Effect of carbon monoxide packaging and lactate enhancement on the color stability of beef steaks stored at 1°C for 9 days

Our objective was to assess the effects of lactate enhancement in combination with different packaging systems on beef longissimus lumborum and psoas major steak color. Strip loins and tenderloins (n = 16) were assigned to one of four injection treatments (non-injected control, water-injected control, 1.25%, and 2.5% lactate in the finished product). Steaks were individually packaged in either vacuum, high-oxygen (80% O₂/20% CO₂), or 0.4% CO (30% CO₂/69.6% N₂) and stored for either 0, 5, or 9 days at 1 °C. The L^∗ and a^∗ values of both the longissimus and psoas responded similarly to lactate, which at 2.5% darkened steaks (P < 0.05) packaged in all atmospheres and improved (P < 0.05) the redness of steaks packaged in high-oxygen. Packaging steaks in CO did not counteract the darkening effects of lactate. Nevertheless, CO improved (P < 0.05) color stability compared with high-oxygen packaging.     

Effects of ozonation on microbiological,chemical and sensory attributes of vacuum-packaged rainbow trout stored at 4±0.5°C

The effects of ozone in aqueous solution on the shelf life of whole, vacuum-packaged rainbow trout, stored under refrigeration (4±0.5°C) were studied by monitoring the microbiological, chemical and sensory changes for a period of 15 days. Vacuum-packaged non-ozonated trout served as the control sample. Ozonation affected populations of bacteria namely, mesophilic aerobic bacteria, Pseudomonas spp. and H₂S-producing bacteria until day 11 of storage, Brochothrix thermosphacta, lactic acid bacteria and Enterobacteriaceae until day 8 of storage. Trimethylamine (TMA) values of all rainbow trout samples remained low (<3 mg N/100 g) until day 11 of storage, and then increased to 12.2, 8.9 and 4.7 mg N/100 g for the control and the samples ozonated for 60 and 90 min, respectively on day 15 of storage. Total volatile basic nitrogen (TVB-N) values remained relatively constant (20–25 mg N/100 g) until day 11 of storage, but increased to 61.1, 37.6 and 39.4 mg N/100 g flesh for the control and ozonated specimen for 60 and 90 min, respectively on day 15 of storage. Thiobarbituric acid (TBA) values remained relatively constant (1–3 mg MA/kg flesh) until day 12 of storage but increased to 8.4, 6.4 and 3.8 mg MA/kg flesh on day 15 of storage for the control and the ozonated trout for 60 and 90 min, respectively. Sensory evaluation (odor, taste and texture) of cooked rainbow trout showed a very good correlation with bacterial populations. On the basis of both sensory and microbiological data, a shelf life of 10 and 12 days was obtained for ozonated, vacuum-packaged and refrigerated rainbow trout at 60 and 90 min, respectively.     

Development and validation of a predictive microbiology model for survival and growth of Salmonella on chicken stored at 4 to 12 °C

Salmonella spp. are a leading cause of foodborne illness. Mathematical models that predict Salmonella survival and growth on food from a low initial dose, in response to storage and handling conditions, are valuable tools for helping assess and manage this public health risk. The objective of this study was to develop and to validate the first predictive microbiology model for survival and growth of a low initial dose of Salmonella on chicken during refrigerated storage. Chicken skin was inoculated with a low initial dose (0.9 log) of a multiple antibiotic-resistant strain of Salmonella Typhimurium DT104 (ATCC 700408) and then stored at 4 to 12 °C for 0 to 10 days. A general regression neural network (GRNN) model that predicted log change of Salmonella Typhimurium DT104 as a function of time and temperature was developed. Percentage of residuals in an acceptable prediction zone, from -1 (fail-safe) to 0.5 (fail-dangerous) log, was used to validate the GRNN model by using a criterion of 70% acceptable predictions. Survival but not growth of Salmonella Typhimurium DT104 was observed at 4 to 8 °C. Maximum growth of Salmonella Typhimurium DT104 during 10 days of storage was 0.7 log at 9 °C, 1.1 log at 10 °C, 1.8 log at 11 °C, and 2.9 log at 12 °C. Performance of the GRNN model for predicting dependent data (n=163) was 85% acceptable predictions, for predicting independent data for interpolation (n=77) was 84% acceptable predictions, and for predicting independent data for extrapolation (n=70) to Salmonella Kentucky was 87% acceptable predictions. Thus, the GRNN model provided valid predictions for survival and growth of Salmonella on chicken during refrigerated storage, and therefore the model can be used with confidence to help assess and manage this public health risk.     

Effect of packaging atmosphere and pH on the virulence and growth ofYersinia enterocoliticaon pork stored at 4°C

Growth and virulence of pathogenicYersinia enterocoliticawere investigated on high (pH>6.0) and normal (pH<5.8) pH pork packaged in modified atmospheres and stored at 4°C. Modified atmospheres used in the study were vacuum packaging and saturated CO₂. Pork was packaged in a high gas barrier packaging film and examined over a 30-day period. Phenotypic characteristics were used to detect the presence of the virulence plasmid ofY. enterocoliticaafter exposure to the pork packaging and storage regimen. Phenotypic characteristics ofY. enterocoliticaisolates from pork loin stored at 4°C for 30 days that were studied included Congo red uptake, calcium dependence and autoagglutination in methyl red Voges–Proskauer broth and tissue culture medium. Numbers ofY. enterocoliticaon the lean surface of high pH pork slices increased approximately 2.7logcfucm⁻²when vacuum packaged and stored at 4°C for 30 days. Storage of inoculated normal pH pork in 100% CO₂resulted inY. enterocoliticaremaining in the lag phase over the storage period. Virulence ofY. enterocoliticawas maintained in 25 to 35% of isolates following storage for 30 days at 4°C in vacuum- and CO₂-packaged meats and was not affected by pH of the pork loin.     

Effects of combining of smoking and marinating on the shelf life of anchovy stored at 4°C

The quality of smoked and marinated anchovy was investigated in terms of sensory, chemical [total volatile basic nitrogen (TVB-N), thiobarbituric acid (TBA), peroxide value (PV), fatty acids, free fatty acids (FFA), and pH] and microbiological parameters (total aerobic count (TVC), coliform, Escherichia coli, Salmonella, Staphylococcus aureus) during 7 months of storage. The results of sensory analyses showed that the total appearance, odor-taste, and texture scores decreased gradually during storage period. The results of the chemical analyses also correlated well with the sensory analyses apart from TVBN value. TBA significantly increased (p<0.05) from 1.9 to 4.25 MA/kg after the storage of 6 month. Peroxide value (POV) showed significant fluctuations (p<0.05) during the storage period. Initial TVC of 3.8 log CFU/g increased to 6.2 log CFU/g at the end of storage period. According to results obtained from sensory, chemical, and microbiological analyses, shelf life of this product was about 6 month.     

Effect of oat's soluble fibre (β-glucan) as a fat replacer on physical, chemical, microbiological and sensory properties of low-fat beef patties

This study evaluated the effect of adding oat fibre source of β-glucan (13.45%) on physical, chemical, microbiological and sensory traits of low-fat (<10%) beef patties as compared to 20% fat control patties. Significant (p<0.05) improvements in cooking yield (74.19%), and retentions of fat (79.74%) and moisture (48.41%) of low-fat patties were attributed to the water binding ability of β-glucan. Because of larger water retentions moisture contents of raw and cooked low-fat patties were higher (p<0.05) than those of the control patties. Cholesterol content was similar across formulations. Low-fat and control beef patties remained stable in microbiological quality during 60days frozen storage. Low-fat patties were found to be of lower degree of likeness in the taste but juicer than control (p<0.05). Besides appearance, tenderness and colour were not affected by the addition of oat's soluble fibre. Oat fibre can be used successfully as a fat substitute in low-fat beef patties.     

Effects of turmeric, shallot extracts, and their combination on quality characteristics of vacuum-packaged rainbow trout stored at 4 ± 1 °C

The effects of turmeric extract (T), shallot extract (Sh), and their combination (T + Sh) on the quality of vacuum-packaged rainbow trout (Oncorhynchus mykiss) were examined during refrigerated storage (4 ± 1 °C) over a period of 20 d. Fish samples were divided into 4 batches; 3 batches were treated by dipping for 30 min in aqueous solution of turmeric extract (1.5%; v/v), shallot extract (1.5%; v/v), or turmeric and shallot extract combination (1.5%+ 1.5% v/v), while the fourth batch was dipped in distilled water as a control sample. The control and the treated fish samples were analyzed periodically for microbiological (total viable count, psychrotrophic count), chemical (total volatile base nitrogen [TVB-N], peroxide value [PV], and thiobarbituric acid [TBA] value), and sensory characteristics. The results indicated that the effect of the T, Sh, and T + Sh on the fish samples were to enable the good quality characteristics to be retained longer and to extend the shelf life during the refrigerated storage.     

Changes of microbial diversity and volatile compounds in edible and deteriorated Qingke barley fresh noodles stored at 25 °C

Microbial diversity and volatile compounds in Qingke barley fresh noodles (QBFN) with different storage time at 25 ± 1 °C were investigated. The results showed that Pseudomonas, Pantoea, Erwinia and Alternaria, Pyrenophora, Penicillium were the dominant microorganisms in edible QBFN (stored for 0 and 12 h), while Pantoea, Erwinia, Bacillus and Penicillium, Aspergillus were the dominant spoilage microorganisms in deteriorated QBFN (stored for 18 h). The edible QBFN have high concentration of aldehydes (61.27 μg kg⁻¹), furan and pyrazines (60.87 μg kg⁻¹), alcohols (49.74 μg kg⁻¹) and ketones (29.74 μg kg⁻¹) that give basic flavours to the QBFN. As storage time increased, the concentrations of above volatile compounds decreased, and new esters and sulphuric compounds which gave unpleasant odours to the QBFN appeared. Multivariate data analysis methods showed that 2-pentyl-furan, hexanal, 5-Ethylcyclopent-1-enecarboxaldehy, cyclohexanol and methyl allyl sulphide, ethyl isovalerate were the main volatile compounds that make a difference in flavour between the edible and deteriorated QBFN.     

Influence of storage period and packaging method on sliced dry cured beef “Cecina de Leon”: Effects on microbiological,physicochemical and sensory quality

Quality aspects of sliced dry-cured beef “Cecina de León” preserved in vacuum and gas mixtures (20%/80% CO₂/N₂ and 80%/20% CO₂/N₂) were studied. The evolution of microbiological, physicochemical and sensory parameters were analysed during storage (210 days) at 6 °C. Although microbial counts at 60 days of the gas-packaged samples were lower than the vacuum-packed ones, they were never higher than the spoilage limit (7 log ufc/g). A slight increase (p < 0.05) in pH was observed throughout storage of “Cecina de León” packaged under vacuum and in gas mixtures. However, a decrease (p < 0.05) in a_w was observed during storage of “Cecina de León” packaged under vacuum but a_w did not vary (p > 0.05) during storage in the gas-packaged samples. No changes were observed (p > 0.05) in lightness (L¹), redness (a¹) and yellowness (b¹) in vacuum and gas packaged samples during storage. However, sensorially evaluated colour showed lower values in gas packaged samples during 30 days storage. This difference was decisive in establishing the shelf-life of “Cecina de León” slices preserved in gas mixtures (20%/80% CO₂/N₂ and 80%/20% CO₂/N₂). Therefore, from a microbiological point of view, gas mixtures are more effective in extending the shelf-life of “Cecina de León” slices. It is concluded that vacuum packaging allows longer storage than gas-packaging as it maintains a good visual appearance of “Cecina de León”, the main parameter in consumers’ perception of meat quality.     

Effects of aluminium foil and cling film on biogenic amines and nucleotide degradation products in gutted sea bream stored at 2±1 °C

Biogenic amines and nucleotide degradation products of sea bream stored in ice, wrapped in aluminium foil (WAF) and in cling film (WCF) at 2±1 °C were investigated by using a rapid HPLC method. Results obtained from this study showed that for household purposes packing fish in different materials has a little effect on the biogenic amines formation and nucleotide degradation products. The highest decrease of IMP content was observed for sea bream in WAF, followed by WCF. INO values showed a fluctuation and remained below the levels of 5.5 μmol/g for all storage conditions. Hx value constantly increased with the storage time during chilled storage. For all of the storage condition, K and Ki value increased linearly with storage time. At the end of the storage period, K, Ki, H and G value reached 60–76%, 65–81%, 30–54% and 89–173%, respectively. Among biogenic amines, (trimetylamine) TMA, putrescine, cadaverine, spermidine, spermine, tryptamine, tyramine, β-phenylalanine and histamine were detected during storage period. TMA and putrescine were observed to increase linearly during storage period. Histamine production was only found at the end of storage period. The highest histamine values for fish wrapped in aluminium foil were 6.4 mg/100 g and fish wrapped in cling film was 4.6 mg/100 g.     

Effects of nisin, EDTA and salts of organic acids on Listeria monocytogenes, Salmonella and native microflora on fresh vacuum packaged shrimps stored at 4 °C

Nisin (500 IU ml⁻¹), EDTA (0.02 M), potassium sorbate (PS) (3%, w/v), sodium benzoate (SB) (3%, w/v) or sodium diacetate (SD) (3%, w/v); alone or in combination were used to dip uninoculated shrimps and shrimps inoculated with Listeria monocytogenes or Salmonella (∼4.0–5.0 log CFU g⁻¹). Shrimps were then drip-dried, vacuum packaged and stored at 4 °C for 7 days. Untreated shrimps were used as a control. Numbers of L. monocytogenes, Salmonella and native background microflora were determined on uninoculated and inoculated shrimps on days 0, 3 and 7. Nisin–EDTA–PS and nisin–EDTA–SD significantly reduced (p < 0.05) L. monocytogenes numbers by 1.07–1.27 and 1.32–1.36 log CFU g⁻¹, respectively, on day 0 and 3. However, all treatments failed to significantly reduce (p > 0.05) Salmonella counts on shrimps throughout storage. On day 7, numbers of aerobic bacteria, psychrotrophic bacteria and Pseudomonas on combined nisin–EDTA–salt of organic acids treated shrimps were significantly lower (p < 0.05) by 4.40–4.60, 3.50–4.01, and 3.84–3.99 log CFU g⁻¹ respectively, as compared to the control. Dipping in organic acids solutions followed by vacuum packaging and chilled storage can help reduce L. monocytogenes and native microflora, but not Salmonella, on fresh shrimps.     

Changes in quality of rainbow trout (Oncorhynchus mykiss) fillets preserved with salt and sugar at low concentrations and stored at 4°C

The effects of dry-curing with low concentrations of salt and sugar on the quality of rainbow trout (Oncorhynchus mykiss) fillets were studied over a 16-day storage period at 4°C. Physicochemical characteristics (total volatile base nitrogen (TVB-N), biogenic amines (BAs), ATP-related compounds and K value), microbial populations (total aerobic counts (TAC), H₂S-producing bacteria, Pseudomonas, Aeromonas, and lactic acid bacteria) and sensory (SA) indicators were analyzed. Fish samples were subjected to the following treatments: untreated (control), dry-cured with 1.3% salt (T1), and dry-cured with 1.3% salt that also contained 0.9% sugar (T2). SA indicated that the sensory quality of the control, T1, and T2 was unacceptable after 8, 12, and 12 days of storage, respectively. Moreover, the cadaverine concentration of treated samples was significantly lower (P < 0.05) than the control after storing for 8 days. T1 and T2 were significantly higher (P < 0.05) than the control in inosine 5-monophosphate (IMP) content from the 2th to 10th day. Cadaverine, putrescine, hypoxanthine, and TAC were correlated significantly (P < 0.01) with SA, and these seemed to be reliable indicators of fish quality. The results indicated that curing treatments extended the shelf life of rainbow trout fillets, which could be exploited by processors.     

Physicochemical,microbiological, and sensory attributes of chitosan-coated grass carp (Ctenopharyngodon idellus) fillets stored at 4°C

This study investigated the effect of chitosan coating (1 and 2%) on the quality of grass carp fillets stored at 4°C for 20 days. During storage, the physicochemical properties (pH, thiobarbituric acid value, total volatile basic nitrogen value, trimethylamine nitrogen value, K-value, water loss, and instrumental texture), microbiology (total viable count and psychrotrophic count), and sensory properties were evaluated. The results showed that chitosan coating could effectively inhibit bacterial growth, improve physicochemical and sensory qualities, and it reduced the deterioration of the quality of grass carp fillets. Compared with fillets without chitosan coating, the shelf life of fillets with 1 and 2% chitosan coating was extended by ~3 and 6–7 days, respectively.     

The combined effect of squid pen chitooligosaccharides and high voltage cold atmospheric plasma on the shelf-life extension of Asian sea bass slices stored at 4 °C

Combined effects of high voltage cold atmospheric plasma (HV-CAP) generated with the mixture of argon and oxygen (90%Ar/10%O₂) for 5 min and chitooligosaccharide (COS) from squid (Loligo formosana) pen (internalized shell) at different concentrations (0.05, 0.1 and 0.2 g/100 g fish slices) on the shelf-life of Asian sea bass (ASB) slices were investigated during storage at 4 °C for 18 days. Total viable count (TVC) of fish slices treated with 0.1 or 0.2 g/100 g COS in conjunction with HV-CAP was lower than the acceptable limit (log 10⁶ CFU/g sample) within 18 days. The growth of various pathogenic and spoilage bacteria including psychrophilic bacteria, Clostridium perfringens (not detected), lactic acid bacteria (3.77–4.37 log CFU/g), Enterobacteriaceae (4.03–4.50 log CFU/g), Pseudomonas (6.62–6.82 log CFU/g) and hydrogen sulphide (H₂S)-producing (4.04–5.05 log CFU/g) bacteria of HV-CAP-treated slices containing COS was more inhibited than other treatments, especially during the first 15 days of storage. The thiobarbituric acid reactive substances (TBARS) and peroxide values (PV) of slices treated with combined HV-CAP and COS (0.1 or 0.2 g/100 g) were reduced by 28‐–64 and 40–46%, respectively than those treated with only HV-CAP throughout the storage (p <.05). Similarly, for HV-CAP treated slices, addition of COS decreased the total carbonyl content by 15–24% than those added without COS. COS was able to lower the oxidation of polyunsaturated fatty acids of slices caused by HV-CAP. Therefore, HV-CAP together with COS effectively prolonged the shelf-life of ASB slices with sensory acceptability at 4 °C for at least 12 days.     

The effects of nanoemulsions based on citrus essential oils on the formation of biogenic amines in trout fillets stored at 4 ± 2°C

The influences of nanoemulsions based on citrus peel (orange, lemon, mandarin, and grapefruit) essential oils on the biogenic amine (BA) formation in rainbow trout (Oncorhynchus mykiss) fillets stored 4 ± 2°C were investigated. The results demonstrated that main BAs in the trout fillets were putrescine, cadaverine, spermidine, spermine, serotonin, tyramine, dopamine, and agmatine. It was determined that nanoemulsion application had generally suppressive effect on the formation of BAs during storage. It was also found that especially orange and lemon nanoemulsion groups were effective on histamine formation. Histamine values ranged from 0.00 to 4.08 in all groups during storage and the levels were below the limit values of FDA and EU throughout the storage period for all treatment groups. Similarly, Quality Index (QI) values of BAs were found to be below legal limits in all groups. Consequently, it was found that nanoemulsions prepared from essential oils kept the BA formation at a lower level during storage.     

Activity of smoke wood condensates against Aeromonas hydrophila and Listeria monocytogenes in vacuum-packaged,cold-smoked rainbow trout stored at 4 °C

The antimicrobial effect of four smoke wood condensates against the psychrotrophic pathogensListeria monocytogenes and Aeromonas hydrophila was tested in vacuum-packed cold-smoked rainbow trout (Oncorhynchus mykiss) stored at refrigeration temperature. Salted trout samples were surface inoculated with L. monocytogenes or A. hydrophila, cold smoked, vacuum packaged and stored at 4 °C for 21 days. At different times of storage, samples were taken and analysed for L. monocytogenes and A. hydrophila by quantitative and qualitative procedures. All smoke extracts showed activity against A. hydrophila. However, only smoke extracts L1 and L2 were effective against L. monocytogenes. Although these extracts caused a reduction in viable cell counts of L. monocytogenes below the detectable level by surface plating procedure, this organism was detected by qualitative analysis in most of the samples. Finally, extracts L1 and L2 also reduced total viable cell counts to undetectable levels.