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

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

Behaviour of marine microflora towards antibiotics 1. Sensitivity towards chlortetracycline (CTC)

The sensitivity of 61 cultures of bacteria isolated from fish towards chlortetracycline (CTC) at 5 ppm and 20 ppm levels has been determined on two solid media: sea water agar (SWA) and a distilled water based medium consisting of peptone, beef extract, glucose and NaCI (PBGA). The cultures employed consisted of (i) gram-negative rods of marine origin (Achromobacter, Pseudomonas, Vibrio and Flavobacterium) and (ii) gram positive organisms (Micrococci and Corynebacterium). Depending on the inhibition zone diameter, the order of CTC sensitivity was found to be Pseudomonas<Vibrio<Achromobacter as determined on PBGA at CTC levels of 5 and 20 ppm. The SWA enhanced the development of resistance in majority of the cultures as compared to PBGA. PBG broth containing CTC at less than 10 ppm exerted a bacteriostatic effect only while that containing 10 ppm or more exerted a bactericidal effect on Achromobacter, Pseudomonas and Micrococci cultures. The significance of these results in fish preservation by CTC is discussed

Bacterial flora of fresh and iced Indian mackerel (Rastrelliger kanagurta) and its response to chlortetracycline (CTC) treatment

Quantitative and qualitative studies on the bacterial flora of fresh Indian mackerel (Rastrelliger kanagurta) have been made. The total native flora as well as 5 ppm CTC insensitive flora of the fish showed variations with season. About 90% of the fresh fish flora was sensitive to 5 ppm CTC. The natural flora of the fresh fish consisted of Vibrios, Pseudomonas, Achromobacter, Flavobacterium, Corynebacteria, Micrococci, Bacillus and yeasts. In the CTC insensitive flora, Vibrios predominated followed by yeasts. The selection of bacterial genera during storage of the fish in ice and in 5 ppm CTC incorporated ice has also been investigated. At the time of spoilage, Pseudomonas was found to be the dominant flora of the fish stored in both types of ice

Use of antibiotics in the preservation of prawn

Effect of incorporating chlorotetracycline (CTC) in ice up to 5 ppm level on the keeping quality of prawns has been studied. A shelf life extension by nearly six days is obtained for the CTC-iced sample over the control. The headless prawns absorbed greater amounts of CTC than whole prawns during storage in CTC-ice. Traces of the antibiotic are found in the muscle of the CTC-iced prawns even after cooking for one hour. The cause of destruction of CTC when used for prawn preservation is discussed

Experimental preservation of sardines (Sardinella longiceps), using Chlortetracycline

Effects of dips in 10 and 50 ppm Chlortetracycline solution on the storage-life of sardines in ice have been studied. 5 ppm-CTC-ice in conjunction with dip in 10 ppm CTC-solution has also been tried. CTC-treatment considerably reduced bacterial number and gave a better appearance to the fish. The high fat content in sardines resulted in rapid development of rancidity. CTC has been found to have no control on the development of rancidity. Hence, CTC treatment of sardines is found to be of limited advantage in extending the storage-life of the fish in ice

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 iced storage of cultured rohu (Labeo rohita)

The biochemical, bacteriological and organoleptic changes in cultured rohu (Labeo rohita) during iced storage have been studied. Non-protein nitrogen decreased and water soluble nitrogen remained almost same during storage in ice. Initially, when the fish was in pre-rigor and rigor conditions, the extractability of protein was low (45 to 50%) which increased after the resolution of the rigor and the decrease in extractability towards the end of storage was insignificant. The total volatile base nitrogen remained steady up to 7 days in ice and showed slight decrease on further storage. During iced storage the bacterial count increased from 10^3/g to 10^5/g by the 11th day of storage. Nearly 80-90% of the total bacterial population in fresh fish was constituted by mesophiles which decreased gradually (decreased to 1% by 13th day of iced storage). Organoleptically the fish was acceptable up to 15 days in ice

Delayed freezing on the quality and shelf-life of Kalawa (Epinephelus spp.)

Kalawa (Epinephelus spp.) caught on board FORV Sagar Sampada was frozen in the absolutely fresh condition as well as after keeping for 5 and 10h at ambient temperature. Evaluation of changes in the quality of these samples during storage at -20°C indicated appreciable difference between the fresh frozen and delayed frozen fish during the initial stages of storage. Fresh frozen and 5h delayed froze fish samples had a shelf-life of more than 62 weeks, whereas the 10h delayed frozen fish had a shelf-life of about 48 weeks