Effects of thyme (Thymus vulgaris) and cinnamon (Cinnamomum zeylanicum) on the microbial load of smoke dried European hake fish (Merluccius spp) stored under ambient temperature

Abstract

This study was carried out to determine the effect of Thyme marinade (sample B), Cinnamon marinade (sample C) and a combination of both spices (sample D) on the microbial load of stored smoked-dried Merluccius sp. Comparative analysis of the microbial load of each  treated fish samples  during ambient storage was done biweekly for six (6) weeks and then  samples of each treatment were taken to the  laboratory periodically. Sample  A was the control, smoke dried fish without any treatment. The fish samples  were analysed using Potato  Dextrose Agar and Nutrient Agar for fungi and  bacteria respectively. The initial microbial load before storage showed that  the highest  number of bacteria counts occurred in smoke-dried Merluccius sp. Sample A (control) had the highest (2.8×10³ ) bacterial load while the  lowest was in smoke-dried Merluccius sp. treated with cinnamon only  (sample C, 1.8×10³ ). The highest fungi count was in sample B  (thyme)  7.5×10² and lowest fungi count was in sample D (thyme and cinnamon)  2.4×10². After six weeks, sample B (thyme) had the  highest fungi count  2.6×10⁴ while sample D (thyme and cinnamon) had the lowest fungi count  9.6×10³. Prevention of spoilage due to  microbiological, enzymatic, or  chemical changes, and shelf-life extension of fish are typically carried out  with the recommended useful  chemical preservatives, such as sodium  benzoates, sodium nitrite, and sulfur dioxide, on the other hand accumulation  of these artificial  preservatives in tissues can be hazardous to human health.  Storage of fish without natural or artificial preservatives would ultimately  lead to quicker spoilage, thereby leading to financial losses to fish  processors and marketers. Use of natural preservatives such as thyme  and  cinnamon would help to prevent theses hazards to human health and losses  caused due to spoilage during storage.