Evaluation of Moringa and Lavandula extracts as natural antioxidants in tilapia fish burger

Inspection of Capparis spinosa essential oils for quality assurance of fish burgers during refrigerated storage

Fish products are highly perishable as a result of easy spoilage by microorganism populations. The aim of this study is to evaluate the effects of Capparis spinosa essential oils (CSEOs) on physicochemical, sensory, oxidative, and microbiological attributes for fish burgers during refrigerated storage (8 days). For this purpose, CSEOs were prepared by water distillation (CS-WD), CO2 supercritical fluid (CS-SCF), subcritical water (CS-SW) to determine bioactive substances. Total phenol and flavonoid contents and also antioxidant activity were measured in CSEOs extracted by these procedures and phytochemical identification was performed through gas chromatography and mass spectroscopy. These essential oils (EOs) were used at 0.2% in fish burgers, and controls (without additives) and those containing sodium erythorbate were also prepared. Physicochemical, oxidative, microbiological, and sensory functions were examined every 2 days. Phytochemicals were found in CSEOs, and the highest was related to isopropyl isothiocyanate. Addition of CSEOs led to dark, yellow and red colors for fish burgers compared with control. The manufacture of primary and secondary products in oxidation and different microorganisms in samples were significantly decreased by CSEOs compared with controls (p < .05). The antioxidant feature of the burger with CS-SCF was higher than that of the sample treated with CS-WD, but these EOs indicated almost the same antimicrobial attributes, and the lowest antioxidant and microbial activities were found for CS-SW in the fish burger. The sensory results demonstrated that CSEOs did not reduce scores, which maintained the acceptance quality of burgers during refrigerated storage. As a conclusion, CSEOs can be used as effective antioxidants and preservatives in burgers, and sensory acceptance was preserved during storage.

Assessment of a Diterpene-Rich Rosemary (Rosmarinus officinalis L.) Extract as a Natural Antioxidant for Salmon Pâté Formulated with Linseed

The use of natural plant extracts with standardised antioxidant properties is a growing strategy to stabilise food products. The use of a rosemary lipophilic extract (RLE), obtained from the by-product of high-yield selected plants and rich in polyphenols (334 mg/g, with diterpenes such as carnosic acid and carnosol as main compounds), is here proposed. Four RLE doses (0, 0.21, 0.42 and 0.63 g/kg) were tested in a salmon pâté formulated with sunflower oil and linseed, which was pasteurised (70 °C for 30 min) and subjected to storage at 4 °C and 600 lux for 42 days. Rosemary diterpenes resisted pasteurisation without degrading and showed antioxidant activities during the shelf-life of pasteurised pâté. RLE addition led to increased peroxide value (from 3.9 to 5.4 meq O_2/kg), but inhibited formation of secondary oxidised lipids such as malondialdehyde (from 1.55 to 0.89 mg/g) and cholesterol oxidation products (from 286 to 102 µg/100 g) and avoided discolouration (slight brownness) in the refrigerated pâté. However, this did not entail relevant changes in fatty acid content or in the abundance of volatile organic compounds from oxidised lipids. Increasing the RLE dose only improved its antioxidant efficacy for some oxidation indexes. Thus, the oxidative deterioration of these types of fish emulsion can be naturally controlled with rosemary extracts rich in diterpenes.