Ultrasound-Assisted Nanoemulsion Loaded with Optimized Antibacterial Essential Oil Blend: A New Approach against Escherichia coli, Staphylococcus aureus, and Salmonella Enteritidis in Trout (Oncorhynchus mykiss) Fillets.

This study aimed to obtain and characterize an oil-in-water nanoemulsion (NE) loaded with an in vitro optimized bactericidal essential oil blend of 50% oregano, 40% thyme, and 10% lemongrass and to evaluate its potential at three different concentrations (0.5%, 1%, and 2%) in the inactivation of Escherichia coli, Staphylococcus aureus, and Salmonella enterica serotype Enteritidis inoculated in rainbow trout fillets stored at 4 °C for 9 days. Regarding the NE, the nanometric size (<100 nm) with low polydispersion (0.17 ± 0.02) was successfully obtained through ultrasound at 2.09 W/cm2. Considering the three concentrations used, S. Enteritidis was the most susceptible. On the other hand, comparing the concentrations used, the NE at 2% showed better activity, reducing S. Enteritidis, E. coli, and S. aureus by 0.33, 0.20, and 0.73 log CFU/g, respectively, in the trout fillets. Thus, this data indicates that this is a promising eco-friendly alternative to produce safe fish for consumption and reduce public health risks.

Oil-in-water emulsion loaded with optimized antioxidant blend improved the shelf-life of trout (Oncorhynchus mykiss) fillets: a study with simplex-centroid design.

This study aimed to obtain optimized mixture with three essential oils (EOs) for maximum antioxidant activity through the augmented simplex-centroid mixture design and evaluate the effect of this optimized blend on total aerobic psychrotrophic count (TAPC), lipid and protein oxidation, instrumental color parameters and texture profile in rainbow trout fillets at refrigerated storage for nine days. Considering the DPPH and FRAP assays, the ideal EO blend was 66% lemongrass and 34% oregano. During refrigerated storage, this blend at 2000 ppm was equally effective as BHT (100 ppm) (p > 0.05), mitigating the discoloration (a* and b*), lipid, and protein oxidation in 38.83%, 12.95%, 76.13%, and 35.13%, respectively, besides shows greater effectiveness for preserving texture changes (p < 0.05) and extending the shelf life in 13 h. The lemongrass + oregano EO blend reveals a promising natural alternative to enhance the quality of rainbow trout fillets under refrigerated storage. Furthermore, the multiresponse optimization showed to be a strong ally in enabling the use of these EOs by food industries.

Optimizing UVC-LED application to improve the shelf life of vacuum-packed refrigerated stored Nile tilapia (Oreochromis niloticus) fillets.

Although ultraviolet-C light-emitting diode (UVC-LED) has proven antimicrobial effectiveness doses needed to reach it cause adverse effects on the physicochemical quality of fish, and thus, optimization studies are crucial to boost its industrial application. This study aimed to identify optimal UVC-LED conditions for maximum shelf life extension with the least possible quality changes of refrigerated stored tilapia fillets from a central composite rotatable design (CCRD). UVC-LED powers (1, 1.38, and 1.58 mW/cm2 ) and times (500, 1800, and 2700 s) were set on the CCRD, which generated 11 treatments, including three replicate experiments. Treatments were analyzed for total aerobic psychrotrophic count, lipid oxidation, instrumental color, and texture parameters on days 0, 2, 4, 7, 11, and 14. The UVC-LED affected shelf life and physicochemical parameters in a nonlinear fashion. UVC-LED-treated fish had increased shelf life by 2.80-4.76 days and increase or decrease in lipid oxidation (0.025-0.276 mg of malondialdehyde [MDA]/kg), total color change (∆E = 3.47-9.06), and hardness (1.31-8.51 N) over the refrigerated storage depending on specific UVC-LED conditions applied. The optimal UVC-LED condition was 0.97 mW/cm2 with 2503.6 s (2428.50 mJ/cm2 ), which increased the fillet's shelf life by 2.5-fold (2 days) while maintaining quality closer to the original throughout refrigerated storage, resulting in ∆E < 5, an increase of only 0.05 mg of MDA/kg, and preservation of the decrease in hardness by 3.38 N compared to its control counterparts. Therefore, it represents an eco-friendly technology that can easily scaled industrially to enhance the sustainable fish production chain. PRACTICAL APPLICATION: The high fish perishability is a global concern due to food safety risks and waste generation impacting the environment adversely, especially nowadays, where fish production and consumption have increased, and there are more evident efforts to sustainable production. UVC-LED is an eco-friendly technology with proven antimicrobial effectiveness but doses needed to reach this effect enhance oxidative degradation. Despite that, optimization studies concerning the maximum shelf life extension while retaining the physicochemical quality of refrigerated stored fish are a gap in the literature and a barrier to its industrial application. Our findings are helpful in sustainably enhancing the fish production chain.

Can Extraintestinal Pathogenic Escherichia coli with Heat Resistance Profile Overcome Nonthermal Technologies?

Ultraviolet-C light-emitting diode (UVC-LED) and ultrasound (US) are two nonthermal technologies with the potential to destroy pathogens. However, little is known about their effectiveness in strains with a history of heat resistance. Thus, this study aimed to evaluate the phenotype and genotype of heat-resistant extraintestinal pathogenic Escherichia coli (ExPEC) with heat resistance genes after the application of US, UVC-LED, and UVC-LED+US. For this, two central composite rotatable designs were used to optimize the UVC-LED and US conditions in four ExPEC isolated from beef. From the genome of these isolates obtained in a previous study, possible genes for UVC resistance were analyzed. Results showed that US was ineffective in reducing >0.30 log colony-forming unit/mL, and that when used after UVC-LED, it showed a nonsynergic or antagonistic effect. Also, UVC-LED had the greatest effect at the maximum dose (4950 mJ/cm2 from 1.65 mW/cm2 for 50 min). However, the strains showed some recovery after that, which could be implicated in the expression of genes included in SOS system genes, some others present in the transmissible Locus of Stress Tolerance (trxBC and degP), and others (terC). Thus, ExPEC can overcome the conditions used in this study for US, UVC-LED, and UVC-LED+US, probably due to the history of resistance to other cellular damage. The result of this study will contribute to future studies that aim to find better treatment conditions for each food product.

Physicochemical and protein profile of goat whey powder / Perfil físico-químico e proteico do soro de leite de cabra

The cheese after processing, generates whey, which is a residue that has potential benefit to human health. However, there are still few studies that seek to evaluate the composition and potential benefits of goat milk whey, even though it is a promising dairy source. Despite this, the large-scale generation of this waste can favor the environmental impact when improperly disposed of. Given this, the use of all content of dairy production can reverse this impact and increase the income of the dairy industry. Thus, this research prepared a powdered product based on goat's milk whey from the spray drying technique and evaluate its physicochemical composition by chemical analytical methods and protein profile through polyacrylamide gel electrophoresis. The elaborated product had a higher carbohydrate content than protein, and the identification of protein fractions showed that the most expressive bands represented beta-lactoglobulin and alpha-lactoalbumin. Therefore, the elaborated product has the potential to generate novel products for human consumption and with potential health benefits.

O queijo após processado gera o soro de leite, sendo este um resíduo que possui potencial benefício à saúde humana. No entanto, ainda são poucos os estudos que buscam avaliar a composição e os potenciais benefícios do soro de leite de cabra, mesmo esta sendo uma fonte láctea promissora. Apesar disso, a geração em larga escala deste resíduo pode favorecer o impacto ambiental quando descartado inadequadamente. Em vista disso, a utilização de todo conteúdo gerado na produção de lácteos pode reverter este impacto e aumentar o rendimento da indústria de laticínios. Diante disso, é importante buscar o desenvolvimento de novos produtos para favorecer a redução do impacto gerado. Assim, este trabalho teve como objetivo elaborar um produto em pó, à base de soro de leite de cabra a partir da secagem pela técnica de spray drying e avaliar sua composição físico-química por métodos químicos analíticos e perfil proteico através da eletroforese em gel de poliacrilamida. O produto elaborado apresentou maior teor de carboidratos do que proteína, e a identificação das frações proteicas mostrou que as bandas mais expressivas representavam beta-lactoglobulina e alfa-lactoalbumina. Portanto, o produto elaborado apresenta potencial para geração de novos produtos para consumo humano e com prováveis benefícios à saúde.

Yield and Technological Quality of Pirarucu Trimming Surimi According to the Number of Washing Cycles, Rice Flour Content, and Cooking Temperature.

This research aimed to optimize surimi production with innovative raw materials called pirarucu trimmings and broken rice grains, which are by-products from food industries. The effects of three independent variables (number of washing cycles, content, and cooking temperature of rice flour-RF) on surimi's physical, chemical, and technological qualities were investigated through a Box-Behnken design. The number of washing cycles affected yield (77-93%), moisture (55-67%), lipids (18-35%), protein (7.15-11.88%), whiteness (46.73-64.45), chroma (8.86-13.18), hue angle (80.79-93.12°), cohesiveness (0.40-0.61), springiness (0.51-0.99), and freeze stability after 4 weeks (85.16-96.53%). RF concentration affected moisture, lipids, cohesiveness, springiness, and freeze-thaw stability after 4 weeks. RF cooking temperature affected moisture, chroma, cohesiveness, and springiness. The optimal conditions for surimi production with high yield and overall quality were three washing cycles, 6% of RF, and RF cooking temperature at 85 °C. It reveals the promising potential of both by-products to be used as an ingredient in restructured products and contribute to improving agri-industry sustainability.

Combined UV-C Technologies to Improve Safety and Quality of Fish and Meat Products: A Systematic Review.

This study aimed to identify the best UV-C combined treatments for ensuring the safety and quality of fish and meat products. A total of 4592 articles were screened in the relevant databases, and 16 were eligible studies. For fish, the most effective treatments to reduce Gram-negative and Gram-positive bacteria were UV-C at 0.5 J/cm2 + non-thermal atmospheric plasma (NTAP) for 8 min (33.83%) and 1% Verdad N6 + 0.05 J/cm2 + vacuum packaging (25.81%), respectively. An oxygen absorber with 0.102 J/cm2 was the best combined treatment, reducing lipid oxidation (65.59%), protein oxidation (48.95), color (ΔE = 4.51), and hardness changes (18.61%), in addition to a shelf-life extension of at least 2 days. For meat products, Gram-negative bacteria were more reduced by nir-infrared heating (NIR-H; 200.36 µW/cm2/nm) combined with 0.13 J/cm2 (70.82%) and 0.11 J/cm2 (52.09%). While Gram-positive bacteria by 0.13 J/cm2 with NIR-H (200.36 µW/cm2/nm), 1, 2, or 4 J/cm2 with flash pasteurization (FP) during 1.5 or 3 s, and 2 J/cm2 with FP for 0.75 s (58.89-67.77%). LAE (5%) + 0.5 J/cm2 was promising for maintaining color and texture. UV-C combined technologies seem to be a cost-effective alternative to ensure safety with little to no quality changes in fish and meat products.

Production system influences color stability and lipid oxidation in gluteus medius muscle.

OBJECTIVE: We aimed to evaluate the color and oxidative stability of beef gluteus medius (GM) from cattle raised in organic and non-organic production systems. METHODS: The GM samples (n = 10) were obtained from organic (ORG; n = 5) or non-organic (NORG; n = 5) beef samples, sliced into 2.54-cm steaks, packaged in aerobic conditions, and stored for nine days at 4°C. ORG and NORG steaks were compared regarding myoglobin concentration, pH, instrumental color, delta E (ΔE), metmyoglobin reducing activity (MRA), and lipid oxidation on days 0, 5, and 9. RESULTS: Feeding system did not influence (p>0.05) the myoglobin concentration. ORG steaks exhibited greater (p<0.05) meat pH, yellowness, and MRA, whereas NORG steaks exhibited greater (p<0.05) redness, chroma, R630/580, delta E, and lipid oxidation. ORG and NORG steaks exhibited similar (p>0.05) lightness and hue angle. During storage, ORG and NORG exhibited an increase in muscle pH, hue angle, and lipid oxidation; and a decrease (p<0.05) in redness, yellowness, chroma, and color stability (R630/580). Both samples exhibited a stable (p>0.05) pattern for lightness and MRA. CONCLUSION: Therefore, the production system can affect beef color and lipid stability during storage.

Influence of harvest method on proximate composition, texture profile and protein oxidation of beef from grain-fed Nellore cattle

The influence of harvest method on proximate composition, protein oxidation, and texture profile of beef from Nellore cattle were investigated. Longissimus lumborum (LL) muscles were obtained from twelve grain-fed Nellore carcasses. The animals were slaughtered after stunning (STU; n=6) or without stunning (WST; n=6) and after 24 hours postmortem, the LL was sliced into 2.54-cm steaks, packed under aerobic conditions, and stored at 4°C for nine days. Proximate composition was analyzed on day 0, whereas protein oxidation (carbonyl content) and texture profile (hardness, chewiness, cohesiveness, and springiness) were evaluated on days 0, 3, 6, and 9. STU and WST steaks exhibited similar proximate composition, hardness, and chewiness (p > 0.05). WST steaks exhibited greater protein oxidation and lower cohesiveness than their STU counterparts on day 0 (p < 0.05). Concerning the storage period, WST steaks demonstrated a decrease in springiness and a more pronounced increase in cohesiveness than their STU counterparts (p < 0.05). These results indicated that the harvest method influenced LL protein oxidation and texture profile from Bos indicus cattle.(AU)

Essential oils block cellular entry of SARS-CoV-2 delta variant.

Aiming to fill a gap in the literature, we aimed to identify the most promising EOs blocking in vitro cellular entry of SARS-CoV-2 delta variant without conferring human cytotoxicity and provide insights into the influence of their composition on these activities. Twelve EOs were characterized by gas chromatography coupled to mass spectrometry. The antiviral and cytotoxicity activities were determined using the cell-based pseudoviral entry with SARS-CoV-2 delta pseudovirus and the XTT assay in HeLa cells expressing human angiotensin-converting enzyme 2 (HeLa ACE-2), respectively. Syzygium aromaticum, Cymbopogon citratus, Citrus limon, Pelargonium graveolens, Origanum vulgare, "Illicium verum", and Matricaria recutita showed EC50 lowered or close to 1 µg/mL but also the lowest CC50 (0.20-1.70 µg/mL), except "I. verum" (30.00 µg/mL). Among these, "I. verum", C. limon, P. graveolens and S. aromaticum proved to be promising alternatives for SARS-CoV-2 delta variant inhibition (therapeutic index above 4), which possibly was related to the compounds (E)-anetole, limonene and beta-pinene, citronellol, and eugenol, respectively.

An Optimization of Oregano, Thyme, and Lemongrass Essential Oil Blend to Simultaneous Inactivation of Relevant Foodborne Pathogens by Simplex-Centroid Mixture Design.

(1) Background: This study aimed to use the simplex-centroid mixture design methodology coupled with a microdilution assay to predict optimal essential oil (EO) formulations against three potential foodborne pathogens simultaneously through the desirability (D) function. (2) Methods: Oregano (ORE; Origanum vulgare), thyme (THY; Thymus vulgaris), and lemongrass (LG; Cymbopogon citratus) and their blends were evaluated concerning minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) for Salmonella enterica serotype Enteritidis, Escherichia coli and Staphylococcus aureus. (3) Results: THY combined with ORE or LG were the most promising EO formulations in inhibiting and killing each bacterium separately. Regarding the simultaneous effect, the optimal proportion for maximum inhibition was composed of 75% ORE, 15% THY, and 10% LG, while for maximum inactivation was 50% ORE, 40% THY, and 10% LG. (4) Conclusion: The multiresponse optimization allowed identifying an EO blend to simultaneously control three potential foodborne pathogens. This first report could be a helpful natural and green alternative for the industry to produce safer food products and mitigate public health risks.

Multivariate Nature of Fish Freshness Evaluation by Consumers.

The aim of the present study was to evaluate the sensory acceptability limit of refrigerated fish through a multivariate approach, involving classic physicochemical and bacteriological indicators and considering different consumer profiles. The results of the survival analysis demonstrated that, in general, consumers still considered the fish to be suitable for purchase (4.128 days of storage), despite being microbiologically unsuitable for consumption. However, the subsequent division of consumers into clusters indicated that women and individuals with high income and education levels tend to reject fish with few days of storage (3.650 days), mainly due to discoloration, despite still being microbiologically suitable for consumption. Thus, these segments present a safer behavior regarding the purchase of fresh fish. The influence of different frequencies of fish consumption and age of consumers on the assessment of fish freshness was not clarified. The responsibility for ensuring safe and healthy products at the point of sale must lie with the producers and distributors. However, improving consumers' ability to make good choices when buying fresh fish would bring social and economic benefits related to public health and to the seafood industry, because it would enable them to make relevant claims and demand their rights.

COVID-19 contamination through food: A study with Brazilian consumers of different socioeconomic and demographic characteristics.

This study aimed to investigate through free word association the perception of Brazilian consumers regarding the possibility of infection with the SARS-CoV-2 virus through food. One thousand individuals answered the questionnaire via an online platform. Most cited terms (hygiene-8%, fear-8%, caution-5%) and categories (negative attitudes and feeling-72% and sanitization-60%) were related to overall COVID-19 infection rather than their specific infection through the food. The perception of the possibility of risk of this type of cross-contamination was greater for male participants, within the food field, with high income (>10 minimum wages), and from the midwest region. Nonetheless, there are still doubts regarding this possibility, especially for participants with low income (≤10 minimum wages), females, higher education (≥secondary school), who exercise professional activity outside the food sector and from most regions of Brazil. Practical applications: Although the SARS-CoV-2 virus was discovered 2 years ago, the emergence of new variants such as Omicron has increased infection and mortality rates worldwide. A possible way of COVID-19 infection is cross-contamination through food handling and contact surfaces if preventive measures are not applied. In this context, understanding the consumer perception from a continental-size country such as Brazil, with a wide variety of socioeconomic profiles, is crucial to minimize the severe impacts of the pandemic. Our study demonstrates the need to disseminate scientific information in different media to reduce misinformation, especially social media because most Brazilian consumers had doubts and uncertainties about the possibility of COVID-19 infection from cross-contamination through food.

What Do Consumers Think About Foods Processed by Ultraviolet Radiation and Ultrasound?

This study aimed to investigate Brazilian consumers' perception concerning foods processed by ultraviolet (UV) radiation and ultrasound (US) and define consumer segments considering their socioeconomic characteristics and eating habits towards industrialized products through free word association tasks answered by 1004 participants via an online platform. UV- and US-treated foods were more frequently related to unfamiliar words/terms (21.51 and 36.95%) and negative associations (36.25 and 26.70%) than positive ones (29.89 and 24.20%), respectively. Unfamiliarity and health risk concerns were more reported for US-treated foods by women aged 18-25 and ≥46 with low income, and low and frequent industrialized products consumption, as well as for UV-treated foods by consumers ≤35 years old with low and medium income, and low and frequent industrialized products consumption. This indicates that more clear and trustworthy information is needed before introducing these products in the Brazilian market, mainly for potential target consumer groups identified in this study.

An Evaluation of the Potential of Essential Oils against SARS-CoV-2 from In Silico Studies through the Systematic Review Using a Chemometric Approach.

Essential oils (EOs) and their compounds have attracted particular attention for their reported beneficial properties, especially their antiviral potential. However, data regarding their anti-SARS-CoV-2 potential are scarce in the literature. Thus, this study aimed to identify the most promising EO compounds against SARS-CoV-2 based on their physicochemical, pharmacokinetic, and toxicity properties. A systematic literature search retrieved 1669 articles; 40 met the eligibility criteria, and 35 were eligible for analysis. These studies resulted in 465 EO compounds evaluated against 11 human and/or SARS-CoV-2 target proteins. Ninety-four EO compounds and seven reference drugs were clustered by the highest predicted binding affinity. Furthermore, 41 EO compounds showed suitable drug-likeness and bioactivity score indices (≥0.67). Among these EO compounds, 15 were considered the most promising against SARS-CoV-2 with the ADME/T index ranging from 0.86 to 0.81. Some plant species were identified as EO potential sources with anti-SARS-CoV-2 activity, such as Melissa officinalis Arcang, Zataria multiflora Boiss, Eugenia brasiliensis Cambess, Zingiber zerumbet Triboun & K.Larsen, Cedrus libani A.Rich, and Vetiveria zizanoides Nash. Our work can help fill the gap in the literature and guide further in vitro and in vivo studies, intending to optimize the finding of effective EOs against COVID-19.

Pomegranate (Punica granatum) peel fractions obtained by supercritical CO2 increase oxidative and colour stability of bluefish (Pomatomus saltatrix) patties treated by UV-C irradiation.

The sequential fractionation by supercritical-CO2 (SC-CO2) was applied to obtain fractions enriched in bioactive compounds of pomegranate peel, and we investigated if pomegranate peel extract and fractions would be effective to inhibit lipid and protein oxidation, and discolouration of bluefish patties stored at 4 °C for 9 days, after UV-C irradiation. The non-fractionated SC-CO2 extract from pomegranate peel was rich in phenolic compounds, mainly ellagitannins, besides, it possessed lipophilic compounds such as tocopherols and ß-carotene. These compounds were successfully separated by the fractionation protocols, in a lipid fraction concentrated in lipophilic compounds, and one or two fractions enriched with phenolic compounds, especially ellagitannins. The lipid fraction and the high phenolics fraction from pomegranate peel were then as effective as the synthetic antioxidant BHT in avoiding bluefish patties oxidation during refrigerated storage. Our data indicates that pomegranate peel fractions could be used to replace a synthetic antioxidant in fish meat.

Combined Effect of Modified Atmosphere Packaging and UV-C Radiation on Pathogens Reduction, Biogenic Amines, and Shelf Life of Refrigerated Tilapia (Oreochromis niloticus) Fillets.

This study investigated the isolated effect of modified atmosphere packaging (MAP; 50% CO2 and 50% N2) and ultraviolet radiation (UV; 0.30 J/cm2) as well as their combined (MAP/UV) effect on reduction of Salmonella typhimurium and Escherichia coli O157:H7, biogenic amines (BA), and on shelf life of tilapia fillets stored at 4 ± 1 °C for 10 days. UV samples had the highest reduction of S. typhimurium (1.13 log colony forming units/g; CFU/g) and E. coli O157:H7 (0.70 log CFU/g). MAP and MAP/UV reduced the growth of S. typhimurium in 0.50 log CFU/g and did not affect the growth of E. coli O157:H7. UV, MAP, and MAP/UV increased lag phase and/or generation time of all evaluated bacterial groups, decreased pH values, ammonia formation, texture changes, and, in general, the BA formation throughout storage period, and, therefore, UV, MAP, and MAP/UV extended the shelf life for two, three, and at least five days, respectively. MAP/UV, MAP, and UV decreased redness, MAP/UV and MAP increased yellowness and lipid oxidation, while UV did not affect it. MAP/UV demonstrated promising results for shelf life extension; however, different gas ratios in combination with other ultraviolet radiation type C (UV-C) doses should be investigated to reach the highest microbiological safety and maintenance of the overall quality of tilapia fillets.

The Effect of Different Packaging Systems on the Shelf Life of Refrigerated Ground Beef.

Abstract: The aim of this study was to investigate the effects of different packaging systems on the shelf life of refrigerated ground beef. The ground beef samples were packaged as follows: AA (100% ambient air), 90O2:10CO2 (90% O2 and 10% CO2), 80O2:20CO2 (80% O2 and 20% CO2), 70O2:30CO2 (70% O2 and 30% CO2), 60O2:40CO2 (60% O2 and 40% CO2), 50O2:50CO2 (50% O2 and 50% CO2), 100O2 (100% O2), and VP (vacuum packaging). All treatments were analyzed daily for O2 and CO2 levels, pH, filtration time, total volatile basic nitrogen (TVB-N), aerobic mesophilic heterotrophic bacteria (AMHB), and aerobic psychrotrophic heterotrophic bacteria (APHB) over 20 days at 2 °C. All MAP systems had a decrease of O2 and an increase of CO2 levels during storage period (p < 0.05). Overall, the MAP systems were similarly able to decrease the pH and retard the increase of TVB-N and filtration time over the storage period (p > 0.05). Moreover, the MAP systems increased the lag phase and/or the generation time of both AMHB and APHB, extending the shelf life by 3 (90O2:10CO2), 4 (70O2:30CO2 and 100O2), and 5 days (80O2:20CO2, 60O2:40CO2, 50O2:50CO2, and VP). All MAP systems were equally effective in retarding physicochemical degradation; however, 80O2:20CO2, 60O2:40CO2, 50O2:50CO2, and VP were the most effective in impairing bacterial growth and extending the shelf life of ground beef stored under refrigeration.

Combined effect of oxygen-scavenger packaging and UV-C radiation on shelf life of refrigerated tilapia (Oreochromis niloticus) fillets.

This study investigated the physicochemical, instrumental and bacterial parameters of tilapia fillets subjected to oxygen-scavenger packaging, alone or in combination with UV-C radiation at two doses (0.102 and 0.301 J/cm2), stored at 4 ± 1 °C for 23 days. The oxygen scavenger, both UV-C doses, and the oxygen scavenger combined with UV-C, independently of the dose, extended the shelf life in 5, 6 and 7 days, respectively, by decreasing the bacterial growth rate and the formation of degradation compounds (e.g., TVB-N and ammonia). Oxygen-scavenger packaging, alone or in combination with UV-C at 0.102 J/cm2 and 0.301 J/cm2 showed lower amounts of free amino acids (FAA; 34.39, 34.49 and 34.50 mg L-lysine/kg fish tissue, 3.63, 3.57 and 3.61 mg L- ornithine/kg fish tissue, 27.52, 27.63 and 27.67 mg L-arginine/kg fish tissue), biogenic amines (BA; 3.81, 3.87 and 3.89 mg cadaverine/kg fish tissue, 12.88, 12.91 and 12.86 mg putrescine/kg fish tissue, 2.41, 2.44 and 2.47 mg spermidine/kg fish tissue), redness (2.53, 2.55 and 2.59), yellowness (6.65, 6.69 and 6.72), lipid oxidation (1.52, 1.53 and 1.58 mg malondialdehyde/kg fish tissue) and protein oxidation (5.06, 5.11 and 5.18 nmol carbonyls/mg protein), with higher hardness (3273.41, 2652.98 and 2687.57 g) than control (air packaging; 41.97 mg L-lysine/kg fish tissue, 4.83 mg L- ornithine/kg fish tissue, 37.33 mg L-arginine/kg fish tissue, 4.82 mg cadaverine/kg fish tissue, 16.56 mg putrescine/kg fish tissue, 3.21 mg spermidine/kg fish tissue, 4.26 of redness, 8.17 of yellowness, 2.88 mg malondialdehyde/kg fish tissue, 9.44 nmol carbonyls/mg protein and 2092.58 g of hardness), respectively, on day 13 of storage when the control fillets were unfit for consumption (7 log CFU/g) (p < 0.05). However, in the same day of storage, both UV-C doses had similar values for BA (p > 0.05), higher amounts of FAA (44.28 and 44.13 mg L-lysine/kg fish tissue, 5.16 and 5.12 mg L- ornithine/kg fish tissue, 40.20 and 40.28 mg L-arginine/kg fish tissue), redness (4.86 and 5.33), yellowness (9.32 and 10.01), lipid oxidation (3.09 and 3.52 mg malondialdehyde/kg fish tissue) and protein oxidation (10.27 and 11.93 nmol carbonyls/mg protein), as well as lower hardness (1877.54 and 1767.39 g), respectively, than control fillets (p < 0.05). The combined preservation methods were the most effective in extending the shelf life and prolonging the physicochemical quality of the refrigerated tilapia fillets and the O2 scavenger proved to be a potential alternative to prevent the negative changes induced by both UV-C doses.

Instrumental color and oxidative stability of light and dark muscles of Nile tilapia / Cor instrumental e estabilidade oxidativa de músculos claros e escuros de tilápia do Nilo

ABSTRACT: The aim of the present study was to compare the color and oxidative stability of light (LM) and dark (DM) muscles of Nile tilapia (Oreochromis niloticus) stored at 4 °C for eight days. Five different trials of LM and DM samples were analyzed for instrumental color attributes (lightness, redness and yellowness), including the surface color stability through ratio of reflectance at 630/580 nm (R630/580), myoglobin concentration, total lipid content, fatty acid profile, metmyoglobin reducing activity (MRA), pH, lipid oxidation and protein oxidation. Results of the present study indicated that DM of Nile tilapia (Oreochromis niloticus) present lower oxidative and color stability during refrigerated storage than LM.

RESUMO: O objetivo do presente estudo foi comparar a estabilidade de cor e oxidativa de músculos claros (LM) e escuros (DM) de tilápia do Nilo (Oreochromis niloticus) armazenados a 4° C por oito dias. Cinco repetições diferentes de amostras de LM e DM foram analisadas quanto aos atributos instrumentais de cor (luminosidade, teor de vermelho e teor de amarelo), incluindo a estabilidade de cor na superfície através da razão de refletâncias nos comprimentos de onda 630 e 580 nm (R630/580), concentração de mioglobina, lipídios totais, perfil de ácidos graxos, atividade de redução da metamioglobina (MRA), pH, oxidação lipídica e oxidação proteica. Os resultados do presente estudo indicam que músculos escuros (DM) de tilápia do Nilo (Oreochromis niloticus) apresentam menor estabilidade oxidativa e de cor durante o armazenamento refrigerado, quando comparados aos músculos claros (LM).