Spoilage Investigation of Chill Stored Meagre (Argyrosomus regius) Using Modern Microbiological and Analytical Techniques

Spoilage status of whole and filleted chill-stored meagre caught in January and July was evaluated using sensory, microbiological, 16S metabarcoding and Volatile Organic Compounds (VOCs) analysis. Based on the sensory analysis, shelf-life was 15 and 12 days for the whole fish taken in January and July, respectively, while 7 days for fish fillets of both months. For the whole fish, Total Viable Counts (TVC) at the beginning of storage was 2.90 and 4.73 log cfu/g for fish caught in January and July respectively, while it was found about 3 log cfu/g in fish fillets of both months. The 16S metabarcoding analysis showed different profiles between the two seasons throughout the storage. Pseudomonas (47%) and Psychrobacter (42.5%) dominated in whole meagre of January, while Pseudomonas (66.6%) and Shewanella (10.5%) dominated in fish of July, at the end of shelf-life. Regarding the fillets, Pseudomonas clearly dominated at the end of shelf-life for both months. The volatile profile of meagre was predominated by alcohols and carbonyl compounds. After univariate and multivariate testing, we observed one group of compounds (trimethylamine, 3-methylbutanoic acid, 3-methyl-1-butanol) positively correlating with time of storage and another group with a declining trend (such as heptanal and octanal). Furthermore, the volatile profile seemed to be affected by the fish culturing season. Our findings provide insights into the spoilage mechanism and give information that helps stakeholders to supply meagre products of a high-quality level in national and international commerce.

Prospects for using extractive oils of spicy-aromatic raw materials in the technology of formed semi-finished products

To improve public health, it is necessary to produce products that include natural ingredients with antioxidant properties. In foreign and domestic practice, there is a significant number of multifunctional additives of plant origin, which combine the ability to improve the antioxidant and flavoring properties of finished products. The development of the technology of meat and fish formed semi-finished products of the Ayurvedic direction is relevant today. The main raw materials for the production of batches of meat and fish formed were poultry meat, sea fish – hake, pollock, ocean saithe, haddock, which have the greatest amount of protein. As a result of a comparison of the chemical composition of fish and meat raw materials, organoleptic studies, it was found that the most optimal ratio was the samples in which chicken fillets and ocean fish fillets – haddock were used in a ratio of 50 : 50 %; pollock – In a ratio of 60 : 40 %. To extend the shelf life of the developed meat and fish formed, we have chosen extractive cardamom oils and a mixture of rosemary and thyme. Four variants of formulations were developed with the addition of extractive oils of cardamom and a mixture of rosemary and thyme in the amount of 2, 3, 5 and 8 % to the mass of raw minced meat. As a result of organoleptic studies, a comparative analysis of the average ratings of each sample using different amounts of fish raw materials, it was found that among the additives presented, the best is a mixture of extractive oils of rosemary and thyme with, namely, a sample of meat and fish formed semi-finished products using haddock fish fillets and a sample in the composition which includes pollock fillet with a blend of rosemary and thyme extractive oils. Also, microbiological studies of samples of meat and fish formed were carried out with the addition of a mixture of extractive oils of rosemary and thyme. Based on the results of microbiological studies, the safety and quality of the developed products have been confirmed.

Improving the Quality of Frozen Fillets of Semi-Dried Gourami Fish (Trichogaster pectoralis) by Using Sorbitol and Citric Acid

Semi-dried gourami fish (Trichogaster pectoralis) is popularly consumed domestically and exported as a frozen product. This study was conducted to prevent deterioration quality in frozen fish fillets during storage. This research aims to investigate the effects of sorbitol and citric acid at concentrations of 2.5% and 5% (w/w) of frozen gourami fish fillets compared to the fillets soaked in distilled water on physicochemical properties, such as cooking loss, cooking yield, drip loss, pH, TBARS, color, and texture profile analyses (TPA) during storage at −18 ± 2 °C for a period of 0, 20, and 40 days. The fish soaked in sorbitol and citric acid solutions had significantly (p < 0.05) higher protein and fat contents than the control sample. Sorbitol was able to retain moisture in the product; therefore, the drip loss and cooking loss were the lowest, and cooking yield was the highest among other samples (p < 0.05). The addition of 5% (w/v) citric acid in frozen fish fillets can significantly retard the thiobarbituric acid reactive substance (TBARS) (p < 0.05) during storage when compared to fish soaked in sorbitol solution kept for the same period. However, the addition of citric acid resulted in low quality in texture and color of frozen fish fillets. The use of sorbitol was the best alternative in frozen fish fillet product due to reducing the negative effects of freezing quality of the products and generating a cryoprotective effect compared to the fillets soaked in distilled water.

Characterization of tannin based colorimetric indicator and its application on fish packaging

This study aims to determine characteristics of the gel-type colorimetric indicator at various pH and under different storage conditions, then determine the indicator characteristic in the packaging of fish fillets during storage. The gel-type color indicator was synthesized with a concentration of 1%, 3%, and 5% gambir powder. The FT-IR spectra of the color indicator showed the presence of tannin functional groups, namely C=C aromatic rings, C-C phenolic, and C-H groups, respectively at wavenumbers 1517-1519, 1440-1475, and 752-761 1/cm. Moreover, the coefficient value of the Red-Green-Blue (RGB) of the indicator was changed over pH and did not appear to be consistent. Based on the Analysis of Variance (ANOVA) test, the concentration of gambir powder and duration of color indicator storage, respectively, had a significant effect (P <0.05) on the value of the RGB coefficient. The color indicator exposed to sunlight had a smaller RGB coefficient value than the RGB coefficient value of the indicator stored at room temperature and 5-7°C. The application of color indicators with a 1% Gambir powder concentration in fish fillet storage has been tested for 5 days at a temperature of 5-7°C. They showed that the RGB coefficient value of the indicator was proportional to changes in the pH value of fish fillets but not in line with changes in Total Volatile Based Nitrogen (TVBN) of fish fillets.

EFFECTIVENESS OF SOLAR THERMOELECTRIC COOLER FOR FISH PRESERVATION: EXPERIMENTAL STUDY ON QUALITY CHARACTERISTICS OF Pangasius bocourti FISH FILLETS DURING STORAGE

Preservation of fish products is a big issue where inconsistent electricity supply. In the current study, a solar thermoelectric cooler (STC) was fabricated by exploiting the solar energy and its cooling potential for fish preservation was evaluated. The STC consists of a photovoltaic (PV) panel, battery, PV charge controller, thermoelectric cooling system, and cooler box. The temperature of the STC decreased to 7.4ºC within 90 minutes and then reached 5±0.2ºC in 150 min. The cooling capacity and coefficient of performance of the STC were 23.8 W and 0.44, respectively, at an input electric current of 3.5 A. The Pangasius bocourti fish fillets were stored in the STC for 10 days and tested its quality at 2 days intervals. On day 10, thiobarbituric acid, peroxide, pH, water binding ability, total plate count values were 1.65mg MDA/kg, 5.04 mEqO2/kg, 7.16, 26.18%, and 4.26 log CFU/g, respectively. A significant reduction in hardness, springiness, and chewiness values was observed, whereas no cohesiveness changes. The color values L* and a* decreased significantly, whereas b* and ΔE increased. The sensory attributes were found in the range of 5.2-6.0 on the 10th day. As the quality parameters showing an acceptable level, STC could be an alternate green option for fish preservation.

Development and evaluation of low-fat ready-made dishes prepared by the sous vide process from hybrid sorubim fillets by using different treatments

The aim of this work was to develop and evaluate ready-made dishes of hybrid sorubim fish fillets obtained by the sous vide process. Three treatments were investigated: T1 with brine containing fine-herbs, T2 with brine containing fine-herbs, olive oil, and rosemary; and T3 with the same brine as in T1 but added of 30% of tomato sauce. Results showed the protein content increased according to the type of liquid medium employed, where the lowest value was determined for T1 and the highest value for T3. The sous vide process did not influence the lipid and protein contents of the treatments, be by the addition of olive oil (T2) nor by tomato sauce (T3). Treatments differed for all sensory attributes and presented acceptability indexes above 78.66%. indicating that they are good alternatives for fish consumption. However, T1 had the highest percentage of purchase intention (97.23%), representing the best product for commercialization.

Designing of specialized fish food products with a reduced content of nitrogen extractives

The authors consider the possibility of using low-value pelagic fish species in the diet of people with restrictions on the consumption of nitrogenous extractive substances including nucleic acids which are sources of purine base metabolism. The objects of the study were chopped mackerel fillets from boiled fish and chopped boiled fillets from raw fish, quick-frozen minced horse mackerel of industrial processing in a boiled form. The studies were carried out in accordance with the experimental plan in which the duration of the heat treatment and the temperature of the cooking medium were the variable factors. The technology of combined fish masses with the addition of functional plant components has been proposed. It has been established that the dynamics of dry matter losses and heat losses of fish fillets is determined by the duration of cooking. In terms of organoleptic characteristics boiled minced meat from raw mackerel fillets is significantly inferior to the organoleptic characteristics of minced meat from pre-boiled fillets. When comparing the data for frozen and freshly prepared mince from horse mackerel, it has been found that the loss of nucleic acids in industrially prepared minced meat is 4.6-13.1 % higher ( T = 82 ± 2 and 98 ± 2 °C), the loss of nucleic acids by absolutely dry matter is higher by 11.3-5.8 %, mass - by 8.4-14.6 %. The content of the total amount of nucleic acids in industrial minced meat is 11.1 % lower than in freshly prepared minced meat. Obviously, in the process of preparing products for specialized purposes, including for preventive nutrition, it is preferable to use minced meat from boiled fish fillets.

Effect of lactic acid and lysozyme on river fish fillets during cold storage

Presented work evaluated how quality of catfish fillets is affected by treatments using lactic acid or lysozyme in combination with chlorine. Fish fillets without skin were consecutively immersed and washed in 100 ppm chlorine solution and sprayed with 2.5% lactic acid or 0.5% lysozyme solution. Control samples were only washed with water at the same time. Samples were stored at 2 °C for 10 days in vacuum packaging. Parameters of pH, firmness, surface color and microbial cell counts (cfu/g) were measured on the 1st, 4th, 7th and 10th days. Especially the latter had high importance from the point of view of food safety. Catfish fillets shown decreased survival of microorganisms as a result of treatment. Lysozyme and lactic acid achieved 1.8 and 2.4 log cfu/g reduction, respectively. Lower cell counts were observed for all treated samples compared to control during 10 days. Chlorine in combination with lactic acid achieved the best efficiency. The results are promising and suggest that combined treatment is able to improve safety by controlling microorganisms on fish fillets during cold storage.