Use of antioxidants to minimize rancidity in pressurized and cooked chicken slurries

Effects of Supercritical CO2 Treatment on Color, Lipid Oxidation, Heme Iron, Non-Heme Iron and Metmyoglobin Contents in Ground Pork

The color, lipid oxidation, heme iron (HI) and non-heme iron (NHI) contents, metmyoglobin content and Soret band of myoglobin of ground pork subjected to supercritical CO2 treatment under different conditions, or to heat treatment (40°C, 2 h) and subsequent storage at 4°C were evaluated during 9-day period. Supercritical CO2 treatment significantly increased CIE L* and CIE b* values of ground pork during subsequent storage, while the HI content was slightly affected. In general, CIE a* value and metmyoglobin content were decreased. Supercritical CO2 treatment for 2 h could increase the thiobarbituric acid-reactive substances (TBARS) value, while treatment for 1 h or less had no effect. The NHI content could be increased only after treatment at above 40°C or 17.2 MPa for 2 h. The Soret band of myoglobin was shifted to longer wavelength. Increasing treatment temperature from 35°C to 45°C could increase CIE L*, CIE a*, CIE b* and TBARS values, HI and NHI contents of the ground pork, while decreasing metmyoglobin content. As the treatment pressure increased from 13.8 MPa to 20.7 MPa, CIE b* and TBARS values were decreased, while the NHI and metmyoglobin contents were increased. However, the other parameters were unchanged. Extending exposure time from 0.5 h to 2 h could increase CIE L*, CIE b* and TBARS values, HI contents, while decreasing CIE a* value and metmyoglobin content. Correlation analysis showed that the TBARS value was significantly and negatively correlated with the HI content or metmyoglobin content in samples treated at 40°C or above for 2 h.

Adsorption of free radical TEMPO onto Al2O3 nanoparticles and evaluation of radical scavenging activity

This study describes the adsorption of free radical TEMPO onto Al₂O₃ nanoparticles in the solvents with different polarities including DMF, methanol, acetone, THF, petroleum ether and n-hexane at ambient temperature to evaluate the radical scavenging activity. The adsorption percentage of radical is calculated by measuring the maximum adsorption intensity of the ultraviolet (UV) absorption spectrum of TEMPO in the presence and the absence of Al₂O₃ nanoparticles. The morphology of Al₂O₃ nanoparticles before and after adsorption of TEMPO is studied using transmission electron microscopy (TEM), X-ray diffraction (XRD) and Fourier-transform infrared (FT-IR) spectroscopy. The adsorption energy and other thermochemical data for the adsorption of TEMPO over different active sites of Al₂O₃ are estimated via dispersion corrected density functional theory (DFT + Disp). The donor-acceptor interactions between Al₂O₃ and TEMPO are calculated using natural bond orbital (NBO) theory. It is found that Al₂O₃ nanoparticles have efficient radical scavenging activity (RSA) in the range of 50-72%. Approximately, a linear relationship between dielectric constant of solvent and the absorption percentage of TEMPO over Al₂O₃ nanoparticles is achieved. So that with decreasing the polarity of solvent, the adsorption of TEMPO onto Al₂O₃ nanoparticles is increased. The adsorption of TEMPO over Lewis acidic sites of Al₂O₃ is more favored than Brønsted acidic and basic sites. The comparison between experimental and calculated IR spectra of TEMPO/Al₂O₃ complexes provides the good evidence for adsorption of TEMPO onto the surface of Al₂O₃ nanoparticles.

High-pressure processing of meat: Molecular impacts and industrial applications

High-pressure processing (HPP) has been the most adopted nonthermal processing technology in the food industry with a current ever-growing implementation, and meat products represent about a quarter of the HPP foods. The intensive research conducted in the last decades has described the molecular impacts of HPP on microorganisms and endogenous meat components such as structural proteins, enzyme activities, myoglobin and meat color chemistry, and lipids, resulting in the characterization of the mechanisms responsible for most of the texture, color, and oxidative changes observed when meat is submitted to HPP. These molecular mechanisms with major effect on the safety and quality of muscle foods are comprehensively reviewed. The understanding of the high pressure-induced molecular impacts has permitted a directed use of the HPP technology, and nowadays, HPP is applied as a cold pasteurization method to inactive vegetative spoilage and pathogenic microorganisms in ready-to-eat cold cuts and to extend shelf life, allowing the reduction of food waste and the gain of market boundaries in a globalized economy. Yet, other applications of HPP have been explored in detail, namely, its use for meat tenderization and for structure formation in the manufacturing of processed meats, though these two practices have scarcely been taken up by industry. This review condenses the most pertinent-related knowledge that can unlock the utilization of these two mainstream transformation processes of meat and facilitate the development of healthier clean label processed meats and a rapid method for achieving sous vide tenderness. Finally, scientific and technological challenges still to be overcome are discussed in order to leverage the development of innovative applications using HPP technology for the future meat industry.

Formation and Inhibition of Lipid Alkyl Radicals in Roasted Meat

Free radicals are ubiquitous in roasted foods. In this work, lipid-derived carbon-centered alkyl radical formation was first studied in roasted meat by electron spin resonance (ESR). The influence of antioxidants on the inhibition of free radicals was investigated. The results showed that the high temperature, high heat transfer rate, and high polyunsaturated fatty acid (PUFA) content resulted in high radical content in roasted meat, while the high water content in meat retarded radical formation. The 0.03% addition of tea polyphenols (TPP) significantly reduced radical formation during roasting (p < 0.05), whereas the 0.03% rosemary extract (RE) had no significant inhibitory effect (p > 0.05). These results suggested that water retention and the addition of TPP would decrease radical generation during the roasting of meat.

Microstructure, microbial profile and quality characteristics of high-pressure-treated chicken nuggets

High-pressure processing (300 MPa for 5 min) as a non-thermal post-processing intervention was employed to improve the shelf life and qualities of cooked refrigerated chicken nuggets. Pomegranate peel extract (1%) was also used as a source of natural antioxidant and antimicrobial in chicken nuggets. Microstructure, microbial profile, instrumental colour, texture profile and lipid oxidation were evaluated. High-pressure treatment and pomegranate peel extract did not influence significantly the colour and textural properties of cooked chicken nuggets. Thiobarbituric acid reactive substance values significantly (p < 0.05) increased in pressure-treated nuggets. Microstructural studies revealed shrinkage in the structure and loosening of the dense network of meat emulsion due to high-pressure treatment. Pressure treatment resulted in a reduction of 2-3.0 log10 cfu/g in total plate count and Enterobacteriaceae count. Molecular characterization studies revealed that Enterobacter amnigenus and Enterobacter sp. in control and Bacillus licheniformis, Enterococcus gallinarum and Acinetobacter baumannii in high-pressure-treated chicken nuggets were the major spoilage bacteria.

Synthesis and evaluation of antioxidant and antibacterial behavior of CuO nanoparticles

CuO nanoparticles were synthesized by thermal decomposition methods and characterized by UV-visible spectroscopy, XRD and TEM analysis. The resultant particles are nearly spherical and particle size is in the range of 15-30 nm. The antioxidant behavior of synthesized CuO nanoparticles was evaluated by scavenging free radicals of 2,2-diphenyl-1-picrylhydrazyl hydrate (DPPH). The free radical scavenging activity of CuO nanoparticles was monitored by UV-visible spectrophotometry. The antibacterial activity of CuO nanoparticles was tested against different bacterial strains. CuO nanoparticles showed efficient antioxidant activity and bactericidal effect against Eschericia coli and Pseudomonas aeruginosa.

Effect of antioxidant on the fatty acid composition and lipid oxidation of intramuscular lipid in pressurized pork

To investigate the effect of antioxidants on lipid oxidation and fatty acid composition in pressurized pork, minced pork with or without 1% Na(2)EDTA was pressurized at 500MPa before 7days storage at 4°C. TBARS value, lipid content and fatty acid composition in untreated and high-pressure (HP) treated samples were analyzed. HP treatment induced marked increases in TBARS values and lipolysis of partial phospholipids causing an increase of free fatty acid content. Preferential hydrolysis for polyunsaturated fatty acids (PUFA) in phospholipids resulted in the percentage of PUFA in phospholipids decreasing markedly and thereby that in free fatty acids increasing significantly. Addition of 1% Na(2)EDTA to minced pork before HP significantly decreased the TBARS values in pressurized samples, but did not inhibit the lipolysis of phospholipids, causing the fatty acid composition of phospholipids and free fatty acids to change similarly to those samples without Na(2)EDTA.

Effect of high-pressure treatment on the fatty acid composition of intramuscular lipid in pork

To investigate the effect of high-pressure (HP) treatment on lipid oxidation and fatty acid composition of intramuscular lipid in pork, the longissimus muscles from Rongchang (RC) pig were pressurized at 200, 350 and 500 MPa for 20 min at 20°C prior to 7 days storage at 4°C. The changes in TBARS number, lipid content and fatty acid composition of total intramuscular lipids, phospholipids, triglycerides and free fatty acids in untreated and HP treated samples were analyzed. HP treatment had no significant effect on the content and fatty acid composition of total lipids and triglycerides in the samples, but treatment at 350 MPa and above led to marked increases in TBARS values and lipolysis of partial phospholipids causing a correlative increase of free fatty acid content. A preferential hydrolysis for polyunsaturated fatty acids (PUFA) in phospholipids was observed, which resulted in the percentage of PUFA in phospholipids decreasing markedly and thereby that in free fatty acids increasing significantly.

Aroma development in high pressure treated beef and chicken meat compared to raw and heat treated

Chicken breast and beef muscle were treated at 400 and 600 MPa for 15 min at 5 degrees C and compared to raw meat and a heated sample (100 degrees C for 15 min). Vacuum-packed beef meat with a smaller fraction of unsaturated fatty acids showed better oxidative stability during 14 days of cold storage, as shown by a low steady-state level of hydroperoxide values, than vacuum-packed chicken meat. Accordingly, the critical pressures of 400 MPa and 600 MPa for chicken breast and beef sirloin, respectively, were established. Volatiles released after opening of the meat bags or during storage of open meat bags, simulating consumer behaviour, were measured under conditions mimicking eating. Quantitative and olfactory analysis of pressurised meat gave a total of 46 flavour volatiles, mainly alcohols (11), aldehydes (15), and ketones (11), but all in low abundance after 14 days of storage. Overall, beef meat contained less volatiles and in lower abundance (factor of 5) compared to chicken meat. The most important odour active volatiles (GC-O) were well below the detection thresholds necessary to impart a perceivable off-flavour. Lipid oxidation was significantly accelerated during 24h of cold storage in both cooked chicken and beef when exposed to oxygen, while the pressurised and oxygen-exposed chicken and beef meat remained stable. Pressure treatment of beef and chicken did not induce severe changes of their raw aroma profiles.

Enriching M. sternomandibularis with alpha-tocopherol by dietary means does not protect against the lipid oxidation caused by high-pressure processing

We hypothesized that elevating the concentration of alpha-tocopherol in beef muscle tissue by dietary means would increase lipid stability following high-pressure processing. Beef M. sternomandibularis was obtained from cattle that had medium (4.92 microg/g) and high (7.30 microg/g) concentrations of alpha-tocopherol. Post-rigor, paired muscles samples were subjected to pressures of 0.1 (atmospheric), 200 or 800 MPa for 20 min at approximately 60 degrees C. Following high-pressure processing, measurements were made immediately (d 0) or on samples stored in the dark for 6 d at 4 degrees C (d 6). Intramuscular lipid was similar for each group (4.02% vs. 4.26%, respectively; P=0.78), but lipid from the medium alpha-tocopherol muscle was more saturated and less monounsaturated than muscle from the high alpha-tocopherol group. High-pressure processing at 800 MPa and 60 degrees C did not reduce the amount of alpha-tocopherol but significantly reduced the concentration of linoleic acid (18:2n-6) in muscle from both production groups of cattle. Thiobarbituric acid reactive substances increased linearly with treatment pressure only in d 6 samples (day x pressure interaction P=0.0001) and were higher overall (P=0.02) in the high alpha-tocopherol muscle than in the medium alpha-tocopherol muscle. At d 6, lipid peroxides were decreased (P=0.007) by high-pressure treatment and were higher (P<0.0001) in the high alpha-tocopherol group than in the medium alpha-tocopherol group. Therefore, muscle from the high alpha-tocopherol cattle in this study had a greater accumulation of lipid peroxides by d 6, making the muscle from those cattle more susceptible to oxidation.

Evaluation of the ability of antioxidants to counteract lipid oxidation: Existing methods, new trends and challenges

Oxidative degradation of lipids, especially that induced by reactive oxygen species (ROS), leads to quality deterioration of foods and cosmetics and could have harmful effects on health. Currently, a very promising way to overcome this is to use vegetable antioxidants for nutritional, therapeutic or food quality preservation purposes. A major challenge is to develop tools to assess the antioxidant capacity and real efficacy of these molecules. Many rapid in vitro tests are now available, but they are often performed in dissimilar conditions and different properties are thus frequently measured. The so-called 'direct' methods, which use oxidizable substrates, seem to be the only ones capable of measuring real antioxidant power. Some oxidizable substrates correspond to molecules or natural extracts exhibiting biological activity, such as lipids, proteins or nucleic acids, while others are model substrates that are not encountered in biological systems or foods. Only lipid oxidation and direct methods using lipid-like substrates will be discussed in this review. The main mechanisms of autoxidation and antioxidation are recapitulated, then the four components of a standard test (oxidizable substrate, medium, oxidation conditions and antioxidant) applied to a single antioxidant or complex mixtures are dealt with successively. The study is focused particularly on model lipids, but also on dietary and biological lipids isolated from their natural environment, including lipoproteins and phospholipidic membranes. Then the advantages and drawbacks of existing methods and new approaches are compared according to the context. Finally, recent trends based on the chemometric strategy are introduced as a highly promising prospect for harmonizing in vitro methods.