Effects of Inorganic Fertilizer Application on the Quality and Sensory Attributes of White Yam ( <i>Dioscorea rotundata</i> ) Varieties

Abstract

Dioscorea rotundata yam is an economically important staple food and constitutes a significant proportion of the essential carbohydrate requirements of the people in West Africa. Over the years, the tuber crop has witnessed a significant increase in production, partly due to the application of inorganic fertilizer. This study, therefore, investigated the effects of these fertilization and nonfertilization treatments on two D. rotundata varieties, CRI–Pona and TDr15042016. Standard methods were employed in the determination of proximate, functional, pasting, and sensory characteristics of the yam varieties. Inorganic fertilization of the two varieties (CRI–Pona and TDr15042016) increased moisture (69.16% and 70.35%) and ash (1.41% for both varieties) contents, respectively. For the functional properties, bulk density (0.86 mg/mL for both varieties), swelling power (6.35% and 6.86%), and water absorption capacity (109.08 and 202.26) were increased with fertilization, respectively. The paired comparison test for taste showed a significant difference ( p &lt; 0.05) between fertilized and nonfertilized yam variety CRI–Pona but a nonsignificant difference for TDr15042016 variety. From the relative importance index, fertilized TDr15042016 and nonfertilized CRI–Pona were the most liked varieties, showing no significant difference in overall acceptability. A significant preference for fertilized TDr15042016 across multiple attributes in all sensory tests was noted. At the same time, nonfertilized CRI–Pona competed favorably in overall acceptability and the ranking of quality attributes. The desirable quality characteristics associated with inorganic fertilization could be useful for yam value chain actors and serve as a launchpad for further investigations into mechanisms resulting in such changes.