Physicochemical Properties of Selected Local Medicinal Soups Consumed in Southwest Nigeria

Abstract

Cottonseed (Gossypium herbaceum), bitter leaf (Vernonia) amydalina), cashew leaf (Anacardium occidentale), Piper nigrum (black pepper) and scent leaf (Ocimumgratissimum) are major ingredients used in preparation of the local soups namely; ‘koroowu soup’, ‘black soup’, ‘cashew leaf soup’ and ‘ewe luje soup’ consumed in certain parts of Nigeria. The ingredients for the soups were sorted according to the local preparations, separately blended into a paste and were either cooked or uncooked. The pastes were subjected to physicochemical (proximate, pH, total titratable acidity, mineral, phytochemical, antioxidant) and antimicrobial assays. The results showed that the cooked and uncooked pastes from these soups had pH ranged from 4.38-5.89, total titratable acidity (TTA) (0.05%-0.37%), moisture (9.30%-24.75%) and ash content (3.41%-7.17%). However, it was observed that the soup pastes were high in protein (10.39%-12.64%), fibre (13.82%-20.48%) and fat (21.11%-34.47%). The mineral content of the soups revealed that calcium ranged from 1.24ppm8.74 ppm, zinc (1.3 ppm-1.65 ppm), potassium (4.04 ppm-20.94 ppm) and sodium content (14.27 ppm-67.00 ppm). The phytochemical composition of the pastes showed that saponin (4.59mg/g-62.91 mg/g) was the highest, followed by phytate (15.24 mg/g-61.39 mg/g), alkaloid (0mg/g-27.84 mg/g), tannin (2.39 mg/g-6.57 mg/g), oxalate (0.72 mg/g-2.12 mg/g). The soup samples were found to exhibit free radical scavenging property (DPPH) of 30.0%-100%, 2,2’-azino-bis(3-methylbenzothiazoline-6-sulphonic acid) (ABTS) scavenging ability (70.0-100%), and ferric reducing power (2.73 mg/g-20 mg/g). However, the aqueous extract from the soup pastes could not inhibit the growth of microorganism tested. Further studies should be carried out to identify the bioactive compounds responsible for the antioxidant activities recorded from the soup pastes.