---

The effects of cooking methods on sensory attributes and physical properties (firmness, normal shear, cooking loss and color based on L*, a* and b*) of rainbow trout (Oncorhynchus mykiss) fillet was investigated. The study was based on application of autoclavingat 120 °C for 5 and 10 minutes, deep frying of the flour coated fillet at 180 °C for 2 and 5 minutes and microwaving at 600 watt for 2, 4 and 6 minutes. Cooking loss significantly differed among the cooking methods, the highest of which occurred in 6 minute microwaved treatment. The highest and the least color changes were, respectively, recorded in coated fillet fried for 5 minute and for 2 minute microwaved fillet treatment. In terms of normal shear results, control and 2 minute fried fillet treatment had the hardest tissue, respectively. Also the penetrate tests revealed a significant difference between control and other treatments (p< 0.05) as the hardest tissue was the one that fried for 5 minute and the softest one was the control. However, the highest score was allocated to the fried and 6 minute microwaved treatments by the panelists. Based on the sensory evaluation, fillet fried for 5 minute was found as a preferred cooking method.

---

The effect of ascorbic acid on shelf life of rainbow trout (Oncorhynchus mykiss) fillets in the refrigerator based on total microbial load, chemical evaluation was investigated. For this reason, the fish were divided into three groups, including without injections (treatment 1), fish with intravenous injection of ascorbic acid in doses of 0.1 and 0.3% (treatment 2 and 3) and fish with intramuscular injection in doses of 0.1 and 0.3% (treatments 4 and 5). After 62 hours of injection, fish (400 ±10g) were caught and filleted, then kept for 16 days in refrigerator. During this period, every 4 days, peroxide value (PV), thiobarbituric acid (TBA), free fatty acids (FFA), total volatile nitrogen base (TVB-N) and total bacterial load (TVC) indicators were measured. Treatments 3 and 5 showed a significant difference (p≥0.05) in PV, TBA, FFA, TVB-N and TVC indicators in comparison to other treatments. There was also a significant difference between the treatments 3 and 5 (p≥0.05) in the indicators of the TVC, TBA, FFA and TVB-N that indicated better performance of intravenous injection of ascorbic acid 0.3% after 8 days storage in comparison to intramuscular injection of 0.3%. According to the results, in intramuscular or intravenous injection of different doses of ascorbic acid increased the shelf life of rainbow trout fillet during storage in the refrigerator until day 12.

---

The present study was conducted to evaluate the effect of antimicrobial coating on the shelf-life of trout fillet. Antimicrobial coatings were obtained by incorporating cinnamon oil in coating formulations prepared from chitosan. Coated fish were stored at refrigerated (4±1˚C) and were periodically evaluated for Total viable counts, psychrophilic counts, lactic acid bacteria and Enterobacteriaceae as well as total volatile basic-nitrogen(TVB-N) and pH. Sensory evaluations were performed for Texture, odor, color, overall acceptability. Results showed that cinnamon oil and chitosan coating had synergistic effects (P < 0.05) in reducing the Total viable counts, psychrophilic counts, lactic acid bacteria and Enterobacteriaceae. Chitosan coated enriched with cinnamon significantly (P < 0.05) reduced chemical spoilage as reflected in TVB-N .Texture, odor, color, overall acceptability significantly (P < 0.05) changed only for the control samples.   

---

In addition to health effects, plant extracts can be used as natural preservatives with antioxidant and antimicrobial properties in the food industry. In this study, effect of antioxidant and antimicrobial properties of ethanolic extracts of watercress on the chemical and microbial quality of rainbow trout fillet at refrigerator temperature for 12 days was investigated. After drying the leaves at darkness and room temperature extract was extracted with 45, 65, 75 and 96% ethanol solvents for 24 hours at 65 °C. The results showed a significant difference (P≤0.05) in yields and phenolic content, 0.1 mg /ml of extract 65% with an extraction efficiency of 20% the highest amount of total phenol (88.60 ± 2.46%), DPPH (84.73 ± 0%); and ABTS (83.83 ± 0.06%) were. Also, the growth inhibition of the pathogenic bacteria Listeria monocytogenes, Escherichia coli, Staphylococcus aureus and Salmonella enteritidis in sample extracted with 65% ethanol had a significant difference with other extracts (P≤0.05). Rainbow trout fillet samples in 65% ethanol extract showed lower levels of TVB-N, PV and TBA to the control treatment during storage (P≤0.05). Rainbow trout fillet samples in 65% ethanol extract showed lower levels of TVB-N, PV and TBA indices of fillets compared to control treatment during storage (P≤0.05). Talking about bacterial index, the amount of total and pseudomonas bacteria in the treatment containing the extract did not reach the maximum allowable limit (10⁶ cfu /g^-1) by the twelfth day, Indicates the effectiveness of the extract on increasing the shelf-life of fillets compared to the control.
 

---

Whey protein based edible coating containing 0.5, 1 and 1.5% (w/v) thyme essential oil was used for inhibition of bacterial growth of rainbow trout fillets during cold storage. Microbial analyzes (total viable counts, psychrophilic counts, lactic acid bacteria and Enterobacteriaceaeas) as well as total volatile basic-nitrogen(TVB-N) and pH measuring were performed periodically every four days. Results showed that whey protein coating containing thyme essential oil was able to inhibition of bacterial growth of fish fillets. Also the TVB-N and pH values in the coated samples were significantly (p<0.05) lower than those of non-coated treatment. Among the treatments used in this study, treatment with 1.5% thyme essential oil containing edible coating was the most effective treatment against evaluated bacteria in this study. As could extend the shelf-life of rainbow trout fillets stored at refrigerator for at least 4 days compared to control.  

---

This research carried out to study the effects of probiotic coating alginate and whey protein with Pediococcus acidilactici and Lactobacillus plantarum to increase the storage of rainbow trout fillet (Oncorhynchus mykiss) at refrigerated temperature and to evaluate the physical characteristics of the fillets. Thus, the physical parameters such as color and texture of fillets were investigated at 0, 7, 14 and 21 days. Results showed that, the color index (L*, a*, b*) and texture index (hardness cycle, deformation at hardness, and firmness) in treated fillets were better than control. In other words, the use of probiotic coating caused a decrease in the index of redness of the fillet on the 21st day; on the other hand, the yellowness index was lesser. In terms of texture indices such as hardness cycle, deformation at hardness, and firmness, using probiotic coatings in higher percentages of alginates and whey protein resulted in better preservation of fillet tissue quality than other treatments.

---

The effect of chicken feet gelatin coatings and green walnut husk extracted on chemical, physical, microbial and sensory properties of rainbow trout fillet was investigated during storage period (12 days) at 5 °C. Chemical analyses (pH, TVB-N, TBA and FFA measurements), physical tests (moisture, color and texture measurements), microbial tests (TVC) and sensory evaluation were carried out periodically every four days. The results showed that by increasing the concentration of walnut green skin extract, the efficiency of the coating increased that the coatings containing 2.5 and 5% gelatin along with 1000 ppm of the extract improved the quality and shelf life of fish fillets compared to other ones. The values ​​of pH, TVB-N content, TBA and FFA in coated samples were significantly lower than the control sample (p<0.05). The coating treatment containing 1000 ppm of the extract also maintained the moisture, texture and color of the fillets and showed a lower microbial load than other treatments. From a sensory point of view, the treatments containing chicken foot gelatin and walnut green skin extract had the highest score at the end of the storage period compared to the control sample. Furthermore, the highest score was obtained for the samples coated by 1000 ppm walnut green skin extract.

---

Today, the use of active packaging containing natural antimicrobial compounds such as essential oils and plant extracts has increased to increase the shelf-life of food  products. The purpose of this study is to investigate the effect of gelatin coating containing Citrus sinensis peel extract on increasing the shelf life of rainbow trout meat. Gelatin (4%) coating was prepared with different levels of Citrus sinensis peel extract (2% and 4%). After preparing the pieces of rainbow trout meat, all the pieces were coated and examined for chemical properties (pH, TVB-N, TBARS), microbial (TVCs and TPCs) and sensory properties (odor, color, texture and overall acceptance) were evaluated for 16 days at 4°C with a 4-day interval (0, 4, 8, 12, 16). The results of the investigation of the antimicrobial effect showed that in the samples coated with 2% and 4% levels of Citrus sinensis peel extract, the average count of mentioned bacteria was significantly lower than the control and gelatin alone (p < 0.05). The results of examining the chemical properties of the samples showed that pH, TVB-N and TBARS increased during the period, but this increase occurred at a slower rate in the samples coated with different levels of Citrus sinensis peel extract. In the evaluation of sensory characteristics, at the beginning of the study, all the samples had the highest acceptance limit, and with the passage of time and the appearance of signs of spoil, the scores decreased, especially in the control. Generally, the results showed that gelatin coating along with different levels of Citrus sinensis peel extract has a positive effect on increasing the shelf life of fish meat and these compounds can be used together to increase the shelf life of protein foods.
 

---