Study of the effects of the dosage of extracts of Thymus vulgaris (Thyme) and Salvia rosmarinus (Rosemary) on the quality (organoleptic, chemical and microbiological) of smoked Clarias gariepinus

Abstract

In Senegal, smoking and drying are the most common methods of preserving catfish. However, the quality of the products and their ability to preserve them are still a recurring problem because of post-treatment contamination and the favourable climate that facilitates their deterioration. Thus, the present study aims to evaluate the effect of different concentrations of medicinal plant extracts such as Thymus vulgaris and Salvia rosmarinus during the smoking process on the organoleptic, chemical and microbiological properties of smoked catfish. The results of the sensory evaluation showed that the samples with the plant extracts, especially those containing 2% Salvia rosmarinus and 2% Thymus vulgaris, obtained better scores for the criteria of color, texture, taste and aroma compared to the other samples. The results of the chemical analysis showed satisfactory concentrations of Total Volatile Basic Nitrogen (TVBN), with levels below the standards of the Senegalese Association for Standardization (ASN), indicating good chemical quality of the products. The absence of particularly toxic PAHs such as benzo(a)pyrene, a carcinogenic compound potentially formed during the smoking process, is noted. Samples treated with the plant extracts showed a reduction in the concentrations of certain PAHs compared to the control samples, suggesting that the use of these plants could reduce the formation of these compounds that are harmful to the health of consumers. Microbiological testing revealed the absence of dangerous pathogens such as E. coli, Salmonella, and Staphylococcus coagulase in all samples. However, Total Aerobic Mesophilic Flora (TAMF), yeasts and molds were detected in some samples, with higher concentrations in the control compared to the treated samples, suggesting better management of microbiological quality in products treated with plant extracts.

Keywords: Clarias gariepinus, extracts, Salvia rosmarinus, Thymus vulgaris, smoking, quality.

DOI: 10.7176/FSQM/125-04

Publication date: May 30th 2025