Peer Reviewed Journal Articles (Inter.) (FP)
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- ItemOptimization of the multispecies probiotic combination with N-acylhomoserine lactone-degrading ability for increased disease resistance of Carassius auratus using response surface methodology(Elsevier, 2021-10-20)In the present study, two N-acyl homoserine lactone degrading bacteria (Lactobacillus plantarum QQ8 and Lactobacillus casie QQ10) isolated from the gastrointestinal tract of Oreochromis niloticus were tested for their probiotic effect on goldfish. The isolates were able to degrade short chain synthetic C6-HSL in vitro and hampered violacein production by Chromobacterium violaceum. They were susceptible to all the five antibiotics tried. The isolates grew well at pH 3.0–7.0, were resistant to high level of bile salts (0–0.9%) and 0.5% of phenol. They also exhibited high degree of auto-aggregation and co-aggregation, confirming that they possessed good probiotic attributes. Disease resistance in goldfish against Aeromonas hydrophila infection was assessed with 28 different combinations of probiotic mixtures of the four bacterial strains:L. plantarum QQ8, L. casei QQ10, Enterococcus faecium QQ12 and Bacillus thuringiensis QQ17 (QQ12 and QQ17 were previously isolated in our laboratory) by using the statistical approach of response surface methodology (RSM). The ability of goldfish to resist A. hydrophila infection was higher in probiotic combination fed treatments than that fed with commercial feed alone. The highest survival was observed in gold fish fed diet incorporated with the combination dose of 103 CFU/g feed of L. plantarum QQ8, 102 CFU/g feed of L. casei QQ10, 102 CFU/g feed of E. faecium QQ12 and 103 CFU/g feed of B. thuringiensis QQ17. The corresponding desirability score was almost 1. Goldfish showed 91.7% survival when challenged with A. hydrophila. This study demonstrated the potential of multi-species quorum quenching probiotics as feed additive in aquaculture to control bacterial diseases and use of response surface methodology in determining the optimum combination of probiotic mixture.
- ItemSynthesis and characterization of carbon nanodots from jellyfish(Elsevier, 2022-04-28)In a study which is first of its kind, florescent carbon nanodots (CNDs) were synthesized from jellyfish harvested off Cochin Sea using hydrothermal carbonization method. The synthesized CNDs were characterized by different techniques including, Ultraviolet–visible spectroscopy, Fluorescence spectroscopy, Fourier-transform infrared spectroscopy (FTIR), Differential scanning calorimetry (DSC), Atomic force microscopy (AFM), Transmission electron microscopy (TEM) and zeta potential. FTIR spectroscopic results showed that the CNDs were rich with C––O and C-O groups. Microstructure examination of CNDs using AFM and TEM, revealed the spherical shape of CNDs with about 50 nm diameter. A nylon net surface treated with 1% of CNDs shows good fluorescence under the UV light source. CNDs can have potential application in the area of tracing abandoned, lost and discarded fishing gear (ALDFG) in ocean and also in studying the fish behaviour either as attractant or deterrent.
- ItemTemperature, salinity and body-size influences depuration of heavy metals in commercially important edible bivalve molluscs of India(Elsevier, 2022-08-01)The effect of temperature, salinity and body-size on depuration of naturally accumulated heavy metals in clams, mussels and oysters harvested from Ashtamudi and Vembanad estuaries of Kerala, India were investigated using a static depuration system. Before depuration, the concentrations of heavy metals such as Ni, Co, Fe, Mn, Cu, Pb and Zn were analysed and it was found that the Fe, Zn, Cu and Pb contents in all the three bivalve molluscs were above the prescribed limit which poses a significant health risk to bivalve consumers. To protect consumer food safety, depuration experiments were conducted at varying temperatures, salinities and body-sizes. The clams, mussels and oysters depurated under the room temperature depuration system (RTDS) showed a better reduction of heavy metals compared with low-temperature depuration system (LTDS). ANOVA showed clams and mussels depurated at RTDS significantly (p < 0.05) reduced the heavy metals than LTDS. However, there was no significant (p > 0.05) difference in oysters between RTDS and LTDS. Further, clams and mussels depurated at low salinity (15-psμ) showed high resistance against Pb reduction. But, all the heavy metals, particularly, Pb, Fe, Zn and Cu were effectively removed at higher salinity depuration (25-psμ and 35-psμ). Moreover, irrespective of the body-size of clams, mussels and oysters used for depuration, a significant (p < 0.05) reduction in all metals (Ni, Co, Fe, Mn, Zn, Pb and Cu) was observed. Relatively, the medium-size bivalves showed higher reductions compared to small-size bivalves. Based on the experiments conducted, we recommend 48 h depuration using the static system under room temperature (30 ± 1 ◦C) with a salinity range of (25–35 psμ) using medium-size bivalves (clam>30 mm; mussel >45 mm, and oyster >65 mm length) as optimum conditions for producing safe bivalves for consumption in the tropics.
- ItemPhoto-protective effect of cuttlefish ink melanin onhuman hair(Wiley, 2021-08-07)The photoprotective properties of exogenous melanin extracted from cuttlefishink on human hair was assessed. Melanin extracted from cuttlefish ink wasapplied on black hair and irradiated using a solar simulator. The extent ofphotodegradation was determined by microstructural, morphological andmechanical testing. The UV–Vis spectra of melanin extracted from cuttlefishink indicated strong absorption at UV region and moderate absorption in visi-ble region. The melanin-coated samples indicated significant protection to haircuticle against UV radiations, as indicated by microscopic images (SEM). Con-versely, visible cracks were evident on uncoated hair shafts, when exposed toUV-radiations. Also, the melanin-coated hair samples indicated negligiblealterations in disulfide linkages, free sulfhydryl group content, water retentionindex and swelling index on UV exposure, as compared to that of uncoatedsamples. Similarly, the mechanical strength of the uncoated hair fibers was farcompromised by UV irradiation compared to that of melanin-coated hairfibers. The observations of the present study postulate cuttlefish melanin as apotential photoprotective agent in hair-care formulations, which is otherwiseconsidered as a process discard from cephalopod processing industry.
- ItemHeat penetration characteristics and quality of ready-to-eatshrimp in masala (Litopenaeus vannamei) in flexible retortablepouches(Wiley, 2021-02-22)Shrimp in masala is a famous south Indian dish prepared using white leg shrimp(Litopenaeus vannamei) in the culinary style. The present investigation was aimed tooptimize different F0 values of the shrimp in masala packed in flexible retortablepouches. The product was thermally processed at different lethality and heat pen-etration characteristics indicating similar heating and cooling lag factor. F h value was24.5 and 23 min for the product processed at Fo values of 8 and 9 min, respectively.Total processing time was 37.11 and 39.88 min, respectively, for Fo 8 and 9 min. Cookvalue of the processed product was 84.07 min for Fo 8 min and 92.41 min for Fo 9 min.Except cohesiveness, all other instrumental texture parameters showed significantdifferences (p < .05) between the two samples. Based on the organoleptic evalua-tion, product processed at Fo 8 min was rated better