Abstracto

Microbial analysis of selected natural preservatives on shelf life and safety of smoked tilapia fish (Oreochromis niloticus)

Tairu HM, Adedokun MA, Adelodun OB and BadmusBD

Fish has played an important role in nutrition, profitability and livelihood security of people in many developing countries. This work was carried out to study the microbial screening of some selected natural preservatives on the shelf life and safety of smoked tilapia fish (Oreochromis niloticus). The microbial load counts (TVC, TCC and TFC cfu/g) of microorganisms, sensory evaluation, proximate composition and isolated microorganism were evaluated in smoked tilapia fish preserved for 0, 2, 4, 6 and 8 weeks with 5 g of salt, ginger, garlic, cloves (natural preservatives) and a sample without preservatives. The salt sample recorded the highest total viable count (TVC) of 3.5 × 105 and zero or no growth was recorded in the ginger, clove and garlic sample at the end of 8 weeks of storage, while after 6 weeks of storage, the sample without preservatives spoiled. The highest fungal count (TFC) of 4.4 × 105 was recorded in clove sample and zero or no growth was recorded in salt, ginger and garlic sample while unpreserved sample spoiled after 4 weeks of storage. At the end of 8 weeks of storage, total coliform count (TCC) of all samples recorded zero or no growth except unpreserved sample which spoiled after 6 weeks of storage and the microorganism isolated from the samples exhibited that the highest number of microorganism species was shown in untreated sample with 6 species of microbes and the lowest was in garlic with 3 species of microbes. The highest value (64.75%) of crude protein in proximate composition was recorded in ginger sample while the lowest was 20.32% in unpreserved sample. The results of sensory evaluation show that all samples were generally accepted by consumers except unpreserved sample. Statistical analysis showed a significant difference in the number of colonies formed between the groups (p < 0.05). All the preservative samples used in this work reduced the microbial load, prevented rapid spoilage and promoted a longer shelf life of smoked tilapia. These natural preservatives are medicinal, have no side effects and add to the flavour and seasoning of some foods, and also act as antimicrobial agents by killing microbes present in the food.