Storage Stability of Nonpackaged Irradiated Indian Mackerel (Rastrelliger kanagurfa) in Ice

The storage stability of eviscerated Indian mackerel (Rastrelliger kanagurta) irradiated at a dose of 1.5 kGy and held under melting ice was examined. Packaging in polyethylene pouches prior to irradiation gave a shelf-life of 25 days, while, nonpackaged, irradiated fish remained in acceptable condition up to 20 days. The nonpackaged irradiated fish has less irradiation odor and better appearance as compared with packaged irradiated fish during the course of ice storage. Uni-radiated and nonpackaged mackerel kept in ice were acceptable only for 14 days. The results suggest that pre-irradiation packaging was not essential for commercially adequate extension in shelf-life of the iced fish.     

Microorganisms on Commercially Processed Alaskan Finfish

Whole and processed Alaskan fish were examined for aerobic plate counts, total coliforms, and Escherichia coli. Washing whole salmon and halibut reduced skin microbial counts from 10³/cm² to 10²/cm². Whole and dressed fish had coliform counts less than 13/cm² and E. coli counts less than 0.3/cm². Alaska pollock and Pacific cod fillets had microbial counts between 10³/g and 10⁶/g, coliform counts less than 70/g, and E. coli counts less than 4/g. Whole fish contained microbial flora predominated by Moraxella species whereas dressed fish and fillets had microbial flora consisting of Arthrobacter/Corynebacterium, Flavobacterium, and Pseudomonas species. Microorganisms on conveyor belts and other contact surfaces may have contributed contaminants to fillets.     

Effects of storage time and chemical preservatives on the total volatile basic nitrogen content in chilean mackerel (Trachurus murphy) prior to fish meal production

Total volatile basic nitrogen (TVB-N) as a measure of protein degradation and total microbial counts or stored raw mackerel (Trachurus murphy), which had been treated with chemical preservatives, were compared with the TVB-N and microbial counts of untreated fish. In unpreserved fish, decomposition of fish protein was rapid. Treatment of mackerel with acetic (1000-5000 μg kg^?1), which was the most effective of the parameters studied, approximately halved the rate of increase in TVB-N compared with the untreated samples. Changes in the total microbial counts presented a similar trend.     

Changes in acid and alkaline phosphatase activities during the spoilage of raw muscle from horse mackerel Trachurus japonicus and gurnard Lepidotriga microptera

The aim of this work was to provide information on the role of acid phosphatase (Acp) and alkaline phosphatase (Alp) activities as spoilage indicators of raw fish. Horse mackerel Trachurus japonicus, a red-flesh fish, and gurnard Lepidotriga microptera, a white-flesh bottom fish, were stored at 4 °C. The aerobic bacteria count (APC) of horse mackerel skin increased from 10³ to 10⁷ CFU/cm² in seven days, the Alp activity increased about from 10 to 150 nmol p-nitrophenol/min/g tissue with increase of volatile basic nitrogen (VBN), an index of fish spoilage. The APC of gurnard skin also reached 10⁷ CFU/cm² after 8 days’ storage. The Alp activity was twice that of the Acp activity in the fresh gurnard and the activity decreased slightly during the initial 4 days and increased from four days’ storage.     

Incorporation of bacteriocin in plastic retains activity and inhibits surface growth of bacteria on meat

The bacteriocin, nisin, was incorporated into a polyethylene based plastic film and retained activity against the indicator bacteria Lactobacillus helveticus and Brochothrix thermosphacta . Beef carcass surface tissue sections (BCT) topically inoculated with the psychrotrophic spoilage bacterium B. thermosphacta were vacuum-packaged both with and without wrapping with the nisin impregnated plastic and held at 4° C. An initial reduction of 2 log₁₀cycles of B. thermosphacta was observed with nisin-impregnated wrapped BCT within the first 2 days of storage. After 20 days of refrigerated storage, B. thermosphacta populations from nisin impregnated plastic wrapped samples were significantly less than (P<0·05) control vacuum-packaged samples; log₁₀5·8 vs 7·2 cfu cm⁻²respectively. Temperature abuse was simulated by shifting inoculated packs from 4° C (after 2 days) to 12° C. Again, by 20 days, the B. thermosphacta populations of treated samples wrapped with nisin impregnated plastic were significantly less than (P<0·05) control vacuum-packaged samples; log₁₀3·6 vs 6·3 cfu cm⁻²respectively. This work highlights the potential for incorporating antimicrobial peptides with a wider and different range of inhibitory activity directly into plastics of different properties for use in controlling food spoilage as well as preservation to enhance product microbial safety.     

Storage of New Zealand Jack Mackerel (Trachurus novaezelandiae) In Ice: Chemical, Microbiological and Sensory Assessment

Physical, sensory, microbiological and chemical analyses were carried out on jack mackerel during 23 days of storage in ice. Sensory results indicate that jack mackerel used in this trial had a shelf-life of 7 days. Aerobic plate counts never exceeded 10⁶/g flesh during the first 11 days. The K value reached 20% after 7 days. Trimethylamine, total volatile base, pH and thiobarbituric acid analyses were not good indicators of changes in quality during the shelf-life. Proximate analyses were carried out on representative samples of the fish.     

Comparison of Shelf Life and Quality of Mullet Stored at Zero and Subzero Temperature

The shelf life and quality of mullet (Mugil spp.) caught off the Southeast Atlantic coast were evaluated during storage at subzero temperature (-2°C) either unpackaged or vacuum packed in iolon film. Subzero temperature was maintained by storing fish in either 2% NaCl- or 7% propylene glycol-ice. Shelf life of fish stored in -2°C ice was 10 days, compared to 7 days for the fish stored in 0°C ice. Extension of shelf life was attributed to delayed microbial growth and slow biochemical changes. Structural changes due to ice crystals at subzero temperature storage appeared to be minor compared to those which occurred during freezing at -20°C as revealed by microscopic examination. The minor structural changes along with insignificant biochemical changes resulted in products having acceptable eating quality for 10 days.     

High pressure processing on microbial inactivation,quality parameters and nutritional quality indices of mackerel fillets

The objective of this study was to investigate the effect of high pressure processing (HPP) (100, 300 or 500 MPa for 2 or 5 min) on microbial inactivation, quality parameters and nutritional quality indices of mackerel fillets. A significant reduction in TVC and H₂S-producing bacteria was detected at 300 MPa for 5 min and 500 MPa for 2 or 5 min. Lightness (L*) increased and redness (a*) decreased at the highest treatment intensities. Hardness, chewiness and springiness increased with the most intense treatments but neither cohesiveness nor TBARS values were affected by pressurization. HPP significantly decreased levels of EPA, PUFAs, HUFAs, DHA, CLAs and increased MUFAs and SFAs. TI significantly increased at the highest pressurization intensities and AI was affected when HPP was held for 5 min. However, the ratio PUFA/SFA above 0.45 in pressurized mackerel fillets indicated that HPP did not compromise the nutritional value of this pelagic fish.Industrial relevanceThe potential of HPP to inhibit spoilage and increase the shelf-life of mackerel fillets, while maintaining its quality and healthy attributes, could help the fish processing industry to ensure better quality raw material for further processing, thereby enabling the development of new, value-added products with extended shelf- life. The reduction in the processing time with the subsequent saving of energy compared to conventional thermal methods makes HPP a relatively energy efficient and suitable preservation treatment for the fish industry.     

The effect of temperature on microbial growth in apple cubes packed in film and preserved by use of orange juice

Red delicious apple cubes were packed in fresh orange juice containing chemical preservatives (citric and ascorbic acid, potassium sorbate) and covered with plastic films of different gas permeabilities (polyethylene and EVA‐SARAN‐EVA) before storage at 4, 10 and 20 °C. The concentration of potassium sorbate in the product was optimized with respect to colour and microbial growth. Yeast and mould growth was modelled by Gompertz and linear equations to derive parameters such as lag phase, maximum microbial population and specific microbial growth or rates of decline. Activation energies for the specific growth rates were estimated from Arrhenius‐type equations and the time required to reach microbial counts of 10^6±0.2 CFU g^?1 was determined in all cases. At 4 °C, these values were longer than 25 days in all systems tested. The use of a low gas permeability film and an adequate potassium sorbate concentration extended storage life at higher temperatures.     

Microbial Safety and Shelf Life of UV‐C Treated Freshly Squeezed White Grape Juice

The effects of UV‐C irradiation on the inactivation of Escherichia coli K‐12 (ATCC 25253), a surrogate of E. coli O157:H7, and on the shelf life of freshly squeezed turbid white grape juice (FSWGJ) were investigated. FSWGJ samples were processed at 0.90 mL/s for 32 min by circulating 8 times in an annular flow UV system. The UV exposure time was 244 s per cycle. The population of E. coli K‐12 was reduced by 5.34 log cycles after exposure to a total UV dosage of 9.92 J/cm² (1.24 J/cm² per cycle) at 0.90 mL/s flow rate. The microbial shelf life of UV‐C treated FSWGJ was extended up to 14 d at 4 °C. UV exposure was not found to alter pH, total soluble solid, and titratable acidity of juice. There was a significant effect (P < 0.05) on turbidity, absorbance coefficient, color, and ascorbic acid content. Furthermore, all physicochemical properties were altered during refrigerated storage. The microbial shelf life of FSWGJ was doubled after UV‐C treatment, whereas the quality of juice was adversely affected similarly observed in the control samples.     

Microbial Activity Inhibition in Chilled Mackerel (Scomber Scombrus) by Employment of an Organic Acid‐Icing System

Abstract: The present study concerns Atlantic mackerel (Scomber scombrus) traded as a chilled product. The study was aimed to investigate the effect of including a mixture of organic acids (citric, ascorbic, and lactic) in the icing medium employed during the fish chilled storage. To this end and according to preliminary trials results, an aqueous solution including 0.050% (w/v) of each acid was employed as icing medium; its effect on the microbial activity development in mackerel muscle was monitored for up to 13 d of chilled storage and compared to a counterpart‐fish batch kept under traditional water ice considered as control. Results indicated a lower bacterial growth in mackerel muscle subjected to storage in the organic acid‐icing system by comparison with control fish. Thus, statistically‐significant (P < 0.05) differences between both batches for all 6 microbial groups investigated (aerobes, anaerobes, psychrotrophes, Enterobacteriaceae, lipolytics, and proteolytics) and for 2 chemical indices related to microbial activity development (total volatile bases and trimethylamine) were obtained. The surface wash caused by the melting of the ice during storage and the subsequent antimicrobial effect of such acids on skin microflora of the fish can be invoked as the main reasons for the limited bacterial growth found in the corresponding mackerel muscle. Practical Application: Among natural antioxidants, citric, ascorbic, and lactic acids are low molecular weight organic compounds that represent a relevant choice because of their easy availability, low commercial cost, and wide range of permitted concentrations for their use in foods. Present results obtained by their inclusion in a novel icing system have led to a lower microbial development in chilled mackerel when compared to its counterpart fish kept under traditional icing conditions. Such a finding indicated that inclusion of this acid mixture in the icing medium can lead to a marked quality and safety enhancement as well as to profitable commercial value increases.     

Quality assessment of gutted wild sea bass (Dicentrarchus Labrax) stored in ice, cling film and aluminium foil

The effects of aluminium foil and cling film on microbiological, chemical and sensory changes in wild sea bass (Dicentrarchus labrax) stored at chill temperature (4 °C) were studied. A quality assessment of wild sea bass stored in ice, in boxes without ice, wrapped in aluminium foil (WAF) and wrapped in cling film (WCF) at 4 °C was performed by monitoring sensory quality, nucleotide breakdown products, total volatile base nitrogen (TVB-N), and total viable counts (TVCs). The observed organoleptic shelf-life of sea bass was found to be 16 days in ice, 4 days in boxes without ice, 8 days in aluminium foil and 8 days in cling film. Demerit points did not differ significantly (P>0.05) between WCF fish and WAF fish. The nucleotide degradation pattern was found to be similar for all storage conditions except for inosine and hypoxanthine contents, which decreased after 12 days of storage for WAF and WCF. The content of TVB-N for all storage conditions showed similar tendencies until 12 days storage but reached the highest level (41.6 mg TVB-N 100 g^–1 flesh) for fish stored in WAF and WCF. No significant differences (P>0.05) were found in TVB-N concentrations within the treatments during the early stages of the storage period. Bacteria grew most quickly in the sea bass kept in boxes without ice, followed by those kept WAF, WCF and in ice. Significant differences (P<0.05) in TVC were observed amongst the treatments, especially between fish stored in boxes without ice and fish stored in ice     

Potassium Sorbate Inhibition of Microorganisms Growing on Refrigerated Packaged Beef

The influence of potassium sorbate concentration (27–1325 ppm of sorbic acid) on the growth of natural flora in raw beef samples wrapped in plastic films of different oxygen permeability was studied at 0° and 4°C. Changes in aerobic plate counts, Pseudomonas spp., Brochothrix thermosphacta, Lactobacillus spp., Enterobacteriaceae and yeasts were monitored. Sorbate treatment effect on percentage increment of lag phase and reduction of growth rate during exponential phase for the different microorganisms were analyzed and antimicrobial action was evaluated by the Inhibition Index. A significant increase in the time to reach aerobic counts of 10^6.5 CFU/cm² was observed at low storage temperatures and pH values in vacuum packaged treated samples.     

Hyperbaric cold storage: Pressure as an effective tool for extending the shelf-life of refrigerated mackerel (Scomber scombrus,L.)

The efficacy of hyperbaric cold storage for preserving lean fish has been recently demonstrated but, to the best of our knowledge, no data exist for fatty fish. To evaluate the effect of hyperbaric cold storage on the shelf-life and quality of fatty fish, we stored Atlantic mackerel fillets at 5 °C, both at atmospheric pressure and at 50 MPa. After 12 days of hyperbaric storage, no microbial growth was observed. Thus, most counts were similar or slightly lower than those of control samples at day 0, while H₂S-producing organisms and sulphite-reducing bacteria reduced under the detection limits. Moreover, no significant lipid degradation was observed. By contrast, increased microbial counts and significant lipid hydrolysis were detected in the samples stored at atmospheric pressure. Moreover, even though the protein profile was significantly altered during hyperbaric storage, most fish-quality indicators (pH, TVB-N, drip loss, water-holding capacity, and firmness after cooking) were better preserved in the mackerel samples stored at 50 MPa. These results clearly prove that hyperbaric cold storage was more efficient than conventional refrigeration for the preservation of Atlantic mackerel fillets.Industrial relevanceLong-term preservation of fatty fish is a challenge for the seafood industry mainly due to lipid degradation that can rapidly reduce fish quality. If effective against lipid degradation, hyperbaric cold storage could be an interesting technology to preserve fish and fish products. The increased cost resulting from hyperbaric storage should be overcome by an extended shelf-life of a high-quality product.     

Incidence of histidine decarboxylating bacteria in fish and market environs

To understand the sources of contamination of fish with histidine decarboxylating bacteria (HDB), the fish market environs including fish carrying baskets, ice, market floor and water used for wetting fish, were studied for HDB counts. Fish such as seerfish (Scomberomorus guttatus) and mackerel (Rastrelliger kanagurta) were also studied for total plate count (TPC), HDB counts and levels of histamine. The results suggest that the HDB are widely distributed in the market environs and market floor and that water could be major sources of contamination of fish. While the samples of seerfish studied had very low levels of histamine, some mackerel samples had levels exceeding 10 mg%.     

The Effect of Ultraviolet Light on Microbial Inactivation and Quality Attributes of Apple Juice

Non-thermal technologies such as UV irradiation can offer advantages for minimal processing of transparent beverages. In this study, reconstituted apple juice was exposed to UV light in a continuous laboratory scale system at energy dosages ranging from 2.66 to 53.10 J/cm² by changing the exposure time. Treated juices were then evaluated for microbial inactivation and selected physical and chemical attributes. Product quality was further assessed by sensory evaluation using a 30-member consumer panel. Microbiological analysis was performed by inoculating apple juice with Escherichia coli K12 and Listeria innocua and microbial numbers were counted pre- and post-processing. UV energy levels did not affect pH, °Brix, or total phenols content, but decreased non-enzymatic browning (p < 0.01) and antioxidant capacity (p < 0.05) compared to unprocessed juice. A colour-lightening effect was noted with increasing energy dose. All UV treatments applied (2.66 J/cm² and above) resulted in a reduction below the detection level (<1 log cfu/ml) for both E. coli and L. innocua in apple juice. Sensory evaluation showed that samples treated with energy dosages up to 10.62 J/cm² were comparable to the control in terms of acceptability, though higher dosages produced adverse effects in terms of flavour and colour. Based on these results, UV treatment with low energy dosages could represent a valid alternative to thermal processing to eliminate pathogenic microorganisms while maintaining quality in reconstituted apple juice.     

Sensory,microbial and chemical effects of a slurry ice system on horse mackerel (Trachurus trachurus)

Slurry ice, a biphasic system consisting of small spherical ice crystals surrounded by seawater, was evaluated in parallel with flake ice for the storage of horse mackerel (Trachurus trachurus). Storage in slurry ice led to a significant enhancement of shelf life (5 days for flake ice to 15 days for slurry ice), better control of pH and lower counts of total aerobes and proteolytic and lipolytic bacteria, these reaching an average difference between batches of 2, 1.43 and 1.98 log units respectively after 8 days of storage. Storage in slurry ice also involved a significantly slower formation of total volatile basic nitrogen and trimethylamine after 8 days of storage. Staphylococcus xylosus and Proteus penneri were identified as the leading proteolytic and lipolytic organisms in horse mackerel muscle. Storage of horse mackerel in slurry ice enhances the shelf life of this medium‐fat fish species through better maintenance of sensory and microbiological quality. Copyright © 2004 Society of Chemical Industry     

Effects of sodium acetate dip treatment and vacuum-packaging on chemical,microbiological, textural and sensory changes of Pearlspot (Etroplus suratensis) during chill storage

The effects of sodium acetate dip treatment, followed by vacuum-packaging, on the shelf life of beheaded, scaled and gutted Pearlspot (Etroplus suratensis) during chill storage were examined. Sodium acetate (2%, w/v) solution was used for the dip treatment. Pouches (size: 15 × 22 cm) made of 12μ-polyester laminated with 300 gauge low-density polyethylene were used for packing fish. After packing, all the packs were iced with flake ice in the ratio (1:1) fish: ice in an insulated box and were kept in a cold room maintained at 0–2 °C. The control and the treated packs were analysed periodically for chemical (pH, TBA, TMA, TVB-N), microbiological (total viable count), textural and sensory characteristics. Changes in Staphylococcus aureus, Enterobacteriacea and Feacal streptococci were determined for fresh fish and for fish samples at the time of sensory rejection. Air packed samples were found to have a shelf life of about 8 days; vacuum-packed samples were found to be acceptable up to 10 days, whereas sodium acetate-treated vacuum packed samples were found to be acceptable up to 15 days. Thus, vacuum-packaging, in combination with sodium acetate, was found to delay the spoilage, thereby significantly extending the shelf life of Pearlspot at refrigeration temperatures.     

Effects of Storage Time and Temperature on the Microflora and Amine-Development in Spanish Mackerel (Scomberomorus maculatus)

Microbial content was characterized and levels of three amines (histamine, cadaverine, and putrescine) were determined in Spanish mackerel (Scomberomorus maculatus) decomposed at PC, WC, and 30°C for varying lengths of time. Correlations were shown (1) between the levels of the histamine, cadaverine, and putrescine and the time and temperature of decomposition, (2) between the ratios of cadaverine/histamine and putrescine/histamine levels and the temperature of decomposition, and (3) between increasing total microbial counts and rising amine levels. A total of 14 bacterial species with histidine decarboxylase activity were isolated from decomposing fish, including three species (Acinetobacter lwoffi, Pseudomonas putrefaciens, and Aeromonas hydrophila) not previously reported to have the potential to produce histamine.