Quality problems in fish processing

Various problems associated with the quality of the fishery products like spoilage, discolouration, microbiological problems, etc., are outlined. The reasons and remedial measures are discussed. The importance of proper handling, processing and hygiene is stressed

Measurements of Indoor Radon Levels in India using Solid State Nuclear Track Detectors: Need for Standardisation

Solid-state nuclear track detectors are being used to obtain the time integrated concentration levels of indoor radon/thoron and their daughters. This technique is preferred for taking such measurements in dwellings. Such measurements are important as the radiation dose to human beings due to indoor radon constitutes more than 50 per cent of the total dose including that received from the natural sources. Normalisation is necessary to obtain a representative value of the effective dose equivalent to the population. Indoor measurements carried out by several laboratories all over the country show that the indoor radon levels vary from 1.5 to about 2000 Bq m/sup -3/, while the normal level is in the range of 10 to 60 Bq m/sup -3/. It is rather difficult to compare the levels since the exposure conditions, the period of measurements and the calibration techniques used are not standardised. The present paper discusses the measurements of indoor radon in India by various groups and the important problems associated with the standardisation of these measurements. The standardisation procedure and the calibration set-up developed at this laboratory are also presented

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Not AvailableThe physicochemical properties of muscle proteins extracted from two different weight groups (500 and 1500 g) of barracuda (Sphyraena jello) are discussed. Solubility of sarcoplasmic protein (SPP) from groups I and II fishes were 107 and 167.18 mg per g, respectively. The myofibrillar protein (MFP) concentration was significantly higher in group II. The concentration of reactive sulphydryl group and Ca2+ ATPase activity of MFP were higher in group II fishes than in group I fishes. Surface hydrophobicity of MFP was noticeably higher for group I fishes compared to the other group. High emulsion activity index (EAI) was noticed for group I fishes. EAI of SPP increased but that of MFP decreased with increase in protein concentration in both the fishes. MFP from group I fishes showed better emulsion stability (ES) and the ES showed concentration-dependent increase in both groups for both SPP and MFP. Foam expansion was higher in group I fishes, but foam volume stability (FVS) of both the groups did not show any significant difference. Viscosity, water holding capacity (WHC) and gel strength (GS) were higher for group I fishes. Electrophoretogram of SPP and MFP of both the groups show difference in band pattern indicating that proteins expressed during various stages of growth vary.Not Availabl

Indoor 222Rn and 220Rn concentrations and doses in Bangalore, India

222Rn and. 220Rn levels have been measured using passive detector technique by employing time integrated solid-state nuclear track detector-based dosemeters in various types of houses at 10 different locations in and around Bangalore Metropolitan, India. The measured geometric mean concentration values of. 222Rn and. 220Rn levels in 200 dwellings of different types of construction were found to be 32.2±1.6 and 21.4±1.0 Bq m. -3, respectively. The dose rate received by the population of Bangalore ranged between 0.2 and 3.5 mSv y. -1 with an average and the geometric mean of 1.14±0.05 and 1.06 mSv y. -1, respectively. Overall, the result does not show much significant radiological risk for the inhabitants and the. 222Rn levels are well within the limits of global average concentration of 40 Bq m. -3. However, the. 220Rn levels observed were found to be higher than the global average of 10 Bq m. -3. © The Author 2012. Published by Oxford University Press. All rights reserved

The spatial and volumetric variations of radon in Bangalore Metropolitan, India

Radon levels have been measured in houses at ten different locations of Bangalore City, India. The study was focused on the basis of quality of construction, age of building and room volume. Solid state nuclear track detectors were used for measuring the concentrations. The average spatial values of 222Rn and 220Rn concentrations were found to be 33.4 ± 6.1 and 21.6 ± 2.5 Bqm-3, respectively. However, the volumetric concentrations were ranged between 4.0 and 93.0 Bqm-3. The annual dose rate due to 222Rn, 220Rn and their progenies for the population in the studied location ranged from 0.5 to 3.5 mSvy-1. It is alarming that the dwellers of lower volumes receive a relatively higher dose rate and the result shows significant radiological risk. The magnitude and its effects of doses are discussed in detail. ©2011 Academic Journals

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Not AvailableThe effect of iced storage on functional properties viz. solubility, emulsion activity index (EAI), viscosity, foaming, of muscle proteins from fresh water fish Rohu (Labeo rohita) was evaluated. Myofibrillar protein (MFP) solubility showed an increasing trend up to 11 days of storage followed by a decrease. Solubility of sarcoplasmic protein (SPP) showed a decreasing trend through out the storage period. A 44% drop in emulsion activity index (EAI as m2/g) was observed in the case of MFP on storage. MFP showed foam volume stability (FVS) of 94% and a 22% loss in stability was recorded on the 25th day. Viscosity of SPP remained relatively stable through out the duration of study while that of MFP showed an increasing trend during the first week and then decreased. Influence of protein concentration on different functional properties were also studied. The data are discussed in relation to protein conformational changes as indicated by changes in hydrophobicity, and reactive sulphhydryl groups. Reactive sulphhydryl groups increased gradually attaining a maximum on the 6th day and a gradual decline towards the end. Hydrophobicity of myofibrillar fraction showed a decrease till the 11th day and thereafter it increased gradually. K-value was taken as an index of quality which shot-up from 0.2% to 59.80% during the storage of fish in ice.Not Availabl

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Not AvailableThe conformational and functional characteristics of myofibrillar proteins of fishes from different habitats were investigated. Surface hydrophobicity and Ca2+ATPase activity of the MFP were higher in Mugil cephalus compared with the other fishes studied. Reactive sulphydryl groups were higher in Hypophthalmichthys molitrix. Lowest surface hydrophobicity (6.60) was recorded in MFP extracted from Oreochromis mossambicus. Solubility of MFP was higher for Lutjanus argentimaculatus. Solubility correlated well with the concentration of reactive sulphydryl groups and the surface hydrophobicity of the proteins. Viscosity was higher in H. molitrix and goes well with the reactive sulphydryl groups. Foam expansion and emulsion activity index was high in H. molitrix but foam volume stability and emulsion stability were lower in the MFP of this fish compared with the other fishes. Foam stability emulsion stability and gel strength were higher for Lethrinus lentjan. Protein conformation was found to have profound effect on the functional properties.Not Availabl

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Not AvailableMullet (Mugil cephalus) muscle homogenates were adjusted to different pH ranging from 2 to 12 and the proteins extracted were evaluated for changes in solubility and conformational characteristics viz. surface hydrophobicity and reactive sulphydryl groups. Altering the pH of muscle homogenate to acidic or alkaline increased protein solubility. The hydrophobicity of the proteins increased on exposure to extreme pH indicating unfolding. The reactive sulphydryl groups decreased at acidic and alkaline pH with the lowest at pH 4. When the pH of the muscle homogenates was brought back to the original pH (6.3), the protein solubility was found to decrease. Reactive sulphydryl groups and ANS hydrophobicity of the proteins increased on readjusting the pH resulting in a molten-globule state. The electrophortogram of the samples corresponded well with the observations. Alterations in functional properties of these modified proteins are an area of interest for commercial application.Not Availabl