نشریه علوم و فنون شیلات
سال هشتم شماره 4 (پیاپی 28، پاییز 1398)

The aim of this study was to investigate the effect of cooking (frying and microwave), chitosan additive and freezer storage on the fish fillet in terms of sensory and color evaluation and weight changes.

Cultivated fish fillets, frozen at -18 ° C for 4 months. They were then transferred to the Fisheries Processing Laboratory of the Faculty of Fisheries, Gorgan University of Agricultural Sciences and Natural Resources, in the shortest possible time (day 0, day 2 and month 4). The fillets were frozen and cooked in a pan and microwave. The experiment was designed in 4 treatments: T1 (fried sample without chitosan), T2 (fried sample containing 1% acid-soluble chitosan), T3 (microwave cooked sample without chitosan), T4 (Microwave cooked sample containing 1% acid-soluble chitosan). Fillet weights were measured before and after cooking. Sensory evaluation and colorimetric evaluation of fillets were also performed after cooking.

The use of 1% acid soluble chitosan had no significant effect on sensory parameters and colorimetric factors (p> 0.05). Weight changes in fried fillets increased over time but decreased in microwave-cooked fillets over time.

The use of natural additives such as acid soluble chitosan 1% had no significant effect on the sensory indeces compared to the control group. In terms of colorimetric factors, chitosan had a positive effect on yellowness index. In terms of cooking and having a safe product, it is very important that the weight factor of the microwave cooked fillets is more favorable than the fried fillets.

Histopathological study is one of the most appropriate ways to evaluate the effects of contaminants in aquatic organisms. The aim of this study was to evaluate the histopathological changes and histopathological alternation index (HAI) in liver tissue of Pomadasys kaakan and Lutjanus johnii in the Oman Sea.

In this study, 18 number Pomadasys kaakan and Lutjanus johnii were captured from there stations Ramin, Konarak and Haft Tir by gillnet in winter 2016. In order to study the type and severity of tissue lesions, liver tissue of both fish species were performed fixation stages in Bowen's solution, tissue processing in tissue processing device, paraffin impression, tissue sections 4-5 microns thickness with microtome, stained with hematoxylin and eosin.

Tissue lesions observed in fish livers included hepatocyte vacuolization, enlargement of sinusoid, adipose cell accumulation, blood congestion, nuclear pyknosis, hemorrhage and necrosis. Tissue lesions observed in the liver of both fish species were higher in Haft-Tir station and lower in Ramin station than in other stations. Histopathological alternation index in liver tissue of both fish species were higher in Haft-tire station than in the other two stations.

Due to the high traffic of the Haf-Tir dock and its close proximity to other docks in the area, the accumulation of pollutants at this station is more and to cause more severe tissue lesions in fish.

In this study, gelatin was extracted from Siberian sturgeon waste and used in film making.

Gelatin was extracted using NaOH and HCl. After evaluating the extracted gelatin properties (bloom grade, pH, zeta test, melting and setting temperature and time), the edible film was prepared by using glycerol.

The results showed that the extraction efficiency of the gelatin was %20.06. The protein content, pH, degree of gel hardness, setting and melting temperature and time were 79.2 ± 0.6%, 4, 160.2 ± 0.4 g, 13.1 ± 0.2 ° C in 180.3 ± 0.5 seconds and 19.33 ± 0.5 ° C in 140.66 ± 0.5 seconds, respectively. Zeta potential indicated a positive surface charge in gelatin. The thickness, moisture, solubility, tensile strength, tensile strength and permeability tensile strengths properties of gelatin film reported 0.05 mm, %10.2 ± 1.5, %79 ± 3.7, 30.01 ± 0.7 MPa, %77.5 ± 3.6 and 3.5 ± 0 g mm/h mm2kpa×10-6 , respectively. SEM images of the film showed smooth structure without cracking. Moreover, the FTIR result showed the formation of amide bands in the region of 3277.62, 1633.92, 1530.11 and 1236.49 cm-1.

Due to the efficiency and properties of gelatin, and the mechanical and physical properties of the edible film, it can be used as a good candidate for the production of biodegradable films in food storage.

For the purpose of marketability and consumer preferences, two types of hand moisturizing products (Alginate gel and Fucoidan cream) produced from Sargassum algae, this study was conducted. then evaluated with a common commercial sample as a control.

Gel and two cream samples were prepared in 3 jars of 10 g to evaluate 30 individuals as panel members. Evaluation was performed using one product per week and with a one-week break between sessions. The designed questionnaire consisted of sociological questions and 12 characteristics of the products that were rated with 3 points of preference The Friedman test was used to analyze the ratings and the scoring method was used to identify the final product.

Two characteristics of produced cream and gel (moisturizing and shelf life) at a significant level. The gel had the highest moisturizing capacity and the cream had the highest shelf life. Consumers paid more attention to the nourishing and hydrating properties of the skin, being organic and soft in choosing the suitable moisturizer for their hands. They like moisturizing cream of 250 gr jar. Nutrition and hydrating, therapeutic effect and skin repair were also ranked as high priority. Ultimately, the Fucoidan moisturizing cream gained the highest preference in market.

The Fucoidan cream produced from Sargassum algae compared to alginate gel from this alga, as a moisturizer with suitable shelf-life and have other hand cream properties, can be an acceptable commercial product in the market.

The aim of this study was to investigate effect of pellets contain Spirulina platensis on physiological indices of Ctenopharyngodon idella.

The number of 450 grass carp (10±0.5g) were divided into six treatments (three replicates) and fed with pellets contain 0, 0.5, 1, 2, 4% spirulina for eight weeks, compared to forage (control). At initial and the end of experiment, growth and nutrition indices, meat composition, hematological and immunological indices, and carotenoid of fish were mesured. Means were compared by one-way ANOVA, Tukey test (p ≤ 0.05).

The best total length, weight, FCR, SGR, body weight gain, nutritional efficiency, daily growth and dietary intakes were observed in 4% Spirulina treatment, which showed significant difference with control (P˂0.05). Fat percentage of meat in 4% Spirulina treatment had difference with control significantly (P˂0.05). The number of RBCs in 1% spirulina treatment had significant difference (P˂0.05) with control. The highest Hct and Hb were observed in 1% spirulina treatment, and the highest WBCs and eosinophils were observed in 4% spirulina treatment, which had significant difference with control. Also, the percentage of lymphocytes in algae-treated treatments was significantly (P˂0.05) higher than control and non-algae-treated treatment. The highest level of lysozyme, bactericidal and anti-trypsin activity of serum were in 4% spirulina which had significant difference with control. Carotenoid of fish meat didn’t show significant difference between treatments.

According to the results, food pellets containing 4% Spirulina is recommended for improving growth and nutrition, hematological and immunological indices in grass carp.

microalgae use has been recently attracted for the production of biologically active drugs and pharmaceuticals.Carbon source is an essential factor for the Spirulina maxima growth. Since finding the appropriate carbon source and its concentration to achieve high levels of biomass in the shortest cultivation period is very valuable. Therefore, the effect of different carbon sources (sodium carbonate, sodium bicarbonate, glucose and molasses) with different concentrations (16, 24 and 32 gL-1) on growth and biomass production were evaluated.

Microalgae was grown in 11 treatments with 3 replications at labarotary temperature (28±3 °C) and 1350±100 Lux light intensity (24 hours exposure-time). Maximum specific growth rate and doubling time were calculated according to nonlinear modeling by Wolfram Mathematica software at 99% confidence interval.

The highest biomass concentration (gL-1) at the highest carbon source concentration in the first 5 days belonged to molasses (3.083), glucose (2.094), sodium carbonate (0.869) and sodium bicarbonate (0.835). Biomass production of treatments except glucose in medium was increased by increasing concentration from 16 to 32 gL-1. Although molasses has reached on highest biomass production during the first 5 days of cultivation, but the greatest effect on increasing specific growth rate belongs to the glucose sample.

As a result, the carbon source and its concentration had a significant effect on the growth and biomass production. Glucose has been selected as an effective carbon source for growth with a concentration of 24gL-1. Moreover, the highest concentration of treatments had shown the least effect on specific growth rate.

The present study was aimed to evaluate the effect of different levels of choline chloride (ziro, 250, 500, 750, 1000, and 2000mg/kg food) on the growth performance, carcass compositions, and haematology of Caspian salmon (Salmo trutta caspius).

270 fish pieces weighing 8.82±0.38 in 18, 250‐liter fiberglass tanks (15 fish per tank) with 3 repetitions per treatment with one of six experimental diets (control diet, Cho250, Cho500, Cho750, Cho1000, and Cho2000) were fed for 10 weeks.

Final weight, weight gain, specific growth rate index, protein yield ratio, obesity ratio, and feed conversion ratio of fish fed with diet containing appropriate levels of choline (750 to 1000mg/kg choline), were significantly higher than the fish fed with control diet and Cho250 diet (p≤0.05). There was a significant decrease in the feed conversion ratio of Cho750 and Cho1000 treatments compared to control treatment. It can be acknowledged that the Caspian Sea salmon cannot meet the physiological needs of choline by biosynthesizing choline from the liver or methionine. By increasing choline in the diet, the amount of protein and fat in the carcass increased significantly, but the moisture content of the carcass decreased (p≤0.05). Also, moderate amounts of fatty liver fish fed with control treatment and Cho250 treatment were significantly lower than other treatments. The results showed a negative relationship between the increase in choline levels and the activity of hepatic blood enzymes (p≤0.05).

In order to increase the growth process, strengthen the immune system, and optimally combine the carcass, the most appropriate amount of choline chloride is 750‐1000mg/kg in the diet of Caspian Sea salmon.