Histamine Assay Kit

Fermented seafood paste, terasi, is a ubiquitous ingredient in Indonesian traditional cuisine. It is commonly used as a flavor enhancer due to its unique, strong, and complex flavor. Traditionally, terasi is made using planktonic shrimp (Acetes indicus) but some regional varieties of terasi include other seafoods, such as fish in their recipes. The present study aimed to explore the cultural and ethnic significance of terasi, investigating the current traditional preparation of terasi, and analyze the characteristics of terasi made from shrimp and fish. The traditional practice of terasi making in Cirebon, its birthplace, often includes the use of anchovy (Engraulidae) as an additional ingredient besides shrimp, as observed among more than 70% of local producers. Therefore, we characterized several aspects of terasi made from shrimp and anchovy (fish) under different proportions. Higher proportion of fish in terasi was associated with darker color due to browning reactions and higher microbial load, particularly proteolytic and lactic acid bacteria. Nutritionally, higher proportion of fish increased the protein content of terasi but decreased its fat content. A series of chemical analyses revealed that the addition of fish in terasi significantly increased protein hydrolysis, lipid peroxidation, and non-enzymatic browning (Maillard) reaction, thus resulting in a significant formation of toxic compounds such as histamine and acrylamide. Interestingly, organoleptic analysis showed that terasi made from an equal proportion of shrimp and fish was preferred by the panelists. Therefore, this study suggested that mixing shrimp and fish could be used as a strategy to increase consumer’s acceptance toward terasi. However, for food safety reasons, some adjustments in the fermentation period should be made in future studies since the addition of fish in terasi would increase microbial activity and accelerate chemical reactions.

Hákarl is a fermented fish traditionally produced in Iceland. In the present study, no scientific research has so far discussed the implication of histamine in this food. The first quantification of histamine in ready-to-eat samples of hákarl has been performed. The presence of the hdcA gene of Gram-positive bacteria, directly detected in the food matrix via qPCR, was also assessed. Histamine content was between 8.3 ± 0.8 and 13.2 ± 0.3 mg/Kg, with an overall mean of 10.6 ± 2.0 mg/Kg. Interestingly, the copy number of the hdcA gene carried by Gram-positive bacteria harbored by hákarl was below the detection limit in all the samples. Therefore, although the involvement of such a bacterial group cannot be excluded, the results suggest that the low histamine levels detected in the samples can presumably be associated with the decarboxylase activity of Gram-negative bacteria. The present study represents a step forward in understanding the microbiology of hákarl, although further investigations dealing with the monitoring of both histamine levels and microbiota dynamics during the production process are needed.