Technological aspects of preservation and processing of edible shell fishes III. Factors influencing the keeping quality of crab (Scylla serrata) during freezing and frozen storage

The possible factors leading to the loss of flavour and general quality of crab during freezing and frozen storage have been studied. The preprocess ice storage condition of the raw material was found to be one such important factor while the fresh frozen crab meat remained in good organoleptic condition for about 51 weeks at -23°C, the 7 days iced material held frozen was found to have a shelf life of about 21 weeks. The fall in myofibrillar protein noted during frozen storage together with the loss of myosin ATPase activity correlated well with the loss of organoleptic qualities.

Faecal streptococci in fresh frozen shrimp

Present limit of faecal streptococci as 100/g in fresh frozen shrimp was found to be too strict a standard commercially prepared products. Statistical analysis of the data collected indicates that fixing the maximum permissible limit as 1000/g will be a more workable proposition.

Technological aspects of preservation and processing of edible shell fishes IV. Comparative efficiency of different glazes in the preservation of frozen crab meat

The present work was undertaken to enlighten upon the comparative efficiency of different glazes in improving the quality of frozen crab meat (Scylla Serrata).

Bacterial aspects of quality of phosphate treated frozen prawns

Changes in physical, organoleptic and biochemical characteristics of phosphate treated prawns and frog legs during storage have been studied in detail by Mathen and Pillai, (1970). Adoption of the recommended method by the industry in the freezing of prawns made it necessary to assess the influence of such treatment on the bacterial quality. This aspect assumes more importance in view of the proposed compulsory bacterial standards for raw frozen prawns. This note gives an account of the results on the influence of phosphate treatment on bacterial quality of raw frozen shrimp meat.

Lipid hydrolysis in mackerel (Rastrelliger kanagurta) during frozen storage

The hydrolytic changes in the lipids of mackerel (Rastrelliger kanagurta) during storage at -l8°C were studied with a view to understand the factors involved in the formation of free fatty acids. Only the phosphorylated fraction did undergo hydrolysis at an appreciable rate. It was found that the free fatty acid production was mainly associated with the phospholipid hydrolysis. As regards the triglycerides and unsaponifiable matter, there was no significant change in levels during frozen storage.

A statistical study on weight loss in frozen prawns

This paper deals with an extensive study conducted to estimate the extent of weight loss in frozen prawns. The weight Joss varied from 7 to 12% in peeled and deveined (PD), 5 to 7% in headless (HL) and about 7% in cooked and peeled (CP) prawns from the date of processing to the date of inspection, normally within two weeks. To compensate the weight loss nearly 11% of excess material is being added with every frozen block resulting in an average annual loss of Rs. 2.68 crores in foreign exchange. The relevant data pertain to the period 1971 to 1973 and the annual average loss was estimated for the ten years ending 1973.

Iced and frozen storage of squid (Loligo sp)

The iced and frozen storage characteristics of squid (Loligo sp.) are discussed. Squid can be kept in ice in an acceptable condition for a maximum period of 2 days. Frozen squid can be stored for a maximum period of 15 weeks at -l8°C, which can be extended up to 19 weeks by suitable treatment.

Investigations on long distance transportation of fish 1. Transportation of frozen fish from Cochin to Calcutta

Oil Sardine (Sardinella longiceps), mackerel (Rastrelliger kanagurta), cat fish (Arius sp.), threadfin bream (Nemipterus japonicus) and ribbon fish (Trichurus sp.) were frozen in glazed/unglazed blocks, packed in expanded polystyrene (EPS) insulated plywood boxes with and without additional ice and despatched in uninsulated parcel vans of trains from Cochin to Calcutta. The consignments reached the destination in excellent condition and were readily disposed off.

A biochemical test for the distinction of fresh fish from frozen and thawed fish

It is observed that the freezing and thawing of fish leads to increase in the total activity of aspartate aminotransferase (AAT) in tissue fluid due to the release of the bound form of mitochondrial enzyme. Electrophoresis of the tissue fluid of fresh unfrozen fish shows only a single fast-moving band of AAT in the anodic region whereas frozen and thawed fish shows an additional slow-moving band corresponding to mitochondrial AAT in the cathodic region. The method can be adopted to distinguish fresh fish from frozen and thawed fish.

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.

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.

Studies on frozen storage of minced fish from threadfin bream

Minced fish prepared from threadfin bream (Nemipterus japonicus) was frozen as blocks, packed in polythene lined waxed cartons and stored at -23°C. The changes taking place during storage were followed. There was good correlation between the organoleptic quality, extractability of protein, cook drip loss and weight loss on thawing. The frozen minced fish was acceptable up to 28 weeks under frozen storage.

Denaturation of Labeo rohita (Rohu) actomyosin on frozen storage: preventive effect of carbohydrates

The preventive effect of sucrose and glucose on the denaturation of frozen rohu actomyosin at -20°C for 7 weeks was examined using an in vitro test model. The rate of denaturation was followed by estimating percentage salt extractability, Ca¹²+ ATPase activity and the clearing response test. Sucrose and glucose showed cryoprotective action for all concentration of actomyosin. Higher actomyosin concentration was preserved better than lower concentration. Post-rigor actomyosin was preserved to a greater extent than pre-rigor actomyosin. Correlation between percentage salt extractability and enzyme activity could not be observed in all samples of frozen actomyosin studied.

Effect of incubation period on plate count of raw ices and frozen fish

The total viable counts were estimated in one hundred and sixty five samples of raw, iced and frozen fish using incubation periods of 24, 48, 72 and 96h. For raw fish, 24h and for iced and frozen fish 48h incubation of the plates were found to be adequate. Variation between samples was significant at 1% level for raw iced and frozen samples.

Denaturation of Labeo rohita (rohu) actomyosin on frozen storage: preventive effect of dicarboxylic acids

The preventive effect of fumarate, maleate, tartrate and oxalate on the denaturation of frozen rohu actomyosin at -20°C in 0.7 M KCl for 7 weeks was examined using an in vitro test model. The rate of denaturation was followed by estimating percentage salt extractability, Ca²+ ATP-ase activity and the clearing response test. Fumarate, maleate and tartrate showed cryoprotective effect for higher concentration of pre-rigor rohu actomyosin of 10 mg/ml and 20 mg/ml. At actomyosin concentration of 6 mg/ml, maleate and tartrate showed some preventive effect whereas fumarate enhanced denaturation. Oxalate showed poor cryoprotective action. Post-rigor rohu actomyosin was preserved frozen without denaturation to a greater extent than pre-rigor actomyosin.