Abstract

In this study, the effect of salting on the pH, phytochemicals, fungal flora and nutrient composition of Vernonia amygdalina leaves was investigated. There was a decrease in pH from 5.88 for the fresh, to 5.80, 5.73, 5.24, and 5.02 for the light brined, light salted, heavy salted and light brine + vinegar treated leaves, respectively. Leaves treated with water alone had a pH of 6.63. Compared with the fresh leaves, there was a decrease in all the nutrients investigated, except for sodium and calcium which increased significantly. The fresh sample showed the highest concentration of total phenolic compounds (TPC). Compared with the fresh, the highest loss of TPC was for the light brine + vinegar preserved leaves (51.69%) and the lowest loss was for the water treated (27.28%). The heavy salted and light salted leaves lost about a third (36.05 and 33.42%, respectively) and the light brined 45.93% of their TPC. In terms of organoleptic properties, reduction in fungal count and genera, and loss of moisture, heavy salting appears to be the most effective preservation treatment. These, coupled with only moderate loss of nutrients and phytochemicals is recommended as an effective technique for the preservation of V. amygdalina leaves. Screening of the fresh and treated produce indicated the presence of aflatoxin.

Key words: Vernonia amygdalina leaves, salting, nutrients, phytochemicals, fungal flora, aflatoxin.