An investigation was carried out to compare the physical, chemical, microbiological and sensory properties of three freshwater dried fish products of Wallago attu Bloch & Schneider, 1801 (Siluriformes: Siluridae), Channa striatus (Bloch, 1793) (Perciformes: Channidae) and Glossogobius giuris (F. Hamilton, 1822) (Perciformes: Gobiidae). The traditionally sun dried fishes were collected from Kawran Bazar Fish Market, Dhaka, Bangladesh. Results showed that the water reconstitution properties varied among the dried fishes where maximum rehydration was observed in the C. striatus at room temperature, 40 ºC and 60 ºC. Moisture content of W. attu, C. striatus and G. giuris were 22.70% ± 0.45%, 18.75% ± 0.58% and 21.93% ± 0.54%, respectively; the protein content were 61.85% ± 0.99%, 66.44% ± 1.02% and 62.83% ± 0.87%, respectively; the lipid content were 6.21% ± 0.93%, 6.81% ± 0.72% and 5.98% ± 0.55%, respectively, and the ash content were 6.79% ± 1.11%, 6.49% ± 1.29% and 7.83% ± 0.98%, respectively. Peroxide value, acid value, pH, TVB-N value and aerobic plate count were found to be highest in W. attu followed by G. giuris and C. striatus. Results of this study revealed that traditionally sun dried fish products were acceptable quality in terms of physico-chemical, microbiological and sensory aspects.

An experiment was performed to evaluate the effects of different drying methods with different pre-treatments on the physico-chemical, microbiological, and sensory properties of the silver carp, Hypophthalmichthys molitrix. In order to achieve this objective, the collected fresh fish were dried using traditional (without any pre-treatment), improved (fish soaked in a 5% salt solution for 10 min and then treated with chili powder (0.3%) and turmeric powder (0.3%)), and solar tunnel (fish soaked in a 5% salt solution for 10 min) drying methods. The results showed that the dried fish produced by the solar tunnel drying method were rehydrated more rapidly than the products produced by the traditional and improved drying methods. The moisture content of the dried H. molitrix was varied from 18.24 to 25.43% on a fresh matter basis. There was no significant (p > 0.05) difference found regarding the protein, lipid, and ash content among the different drying methods on a dry matter basis. The total volatile base nitrogen (TVB-N) contents ranged between 37.58 and 45.03 mg/100 g, and significantly (p < 0.05) the lowest TVB-N was observed in dried fish produced by the solar tunnel drying method. Moreover, the highest peroxide and acid values were found in the traditionally produced dried fish as compared with the fish dried by the improved and solar tunnel drying methods. The aerobic plate count of dried fish ranged from 4.52 to 7.51 log CFU/g. The sensory evaluation results revealed that the solar-dried products showed superior quality than the products produced by the traditional and improved drying methods. The results revealed that the dried fish produced by the solar tunnel drying method provided the best product in terms of physico-chemical, microbiological, and sensory aspects.

The objective of this study was to investigate the changes in physicochemical, microbiological, and sensory properties of sun-dried Mystus vittatus during storage at ambient temperature. The fish was dried under sun exposure on bamboo mats for 5–6 days until the moisture content reduced to approximately 10–15%. The dried fish was then packed into airtight polyethylene bags and stored at ambient temperature (24 to 29 °C) for 90 days. The physical and sensory properties revealed that the dried fish was acceptable for human consumption for up to 60 days. The pH value slightly decreased from 6.42 to 5.95 during the storage period. The moisture content increased significantly (p < 0.05), while no significant difference was observed for the protein, lipid, and ash contents (on a dry matter basis) with the increase in the storage time. The peroxide value, acid value, and conjugated dienes of the lipids increased significantly during the storage period. The microbial load also increased with the increase in the storage period. The results of this study suggest that the product was slightly oxidized during the storage period and could be stored for up to two months.

The effects of seaweed (Padina tetrastromatica, Sargassum natans, and Sargassum fluitans) ethanolic extracts on the quality and shelf life extension of Nile tilapia (Oreochromis niloticus) fillets were investigated during refrigerated storage for 20 days. Each of the seaweed ethanolic extracts solution (2%, w/v) was used for dipping the fish fillets for 10 min at 4°C. The control and seaweed extract‐treated fillets were stored at 4 ± 1°C in air‐tight polyethylene bags, and chemical, bacteriological, and sensory evaluation were performed at every 4 days' intervals. During the storage period, P. tetrastromatica extract significantly (p < .05) reduced the increment of pH, peroxide value, thiobarbituric acid reactive substances, and total volatile basic nitrogen values in Nile tilapia fillets compared to other seaweed extracts‐treated and untreated fillets. The maximal total viable count of control, P. tetrastromatica, S. natans, and S. fluitans extracts‐treated fillets was 6.53, 7.11, 6.75, and 7.10 log CFU/g at the 8th, 20th, 12th, and 16th days of storage, respectively. The total psychrotrophic count of control and seaweed extracts‐treated fillets was also significantly increased (p < .05) throughout the storage period. The P. tetrastromatica extracts‐treated fillets showed better sensory characteristics than other seaweed extracts‐treated and control fillets. Results of this study suggest that ethanolic extracts (2%, w/v) of P. tetrastromatica extend the shelf life for 12 days longer than the control fillets in refrigerated conditions.

A natural product such as chitosan promotes health benefits and extends the shelf life of the processed products. Chitosan has been used as a food additive due to its antioxidant and antimicrobial activities. This study was conducted to optimize the chitosan concentration as a coating agent on the quality and shelf life of Labeo rohita fillets during frozen storage. Chitosan (CH) solutions were prepared with 0.5 %, 1 %, and 2 % (w/v) CH in 1 % (v/v) glacial acetic acid for coating application. The control (0% CH) and CH treated fish fillets were stored at -18 °C for 14 weeks and assessed for chemical (pH, thiobarbituric acid reactive substances (TBARS), total volatile basic nitrogen (TVB-N), and K-value), microbiological (aerobic plate count (APC)), and sensory properties. The pH, TBARS, and K-value of 1 % and 2 % CH treated fish fillets were acceptable up to 14th week of storage, while TVB-N value was permissible up to 12th week of storage. After 14th week of storage, the APC of control, 0.5 %, 1 %, and 2 % CH treated fillets were 7.18 log CFU/g, 5.02 log CFU/g, 4.13 log CFU/g, and 3.21 log CFU/g, respectively. The fish fillets treated with 1 % and 2 % CH had acceptable sensory attributes up to 12th week, while control fillets were unacceptable after the 6th week of storage. This study demonstrated that 1% CH could be used as a natural additive for keeping the quality and extending the shelf life of L. rohita fillets during frozen storage.

Sun dried (T. fasciata) was stored with airtight polyethylene bags at room temperature to investigate the changes in physical, chemical, microbiological and sensory characteristics for 90 days. Sensory and physical (water reconstitution, pH) characteristics of dried T. fasciata showed that the product was acceptable up to 60 days of storage. Moisture content of T. fasciata was significantly increased from 15.06% to 17.80% during the storage period. No significant difference was observed in protein, lipid and ash content on dry matter basis during storage. However, amount of lipids of the dried fish was slightly decreased with the increasing of storage time. The pH value of dried T. fasciata was decreased significantly from 6.51 to 5.94 during the storage period. The peroxide value was increased from 13.84 to 27.87 meq/Kg of lipid. Similarly, acid value and conjugated diene of the lipids were increased significantly, and this result suggested that lipid oxidation occurred over this period of time. Microbial load was also increased from 1.13 to 8.37 log CFU/g with the increasing of storage time. Results of this study showed that the product was oxidized marginally during the storage period and suitable for human consumption up to 60 days.