Nutritional, textural and quality attributes of white and dark muscles of little tuna (Euthynnus affinis)

205-211The proximate composition, fatty acid profile, texture, colour and freshness of white and dark muscles of little tuna (Euthynnus affinis) were investigated. The moisture content was higher in white muscle (75.52±0.13%) compared to that in dark muscle (74.85±0.10%). Both white and dark muscle had higher levels of protein, 23.12± 0.13% and 23.15± 0.02%, respectively. Analysis of fatty acid profile by gas chromatography showed that the dark muscle had high levels of eicosapentaenoie acid (C20:5) and docosahexaenoic acid (C22:6) compared to white muscle. Texture profile analysis showed that dark muscle had higher values for hardness (3.74±0.15kgF), whereas adhesiveness, cohesiveness, springiness and chewiness values were greater for white muscle. Colour analysis revealed dark muscle had lower L* value than that of white muscle. The total volatile base nitrogen, tri - methyl amine, texture profile analysis and histamine contents were higher in dark muscle. Overall nutritional quality of dark muscle was superior to that of white muscle

Distribution of luminescent Vibrio harveyi and their bacteriophages in a commercial shrimp hatchery in South India

Luminescent Vibrio harveyi is a natural microflora of marine and coastal water bodies and is associated with mortality of larval shrimp in penaeid shrimp hatcheries. It is also known that the bacteriophages occur virtually in all places where their hosts exist. In this study, distribution of luminescent V. harveyi and the bacteriophages affecting these hosts was examined in a commercial Penaeus monodon hatchery during three shrimp larval production cycles, including a cycle affected by luminescent bacterial (LB) disease outbreak

A Nonluminescent and Highly Virulent Vibrio harveyi Strain Is Associated with “Bacterial White Tail Disease” of Litopenaeus vannamei Shrimp

Recurrent outbreaks of a disease in pond-cultured juvenile and subadult Litopenaeus vannamei shrimp in several districts in China remain an important problem in recent years. The disease was characterized by “white tail” and generally accompanied by mass mortalities. Based on data from the microscopical analyses, PCR detection and 16S rRNA sequencing, a new Vibrio harveyi strain (designated as strain HLB0905) was identified as the etiologic pathogen. The bacterial isolation and challenge tests demonstrated that the HLB0905 strain was nonluminescent but highly virulent. It could cause mass mortality in affected shrimp during a short time period with a low dose of infection. Meanwhile, the histopathological and electron microscopical analysis both showed that the HLB0905 strain could cause severe fiber cell damages and striated muscle necrosis by accumulating in the tail muscle of L. vannamei shrimp, which led the affected shrimp to exhibit white or opaque lesions in the tail. The typical sign was closely similar to that caused by infectious myonecrosis (IMN), white tail disease (WTD) or penaeid white tail disease (PWTD). To differentiate from such diseases as with a sign of “white tail” but of non-bacterial origin, the present disease was named as “bacterial white tail disease (BWTD)”. Present study revealed that, just like IMN and WTD, BWTD could also cause mass mortalities in pond-cultured shrimp. These results suggested that some bacterial strains are changing themselves from secondary to primary pathogens by enhancing their virulence in current shrimp aquaculture system

Phage Therapy and Photodynamic Therapy: Low Environmental Impact Approaches to Inactivate Microorganisms in Fish Farming Plants

Owing to the increasing importance of aquaculture to compensate for the progressive worldwide reduction of natural fish and to the fact that several fish farming plants often suffer from heavy financial losses due to the development of infections caused by microbial pathogens, including multidrug resistant bacteria, more environmentally-friendly strategies to control fish infections are urgently needed to make the aquaculture industry more sustainable. The aim of this review is to briefly present the typical fish farming diseases and their threats and discuss the present state of chemotherapy to inactivate microorganisms in fish farming plants as well as to examine the new environmentally friendly approaches to control fish infection namely phage therapy and photodynamic antimicrobial therapy

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Not AvailableLuminescent Vibrio harveyi has been reported to be one of the major causes of mass mortality of larval stages in penaeid shrimp hatcheries throughout the world. Therefore, understanding the virulence mechanism of V. harveyi and identifying traits has been our quest to detect pathogenic strains in shrimp aquaculture ecosystem. In this study pulsed field gel electrophoresis (PFGE)was used for differentiating V. harveyi isolates recovered from shrimp larvae affected by luminescent bacterial disease in hatcheries and water samples from various sources within the hatcheries. Forty two of the 400 V. harveyi isolates recovered from shrimp hatcheries over a period of two years were used in this study. Cluster analysis of PFGE profiles of 32 V. harveyi isolates in conjunction with virulence factors revealed that the isolates from disease episode were grouped in Cluster II. Further, the isolates in the cluster were all sucrose fermentative and had LD50 value in the order of 103 cfu ml-1 and ranged from 1.17 x 103 cfu ml-1 to 3.16 x 103 cfu ml-1. However, the clustering pattern could not be associated with LD50 values based on in vivo pathogenicity experiment. An interesting observation was that majority of the isolates capable of producing siderophores were clustered in IA (11 of 13) although 10 of the 16 isolates in cluster IB also produced siderophores. Six of 13 isolates in cluster IA and 7 of 16 isolates in cluster IB produced extracellular proteins (ECP) and this property was not found to be associated with any of the clustering pattern. This study could not show definite relationship between pulsotypes and virulence of V. harveyi. However, PFGE typing cluster analysis could help in differentiating isolates from disease episodes and normal shrimp seed production cycle. Further, the study has also revealed that sucrose fermenting trait seems to be animportant phenotypic trait indicative of virulence of V. harveyi in shrimp hatchery ecosystems.Not Availabl

A One-Step Method for the Growth of Ga2O3-Nanorod-Based White-Light-Emitting Phosphors

A one-step synthesis of Ga2O3 nanorods by heating molten gallium in ambient air at high temperatures is presented. The high-temperature synthesis creates oxygen vacancies and incorporates nitrogen from the environment. The oxygen vacancy in Ga2O3 is responsible for the emission in the blue-green region, while nitrogen in Ga2O3 is responsible for red emission

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Not AvailableThe present study aimed to develop bioactive edible coating (BEC) solutions from gelatin and chitosan,incorporated with different concentrations of clove oil as a natural preservative and evaluate their effect on shelf life of tuna fillets. The antibacterial activity against 11 fish spoilage and fish-borne bacteria were tested by agar well diffusion method, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). Gram positive bacteria were more susceptible than gram negative bacteria. Among all the tested bacteria, Bacillus cereus and Staphylococcus aureus were most sensitive to BEC solutions. The tuna fillets were dipped in BEC solutions with different concentrations viz., 1%Acetic acid, 1% Chitosan (C), 1% Gelatin + 1% Clove oil (GC), 1% Chitosan + 1% Clove oil (CC), 1%Gelatin + 1% Chitosan + 1% Clove oil (GCC) and changes in APC, TBARS, TVB-N and sensory values were studied during storage under refrigerated condition (4°C). The fillets without dip treatment was considered as control. Dip treatment of BEC solutions significantly delayed the rate of microbials poilage and extended the shelf life of tuna fillets by six days during refrigerated storage. Solutions incorporated with clove oil, especially fillets treated with 1% gelatin + 1% chitosan + 1% clove oil (GCC)solution had better in-vitro antimicrobial properties and showed excellent preservative action on tuna fillets. The BEC solutions incorporated with clove oil demonstrated its potential as an excellent natural antibacterial agent which can be used as an effective alternative to synthetic antibacterial agents and could be used for packaging of tuna and other fishery products.Not Availabl

Seasonal variation in the proximate composition of sardine (Sardinella gibbosa) from Thoothukudi coast

800-806Seasonal variation in the proximate composition (moisture, protein, fat, carbohydrate and ash) of sardine (Sardinella gibbosa) was analysed for one year (June 2013 to May 2014). In addition, the fatty acid profile and protein fractions (sarcoplasmic, myofibrillar and stoma proteins) of the sample collected in the month of May 2014 were also analysed. Protein, fat, carbohydrate and ash content were varied significantly (P<0.05) from 15.43 to 22.76%, 1.25 to 6.77%, 0.47 to 0.89% and 1.78 to 3.21% respectively. Lipid content of sardine was high during November 2013 to January 2014 (6.21 – 6.77%) and least in the month of May 2014 (1.25%). Sardine sample collected in May 2014 was rich in PUFA especially EPA (C20:5) and DHA (C22:6). Analysis of protein fraction in sardine collected in the month of May 2014 showed that the sardine muscle contains 23.81% sarcoplasmic, 71.97% myofibrillar and 3.20% stroma proteins. The results showed no marked the variation in the protein, carbohydrate and ash contents, whereas, greater seasonal variation in the lipid content of the sample. Lipid content increased from the month of June 2013, reaching a maximum of 6.77% in November 2013, was almost stable in December 2013 (6.33%) and January 2014 (6.21%), after where it decreased as low as 1.25% in May 2014

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Not AvailableSeasonal variation in the proximate composition (moisture, protein, fat, carbohydrate and ash) was analysed in emperor fish (Lethrinus lentjan). Mineral composition (iron, phosphorus, sodium, potassium and calcium) was also analysed. Moisture, protein, fat, carbohydrate and ash contents were found to range from 74.93–78.20, 14.53–24.40, 0.21–2.76, 0.49– 1.07 and 1.24–2.70% respectively. Iron, phosphorus, sodium, calcium and potassium was 4.20, 13.50, 7.20, 156.20 and 17.90 mg% respectively. Fatty acid profile of emperor fish revealed palmitic acid (C16), stearic acid (C18) and myristic acid (C14) to be the major saturated fatty acid and elaidic acid (C18:1n9T) and oleic acid (C18: 1n9C) were the dominant monounsaturated fatty acids. Investigations also revealed that fat content was higher during the monsoon season (October and November).Not Availabl