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Browsing by Author "Doni, Ermias Ali"

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  • Development of bio-tools and technology targeting Histamine monitoring in seafood products
    Publication . Doni, Ermias Ali; Guerreiro, Liliana I.T. dos Anjos; Power, Deborah
    Seafood is a vital source of nutrients but if contaminated, can cause foodborne illnesses such as scombroid fish poisoning caused by histamine (HIM), a major cause of food poisoning, particularly by spoiled seafoods like tuna. Accurate and reliable detection methods and strict compliance with regulatory limits are crucial to ensure food safety and to protect consumer health. Various methods exist for detecting histamine and other biogenic amines (BAs), including both direct and indirect approaches. The primary objective of this study was to develop and optimize an alternative method, specifically focusing on chromatography, microbiology, and molecular techniques, to monitor HIM and other relevant BAs in fish and fish products, with a particular emphasis on tuna. A GC-MS method was developed for the detection of histamine (HIM) and other biogenic amines (BAs), including putrescine (PUT) and cadaverine (CAD). Solid-liquid extraction followed by derivatization was employed, with optimal conditions for derivatization time and temperature determined using central composite design. This method achieved limits of detection (LOD) ranging from 11 to 36 mg/kg and limits of quantification (LOQ) from 33 to 110 mg/kg, with average recoveries between 54 % and 85 % in tuna fish samples. An Improved version of Niven's media was developed to broaden its applicability for various plating methods. This improved media successfully overcame medium hydrolysis problems and adhered to standard autoclave procedures. It demonstrated comparable effectiveness to reference media, such as Plate Count Agar (PCA) and Violet Red Bile Glucose Agar (VRBGA), when tested with a reference strain of Morganella morganii, showing no significant difference (p=0.92). Additionally, the improved Niven’s approach included reducing the agar concentration to 1 %, without modifying performance and significantly reduced costs. The GC-MS and microbiology methods were validated using bluefin tuna (Thunnus thynnus) samples contaminated with Morganella morganii and exposed to abusive temperature storage conditions. The methods produced consistent and reliable results, which were corroborated by 16S rRNA gene sequencing for species identification and hdc gene amplification for the identification of Histamine forming bacteria (HFB). These findings underscore the potential of the developed methods for effective monitoring of HIM and BAs in fish, thereby ensuring food safety and regulatory compliance and to safeguard consumer health.
    2024-09-16Master thesis Embargoed access Show more