Abstract
Red Tilapia is one of the most consumed but perishable fish in the world. As a result, it requires preservation methods for safe consumption without affecting its organoleptic characteristics. Chitosan encapsulating essential oils have shown to be an excellent food conservation method. For that reason, we carried out the study of the protective effect on red Tilapia fillets with chitosan beads (CB) incorporated with Thymus capitatus (TCEO) essential oil at 500, 1000, and 2000 mg/L to assess the conservation of the fillets. The TCEO composition was characterized by gas chromatography-mass spectrometry (CG-MS). For the other side, CB was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction spectroscopy (XRD), thermogravimetric analysis (TGA), and Scanning electron microscopy (SEM). The protective effect of the beads was tested against the Gram-positive and Gram-negative bacteria growth for four weeks. The results showed an inhibition effect in Gram-positive bacteria at higher TCEO concentration (1000 and 2000 mg/L). Besides that, the pH, total volatile basic nitrogen (T-BNV-N), color, and fillet texture were evaluated as quality attributes. The results suggested that the incorporation of the CB-TCEO allowed a higher contact of the active compounds with the food surface, which reflected more excellent stability. The quality attributes of the fillets were preserved for 26 days, suggesting its uses for the treatment for perishable food.
Highlights
According to the Food and Agriculture Organization (FAO) [1,2], in 2018, the world fish production reached a total output of 171 million tons per year
The main components of the TCEO identified by coupled gas chromatography-mass spectrometry (GC-MS) analysis [16], corresponding to 25 compounds, where 22 are monoterpenes (97.5%), two sesquiterpenes (2.4%), and as a significant component, carvacrol, which is considered to be a potent antibacterial [16]
In the chitosan beads (CB)-TCEO spectrum there is no evidence of an apparent shift or increase in the bands of the X-ray diffraction spectroscopy (XRD) [24], the one placed at 20◦ caused by the allomorphic tendon of the chitosan structure
Summary
According to the Food and Agriculture Organization (FAO) [1,2], in 2018, the world fish production reached a total output of 171 million tons per year. Some coatings work synergistically with antimicrobial agents such as extracts and essential oils which delays microbial deterioration, maintaining freshness and color, thereby showing great potential for application in the conservation of food products such as fish fillets [11,12]. Essential oils such as oregano (Origanum vulgare) and thyme (Thymus vulgaris), due to their complex mixture of components, have shown excellent activity against a great variety of microorganisms [13]. If these oils are colloidally protected, they achieve an exciting technology that is used in the food industry, as they prevent food volatilization and extends the fish’s useful life [14]. For the best of our knowledge, it is the first-time using chitosan beads incorporating essential oil of Thymus capitatus in Oreochromis mossambicus (red Tilapia) fillets under refrigeration conditions
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