Effects of cultivar and agrobotanical storage treatment on organolepetic quality of yam ( Dioscorea rotundata )

摘要

There is current interest in the search and use of agrobotanicals in preference to conventional chemicals in agriculture as plant protectants hence the need to investigate the potential effects of some of the agrobotanicals on yam food after storage. This study was, therefore, conducted to assess the effects of yam cultivar and agrobotanical extracts on the organoleptic quality and acceptability of two yam based food forms: boiled yam and pounded yam. Tubers of four yam cultivars (Nwaopoko, Danacha, Ezakwukpolo and Pepa) were treated with aqueous leaf extracts of Neem ( Azadiracta indica ), Scent leaf ( Occimum gratissimum ), pod extracts of ‘Uda’ ( Xylopia aethiopica ), root extracts of Ginger ( Zingibger officinale ) and a synthetic phytohomorne (Gibberellic acid) and stored for six months. Thereafter, two food forms (boiled yam and pounded yam) were prepared from the stored yam tubers and a nine-member panel of judges enlisted to perform sensory quality assessment on them. The attributes scored with respect to boiled yam were colour, taste, texture, mealiness and general acceptability while pounded yam was assessed for its aroma, texture, colour and general acceptability. No significant differences were found among the sensory attributes due to the agrobotanical treatments rather, differences were due to yam cultivars. The results obtained and confirmed by the scatter plots and multiple linear regression showed that texture and taste contributed much to the general acceptability of boiled yam while aroma and consistency were the major qualities of pounded yam. Consistency of pounded yam was best with Nwaopoko and Danacha cultivars but significantly less so with other cultivars with or without agrobotanical treatment. The agrobotanical treatments did not affect the culinary quality of the stored yam tubers as no evidence of such treatment was noticed in the prepared yam foods. This result suggests that the constituent active ingredients imparted on the tubers during storage by the plant extracts were either water-soluble and heat labile or that their shelf lives were less than six months of the storage period and therefore had no effects on the quality attributes of food yams.