This study evaluated the microbiological quality and sensory characteristics of rainbow trout (Oncorhynchus mykiss) fillets processed by the sous-vide method under chilled storage at 4 ºC. Two different heat treatments were studied (65 ºC for 15 min and 85 ºC for 5 min). For this, vacuum packed fillets of rainbow trout cooked in a water bath. After reaching a core temperature of 65 and 85 ºC, cooking was prolonged for 15 and 5 min, respectively for first and second treatment, then samples were stored in refrigerator (4 ºC) for 21 days. Results showed that microbial counts decreased by increasing the heating temperature and increased by increasing storage time. The heat treatment of 85 °C was the most effective one to ensure the safety and extend the shelf life of sous-vide trout fillets to preserve the sensory characteristics. Based on these results, sous-vide samples had an acceptable sensory quality after 21 days of storage at 4 ºC.
A preliminary risk assessment of the trace metals accumulated in the farmed Beluga sturgeon (Husohuso) caviar from Caspian Sea/ (Original research paper)
Beluga sturgeon (Huso huso), the source of beluga caviar, is so depleted that they were included on the list of endangered species by the convention on international trade in endangered species (CITES), and it is estimated that overfishing for meat and caviar will soon cause global extinction on the remaining natural wild population; so production of caviar using aquaculture is seen as a feasible way to prevent extinction of this species. The concentration of Ca, Co, Cr, Cu, Fe, K, Mg, Mn, Se and Zn as essential metals, were determined in caviar of farmed Beluga sturgeon. Co and Mn levels in the samples were less than 0.01 mg kg-1 wet weight. The mean concentration of Cu and Zn in the caviar samples were under the permissible limits proposed by the UK’s ministry of agriculture, fisheries and foods (MAFF). The caviar maximum allowable daily consumption rate was calculated. However, the health risks from caviar consumption are uncertain because the amount of caviar consumed by heavy users is not known.
Effects of chitosan coating on the quality of rainbow trout fillet during storage in refrigerator / (Original research paper)
The aim of the present study was to evaluate the effects of chitosan coating on quality and shelf life of fresh rainbow trout (Oncorhynchus mykiss) in refrigerator (5±1 °C). Fishes were slaughtered quickly and fresh samples were treated with a solution of 2% (w/v) medium molecular weight chitosan dissolved in glacial acetic acid randomly and stored in refrigerator for 15 days. Then all the samples were investigated for psychrotrophic bacteria count and also sensory analysis within 3 day intervals. As shown results illustrated that the initial bacterial load was 2.51±0.3 log10 CFU g-1 in chitosan coated samples followed by 2.93±0.5 log10 CFU g-1 in control samples. These values were increased to 6.51±0.3 and 8.5±0.5 log10 CFU g-1 for chitosan coated and control samples, respectively. Thus, it could be concluded that chitosan coating can retard the microbial growth for treated samples and also extend the shelf life of rainbow trout in refrigerator significantly (p<0.05).
Effect of cooking method on fatty acid composition of Oyster (Crassostrea gigas)/ (Original research paper)
Page 16 - 20
Chuah Leong, Chin Kee Mahani, Pan Cheng Keong, Yeo Monte
In the present study the effect of some processing techniques on the fatty acid composition of oyster, a member of bivalves, was investigated. Results showed that, applied processing methods such as smoking, pickling, and different kinds of cooking are recorded to have caused important changes in the fatty acid composition. It was also seen that these changes were occurred from eicosapentaenoic (EPA) (C20:5n-3), and docosahexaenoic (DHA) (C22:6n-3) which are important especially in human health. Results illustrated a decrease in different proportions in the quantity of eicosapentaenoic and docosahexaenoic acids. It seems that, Maximum decrease in the mentioned fatty acids was especially observed in the fried and cooked samples.
Fatty acid composition and qualitative changes of salted rainbow trout (Oncorhynchusmykiss) roe during refrigerator storage/ (Original research paper)
Fish roe is an important source of polyunsaturated fatty acids, protein and essential amino acids, minerals and vitamins. The amount of salt in salted fish roe brought about increasing its shelf life but it could also cause qualitative changes. After initial washing, the rainbow trout roes divided into two groups: raw roe (control) and salted roe (1.5% pure salts). The results showed that unsaturated fatty acids in the control were between 73.83 and 64.45% but in the salted roe, it was in the range of 71.06 to 70.46%, Qualitative factors in the control group showed significant difference over the time. Conversely, there were no significant differences in the salted roe during the cold storage. Thus, the salting can be a good way to increase shelf life with maintaining high quality in the roe. Practical application: Rainbow trout roe with low salt content showed both sensorial acceptance and shelf life extension. Hence, adding low salt into the roe could be marketed as compared with medium and high salt content of fish roe in market.
Changes of biogenic amines in silver carp (Hypophthalmichthysmolitrix) fillet under different packaging conditions/ (Original research paper)
A comparative study of the eﬀects of different packaging on the formation of biogenic amines during storage of silver carp (Hypophthalmichthys molitrix) at 4 ºC was carried out. Silver carp fillet were stored in air, modiﬁed atmosphere packaging (MAP) and vacuum packaging (VP). Silver carp fillets were mmicrobiologically acceptable for up to 4 days in air, 12 days in MAP and 8 days in VP. The biogenic amine content generally increased in all treatments with increasing storage time. The concentrations of putrescine and/cadaverine in ﬁsh stored in air reached maximum levels of 132.18 mg 100 g-1 and 143.4 mg 100 g-1 after 16 days, respectively Signiﬁcant diﬀerences were found (p<0.05) in the levels of cadaverine and putrescine among the three treatments. Spermidine and spermine levels increased slightly and did not change much throughout the storage period for all experimental conditions. The amine contents of silver carp were highest in silver carp stored in air, followed by VP and MAP. The use of MAP showed an with carbon dioxide to extension the shelf-life (approximately four days) of silver carp by inhibiting microbial growth compared to air and VP. Quality indices related to the contents of the major biogenic amines were calculated and they correlated well with microbiological indices.
An overview of some of the packaging methods of fish/ (Review paper)
Food packaging is necessary for storage, suitable distribution and maintaining the quality. Fish has a high nutritional value and their consumption is highly recommended. Per capita consumption of fish is low in Iran. This is due to factors such as lack of access to high quality and fresh fish and supplied of without packaging or improper packaging. Marine products are more susceptible to spoilage than other meat products. Packaging is one of the most common and easy methods to maintain the freshness of fisheries products from the catch to consumption. There are different methods for packaging of fish and its products. Some of the methods such as modified atmosphere packaging (MAP) and vacuum packaging are widely used for fisheries products. MAP has become a popular method for packaging of foods as it can extend the shelf life of food. One of the new methods of seafood packaging is the edible films and coating. Edible films and coatings are thin layers which are used both in surface and in between the various layers of food. In this paper, three common packaging methods of seafood i.e. MAP, vacuum packaging and edible films and coatings are reviewed.