Binaya Bhusan Nayak

Quality of Ready to Serve Tilapia Fish Curry with PUFA in Retortable Pouches

UNLABELLED Studies on the physical, chemical, and microbiological qualities of fresh tilapia meat revealed its suitability for the preparation of ready to eat fish curry packed in retort pouches. Studies on the fatty acid profile of tilapia meat suggest fortification with polyunsaturated fatty acid (PUFA) to increase the nutritional value. Based on the commercial sterility, sensory evaluation, color, and texture profile analysis F(0) value of 6.94 and cook value of 107.24, with a total process time of 50.24 min at 116 °C was satisfactory for the development of tilapia fish curry in retort pouches. Thermally processed ready to eat south Indian type tilapia fish curry fortified with PUFA was developed and its keeping quality studied at ambient temperature. During storage, a slight increase in the fat content of fish meat was observed, with no significant change in the contents of moisture, protein, and ash. The thiobarbituric acid (TBA) values of fish curry significantly increased during storage. Fish curry fortified with 1% cod liver oil and fish curry without fortification (control) did not show any significant difference in the levels of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), during thermal processing and storage. Sensory analysis revealed that fortification of fish curry with cod liver oil had no impact on the quality. Tilapia fish curry processed at 116 °C and F(0) value of 7.0 (with or without fortification of cod liver oil) was fit for consumption, even after a period of 1-y storage in retort pouch. PRACTICAL APPLICATION Tilapia is a lean variety of fish with white flesh and therefore an ideal choice as raw material for the development of ready to serve fish products such as fish curry in retort pouches for both domestic and international markets. Ready to eat thermal processed (116 °C and F(0) value of 7.0) south Indian type tilapia fish curry enriched with PUFA and packed in retort pouch was acceptable for consumption even after a storage period of 1 y at ambient temperature.

Separation of Marine Bacteria according to Buoyant Density by Use of the Density-Dependent Cell Sorting Method

ABSTRACT The purpose of this study was to test whether some phylogenetic groups of natural marine bacteria have unique buoyant densities that allow them to be separated by the density-dependent cell sorting (DDCS) method. We first concentrated a natural bacterial assemblage to collect sufficient numbers of cells. They were separated into three fractions by DDCS, and the community structure in each was clarified by fluorescence in situ hybridization. The cells of Archaea tended to appear in the high-density fraction, whereas those of Cytophaga-Flavobacterium-Bacteroides were in the low-density fraction. We also calculated the sedimentation velocities of three typical marine bacteria (low density, middle density, and high density) using their buoyant density. The sedimentation velocities were approximately 10, 20, and 30 μm h−1; these velocities have ecological implications when the heterogeneity of bacteria is considered at a microscale. To our knowledge, this is the first report on the buoyant density of natural marine bacteria.

Isolation and characterization of Arcobacter spp. from fresh seafood and the aquatic environment.

Arcobacter is an emerging pathogen associated with foods of animal origin. Members of the genus Arcobacter are increasingly being isolated from fish, shellfish and the aquatic environment. In the present study, we analyzed fish, shellfish and water samples for the presence of Arcobacter spp. by conventional isolation as well as by direct PCR on the enrichment broth. Of 100 samples comprising of 42 finfish, 34 shellfish and 24 water samples analyzed, Arcobacter spp. was isolated from 8 (19%) finfish, 5 (14.7%) shellfish and 5 (20.8%) water samples. Arcobacter DNA was detected in 24 (24%) samples by direct PCR on the enrichment broth. Based on m-PCR specific to different Arcobacter spp. and 16S rRNA sequence analyses, majority (19) of the isolates were identified as Arcobacter butzleri, while two isolates were Arcobacter mytili. All Arcobacter butzleri isolates harbored putative virulence genes cadF, ciaB, mviN, pldA, tlyA and cj1349. The two isolates of A. mytili harbored mviN and cj1349 genes only. The study highlights emerging problem of the contamination of aquatic environment and fresh seafood with potentially pathogenic Arcobacter spp.

Studies on the Biochemical Changes During Fermentation of Salt-Fermented Indian Shad (Tenualosa ilisha)

ABSTRACT ‘Lona ilish,’ a traditional salt-fermented fish product made exclusively from Hilsa (Tenualosa ilisha), is widely consumed in Bangladesh and adjoining northeastern part of India. No detailed scientific studies have been made on ‘lona ilish.’ To understand the science behind this traditional preservation process, the product was prepared in the laboratory following traditional method, and biochemical changes during fermentation period of 150 days were studied at two-week intervals. The protein and protein degradation products as well as lipid and its degradation products were among the important parameters studied. Increase in non-protein nitrogen (NPN), free alpha amino nitrogen (FAN), and total volatile basic nitrogen (TVBN) contents during fermentation indicated hydrolysis of protein. However, the decrease in protein nitrogen content was not significant. A value of NPN/TN of 18% in the fish muscle was found indicative of the ripening point. The loss of lipid in the product was found to be significant. The first rise of peroxide value (PV) immediately after dry salting followed a gradual decrease, and thereafter a second rise was observed in the later half of fermentation period. However, this increase of PV did not impart any rancid taint to the end product. High salt content (15.48%), intermediate moisture content (49.89%) and low pH (5.28) of the final product was found to be satisfactory for stability of the ‘lona ilish’ at ambient temperature.

Isolation of Escherichia coli harboring blaNDM-5 from fresh fish in India

Extended spectrum b-lactamase (ESBL)-producing Gramnegative bacteria have become a severe challenge to chemotherapy. The ESBLs are classified into several groups, the prominent of them being TEM, SHV, and CTX-M types. Members of the family Enterobacteriaceae, which cause diverse infections ranging from wound infection to meningitis, are the major ESBL-producing Gram-negative bacteria. Carbapenems are the antibiotics of choice against ESBL-producing bacteria, but the occurrence of carbapenem-resistant enterobacteria (CRE) producing plasmid-encoded metallo-b-lactamases with carbapenemase activity have emerged worldwide. In 2008, a new b-lactamase, the New Delhi metallo-blactamase (blaNDM-1), capable of hydrolyzing all b-lactams with the exception of aztreonam, was identified in Klebsiella pneumoniae isolated from a Swedish patient who was previously treated in India. Subsequently, the NDM-1 producing enterobacteria were isolated from different parts of the world. Studies from India and other countries have reported the occurrence of blaNDM-1 harboring bacteria in the environment. Variants of NDM-1 designated as NDM-2, NDM-4, NDM-5, NDM-6, and NDM-7 have arisen through point mutations. NDM genes are located on a large plasmid which also harbors resistance genes for several antibiotics such as b-lactams, aminoglycosides, sulfonamides, chloramphenicol, and macrolides and this plasmid is highly mobile leading to its rapid dissemination in the environment. Here, we report the isolation of an NDM-5 harboring Escherichia coli from fresh seafood sold in a retail market of Mumbai, India. We investigated the presence of NDM-producing enterobacteria in fresh seafood samples sold in retail markets of Mumbai. A total of 19 samples, which included 14 finfish and five shellfish samples, were analyzed. The bacterial isolations were made on MacConkey agar following enrichment of the sample in enterobacteria enrichment broth (EE broth and Mossel; Hi Media, Mumbai, India). Presumptive

Simultaneous nitrification and denitrification by novel heterotrophs in remediation of fish processing effluent.

Three isolates viz. Lysinibacillus sp. HT13, Alcaligenes sp. HT15 and Proteus sp. HT37 isolated from fish processing effluent and having a C/N ratio of 2, removed 218, 169, and 400 µg cell−1 day−1 NH4+‐N, respectively without subsequent build up of nitrite or nitrate. Ability of the selected isolates in removing NH4+‐N, NO2−‐N, and NO3−‐N was checked in the presence of four commonly reported and tested effluent carbon sources viz. pyruvate, glycerol, methanol, and acetate. Further, when supplemented to fish processing wastewater containing 234 ppm total Kjeldahls nitrogen, Lysinibacillus sp. HT13, Alcaligenes sp. HT15, and Proteus sp. HT37 could remediate 95.74, 86.17, and 76.6% nitrogen, respectively in 48 h. This is the first report of a Lysinibacillus sp. carrying out aerobically the process of simultaneous nitrification and denitrification. The results demonstrate the potential of the isolates for use in treatment of fish processing effluents and demonstrating the efficient removal of ammonia.

Multiple Antibiotic-Resistant, Extended Spectrum-β-Lactamase (ESBL)-Producing Enterobacteria in Fresh Seafood.

Members of the family Enterobacteriaceae include several human pathogens that can be acquired through contaminated food and water. In this study, the incidence of extended spectrum β-lactamase (ESBL)-producing enterobacteria was investigated in fresh seafood sold in retail markets. The ESBL-positive phenotype was detected in 169 (78.60%) isolates, with Escherichia coli being the predominant species (53), followed by Klebsiella oxytoca (27), and K. pneumoniae (23). More than 90% of the isolates were resistant to third generation cephalosporins, cefotaxime, ceftazidime, and cefpodoxime. Sixty-five percent of the isolates were resistant to the monobactam drug aztreonam, 40.82% to ertapenem, and 31.36% to meropenem. Resistance to at least five antibiotics was observed in 38.46% of the isolates. Polymerase Chain Reaction (PCR) analysis of ESBL-encoding genes detected blaCTX, blaSHV, and blaTEM genes in 76.92%, 63.3%, and 44.37% of the isolates, respectively. Multiple ESBL genes were detected in majority of the isolates. The recently discovered New Delhi metallo-β-lactamase gene (blaNDM-1) was detected in two ESBL+ isolates. Our study shows that secondary contamination of fresh seafood with enteric bacteria resistant to multiple antibiotics may implicate seafood as a potential carrier of antibiotic resistant bacteria and emphasizes an urgent need to prevent environmental contamination and dissemination of such bacteria.

Physicochemical and Gel Properties of Myofibrillar Protein from Sin Croaker (Johnius dussumieri) Fish During Ice Storage

ABSTRACT The physicochemical and gel properties of myofibrillar protein (MFP) from sin croaker fish were studied during ice storage for 18 days. Significant changes in the trends of solubility, Ca2+ ATPase enzyme activity, surface hydrophobicity, and water holding capacity of extracted MFP were observed by the 6th day of storage. The Ca2+ ATPase enzyme activity reduced significantly (p < 0.05) by the 6th day of storage. However, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) did not show a remarkable change in the concentration of myosin heavy chain. Surface hydrophobicity increased almost four times from its original value of 18.98 µg; whereas, water holding capacity showed a fluctuating trend during storage. The emulsion capacity of the MFP was in the range of 0.89- to 1.92-mL oil/mg protein during storage. The gel strength value (313.45 g.cm) of heat-induced gel prepared from fresh minced meat decreased significantly (p < 0.05) by the 6th day of ice storage. Texture profile analysis revealed that changes in hardness and gumminess were concurrent to steeply reducing breaking force up to the 6th day. The histological observation showed gradually increasing gaps between muscle fibers. The histological observations and physicochemical quality indicated that the sin croaker fish can be used for producing good quality surimi when stored for up to 6 days in ice.

Involvement of Bacillus licheniformis and Micrococcus kristinae During Ripening of Salt Fermented Indian Shad (Tenualosa ilisha)

ABSTRACT “Lona ilish” is a salt fermented fish product prepared exclusively from fatty Indian shad (Tenualosa ilisha). Despite the presence of salt and metals coming from the container used for fermentation, rancidity is not observed as long as the products are kept immersed in the fermenting brine. To understand the technical principles of this indigenous preservation method, the traditional preparation was followed along with analyses of chemical and microbiological changes. The biochemical and microbiological changes were followed at 15 day intervals during the fermentation period of 150 days. From the 45th day of fermentation onwards, the microbial flora in the product was composed of only two species, tentatively identified as Bacillus licheniformis and Micrococcus kristinae. Because Bacillus licheniformis showed some atypical biochemical reactions, it was tentatively identified as Bacillus licheniformis var. III. These two bacterial species either singly or collectively were involved in the fermentation process.

Bio-chemical composition, functional, and rheological properties of fresh meat from fish, squid, and shrimp: A comparative study

ABSTRACT This study was conducted to evaluate bio-chemical composition, functional, and rheological properties of croaker fish (Johnius dussumieri), Indian squid (Loligo duvaucelii), and white leg shrimp (Litopenaeus vannamei) in fresh condition. The n-3 fatty acids were slightly higher in croaker fish (14.91 %) compared to that in Indian squid (13.59 %) and white leg shrimp (13.02 %). The solubility and viscosity of croaker fish proteins were significantly (p < 0.05) lower as compared to shrimp and squid proteins, while the emulsion capacity was higher for squid proteins. The histological study of squid muscles revealed a unique and strong arrangement of myofibrils. Dynamic viscoelastic behaviour of fresh meat of croaker fish and white leg shrimp revealed that transition from sol to gel took place between 48°C to 65°C and 39.93°C to 64.30°C, respectively, while in case of Indian squid, gel formation (increase in G’) progressed mainly in two steps: the first step at low temperature range of 5–28.41°C and the second step over 45°C. Along with this, gel breakdown occurred in the range of 28–45°C. Our study suggested that the temperature range for sol to gel transformation differs from species to species considerably and hence, a specific temperature range may be determined to have maximum gelling ability for every fish species used as raw material for gel-based formulations.