum nigrum (536.48 µg/100 g). Thus, we conclude that the assessed underutilized species are potential sources of dietary nutrients locally needed, and are notable Amaranthus graecizans, Portulaca oleracea and Dioscorea cayenensis as providers of Ca, Fe and Zn, and the fruit Rubus apetalus of provitamin A.

Adaptation of plants derived from cultivated yam of Dioscorea cayenensis–D. rotundata complex species seeds germination in two agroecological zones of Benin

Vegetative propagation of plants promotes the accumulation of viruses in plant material; this causes the loss of vigor and consequently the drop of vegetable yield. Keep up productivity level of vegetatively propagated plants; it is therefore important to regenerate genetic material by sexual reproduction to improve the biodiversity. The main objective of this study is to improve yam seeds by sexual way, specifically to assess the response of seedlings from yam seeds in two agroecological areas, area IV (Djougou), in Sudanese climate and area V (Bantè), in transition climate. Seedling were transplanted in this agroecological areas using a completely Randomized design with three replications. Data was analyzed using one way ANOVA at 5% level of significance and a mean comparison test. Seedling survival rate is significantly different, 55.41% in zone IV and 23.60% in zone V, but the rate of tuberization of the two areas is similar, 55.63%; of zone IV and 57.62%; of zone V. The average of the tubers length and their weight are respectively 13.21 cm and 24.87 ± 19.22 g in zone IV and 8.95 cm and 10.30 ± 9.91 g in zone V. This results show that microtubers produced from the seeds show a high degree of heterogeneity, and, varieties creation and improvement is possible from the seeds. This technique would promote the selection of varieties adapted to current climatic conditions.

Adaptation of plants derived from cultivated yam of Dioscorea cayenensis–D. rotundata complex species seeds germination in two agroecological zones of Benin

Adaptation of plants derived from cultivated yam of Dioscorea cayenensis–D. rotundata complex species seeds germination in two agroecological zones of Benin

Current Status of Yam (Dioscorea Sp) Genetic Resources-Case Study of Selected Locations in South-West Nigeria

Yam is an important tuber crop in Nigeria. Some locations in South west Nigeria (Oyo State, Ondo State, Osun State, and Ogun State) were surveyed to find out the existence and the abundance of diversity of white guinea yam (Dioscorea rotundata). It was discovered that there are also diversity in other species of landrace yams (Dioscorea cayenensis, Dioscorea alata, Dioscorea dumentorum). One unidentified species of yam was found in Ondo State. This species also exist in Osun State. Some of the yam diversities are endangered. Genetic erosion of these yam diversities is imminent because of the decline of the traditional farmers growing these diversities; also because of modern commercial farms that tend to mono-cropping of improved variety and also because of problem of storage of yams and especially ex-situ conservation of yam genetic resources of yam in Nigeria.

Estimation of Phytochemical in Yam Flours and Sensory Attribute of Poundo Yam Produced from Yam and Moringa oleifera Seed Meal Blends

The sensory characteristic can be quantified and defined by the use of the descriptive profile. A different cultivar of yam can be used for the production of poundo yam. The standard of a product is determined by the evaluation and its acceptability by a taste panelist. Four cultivars of yam; Dioscorea alata, Dioscorea cayenensis, Dioscorea rotundata and Dioscorea bulbifera were sourced and processed into flour. Moringa seed oleifera was defatted and the cake was blended at a different concentration of 5% and 10% with the yam flour. The qualitative phytochemical investigation of the yam flour and Moringa oleifera seed revealed the presence of, alkaloids, steroids, terpenoid oxalate, anthraquinone, phenol, saponins, tannins and flavonoids. Quantitative analysis showed that among the control samples Dioscorea alata (DAC), Dioscorea Dioscorea bulbifera (DBC), cayenensis (DCC) and Dioscorea rotundata (DRC). DRC and DAC have the highest values in the total phenol and total flavonoids. Dioscorea cayenensis recorded the highest value in steroid and saponin content. The flavonoids, steroid and terpenoid were improved by the inclusion of moringa seed meal at 5% and 10%. The result of the sensory analysis revealed that panellist preferred DRC in term of moldability, texture, taste and general acceptability. However, the samples with moringa seed meal at 5% and 10% inclusion compete favourably with the control samples. The inclusion of Moringa oleifera seed meal at 10% improved the pounded yam and was more accepted than the 5% in term of general acceptability.

Evaluation of Instant Pounded Yam Flour Produced from Yellow Yam (Dioscorea Cayenensis)

This study was aimed at determining the chemical, pasting, functional and organoleptic properties of instant pounded yam flour (IPYF) produced from Dioscorea cayenensis. Fresh yams obtained from a market in Akure, Ondo State, Nigeria, were peeled, washed, sliced to 2, 4 and 6 mm thicknesses with FUTA Slicer. A half portion was blanched at 90 °C and other at 100 °C for 10, 15 and 20 minutes, drained, dried using hot air oven at 60 °C and the dried chips were milled, sieved and package in white polythene bag. Control samples were prepared using Dioscorea rotundata. The samples were analysed for physicochemical, functional, pasting, minerals and organoleptic properties. All data obtained were subjected to statistical analysis. The result of the study showed that IPYF produced from Dioscorea cayenensis had significant higher values in all parameters than the once from Dioscorea rotundata, except in fat, dispersibility and organoleptic properties. It indicates that, Dioscorea cayenensis has good qualities than Dioscorea rotundata when processed to IPYF based on physicochemical, functional and pasting properties. IPYF of 4 mm at 100 oC for 10 minutes is recommended from yellow yam.

Comparative Studies on the Susceptibility of Three Tubers of Dioscorea Species to Dry Rot in Anyigba, Kogi State

Various yam species are cultivated but white yam (Dioscorea rotundata Poir.), water yam (Dioscorea alata L.) and yellow yam (Dioscorea cayenensis Lam.) are among the most cultivated in Nigeria. The Susceptibility of three tubers of Dioscorea species (D. rotundata, D. alata and D. cayenensis) to dry rot pathogens was investigated. Isolation was made from rotted tuber tissues, followed by pathogenicity test and identification of isolates; two fungal species Aspergillus niger and Rhizopus stolonifer were isolated and identified as the major fungi causing yam tuber dry rot in the study area. There was significant difference (P<0.05) in the susceptibility of the various Dioscorea tuber species studied to rot caused by Aspergillus niger [D. rotundata (20mm), D. alata (11mm) and D. cayenensis (3.5mm)] and Rhizopus stolonifer [ D. rotundata (17.5mm), D. alata (10mm) and D. cayenensis (2mm)]. The phytochemical contents of the three tubers of Dioscorea species examined also varied significantly, with the bioactive substances of D. cayenensis and D. alata relatively higher when compared to D. rotundata. Therefore, this research reveals that three metabolites; Saponin, Flavonoid and Tanin constitute the major trait for resistant ability of D. cayanesis and D. alata to dry rot causing pathogen. Therefore, it is necessary that the differences in susceptibility be considered when developing yam barns. Also, researchers should work on genetically improving the susceptible white yam (D. rotundata) which is commonly eaten by millions of Nigerians with a possibility of increasing the quantities of the deficient phytochemicals.

Binder and Disintegrant Performance of Native and Thermally Modified Dioscorea cayenensis Starches in Paracetamol Tablet Formulations

Binder and Disintegrant Performance of Native and Thermally Modified Dioscorea cayenensis Starches in Paracetamol Tablet Formulations