Dioscorea Cayenensis Research Articles

Near-infrared spectroscopy in vegetables and humans: An observational study.

Cerebral near-infrared spectroscopy (NIRS) of tissue oxygen saturation is claimed to be a surrogate marker for global cerebral perfusion. Increasingly, NIRS target-based therapy has been used during cardiac surgery in the hope of decreasing the incidence of adverse neurological outcome. We report NIRS values for some common vegetables and faculty at a world-class medical institution. Observational nonblinded study. Single tertiary care institution and local urban vegetable market. Five yams (Dioscorea cayenensis), five courgettes (Cucurbita pepo) and five butternut squashes (Cucurbita moschata) were studied. Five cardiothoracic surgeons and anaesthesiologists were the control group. None. NIRS value of each species. Mean NIRS value for the control group was 71% [95% confidence interval (CI) 68 to 74] and was similar to that of the yellow squashes [75% (95% CI 74 to 76)]. These values were significantly greater than the NIRS measurements of both the butternut squash and yam [63% (95% CI 62 to 64) and 64% (95% CI 63 to 65), respectively, P < 0.01]. Commonly eaten vegetables have NIRS measurements similar to those seen in healthy humans.

Microtuberization and Acclimatization in the Dioscorea cayenensis Thunb. by the Carbon Source

In this experiment, we investigated the effects of various carbon sources and concentrations on the microtuber induction and acclimatization of the yam (Dioscorea cayenensis). First, the effects of the in vitro carbon sources and concentrations on the microtuber induction were examined. The highest efficiency of the microtuber induction was obtained in the 7% sucrose treatment, whereas the glucose treatment shows no effect on the microtuber formation. Secondly, the effects of the survival rate and the microtuber formation rate after the acclimatization were examined. The diameter (6.1 mm) and fresh weight (0.5g) of the tuberous root are the highest in the pretreatment of the 7% sucrose. Although the survival rate of the pretreatment of the low concentration sucrose (3% sucrose) is 100 %, the growth and development were inhibited. These results suggest the 7% sucrose treatment is appropriate for the yam microtuber formation and acclimatization. In addition, this protocol could be used for the propagation of virus- or disease-free clones and the multiplication of elite yam cultivars.

A comparative assessment of nutrients and anti-nutrients contents of varieties of fried yam (&lt;i&gt;Dioscorea specie&lt;/i&gt;) commonly consumed in Nigeria

There is limited information on nutrients composition of Nigerian foods. As a result, nutrients intake from Nigerian foods is in most cases estimated using foreign food composition tables. This research determined and compared proximate composition, minerals and anti-nutrients in pre- boiled fried New and old White Yam ( Dioscorea rotundata ), Water Yam ( Dioscorea alata ) and Yellow Yam ( Dioscorea cayenensis ) purchased at Yankura market, Kano, Northwestern Nigeria. Samples were peeled, boiled and fried. Fried yam samples were analysed for moisture, protein, carbohydrate, fat, ash, fiber and mineral contents using methods of the Association of Official Analytical Chemist. Phytate and cyanide were estimated bytitration. Results were analyzed using ANOVA in GraphPad Instat software. New White Yam exhibited significantly (P<0.05) higher content in moisture (52.5 ± 8.40 g/100g), fiber (2.0 ± 0.02 g/100g), calcium (13.7 ± 0.5 mg/100g); lower concentration of phytate (11.3 ± 0.08 mg/kg) and moderate concentrations of other parameters studied. Water yam contains significantly (P<0.05) higher protein (5.77 ± 0.2 %), potassium (683 ± 3.6 mg/100g) and moderate amount of other parameters studied. Yellow Yam contains significantly (P<0.05) higher magnesium (16.3 ± 1.52 mg/100g), phytate (31.2 ± 0.40 mg), lower fiber (0.9 ± 0.03 g/100g) and moderate amount of other parameters. Old White Yam contains significantly (P<0.05) higher carbohydrate (37.47 ± 0.5 g/100g), lower cyanide (3.2 ± 0.15 mg/kg) and moderate amount of other parameters studied. The fried yam samples studied have variable amount of nutrients and anti-nutrients. Apart from being excellent energy sources, all yam samples studied could contribute to intake of micronutrients. Keywords: Fried yam, proximate content, micronutrients, anti-nutrients

NUTRITIONAL COMPOSITION OF DIOSCOREA HISPIDA FROM DIFFERENT LOCATIONS AROUND LEUSER ECOSYSTEM AREA

NUTRITIONAL COMPOSITION OF DIOSCOREA HISPIDA FROM DIFFERENT LOCATIONS AROUND LEUSER ECOSYSTEM AREA

Tuber Wild Plants of Shinasha People as Food and Medicine in Bullen District, Northwest of Ethiopia

Bullen district is noted for its rich diversity of plant species apart from wetlands to flood plains serving the habitat requirement of several inhabitant communities and is unique in its nature by having rich diversity of wild edible plants A number of cultivated tuber food plants such as Qocho Dioscorea cayenensis Anchote Coccinia abyssinica Sekuar Dinich Ipomoea batatas Dinich Plectranthus edulis Zingibil Zingiberof ficiaale and Godere Colocasia esculanta etc having their wild relatives such as Colocasia esculenta Curcuma bulbifera Dioscorea prehensilis Dioscorea hispida and Dioscorea oppositifolia etc are present in the district The present survey encompasses documentation previous of wild tuberous plant species belonging to family and genera tabulated with botanical name local name and family habit and habitat mode of consumption and medicinal uses

Characterizing genotypic variation in biochemical composition, anti-nutritional and mineral bioavailability of some Nigerian yam (Dioscorea spp.) land races.

The aim of this study was to characterize 43 genotypes from five yam species [Dioscorea rotundata (Poir), Dioscorea alata (Linn), Dioscorea bulbifera (Linn), Dioscorea cayenensis (Lam) and Dioscorea dumetorum (Kunith) Pax] which are major land races in Nigeria in terms of their chemical composition, nutritional, anti-nutritional and mineral bioavailability. Findings showed that there was genotypic variation in terms of chemical composition, mineral profile and bioavailability of the minerals among the germplasm. D. bulbifera had the highest cell wall carbohydrates, (cellulose: 3.2%, hemicelluloses, 2.1%, lignin, 1.1%, acid detergent fibre (ADF) 3.2%, neutral detergent fibre (NDF) 6.4%), D. rotundata had the highest oxalate (606mg/kg). In conclusion, intra and inter-species variations exist among the yam germplasm in terms of their chemical composition, anti-nutritional and mineral bioavailability. Phytate content of the yam genotypes did not affect the bioavailability of Zn but Ca was affected significantly. The Ox:Ca ratio in most of the yam varieties were below one, thus bioavailability of Ca in yam by oxalate is variety dependent.

Abstract 197: Anti-cancer activity of extract from the Jamaican round-leaf yellow yam (RLY2) (Dioscorea cayenensis)

Abstract The Jamaican Round-Leaf yellow yams (RLY2), Dioscorea cayenensis, are edible tubers, bulbils or rhizomes that are of considerable economic value and possess several health benefits. These RLY2 are a rich source of anti-oxidants, vitamins and phytochemicals. In addition to its nutritional value, the Jamaican populace regards RLY2 as an herbal medicine useful in treatment of diabetes mellitus, hypertension and certain kind of cancers. Chemical analysis of RLY2 revealed the presence of a myriad of bioactive ingredients that are likely to be lost due to the method of preparation for consumption. Thus, we hypothesized that mild extraction of RLY2 will preserved the bioactive analytes that give RLY2 its anti-cancer property. To test this hypothesis, different ethanolic extracts of RLY2 were prepared, and their bioactivity demonstrated in two models of prostate cancer. The present study demonstrates dosage and time-dependence inhibition in both the androgen sensitive LNCaP and androgen insensitive DU-145 prostate cancer cell lines. We observed that DU-145 was three-times more sensitive to RLY2 ethanol extract than LNCaP. Growth of LNCaP for 3-days with varying concentration of RLY2 ethanol extract resulted in an IC50 of 750 ppm (95% C.I. 726-791ppm), whereas DU-145 resulted in an IC 50 of 250 ppm (95% C.I. 236-281ppm). The maximum growth inhibition by RLY2 extract occurs within twenty-four hours for both LNCaP and DU-145 with no significant changes after 5-days. To determine the mechanism of toxicity by RLY2, we induced both LNCaP and DU-145 with RLY2 for 0-24h and prepared cells for flow cytometer analysis. The effect of RLY2 on cell cycle and degree of apoptosis will be discussed. Our data indicated that the ethanol extract of RLY2 was more sensitive toward androgen-insensitive prostate cancer. Thus, this study suggests that RLY2 contain bioactive chemical that may be used in grade II prostate adenocarcinoma represented by the DU-145 phenotype. Citation Format: Sasha-Gay A. Wright, Wesley G. Gray, Helen Asemota. Anti-cancer activity of extract from the Jamaican round-leaf yellow yam (RLY2) (Dioscorea cayenensis) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 197. doi:10.1158/1538-7445.AM2017-197

Re-defining the yam (Dioscorea spp.) core collection using morphological traits

AbstractDevelopment of core collection representing the diversity in the entire germplasm creates a better access and enhanced utilization of the main collection thus allowing rapid evaluation in crop improvement programs. Core collections are dynamic in nature and needs revisiting when additional germplasm and information becomes available. In the current study, an attempt was made to re-define the previously developed yam (Dioscorea spp) core collection using 56 morphological traits. Information on additional acquired germplasm and presence of duplicates or mislabelled accessions in the entire collection was also used. The re-defined core collection consisted of 843 accessions and represented about 20% of the entire collection. It included six Dioscorea species, of which accessions of Dioscorea rotundata are in the majority (73.54%) followed by Dioscorea alata (21.35%), Dioscorea bulbifera (1.66%), Dioscorea cayenensis (1.42%), Dioscorea dumetorum (1.42%) and Dioscorea esculenta (0.59%). The Shannon weaver diversity index and principal component analysis revealed the maximum diversity captured in the core from the base collection. This re-defined core collection is more valuable than the original core since it represents true-to-type accessions ensuring reliability for enhanced utilization of germplasm in yam improvement programs.

Nutritional Quality of Weaning Foods Formulated from Yam (&amp;lt;i&amp;gt;Dioscorea alata&amp;lt;/i&amp;gt; and &amp;lt;i&amp;gt;Dioscorea cayenensis&amp;lt;/i&amp;gt;) Composite Flours

Some potential weaning diets formulated from yam species <i>Dioscorea alata</i> variety <i>Bètè bètè</i> and <i>Dioscorea cayenensis</i> variety <i>Lokpa, soybean</i> and cassava have previously been evaluated. In this study, four different diets (unfermented flour made of <i>Dioscorea alata</i>, fermented flour made of <i>Dioscorea alata</i>, unfermented flour made of <i>Dioscorea cayenensis</i>, fermented flour made of <i>Dioscorea cayenensis</i>) were prepared and fed to weaning rats for a period of 28 days. The study aimed to find out the <i>in vivo</i> impact of these yam composite flours. The performance characteristics of the developed products were investigated and compared with those of <i>Cérélac</i> (a commercial weaning food).The body weight change (BWC) of rats fed the different diets was highest in the rats fed <i>Cérélac</i> (3.39 g) followed by rats fed the fermented composite flours (FBBF and FLOF; 1.97 and 2.00 g, respectively) and casein-based diets (2.48 g) and least in rats fed the unfermented composite flour diets (FBBNF and FLONF; 1.60 and 1.51 g, respectively). A similar trend was observed in the total feed and protein intakes of the experimental animals. Moreover, the rat fed fermented composite flours showed high Protein Efficiency Ratio (2.25 – 2.37), Biological Value (78.94 – 79.46), True Digestibility (80.11 – 92.28) and Net Protein Utilization (60.91 – 76.34), comparable to those obtained with the casein-fed rats. The present study have shown that the values obtained with the test diet, especially for the fermented composite flours compared favourably with the reference diets (<i>Cérélac</i> and casein) in all the parameters investigated and should be considered a good weaning diet from a nutritional point of view.

Effects of processing methods on nutrient and antinutrient composition of yellow yam (Dioscorea cayenensis) products

There is dearth of documented information on nutrient retention of Dioscorea cayenensis products. This study was carried out to evaluate effects of processing methods on nutrient and antinutrient retention of yellow yam products. Fresh Dioscorea cayenensis tubers were purchased from Bodija market in Ibadan, peeled, cut into small pieces, divided into nine portions. One portion was treated as raw sample, and others processed into local delicacies. All nine samples were analysed for proximate, mineral, vitamin and antinutrient composition using AOAC methods. Data were analysed using ANOVA at p=0.05. Raw yam contained 66.79g moisture, 2.62g crude protein, 0.27g lipid, 0.17g fibre, 0.63g ash, 29.69g carbohydrates, 262.30mg potassium, 61.53mg magnesium, 0.79mg iron, 0.39mg zinc, and yielded 108.26kcal energy with insignificant vitamin content/100g edible portion. Processing significantly improved macronutrients and energy content with significant reduction in all antinutrients of products (p<0.05). The yam products can serve as staple source of energy to consumers.

Genetic diversity and relationship of Guinea yam (Dioscorea cayenensis Lam.–D. rotundata Poir. complex) germplasm in Benin (West Africa) using microsatellite markers

Guinea yam (Dioscorea cayenensis–D. rotundata complex) is an important tuber crop that highly contributes to food security and poverty alleviation in Benin. The knowledge and understanding of the extent of genetic variation of Guinea yam germplasm is important for planning of the genetic conservation, and the utilisation of this resource. The objective of this study was to assess the genetic diversity and relationships of 64 yam landraces whose dried chips are considered as resistant to insect attacks using 41 simple sequence repeat. Among these primers, 13 were found to be polymorphic, giving 113 polymorphic alleles. The number of alleles per locus ranged from 4 (Ym50) to 13 (Ym29), with an average of 8.69. Unique allele was observed with some landraces (Singou and Tchakatchaka) and can be considered as unique gene and use in yam breeding program. The mean polymorphic information content values for all markers used was 0.76 and ranged between 0.58 and 0.91 in loci YM3 and YM32 respectively. The genetic distance of yam landraces ranged from 0.45 (Yasoubagarou) to 0.04 (Assinapeira and Alahina), indicating that the yam germplasm has a high degree of genetic diversity supported by an averagely observed heterozygosity of 0.78. Cluster analysis using unweighted pair group method with arithmetic average grouped the 64 yam landraces into two distinct clusters. This tendency was also observed in the principal coordinate analysis. The analysis of molecular variance revealed that 96 % of the variation was found within the population and only 4 % between the populations. Genetic diversity and relationship assessments among the 64 yam landraces of Benin could provide useful information for efficient use of these materials, especially for genetic improvement.

English

This study analyzed the morphological characteristics and agronomic potentials of yam varieties (Dioscorea spp.) collected across the Guinea Sudan transition zone of Benin. Dioscorea cayenensis - D. rotundata varieties were characterized as wingless; some varieties were spineless, others had few or dense, robust or thin, and short or prickled spines. There was variation in leaf shape, stem and leaf colour, tuber shapes and forking tendencies. The tuber flesh presented different colours, texture, oxidation colour, oxidation time, and ability to irritate. Dioscorea alata varieties were all spineless and showed winged stems, pentagonal or quadrangular. Various leaf and petiole colours, and tuber shapes were observed. On average, the mean Shannon-Weaver index was 0.86 for the external morphology of the tuber, 0.55 for tuber flesh characteristics, and 1.13 for stem and leaf morphology. The pooled mean yield varied between 0.89 and 3.30 kg/heap for the early maturing varieties of the D. cayenensis - D. rotundata, between 0.94 and 3.03 kg/heap for the late varieties, and ranged from 1.45 to 4.17 kg/heap for the D. alata varieties. The year effect was highly significant for variety-type group and species, and was larger than the genotypic effect. The genotype by year interaction effects were highly significant. Key words: Dioscorea spp., genotype by environment interaction, yield, yam varieties’ traits, Benin.

Response of yams exposed to different sources and doses of nitrogen fertilizers in the State of Maranhão, Brazil

This study was carried out at the State University of Maranhão, São Luís, Brazil from January to November 2012. We assessed the behavior of the yam Dioscorea cayenensis ‘Da Costa’, fertilized with different rates and sources of nitrogen (N). The experimental design was randomized, with treatments in a 6 × 2 factorial design. The factors were represented by six rates of N fertilization (0, 50, 100, 150, 200, and 250 kg·ha-1) and two sources (ammonium sulfate and urea) by using four replicates. We evaluated the mean mass, commercial root yield, leaf N content, starch content in the tubers, and percentage of tubers with symptoms of nematode infection (dry and thick skins). The maximum values for the mean masses of commercial tubers were 2.5 and 1.9 kg with doses of 130 and 160 kg of N ha-1 from ammonium sulfate and urea, respectively. Doses of 130 and 154.3 kg of N ha-1 produced the maximum yields of commercial tubers of 19.7 and 14.9 t·ha-1 with ammonium sulfate and urea fertilization, respectively. The maximum levels of foliar N by using urea and ammonium sulfate were 36.5 and 29.3 g·kg-1, respectively, at a dosage of 250 kg·ha-1. The maximum starch contents of 25.7 and 28.3 % were obtained at doses of 114 and 116 kg of N ha-1 of ammonium sulfate and urea, respectively. The percentage of tubers infected with nematodes was 10% when the N source was urea and 15.6% when the source was ammonium sulfate, both at a dosage of 250 kg·ha-1.

English

Yam is one of the most staple foods in West African countries and provides an important part of the energetic for people. This study examines chemical composition of Dioscorea cayenensis and Dioscorea rotundata Poir species dried yam chips obtained using two methods of production in Togo. Three local varieties of yams (Koukou, Keki and Laboco) were processed in chips and were sun dried (at 28-30°C) or oven-dried (at 50°C). Nutritive components (carbohydrates, protein fats, mineral salt, vitamin C and anti-nutritional factors) of yam chips were assessed and compared with those of fresh yam. Sugar is a major component of yam chips followed by proteins, vitamin, fats, mineral salt and anti-nutritionals factors. For the same variety of yam, the nutritional quality depends on the method of production followed and the drying methods. Key words: Yam chips, Dioscorea cayenensis, Dioscorea rotundata, nutritional potential.

English

Genetic diversity of 43 Dioscorea dumetorum accessions and two of Dioscorea cayenensis Lam as out-group species was evaluated for qualitative and quantitative traits in two different agro-climatic zones Baham (05°20.040' N/010°22.572’ E and 1634±3 masl, agro-ecological zone III with rainfall of 1500 to 2000 mm, and mean annual temperature of 19°C) and Ekona (04°12.773'N/009°19.425'E and 445±3 masl, agro-ecological zone IV with rainfall of 2500 to 4000 mm and mean annual temperature of 26°C). Forty one (41) morphological characters according to International Plant Genetic Resources Institute (IPGRI) descriptor, including nine quantitative and 32 qualitative characters were analyzed for multivariate analysis using cluster analysis, principal component analysis (PCA), and analysis of variance. For quantitative characters, cluster analysis revealed three major clusters. The first three components with eigen values > 1 contributed 83% of the variability. The PCA results indicate that traits which largely contributed to the variability within and between the accessions were stem length, leaf length, internode number, leaf width, harvest index, leaf number and internode length. Traits such as harvest index, internode number and stem length showed high heritability and high genetic advance. For qualitative traits, cluster and principal component analysis revealed two major clusters in Baham as well as in Ekona. The traits such as spines on stem base, spines on stem above base, spines length contributed to the variability within and between the accessions. However, the limits of morphological characters in the study of diversity have been detected. Key words: Dioscorea dumetorum, morphological traits, characterization, agro-climatic zone, Cameroon.

International Research Journal of Agriculture and Soil Science

Low multiplication ratio of yam and scarcity of planting materials are major constraints militating against sustainable yam production. In order to evaluate the behavior of the four various types of seeds of two species of yams Dioscorea cayenensis and Dioscorea rotundata, cultivated on the experimental ground of the Higher National Institute of Agronomy and Biotechnology (INSAB), a test was realized in a randomized complete block design with six replications. The samples were cut and three levels of each tuber were used: proximal, medial and distal parts of the tuber. The fragments of tuber and the whole tuber represent the various types of seed used in this work. The results showed significant (P<0.05) differences in number of plants emerged and time of emergence in a mixture of 40% soil and 60% sand three months and half after planting. For all species, the proximal parts sprouted earlier than the medium parts and then the distal parts. The fragmentation of tubers in three (3) parts can show the existence of a gradient along the tuber in its potential for sprouting and growth. There was a highly significant (P<0.05) difference between yield performances after nine (9) months of culture. This technique improves the production of tubers in both species.

English

A study was conducted in five yam-growing communities in the Forest Transition Agroecological Zone of Ghana to identify cultivated yam varieties, their distribution and intensity of cultivation and to document the rate and causes of landrace germplasm loss. Generally, the cultivated varieties ranged from 9 to 16 with a mean of 12. The most diversity was found in Sankore (Asunafo South District), followed by Sampa in the Jaman North District, Asantekwa in the Kintampo District, Ejura in the Ejura-Sekyedumase and Mim in the Atebubu/Amantin Districts with 16, 15, 12, 11 and 9 cultivated varieties respectively. Dioscorea rotundata is most widely cultivated species of yam followed by Dioscorea alata, Dioscorea cayenensis, Dioscorea praehensilis and Dioscorea bulbifera respectively. Factors such as good culinary characteristics, high yield, seed generation capacity, good storage characteristics and resistance to biotic and abiotic stresses were important criteria for selection of variety. The market and utilization were major determinants of continual cultivation of a variety or its neglect. Key words: Agro-morphological, cultural, environmental, Ghana, technological.

English

The adverse effect of synthetic pesticides on human health and the natural ecosystem necessitate the need to explore natural mechanisms of disease control in plants. This study evaluated the allelopathic potential of five biocontrol agents: Trichoderma longibrachiatum, Trichoderma asperellum, Bacillus subtilis, Bacillus cereus and Pseudomonas fluorescens in the control of six fungal pathogens associated with tuber rot of Dioscorea cayenensis. Rotten tuber samples were randomly collected across three agro-ecological zones (AEZs): humid rainforest (HF), derived savanna (DS), and southern Guinea savanna (SGS) in Nigeria. Biocontrol agents were isolated from the yam rhizosphere using the serial dilution method; the agar pairing method was used for the in vitro trials. The destructive sampling method was used to evaluate rot control by the antagonists in vivo. Aspergillus niger had the highest incidence of 64.71% across the HF, 52.08% across the DS, and 41.98% across the SGS. B. subtilis had the highest inhibitory zone of 16.7 &plusmn; 0.05% when paired with A. niger, 15.4 &plusmn; 0.01% with Lasiodiplodia theobromae, 14.0 &plusmn; 0.33% with Penicillium oxalicum, 7.1 &plusmn; 0.14% when paired with Rhizoctonia solani; 17.1 &plusmn; 0.11% with Sclerotium rolfsii, and 10.3 &plusmn; 0.94% with Fusarium oxysporum. All biocontrol agents significantly (P = 0.05) reduced rot development of the test pathogens relative to the control in the in vivo experiment. The establishment of a distinct zone of inhibition, especially by the bacterial antagonists attests to the fact that they produced allelochemical substances. Therefore, further research is recommended to evaluate the biochemical composition of these microbial metabolites, their level of toxicity, and fate in the environment. &nbsp; Key words: Allelopathic potential, biocontrol agents, tubers, allelochemicals. &nbsp

Participatory evaluation of Guinea yam (Dioscorea cayenensis Lam.–D. rotundata Poir. complex) landraces from Benin and agro-morphological characterization of cultivars tolerant to drought, high soil moisture and chips storage insects

Guinea yam (Dioscorea cayenensis Lam.–D. rotundata Poir. complex) is an important tuber crop that highly contributes to food security and poverty alleviation in Benin. However, its production is seriously affected by many biotic and abiotic constraints which could be overcame by concentrating the production on resistant or tolerant cultivars. In order to identify such cultivars that are known to exist in Benin traditional agriculture, 51 villages were randomly selected throughout the production zones and surveyed. Out of the 426 cultivars (subject to synonymy) evaluated using participatory approach and 13 agronomic, culinary, and technological traits, 25, 47, 49, 64 and 64 cultivars respectively tolerant to poor soils, nematodes, high soil moisture (adaptability to lowland), drought and chips (peeled and dried tuber) storage insects were, among others, identified. These pools of cultivars could serve in breeding program or be directly used in varietal exchanges towards the zones of interests. The agromorphological characterisation conducted per pool of performing cultivars revealed the existence of many duplicates that should be clarified with the use of molecular markers. Flowering, sex and intensity of flowering of the different cultivars were analysed and revealed a low rate (11.68 %) of non-floriferous plants, a high rate (61.03 %) of plants with low intensity of flowering and five types of male inflorescences indicating a hypothetical evolution towards the suppression of flowering with the cultivated yams.

Effect of Pretreatments on Color, Functional and Pasting Properties of White (Dioscorea rotundata) and Yellow Yam (Dioscorea cayenensis) Varieties

The effects of blanching, sulfiting and cooking pretreatments on color, functional and pasting characteristics of flours of Dioscorea rotundata (Abuja, Amula, Gbangi) and Dioscorea cayenensis (Alo) cultivars were investigated. The L* (71.45–79.98), a* (2.36–4.72), b* (19.96–25.71), ΔE (0–6.68), ΔC (0–5.75) and hue angle (78.99–84.77) varied significantly with pretreatment and yam variety. Also, loose (0.44–0.77 g/cm3) and packed (0.79–0.97 g/cm3) bulk densities, water (13.5–22.0%) and oil (10.0–19.0%) absorption capacities, and solubility (13.40–59.10%) and paste transparency (44.50–61.90%) varied with pretreatment and variety. Average peak viscosity of cooked and sulfited yams of Abuja, Amula, Gbangi and Alo was 19.58 and 16.96, 35.33 and 131.84, 92.18 and 79.00, and 61.88 and 163.92 rapid visco analyser, respectively. Peak, trough, breakdown and setback viscosities of pretreated yams were significantly lower than the untreated control. Flours of pretreated Alo and Gbangi varieties showed higher values of peak, trough, breakdown and setback viscosities than Amula and Abuja varieties. Practical Applications Huge postharvest losses are often recorded during handling and storage of yams as a result of the high moisture content, sprouting and activities of external agents, such as insects, rodents and moulds. However, drying of yams and the subsequent milling into flour has been found to increase the utilization and production of value-added yam flours that could easily be reconstituted and consumed or used as raw materials for further processing. The need to determine the effect of appropriate pretreatments prior to the drying of yams is germane to the production of high quality and acceptable flours for highly demanding consumer is necessary. The determination of physical, functional and physicochemical properties of flours of pretreated yams would be a pointer to the quality indices.