Nanoencapsulation Approach to Improve Antimicrobial and Antioxidant Activity of Thyme Essential Oil in Beef Burgers During Refrigerated Storage

In this study, thyme essential oil (TEO) loaded chitosan nanoparticles (CS-NP-TEO) are prepared by a two-step process including oil/water emulsion and ionic gelation. Five batches of burgers were prepared by following formulation: control (without any TEO), F-0.05-TEO (0.05 % of free TEO), F-0.1-TEO (0.1 % of free TEO), E-0.05-TEO (0.05 % of encapsulated TEO), E-0.1-TEO (0.1 % of encapsulated TEO), and AA-0.05 (0.05 % of ascorbic acid). All samples treated with TEO significantly reduced the population of investigated microbial counts (P?<?0.05) compared to the control during 8 days of storage. At the end of storage, E-0.05-TEO and E-0.1-TEO, presented, respectively, 2.2 and 3 log cycles reduction of Enterobacteriaceae, along with 3.1 and 3.7 log cycles reduction of Staphylococcus aureus. Oxymyoglobin content and redness values reduced with the increase of storage time for all samples. However, AA-0.05 and E-0.1-TEO samples were more efficient at inhibiting discoloration in comparison with E-0.05-TEO and burgers treated with free TEO after 6th day of storage. A significant improvement (P?<?0.05) in the reduction of thiobarbituric acid reactive substances (TBARS) amount was found for all TEO treated burgers in comparison to control samples after 8 days chilled storage. According to the results of sensory analyses, F-0.1-TEO and AA-0.05 samples at 4 days and F-0.05-TEO sample at 8 days of storage were rejected by assessors and considered as an unacceptable case. On the basis of our results, the encapsulation of TEO in chitosan nanoparticles may be a promising technology for the control of undesirable microbial, chemical, and sensorial changes in meat products.     

Sensory attributes and texture profile of beef burgers with gari

Beef burgers were produced using gari to substitute beef in the product formulations at 0% (control), 10%, 15% and 20% respectively. Cooking yield increased significantly (p<0.05) with increasing use of gari. Sensory evaluation of the products revealed significant (p<0.05) differences for acceptability and texture attributes. The acceptability score for burgers produced with 15% gari was not significantly different (p>0.05) from the control without gari. Using gari had no significant (p>0.05) effect on flavor and odor attributes of beef burgers. Texture profile analysis of burgers showed significant (p<0.05) reductions in hardness, springiness, gumminess and chewiness at all levels of substituting beef with gari. Production cost of burgers reduced by 9%, 14% and 18% respectively using 10%, 15% and 20% gari in burgers. The results suggest that gari has promising potential for use in comminuted meat products.     

Influence of 10-MeV E-Beam Irradiation and Vacuum Packaging on the Shelf-Life of Grass Carp Surimi

The effects of 10-MeV E-beam (0, 1, 3, 5, and 7 kGy) irradiation and vacuum packaging on extending the shelf-life of grass carp surimi stored at 4 °C were evaluated basing on the total viable counts (TVC), physiochemical 2-thiobarbituric acid reactive substance (TBARS), total base nitrogen (TVB-N), biogenic amines (BAs), texture (TPA) and color, and sensory changes in surimi samples. The results showed that comparing the control samples, the TVC and TVB-N content in surimi were significantly (p?<?0.05) decreased by irradiation with different doses. Irradiation significantly (p?<?0.05) inhibited the increase of putrescine (PUT), cadaverine (CAD), histamine (HIM), and tyramine (TYM) contents during storage. However, these parameters were significantly (p?<?0.05) increased with storage time. After irradiation, the samples generally had higher lightness and lower a ^* and b ^* values and lower hardness and chewiness significantly (p?<?0.05). Based on the sensory analysis, unfavorable ‘metal odor’ or ‘irradiated odor’ was observed in surimi irradiated at 5 and 7 kGy.     

Tuna Burgers Preserved by the Selected <Emphasis Type="Italic">Lactobacillus paracasei</Emphasis> IMPC 4.1 Strain

The use of protective microbial strains in combination with modified atmosphere packaging (MAP) and refrigerated storage on the shelf life of tuna burgers was investigated. Preliminary, the protective ability of three lactic acid bacteria (LAB) cultures (Lactobacillus casei, Lactobacillus paracasei, and Lactobacillus plantarum) have been assessed on ready-to-cook tuna burgers. Among them, L. paracasei showed the best preserving performance and significantly controlled both aerobic mesophilic bacteria and Pseudomonas spp. growth. Subsequently, the efficacy of the selected LAB culture under MAP conditions (5% O₂ and 95% CO₂) was assessed evaluating microbial and sensory quality, as well as volatile aldehyde content. Results indicated that the shelf life of burgers containing L. paracasei and packaged under MAP was 4 days longer than the control (shelf life about 6 days) and that the applied procedure represents an effective approach for the mild preservation of fish products.     

Preservative Effect of a Previous High-Pressure Treatment on the Chemical Changes Related to Quality Loss in Frozen Hake (<Emphasis Type="Italic">Merluccius merluccius</Emphasis>)

The objective of this study was the quality loss inhibition of hake (Merluccius merluccius) during the frozen storage. For it, the effect of a previous high-pressure (HP) treatment (150–450 MPa for 2 min) was analysed throughout a 5-month storage at ? 10 °C. Quality changes were monitored by complementary chemical analyses. Inhibition (p < 0.05) of dimethylamine (DMA), free fatty acid (FFA), formaldehyde (FA), trimethylamine, total volatile amine and fluorescent compound (tertiary lipid oxidation compound) formation was concluded by previous pressure treatment according to the one-way ANOVA analysis. On the contrary, no effect (p > 0.05) on the K value, polyene index and formation of peroxides and thiobarbituric acid reactive substances was achieved. Additionally, a multifactor ANOVA test (pressure and frozen storage time effects; i.e. comparison among HP treatments) showed an inhibitory effect (p < 0.015) on DMA and FFA formation, this effect increasing with pressure level applied. This inhibitory effect on the formation of such molecules related to quality loss can be explained on the basis of the damage caused to different kinds of enzymes such as trimethylamine oxide demethylase, lipases and phospholipases, so that their activity during the subsequent frozen storage would decrease. The work here presented provides for the first time information concerning the employment of HP technology to inhibit the DMA, FA and FFA formation during the frozen storage of hake. Further research focussed on commercial frozen conditions (? 18 °C) and including sensory and nutritional aspects is foreseen.     

Relationships Between Textural Modifications,Lipid and Protein Oxidation and Sensory Attributes of Refrigerated Turkey Meat Sausage Treated with Bacteriocin BacTN635

In this study, bacteriocin “BacTN635” was used to maintain quality and extend shelf life of refrigerated turkey meat sausage. Connections between lipid and protein oxidations and instrumentally textural changes using Bayesian networks during storage of turkey meat sausage were also studied. BacTN635 slowed down metmyoglobin and carbonyl group accumulation and delayed the disappearance of sulphydryl proteins (P < 0.05) in turkey meat sausage. This bacteriocin led to a decrease in primary and secondary lipid oxidation (P < 0.05) and enhanced texture characteristics of sausage by reducing hardness (P < 0.05) and controlling the elasticity lose during refrigeration. We have also investigated the correlations between protein and lipid oxidation and instrumentally measured the parameters of turkey meat sausage treated by BacTN635. The developed model, based on Bayesian network techniques, can automatically learn emerging models in data to explain protein and lipid oxidation and texture modification relationships. Equally, sensorial parameters were used for constructing regression models to predict overall acceptability. In conclusion, BacTN635 could be a promising tool for extending the safety and quality of refrigerated turkey meat sausage. This bacteriocin could be a strong candidate for future applications in a wide range of meat products.     

Kinetic Modeling of Texture and Color Changes During Thermal Treatment of Chicken Breast Meat

Heat treatment is commonly applied as a primary method for ensuring the microbial safety of poultry meat and to enhance its palatability. Although texture and color of cooked chicken breast meat are important quality parameters for the consumers that need to be controlled during thermal processing, studies assessing the temperature-time-dependent quality changes during thermal treatment are lacking. This work aims to investigate the texture and color changes of chicken breast meat during thermal processing and to develop kinetic models that describe these changes. We studied the storage modulus changes of chicken breast meat as function of temperature. The storage modulus increases from 55 °C until leveling off in an equilibrium value above 80 °C, which was attributed to microstructure changes and described with a sigmoidal function. The changes in the texture (TPA) and color (CIE L ^* a ^* b ^* ) of chicken breast meat were measured as function of temperature and time. The texture and color parameters show a rise with heating time until reaching an equilibrium value, while the rate of change increased with temperature. Kinetic models that take the non-zero equilibrium into account were developed to describe the color (lightness) and texture (hardness, gumminess, and chewiness) changes with heating time and temperature. The kinetic models provide a deeper insight into the mechanisms of texture and color changes during thermal treatment. They can be used to predict the texture and color development of chicken breast meat during thermal processing and, thus, help to optimize the process.     

Effect of ground poppy seed as a fat replacer on meat burgers

Poppy seed paste was used in koefte production as an animal fat replacer and efficacy of using poppy seed was investigated. The use of ground poppy seed in formulation of meat burgers had no effect on the moisture content of uncooked meat burgers; however, it did have a significant effect (p<0.05) on the fat content of meat burgers. Ground poppy seed addition significantly affected (p<0.05) cooking yield, moisture retention, and fat retention of meat burgers. Ground poppy seed addition significantly decreased (p<0.05) saturated fatty acid contents as the amount of ground poppy seed increased in meat burgers. A strong significant decrease (p<0.05) on the cholesterol content of meat burgers with ground poppy seed addition was observed. Samples having 20% ground poppy seed had significantly better texture and juiciness score (p<0.05) than any other sample which could be explained by increased moisture retention. Replacing animal fat with ground poppy seed paste is effective and may pave the way for an innovative meat product.     

High-Pressure Pretreatment to Improve the Water Retention of Sodium-Reduced Frozen Chicken Breast Gels with Two Organic Anion Types of Potassium Salts

The effect of high-pressure pretreatment (HPP, 100–300 MPa) before heating on the water holding capacity (WHC) and cooking loss (CL) of sodium-reduced (1.35% NaCl) frozen chicken breast gels with the organic anion types potassium lactate (KL-gel) and potassium citrate (KC-gel) was investigated. The results showed that 100–300 MPa could significantly decrease the CL of both gels, and 200 MPa increased the WHC of the KC-gel (P?<?0.05). HPP could decrease the storage modulus (G′) of meat batters, increase the thermal stability of their proteins, facilitate gelation with a dense and uniform microstructure, and immobilize free water, thus improving the gel’s water retention. The water retention of the pressurized sodium-reduced gel varied with the organic anion types of salts. The water retention was better with pressurized KC-gel than with KL-gel, resulting from higher pH and thermal stability of the batters. These results indicate that proper HPP could improve the water retention of sodium-reduced meat gels with organic potassium salts, thus increasing the economic benefit and properties of sodium-reduced products from frozen meat.     

Sensory attributes and texture profile of beef burgers with gari

Beef burgers were produced using gari to substitute beef in the product formulations at 0% (control), 10%, 15% and 20% respectively. Cooking yield increased significantly (p < 0.05) with increasing use of gari. Sensory evaluation of the products revealed significant (p < 0.05) differences for acceptability and texture attributes. The acceptability score for burgers produced with 15% gari was not significantly different (p > 0.05) from the control without gari. Using gari had no significant (p > 0.05) effect on flavor and odor attributes of beef burgers. Texture profile analysis of burgers showed significant (p < 0.05) reductions in hardness, springiness, gumminess and chewiness at all levels of substituting beef with gari. Production cost of burgers reduced by 9%, 14% and 18% respectively using 10%, 15% and 20% gari in burgers. The results suggest that gari has promising potential for use in comminuted meat products.     

Deposit Generation During Camel and Cow Milk Heating: Microstructure and Chemical Composition

The aim of this study is to identify the chemical composition and the microstructure of the deposits obtained after heating camel and cow milks at 80 °C for 60 min using a laboratory-scale device. Like cow milk, camel milk was affected by heat treatment with the reduction of the non-casein nitrogen content reflecting the denaturation of camel whey proteins. The composition of the deposits generated during heating camel and cow milks at 80 °C for 60 min revealed that while camel deposit contained 57 % w/w protein, cow deposit showed a higher protein content of 69 % w/w. The mineral content was 35 % w/w for camel deposit which was higher than that of cow sample, which was 28 % w/w. SEM of both deposits showed a familiar structure of a protein deposit with large clumps composed of smaller aggregates. Camel deposit showed an amorphous structure due to its deficiency in β-lactoglobulin.     

Mass Transfer Kinetic and Quality Changes During High-Pressure Impregnation (HPI) of Jumbo Squid (<Emphasis Type="Italic">Dosidicus gigas</Emphasis>) Slices

Jumbo squid is an important marine resource commercialized in Chile as well as American countries such as Perú, México, and USA. In order to find the best conditions for prevention of squid meat degradation, this study presented the simultaneous application of high hydrostatic pressure and osmotic dehydration (high-pressure impregnation (HPI)) on jumbo squid (Dosidicus gigas) slices. Diffusion coefficients for both components water and solids are improved by the high-pressure processing. The pressures used were 100, 250, and 400 MPa for a 15 g/100 mL salt concentration for time intervals of 30 s. The mathematical expressions used for mass transfer simulations of both water and salt were those corresponding to Newton, Henderson and Pabis, Page, and Weibull models, where the Weibull model presented the best fitted to the experimental data for both components. As to quality parameters studied for texture profile analysis, the treatment at 250 MPa yielded on the samples a minimum hardness, whereas springiness, cohesiveness, and chewiness at 100-, 250-, and 400-MPa treatments presented statistical differences regarding unpressurized samples. The color parameters L^* (lightness) increased; however, b^* (yellowish) and a^* (reddish) parameters decreased when increasing pressure level. This way, samples presented a brighter aspect and a mildly cooked appearance. The results presented in this study could support the potential of high hydrostatic pressure application as a technique novel for other compound impregnation under high pressure.     

Combined Effect of Icing Medium and Red Alga <Emphasis Type="Italic">Gracilaria verrucosa</Emphasis> on Shelf Life Extension of Indian Mackerel (<Emphasis Type="Italic">Rastrelliger kanagurta</Emphasis>)

Flake ice refrigeration is a conventional but commonly employed technique to slow down fish spoilage and deterioration of nutritional values and sensory properties during chilled storage. In the present study, a methanolic extract of red alga Gracilaria verrucosa was characterised, and functional groups, such as alkenes, aldehydes, nitriles, galactans and galactose-4-sulphate were found. Subsequent identification of active compounds revealed the presence of potent preservative agents, such as butylated hydroxytoluene, sulfurous acid, 1,2-propanediol, benzeneacetic acid, cyclononasiloxane and tetracosamethyl-cyclododecasiloxane. The effect of incorporating G. verrucosa at two different concentrations (0.67 and 2.5 g lyophilised alga/L aqueous solution) in the icing medium was tested for the preservation of Indian mackerel (Rastrelliger kanagurta), compared to preservation in traditional ice prepared only from water. Microbial, chemical and sensory qualities were monitored in Indian mackerel chilled in ice with and without G. verrucosa during 15 days storage period. Inhibitory effects (p?<?0.05) on the microbial proliferation (mesophilic and psychrophilic bacteria) and chemical markers of fish deterioration (pH, TVB-N, TMA-N and biogenic amines) were evidenced for ice containing both concentrations of G. verrucosa, respectively, relative to the control medium. The sensory score acceptability limit reached 11 days for Indian mackerel stored in traditional ice and 15 days for Indian mackerel stored in ice with G. verrucosa extract. Thus, the icing medium containing G. verrucosa extract improves the quality and safety of Indian mackerel during storage and can be explored by the seafood industry as a biopreservative.     

Quality Enhancement of Chilled Fish by Including Alga <Emphasis Type="Italic">Bifurcaria bifurcata</Emphasis> Extract in the Icing Medium

Bifurcaria bifurcata is a widely extended brown macroalga, whose antimicrobial and antioxidant properties have previously been described. In this study, ethanolic extracts of B. bifurcata were included in the icing medium employed for the chilled storage of megrim (Lepidorhombus whiffiagonis). For it, two different concentrations of this brown macroalga extract (0.67 and 2.50 g lyophilized alga L^?1 aqueous solution; B-1 and B-2 batches, respectively) were tested for a 14-day storage. The effect of the alga extract was compared with a counterpart batch stored in traditional ice prepared only from water (B-0 batch). Significant (p < 0.05) inhibitions of microbial activity (aerobes, psychrotrophs, lipolytic bacteria, proteolytic bacteria and Enterobacteriaceae) as well as of pH and trimethylamine formation were observed as a result of the incorporation of the alga extract in the icing medium, being this effect especially relevant in the B-2 batch. Concerning lipid damage development, a significantly (p < 0.05) lower formation of free fatty acids (lipid hydrolysis development) and of fluorescent compounds (tertiary lipid oxidation development) in samples corresponding to both alga-including batches could also be observed; this inhibitory effect was more intense in fish belonging to the B-2 batch. The icing medium proposed in this work constitutes a promising strategy in order to apply algae extracts to enhance fish quality retention during the different steps of storage and commercialization of marine species.     

Modeling the Inactivation of <Emphasis Type="Italic">Listeria innocua</Emphasis> and <Emphasis Type="Italic">Escherichia coli</Emphasis> in Fresh-Cut Tomato Treated with Pulsed Light

The effectiveness of pulsed light (PL) treatments to inhibit microorganisms on fresh-cut tomatoes (Lycopersicon esculentum Mill., cv. Daniela) was investigated. Tomato slices inoculated with Escherichia coli or Listeria innocua were exposed to PL treatments (4, 6, or 8 J cm^?2 fluence) and kept cold at 4 °C for 20 days. L. innocua and E. coli counts, gases in the headspace of the containers (O₂ and CO₂), pH, titratable acidity, and soluble solid content were monitored throughout the cold storage. The PL treatments reduced significantly (p < 0.05) initial loads of both microbes. The effect of the PL fluence on the survival number of microoganisms was described by a log-linear model (R ² = 0.849–0.999). At any fixed time within the cold storing, the microbial counts for untreated samples were always higher than those cut tomatoes that had been previously PL-treated. The behavior of L. innocua and E. coli during the storage were well adjusted (R ² > 0.930) by Gompertzian models; the studied microorganisms exhibited different patterns during the storage period. On the other hand, O₂ and CO₂ partial pressures in containers with fresh-cut tomatoes were also significantly affected by PL treatments (p < 0.05). The highest PL fluence caused the greatest changes of O₂ and CO₂ contents. In addition, the application of PL triggered an acceleration of the O₂ consumption during the cold stage. PL treatments might be used to effectively extend the safety of fresh-cut tomatoes over 12 days of storage against E. coli and L. innocua growth.     

Changes in Texture and Flavor of Red Hake Sticks As Affected by Frozen Storage Form

Red hake (Urophycis chuss) was processed into frozen blocks from which sticks were made at various times so that the samples tested had been stored at – 18°C either as sticks or blocks or a combination of the two over a 9-month period. Sensory panelists found highly significant differences (p<0.001) among storage periods (3, 6, 9, months) for both flavor and texture. Storage form (stick or block), however, had little apparent effect on changes in flavor and texture. Cooking method had a significant effect on flavor (p<0.05) and on texture (p<0.001). Warner-Bratzler shear measurements were shown.     

Quality Enhancement of Chilled Lean Fish by Previous Active Dipping in <Emphasis Type="Italic">Bifurcaria bifurcata</Emphasis> Alga Extract

The present study addressed the quality enhancement of chilled fish by applying a preliminary dipping treatment containing a bioactive extract of the alga Bifurcaria bifurcata. Megrim (Lepidorhombus whiffiagonis) specimens were dipped in ethanolic–aqueous solutions containing two different concentrations of the alga extract (high: HAC batch and low: LAC batch). Two types of control batch were considered (ethanol–water dipping and no dipping). Microbial, chemical and sensory qualities were monitored in fish throughout a 13-day storage period. An inhibitory effect (p?<?0.05) of the dipping treatment (washing and the presence of alga extract) on microbial activity was observed, as determined by microbial (Enterobacteriaceae, lipolytic bacteria and psychrotrophs) and chemical (trimethylamine and free fatty acid formation) analyses. In most cases, this effect was found to be more intense for prolonged storage times and in fish specimens corresponding to the HAC batch. However, the combined effect of washing and the inclusion of alga extract in the dipping medium did not affect (p?>?0.05) the rate of lipid oxidation events during storage. Interestingly, average scores revealed increased sensory quality in megrim corresponding to the HAC batch for prolonged storage (9–13 days). Consequently, the use of a bioactive extract of B. bifurcata alga as a preliminary dipping treatment can be considered of interest for further fish storage due to both its simplicity and beneficial effects on fish quality enhancement.     

Combined Use of Ultrasound and Vanillin to Improve Quality Parameters and Safety of Strawberry Juice Enriched with Prebiotic Fibers

In this work, a previously optimized preservation treatment (vanillin = 1.25 mg/mL; ultrasound = 7.5 min, 40 kHz, 180 W) was applied to strawberry juice enriched with inulin and oligofructose. The evolution of microbial, nutritional, and sensory parameters of treated juices was studied. It was confirmed that the inclusion of inulin and oligofructose had no negative implication regarding the quality of fresh juice. Furthermore, the prebiotic addition maintained sensory attributes of the product. The applied preservation treatment improved almost every quality attribute during storage, reducing microbial development, especially lactic acid bacteria and yeast and mold growth, which rapidly grew in untreated juices. Nutritional quality was also improved by the treatment as total polyphenol and total flavonoid content were increased and ascorbic acid content losses were reduced during storage, indicating higher antioxidant capacity. Overall, the evaluated sensory attributes of treated juices were deemed acceptable (>2.5). The addition of vanillin imparted pleasant flavor notes to the juice, compatible with the fruit product. Also, the performance of the treated juice was evaluated against postharvest contaminations with pathogens of interest in the food industry and of health concern (Escherichia coli O157:H7 and Listeria monocytogenes, evaluated through the surrogate Listeria innocua). The optimized treatment was able to reduce the counts of these microorganisms during storage reaching undetectable values after 7 days of storage. Thus, the combination of vanillin and ultrasound could be a feasible alternative to ensure safety and improve quality parameters of strawberry juice enriched with prebiotic fibers.     

Characterization of Biodegradable Films Based on <Emphasis Type="Italic">Salvia hispanica</Emphasis> L. Protein and Mucilage

Biodegradable films of chia by-products (mucilage and protein-rich fraction (PF)) incorporated with clove essential oil (CEO) were obtained and characterized. The effects of polymer concentration (PC; 1.0–3.0 %, w/v) and CEO concentration (0.1–1.0 %, v/v) were evaluated as well as the pH (7–10), using a 2³ factorial design with four central points. The films exhibited moisture values between 11.6 and 52.1 % (d.b.), which decreased (p?<?0.05) with increasing PC and CEO. The thickness of the films increased (p?<?0.05) with increasing PC. PC and pH influenced (p?<?0.05) the lightness (L) and variation in color between red and green (a). The orientation of the color to yellow-blue hues (b) decreased significantly (p?<?0.05) with increasing PC. Transparency was significantly lower and higher (p?<?0.05) than PC and CEO, respectively. The film surface morphology was evaluated using atomic force miscrocope images, and thermogravimetric analysis (TGA) was performed to study the thermal stability of the films. The displacement and tensile strength were significantly lower (p?<?0.05) at higher concentrations of CEO, this variable being the only one with a significant effect. The chemical composition of the films was confirmed utilizing Fourier transform infrared (FTIR) spectroscopy. The proportion of CEO added to the films had a significant influence on antimicrobial activity, inhibiting the growth of both Escherichia coli and Staphylococcus aureus.