Physicochemical and bioactive properties of selected white yam (Dioscorea rotundata) varieties adapted to riverine areas of Nigeria

Abstract

Yam (Dioscorea spp.) is a major food of cultural, economic and nutritional importance in Nigeria and throughout West Africa. In this sub-region, white yam (Dioscorea rotundata) is the most dominant and important species. This study is aimed at characterizing high yielding yam varieties of this species adapted to riverine areas and forest zones of Nigeria for physical and chemical characteristics. Eleven yam varieties collected from local farmers in the South-southern part of Nigeria were evaluated for their physicochemical characteristics, bioactive compounds (vitamin C, phytic acid and tannin), functional and pasting properties. Results indicated that there were significant varietal differences (P<0.05) among the parameters evaluated. The moisture contents of the investigated varieties ranged from 59.5 to 68.8%, ash content ranged from 1.39 to 2.93%, protein content from 1.96 to 4.90%, fat content from 0.356 to 3.39%, total free sugars from 1.05 to 7.02% and total starch from 33.9 to 75.7%. The bioactive content results show that vitamin C content ranged from 5.64 mg/100 g to 6.99 mg/100 g, phytate from 1.12 to 2.37% and tannin from 0.359 to 1.18 mg/g. The pasting properties results show that peak viscosity ranged from 215 to 470 RVU, trough viscosity from 198 to 385 RVU, breakdown viscosity from 8.71 to 84.5 RVU, final viscosity from 278 to 571 RVU, setback viscosity from 66.2 to 204 RVU; peak time ranged from 4.97 to 7.0 min and the pasting temperature from 61.7 to 62.6°C. This study shows that the physical and chemical characteristics of these high yield yam varieties were similar to those reported for most yam varieties in other parts of Nigeria and has a great potential as source of bioactive compounds and protein.

Calibration development for nutritional evaluation of Yam (Dioscorea sp.) using Near-Infrared Reflectance Spectrophotometry (NIRS)

“…However, these results are consistent with PolyCarp, Afokwa, Budu, and Otoo (2012) who reported <1.0% for fat and 4.0-6.5% for protein. However, amylose content ranged from 18.8% to 44.41% with an average value of 32.84% and in agreement with what was reported in the literature, ranged from 24.3% to 38.1% (PolyCarp et al, 2012;Alamu et al, 2014;Eke-Ejiofor & Owuno, 2012 Maziya-Dixon and Asiedu (2003) and 33.9-75.7% reported by Alamu et al (2014). The bioactive content of the yam samples shows that phytic acid and tannin had a mean ± SD of 1.17 ± 0.42 mg/ g and 2.04 ± 1.93 mg/g, respectively.…”

“…The bioactive content of the yam samples shows that phytic acid and tannin had a mean ± SD of 1.17 ± 0.42 mg/ g and 2.04 ± 1.93 mg/g, respectively. The mean and standard deviation of phytic acid (2.16 ± 0.44%) obtained was higher than what was reported (1.82 ± 0.4%) by Alamu et al (2014) for yam varieties from riverine areas, using chemical methods (Alamu et al, 2014). The difference could be due to genetic and environmental differences.…”

“…Three tubers of varying sizes-big, medium, and small-were selected for each variety by simple randomization from a bulk of freshly harvested tubers. The Harvest Plus sampling protocol for cassava as reported by Alamu, Maziya-Dixon, Okonkwo, and Asiedu (2014) was adapted for the yam tubers. The tubers were washed, air-dried, peeled, and again washed and dried with soft paper.…”

Potential of Neglected and Underutilized Yams (Dioscorea spp.) for Improving Nutritional Security and Health Benefits

“…essential oils have various pharmacological activities (Alamu et al, 2014). The Dioscorea species are known to contain a good quantity of bioactive compounds such as phenols, alkaloids, tannins, flavonoids, saponins, glycoside steroids, anthraquinones, etc.…”

Factors Influencing the Agronomic Performance of the Adapted Yam Minisett Technique in Nigeria – Planting Date and Gender of the Farmer

“…This paper focusses on D. rotundata (white yam) and henceforth will be referred to as ‘yam’. The yam tuber is rich in carbohydrate (75 to 85% of dry weight) and provides an excellent source of the B-complex group of vitamins, vitamin-A, beta carotene and some minerals (Muzac-Tucker et al ., 1993) and the protein content varies between 2 and 5% on a dry weight basis (Alamu et al ., 2014). As a result, it is thought that yam tubers provide excellent nutritional sustenance (Muzac-Tucker et al ., 1993) and can be sold as a cash crop given its relatively high market price.…”