Physico-chemical characterisation of yam (Dioscorea alata L.) tubers from Vanuatu

Abstract

The objectives of this study were: (1) to analyse the physico-chemical characteristics of 48 Dioscorea alata varieties representing a core sample of the Vanuatu national germplasm collection; (2) to relate those characteristics with the varieties eating quality; and (3) to assess the possibility of selecting varieties according to their chemotype. Overall, 331 accessions were collected from 15 different islands of Vanuatu, planted in an ex situ germplasm collection and described during 3 years. The 48 varieties included in the core sample were selected according to their island of origin, eating quality, tuber shape, tuber flesh colour and morphotype. Analyses of their tubers were made for percentage dry matter, starch, amylose, lipids, minerals, proteins, sugars and gelatinisation temperature range. Significant variation exists for each of these characteristics except for gelatinisation temperature. Varieties with good eating quality are characterised with high dry matter, starch and amylose contents. Chemotypes appear to be genetically controlled and further screening of germplasm and/or breeding will have to take into consideration these characteristics, important for farmers' adoption.

Application of near infrared reflectance spectroscopy for the evaluation of yam (Dioscorea alata) germplasm and breeding lines

“…Interestingly, species appreciated and suitable for daily consumption and for laplap , such as D. alata , D. cayenensis‐rotundata , D. nummularia and D. transversa , present low total sugars values (respectively, 1.79, 1.87, 1.63, 1.43%). These results confirm previous work suggesting that varieties with good eating quality are characterised by a high starch content …”

“…Likewise, species such as D. esculenta , which has a very high yield potential but is unsuitable for fufu . A preliminary study conducted on D. alata indicates that varieties with good eating quality and suitable for the Melanesian laplap (similar to fufu ) are characterised by high contents of dry matter and starch . In contrast, preferences for daily consumption of boiled or roasted tubers are linked to average starch content .…”

Dioscorea

“…The passport or characterization data of most of the accessions are also incomplete and duplicates are yet to be eliminated. Yam germplasm has been characterized for morphological characters (Dansi et al 1998(Dansi et al , 1999(Dansi et al , 2000a, physico-chemical characteristics (Lebot et al 2006), organoleptic properties (Egesi et al 2003), soluble tuber protein profiles (Ikediobi and Igboanusi 1983), or isozyme patterns (Lebot et al 1998;Dansi et al 2000a;Mignouna et al 2002a). Similarly, use of molecular markers such as amplified fragment length polymorphism (AFLP), RAPD and simple sequence repeat (SSR) markers have also been reported Malapa et al 2005;Egesi et al 2006;Scarcelli et al 2006;Tamiru et al 2007;Tostain et al 2007) in diversity studies of yams.…”

Functional effects of dried okra powder on reconstituted dried yam flake and sensory properties of ojojo—a fried yam (Dioscorea alata L.) snack

“…The tubers of D. alata are white, brown or brownish red in colour (Lebot et al 2005). The culinary and palatability properties of D. alata varieties vary significantly while some cook much faster than others.…”

“…This rapid colour change is attributed to the oxidation of polyphenolic compounds in the flesh thereby turning its colour to yellowish or brown (Osagie and Opoku 1984;Almentros and Del Rosatio 1985). Polyphenolic oxidation is also associated with off-flavours, bitterness and deserves in some cases, special preparation (Lebot et al 2005). This phenomenon is more predominant in D. alata than other Dioscorea sp.…”