Effects of extracts from three indigenous spices on the chemical stability of smoke-dried catfish ( Clarias lezera ) during storage

摘要

Fishes are the cheapest source of animal protein and it plays an important role in the diet of many people in both developed and developing countries. It is an important ingredient in the Nigerian traditional cuisine, cat fish being one of the most valued and very diverse groups of bony fish. The catfishes are a monophyletic group, belonging to the super-order called the Ostariophysi. Freshly caught fish spoil easily and therefore requires adequate preservation and storage. Of all flesh foods, fish isthe most susceptible to tissue decomposition, development of rancidity, and microbial spoilage. Fish begin to deteriorate as soon as they leave the water. The preservation of fish is therefore considered to be a major hindrance to its production and utilisation especially in the tropical countries in Africa. The four most popular methods of fish preservation are freezing, canning, smoking and pickling, the major preservation method being pickling or salting, which has been used for centuries. In this presentstudy, the effect of extracts from three indigenous spices; Piper guinensis (uziza), Xylopia aethiopicum (okada) and Myrustica monodora (ehuru) on the preservation of smoked-dried catfish stored for six weeks were evaluated using brine solution as control. Samples treated with uziza showed the lowest moisture content of 6.5% and lowest mean FFA formation of 0.55%, which was significantly different (p<0.5) fromthe other spices. The mean peroxide value range of 5.8-15.1 meq/kg was observed throughout the storage period for all the spices used. Thiobarbituric acid values ranged from 0.6mg/kg-1.4mg/kg with the lowest mean value of 0.37 mg/kg recorded in fish samples treated with uziza while the highest mean TBA value of 1.14mg was obtained in ehuru treated samples. This new research reveals that the three indigenous spices used, including Piper guinensis, Myristica monodora and Xylophiaaethiopicum had chemical preservative and antioxidant properties. Among the three spices, Piper guinensis (uziza) was found to have the most effective preservation potential of smoked-dried fish during storage. This new result is anticipated to provide a simple, cheaper, healthier and safer method of fish preservation in developing countries.