Some changes in the physical qualities of muscle lipid of the freshwater murrel, Ophicephalus striatus (bloch.) during storage

The present communication reports the changes in the specific gravity, coefficient of viscosity, fluidity and surface tension of the muscle lipid of O. striatus, a common freshwater murrel, when stored at room temp (32 ± 2°C) The specific gravity of muscle lipid was found to rise from 0.894 to 0.912 during the first 25 days of storage but registered the highest (0.925) when stored for 50 days. Surface tension seemed to rise with the duration of storage. This was, presumably, due to an increase in the forces with which the molecules in the surface of the lipid tended to compress the molecules below to the smallest possible volume. During the period of storage marked changes seemed to occur in the direction of an increase in the value of the coefficient of viscosity and a reciprocal decline in the fluidity. Evidently, the observed increase in the viscosity seemed to be the result of increased internal friction between different molecular layers of the lipid, whereas a decline in the fluidity was perhaps the consequence of its inverse correlation with the coefficient of viscosity.

Identification of native American founder mtDNAs through the analysis of complete mtDNA sequences: Some caveats

In this study, a detailed analysis of both previously published and new data was performed to determine whether complete, or almost complete, mtDNA sequences can resolve the long-debated issue of which Asian mtDNAs were founder sequences for the Native American mtDNA pool. Unfortunately, we now know that coding region data and their analysis are not without problems. To obtain and report reasonably correct sequences does not seem to be a trivial task, and to discriminate between Asian-and Native American mtDNA ancestries may be more complex than previously believed. It is essential to take into account the effects of mutational hot spots in both the control and coding regions, so that the number of apparent Native American mtDNA founder sequences is not erroneously inflated. As we report here, a careful analysis of all available data indicates that there is very little evidence that more than five founder mtDNA sequences entered Beringia before the Last Glacial Maximum and left their traces in the current Native American mtDNA pool.

Distribution of phosphorylase in some fish and shell fish

Phosphorylase content in the muscle of some fish and shell fish were estimated. Jew fish (Johnius dussumeri) and 'sea naran'(Penaeus indicus) recorded the highest enzyme content among the fish and shell fish studied. As phosphorylase is the key enzyme in glycogenolysis, which is the energy source of fish for muscular activity, the possible role of phosphorylase content as an index of muscular capacity and post-mortem autolysis is discussed.

Nucleotide degradation and production of hypoxanthine in some Indian marine and freshwater fishes

Changes in nucleotides and production of hypoxanthine in rohu (Labeo rohita), mrigal (Cihhrina mrigala) and common carp (Cyprinus carpio) during storage at 2-4°C were examined. Differences were observed between common carp and others. Production of hypoxanthine in pomfret (Stromateus argenteus), cat fish (Arius macronotacanthus), shark (Scoliodon spp.), seer fish (Scomberomorus guttatus), ray fish (Dasyatis imbricata) and prawns (Parapenaeopsis stylifera) was examined during storage at 2-4°C and -28°C. At 2-4°C hypoxanthine increased regularly but at -28°C there was no increase during storage over 28 weeks.

Some further considerations in the development of an experimental design for sensory evaluation of fish quality

An experimental procedure along with a method of analysis to judge the suitability of an individual to be included in a taste panel is described. The procedure is based on comparison of the organoleptic scores assigned by the individual to pairs of fish samples whose qualities are known and a set of physical measurements of the same samples. Fisher's Exact Probability Test provides a criterion for the judgement.

The effect of salinity on some endocommensalic ciliates from shipworms

The ciliates, Nucleocorbula adherens, Boveria teredinidi, Trichodina balakrishnia, Thingmozoon fencheli and Nyctothereus marina, live inside the mantle cavity of the shipworms in the estuaries and backwaters of the south-west coast of India. Seasonal incidence and relative abundance of these ciliates showed that they were more abundant during the low saline than the high saline periods. Even though these ciliates can endure higher salinities through gradual acclimatization of their habitat it was found that they prefer low salinity for active growth and healthy existence.

Some fungal infestations of dried fishes in Cochin markets

Dried fish constitutes a regular item of trade in India, particularly in the interior parts far away from the sea and rivers. The poor section of the society is the main consumer. The quality of dried fish never receives much attention at any stage of processing (drying) and storage. A good amount of these fish is discarded during drying due to fungal growth to avoid the danger of mycotoxin production. A survey of the dried fish from the Cochin markets had revealed that they do carry fungal infestations and their chances of mycotoxin production cannot be ruled out as the strains of Aspergillus flavus, Aspergillus ochraceus and Fusarium spp. have been isolated.

Raw material supply to shrimp freezing plants: some significant aspects

The shrimp processing plants located at any particular place receive their raw material supplies from local and outside centres. The raw material received, the form in which it was received, the relative contribution by local and outside centres and the seasonal variation in the supplies were studied with respect to the shrimp processing plants located at three places - Cochin, Veraval and Kakinada.