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1.
The effect of two slaughter methods (immersion in ice-water slurry and electrical stunning followed by ice slurry asphyxiation) on chemical and microbiological parameters of grass carp (Ctenopharyngodon idella) stored in ice for 20 days was evaluated. No differences in total volatile basic nitrogen (TVB-N), pH, carbohydrate or protein content of mucus were observed between the slaughter methods. Ice-slaughtered fish had lower bacteria counts at the beginning of storage, but higher counts than fish slaughtered by electricity at the end of storage (p < 0.05). However, no significant differences in the shelf life were observed between the slaughter methods evaluated (limit of acceptability – counts > 3 × 106 CFU g−1 – attained after 13–16 days). Results indicated that the chemical parameters evaluated have a limited applicability to assess the shelf life of grass carp stored in ice, since pH limit (6.8) was exceeded after 4 days, while TVB-N limit (30 mg%) was not attained after 20 days of storage.  相似文献   

2.
The use of ozonised slurry ice was investigated as a new refrigeration system for the storage of farmed turbot (Psetta maxima). With this purpose in mind, an ozone generator device was coupled to a slurry ice system working subzero at −1.5 °C. The ozone concentration was adjusted to a redox potential of 700 mV, and the slurry ice biphasic mixture was prepared at a 40% ice/60% water ratio and 3.3% salinity. Certain biochemical parameters indicative of fish freshness, such as the rate of nucleotide degradation or TMA-N formation, were not significantly affected by the presence of ozone in the slurry ice mixture. However, storage in ozonised slurry ice significantly slowed down the mechanisms responsible for lipid hydrolysis and lipid oxidation in farmed turbot. Storage in ozonised slurry ice also led to significantly (p < 0.05) lower counts of both total aerobes and psychrotrophic bacteria in both turbot muscle and skin, as compared with the control batch stored without ozone. Sensory analyses confirmed an extended shelf life of turbot specimens stored in ozonised slurry ice; these maintaining “A” sensory quality up to day 14, while the counterpart batch stored in slurry ice kept this quality only up to day 7. The combination of ozone and slurry ice may be recommended for the chilling and storage of farmed turbot with a view to extending its shelf-life.  相似文献   

3.
Slurry ice, a biphasic system consisting of small particles of spherical ice immersed in seawater at subzero temperature, was evaluated as a new chilled method for whole sea bream (Sparus aurata) and sea bass (Dicentrarchus labrax). Two types of different chilling methods were used for two species in this study; slurry ice-treated sea bream (Group A), slurry ice-treated sea bass (Group B), flake-ice treated sea bream (Group C) and flake ice-treated sea bass (Group D). The effects of this system on the quality and shelf life of these two species were evaluated. Mesophilic counts for sea bass exceeded 7 log cfu/g, which is considered the maximum level for acceptability for freshwater and marine fish after 13 days for Groups C, D and 15 days for Groups A, B. At day 13, TVB-N values of Groups C, D reached the legal limits (35 mg/100 g set for TVB-N) for consumption. According to the results of sensory analyses, up to day 13, all the Groups were determined as ‘acceptable’ but, on day 15, the Groups A, B, C, D were no longer acceptable. Using slurry ice pretreatment for 2 h before the storage period presumably caused the deleterious effect on appearance as well as salt and water uptake. According to the results of chemical and microbiological analyses, use of slurry ice pretreatment for 2 h extended the shelf life of sea bream and sea bass stored at 4 °C for only two days longer than did use of flake ice.  相似文献   

4.
The slurry ice technology has shown profitable advantages when employed instead of traditional flake ice for the manufacture of chilled aquatic species. The present work is aimed at evaluating the effect of slurry ice as a preliminary treatment prior to frozen storage. For it, specimens of a small pelagic fatty fish species (sardine; Sardina pilchardus) were stored in slurry ice for 2, 5 and 9 days, then subjected to freezing (-80 °C; 24 h) and finally kept frozen (−20 °C) during 1, 2 and 4 months. At such times, rancidity development in frozen sardine was measured by sensory (odour, skin, colour and flesh appearance) and biochemical (lipid hydrolysis and oxidation) analyses and compared to a control batch previously chilled in flake ice. Sensory analysis indicated an extended shelf-life time for frozen sardine that was preliminary stored under slurry ice for 2, 5 or 9 days, as compared to their counterparts subjected to flake icing. Sensory results were corroborated (P<0.05) by biochemical lipid oxidation indices (thiobarbituric acid reactive substances and the fluorescence formation). The present work opens the way to the use of slurry ice instead of flake ice as preliminary treatment of fish material prior to the frozen storage.  相似文献   

5.
A relevant farmed fish species (coho salmon; Oncorhynchus kisutch) was studied as a raw material for the canning process. The effects of preliminary chilling storage and thermal treatment (cooking and sterilisation) on the chemical constituents (lipids and non-protein nitrogen compounds) of the canned fish were analysed. An increasing previous chilling time led to an important autolysis (K value) development, and to an increasing formation of free fatty acids, and interaction compounds (fluorescence and browning assessments) (p < 0.05) in the canned product. The thermal treatment led to the formation of volatile amines (total and trimethylamine), free fatty acids, secondary lipid oxidation compounds (anisidine and thiobarbituric acid values) and interaction compounds in canned fish. Interaction compound assessment was found the most useful tool to study the lipid oxidation and non-enzymatic browning developments, while the K value showed to be an interesting index for assessing the freshness stage of the raw material employed.  相似文献   

6.
Slurry ice is a biphasic system that has recently shown a number of advantages when employed as a chilling medium for fish species. Its use for a crustacean species of high commercial value, Norway lobster (Nephrops norvegicus), was evaluated in parallel with traditional flake icing. Quality parameters related to microbial spoilage and biochemical breakdown (aerobe and psychrotroph counts, pH, K value, total volatile amines, trimethylamine, free fatty acids and non‐enzymatic browning reactions) were assessed and compared with sensory (carapace, eyes, gills, odour and flesh) acceptability. Storage in slurry ice produced a significant (P < 0.05) inhibitory effect on both microbial growth (as determined by aerobes, psychrotrophs and volatile amines) and autolysis breakdown (as determined by K values and the release of free fatty acids) in comparison with the flake ice batch. In contrast, an enhancement effect of slurry ice on carapace browning was observed as a result of enzymatic browning development. Slurry ice batch also showed a more intense non‐enzymatic browning reaction in the lipid extract of the edible flesh. With a view to limiting both browning effects, the incorporation of an anti‐melanosis agent in the liquid phase of the slurry ice system is envisaged. Copyright © 2006 Society of Chemical Industry  相似文献   

7.
Rested Atlantic salmon was superchilled in seawater slurry (−1.93 ± 0.27 °C). The chilling efficiencies of slurry and crushed ice were compared. The feasibility of using slurry to produce subzero core temperatures before packing was also evaluated. Simulated transport to market, with or without ice after initial superchilling (1 day), was also studied. Fish quality (Quality Index, fillet colour, pH, water content, water-holding capacity, hardness and bacterial loads) was evaluated at arrival to ‘market’ and after keeping the fish ‘in the market’ for 1 week. The results were compared with continuous ice (control) or slurry storage. In terms of quality, pre-chilling in slurry and continuous storage in slurry were evidently not advantageous over traditional ice storage, as evaluated after 4 days. After 11 days, both advantages and disadvantages of continuous superchilling were observed. Notably, subsequent ice storage of superchilled fish resulted in increased bacterial load and inferior fillet hardness.  相似文献   

8.
V.H Escalona 《LWT》2004,37(1):115-121
The effects of modified atmosphere packaging (MAP) to inhibit browning of the butt end cut zone of fennel bulbs stored during 14 days at 0°C followed by complementary air storage during 3 days at 15°C were studied. Selected bulbs were placed in 35 μm oriented polypropylene bags or in plastic baskets heat-sealed with nonperforated or perforated (control) polypropylene film. Changes in respiratory rate, ethylene emission, colour of both external leaves and butt end cut, as well as chemical and sensory attributes and browning development were monitored. A low to moderate nonclimacteric respiratory behaviour at 0°C with a respiration rate of 8-9 mg CO2 kg−1 h−1 and an ethylene emission of 0.2-0.5 μl C2H4 kg−1 h−1 were found. Development of fungal attacks, chilling injury, decay and browning of external leaves were not detected for any treatment. All the MAP inhibited browning development of the butt end cut when evaluated after cold storage. However only the atmosphere of 6-7 kPa O2 and 10-12 kPa CO2 delayed that process at the end of complementary shelf life.  相似文献   

9.
The quality and physiological changes were determined in peach (Prunus persica L. cv. Jiubao) fruits in low temperature storage with or without methyl jasmonate (MeJA) treatment. Peach fruits stored for 3 weeks at 5 °C and following 3 d shelf life intervals at 20 °C appeared chilling injury (CI) symptom, expressed as flesh browning. MeJA treatment decreased the CI index, which was possibly attributed to higher activity of peroxidase and lower content of phenolic compounds than that without MeJA treatment. Moreover, MeJA treatment not only enhanced the rate of SSC/TA in peach fruits by mainly restraining the decrease of the SSC in peach, but also affected the degradation of cell wall, perhaps by regulation of cell wall modifying enzymes and the calcium content in cell wall of flesh. The results suggested that MeJA treatment was beneficial for maintaining quality owing to reducing chilling injury of peach fruits under low temperature stress.  相似文献   

10.
Once a nuisance by-catch, today the Norway lobster (Nephrops norvegicus) is a valuable UK fisheries commodity. Unfortunately, the species is very susceptible to quality deterioration post harvest as it quickly develops black spots and also spoils rapidly due to bacterial growth. Treatment with chemicals can stop the blackening and carefully monitored cold storage can result in a sensory shelf life of up to 6.5 days. The high susceptibility to spoilage greatly restricts the extent to which N. norvegicus can be distributed to retailers and displayed for sale. The application of modified atmosphere (MA) could be extremely beneficial, allowing the chilled product to stay fresh for a long period of time, thus ensuring higher sales. In the present study, we identified a gas mix for the MA packaging (MAP) of whole N. norvegicus lobster into 200 g retail packs. Our results show that a shelf life extension to 13 days can be achieved when retail packs are stored in MAP at 1 °C. Effectiveness of the MAP was evaluated by using a newly developed QIM for MA-packaged whole N. norvegicus and also by analyzing bacterial plate counts. Changes in the microflora and effects of different storage temperatures on the quality of the MA packs are also presented. The main specific spoilage organism (SSO) of modified atmosphere packaged Norway lobster is Photobacterium phosphoreum.  相似文献   

11.
The use of a combined ozonised-slurry ice system was investigated as a new refrigeration system for the on-board storage of megrim (Lepidorhombus whiffiagonis), a fish species that is usually stored aboard fishing vessels for 1 to 2 weeks. The time elapsed between the catch and unloading at the harbour affects its quality and commercial value directly. Microbiological, chemical and sensory analyses were carried out in megrim after 2 weeks of on-board storage in ozonised slurry ice, slurry ice or flake ice, and for an additional period of 6 days. Sensory analyses revealed that megrim specimens stored in ozonised slurry ice (oSI600 batch) maintained A quality even after 20 days of storage, while counterpart batches stored in flake ice showed B quality at unloading, after 14 days of on-board storage. Storage in ozonised slurry ice (oSI600 batch) also led to significantly (p<0.05) lower counts of aerobic mesophiles, psychrotrophic bacteria, Enterobacteriaceae and proteolytic microorganisms in megrim muscle as compared with flake ice. Biochemical analyses revealed that the use of ozonised-slurry ice or slurry ice alone slowed down the formation of total volatile base-nitrogen (TVB-N) and trimethylamine-nitrogen (TMA-N) in comparison with storage in flake ice, also allowing a better control of pH. Lipid hydrolysis and oxidation events also occurred at a lower rate in the ozonised-slurry ice and slurry ice batches than in the flake ice batch. The present study demonstrates that the combination of slurry ice and ozone for the on-board storage of megrim is advisable, thus improving the quality and extending the shelf life of this fish species.  相似文献   

12.
Broccoli (Brassica oleracea var. italica) is a vegetable that requires the application of postharvest techniques to extend its marketability. Controlled atmosphere and 1-MCP treatments are most used to extend the shelf life of broccoli and reduce post-harvest deterioration. The aim of this study was to evaluate the visual, physicochemical and functional changes of broccoli head samples stored at 1–2 °C and 85–90% relative humidity (RH) in air (Control samples), under controlled atmospheres (10% O2 and 5% CO2) (CA samples) and treated with 1-MCP (0.6 μL/L). After storage all samples were maintained at 20 °C for 2 and 4 days, in order to assess their shelf life. The most suitable postharvest treatment to extend broccoli quality during storage and shelf life, in terms of maintaining the visual quality and reducing loss of health-promoting compounds, was achieved by storage under controlled atmosphere conditions. The use of 1-MCP reduced the loss of green colour and chlorophyll pigments, but only during cold storage not during shelf life at 20 °C.  相似文献   

13.
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  相似文献   

14.
The quality assessment of wild European eel (Anguilla anguilla) stored in ice and in boxes without ice (3 ± 1 °C) was investigated by the sensory analysis, levels of nucleotide breakdown products and biogenic amines for up to 19 days. Sensory analysis was assessed using the Tasmanian Food Research Unit Scheme. K and related values (Ki, G, P, H and Fr) were used as freshness indicators. Linear regressions (r2) obtained from K, Ki, G, P, H and Fr were 0.95, 0.96, 0.83, 0.96, 0.99 and 0.96, respectively, for eel stored in ice whereas, for eel kept in boxes without ice, the values were 0.86, 0.86, 0.96, 0.91, 0.98 and 0.86, respectively. When eel stored in ice and in boxes without ice were considered at the limit of acceptability by assessors at ∼12–14 days and ∼5–7 days, respectively, the average K, Ki and P values were ∼70–85%, H values were ∼60% and Fr values were ∼10% for both storage conditions. The level of histamine exceeded the legal limit (5 mg/100 g fish) in eel stored without ice after 6–7 days and, in ice, after 13–14 days of storage, at which time eels were rejected by the sensory panel. The concentrations of biogenic amines were higher in eel stored in boxes without ice than in eel kept in ice. The levels of histamine in the muscle of eel kept in boxes without ice and in ice increased to the maximum levels of 17.9 mg/100 g on day 12 and 12.6 mg/100 g on day 19, respectively.  相似文献   

15.
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.  相似文献   

16.
Jinhua Du  Yucheng Fu  Niya Wang 《LWT》2009,42(2):654-659
Effect of aqueous chlorine dioxide (ClO2) treatment on browning of fresh-cut lotus root (FLR) was investigated to explore the feasibility to apply ClO2 for browning inhibition of fresh-cut products. Cut lotus roots were treated in ClO2 solutions at different concentrations (10, 50 and 100 mg/l) for different time (5, 10 and 15 min), followed by chilled storage for 8-10 days at 4 °C. Color parameters (L, a and b), polyphenol oxidase (PPO) activity and overall visual quality (OVQ) were measured at one-day interval during storage. Results showed that higher ClO2 concentration and longer treatment time can provide better inhibitory effects on the browning of FLR. ClO2 concentration, treatment time and storage time were three significant factors (P < 0.05) and some significant interactions were observed. PPO activities were largely inhibited by 100 mg/l ClO2 treatment for 10 min. The 100 mg/l ClO2 treatment maintained high OVQ scores during 10-day storage; while 50 mg/l ClO2 treatment was acceptable for maintaining OVQ during 4-day storage. ClO2 treatment was demonstrated to be a promising alternative approach to control browning and improve OVQ of FLR.  相似文献   

17.
Effects of rapid chilling of carcasses (at − 31 °C in the first 3 h of chilling, and then at 2–4 °C) and earlier deboning (8 h post-mortem), compared to rapid (till 24 h post-mortem) and conventional chilling (at 2–4 °C, till 24 h post-mortem), on quality characteristics of pork M. semimebranosus and cooked ham were investigated. Quality measurements included pH value, colour (CIEL*a*b* values) and total aerobic count of M. semimebranosus, as well as sensory (colour, juiciness, texture, and flavour), physical (pH value, colour – CIEL*a*b* values and texture – Warner–Bratzler shear and penetration forces) and chemical (protein, total fat, and moisture content) characteristics of cooked ham. The cooked ham was manufactured from pieces of M. semimebranosus with ultimate lightness (CIEL* value) lower than 50. Rapid chilling and earlier deboning significantly increased quantity of M. semimebranosus desirable for cooked ham manufacturing. Earlier start of pork fabrication did not affect important quality characteristics of cooked ham.  相似文献   

18.
This study identified and validated high hydrostatic pressure processing (HPP) for achieving greater than 3.52-log reductions of Vibrio parahaemolyticus in the Pacific oysters (Crassostrea gigas) and determined shelf life of processed oysters stored at 5 °C or in ice. Raw Pacific oysters were inoculated with a clinical strain of V. parahaemolyticus 10293 (O1:K56) to levels of 104-5 cells per gram and processed at 293 MPa (43 K PSI) for 90, 120, 150, 180 and 210 s. Populations of V. parahaemolyticus in oysters after processes were analyzed with the 5-tube most probable number (MPN) method. Negative results obtained by the MPN method were confirmed with a multiplex PCR detecting genes encoding thermolabile hemolysin (tl), thermostable direct hemolysin (tdh) and TDH-related hemolysin (trh). A HPP of 293 MPa for 120 s at groundwater temperature (8 ± 1 °C) was identified capable of achieving greater than 3.52-log reductions of V. parahaemolyticus in Pacific oysters. Oysters processed at 293 MPa for 120 s had a shelf life of 6-8 days when stored at 5 °C or 16-18 days when stored in ice. This HPP can be adopted by the shellfish industry as a post harvest process to eliminate V. parahaemolyticus in raw oysters.  相似文献   

19.
The kinetic behavior of Listeria monocytogenes in 2 commercial ice cream products (A and B) that were inoculated and stored under static chilling (4 to 16°C), static freezing (−5 to −33°C), dynamic chilling, and dynamic chilling-freezing conditions was studied, simulating conditions of the aging process and of normal or abuse conditions during distribution and storage. The ice cream products A and B had different compositions but similar pH (6.50 and 6.67, respectively) and water activity (0.957 and 0.965, respectively) values. For both chilling and freezing conditions, the kinetic behavior of the pathogen was similar in the 2 products, indicating that the pH and water activity, together with temperature, were the main factors controlling growth. Under chilling conditions, L. monocytogenes grew well at all temperatures tested. Under freezing conditions, no significant changes in the population of the pathogen were observed throughout a 90-d storage period for either of the inoculum levels tested (103 and 106 cfu/g). Growth data from chilled storage conditions were fitted to a mathematical model, and the calculated maximum specific growth rate was modeled as a function of temperature by using a square root model. The model was further validated under dynamic chilling and dynamic chilling-freezing conditions by using 4 different storage temperature scenarios. Under dynamic chilling conditions, the model accurately predicted the growth of the pathogen in both products, with 99.5% of the predictions lying within the ± 20% relative error zone. The results from the chilling-freezing storage experiments showed that the pathogen was able to initiate growth within a very short time after a temperature upshift from freezing to chilling temperatures. This indicates that the freezing conditions did not cause a severe stress in L. monocytogenes cells capable of leading to a significant “additional” lag phase during the subsequent growth of the pathogen at chilling conditions. As a result, the application of the model at chilling-freezing conditions resulted in satisfactory performance, with 98.3% of the predictions lying within the ± 20% relative error zone. The present study provides useful data for understanding the behavior of L. monocytogenes in ice cream stored under single or combined chilling and freezing conditions. In addition, the study showed that such data can be expressed in quantitative terms via the application of mathematical models, which can be used by the dairy industry as effective tools for predicting the behavior of the pathogen during the manufacture, distribution, and storage of ice cream products.  相似文献   

20.
Freshness of wild turbot (Scophtalmus maximus) stored in ice was assessed by chemical, sensory and microbiological methods. The limit for sensory acceptability of wild turbot stored in ice was ∼12–15 days. The quality of turbot decreased on day 15 (B) and they were no longer acceptable on day 19 (C). The TVB-N level showed fluctuations during storage, indicating that TVB-N could not be a good indicator of turbot quality. The release of FFA increased from an initial value of 6.33 (expressed as % of oleic acid) to a final value of 20.6 during the storage period. The initial PV value was 5.60 meq/kg for turbot stored in ice and it started to increase to 21.6 meq/kg on day 12 and then started to decrease to 13.6 meq/kg at the end of storage period. The level of TMA in wild turbot increased sharply from an initial value of 9.36 mg/kg to a final value of 38.9 mg/kg. Linear regressions (r2) obtained from K, Ki, G, P, H and Fr were 0.92, 0.89, 0.99, 0.89, 0.96 and 0.89, respectively, for the wild turbot stored in ice. Turbot maintained high (E) and good quality (A) during the first 12 days of chilled storage when the average K, Ki and P values were ∼78–85%, and H, Fr and G values were ∼45%, 15% and 149%, respectively. Eight biogenic amines were investigated, namely, histamine, putrescine, cadaverine, spermidine, spermine, tryptamine, tyramine, and 2-phenylethylamine, three amines (histamine, tyramine, and tryptamine) were not detected in any of the fish samples during the storage period. As storage time progressed, putrescine and cadaverine became the dominant amines, reaching 22.7, and 16.9 mg/kg, respectively, at 19 days of storage in ice. Total viable counts of whole gutted turbot increased from the initial value of 3.3 log cfu g−1 (day 0) to 7.87 log cfu g−1 (day 19) over the period of storage. If 106 microorganisms/g are considered to be the TVC limit of acceptability, the shelf life of turbot was approximately ∼13–14 days.  相似文献   

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