Effect of gutting on microbiological,chemical, and sensory properties of aquacultured sea bass (Dicentrarchus labrax) stored in ice

The effect of gutting on microbiological, chemical, and sensory properties of aqua-cultured sea bass (Dicentrarchus labrax) stored in ice was studied. Pseudomonads and H₂S-producing bacteria (including Shewanella putrefaciens) were the dominant bacteria at the end of the 16-day storage period in ice for both whole ungutted and gutted sea bass. Brochothrix thermosphacta and Enterobacteriaceae were also found in the spoilage microflora of ungutted and gutted sea bass but their counts were always less than those of Pseudomonads and H₂S-producing bacteria. Bacterial counts of whole ungutted sea bass were always higher than those obtained for gutted sea bass samples. Mesophilic counts for gutted and ungutted fish exceeded 7 log cfu g⁻¹ after 9 and 15 days of ice storage, respectively. Of the chemical indicators of spoilage, TMA values of ungutted sea bass increased very slowly whereas for gutted samples higher values were obtained reaching a final value of 0.73 and 4.39 mg N 100 g⁻¹, respectively (day 16). TVB-N values showed no significant increase for whole ungutted sea bass during storage reaching a value of 27.7 mg N 100 g⁻¹ (day 16) whereas for gutted fish 36.9 mg N 100 g⁻¹ was recorded. TBA values remained low for ungutted sea bass samples until day 16 of storage, whereas for gutted fish were variable. Of the chemical indices used, none proved useful means of monitoring early ungutted and gutted sea bass freshness in ice. Sensory assessment using the EC freshness scale gave a grade E for up to 5 days for the ungutted sea bass, a grade A for a further 2 days and a grade B for an additional 4 days, after which sea bass was graded as C (unfit). Gutted sea bass was given a grade E for up to 3 days, a grade A for the 4–7th days, and a grade B for the 8–10th days of storage, whereas on day 11 it was graded as unfit. Acceptability scores for odor, taste and texture of cooked ungutted and gutted sea bass decreased with time of storage. Results of this study indicate that the shelf-life of whole ungutted and gutted sea bass stored in ice as determined by the overall acceptability sensory scores and microbiological data is 13 and 8 days, respectively.     

Microbiological,chemical and sensory changes of whole and filleted Mediterranean aquacultured sea bass (Dicentrarchus labrax) stored in ice

The effect of filleting on the microbiological, chemical and sensory properties of aquacultured sea bass (Dicentrarchus labrax) stored in ice was studied. Pseudomonads, H₂S‐producing bacteria (including Shewanella putrefaciens) and Brochothrix thermosphacta were the dominant bacteria at the end of the 16 day storage period in ice for both whole ungutted and filleted sea bass. Enterobacteriaceae were also found in the spoilage microflora of whole ungutted and filleted sea bass, but their counts were always lower than those of pseudomonads, H₂S‐producing bacteria (including S putrefaciens) and B thermosphacta. Total viable counts for whole ungutted sea bass were always lower than those for filleted sea bass samples. Of the chemical indicators of spoilage, TMA (trimethylamine) values of whole ungutted sea bass increased very slowly, whereas significantly higher values were obtained for filleted samples, with respective values of 0.253 and 1.515 mg N per 100 g muscle being reached at the end of their shelf‐life (days 13 and 9 respectively). TVB‐N (total volatile basic nitrogen) values showed a slight increase for whole ungutted sea bass during storage, reaching a value of 26.77 mg N per 100 g muscle (day 13), whereas for filleted fish a corresponding value of 26.88 mg N per 100 g muscle was recorded (day 9). TBA (thiobarbituric acid) values increased slowly for whole ungutted and filleted sea bass samples throughout the entire storage period, reaching final values of 4.48 (day 13) and 13.84 (day 9) mg malonaldehyde kg^?1 respectively. Sensory assessment of raw fish using the EC freshness scale gave a grade E for up to 5 days for whole ungutted sea bass, a grade A for a further 4 days and a grade B for an additional 4 days, after which sea bass was graded as C (unfit). Overall acceptability scores for odour, taste and texture of cooked whole ungutted and filleted sea bass decreased with increasing time of storage. The results of this study indicate that the shelf‐life of sea bass stored in ice, as determined by overall acceptability sensory scores and microbiological data, is 8–9 days for filleted and 12–13 days for whole ungutted fish. Copyright © 2003 Society of Chemical Industry     

Chemical and microbial analyses of squid muscle (Loligo plei) during storage in ice

Chemical and microbial changes in squid muscle (Loligo plei) and the efficiency of chemical indices for freshness evaluation were investigated during storage in contact ice (CI) and non-contact ice (NC). Psychrotrophic bacterial counts and non-protein nitrogen, free amino acids, trimethylamine, volatile basic nitrogen (VBN), urea and free tryptophan contents were periodically determined in squid muscle. No difference (P < 0.05) was detected between treatments regarding the increase of psychrotrophic bacterial counts in squid muscle during storage. The leaching of soluble compounds in CI treatment drastically affected the efficiency of the chemical indices for freshness. Trimethylamine and VBN contents in squid muscle increased only after day 9 and no increase was observed in free tryptophan and urea contents in CI treatment. In the NC treatment the contents of VBN and trimethylamine slowly increased during the first days of storage whereas free tryptophan and urea contents markedly increased during the whole storage. Free tryptophan and urea can be useful freshness indices for L. plei in storage conditions wherein leaching have been minimized.     

Relation of biogenic amines with microbial and sensory changes of whole and filleted freshwater rainbow trout (Onchorynchus mykiss) stored on ice

The biogenic amine (BA) content of whole and filleted rainbow trout was monitored during ice storage for a period of 18 days and related to respective microbial and sensorial changes occurring during the same period. Eight amines, namely, putrescine, cadaverine, tyramine, spermidine, tryptamine, beta-phenylethylamine, spermine, and histamine, were determined. Agmatine was not detected in any of the fish samples. In all cases, concentration of BAs was higher (P < 0.05) in filleted compared with whole trout samples. Pseudomonads, H2S-producing bacteria, and, to a lesser extent, Enterobacteriaceae were the dominant microorganisms in both whole and filleted trout. Higher populations (P < 0.05) of these microorganisms were present in filleted trout compared with whole fish samples. Of the BAs determined, concentration of putrescine, cadaverine, spermidine, tryptamine, and beta-phenylethylamine increased steeply in both whole and filleted trout between days 15 and 18 of storage when pseudomonads and H2S-producing bacteria reached approximately 10(6) to 10(7) CFU/g. For the rest of the BAs, including tyramine, histamine, and spermine, a stepwise increase was recorded throughout the entire storage period. Interestingly, Enterobacteriaceae counts remained below 10(6) throughout the entire storage period, accounting for the lower production of histamine. A putrescine value of 13 to 14 mg/kg and a spermidine value of approximately 7 mg/kg for both the whole and filleted trout obtained after 12 and 9 days, respectively, may be proposed as the upper limit for spoilage initiation (freshness indicator) of fresh rainbow trout based on sensorial and microbiological (total viable count of 10(6) to 10(7)) data. With respect to other amines determined, both tyramine and spermine may also be proposed as freshness indicators preferably for whole trout, whereas tryptamine, beta-phenylethylamine, histamine, and cadaverine produced only during later stages of storage are not suitable as freshness indicators of either whole or filleted trout.     

Histamine accumulation and histamine-forming bacteria in Indian anchovy (Stolephorus indicus)

Accumulation of histamine, trimethylamine (TMA), and total volatile base nitrogen (TVB-N), as well as microbial population incidence in Indian anchovy (Stolephorus indicus) during storage in ice and at 15 and 35 °C were investigated. Histamine was as low as 1.9 mg/100 g in 15 days at ice storage, but it increased to 19.0 mg/100 g after 32 h at 15 °C. Histamine rapidly increased to 25.4 mg/100 g when stored at 35 °C for 8 h. TVB-N and TMA began to sharply increase after 11 days in ice storage, but abruptly increased after 16 and 8 h of storage at 15 and 35 °C, respectively. A high number of Enterobacteriaceae (10¹⁰–10¹¹ cfu/g) was detected and shown to be the dominant group of microbial flora during spoilage of Indian anchovy at both 15 and 35 °C. A total of 153 bacterial strains were selected from the prescreening step using various selective media. Only 75.8% of these selected isolates showed a positive reaction in Niven's differential medium, and 27.6% of the positive isolates were true histamine formers when confirmed by the enzymatic method. Prolific histamine formers were identified as Morganella morganii, Proteus vulgaris, and Enterobacter aerogenes, and produced high histamine content of 104.1–203.0 mg/100 ml. Optimum growth and histamine production of selected strains of these three species was at 35 °C in histamine evaluation broth (HEB) containing 0.5% NaCl, pH 5. E. aerogenes produced the highest histamine of 500 mg/100 ml at the optimum condition. All studied strains did not produce histamine at ⩾10% NaCl.     

Preservation of salted,vacuum-packaged,refrigerated sea bream (Sparus aurata) fillets by irradiation: microbiological,chemical and sensory attributes

The effect of gamma irradiation (1 and 3 kGy) on the shelf-life of salted, vacuum-packaged sea bream (Sparus aurata) fillets stored under refrigeration was studied by monitoring the microbiological, chemical and organoleptic changes occurring in fish samples. Non-irradiated, salted, vacuum-packaged fish served as control samples. Irradiation affected populations of bacteria, namely, Pseudomonas spp., H₂S-producing bacteria, Brochothrix thermosphacta, Enterobacteriaceae and lactic acid bacteria. The effect was more pronounced at the higher dose (3 kGy) applied. Of the chemical indicators of spoilage, trimethylamine (TMA) values of non-irradiated, salted sea bream increased slowly to 8.87 mg N (100 g)⁻¹ flesh (whereas for irradiated, salted samples significantly lower values were obtained, reaching a final TMA value of 6.17 and 4.52 mg N (100 g)⁻¹ flesh at 1 and 3 kGy, respectively (day 42). Total volatile base nitrogen values increased slowly attaining a value of 60.52 mg N (100 g)⁻¹ for non-irradiated, salted sea bream during refrigerated storage whereas for irradiated fish, lower values of 48.13 and 37.21 mg N (100 g)⁻¹ muscle were recorded at 1 and 3 kGy, respectively (day 42). Thiobarbituric acid values for irradiated, salted sea bream samples were higher than respective non-irradiated (salted) fish, and increased slowly until day 28 of storage reaching final values of 1.01 (non-irradiated, salted), 2.15 (1 kGy) and 3.26 mg malonaldehyde kg⁻¹ flesh (3 kGy), respectively (day 42). Sensory evaluation (taste) showed a reasonably good correlation with bacterial populations. On the basis of sensorial evaluation, a shelf-life of 27–28 days was obtained for vacuum-packaged, salted sea bream irradiated at 1 or 3 kGy, compared to a shelf-life of 14–15 days for the non-irradiated, salted sample.     

An exploratory study of sensory attributes and consumer traits underlying liking for and perceptions of freshness for ready to eat mixed salad leaves in Italy

The role of sensory attributes and storage time information in driving liking for and perceptions of freshness for ready to eat vegetables was investigated in mixed salad leaves for different storage times (0, 3, 7 and 9 days). A modified Repertory Grid Method was used to identify ten attributes describing consumer's perception of sensory properties over storage. Eighty-one consumers rated the overall liking, the intensity of sensory attributes and the level of freshness in salad samples at different storage times. Freshness was evaluated in blind and informed conditions. Furthermore, consumers filled in a Food Choice Questionnaire and rated the importance of six attributes known to be important for ready to eat salad choice. The relationships between sensory properties significantly affected by storage time, perceived freshness and liking showed that both liking and freshness were positively related to appearance attributes (green colour, salad assortment and leaf turgidity). The perceived level of freshness, expiry date and appearance were confirmed as the most important attributes for ready to eat salad choice. Two clusters of consumers (Cl1: n = 49; Cl2: n = 32) were identified based on the mean liking rating. The positive effects on health and mood as well as ethical concerns drove food choice more in Cl1 than in Cl2 subjects. No significant effect of storage time was found on liking ratings expressed by Cl1 in blind conditions, while a significant decrease of perceived freshness was observed. On the other hand, results from Cl2 in blind conditions showed a significant decrease of both liking and perceived freshness. Information about storage time significantly affected freshness ratings in Cl1 but did not influence those from Cl2.Results suggest that collection of sensory data, affective responses and information about the background of subjects is needed to fully investigate the perceptions of freshness from a consumer perspective.     

Survival of Lactobacillus delbrueckii UFV H2b20 in ice cream produced with different fat levels and after submission to stress acid and bile salts

The survival of Lactobacillus delbrueckii UFV H2b20 in three ice cream formulations (low fat, fat free and high fat) was evaluated after the processing and storage at ?16 °C. The survival of L. delbrueckii UFV H2b20 was not significantly affected (P > 0.05) in three ice cream formulations after processing. The same result was observed during storage for 40 days at ?16 °C. Cells of L. delbrueckii UFV H2b20 incorporated in three ice cream formulation survived when exposed to acid stress and bile salts. The results demonstrate that L. delbrueckii UFV H2b20 has potential for being used in ice cream and capacity to resist acid stress and to grow in the presence of bile salts. This demonstrates that reduction of fat in ice cream does not compromise the viability of L. delbrueckii UFV H2B20.     

Effect of ozone on microbial,chemical and sensory attributes of shucked mussels

The effect of ozonation in aqueous solution (O₃ concentration=1 mg/l, time of ozonation: 60 and 90 min) on the shelf-life of shucked, vacuum-packaged mussels, stored under refrigeration was studied by monitoring the microbiological, chemical and sensory changes occurring in mussel samples, for a period of 12 days. Non-ozonated vacuum-packaged mussels served as the control sample. Ozonation affected populations of bacteria namely, aerobic plate count (APC) (0.7–2.1 log cycle reduction), Pseudomonas spp. (0.5–1.1 log cycle reduction) and H₂S-producing bacteria (1.1–2.5 log cycle reduction), Brochothrix thermosphacta (0.3–1.4 log cycle reduction), lactic acid bacteria (0.3–0.8 log cycle reduction) and Enterobacteriaceae (0.5–1.5 log cycle reduction). The effect of ozonation was more pronounced at the longer time of ozonation. Of the chemical indicators of spoilage monitored, trimethylamine values of all mussel samples remained relatively low throughout the entire storage period, attaining values of 7.5, 6.0 and 6.4 mg N/100 g for the control and ozonated for 60 and 90 min samples, respectively, on day 12 of storage. Total volatile basic nitrogen (TVB-N) values similarly remained relatively low (⩽20 mg N/100 g) until day 6 of storage, and increased to 31.9, 24.2 and 26.9 mg N/100 g mussel meat for the control and ozonated for 60 and 90 min samples, respectively, on day 12 of storage. Initial TBA values were surprisingly high (30–35 mg MA/kg) and decreased to 23.0, 21.7 and 13.3 mg MA/kg mussel meat on day 12 of storage for the control and the ozonated for 60 and 90 min samples, respectively. Sensory evaluation (odor, taste and texture) of cooked mussels showed a good correlation with bacterial populations. On the basis of sensory analyses, a shelf-life of 12 days was obtained for vacuum-packaged mussels ozonated for 90 min as compared to a shelf-life of 9 days for the control sample.     

Effect of salt concentration and temperature of storage water on the physicochemical properties of fish proteins

Biochemical and physical properties of fish proteins from damaged (filleted and skinned) and undamaged (free of trauma or broken skin) Pacific whiting were investigated during chilling in various salt concentrations at 0.7 to ?1.1 °C. The increase of pH and moisture content were suppressed when chilling water contained higher concentration of NaCl. Conductivities of damaged fish were maximal after 24 h storage, but those of undamaged fish continuously increased throughout 72 h. K-values increased, but rapidly increased at lower salt concentrations. Puncture force and deformation were very low when chilled water contained higher concentration of salt (2–3 g/100 ml). Gel colors were also negatively affected as the concentration of salt increased for chilling water. Our study suggest Pacific whiting may be stored at 0–2 °C, but at 0–1 g/100 ml salt concentration.     

Quality assessment of whole and gutted sardines (Sardina pilchardus) stored in ice

The quality and shelf life of whole ungutted and gutted sardines ( Sardina pilchardus ) stored in ice were studied. The changes in the fish were investigated by sensory assessments, chemical analyses and microbiological analyses. The sensory scores of uneviscerated and gutted sardines stored in ice at +4 °C were 7 days. The chemical indicators of spoilage, total volatile basic nitrogen and trimethylamine values of gutted sardine increased very slowly, whereas for whole ungutted samples higher values were obtained reaching a final value of 15.03–29.23 mg per 100 g and 2.36–4.16 mg per 100 g, respectively (day 9). Peroxide and thiobarbituric acid values remained lower for whole ungutted sardine samples until day 9 of storage, whereas for gutted fish were higher. The level of histamine exceeded the legal limit in whole ungutted sardine after 7 days of storage in ice, during which sardines were rejected by the sensory panel. Mesophilic aerobic bacteria count, H₂S-producing bacteria, sulphide reducing anaerobe Clostridias, Enterobacteriaceae count of whole ungutted sardine samples are higher than gutted sardine samples during the storage. Psychrotrophic bacteria counts of the two groups were not different. The limits of microbiological data were not exceeded throughout the storage in both the groups' samples.     

Effect of modified atmosphere packaging,storage period,and storage temperature on the residual nitrate of sliced-pastırma,dry meat product,produced from fresh meat and frozen/thawed meat

The amount of nitrite in sliced-pastirma made, from fresh or frozen (which was stored at −18 °C for 240 days and then thawed at 10 °C for 24 h) M. Longissimus dorsi muscle was determined. Sliced-pastirma samples were stored in modified atmosphere packages (50% N₂ + 50% CO₂) at 4 and 10 °C for 150 days, and the amount of residual nitrite was measured after 0, 30, 60, 90, and 150 days of storage. The residual nitrite of pastirma samples made with frozen/thawed meat was higher than that of the pastirma made from fresh meat at both 0 day and at the end of the storage (150 days). The storage temperature (p < 0.01), storage period (p < 0.01) and the storage period × the storage temperature interaction (p < 0.01) had significant effects on the amount of the residual nitrite.     

Effect of Quillaja saponaria dietary administration on colour,oxidative stability and volatile profile of muscle longissimus dorsi of Barbarine lamb

Eighteen Barbarine lambs were assigned during 77 days to three dietary treatments (n = 6): control, oat hay ad libitum and 400 g of concentrate; QS60 and the QS90 control diet supplemented with 60 mg and 90 mg Quillaja saponaria (QS) bark extract/kg dry matter, respectively. The analysis of pre-frozen longissimus dorsi muscle showed that the QS90 treatment reduced meat redness (a*) and saturation (C*) measured after 2 h of blooming. It also reduced the rate of decrease in a* values (P = 0.02) during 14 days of refrigerated storage. Supplementation with QS extended meat colour stability by reducing (P < 0.05) the rate of increase in hue angle (H*) values. Neither the rate of metmyoglobin accumulation at the meat surface nor lipid peroxidation over storage duration differed between treatments. The overall meat volatile compound profile was similar between the groups. We conclude that supplementing QS affects meat colour development at the meat surface and extends its stability without producing detrimental effects on meat volatile compounds.     

Study of the hard-to-cook property of stored yam tubers (Dioscorea dumetorum) and some determining biochemical factors

In an attempt to investigate the hard-to-cook phenomenon in Dioscorea dumetorum tubers during storage, selected physical and chemical characteristics were monitored. A 3 × 5 factorial experiment with storage conditions (15 °C, 59% RH; 30 °C, 75% RH; 45 °C, 86% RH) and storage period (0, 2, 4, 7 and 14 days) as variables was carried out. Changes in cooked hardness, water absorption, water-holding capacity and solid loss of steeped tubers as well as phytate, total phenols and lignin contents were monitored. Water uptake and solid loss of steeped tubers decreased significantly (P ⩽ 0.05) with storage period, suggesting that storage affects cell wall membrane permeability of the tubers. Cooked hardness analyses indicated significant difference (P ⩽ 0.05) between fresh and stored tubers and its rate varied with storage time and storage conditions. Cooked hardness values correlated negatively (r = −0.922–0.857, P ⩽ 0.05, d.f. = 146) with phytate and total phenols. A multiple mechanism for D. dumetorum tubers hardening is presented which includes phytate loss as a minimal contributor to cooked hardness during the first days of storage and total phenol loss via a lignification-like mechanism as a major contributor.     

Conventional freezing plus high pressure–low temperature treatment: Physical properties,microbial quality and storage stability of beef meat

Meat high-hydrostatic pressure treatment causes severe decolouration, preventing its commercialisation due to consumer rejection. Novel procedures involving product freezing plus low-temperature pressure processing are here investigated. Room temperature (20 °C) pressurisation (650 MPa/10 min) and air blast freezing (−30 °C) are compared to air blast freezing plus high pressure at subzero temperature (−35 °C) in terms of drip loss, expressible moisture, shear force, colour, microbial quality and storage stability of fresh and salt-added beef samples (Longissimus dorsi muscle). The latter treatment induced solid water transitions among ice phases. Fresh beef high pressure treatment (650 MPa/20 °C/10 min) increased significantly expressible moisture while it decreased in pressurised (650 MPa/−35 °C/10 min) frozen beef. Salt addition reduced high pressure-induced water loss. Treatments studied did not change fresh or salt-added samples shear force. Frozen beef pressurised at low temperature showed L, a and b values after thawing close to fresh samples. However, these samples in frozen state, presented chromatic parameters similar to unfrozen beef pressurised at room temperature. Apparently, freezing protects meat against pressure colour deterioration, fresh colour being recovered after thawing. High pressure processing (20 °C or −35 °C) was very effective reducing aerobic total (2-log₁₀ cycles) and lactic acid bacteria counts (2.4-log₁₀ cycles), in fresh and salt-added samples. Frozen + pressurised beef stored at −18 °C during 45 days recovered its original colour after thawing, similarly to just-treated samples while their counts remain below detection limits during storage.     

Development of probiotic beads similar to fish eggs

Probiotic foods are mainly restricted to dairy and soy products. This study aimed to develop a new probiotic beads similar to fish eggs, commonly used in oriental cuisine. Beads were produced by the extrusion encapsulation technique with calcium alginate, added to one of the following cultures: Lactobacillus rhamnosus GG ATCC 53103 and Bifidobacterium animalis DN-173 010 and stored for 30 days at 4 °C. The beads were characterized by the size, weight, morphology and viability of the probiotic strains in different storage temperatures and in simulated gastric juice adjusted to different pH values. The beads were also evaluated by a sensorial affective hedonic scale. The beads present a 2.8 mm diameter and a weight of 0.01 g (p > 0.05). Free and encapsulated cells were tolerant to pH 3.0. At pH 2.5 only of the encapsulated cells presented counts above 6 Log colony-forming units per gram (CFU/g). Beads containing L. rhamnosus showed higher viability 10⁷ CFU/g in storage for 30 days under refrigeration. The beads may be stored at abusive temperature for 5 h without loss of viability cells. The probiotic product developed showed an 82.2% acceptability index of overall characteristics and good market potential as a new probiotic product.     

Technological,rheological and sensory characterizations of a yogurt containing an exopolysaccharide extract from Lactobacillus fermentum Lf2, a new food additive

Lactobacillus fermentum Lf2, an autochthonous strain isolated as a non starter culture in Cremoso cheese, produces high EPS levels (~ 1 g/L) in optimized conditions (SDM broth, pH 6.0, 30 °C, 72 h). Technological (texture profile and rheological analysis) and sensory properties of non-fat yogurts with 300 and 600 mg EPS/L were studied at 3 and 25 days after manufacture. Yogurts with different EPS concentrations showed higher hardness values than the control group at both periods of time, being the only significant difference that remained stable during time. The consistency index was also higher for the treated samples at both times evaluated, being significantly different for samples with 300 mg/L of EPS extract, while the flow behavior index was lower for EPS-added yogurts. The thixotropic index was lower (P < 0.05) for samples with the highest EPS extract concentration at the end of the storage time. Regarding the sensory analysis, those yogurts with 600 mg/L of EPS extract presented the highest values of consistency at 3 days of storage. No considerable differences for defects (milk powder, acid, bitter and cooked milk flavors) were perceived between treated and control samples at both times evaluated. Syneresis was also studied and samples with 600 mg/L of EPS extract presented the lowest syneresis values at 25 days of storage, which considerably decreased with the time of storage.In conclusion, the EPS from L. fermentum Lf2, used as an additive, provided yogurt with creamy consistency and increased hardness, without the presence of unwanted defects and improving the water holding capacity of the product. All the analysis done showed the potential of this extract to be used as a technofunctional natural ingredient, and it should be considered its positive impact on health, according to previous studies.     

High pressure treatments on the inactivation of Salmonella Enteritidis and the characteristics of beef carpaccio

The effect of high pressure (HP) on Salmonella enterica subsp. enterica serovar Enteritidis in beef carpaccio stored under temperature abuse conditions (8 °C) during 30 days was investigated. After treatment, reductions of S. Enteritidis were 3.68 and 5.94 log cfu/g in samples pressurized at 450 MPa for 5 and 10 min, respectively, whereas the pathogen was only detected after enrichment of samples treated at 450 MPa for 15 min. During storage, counts of S. Enteritidis decreased 0.26 log cfu/g in non-pressurized carpaccio, 1.33 log cfu/g in carpaccio treated at 450 MPa for 5 min and were only detected after enrichment in carpaccio pressurized at 450 MPa for 10 or 15 min. Color (L*, a* and b*) varied with pressurization and storage, with higher changes in carpaccio treated at longer pressurization times. Shear resistance was slightly lower in treated samples just after pressurization, but increased at the end of the storage period. Maximum force was less affected by treatment.     

Evaluation of the microbiological safety and sensory quality of rainbow trout (Oncorhynchus mykiss) processed by the sous vide method

This work evaluates the microbiological quality and sensorial characteristics of rainbow trout processed by the sous vide method under different time/temperature conditions and stored at 2°C and 10°C.The equivalent heat treatments applied in core were: 3.3 min at 90°C (PV₇₀ in core 331.64), 1.04 min at 90°C (PV₇₀ in core 104.5) and 5.18 min at 70°C (PV₇₀ in core 5.18). The product stored at 2°C or 10°C was periodically evaluated to investigate its sensory quality, microbiological condition and proximate composition. The batches stored at 2°C had lower growth counts of mesophiles and psychrotrophs. Moreover, these counts decreased by increasing the heating temperature and time. Staphylococcus aureus, Bacillus cereus, Clostridium perfringens and Listeria monocytogenes were not found in any of the samples. Neither aerobic nor anaerobic spores were detected in the trout samples processed at 90°C for 3.3 min in core and stored at 2°C after 45 days. A heat treatment of 90°C for 3.3 min in core was the most effective to extend the shelf-life of trout (>45 days).Therefore, it can be concluded that the treatment at 90°C for 3.3 min in core is the most effective to ensure the safety and extend the shelf-life of sous vide trout preserving its sensory characteristics.This study establishes the microbiological quality of sous vide trout and emphasizes the relevance of the microbiological quality of the raw materials, heat treatment and storage temperature to ensure the safety of the product, since this fatty fish is not eviscerated and high counts can be found in the raw fish.