Trimethylamine Nitrogen Research Articles

Chilled storage study of marinated and vacuum‐packed steaks of Otolithes cuvieri (Trewavas, 1974)

SummaryThis study investigates the potential of marination in extending the shelf life of vacuum‐packed croaker fish (Otolithes cuvieri, Trewavas, 1974) steaks by evaluating their organoleptic, biochemical and microbiological characteristics under chilled storage conditions (4 ± 1 °C) for 21 days. The marination process involves the use of natural preservatives such as salt, vinegar and spices, aiming to enhance flavour and texture. Results demonstrated that marination effectively reduces the rate of increase in total plate count (TPC), trimethylamine nitrogen (TMA‐N), total volatile basic nitrogen (TVB‐N), pH, peroxide value (PV) and free fatty acids (FFA) during storage, thereby extending the shelf life of the tested samples. Control (C) and marinated (M) samples of vacuum‐packed fish steaks remained organoleptically acceptable until the 9th and 15th days of chilled storage respectively. Due to the addition of marinating ingredients, significant changes were observed in taste, texture and proximate content. The maximum extension in shelf life for marinated samples is attributed to the combined antimicrobial and antioxidative effects of the different ingredients used in the marination process. These findings suggest that marination holds promise as a method for preserving fish products and satisfying consumer preferences for flavourful, ready‐to‐cook and economically viable seafood options.

Droplet-based luminescent sensor supported onto hydrophobic cellulose substrate for assessing fish freshness following smartphone readout.

In this work, two sensitive droplet-based luminescent assays with smartphone readout for the determination of trimethylamine nitrogen (TMA-N) and total volatile basic nitrogen (TVB-N) are reported. Both assays exploit the luminescence quenching of copper nanoclusters (CuNCs) produced when exposed to volatile nitrogen bases. In addition, hydrophobic-based cellulose substrates demonstrated their suitability as holders for both in-drop volatile enrichment and subsequent smartphone-based digitization of the enriched colloidal solution of CuNCs. Under optimal conditions, enrichment factors of 181 and 153 were obtained with the reported assays for TMA-N and TVB-N, respectively, leading to methodological LODs of 0.11mg/100g and 0.27mg/100g for TMA-N and TVB-N, respectively. The repeatability, expressed as RSD, was 5.2% and 5.6% for TMA-N and TVB-N, respectively (N=8). The reported luminescent assays were successfully applied to the analysis of fish samples, showing statistically comparable results to those obtained with the reference methods of analysis.

New coating containing chitosan and Hyssopus officinalis essential oil (emulsion and nanoemulsion) to protect shrimp (Litopenaeus vannamei) against chemical, microbial and sensory changes.

In this study, the effect of chitosan coating containing emulsion and nanoemulsion of Hyssopus officinalis essential oil (EO) on the chemical, microbiological and sensory characteristics of shrimp (Litopenaeus vannamei) was investigated. The minimum value of TVB-N (Total volatile basic nitrogen), TBARS (Thiobarbituric acid reactive substances), PV (peroxide value), TMA-N (Trimethylamine-nitrogen) and FFA (Free fatty acids) after 12days were shown in NE+HEO 1% (coating containing chitosan with nanoemulsion of EO) with 20.53mgN/100g, 0.5µg/kg, 0.88 MAQ peroxide/kg, 1.3mg/100g and 12.16mg 100% of oleic acid, respectively. Also, minimum value of pH after 12days was related to the CE+HEO 1% (coating containing chitosan with emulsion of EO) with 7.60. The minimum value of psychrophilic and mesophilic microbial count after 12days were shown in NE+HEO 1%, 4.40±0.36 and 4.03±0.06cfu/g, respectively. The best score of sensory evaluation was observed in the NE-HEO 1% treatment. As a result, the edible coating containing chitosan-based nanoemulsion could be effective to the preservation of shrimp's microbiological, chemical, and sensory characteristics.

Quality Changes in Intermediate Flying Fish, Cheilopogon intermedius Parin, 1961, During Ambient and Ice Storage

Intermediate flying fish, Cheilopogon intermedius, Parin, 1961, is a popular source of inexpensive animal protein in the Philippines, but it remains susceptible to deterioration during processing. The study evaluated the sensory, microbiological, and physico-chemical characteristics of flying fish, C. intermedius stored at ambient conditions (27– 29 °C) and on ice (1–2 °C) storage. The storage duration of flying fish was 8 h at ambient temperature and around 12 days in ice. A ten-member taste panel rejected raw fish due to strong fishy to sour odours and soft texture. Similarly, cooked samples were rejected based on sour and ammoniacal odours, mushy texture, and a bitter taste. Results of sensory evaluation correlated with those of microbial and chemical analyses. Bacteria multiplied rapidly at ambient temperature with values of 11.05 log CFU.g-1 and 7.55 log CFU.g-1 (P < 0.05) for total viable count (TVC), and H2Sproducers count, respectively, at the end of the 20-h storage. In comparison, bacterial counts remained below rejection limits until the end of the storage period for samples stored in ice. Total volatile base nitrogen (TVB-N) and trimethylamine nitrogen (TMA-N) accumulated rapidly at ambient temperature, reaching 86.86 mg.100 g-1 and 35.65 mg.100 g-1, respectively, at the end of the storage period. In ice, TVB-N, TMA-N, and histamine values were slowed down, reaching rejection limits only at the end of the storage period. Moreover, the K value increased linearly at ambient storage, while a gradual increase was observed for samples stored in ice. Therefore, without the application of adequate icing, flying fish would undergo rapid decomposition at ambient temperature.

Shotgun metagenomics and physicochemical insights into the effects of temperature on bacterial community and related metabolism in fermented skates

Fermented skate, an indigenous fermented fish, is traditionally produced by spontaneous fermentation in Korea, wherein the fermentation temperature plays a vital role. To understand the effect of fermentation temperature on fermented skate, this study investigated the impact of fermentation temperature on the quality characteristics and microbial diversity of skates during fermentation at 25 and 10 °C. The physicochemical properties of the skate, including the pH, color, textural profiles, trimethylamine nitrogen, total volatile base nitrogen, ammonia nitrogen, and urea contents, were determined during weeks 1 and 2 of fermentation at 10 and 25 °C, respectively. In addition, the microbial diversity of the fermented skates at 25 and 10 °C was compared by shotgun metagenomic sequencing. This study also examined the correlation between physicochemical and metagenomics. At the genus level, Paenalcaligenes, Clostridium, and Bacillus were the predominant bacteria in the skate sample fermented at 25 °C, whereas the dominant genera in the skate fermented at 10 °C were Psychrobacter and Sporosarcina. At the species level, Psychrobacter sp. DAB_AL43B and Psychrobacter arcticus were predominant species in the skate fermented at 10 °C, whereas Paenalcaligenes hominis and Erysipelothrix rhusiopathiae were predominant species in skate fermented at 25 °C. Based on these results, it was observed that the fermentation temperature affected the fermentation period and quality and the bacterial abundance at the endpoint of fermentation in the fermented skate. These results can serve as a valuable resource to produce high-quality fermented skates at appropriate fermentation temperature.

Evaluation of total volatile bases and trimethylamine in hake (Merluccius capensis) fish preserved at low temperature in Vanderbijlpark, South Africa

Fish is one of the most highly perishable food product and its quality aspects are of significance to retailers and consumers. The purpose of this study was to investigate the change in quality of hake (Merluccius capensis) fish preserved at -14°C over a period of seven weeks in other to evaluate fish spoilage indicators. The fish quality parameters assessed were pH, trimethylamine nitrogen (TMA-N) and total volatile bases nitrogen (TVB-N). The data revealed that there was an increase in pH from 7.4 to 7.7 during the storage period. The concentration of TVB-N in the hake samples increased from 7.21 to 23.35 (± 0.036) mg-N/100g while that of TMA-N increased from (range: mean ± std) 3.18 - 3.34: 3.25 ± 0.068 to 13.90 – 15.01: 14.29± 0.493 mg-N/100 g within the seven weeks of preservation, with percent increase of 69.13% (TVB-N) and 77.26% (TMA-N) of the initial amount. The overall data exhibited a steady and consistent increase in the amount of TVB-N, TMA-N and pH in the flesh of hake fish preserved at the temperature and duration of the study. This steady increase in these chemical parameters is a significant potent warning to consumers to resist lengthy storage of fresh fish and its products before consumption. One-way analysis of variance was adopted to assess the validity of the parallel increase of TVB-N, TMA-N, pH with storage duration at low temperature and the analysis revealed no significant differences between increase in the three chemical parameters and storage time. In other words increase in TVB-N, TMA-N, pH content is directly proportional to the increase in storage time. This study have provided useful data to benefit South African retailers on storage and maintenance of TVB-N and TMA-N limits of acceptance in the consumption quality of hake to be sold to consumers and also for consumers on storage duration of hake in their refrigerators before consumption.

Effect of plant extracts on quality characteristics and shelf-life of cold-marinated shrimp (Parapenaeus longirostris, Lucas, 1846) under refrigerated storage

The effects of rosemary (Rosmarinus officinalis), lemon balm (Melissa officinalis), lavender (Lavandula angustifola), oregano (Origanum vulgare) and savory (Satureja montana) extracts, alone and in mixtures, on lipid oxidation in cold-marinated shrimp (Parapenaeus longirostris) were studied. During the two-month screening period using the thiobarbituric reactive substances assay (TBARS) the most effective extract mixture (rosemary:oregano:lavender extracts in 3:2:1 ratio, ROL) was selected for the shelf-life study in pilot production of marinated shrimp to determine its effects on the quality characteristics of the final product. Degradation of the omega-3 fatty acids, eicosapentaeonic acid (EPA) and docosahexaenoic acid (DHA) during 8 months of refrigerated storage, was inhibited in shrimp marinated with ROL compared to control samples. In addition, lower levels of total volatile basic nitrogen (TVB-N) and trimethylamine nitrogen (TMA-N) were observed in shrimp treated with extracts while the TBARS values remained below the limit of 3 μmol malondialdehyde (MDA)/100g during the 8-month shelf-life study period, whereas the control sample exceeded this value in the third month. The total number of aerobic mesophilic and psychrophilic microorganisms was reduced after marinating with extracts. The obtained results are promising with regard to the application of plant extracts, especially the tested ROL mixture, to extend the shelf-life of food products and to reduce lipid oxidation and microbial load in the food model.

Evaluation of sensory and chemical quality difference of frozen gadus morhua in open markets of Imo state, Nigeria

A total of forty (40) frozen Gadus morhua obtained from cold room and open markets of three Local Government areas of Imo state were evaluated for their sensory qualities employing the use of nine panelist guided by questionnaire on general appearance, taste, smell and texture and chemical quality changes in their ammonia (AMM), total volatile base nitrogen (TVB-N), trimethylamine nitrogen TMA-N), acid value (AV), free fatty acid (FFA) and pH at the hands of the final consumers. Results were analysed using a one way analysis of variance employing SPSS package and compared using the Duncan multiple range test. Results shows that frozen Gadus morhua obtained from the cold rooms and open markets in the three local government areas under study had very good qualities for general appearance of 1.22±0.56 and 2.40±0.72 as the highest mean respectively. The very good quality still persists in the grilled (cooked) samples of the fish. A significant difference in AMM, TVB-N, TMA-N, AV and FFA at p≤0.05 with p-values of 0.00, 0.00, 0.00, 0.00 and 0.02 respectively was recorded while pH values remained insignificantly different at p-value of 1.00. During the fish storage in ice, volatile compounds such as ammonia (NH3) and trimethylamine (TMA), are produced by autolytic and bacterial processes, resulting in an ammoniacal and strong fish odour, typical of deteriorated fish. These parameters generally are indicators of fish spoilage. Significant rise in Ammonia value from 15.65 0.04 for cold room samples to 20.96 0.78 from an open market in Ohaji LGA and TMA-N cold room values of 2.46 ± 0.39 to 3.95 ± 0.45 from an open market indicating fast rate of spoilage which is concluded to be due to the unsafe exposure of fish and its handling after it must have left the cold rooms. Even though the values obtained in open markets were still good, quality loss was signiificantly observed. It is recommended that sanitary and food inspection agencies resume function in our markets to reduce the risk of fish contamination which subsequently reduces its quality.

SENSORY AND BIOCHEMICAL QUALITY CHANGES OF CATLA (CATLA CATLA) IN IMMEDIATE AND DELAYED ICING AND AT AMBIENT TEMPERATURE

Changes in the quality of Catla (Catla catla) stored immediately (0 h) in ice, after six (6) hours in ice and at ambient temperature soon after catch was investigated. The samples were examined by sensory (organoleptic and rigor mortis progress) and biochemical parameters (total volatile base nitrogen, trimethylamine nitrogen and pH). The rigor mortis proceeded faster in fish stored at ambient temperature (28°C-30°C) than those stored in ice (0°C). The duration of full rigor stage and total rigor period were 8h and 13h for fish stored in ambient temperature and 77h and 127h for fish stored in ice (both immediate and delayed icing) respectively. Organoleptically, the acceptability of fish varied between 16-20 days in both the iced storage conditions and 12-13.5h at ambient temperature. The fishes were organoleptically just acceptable on the 16th day of storage and just unacceptable on the 20th day. The values of total volatile base nitrogen (TVB-­N), trimethylamine nitrogen (TMA-N) and pH were 18.9 mg% (0h), 16.74 mg% (6 h), 5.40 mg% (0h), 4.86 mg% (6h) and 6.93 (0h), 6.65 (6h) respectively at the time of rejection for fish stored in ice. Those values for fish stored at ambient temperature were 28.44 mg%, 6.22 mg% and 7.18 respectively at the time of rejection.

POST MORTEM VARIATION OF TOTAL VOLATILE BASE NITROGEN (TVB-N) AND TRIMETHYLAMINE NITROGEN (TMA-N) IN VETKI (Lates calcarifer)

Total Volatile Base Nitrogen (TVB-N) and Trimethylamine Nitrogen (TMA-N) contents of Vetki (Lates calcarifer) were investigated following Conway’s Microdiffusion technique at 4 hour interval in Fish Quality Control Laboratory, Fisheries and Marine Resource Technology Discipline, Khulna University. Observed TVB-N and TMA-N value did not vary significantly among different size classes. At fresh condition, TVB-N content was observed as 11.106±0.8 mg, 11.162±0.8 mg, and 11.162±0.8 mg in small, medium and large size classes of fish respectively and it increased to 59.087±0.8 mg, 68.417±1.5 mg and 75.967±2.7 mg for 100 g-1 respectively at complete spoilage stage (after 28 hrs). At fresh condition, TMA–N content was 6.7±0.016 mg, 11.069±1.79 mg and 11.172±1.01 mg for 100 g-1 in small, medium and large size classes of fish respectively and it increased to 48.893±3.01 mg, 52.492±.089 mg and 57.717±1.95 mg for 100 g-1 respectively at complete spoilage stage. TVB-N and TMA-N values started to increase gradually in all size groups with the passage of time but the rate of increase became faster after 20th hour and continued till the final stage was reached.

DEVELOPMENT OF PICKLE FROM MARINE MOLLUSKS AND ITS SHELF-LIFE ASSESSMENT DURING STORAGE

In the southwestern part of Bangladesh, mollusk such as oysters, blood clam, mussels and horn snails are used only for lime production, whereas they also have other potential purposes of use. The flesh of edible blood clam (Anadara granosa) and oyster (Crassostrea madrasensis) are not utilized by the people because of lack of awareness about the high nutritive value of the seafood products. Keeping this in mind, an attempt was made to utilize mollusk flesh as pickle. The shelf life of the pickled product developed from blood clam and oyster were assessed for a period of 6 months at ambient temperature (28-32 °C). Three types of oils, such as mustard oil, sesame oil and soybean oil were used for pickle preparation, where mustard oil was selected as the best pickle on the basis of biochemical, microbiological and sensory evaluation. Trimethylamine nitrogen, total volatile base nitrogen, total plate count and sensory scores of pickles with mustard oil were significantly increased (P <0.001) at the end of storage period though all scores were at acceptable limit. The cost of preparing pickle was found very low. It may also contribute to our blue economy by marketing and exporting pickles to foreign countries. In future, the pickle prepared from unutilized mollusk meat may be used as food for tribal people in Bangladesh and also have economic value in the tourist area for foreign tourists.

Chemical and microbial changes of stingray fish (Trygon sephen) during soaking in salt solution before smoking process

The salting process at a fisherman's level is still traditional and does not yet have a standard for salt concentration and soaking time, thus affecting the freshness and quality of fish for further processing. For this reason, it is necessary to conduct research that can maintain the quality of fish before the smoking process to ensure results can be recommended for fellow fishermen. This research aimed to find the best quality of lowsalted stingray fish (Trygon sephen) treated with different salt solution concentrations and soaking time durations before the smoking process. This study used three levels of salt solution concentration (10%, 20%, and 30% w/v, respectively) as the first factor and soaking time duration (1 hr, 2 hrs, and 3 hrs) as the second factor. Chemical and microbial analyses of samples were performed during treatment to investigate their quality. The results showed that stingray fish soaked in 10% salt solution for 1 hr was the best treatment. In this treatment, the pH, total plate count (TPC), total volatile base nitrogen (TVB-N), and trimethylamine nitrogen (TMA-N) values were 6.92, 4.98×105 CFU/g, 6.12 mg N/100 g, and 5.56 mg N/100 g, respectively. Meanwhile, protein loss in this treatment was 2.66. In conclusion, treatment with 10% salt solution for 1 hr could be used in stingray fish considering that this treatment resulted in good quality with the lowest protein loss. Furthermore, this treatment is used as a reference for the smoking process because the concentration of the salt solution is low and the soaking time duration is short.

Effects of bioactive substances to prolong the shelf‐life and inhibit the formation of black spots in black tiger shrimp (Penaeus monodon) preserved at 0 degree C

AbstractThe objective of this study was to extend the shelf‐life and inhibit the process of black spots formation in giant black tiger shrimp (Penaeus monodon) by using 1.5 % solutions of the bioactives including: gallic acid, caffelic acid and cinnamaldehyde. Shrimp samples were dipped in the solutions for ten minutes, at 4°C and stored at 0°C for 15 days. Total viable count (TVC), melanosis evaluation method, chemical quality indexes including total volatile base nitrogen (TVB‐N), trimethylamine nitrogen (TMA‐N), pH and hypoxanthine values were used to evaluate the effectiveness of the treatments. TVC values, melanosis score of shrimp samples treated with bioactive compounds appeared more slowly, TVB‐N and TMA‐N values changed exponentially, hypoxanthine values increased linearly with storage time, and pH decreased on day 2, then increased gradually. Shelf life of treated samples were found to be longer than that of the control sample (8 days), and had a better ability to inhibit melanosis, in particular, the samples treated with a solution of cinnamaldehyde had the longest shelf life of 14 days, compared with 13 days of samples treated with caffelic acid and 12 days of the ones treated with gallic acid.

Effect of Locust Bean Gum-Sodium Alginate Coatings Combined with High CO2 Modified Atmosphere Packaging on the Quality of Turbot (Scophthalmus maximus) during Refrigerated Storage

This research was conducted to investigate the effect of active coatings composed of locust bean gum (LBG) and sodium alginate (SA) containing daphnetin emulsions (DEs) combined with modified atmosphere packaging (MAP) on the microbiological and physicochemical properties of turbot during 4 °C refrigerated storage for 32 days. The results revealed that LBG-SA-DE coatings together with high CO2 MAP (60% CO2/35% N2/5% O2) maintained the total viable count (TVC) of H2S-producing bacteria in 4–6 lg CFU/g, which is lower than the limit (7 lg CFU/g). In addition, LBG-SA-DE coatings together with high CO2 MAP (60% CO2/35% N2/5% O2) inhibited the production of odor compounds, including thiobarbituric acid (TBA), trimethylamine-nitrogen (TMA-N), K value, and total volatile basic nitrogen (TVB-N). The low-field NMR analysis (LF-NMR) and magnetic resonance imaging (MRI) indicated that LBG-SA-DE coatings together with high CO2 MAP (60% CO2/35% N2/5% O2) treatments could delay the release of water located in muscle fiber macromolecules or convert it into free water based on muscle fiber destruction, thus maintaining the water content and migration. The results of the sensory evaluation showed that turbot treated with LBG-SA-DE coatings together with MAP could maintain its freshness during refrigerated storage.

Microbial Characterization of Yellow Curing Process of Codfish.

Yellow cured codfish has a typical yellow colour, distinctive taste, and low salt content due to its special curing process of the raw salted codfish involving several soaks in water of the raw salted codfish, alternated with drying steps. The purpose of this study was to assess the main functional groups of bacteria involved in this process and relate them with physicochemical properties of the product. A total of 28 codfish from Iceland were supplied by two local companies. Seven stages of the curing process were analyzed. From each of these seven stages, four fish samples were collected to carry out the microbial and physicochemical analyses (moisture, salt content, pH, total volatile basic nitrogen (TVB-N), and trimethylamine nitrogen (TMA-N)). Bacteria counts were performed using the MPN method and adequate culture media for aerobic, proteolytic, sulphite-reducing, biogenic amine, and trimethylamine-producing and ammonifying bacteria. Strains isolated from the highest dilutions with microbial growth were used to characterize the predominant bacteria. The results showed that total aerobic counts increased from 3.9 log MPN/g in raw salted codfish to 5.9 log MPN/g in the final. Proteolytic, ammonifying, and trimethylamine bacteria producers also increased to 8, 7.5, and 6.5 log MPN/g, respectively. The salt content decreases (from 17% until 8%) and moisture increases (53% until 67%) during the salted-raw-codfish soaking, favoring sulphite-reducing and biogenic amine-producing species, confirming that desalting enhances potential spoilers. The subsequent drying step benefits proteolytic, ammonifying, and trimethylamine-producing bacteria, with a corresponding non-protein-nitrogen content (TVB-N and TMA-N) increase. The dominant bacteria during yellow curing belong to the genera Staphylococcus, Psychrobacter, Pseudomonas, and Alcaligenes with a clear positive correlation between the content of Staphylococcus and Psychrobacter and TVB-N and TMA-N concentration. Staphylococcus spp. are the dominant bacteria in the steps where the product has a higher salt concentration; thus, it could be particularly useful as an indicator to control the industrially yellow curing process and could have an important role in the development of the final characteristics of this product.

Characterization of volatile compounds and physicochemical properties of hongeo using headspace solid-phase microextraction and gas chromatography-mass spectrometry during fermentation

Changes in the volatile composition and some chemical properties of fermented skate, hongeo at different stages in its fermentation process were investigated using headspace solid-phase microextraction and gas chromatography-mass spectrometry. The result showed that a significant increase in pH, ammonia nitrogen, total volatile base nitrogen (TVBN) and trimethylamine nitrogen (TMAN) content during fermentation. A total of 208 volatile compounds, consisting mainly of hydrocarbons, alcohols, ketones, esters, amines, aldehydes, sulfur compounds, indoles, phenols, and other compounds, were detected and identified. Volatile compounds including amines, hydrocarbons, and alcohols were dominant in the unfermented hongeo samples, whereas pyrazines, indoles, phenols and sulfur compounds appeared from the early or middle stage and increased until the end of fermentation. The significant increase in abundance and relative content of volatile compounds at the initial fermented stage indicated that the metabolic activity of microorganisms plays an important role in the formation of the unique flavor. We present SPME/GC-MS as a useful tool for monitoring the volatile compounds of hongeo during fermentation, and provide important information for investigating the mechanism of unique flavor formation in hongeo products.

Development of a PCL-PEO double network colorimetric pH sensor using electrospun fibers containing Hibiscus rosa sinensis extract and silver nanoparticles for food monitoring

Major anthocyanin, cyanidin-3-sophoroside (318.1 mg/mL), and other minor copigments were identified in the ethanol extract of Hibiscus rosa sinensis. The extracts can be coelectrospun with polycaprolactone and polyethylene oxide into fiber mats and were sensitive to pH changes from 1 to 13 with a unique color code (ΔE > 5). The pH sensor was used to monitor shrimp quality under isothermal conditions to obtain the respective activation energy (Ea in kJ/mol) of the sensors’ color-change response (20.2), measured pH (20.6), and trimethylamine nitrogen (24.6), indole (27.1), and total microbial counts (30.8). Together with the Pearson correlation coefficient, the results showed high correlations between the sensors’ color change and other quality parameters (p < 0.001). The regression equation developed by conducting the kinetic analysis was also suitable for predicting shrimp quality at refrigeration temperatures (4–10 °C) and can be used as a marker to monitor shrimp quality by visually inspecting the item condition.

Effect of rosemary extract and vitamin e on lipid peroxidation and the quality during chilling and frozen storage of fried Nile tilapia fillets (Oreochromis niloticus)

Antioxidants are added to fresh and processed meat to prevent lipid oxidation, retard development of off-flavors, and improve color stability. In the food industry, they can be divided into natural and synthetic antioxidants. Synthetic antioxidants have been confirmed for their toxicological and carcinogenic effects. Thus, the food industry now chooses natural products over synthetic ones. This study was carried out to investigate the effect of Rosemary extract (R.E.) and vitamin E on the quality of fried fillets of Nile tilapia (Oreochromis niloticus) during chilling and frozen storage. Fillets of Nile tilapia were treated with (R.E.) 0.1%, 0.2%, 0.3% and Vitamin E 0.1% then stored for 5,10 and 15 days at 4±1°C and for three months at -18±2°C. Then chemical tests including Peroxide value (PV), Thio-barbituric acid (TBA), Tri-methylamine-nitrogen (TMA-N) and Total volatile base-nitrogen (TVB-N) were done to evaluate the preservative effect of (R.E.) and vitamin E during storage. The TBA and PV increased in all treatments due to lipid peroxidation. Results showed that TMA-N,TVB-N, value of (R.E.) and vitamin E treated samples were significantly lower than those of the control samples (P&lt;0.05). Results of our investigation revealed that R.E. retarded oxidative changes in chilling and frozen fried fillets of Nile tilapia whereas R.E. 0.1%, 0.2% and vitamin E 0.1% were not as effective as R.E. 0.3% on oxidative stability. Best oxidation inhabitation results on chilling and frozen fried fillets of Nile tilapia was obtained when employing of R.E. The obtained results also showed that there was a significant (p&lt;0.05) enhancement in sensory quality attributes of fried fillets of Nile tilapia; samples treated with R.E. and vitamin E Conclusion: The tested R.E. had a high effectiveness as antioxidative and antimicrobial should be utilized for extending the shelf-life through retarded the spoilage and enhancing quality attributes of fried fillets of Nile tilapia during chilling and frozen storage.

Effects of Plant Extracts on the Quality of Sous Vide Meagre (Argyrosomus regius) Fillets

This study aimed to determine the changes in the quality of sous vide meagre (Argyrosomus regius) fillets that have been treated with oregano and rosemary extracts during the cold storage (4±1 °C). Saturated fatty acids, monounsaturated fatty acids, and polyunsaturated fatty acids dominant in meagre fish were found to be palmitic acid, oleic acid, and linoleic acid, respectively. pH values fluctuated during storage in sous vide samples. It was determined that total volatile basic nitrogen (TVB-N), thiobarbituric acid (TBA) and trimethylamine nitrogen (TMA-N) values did not exceed the limit values during the storage period in the Control SV, Rosemary SV, and Oregano SV groups. The total number of mesophilic aerobic bacteria (TMAB) and total psychrophilic aerobic bacteria (TPAB) on the 42nd day did not exceed the limit values in the Control SV, Rosemary SV, and Oregano SV groups. During the cold storage, lactic acid bacteria, yeast, and mold were not detected in sous-vide cooked groups. It has been determined that rosemary and oregano extracts improve the sensory quality of the product in taste and smell.

A Review on Solar Drying of Fish

Oman is one of the larger fish producers in the region. Due to high perishable rate of fish products, many preservation techniques were used such as smoking, drying, chilling, brining and freezing. Solar drying is the most popular technique due to its simplicity and low cost compared to other techniques. Objective. This study aims to review the different types of solar drying techniques and highlight the quality measures of solar dried fish. Review findings. Solar drying techniques can be divided into three types; open-sun drying, direct and indirect solar drying. The open-sun drying is the most adoptable method because it is the cheapest preservation technique. However, this technique has several drawbacks such as the uncertainty of weather, large implementation area, time-consuming, poor drying rate, high labour costs, attacking by insects, microorganism and birds, and mixing with dust and foreign materials. Solar dryers, on the other hand, overcome most of the drawbacks associated with open-sun drying. They have shorter drying time and higher drying rate, and at the same time they enhance the physical properties of dried fish. For better understanding of the drying processes many regression models were used and the exponential model was found to be the best fitted model describing the drying behaviour. The fish have very good nutritional value due to higher amount of proteins, lipids and ash contents with comparison to fresh fish. For higher shelf life fish has to meet certain characteristics with respect to pH, water activity, microbial load, total volatile base nitrogen (TVB-N), trimethylamine nitrogen (TMA-N) and enzymatic autolysis. For a very good quality, the pH must be ranging from 6.0-6.9 and the water activity must be lower than 0.7. The TVB-N and TMA-N are indicators of spoilage and their upper acceptable limits are 10-15 mg/100g and 35-40 mg/100g, respectively. Total plate count (TPC) and total fungal count (TFC) are two attributes used to assess the microbiological quality of fish products. The autolysis changes in the fish lead to spoilage as a result of the production of biogenic amines and microbial growth. Conclusions. Studying the health aspect of dried fish is very important for the human body to obtain a greater proportion of proteins and important substances away from the harmful chemicals that may appear in traditional draying technique.