Effects of pre-treatment with extracts of Ocimum gratissimum and Vermonia amygdalina on proximate and organoleptic properties of processed Clarias gariepinus (Burchell, 1822)

Abstract

The study evaluated nutritional and organoleptic properties of Clarias gariepinus pre-treated with aqueous leave extracts of Ocimum gratissimum and Vernonia amygdalina before processing. Thirty-six (36) C. gariepinus (live weight = 1.2± 0.2kg) samples were procured and processed for the study. Fish samples were divided into three parts of twelve fish each. Each part was grouped into three treatments having four fish in each group using a completely randomized design. Treatment one (T₁) had fish immersed in 5% brine without herbal extract (control). In Treatment two (T₂), fish were soaked in mixture of 5% brine and 5% O. gratissium (scent leaf) extracts while Treatment three (T₃) had fish soaked in mixture of 5% brine and 5% V. amygdalina (bitter leaf) extracts all for 30 minutes. Treated fish samples were smoke-dried using charcoal kiln for 5 hours at temperature of 80 – 90° C. Samples were then cooled under ambient condition (30+3^oC) for 4 hours. The smoke-dried fish samples were labeled according to treatments and stored for 7 days under aseptic condition. Organoleptic properties of the samples were conducted at every 24-hour of storage using a 9-point hedonic scale. Mean values of proximate composition of samples were significantly different (p<0.05). Protein content (70.01%) in T₃ was higher than 68.31% and 66.62% in T₂ and T₁ respectively. Similarly, fat (5.12%) and ash (4.68%) levels for T₃ were higher than 4.85% and 4.46% fat with 4.36% and 3.98% ash contents for T₂ and T₁ respectively. Results of mean scores for each organoleptic property decreased significantly (p<0.05) during storage period with no consistent trend in score pattern.

Keywords: Clarias gariepinus, extract pretreatment, Ocimum gratissimum, organoleptic, Vernonia amygdalina.