Nutritional value and safety of air potato Dioscorea bulbifera L. fermented with Pleurotus ostreatus and Calocybe indica

Abstract

The proximate, minerals, antinutrient and amino acid contents of the unfermented air potato (UAP), fermented air potato (APF), fermented air potato with Pleurotus ostreatus (APP) and fermented air potato with Calocybe indica (APC) were carried out using standard methods. The biosafety of the samples was also determined using Wistar rats. APP has the highest crude fiber (11.61%) and protein content (20.44%). APF has the highest moisture content of 12.95%, while UAP has the highest carbohydrate content of 71.46%. The mineral composition (mg/g) of samples revealed that APP has the highest Zn (1.21), Fe (7.53) and Mn (0.78%). APC has the highest Ca (71.31%), Mg (4.76) and K (60.65), while APF has the highest Cu (1.72%), Ni (0.38%), Cr (0.65%), Cd (0.29) and Pb (25.16). Unfermented air potato (UAP) contains the highest amount of phenols, tannin and saponin with the values of 1.16 mg/g, 2.50 mg/g and 2.57 mg/g, respectively. APP has the highest flavonoid (2.77 mg/g) and alkaloids (3.05 mg/g) and significantly different (p < 0.05) from other samples. Essential and non-essential amino acid detected in unfermented and fermented air potato ranged from 0.70 to 10.81 mg/g. Hematological and histopathological studies revealed no adverse effect on the blood and organs of the rats. The fungal mycelia enhanced the nutritional contents of fermented air potato. Hence, bioactive compounds in air potato can be of exploited and supplemented into food products.