ABSTRACT

Chemical composition of some local spices and their antimicrobial activities in yam pepper soup stored at refrigeration temperature for 48 hours were studied. Three spices, M. myristica seeds, O. gratissimum leaves and Z. officinale roots  in their fresh and dried forms were used in the study. The proximate composition, mineral and vitamin contents as well as phytochemical screening and antioxidant activities of the spices were determined using standard analytical methods. Their antimicrobial activities in yam peppersoup stored in a refrigerator for 48 hours were also determined using standard microbiological techniques. For proximate composition such as ash, fat, fibre and mineral content such as k, Na, Ca,Mg,and P, the dried spices had the highest composition and were significantly (P<0.05) different from each other. The data obtained for vitamin C showed that fresh M. myristica (240.60 mg/100g) had the highest value and dried Z. officinale (1.33mg/100g) the least. For vitamin B₁ and_, B_2, no value was detected for all the dried spices and fresh O. grastissimum. Qualitative phytochemical screening showed that alkaloid was present in moderate concentration in the fresh and dried spices. Quantitatively, the concentration of the phytochemicals varied significantly in the different spices in their fresh and dried forms. The fresh spices had higher flavonoid (0.13-1.31%) and  saponin (0.15-0.74%). Antioxidant activity of the spices varied significantly with the fresh spices having better scavenging and chelating capacities than the dried spices. Z. officinale was observed to have a significantly higher (P<0.05) ferric-reducing antioxidant potential (FRAP) value (3.97mg/ml) in its dried state than in its fresh state (3.69mg/ml). There were significant variations in the microbial load of the spiced soup. The control soup (no spice) had the highest microbial load. No synergistic effect was recorded with the mixed spices. For sensory evaluation, on the overall acceptability level, the pepper soup prepared with O. gratissimum had the highest acceptability mean score of 8.05. The result of this study suggests that the spices can be exploited as natural antioxidants and antimicrobials in food- related systems.