Studies on blue discolouration in canned body meat of crab (Scylla serrata)

Blue discolouration met with in the canned body meat of crab (Scylla serrata) was due to copper content exceeding 1.8 to 2.0 mg/100g on dry weight basis. Bleeding the cleaned carcasses of crab thoroughly in running water brought down the copper content below this level and blue discolouration prevented. Addition of copper ions to the thoroughly bled crab meat to raise the copper content above this level caused discolouration. The incidence of blue discolouration was independent of the freshness of the animals used. Citric acid in high concentration prevented blueing to some extent, but is not advisable as texture and flavour were adversely affected.

Influence of sex, spawning, starvation and water temperature on fatty acid composition in Tilapia mossambica

The influence of sex, spawning, starvation and water temperature on the fatty acid composition of Tilapia mossambica has been studied. Tilapia egg lipid was found to have unusually high percentage of C sub(22:6) fatty acids (9.09%) compared to body and intestinal lipids. The C sub(16:1) acid was much less in the egg lipids (3.5%) whereas it was 11% in the body lipids. There was no significant difference in the fatty acid composition of body and intestinal lipids of male and female tilapia. Starvation caused the presence of high content of lower fatty acids (C sub(6), C sub(8), C sub(30), C sub(12) and C sub(33)) in the body lipids. Water temperature also influenced the fatty acid composition of Tilapia; the difference was more significant in body lipids than in intestinal lipids.

Comparative study of the nutrient content of fish and shell fish

The amino acid, mineral and proximate composition of mullet (Mugil oeur), mackerel (Rastrelliger kanagurta), crab (Scylla serrata) and prawn (Penaeus indicus) are reported. The data are used for comparing the nutritional quality of the fish and shell fish. Further, the amino acid composition is screened for their adequacy to meet the FAO/WHO recommended pattern of essential amino acids.

Selection of bacterial flora in the Chlortetracycline treated oil sardine (Sardinella longiceps), Indian mackerel (Rastrelliger kanagurta) and prawn (Metapenaeus dobsoni) during ice storage

The native flora of oil sardine and mackerel consisting of Pseudomonas spp; Moraxella spp., Acinetobacter spp. and Vibrio spp. underwent significant changes during ice storage. At the time of spoilage, Pseudomonas spp. were predominant. CTC treatment significantly reduced the Pseudomonas spp. in the initial stages of storage; but later Pseudomonas spp. reasserted and constituted the bulk of the spoilage flora. In prawn, the native flora was comprised of Pseudomonas spp., Acinetobacter spp., Moraxella spp. and Vibrio spp. At the time of spoilage a heterogeneous flora, consisting of Pseudomonas spp; Moraxella spp. and Acinetobacter spp. predominated. CTC treatment significantly changed the flora of prawns. During spoilage, Pseudomonas predominated in CTC treated prawns.

On the vertical distribution of seers and other commercially important fishes in the surface drift nets

This note highlights the author's attempts to determine the vertical height for catching seers (Scomberomorus sp.) and other commercially important fish off Kakinada coast.

Water soluble nitrogenous component from squilla (Orato squilla nepa)

A water soluble hygroscopic powder has been isolated from squilla in good yield, ranging from 3.5 to 5.0% of the fresh raw material, by a simple direct method. The process consists of homogenising squilla with an equal quantity of water, removal of chitinous matter from the slurry by filtration, heating the filtrate at 0.7 kg/sq.cm steam pressure for 15-20 minutes, removal of the precipitated protein by filtration and concentration and final drying in vacuum of the filtered cooled liquor. The pale brown powder so obtained consists mainly of peptones and proteoses and has been found to be comparable to BDH peptone for growth of bacteria, ability to serve as source for tryptophan for indole production and to provide substrate for the production of hydrogen sulphide. Comparative studies have been made on similar water soluble fractions from two species of prawns, namely, Metapenaeus affinis and Parapenaeopsis stylifera.

Report on the occurrence of one subspecies of Scylla serrata (Forskal) in Cochin backwaters

The taxonomy of the mud crab, Scylla serrata has become a topic of interest. Alcock (1899) described this species from Indian waters. It was considered that under the genus Scylla, only one species, namely, Scylla serrata was valid. But Estampador (1949) revised the genus and reported the occurrence of four sorts, Scylla serrata, S. tranquebarica, S. oceanica and a variety S. serrata, var paramarnosain in Philippine waters. He established his claim based on the morphology such as colouration, relative length of chelae and also on the cytological events during gametogenesis. Serene (1952) pointed out that two distinct categories under this genus were demonstrable on the basis of colouration. But Stephenson & Campbell (1960) concluded them as only synonyms, but pointed out the need for further investigations.

Survey on the idle capacity of fish processing (freezing) plants in India - 2. East coast

The extent of idle capacity in the fish processing (freezing) plants in the east coast of India estimated by stratified random sampling and the factors responsible for the same are reported. The estimates of idle capacity of fish processing plants in the east coast for the years 1978 and 1979 were respectively 75.9% and 72.5% on the basis of 250 working days per annum and double shift per day. The percentage errors of estimates worked out to 6.9 for 1978 and 4.7 for 1979. The corresponding figures were worked out on the basis of 200 working days also. Substantial under-utilisation of plants in all the maritime states in the east coast accounted mainly to non-availability of raw material, high cost of production, shortage of power, scarcity of ice and potable water during peak season and frequent labour troubles.

Experimental trawling in Hirakud reservoir

Results of trawl fishing experiments conducted in Hirakud reservoir are discussed. Trawling has been found to be efficient than conventional gear in removing predators and trash fishes especially of the bottom. This method can be of much help in controlling the proliferation of such fishes in many Indian reservoirs.

Biochemical changes of fish fingers held at frozen storage

The frozen storage characteristics of fish fingers made out of two different species, differing in lipid content for a period of six months are outlined. The study reveals that the lipid content of the fish meat used for making fish fingers influences the storage pattern in terms of the chemical parameters like peroxide value, thiobarbituric acid value and free fatty acids. The introduction of monosodium glutamate has improved the flavour of the fish fingers. Further, the application of batter on the fish fingers imparted some protective effect in the case of semi-fatty fish.

Processing clam meat into pickles

Methods have been worked out for the production of pickles from clam (Velorita sp.) meat. The bacteriological quality of the clam meat at different stages of processing was studied. The clam pickles packed in glass bottles and sealed air tight remained in good condition for six months at ambient temperatures.

Studies on frozen storage of ghol (Pseudosciaena diacanthus)

Investigations were carried out on the frozen storage of ghol (Pseudosciaena diacanthus) in the form of fillets. The results indicated that ghol fillets stored at -l8°C remained in a highly acceptable condition up to 20 weeks. However, after this stage, the acceptability steeply declined.

Bacterial flora of EDTA treated oil sardine (Sardinella longiceps), Indian mackerel (Rastrelliger kanagurta) and prawn (Metapenaeus dobsoni) in ice storage

The native flora of fresh oil sardine and mackerel consisted mainly of Pseudomonas spp., Moraxella spp., Acinetobacter spp. and Vibrio spp. During spoilage in ice, nearly 75% of their bacterial flora belonged to Pseudomonas spp. alone. But Na sub(2) EDTA treatment reduced the proportion of Pseudomonas spp. considerably and the major bacterial groups at the time of spoilage were Moraxella spp. and Acinetobacter spp. In the case of fresh prawn, the native flora was constituted by Pseudomonas spp., Moraxella spp., Acinetobacter spp. and Vibrio spp. At the time of spoilage of prawn in ice, Moraxella spp. and Acinetobacter spp. predominated, together constituting 74% of the total population. Na sub(2) EDTA treatment did not alter significantly the spoilage flora of prawns. Moraxella spp. and Acinetobacter spp. accounted for 86% of the spoilage flora in ice storage of Na sub(2) EDTA treated prawns.

Pickled products from green mussel

Methods of preparing different types of delicious ready to serve pickled products from green mussel (Perna viridis) and a comparative study of their storage characteristics are reported. Of the three types of products, namely, dried and pickled, fried and pickled and light smoked and pickled, the last one had the best shelf life. The optimum conditions of drying and smoking for preparing such type of pickles are also reported.

Ice storage studies of Kati (Pellona sp.)

Studies were carried out on the effect of ice storage on the composition of kati (Pellona sp.). On the basis of biochemical, bacteriological and organoleptic valuations, it was observed that kati can be stored in ice for a period of 9 days without appreciable loss in overall quality.