Trimethylamine Nitrogen Research Articles

Biochemical and Sensory Acceptability Changes of Fish Cutlet Prepared from Filleting Waste of Reef Cod (E pinephelus chlorostigma ) during Frozen Storage

In the present investigation, fish cutlet was prepared from recovered meat of filleting residue of Epinephelus chlrostigma and their effect on the biochemical and sensory characteristics have been studied during the frozen storage. Biochemical parameters viz., total volatile base nitrogen, trimethylamine nitrogen, peroxide value, free fatty acids and thiobarbituric acid value of prepared fish cutlet were found to increase during the frozen storage (−20C) of 4 months significantly (P < 0.05) and the increment was within the prescribed limits. Sensory analysis reveals a decreasing trend in the attributes like appearance, color, taste, texture, flavor and the overall acceptability was judged to be good at the end of storage study. This study concluded that the meat can be recovered from filleting waste and suitable for the preparation of ready-to-serve fish cutlet without any significant changes in biochemical and sensory evaluation during frozen storage. Practical Applications The present study pave the way for maximum and better utilization of filleting waste of reef cod and also describe the quality changes of prepared fish cutlet during frozen storage. Recovery of meat from fish processing waste and product development add the economic value to the seafood industry and also alleviate the pollution and legal problems associated with the discard of processing waste.

Assessment of caramote prawn(Penaeus kerathurus)proximate value and freshness under ice storage

In this study, the flesh yield and proximate contents of caramote prawn, Penaeus kerathurus, were researched depending on sex and seasons. Furthermore, prawns were divided into two groups for freshness assessments at two different times. The first group of prawn was completely wrapped with the stretch film and aluminium foil and stored at room temperature. The second group was placed in water with ice and stored at 4±1 °C (ice storage). The shelf-life of P. kerathurus was determined. Trimethylamine-nitrogen (TMA-N) and pH were analysed to determine biochemical quality and total mesophilic count (TMC) was measured to determine the microbial quality. In addition, sensory analyses were also carried out. The flesh yield of P. kerathurus was on average 52%. It was found that percentages on average moisture, lipid, protein, and ash contents in P. kerathurus were 76.27%, 1.63%, 16.52%, and 1.98%, respectively, and these values changed depending on the season (P<0.01). Increases in TMA-N, pH, TMC values and chang...

Investigation of quality attributes of ice-stored Pacific white shrimp (Litopenaeus vannamei) as affected by sequential minimal ozone treatment

Ozone treatment is among non-thermal technologies with great promise to the seafood industry. Additionally, the demand for high quality minimally processed food products is increasing worldwide. However, no research endeavors has explored the quality attributes of sequential minimal ozone-treated ice stored shrimp. Therefore, the present investigation was undertaken to study the quality attributes of ice-stored Pacific white shrimp subject to minimal ozone treatment sequentially applied at days 1, 3, 5, 8 and 11. Quality indicators measured include aerobic plate count (APC), titratable acidity (TA), metric chroma, hue difference (ΔH), total colour difference (TCD), trimethylamine-nitrogen (TMA-N), total volatile basic-nitrogen (TVB-N), peroxide value (PV), p-anisidine value (AnV) and total oxidation (totox). The results indicated that the TA, metric chroma, ΔH, TCD, APC, TMA-N, TVB-N, PV, AnV and Totox values changed significantly with storage. Also, statistical differences in correlations and temporal rates of TMA-N and TVB-N as well as PV and AnV of sequential minimal ozone-treated ice-stored shrimp were obtained compared to control (P < 0.05). The noticeable reductions in APC, TMA-N, TVB-N and PV showed sequential minimal ozone treatment to resemble an anti-oxidant and thus, could within the respective limits of acceptability promise the safety of shrimp for consumption.

The effect of vacuum packaging on physicochemical changes in rainbow trout (Oncorhynchus mykiss) during cold storage

The aim of the study was to monitor changes in selected physical (awwater activity, pH values) and chemical (TVBN total volatile basic nitrogen, TMA-N trimethylamine nitrogen, FFA free fatty acids, PV peroxide values, TBA thiobarbituric acid value) properties in the shelf life of rainbow trout (Oncorhynchus mykiss) muscle. A total of 192 trout were examined. Control samples (96 samples) were simply packaged in contact with atmospheric oxygen, while experimental samples (96 samples) were packaged in a commercial vacuum (98%). All the samples were stored at 2 ± 2° C for 11 days. Analyses were performed on storage days 1, 2, 4, 7, 9, and 11. During the experiment, aw values increased in both types of packaging (in air: 0.982; vacuum-packaged: 0.989). At the end of storage, TVBN and TMA concentrations were at 28.88 ± 4.42 and 19.28 ± 3.00 g mg·100-1, respectively, in the muscle of vacuum-packaged trout; and at 30.52 ± 2.91 and 19.94 ± 2.05 mg·100 g-1, respectively, in fish in simple packaging. The FFA content in vacuum-packaged fish initially declined before increasing to 3.67 ± 2.37% of total fat as oleic acid later in the experiment. The pattern of PV changes was inconclusive, and significant changes (P &lt; 0.01) were observed in both types of packaging. On monitoring day 11, TBA values had ​​increased to 7.34 ± 3.10 mg·kg-1 in vacuum-packaged fish and to 26.03 ± 8.00 mg·kg-1 in fish in simple packaging. Free fatty acids are not a good indicator of spoilage because they are converted to hydroperoxides. Vacuum packaging effectively slowed down oxidative changes in rainbow trout muscle. The peroxide content is not a suitable indicator of shelf life as peroxides are decomposed to secondary products. Total volatile basic nitrogen and thiobarbituric acid value can be recommended as suitable indicators of freshness and shelf life.

Biochemical, Physical, Chemical, and Microbiological Assessment of Blue Shrimp (Litopenaeus stylirostris) Stored in Ice

Postmortem changes in blue shrimp (Litopenaeus stylirostris) muscle were studied on the basis of biochemical, chemical, physical, and microbiological changes during an 18 day storage period at 0°C. Adenosine 5′-triphosphate (ATP) content, breakdown products, K-value, pH, trimethylamine nitrogen (TMA-N), total volatile basic nitrogen (TVB-N), water holding capacity (WHC), color, and texture (shear force) changes were examined. Also, total mesophilic and psychrophilic bacterial counts were measured. K-value increased linearly (r2 = 0.98) from an initial value of 1.37 ± 0.59 to 59.42 ± 6.05% at Day 18. Spoilage indicators TVB-N and TMA-N increased from 29.56 ± 1.33 and 0.69 ± 0.25 to 39.04 and 2.04 ± 0.59 mg of N/100 g at Day 18, respectively; meanwhile, the total viable counts of mesophilic and psychrophilic bacteria increased from 3.48 ± 0.44 and 2.61 ± 0.29 log CFU/g to 6.27 ± 0.21 and 7.14 ± 0.39 log CFU/g, respectively, which indicated spoilage at the end of the storage period. The pH, texture, WHC, and color were affected (p < 0.05) during the storage period. Overall, results indicate that blue shrimp muscle quality was maintained for 12 days of storage in ice.

Agar films containing green tea extract and probiotic bacteria for extending fish shelf-life

A bioactive film composed of agar, incorporating green tea extract and probiotic strains (Lactobacillus paracasei L26 and Bifidobacterium lactis B94) was applied on hake fillets in order to evaluate the effect of the films during 15 days of storage. Hake was previously inoculated with Shewanella putrefaciens and Photobacterium phosphoreum (103–104 CFU/g) to simulate a spoilage process. The green tea and/or probiotic film provoked a reduction, particularly of H2S-producing bacteria counts and total viable bacteria throughout the storage period. The probiotic strains added to the film could pass to the fish producing an increment of lactic acid bacterial counts, even in the presence of green tea extract. The effect of the films also caused a decrease in the indexes of fish quality (total volatile basic nitrogen (TVB-N), trimethylamine nitrogen (TMA-N) and pH). The total viable counts, H2S-producing microorganisms and TVB-N were maintained below the limits of acceptability during 15 days for the fillet covered with the green tea + probiotic film, compared to the rest of the samples. Films with green tea and probiotic were able to extend shelf-life of hake at least for a week and increase the beneficial lactic acid bacteria in fish.

Extension of the shelf life of chilled hake (Merluccius merluccius) by a novel icing medium containing natural organic acids

Three combinations of two natural organic acids, citric acid (CA) and lactic acid (LA), in the form of novel flake icing systems were evaluated for the preservation of European hake (Merluccius merluccius), one of the most commercialised gadoid fish species in Europe. The flake icing systems were prepared with fresh water and 0.075%/0.050% (C-75 batch), 0.125%/0.050% (C-125 batch) and 0.175%/0.050% (C-175 batch) CA/LA, respectively. Aerobic mesophiles, psychrotrophs, proteolytic bacteria, anaerobes, Enterobacteriaceae, trimethylamine, lipid hydrolysis, primary, secondary and tertiary lipid oxidation events, and pH levels were evaluated in hake muscle in all batches during 13 d of chilled storage and the results were compared with sensory analyses. Significantly (p < 0.05) lower microbial counts were found in the C-175 batch for all five microbial groups investigated when compared with the control batch, with differences between batches of greater than 2 log CFU/g in the case of aerobes and anaerobes. The presence of organic acids in the icing systems also inhibited (p < 0.05) the increase in trimethylamine-nitrogen (TMA-N) content, with greater inhibition as the CA concentration in the ice increased. An inhibitory effect (p < 0.05) on fluorescent compound formation due to the presence of organic acids in the icing systems, which is indicative of tertiary lipid oxidation, was also observed at advanced storage times. These results correlated well with sensory analysis, which revealed that the shelf lives of the C-125 and C-175 batches were extended. The melting of the ice crystals containing the natural organic acid solutions, especially in the C-175 batch, exerted an antimicrobial washing effect that may explain the better protection of hake quality when stored in the proposed flake icing system.

Deterioration due to delayed icing and its impacts on the nutritional quality of Malabar travally (Carangoides malabaricus)

SummaryEffect of delayed icing of the fish Carangoides malabaricus was assessed using chemical and microbial methods to determine the impacts on the nutritional quality and sensory changes. The shelf life of the fishes iced immediately after harvest had a shelf life of 18 days, whereas the delay of icing for 4, 6, 8 and 10 h shortened the shelf life to 14, 10, 6 and 3 days respectively. The spoilage indicators, such as trimethylamine nitrogen, Total volatile basic nitrogen, free fatty acids, peroxide value, thiobarbituric acid and pH values, significantly increased (P &lt; 0.05) during the storage period of fishes with delayed icing. The total bacterial count also increased during the storage period and due to quality deterioration, the protein and lipid contents were found significantly low (P &lt; 0.05). This study showed that chemical and microbial changes of the sample are well correlated with nutritional and sensory qualities so that immediate icing is important for maintaining the quality and shelf life of C. malabaricus.

Shelf‐Life Extension and Safety Concerns about Haddock (Merlangius euxinus) under High Hydrostatic Pressure

AbstractHaddock (Merlangius euxinus) samples were treated with high hydrostatic pressure at 200, 300 and 400 MPa, at 5, 10 and 15C for 5 and 15 min. Color (L*, a*, b* and ΔE), trimethylamine nitrogen and thiobarbituric acid were monitored. According to the results, 200 MPa, 5C for 5 min and 400 MPa, 15C for 5 min were chosen as treatment combinations for shelf‐life analysis and samples treated at these combinations were stored at 4C for 15 days. Sensory, physical, chemical and microbiological analyses were performed during refrigeration storage. According to the limitations for quality and freshness; samples pressurized at 200 MPa, 5C for 5 min and at 400 MPa, 15C for 5 min were rejected after 13 and 15 days, respectively, whereas unpressurized control samples were rejected within 5 days.Practical ApplicationsHigh hydrostatic pressure (HHP) application is a globally known processing technique that inactivates microorganisms and preserves freshness with minimal quality degradation of foods. Here, we demonstrate the application of HHP providing safe, fresh‐tasting, nutritive, shelf‐stable fish fillets by avoiding undesired changes via thermal treatments and chemical preservatives. HHP could extend the shelf life of haddock at 4C an additional 12 days, preserving its freshness, and could purvey as an alternative commercial fish production technique in addition to traditionally existing methods like freezing, chilling or marinating.

Influence of Heat Penetration on the Quality of Canned Ribbon Fish (Trichiurus lepturus )

Influence of heat penetration on the quality changes of ribbon fish canned in different media, oil and curry using tin-free steel cans, was assessed. The total process time for ribbon fish in oil pack was 47 min, and curry pack was 68 min, with a lethality value of 12.84 and 10.8 min for oil and curry pack, respectively. The biochemical and sensory analysis of the products was done during a storage period of 5 months. Total volatile base nitrogen and tri-methylamine nitrogen contents were found to be slightly higher but within the acceptable limit at the end of 5-month storage, while thiobarbituric acid and free fatty acid content increased slightly in curry and oil pack at the end of the storage period. The sensory quality of the processed products was rated as good by the taste panel, and the products were in acceptable condition even after storage of 5 months at room temperature (28 ± 2C). Practical Applications The present work on the development of ready-to-serve ribbon fish canned products will help in meeting the present demand in the market; if commercialized, it may be a better method of utilization of this presently underutilized fish to fetch higher value to both fishermen and processor besides providing a new and low cost raw material base to canning industry as well as it forms a means of diversification. It was found that tin-free steel cans are suitable for processing fish products, so they can be used as an alternative to tin and aluminum cans because of their capacity to withstand all the conditions of thermal processing.

Effect of High Hydrostatic Pressure Treatment (HHPT) on Quality and Shelf Life of Atlantic Mackerel (Scomber scombrus)

The ability of high hydrostatic pressure treatment (HHPT) to extend the shelf life of Atlantic mackerel (Scomber scombrus) was assessed in this study. For that purpose, fillets were subjected to pressure treatments at 200, 300, 400 MPa at 5, 10, 15 °C for 5 and 15 min. The influence of pressure treatments on the levels of trimethylamine nitrogen (TMA-N) and thiobarbituric acid (TBA) as well as color changes was investigated. The suitable combinations were determined as 200 MPa, 15 °C for 5 min. and 400 MPa, 5 °C for 5 min. In the second stage, the shelf life of samples, which were treated at these conditions, stored at 4 ± 0.5 °C were studied by monitoring pH, color, sensorial features (appearance and odor), TMA-N, TBA, total volatile basic nitrogen, histamine, and total mesophilic aerobic count. The unpressurized mackerel samples were acceptable up to only 7 days compared to 17 and 19 days after 200 and 400 MPa treatments; respectively. The results obtained in this study showed that HHPT in combination with chilled storage can improve the shelf life and quality of fish.

Quality changes of farmed cobia steaks held in cold stores (−18 °C)

SummaryCobia (Rachycentron canadum) steaks held in cold store (−18 °C) were analysed aseptically in triplicates for the sensory, total aerobic bacterial count, proximate composition, pH, thiobarbituric acid‐reactive substance (TBA‐RS), formaldehyde, total volatile base nitrogen (TVB‐N), trimethyl amine‐nitrogen (TMA‐N), salt soluble nitrogen (SSN), nonprotein nitrogen (NPN), sodium dodecyl sulphate‐poly acrylamide gel electrophoresis (SDS‐PAGE) pattern. Steaks were sensorially acceptable up to 5 months of storage and the total bacterial counts did not exceed 6 log CFU counts. There were no significant changes in the pH values. TBA‐RS values increased significantly (P &lt; 0.05) and reached 7.34 mg of malonaldehyde kg−1 fat at the end. Formaldehyde content remained constant upto 4th month and later increased to 2.06 μg g−1 (P &lt; 0.05). TVB‐N and TMA‐N values did not exceed the acceptable limits. NPN contents showed no change, while SSN contents increased to 1.24% after 5 months. SDS‐PAGE pattern indicated no protein denaturation in the fish tissue. Results indicated that TBA‐RS value can only be considered as the valuable indicator in determining the quality of fish steaks held in cold stores.

QUALITATIVE ASSESSMENT IN SALTED RED MULLET (MULLUS SURMULETUS, L. 1758)

In this study, microbiological and chemical properties of red mullet (Mullus surmuletus, L. 1758), treated by dry salting and stored for 120 days at 4 ± 1oC, were investigated. Samples were divided in two lots and put in glass (G) and in glazed crock (C) jars. Microbial load was low at 0 day and during a 120 day period; aerobic mesophilic, psychrophilic and alophilic/alotollerant bacteria counts increased during the first 7 days in both samples; then, a decrease occurred during the whole ripening period; total coliforms and yeast-mould counts were always low. Samples microbial load at 0 day showed a good quality of not processed fishes. pH value at 0 day was 6.65; then it decreased during ripening. Total volatile basic nitrogen and trimethylamine nitrogen values, at 0 day, were low (6,982 mg/100 g; 2,618 mg/100 g, respectively); during ripening the amounts slightly increased in both samples. Overall, a good samples stability during the whole ripening period was considered. Several volatile compounds were identified in all Mullus surmuletus specimens by SPME-GC-MS; in all the samples hexanal, heptanal and (Z)-4-heptanal, typical aroma compounds in salted fish, prevailed. Statistically significant (P< 0,05) differences between G and C and control sample (0 day) during ripening of salted mullet for chemical aspects were observed. The results, altogether, showed that dry salting process is useful to give stability to Mullus surmuletus. The jar material improved the development of typical aroma compounds and it could be proposed for a niche product made for use in a small and specialized, but profitable, market. The glass could be used for industrial production since it provides uniformity for aroma during the maturation.

QUALITATIVE ASSESSMENT IN SALTED RED MULLET (MULLUS SURMULETUS, L. 1758)

In this study, microbiological and chemical properties of red mullet (Mullus surmuletus, L. 1758), treated by dry salting and stored for 120 days at 4 &plusmn; 1&ordm;C, were investigated. Samples were divided in two lots and put in glass (G) and in glazed crock (C) jars. Microbial load was low at 0 day and during a 120 day period; aerobic mesophilic, psychrophilic and alophilic/alotollerant bacteria counts increased during the first 7 days in both samples; then, a decrease occurred during the whole ripening period; total coliforms and yeast-mould counts were always low. Samples microbial load at 0 day showed a good quality of not processed fishes. pH value at 0 day was 6.65; then it decreased during ripening. Total volatile basic nitrogen and trimethylamine nitrogen values, at 0 day, were low (6,982 mg/100 g; 2,618 mg/100 g, respectively); during ripening the amounts slightly increased in both samples. Overall, a good samples stability during the whole ripening period was considered. Several volatile compounds were identified in all Mullus surmuletus specimens by SPME-GC-MS; in all the samples hexanal, heptanal and (Z)-4-heptanal, typical aroma compounds in salted fish, prevailed. Statistically significant (P&lt; 0,05) differences between G and C and control sample (0 day) during ripening of salted mullet for chemical aspects were observed. The results, altogether, showed that dry salting process is useful to give stability to Mullus surmuletus. The jar material improved the development of typical aroma compounds and it could be proposed for a niche product made for use in a small and specialized, but profitable, market. The glass could be used for industrial production since it provides uniformity for aroma during the maturation.

Shelf Life Assessment of Modified Atmosphere Packaged Turbot (Psetta maxima) Fillets: Evaluation of Microbial, Physical and Chemical Quality Parameters

Quality and safety of turbot fillets under modified atmosphere packaging (MAP) were assessed by microbial (total viable counts), physical (drip loss, pH, colour CIE Lab) and chemical parameters (total volatile basic nitrogen (TVBN), trimethylamine nitrogen (TMAN), biogenic amine contents). Three different atmospheres (MAP 1, 10/40/50 % O2/CO2/N2; MAP 2, 10/60/30 % O2/CO2/N2; MAP 3, 10/80/10 % O2/CO2/N2) were tested. Packaged turbot fillets were stored at 2 ± 1 °C and monitored over 30 days, at intervals of 5 days. Fillets from the control group, packaged with air (AIR), were the first to present signs of degradation reaching rejection threshold values for all evaluated parameters. In MAP fillets, total bacterial count was lower than 106 cfu/g for a longer period. After 10 days of storage, MAP and AIR fillets showed significant differences (p < 0.05) on the values of TVBN, TMAN and biogenic amines. MAP fillets presented a higher drip loss, and fillets in AIR became more yellowish (upper b* values) while those in MAP looked whitish for an increased period (upper L* values). All microbial, chemical and physical traits revealed the protective effect of the different MAP studied, especially those with a higher percentage of CO2. MAP application added, at least, 5 days to shelf life of turbot fillets.

Effect of Modified Atmosphere Packaging on Quality and Shelf Life of Salted Bonito (Sarda sarda)

In this study, the fresh meat of bonito (Sarda sarda) was used to make lakerda, which is a type of salted fish (Turkish traditional product). The lakerda was packaged in plastic film (A), vacuumed (VP), placed in modified atmosphere packaging (MAP; M1 = 80%/20% CO2/N2, M2 = 65%/35% CO2/N2, M3 = 30%/60%/10% CO2/N2/O2), and stored at 2 ± 1°C. Microbiological, chemical, sensory, and color analyses were conducted to determine the changes in quality. Total viable bacteria counts did not exceed the limit of consumption (7 log cfu/g) for all groups on Day 31. Total volatile basic nitrogen (TVB-N) and trimethylamine- nitrogen (TMA-N) values of M1, M2, and M3 remained lower than the proposed acceptability limits of 35 and 12 mg N/100 g, respectively, up to 31 days of storage. However, VP lakerda samples exceeded TVB-N limits after 31 days of storage, whereas A lakerda samples exceeded after 8 days of storage. In our study, sensory analysis determined the shelf life of modified atmosphere packaged lakerda. When Group A is compared with the other groups, MAP and VP lengthened the shelf life of lakerda by 23 days.

QUALITY AND SHELF-LIFE ASSESSMENT OF UNDERUTILIZED MARINE GASTROPOD PICKLE

ABSTRACT In India, oysters, clams, mussels and a few gastropods are local delicacies along the coastal region. Of these total catch, few marine gastropods are not utilized by the people because of lack of awareness about the rich nutritive value of the seafood products. Keeping this in mind, an attempt was made to study the shelf life of the pickled product developed from gastropods such as Chicoreus ramosus and Hemifusus pugilinus for a period of 8 and 6 months at ambient temperature (30 ± 2C). The acceptability of gastropod pickles decreased as free fatty acid, trimethylamine nitrogen, total volatile base nitrogen, total plate count and sensory scores increased (P < 0.01 and P < 0.05) at the end of storage period. It is ready-to-eat product, and it can be stored for a period of 8 and 6 months for C. ramosus and H. pugilinus pickle, respectively. PRACTICAL APPLICATIONS Fish pickling has been one of the most popular traditional preservation methods in India. Fishes are mainly preserved by using tamarind, spices, salt and acetic acid as pickling agents. These seafood pickles are safe without any harmful bacteria and have a long shelf-life period for more than 6 months at ambient temperature. However, gastropods are not familiar seafood and are consumed only by certain section of fishing population in India. They are fished mainly for their beautiful shells and operculum. The shells are used as ornaments and also used in lime industry. The operculum is used in Indian traditional medicine. For better utilization of these underutilized marine gastropods, pickled products were developed from Chicoreus ramosus and Hemifusus pugilinus. This present study would reveal the quality of pickled products and concluded that it can be stored for a period of 8 and 6 months.

COMPARISON OF SUPERCHILLING AND FREEZING ON THE MICROSTRUCTURE, MUSCLE QUALITY AND PROTEIN DENATURATION OF GRASS CARP (CTENOPHARYNGODON IDELLUS )

Quality changes in grass carp during superchilled storage at −2C were evaluated in terms of the microstructure, drip loss, pH value, total volatile basic nitrogen (TVB-N), trimethylamine nitrogen (TMA-N), water holding capacity (WHC), salt soluble protein (SSP) and Ca2+-ATPase activity by comparison with frozen storage at −18C. The microstructure of grass carp muscle was seriously damaged with the exhibition of myofibril shrinkage and breakage under frozen storage. Both TVB-N and TMA-N contents in superchilled grass carp were controlled under the acceptable values within 21 days of storage. Significant lower drip loss and higher WHC under superchilled storage was observed compared with frozen storage. Superchilling attenuated the denaturation of myofibrillar protein and the damage of muscle structure associated with freezing, where extractability of SSP and Ca2+-ATPase activity were reduced. A shelf life of 21 days for superchilled grass carp could be estimated by the overall quality evaluation. PRACTICAL APPLICATIONS Traditional frozen fish can be extended for a long time. However, large amounts of water frozen out lead to serious texture change and drip loss after thawing. This study evaluated the potential of superchilling technology to keep the quality of grass carp with little damage caused by freezing storage. The results confirmed that superchilled grass carp could maintain the fresh quality up to 3 weeks. The present study provided a possible application of superchilling for medium period storage of freshwater fish.

DETERMINATION OF THE QUALITY AND SHELF LIFE OF SOUS VIDE PACKAGED WHITING (MERLANGIUS MERLANGUS EUXINUS, NORDMAN, 1840) STORED AT COLD (4C) AND TEMPERATURE ABUSE (12C)

ABSTRACT The effect of storage temperature on the shelf life of sous vide packaged (70C, 10 min) whiting was determined. Samples stored at 12 ± 1C spoiled according to sensory test on the 21st day, when mesophilic aerobic bacteria and trimethylamine nitrogen (TMA-N) exceeded the limits. However, their consumption is not advisable after 15 days because psychrophilic counts exceeded the recommended limits at that day. In cold storage (4 ± 1C) Total volatile basic nitrogen and TMA-N, values of the samples exceeded the limits on the 42nd day. However, because samples spoiled according to sensory test, and mesophilic and psychrophilic aerobic bacterial counts were above the limits, shelf life was considered as 35 days. Sous vide cooking at 70C for 10 min could extend significantly the shelf life of whiting both at 4C and temperature-abuse conditions (12C). PRACTICAL APPLICATIONS Sous vide is a long established but relatively little-known cooking process. The data regarding the effect of storage temperature on the shelf life and quality of sous vide fish are very limited. Therefore, this study aimed to determine the sensory, microbiological and chemical quality of sous vide packaged whiting during refrigerated storage (4 ± 1C) and temperature-abuse temperature conditions (12 ± 1C). The results of this study can be utilized by researchers in future studies as well as by manufacturers to determine the processing and storage conditions of sous vide fish.

Control of the potential health hazards of smoked fish by gamma irradiation

This study aims to control the presence of Listeria monocytogenes and Vibrio parahaemolyticus and the formation of biogenic amines in cold-smoked salmon by gamma irradiation. Irradiation at doses of 3 and 1kGy inactivated 6.59 and 6.05log cfu/g of L. monocytogenes and V. parahaemolyticus in the inoculated samples, respectively. Furthermore, irradiation of the un-inoculated samples significantly decreased their microbial populations of mesophilic aerobic bacteria, anaerobic bacteria, psychrophilic bacteria, lactic acid bacteria, and molds and yeasts. The Enterobacteriaceae were almost undetectable in samples irradiated at 2kGy dose. The concentrations of biogenic amines significantly decreased in the irradiated samples due to microbial inactivation. However, irradiation of samples had no significant effects on their moisture and salt contents as well as on their pH values, total volatile base nitrogen, and trimethylamine nitrogen contents, but significantly decreased their amounts of phenolic compounds and increased their levels of thiobarbituric acid reactive substances. Moreover, irradiation treatments at doses up to 3kGy showed no significant effect on the sensory acceptability of samples. Therefore, gamma irradiation at dose of 3kGy can be successfully applied to provide significant improvement in the safety of cold smoked salmon with respect to L. monocytogenes, V. parahaemolyticus, and biogenic amines without adverse effects on chemical or sensory quality attributes of the product.