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.

Studies on frozen storage characteristics of sole fish Cynoglossus macrolepidotus

Fresh sole fish (Cynoglossus macrolepidotus) was quick frozen at -40°C and stored at -18°C. Shelf life was evaluated by following biochemical, bacteriological and organoleptic changes occurring during storage. Rapid decrease was noted in the water extractable nitrogen and salt soluble nitrogen fractions. Samples of frozen sole fish remained in acceptable condition for 20 weeks.

Preparation and storage of cutlet from low-priced fish

Cutlets have been prepared from the minces of lizard fish (Saurida tumbil), threadfin bream (Nemipterus japonicus), jew fish (Johnius dussumieri) and miscellaneous fish. The storage characteristics of cutlet (both raw and flash fried) at 4°C, -8°C and -20°C were studied. Cutlets prepared from the minced lizard fish showed the highest acceptability. Flash fried cutlets were found to be superior in quality compared to raw cutlets. The raw cutlet had storage life of 6 days, 11 weeks and 19 weeks at 4°C, -8°C and -20°C respectively and flash fried cutlets had a shelf life of 22 weeks at -20°C.

Changes in the muscle of three Indian major carps during frozen storage

Chunks of Labeo rohita, Cirrhinus mrigala and Catla catla wrapped in polythene film were stored at -8 to -10°C in the freezer cabinet of the refrigerator. It was found that L. rohita and C. mrigala were acceptable up to 33 days and C. catch up to 35 days. Total volatile base nitrogen, free fatty acids and degree of sponginess of the samples showed increasing trend during frozen storage.

Quality deterioration in tilapia during storage in refrigerated brine

During storage of Tilapia nilotica in refrigerated brine at 4°C, the whole (ungutted) fish had higher levels of free fatty acid and spoiled faster than the gutted fish. The shelf life of whole fish was 16 days and that of gutted 28 days; these values are, at least, as good as those reported for ice storage. Flavour of the cooked fish appeared to be the quahty-hm1tmg factor reducing the shelf-life of gutted tilapia to 28 days even though the raw gutted fish was judged acceptable, after 31 days retaining 65-70% freshness.

Effectiveness of EDTA dips on the shelf-life of oil sardine (Sardinella longiceps), mackerel (Rastrelliger kanagurta) and prawn (Metapenaeus dobsoni) in iced storage

Fresh oil sardine, mackerel and prawn were dipped in 0.1% and 1% solutions of Na sub(2)EDTA, and stored in ice. Their storage-life was assessed by bacteriological, chemical and sensory methods. Even though EDTA treatment controlled the increase in bacterial counts and reduced TMA and TVBN production in oil sardine and mackerel, the consequent beneficial effect was not realised because of the deterioration of fat in these fishes, leading to rancidity. But, for prawn stored in ice, a dip in 1% solution of Na sub(2)EDTA enhanced the shelf-life by at least 8 days over the untreated control. EDTA absorbed by the muscle of fish and prawn during dip in Na sub(2)EDTA solution is not completely removed during their iced storage for 25 days.

Succession of bacterial genera during iced storage of three species of tropical prawns, Penaeus indicus, Matapenaeus dobsoni and M. affinis

The native bacterial flora of ocean fresh tropical prawns, Penaeus indicus, Metapenaeus dobsoni and M. affinis was more or less similar, mainly consisting of Pseudomonas, Acinetobacter, Moraxella and Arthrobacter. A definite succession of bacterial genera during iced storage was observed in these prawns. As the day of ice storage increased, the proportion of Acinetobacter and Moraxella also increased considerably and constituted 70-78% of the flora at the time of spoilage. Spoilage by Pseudomonas was very not significant in prawns under iced storage.

Preservation of Sardinella longiceps in iced and chilled seawater. Part 1 - Changes during storage with particular reference to bacterial load and nitrogenous compounds

Oil sardines in prime condition were subjected to onboard chilling. Two lots were chilled in CSW (samples C and CI), a third lot was chilled in crushed ice (sample I) and a fourth lot left not iced on deck (Sample AI). Upon landing sample AI was iced and sample CI was removed from the CSW and iced. All the four samples were kept in a chilled room for storage studies. The fish chilled and stored in CSW recorded the least, and the fish subjected to delayed icing, the highest values for all the indices of spoilage namely, free amino nitrogen, trimethylamine (TMA) and total volatile base nitrogen (TVBN). The total psychrophilic bacterial number also showed a similar trend. The organoleptic assessment of the cooked samples revealed C I, CI, AI to be the order of preference throughout the storage. This assessment was found to hold good for the rest of the parameters as well. The CSW held fishes were found to be distinctly superior to the iced ones for the first five days of storage. Such a marked prevalence in quality for five days would suffice for the fish to fetch a premium in the market over other landings of the same fish whether chilled or not chilled. Chilling on board in CSW and icing the same after landings, did not show encouraging results.

The effect of washing on the quality of minced catfish during frozen storage

The effect of washing minced catfish in water, sodium chloride solution (1%) and ascorbic acid solution (0.1%) in improving the quality and frozen shelf-life has been studied. Washing improved the colour and reduced the non-protein nitrogen contents and extractable nitrogen. Denaturation was more in samples washed in salt and ascorbic acid solutions. Rancidity as measured by PV and organoleptic studies showed significant reduction in washed samples. The frozen storage life was significantly enhanced by washing.

Development and storage characteristics of dehydrated salt mince from low priced fish

The study showed that less initial moisture with high salt content will be the best condition for enhanced storage life of dehydrated salt mince. Between sample I (10% salt per meat weight) and sample II (15% salt per meat weight) the latter was comparatively better in colour, odour and longer shelf-life. At room temperature the dehydrated salt mince has not showed any increase in total bacterial count. It is also found that the storage life of the salt mince can be enhanced to a significant extent by lowering the moisture content to below 10% and increasing the salt content to above 30%. Peroxide value, free fatty acid value, total volatile nitrogen and trimethylamine registered gradual increase during storage at room temperature for all the three samples. Among the three samples, the sample treated with 0.1% citric acid and 0.125% butylated hydroxy anisole was comparatively better in appearance and showed less rancidity as indicated by TBA values, up to a period of 15 weeks and thereafter all the three samples were almost similar in storage characteristics. Hence, the treatment with citric acid and B.H.A. has apparently not much significance in improving shelf-life and quality of salted dehydrated fish mince.

Frozen storage studies of composite fish mince drom dhooma (Sciaenid sp.) and lactarius (Lactarius lactarius)

Fish minces from dhoma and lactarius were mixed in the ratio of 40:60 respectively, and quick frozen along with individual minces at -40°C and stored at -20°C. Shelf life was evaluated by following biochemical, physical and organoleptic changes occurred during storage up to 44 weeks. Rapid decreases were noted in water soluble nitrogen and salt soluble nitrogen fractions during the initial period of 16 weeks. A good correlation was observed between changes in salt-soluble nitrogen and organoleptic evaluation. The minces were in good and acceptable condition up to 32 weeks of storage.

On the ice-storage characteristics of Catla catla and Labeo fimbriatus

The ice-storage characteristics of Catla catla and Labeo fimbriatus are reported. Muscle pH, moisture, total volatile nitrogen, alpha amino nitrogen and peroxide value and also the changes in total bacterial count are studied. C. catla and L. fimbriatus both could be stored in ice for 18 days.

High temperature processing of fish sausage 3. - Studies on some of the storage characteristics

The proximate composition of the high temperature processed fish sausage was found to be 14.56% protein, 4.65% fat, 69.14% moisture, 2.12% ash and 8.12% carbohydrate. The quality of the product during storage was assessed on the basis of the changes observed in the physical, chemical and microbiological parameters. The results of the different tests such as pH, volatile base nitrogen (VBN), trimethyl amine nitrogen (TMA-N) and jelly strength are summarized and discussed. The total bacterial load increased gradually during storage but was not proportional to the initial load.

Relationship between water, lipid and protein in the muscle, liver and gonad in a freshwater fish Puntius filamentosus (Val.)

Details are given of a study investigating the relationship between water, lipid, and protein in Puntius filamentosus. Percentage compositions in the muscle, liver and gonad of fish specimens from Lake Vellayani in India are given, showing the fluctuations which occur during maturation.