Combined effect of MAP and thyme essential oil on the microbiological,chemical and sensory attributes of organically aquacultured sea bass (Dicentrarchus labrax) fillets

The present study evaluated the combined effect of Modified Atmosphere Packaging (MAP) using two different gas mixtures (40% CO₂/50% N₂/10% O₂; treatment M1, 60% CO₂/30% N₂/10% O₂, treatment M2), and thyme oil (0.2% v/w, T) used as a natural preservative, on the quality and shelf life extension of fresh filleted sea bass, product of organic aquaculture, during refrigerated storage (4± 0.5 °C), for a period of 21 days. Aerobically packaged sea bass fillets (A) were used as control samples. The dominant bacteria in the microflora of sea bass fillets, irrespective of treatment, were the pseudomonads and the H₂S-producing bacteria while lactic acid bacteria were also part of the dominant microflora. Total viable counts for fresh sea bass fillets stored aerobically exceeded 7 log CFU/g after 7 days, while treatments A+T, M1, M2 and M2+T reached the same value on days 9, 10, 12 and 19, respectively. Among the chemical indices determined, TBA values were within the good quality limits (2–4 mg MDA/kg), during the sensory shelf lives of sea bass samples, irrespective of treatment. TVB-N proved to be a suitable index for the spoilage of sea bass fillets stored at 4 °C. Samples A and A+T, M1, M2, M2+T exceeded the proposed upper TVB-N acceptability limit (10 mg N/100 g) on days 6, 8, 9, 13 and 17 of storage respectively. TMA-N values of the samples A, A+T and M1, M2, M2+T exceeded the proposed limit (4 mg N/100 g) on days 6, 9, 9–10, 13 and 19 of storage, respectively, and correlated well with the microbiological data, indicating that along with TVB-N, TMA-N may serve as a useful index for sea bass fillets spoilage. As regards sensory evaluation, the presence of thyme oil proved to improve the sensory quality of sea bass fillets when used in combination with MAP2, providing a shelf life of 17 days as compared to 6 days of the control samples.     

Combined effect of vacuum-packaging and oregano essential oil on the shelf-life of Mediterranean octopus (Octopus vulgaris) from the Aegean Sea stored at 4 °C

The present study evaluated the use of vacuum packaging (alone) or with addition of oregano essential oil (EO), as an antimicrobial treatment for shelf-life extension of fresh Mediterranean octopus stored under refrigeration for a period of 23 days. Four different treatments were tested: A, control sample; under aerobic storage in the absence of oregano essential oil; VP, under vacuum packaging in the absence of oregano essential oil; and VO1, VO2, treated samples with oregano essential oil 0.2 and 0.4% (v/w), respectively, under VP. Of all the microorganisms enumerated, Pseudomonas spp., H₂S-producing bacteria and lactic acid bacteria (LAB) were the groups that prevailed in octopus samples, irrespective of antimicrobial treatment. With regard to the chemical freshness indices determined, thiobarbituric acid (TBA) values were low in all octopus samples, as could have been expected from the low fat content of the product. Both trimethylamine nitrogen (TMA-N) and total volatile basic nitrogen (TVB-N) values of oregano treated under VP octopus samples were significantly lower compared to control samples during the entire refrigerated storage period. Based primarily on sensory evaluation (odor), the use of VP, VO1 and VO2 extended the shelf-life of fresh Mediterranean octopus by ca. 3, 11 and 20 days, respectively.     

Combined effect of light salting,modified atmosphere packaging and oregano essential oil on the shelf-life of sea bream (Sparus aurata): Biochemical and sensory attributes

The combined effect of modified atmosphere packaging (MAP: 40% CO₂/30% O₂/30% N₂) and oregano essential oil, on the shelf-life of lightly salted cultured sea bream (Sparus aurata) fillets stored under refrigeration was studied. Quality assessment was based on sensory analysis and biochemical indices determination. Total volatile basic nitrogen (TVBN) and trimethylamine nitrogen (TMAN) values were higher in sea bream fillets stored in air followed by salted fillets stored in air. For salted sea bream fillets stored under MAP the inhibition in the TVBN and TMAN values was evident in the order MAP < MAP/0.4% (v/w) oregano oil < MAP/0.8% (v/w) oregano oil indicating the preservative effect of oregano oil. Salting had a noticeable preservative effect but produced an increase in the 2-thiobarbituric acid (TBA) values while oregano oil had a strong antioxidant activity giving the lowest TBA values. All raw sea bream fillet samples received acceptable sensory scores during the first 15–16 days of storage. The salted samples remained acceptable up to ca. 20–21 days while the MAP salted samples up to ca. 27–28 days of storage. The oregano oil addition in MAP salted samples yielded a distinct but pleasant flavor and contributed to a considerable slower process of fish spoilage given that the fillets treated with 0.8% (v/w) oregano oil were still sensory acceptable after 33 days of storage. The preservative effect was greater as the oregano oil concentration was greater.     

Potential of oregano essential oil and MAP to extend the shelf life of fresh swordfish: a comparative study with ice storage

ABSTRACT:  The present study evaluated the effect of modified atmosphere packaging (MAP, 5% O₂/50% CO₂/45% N₂; treatment M), the addition of oregano oil (0.1%, v/w; treatment AO) as a natural preservative, as well as their combination (treatment MO) on the quality and shelf life extension of fresh Mediterranean swordfish fillets during a refrigerated storage (4 °C) period of 18 d. Simultaneously, swordfish fillets were stored under aerobic conditions (control treatment A, 4 °C) and on ice (usual commercial method of preservation, treatment I, 0 °C). Among the 5 treatments examined in the present study, the most effective one to inhibit the microbial and sensory spoilage proved to be the MO treatment, achieving a shelf life extension of 8 to 9 d. The dominant bacteria in the microflora of swordfish, irrespective of treatment, were the Pseudomonads and the H₂S-producing bacteria, while both lactic acid bacteria (LAB) and the Enterobacteriaceae produced the lowest populations in swordfish samples kept on ice. Among the chemical indices examined, thiobarbituric acid (TBA) values showed no specific trend of lipid oxidation for swordfish, irrespective of treatment. Final trimethylamine nitrogen (TMA-N) and total volatile basic nitrogen (TVB-N) values for treatments, A, AO, M, and MO ranged between 1.33 and 14.29 mg N/100 g and 14.11 to 55.52 mg N/100 g, respectively, whereas for I samples they remained almost unchanged during storage. Sensory analysis (taste attribute) correlated well with microbiological analysis, indicating a shelf life of approximately 5 to 6 d for control, 10 to 11 d for AO, 12 d for I, 13 d for M, and 14 d for MO samples.     

Effect of modified atmosphere and active packaging on the shelf-life of fresh bluefin tuna fillets

The aim of this work was to study the influence of the combined use of MAP and antioxidant-based active packaging on the shelf-life of fresh bluefin tuna fillets stored at 3 °C. Active packaging films were produced by embedding α-tocopherol into an unstabilized low density polyethylene (LDPE) matrix at three concentrations (0.1%, 0.5%, 1%). α-Tocopherol release kinetics, in vitro antioxidant activity, oxygen permeability and crystallinity degree were determined to characterize the film. Preliminary shelf-life tests were performed to select critical quality indices, the best gas composition and the best α-tocopherol concentrations in the active film. Then, the effectiveness of the chosen active packaging film in combination with MAP was assessed by monitoring critical quality indices of fresh bluefin tuna fillet during storage at 3 °C for 18 days. Obtained results showed that (i) 100% N₂ atmosphere has a protective effect on haemoglobin and lipid oxidation processes monitored, (ii) active film is able to reduce fat oxidation, (iii) the combined effect of MAP and active packaging can be considered a valuable tool to increase the shelf-life of raw fish products.     

Shelf-life of chilled fresh Mediterranean swordfish (Xiphias gladius) stored under various packaging conditions: microbiological, biochemical and sensory attributes

The present work evaluated the effect of air, vacuum and modified atmosphere packaging (MAP) on the shelf-life of chilled Mediterranean swordfish (Xiphias gladius). Fresh swordfish slices were stored in air, under vacuum and MAP (40%/30%/30%, CO(2)/N(2)/O(2)) under refrigeration (4 degrees C) for a period of 16 days. Of the three treatments used (vacuum, MAP and air), both MAP and vacuum packaging (VP) were the most effective for inhibiting growth of aerobic microflora in swordfish samples until days 9-10 of refrigerated storage. Of the microbial species determined, both Pseudomonas spp. and H(2)S-producing bacteria (including Shewanella putrefaciens) were dominant in swordfish samples stored in air, whereas growth of these species was partly inhibited under VP and MAP conditions. Lactic acid bacteria (LAB) and Enterobacteriaceae were also found to be members of the final swordfish microbial flora, irrespective of packaging conditions throughout the entire storage period. Of the chemical freshness indices determined, thiobarbituric acid (TBA) values were variable in swordfish samples, indicative of no specific oxidative rancidity trend. Trimethylamine nitrogen (TMA-N) values of swordfish samples stored in air, under VP and MAP exceeded the limit value of 5mgN/100g fish muscle after days 7, 8-9 and 11 days of storage, respectively. In a similar trend, total volatile basic nitrogen (TVB-N) for swordfish samples stored in air, under VP and MAP exceeded the limit value of 25mgN/100g fish muscle after 7-8, 10 and 12 days of storage, respectively. Sensory analyses (odor and taste attributes) indicated a shelf-life of ca. 7 days for air, 9 days for VP and 11-12 days for the MA-packaged swordfish samples.     

The effects of thyme (Thymus vulgaris L.) oil concentration on liquid-smoked vacuum-packed rainbow trout (Oncorhynchus mykiss Walbaum, 1792) fillets during chilled storage

This study examined the effects of thyme oil on chemical properties, microbiological changes, and sensory quality in vacuum-packed liquid-smoked rainbow trout fillets under chilled storage. After 150 days of storage, the total volatile basic nitrogen (TVB-N) values were 30.52, 27.5 and 39.43 mg/100 g, and total viable counts (TVC) were 5.34, 4.96 and 5.53, for thyme oil additions of 10 (T10), 50 (T50) and 0 (control; T0) mL/L brine, respectively. The highest acceptable TVB-N value was adopted as 30 mg /100 g, corresponding to shelf lives of 135, 150, and 105 days for T10, T50, and T0, respectively. T50 addition of thyme oil to liquid-smoked rainbow fillets extended shelf life T10 and T50, gave acceptable sensory quality and limited microbiological growth during chilled storage.     

The effects of modified atmosphere packaging, EDTA and oregano oil on the quality of chicken liver meat

Fresh chicken liver meat was packaged in air or under modified atmosphere packaging (MAP; 30%CO₂/70%N₂) and stored under refrigeration (4 °C). The following treatments were used: A (control samples, air packaging), AE [(EDTA (20 mM), air packaging)], M (MAP), ME (EDTA, stored under MAP), MER1 [(EDTA, oregano oil (0.1% v/wt), stored under MAP)] and MER2 [(EDTA, oregano oil (0.3% v/wt), stored under MAP)]. Quality evaluation of product stored under above packaging conditions and treated with EDTA and oregano oil was conducted using microbiological, chemical and sensory analyses. Based on mesophilic total viable counts (TVC) a microbiological shelf-life extension of 7, 9, 15 or > 15 days was obtained for M, ME, MER1 or MER2 liver samples, respectively, compared to the control's (A) shelf-life of 3 days. Air-packaged liver samples showed higher pH values in the first 8 days of storage compared to M, ME, MER1 and MER2 samples, with the latter showing a significant decrease at the end of the storage period. Interestingly, the presence of the oregano oil in MER1 and MER2 liver resulted in a lower production of TBA compared to all other samples. Based on sensory analysis, MER1 and MER2 extended the shelf-life of chicken liver by 14–15 days, while treatments M and ME by 7 and 9 days, respectively. Our results support the hypothesis that the shelf-life of chicken liver meat may substantially be extended (by almost 3 times the usual product's shelf-life using a natural antimicrobial combination (EDTA, oregano oil and MAP).     

Effects of chilled storage on quality of vacuum packed meagre fillets

The aim of this study was to experimentally assess several quality indices of meagre Argyrosomus regius (Asso, 1801) fillets packed in air (AP) and vacuum (VP) stored chilled (+4 °C) for up to 13 days. Considering our experimental data on concentration of bacterial counts, shelf-life is estimated at ca. 6 days for AP fillets and an additional 3–5 days for VP meagre fillets. Total volatile basic nitrogen (TVB-N) and trimethylamine (TMA-N) did not reach the regulated limits (25–35 mg/100 g chilled fish). The models implemented in the software Seafood Spoilage and Safety Predictor predicted a relatively shorter shelf-life of 4.8–6.9 days for fish stored in air at +4 °C when compared to AP and VP fillets. Empirical data and the models implemented in the software were used to predict the shelf-life of fillets if packaged under different modified atmospheres (MAP). Chilled, MAP fillets are likely to have a longer shelf-life than AP or VP samples if equilibrium CO₂ concentration is substantially high.     

竹叶抗氧化物结合不同包装方式对鲜罗非鱼片保鲜效果的影响

以感官特性、菌落总数、汁液流失率、pH值、挥发性盐基氮(total volatile basic nitrogen,TVB-N)值及硫代巴比妥酸(2-thiobarbituric acid,TBA)值为评价指标,研究竹叶抗氧化物结合不同包装方式对鲜罗非鱼片保鲜效果的影响。结果表明,竹叶抗氧化物对鲜罗非鱼片具有良好的抗菌和抗氧化作用,0.1 g/100 m L竹叶抗氧化物处理的罗非鱼片比对照组货架期延长了4~6 d;竹叶抗氧化物结合真空包装或气调包装均能够明显抑制微生物生长繁殖,降低TVB-N值和TBA值,减缓感官品质的下降速率,延长货架期;冰藏条件下各组鲜度指标均明显优于冷藏条件,冰藏条件下0.1 g/100 m L竹叶抗氧化物结合真空包装或气调包装处理的罗非鱼片保鲜效果提高明显,货架期增加至18 d。研究表明,竹叶抗氧化物结合真空包装或气调包装在鲜罗非鱼片保鲜方面具有应用的潜力。     

Shelf-life extension and quality attributes of the whey cheese “Myzithra Kalathaki” using modified atmosphere packaging

The present work evaluated the effect of modified atmosphere packaging (MAP) on quality characteristics and shelf-life extension of the whey cheese “Myzithra Kalathaki” using microbiological, chemical and sensory analyses. Myzithra cheese was packaged in four different atmospheres: vacuum, 20% CO₂/80% N₂ (M₁), 40% CO₂/60% N₂ (M₂) and 60% CO₂/40% N₂ (M₃); identical cheese samples were packaged in air, taken as controls. All cheese samples were kept under refrigeration (4±0.5 °C) for 45 days. Of the four atmospheres, the M₂ and M₃ gas mixtures were the most effective for inhibiting growth of aerobic microflora and psychrotrophs in cheese samples until days 40 and 33 of refrigerated storage, respectively. Lactic acid bacteria (LAB) were part of the cheese microflora becoming dominant toward the end of the storage period regardless of packaging conditions. Enterobacteriaeceae were also part of the cheese microflora being effectively inhibited after day 35 of storage. Molds and yeasts were also totally inhibited by MAP (M₂ and M₃) gas mixtures throughout the entire storage period. Of the chemical quality indices determined, lipid oxidation varied below 0.005 absorbance at 532 nm for all treatments, except control samples for which absorbance values of 0.02 were recorded after 35 days of storage. Lipolysis did not vary significantly with type of packaging treatment while proteolysis values showed and increasing trend up to day 25 of storage and then decreased toward the end of the storage period. Sensory evaluation (odour and taste) showed that Myzithra cheese packaged under MAP (M₂ and M₃) retained good sensory characteristics for 30 days of storage while control samples were sensorily unacceptable after 10-12 days of storage.     

Sensory,physical, chemical and microbiological changes in aquacultured meagre (Argyrosomus regius) fillets during ice storage

Commercial-sized meagre fillets were stored on ice at 4 °C for 18 days, in order to evaluate the loss of quality and freshness that occurs over this period of time. Physicochemical (pH, thiobarbituric acid (TBA), total volatile basic nitrogen (TVBN), trimethylamine (TMA), water activity, water-holding capacity, colour, texture and fatty acid profile), sensory and microbiological analyses were carried out at 0, 4, 7, 11, 14 and 18 days of storage. As part of the sensory analysis, attributes associated with fillet appearance, odour and texture were examined. Variations in pH, TBA, TVBN and TMA were observed throughout the storage period, although only TBA displayed a significant correlation with time (r = 0.96). L^∗ and b^∗ values increased, and the chroma and hue values decreased, reflecting the colour changes experienced by the fillets over time. With regards to the texture profile, hardness was significantly correlated with time (−0.68). All the sensory analysis attributes exhibited significant variations and correlations close to 1.00 with storage time, which is a reflection of the fillets’ loss of freshness. The correlation coefficients between aerobic mesophilic and psychrophilic bacteria, enterobacteria and coliform counts on the one hand and storage time on the other were also very high (0.99–1.00). A regression analysis using the acceptability limit set by the ICMSF standard (1986) for total aerobic mesophilic counts (7 log cfu/g) yielded a shelf-life for meagre fillets of 9 days. The TBA, sensory and microbiological analyses displayed very strong correlations with storage time, and they may be considered suitable indicators for evaluating meagre fillet spoilage during refrigerated storage.     

A new technology for fish preservation by combined treatment with electrolyzed NaCl solutions and essential oil compounds

This study was undertaken to establish a new technology, using pre-treatment with electrolyzed NaCl solutions and essential oil compounds, to extend the shelf-life of carp fillets. Samples of skinless carp fillets were treated with 100-fold (by weight) of electrolyzed NaCl solutions [cathodic solution, EW(−) and/or anodic solution, EW(+)] and 1% oil (0.5% carvacrol + 0.5% thymol) [1%(C + T)]. Then chemical [pH, volatile basic nitrogen, peroxide value, and thiobarbituric acid], microbiological (total viable count) and sensory analyses were used to evaluate the preservative effect of this new technology during storage at 5 and 25 °C. Our results from the chemical assays indicated that EW(−), followed by EW(+) and subsequently 1%(C + T) [EW(−)/EW(+)/1%(C + T)], significantly suppressed the lipid oxidation compared with other treatments. Data from sensory evaluation and microbiological assay showed that treatment with EW(−)/EW(+)/1%(C + T) extended the shelf-life of carp fillets to 16 and 1.3 days compared with 4 and 0.3 days for the control samples during storage at 5 and 25 °C, respectively.     

Shelf-life extension of refrigerated Mediterranean mullet (Mullus surmuletus) using modified atmosphere packaging

The present work evaluated the quality and freshness characteristics and the effect of modified atmosphere packaging (MAP) on the shelf-life extension of refrigerated Mediterranean mullet using microbiological, biochemical, and sensory analyses. Fresh open sea red mullet (Mullus surmuletus) were packaged in four different atmospheres: M1, 10%/20%/70% (O2/ CO2/N2); M2, 10%/40%/50% (O2/CO2/N2); M3, 10%/60%/30% (O2/CO2/N2); identical fish samples were packaged in air. All fish were kept under refrigeration (4 +/- 0.5 degrees C) for 14 days. Of the three gas atmospheres, the 10%/40%/50% (M2) and 10%/ 60%/30% (M3) gas mixtures were the most effective for inhibiting growth of aerobic microflora in mullet samples until day 10 of refrigerated storage. H2S-producing bacteria and pseudomonads were part of the mullet microflora and their growth was partly inhibited under MAP conditions. Between these two bacterial groups, H2S-producing bacteria (including Shewanella putrefaciens) were dominant toward the end of the storage period, regardless of the packaging conditions. Brochothrix thermosphacta and lactic acid bacteria were found to be members of the final microbial flora of MAP and air-packaged mullet, whereas the Enterobacteriaceae population was lower than other bacterial groups. Of the chemical freshness indices determined, thiobarbituric acid values were variable in mullet samples irrespective of packaging conditions indicative of no specific oxidative rancidity trend. Based on sensorial data and aerobic plate count, trimethylamine nitrogen and total volatile basic nitrogen limit values in the range of ca. 15 to 23 and 52 to 60 mg N/100 g of fish muscle were obtained, respectively, for mullet packaged under modified atmosphere and air. Sensory analyses (odor and taste attributes) showed that the limit of sensorial acceptability was reached after ca. 6 days for the samples packaged in air, 8 days for the M1 and M3 samples, and after 10 days for the M2 samples. Respective shelf-life extension for fresh whole mullet was ca. 2 days (M1 and M3 gas mixtures), and 4 days (M2 gas mixture).     

Quality and shelf-life of washed fresh-cut asparagus in modified atmosphere packaging

Fresh-cut asparagus is one of the most popular fresh vegetables for healthy consumption. However, the level of microbial load in the raw vegetable can cause food poisoning and shorten its shelf-life of asparagus. The objectives of this work were to determine the effect of chlorinated and ozonated water in the washing process to reduce the microbial load on fresh green asparagus and the effect of modified atmosphere packaging (MAP) on asparagus quality. Washing at 10 °C for 15 min with chlorinated water (100 mg/L free Cl₂) reduced aerobic plate count which had higher efficiency on microbial reduction than the use of ozonated water (0.1 mg/L O₃). No significant differences on the amount of Escherichia coli contamination among washing methods were found. Asparagus in modified atmosphere packaging retarded the deterioration process. Changes in hue angle followed a first-order kinetic reaction. Temperature dependence of the kinetic rate constant during storage time of asparagus obeyed the Arrhenius relationship with an activation energy (E_a) 29.33 ± 4.60 kJ/mol. The shelf-life prediction equation was related well with real practice. The combination of appropriate washing process and MAP increased the food safety, maintained the quality and prolonged the shelf-life of asparagus.     

Shelf life extension of Atlantic pomfret (<Emphasis Type="Italic">Brama brama</Emphasis>) fillets by packaging under a vacuum-skin system

The present study was aimed at improving the commercialisation strategies of Atlantic pomfret (Brama brama), a medium-size fish commonly consumed as fresh fish. With this purpose, an innovative vacuum-skin packaging system including a surface thermal treatment was tested on Atlantic pomfret fillets stored at 4 °C for up to 19 days. The results were compared with traditional vacuum packaging carried out in parallel. The investigation of three sensory features (flesh appearance, flesh odour and flesh colour), five biochemical parameters (pH, free fatty acids, conjugated dienes, fluorescent compounds and total volatile bases) and three microbiological parameters (aerobic mesophiles, anaerobes and coliforms) was carried out in both batches. The vacuum-skin packaging system showed an interesting preservative effect leading to a significantly higher quality retention and longer shelf life (12 days) with respect to both traditional vacuum packaging (7 days) and a control batch kept in air (5 days). From the results obtained, it is concluded that the vacuum-skin system allows an extended shelf life and a better maintenance of the sensory, biochemical and microbiological quality of Atlantic pomfret fillets. This innovative packaging system might be applied to other kinds of fish species to stimulate the marketing opportunities.     

Chitosan dipping or oregano oil treatments, singly or combined on modified atmosphere packaged chicken breast meat

The present study examined the effect of natural antimicrobials: chitosan, oregano and their combination, on the shelf-life of modified atmosphere packaged chicken breast meat stored at 4°C. Treatments examined in the present study were the following: M (control samples stored under modified atmosphere packaging), M-O (samples treated with oregano oil 0.25% v/w, stored under MAP), M-CH (samples treated with chitosan 1.5% w/v, stored under MAP) and M-CH-O (treated with chitosan 1.5% w/v and oregano oil 0.25% v/w, stored under MAP). Treatment, M-CH-O, significantly affected mesophilic Total Plate Counts (TPC), lactic acid bacteria (LAB), Brochothrix thermosphacta, Enterobacteriaceae, Pseudomonas spp., and yeasts-moulds during the storage period. Lipid oxidation (as determined by MDA values) of control and treated chicken samples was in general low and below 0.5 mg MDA/kg, showing no oxidative rancidity during the storage period. Addition of chitosan to the chicken samples produced higher (P<0.05) lightness (L*) values as compared to the control samples. The results of this study indicate that the shelf-life of chicken fillets can be extended using, either oregano oil singly, and/or chitosan, by approximately 6 (M-O) and >15 (M-CH and M-CH-O) days. Interestingly, chitosan (M-CH) or chitosan-oregano (M-CH-O) treated chicken samples were sensorially acceptable during the entire refrigerated storage period of 21 days. It is noteworthy that the presence of chitosan in M-CH and M-CH-O samples did not negatively influence the taste of chicken samples, with M-CH samples receiving a higher score (compared to M-CH-O), probably as a result of a distinct and "spicy" lemon taste of chitosan, that was well received by the panelists. Based primarily on sensory data (taste attribute) M-CH and M-O treatments extended the shelf-life of chicken fillets by 6 days, while M-CH-O treatment resulted in a product with a shelf-life of 14 days, maintaining acceptable sensory characteristics.     

Effect of modified atmosphere packaging and vacuum packaging on the shelf-life of refrigerated chub mackerel (<Emphasis Type="Italic">Scomber japonicus</Emphasis>): biochemical and sensory attributes

The effect of modified atmosphere packaging (MAP 1: 70% CO₂/30% N₂ and MAP 2: 50% CO₂/30% N₂/20% O₂) and vacuum packaging (VP), on the shelf-life of chub mackerel (Scomber japonicus) fillets stored under refrigeration was studied. Quality assessment was based on sensory analysis and biochemical indices determination. Increase in total volatile basic nitrogen (TVBN) and trimethylamine nitrogen (TMAN) followed the order: MAP 1 < MAP 2 < VP < air (control samples). The presence of oxygen into the fish package (air or MAP) resulted in an increase in the 2-thiobarbituric acid (TBA) values in comparison with samples packaged in the absence of oxygen. The most effective MAP used was MAP 1 which contributed to a considerably slower rate of fish spoilage. Based primarily on odour scores it was observed that raw chub mackerel fillets stored in the presence of air remained acceptable up to ca. 11 days, VP and MAP 2 samples up to ca. 15–16 days, while MAP 1 samples up to ca. 20–21 days of storage. On the other hand, flesh texture and flesh colour of all packaged samples received scores above or equal than the acceptability limit up to ca. 13–14 days of storage.     

Combined effects of salting,oregano oil and vacuum-packaging on the shelf-life of refrigerated trout fillets

The present study evaluated the effect of salt, oregano essential oil (EO) and packaging on fresh rainbow trout fillets during storage at 4 °C. Treatments included the following: A1 (control samples, unsalted: air packaged), A2 (salted: air packaged), VP1 (salted, vacuum packaged), VP2 (salted, vacuum packaged with added oregano EO 0.2% v/wt), and VP3 salted, vacuum packaged with added oregano EO 0.4% v/wt). Lactic acid bacteria (LAB) (to a greater extent), followed by H₂S-producing bacteria (including Shewanella putrefaciens), Pseudomonas spp. and Enterobacteriaceae reached higher populations in A1, A2 (as compared to VP1, VP2 and VP3) trout samples. Treatments VP1, VP2 and VP3 produced significantly lower (P < 0.05) total volatile basic nitrogen (TVBN) and trimethylamine nitrogen (TMAN) values as compared to the A1 and A2 samples after day 6 and until end of storage period. Changes in thiobarbituric acid values (TBA) values for A1, A2, VP1, VP2 and VP3 samples were variable, indicative of no specific trend in trout samples, irrespective of packaging in the absence and/or presence of salt and oregano EO. As determined by sensory analysis (overall acceptability attribute) the observed shelf-life of trout fillets was longest for VP2 (16–17 days) followed by VP1 (14 days), A2 (8 days) and control (A1) samples (5 days). The presence of salt and oregano oil (0.2%) in cooked VP1 trout samples produced a distinct but sensorially acceptable pleasant odor, well received by the panellists, in contrast to the combined effect of salt and oregano oil at the higher concentrations (0.4% v/wt) used. Addition of salt (treatment VP1) extended the product's shelf-life by 9 days, whereas the combination of salt, oregano EO (0.2% v/wt) under VP conditions (treatment VP2) resulted in a significant shelf-life extension of trout fillets (11–12 days) according to sensory data, as compared to the control sample, kept under aerobic conditions.     

Combined effect of freeze chilling and MAP on quality parameters of raw chicken fillets

The effect of short-term frozen storage prior to thawing on the quality of freeze-chilled chicken fillets was investigated, as was the effect of modified atmosphere packaging (MAP). Four process treatments were used: (1) fresh chicken chilled at 4 degrees C without previous freezing, (2) freeze-chilled for 7 days and thawed at 4 degrees C, (3) chilled at 4 degrees C packaged under MAP (70% N(2)-30%CO(2)), and (4) packaged under MAP, freeze-chilled for 7 days and thawed at 4 degrees C. Microbiological, chemical and sensory analyses were conducted on samples for a period up to 15 days. Freeze-chilled fillets gave a lower total viable count (TVC) at a given sampling day than chilled fillets. MAP, as expected, delayed microbial growth. The Pseudomonads were the dominant microbial species in fillets under aerobic conditions. MAP reduced the populations of Pseudomonads by 2-4 log cfu/g. Lactic acid bacteria (LAB) and Enterobacteriaceae increased progressively for all treatments throughout storage. Yeasts and molds were inhibited by MAP and by freeze chilling. Total volatile basic nitrogen (TVB-N) values increased rapidly for the chilled fillets but remained significantly lower for the freeze-chilled and the MA-packaged samples. MAP and especially freeze chilling enhanced drip loss. MAP did not affect redness or yellowness of product while freeze chilling decreased product redness. Lightness was not affected by either MAP or freeze chilling. Based on taste, which proved to be the most sensitive sensory attribute, shelf life of product ranged from 6 to 7 days for all treatments leading to the conclusion that freeze chilling is a suitable technology for fresh chicken fillets enabling their distribution as a frozen product and upon subsequent thawing at their final destination, their retail display as chilled products. MAP in combination with freeze chilling had a negligible effect on product quality.