Electrophoretic studies on serum proteins of oil sardine (Sardinella longiceps) and mackerel (Rastrelliger kanagurta)

Oil sardine blood tests against human typing sera indicated A-positive, A-negative and B-negative. The blood of mackerel is antigenically negative both for A and B. Electrophoretic studies on serum proteins revealed the existence of genetica1ly different groups of oil sardine and mackerel on the south-west coast of India.

Preparation of smoke cured fillets from oil sardine

A method of preparation of smoke cured fillets of oil sardine is described. Various procedural steps like brining, smoking, packaging etc. have been described and the shelf life assessed. Sodium propionate treatment is recommended to enhance storage life; BHA to control rancidity; and thermal treatment to overcome the insect infestation. The product has good consumer appeal.

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.

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.

The bacteriology of oil sardine (Sardinella longiceps) and mackerel (Rastrelliger kanagurta) caught from tropical waters off Cochin. 1 - Quantitative aspects

The total aerobic viable plate counts (TPCs) of skin, gills and intestine of newly caught oil sardine (Sardinella longiceps) and Indian mackerel ( Rastrelliger kanagurta) at four different temperatures, namely 36 ± 1°C, 28 ± 2°C (RT), 8 ± 1°C and 1 ±1°C, are reported. The total plate count at RT of the skin of oil sardine and Indian mackerel were in the range of l0 super(3) to 10 super(7) and 10 super(4) to 10 super(6) per cm², that of gills in the range of 10 super(5) to 10 super(9) and 10 super(4) to 10 super(8) per g and that intestine in the range of 10 super(5) to 10 sueper(9) and 10 super(5) to 10 super(8) per g respectively. The TPCs were markedly affected by the incubation temperature. Incubation at 28 ± 2°C gave the highest count; at 36 ± 1°C and 8 ± 1°C, the counts decreased by nearly 1-2 log cycles from that at RT. Incubation at 1 ± 1°C registered the lowest count. The peak values for bacterial counts of these fishes occurred at different periods of the year.

The bacteriology of oil sardine (Sardinella longiceps) and mackerel (Rastrelliger kanagurta) from tropical waters off Cochin. 2. Qualitative aspects

80% of the flora of skin, gills and intestines of oil sardine and mackerel at isolation temperature 28 ± 2°C consisted of Gram negative asporogenous rods or cocci, belonging to the genera Vibrio, Pseudomonas, Moraxella, Acinetobacter and Flavobacteria/Cytophaga. Nearly 10% of the flora was constituted by Gram positives, Micrococcus and Arthrobacter. Incubation temperature of 36 ± 1°C recovered more Vibrio spp. and Gram positives, while at lower temperatures of 8 ± 1°C and 1 ± 1°C, more Pseudomonas, Acinetobacter and Moraxella spp. were recovered. Significant changes with respect to season were observed in the relative distribution of different genera.

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.

Preservation of Indian oil sardine (Sardinella longiceps) in iced and chilled seawater. Part 2 - Changes during storage with particular reference to salt penetration and lipid deterioration during CSW holding

Oil sardines in prime condition were chilled on board. Two lots were chilled in CSW (samples C & CI), one lot ice (sample I) and a fourth lot was left un-iced on deck (sample AI). Sample AI was iced after landing and sample CI was taken out of the chilled seawater and. iced. All the four samples were kept in a chilled room for storage studies. Sample C, chilled and stored in CSW, recorded a gradual gain in weight and an increase in salt content of the muscle. Presence of salt did not seem to cause any excessive protein denaturation. Salt extractability decreased at a gradual rate in all cases. Presence of salt seemed to wield no noticeable influence on lipid hydrolysis and subsequent peroxidation. Results of chemical and sensory evaluations highlight this. Holding sardines in CSW gave a product of excellent quality for the first four to five days of storage. Beyond the fifth day of storage quality deteriorated rapidly and there was no noticeable superiority for this sample (sample C) over the on board iced fish. This was evident in the sensory evaluation as well. However, a storage life of five days in a readily acceptable state is sufficient for the fish to be disposed in the market at a premium sale price over other landings of the same species.

Effect of chilled sea water storage of oil sardine (Sardinella longiceps) on quality changes during frozen storage

The shelf-life of frozen oil sardine (Sardinella longiceps) can be improved by preserving the fish immediately after catch in chilled sea water before freezing. Delayed icing caused considerable deterioration in quality and reduced frozen shelf-life. Oil sardine preserved in chilled sea water were found to be suitable for freezing up to 5 days whereas iced samples could be frozen only up to 2 days.

Effect of preprocessing storage conditions on the carbonyls of oil sardine

Changes in the total as well as major individual carbonyls of oil sardine muscle during storage at room temperature for 24 h and in crushed ice up to 6 days are reported. Carbonyls extracted with hexane were converted to their 2:4 dinitrophenyl hydrazone (DNPH) derivatives and were separated into major classes by column chromatography on celite/magnesia. Individual carbonyls were then identified by capillary gas chromatography of these derivatives. Though absolute values for carbonyls exhibited wide variations depending upon the degree of freshness, the pattern of changes in the carbonyls during storage of fish under different conditions gave an insight into the influence of carbonyls on flavour. The significance of the findings is discussed.

Effect of cooking and drying on carbonyls of oil sardine

Changes in the total as well as major individual carbonyls of oil sardine during steam cooking, oven drying, sun drying and freeze drying are presented. Carbonyls extracted with hexane were converted to their 2:4 dinitro phenyl hydrazone (DNPH) derivatives and were separated into major classes by column chromatography on celite/magnesia. Individual carbonyls were then identified by capillary gas chromatography of the DNPH derivatives. Dehydration and heating increase the carbonyl production from highly unsaturated fish lipids. The carbonyls produced react with other muscle constituents leading to complex changes. The influence of the mode of dehydration on these different aspects and their net effect on flavour are discussed.