Biochemical, Microbiological, and Sensory Properties of Dried Silver Carp (Hypophthalmichthys molitrix) Influenced by Various Drying Methods

Decoding the effects of brining time on the sensory quality, physicochemical properties and flavor characteristics of marinated grass carp meat

This study aimed to explore the effects of different brining times on the sensory, physicochemical properties, and volatile organic compounds (VOCs) of marinated grass carp (MGC). The results showed that different brining time changed the sensory quality, color and texture. The moisture content increased significantly with the extension of brining time, while the salt content, protein content, thiobarbituric acid reactive substances (TBARS), and total volatile basic‑nitrogen (TVB-N) decreased (p < 0.05). Free amino acids indicated that sweet amino acids significantly decreased, but bitter and umami amino acids increased. E-nose and E-tongue could clearly distinguish different MGC samples, and gas chromatography ion mobility spectrometry (GC-IMS) identified a total of 72 VOCs. Among them, 11 key VOCs were screened based on the variable importance of predicted component value (VIP) and relative odor activity value (ROAV), and they showed a high correlation with MGC quality. This study provides a theoretical foundation for enhancing the quality and improving the flavor of MGC.

Enhancement of nutritional quality and shelf life of fish products (powder & chapatti) via fortifying with orange-fleshed sweet potato

Despite its high protein, fat, and mineral contents, fish contains trace amounts of carbohydrates and vitamins, notably vitamin A. The perishable nature of fresh fish makes it challenging to store for a prolonged time, necessitating the use of additives to enhance its shelf life, nutritional, and other quality aspects. Sweet potatoes are the preferred option to blend with fish due to their cost and abundance. This study aims to prepare fortified fish powder and make food products (chapatti) using it. Fish powder and sweet potato powder were prepared by drying them in an oven at 60°C and 45°C, respectively. The two dried samples were then ground and mixed in various ratios, followed by analyzing their nutritional and other parameters using standard methods. Vitamin A and beta-carotene levels were analyzed using HPLC and UV-Vis spectroscopy techniques, respectively. The findings indicated that the outcomes displayed enhanced nutrition and extended storage capacity. The amount of beta-carotene (876.12 ± 14.76 to 3182.4 ± 123.1 μg/100 g) and carbohydrates (4.49 ± 1.02 to 52.31 ± 0.21) increased. The packed fortified flour is safe for human consumption for up to 90 days, as per the International Commission for Microbiological Specifications for Foods. The chapatti made from fortified flour was also deemed acceptable by the panelists.

Extension of shelf life of Nile tilapia (Oreochromis niloticus) fillets using seaweed extracts during refrigerated storage

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.

Combined Effects of Cold and Hot Air Drying on Physicochemical Properties of Semi-Dried Takifugu obscurus Fillets

The physicochemical properties of semi-dried Takifugu obscurus fillets in cold air drying (CAD), hot air drying (HAD), and cold and hot air combined drying (CHACD) were analyzed based on pH, water state, lipid oxidation, protein degradation, and microstructure, using a texture analyzer, low-field nuclear magnetic resonance, thiobarbituric acid, frozen sections, sodium dodecyl sulfate polyacrylamide gel electrophoresis, and differential scanning calorimetry. Water binding to the samples was enhanced by all three drying methods, and the immobilized water content of CHACD was between that of HAD and CAD. The pH of the semi-dried fillets was improved by CHACD. When compared to HAD and CAD, CHACD improved the springiness and chewiness of the fillets, especially cold air drying for 90 min (CAD-90), with values of 0.97 and 59.79 g, respectively. The muscle fibers were arranged compactly and clearly in CAD-90, having higher muscle toughness. CHACD reduced the drying time and degree of lipid oxidation compared to HAD and CAD. CAD better preserved protein composition, whereas HAD and CHACD promoted actin production; CHACD had a higher protein denaturation temperature (74.08-74.57 °C). CHACD results in better physicochemical properties than HAD or CAD, including shortened drying time, reduced lipid oxidation, enhanced protein stability, and denser tissue structure. These results provide a theoretical basis for selecting the appropriate drying method for T. obscurus in industrial applications.

A Comprehensive Review on the Processing of Dried Fish and the Associated Chemical and Nutritional Changes

Fish is a good source of nutrients, although it is easily spoiled. As such, drying is a common method of preserving fish to compensate for its perishability. Dried fish exists in different cultures with varying types of fish used and drying methods. These delicacies are not only consumed for their convenience and for their health benefits, as discussed in this review. Most commonly, salt and spices are added to dried fish to enhance the flavours and to decrease the water activity (aw) of the fish, which further aids the drying process. For fish to be dried effectively, the temperature, drying environment, and time need to be considered along with the butchering method used on the raw fish prior to drying. Considering the various contributing factors, several physicochemical and biochemical changes will certainly occur in the fish. In this review, the pH, water activity (aw), lipid oxidation, and colour changes in fish drying are discussed as well as the proximate composition of dried fish. With these characteristic changes in dried fish, the sensory, microbial and safety aspects of dried fish are also affected, revolving around the preferences of consumers and their health concerns, especially based on how drying is efficient in eliminating/reducing harmful microbes from the fish. Interestingly, several studies have focused on upscaling the efficiency of dried fish production to generate a safer line of dried fish products with less effort and time. An exploratory approach of the published literature was conducted to achieve the purpose of this review. This evaluation gathers important information from all available library databases from 1990 to 2022. In general, this review will benefit the fishery and food industry by enabling them to enhance the efficiency and safety of fish drying, hence minimising food waste without compromising the quality and nutritional values of dried fish.

Effects of Various Drying Methods on Physicochemical Characteristics and Textural Features of Yellow Croaker (Larimichthys Polyactis)

The physicochemical characteristics and textural properties of yellow croaker treated by hot air drying (HAD), low temperature vacuum drying (LVD), and freeze drying (FD) methods were studied. The dried fish by LVD had the lowest moisture content and highest protein. The volatile basic nitrogen values of dried fish by HAD, LVD, and FD were 66.27, 34.38, and 33.03 mg/100 g sample, respectively. The predominant amino acids of dried fish treated by LVD and FD were lysine, taurine, alanine, and glutamic acid, and the predominant ones by HAD were the remaining amino acids analyzed in this study, except lysine, taurine, alanine, and glutamic acid. By using the color parameters, the L* and b* values by LVD showed light brown and yellow colors of the fish. The textural properties of dried fish by LVD were softer and more chewable than those of HAD and FD. In the stereo-micrographs, the flesh of dried fish by LVD compared to others showed minimization of texture damage, resilient tissues, much fish oil, and were light brown in color. Taken together, these results suggest that LVD rather than HAD and FD provide good qualities of dried fish in terms of physicochemical characteristics and textural properties.

Changes in Physicochemical, Microbiological, and Sensory Properties of Sun-Dried Mystus vittatus During Storage at Ambient Temperature

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.