Lipid Oxidation In Meat Research Articles

Production and Characterization of Antioxidative Hydrolysates and Peptides from Corn Gluten Meal Using Papain, Ficin, and Bromelain.

There has been a growing interest in developing natural antioxidants with high efficiency and low cost. Bioactive protein hydrolysates could be a potential source of natural and safer antioxidants. The objectives of this study were to hydrolyze corn gluten meal using three plant-derived proteases, namely papain, ficin, and bromelain, to produce antioxidative hydrolysates and peptides and to characterize the antioxidant performances using both chemical assays and a ground meat model. The optimum hydrolysis time for papain was 3 h, and for ficin and bromelain was 4 h. The hydrolysates were further separated by sequential ultrafiltration to 5 hydrolysate fractions named F1 to F5 from low molecular weight (MW) (<1 kDa) to high MW range (>10 kDa), which were further characterized for TPC, free radical scavenging capacity against DPPH and ABTS, and metal chelating activity. The fraction F4 produced by papain (CH-P4), F1 produced by ficin (CH-F1), and F3 produced by bromelain (CH-B3) showed the strongest antioxidant activity and yield, respectively. These three fractions were incorporated into ground pork to determine their inhibition effects on lipid oxidation during a 16-day storage period. The inhibition effect was enhanced with the addition of higher amount of hydrolysate (e.g., 1000 vs. 500 mg/kg). The CH-P4 reduced lipid oxidation in ground meat by as much as 30.45%, and CH-B3 reduced oxidation by 27.2% at the same level, but the inhibition was only 13.83% with 1000 mg/kg of CH-F1. The study demonstrated that CGM protein hydrolysates and peptides could be used as naturally derived antioxidant in retarding lipid oxidation and improving product storage stability.

The effects of Myristica fragrans seed meal and Syzygium aromaticum leaf meal dietary supplementation on growth performance and oxidative status of broiler chicken

BackgroundThe study examined the effects of Myristica fragrans seed meal (MSM) and Syzygium aromaticum leaf meal (SLM) dietary supplementation on the growth performance, health status, and meat quality of broiler chicken.MethodsA total of two hundred and forty 1-day-old broiler chickens were assigned the four dietary treatments: Diet 1/control (no supplementation), Diet 2 (0.25% MSM), Diet 3 (0.25% SLM), and Diet 4 (0.25% MSCM, i.e., MSM + SLM 1:1). The birds were fed ad libitum throughout the feeding trial.ResultsThe dietary supplementation of 0.25% MSCM resulted in higher body weight gain and lowered feed conversion ratio (p < 0.05) at the finisher stage and overall period, while feed intake was not statistically affected (p > 0.05) across the treatments. The dietary inclusion of MSM, SLM, and MSCM did not significantly influence carcass traits, relative internal organ weights, and haematological indices of the broiler chicken (p > 0.05) except mean cell volume and mean cell haemoglobin content (p < 0.05). The result further revealed that broilers fed diets supplemented with MSM, SLM, and MSCM had higher (p < 0.05) serum catalase, glutathione peroxidase and lowered serum cholesterol compared with control. The meat cholesterol levels and lipid peroxidation of the birds were significantly (p < 0.05) reduced, while glutathione peroxidase was increased by dietary MSM, and MSCM supplementation.ConclusionThe MSCM supplementation at 0.25% enhanced the body weight gain, improved serum, and meat glutathione peroxidase and catalase but reduced the broiler’s meat cholesterol level and lipid oxidation.

The Impact of Antioxidant Supplementation and Heat Stress on Carcass Characteristics, Muscle Nutritional Profile and Functionality of Lamb Meat.

The impact of antioxidant supplementation and short-term heat stress on lamb body weight gain, meat nutritional profile and functionality (storage stability of lipids and colour) of lamb meat was investigated. A total of 48 crossbred ((Merino × Border Leicester) × Dorset) lambs (42 ± 2 kg body weight, 7 mo age) were randomly allocated to three dietary treatments (n = 16) by liveweight (LW) that differed in dosage of vitamin E and selenium (Se) in the diet. Vitamin E and Se levels in the control (CON), moderate (MOD) and supranutritional (SUP) dietary treatments were 28, 130 and 228 mg/kg DM as α-tocopherol acetate and 0.16, 0.66 and 1.16 mg Se as SelPlex™/kg DM, respectively. After four weeks of feeding in individual pens, including one week of adaptation, lambs were exposed to two heat treatments. Animals were moved to metabolism cages for one week and subjected to heat treatments: thermoneutral (TN; 18-21 °C and 40-50% relative humidity) and heat stress (HS; 28-40 °C and 30-40% relative humidity) conditions, respectively. Final LW and hot carcass weight were influenced by dietary treatments with higher final live weight (FLW) (p = 0.05; 46.8 vs. 44.4 and 43.8 kg, respectively) and hot carcass weight (HCW) (p = 0.01; 22.5 vs. 21.3 and 21.0 kg, respectively) recorded in lambs fed the SUP as opposed to the CON and MOD diets. Vitamin E concentration in the longissimus lumborum (LL) muscle tended to be higher in lambs fed MOD or SUP diets than the CON group. Lipid oxidation of aged meat at 72 h of simulated retail display was reduced by antioxidant supplementation. Short-term (one week) heat stress treatment significantly increased muscle linoleic acid and total omega-6 concentrations compared with the CON group. The results demonstrate that four-week antioxidant supplementation at the SUP level improved animal productivity by increasing LW and carcass weight and the functionality of meat exhibited by reduced lipid oxidation. An increase in muscle omega-6 fatty acid concentration from short-term heat stress may induce oxidative stress via proinflammatory action.

Meat Composition, Fatty Acid Profile and Sensory Attributes of Meat from Goats Fed Diet Supplemented with Fermented Saccharina japonica and Dendropanax morbifera

A 90-day feeding trial was conducted to evaluate the effects of diets supplemented with three concentrations (control or 0%, 0.5% and 1.0%) of fermented Saccharina japonica and Dendropanax morbifera (FSJ-DM) on the meat composition, growth performance, oxidative stability and fatty acid profile of Korean native black goat (KNBG) meat. The feed conversion ratio and body weight gain (1st to 2nd month) were improved significantly (p < 0.05) in response to feed supplemented with 1.0% FSJ-DM. Moisture content was increased, whereas ether extract and cholesterol contents were decreased in meat obtained from goats supplemented with 1.0% FSJ-DM dietary feeds (p < 0.05). In the same diet group, the total saturated fatty acids (ΣSFA) were lower, whereas the sum of polyunsaturated fatty acids (ΣPUFA) was higher, along with higher PUFA/SFA ratio and lower n-6/n-3 ratio (p < 0.05). On an average, the dietary supplementation of 1.0% FSJ-DM reduced the thiobarbituric acid reactive substance (TBARS) and pH values of goat meat. Overall, the results of this study suggest that diet supplemented with 1.0% FSJ-DM improves the meat composition, growth performance and fatty acid profile and reduces lipid oxidation of goat meat.

The efficiency of stabilizing the oxidative spoilage of meat-containing products with a balanced fat-acid composition

This paper reports a study of the fatty acid composition of a meat-containing semi-smoked sausage with Peking duck meat that established the biological effectiveness of the product's fat. The rosemary extract application efficiency has been investigated for the course of oxidation processes in a semi-smoked sausage with a high content of unsaturated fatty acids. The high content of the monounsaturated FA C18:1 ω-9 (oleic) has been determined experimentally, 40.37 g/100 g fat. The content of the PUFA ω-3 in a meat-containing semi-smoked sausage made from the meat of Peking duck is 1.22 g/100 g of fat, which satisfies the daily recommended need in essential FA by 27 %. The ratio between the families of the FA w-3/w-6 in the developed products is at least 1:11 at the recommended physiological norms of the perfect fat composition in a meat product of 1:10. The current study has confirmed the high antioxidant activity of rosemary extract and the effective inhibition of the process of lipid oxidation in meat-containing sausages. Introducing a rosemary extract in the amount of 0.02–0.06 % slows down the hydrolytic oxidation of minced meat lipids by 29.13–35.00 %, inhibits the peroxidation of lipids in the meat-containing semi-smoked sausage, thereby reducing the number of peroxides by almost five times. It has been confirmed that stabilizing the peroxidation of lipids in the meat-containing semi-smoked sausage made from Peking duck meat with a high concentration of unsaturated fatty acids should, as a consequence, reduce the concentration of secondary oxidation products. The number of aldehydes and ketones was least at the end of shelf-life of the finished products and was 0.38–0.80 mg MA/kg of the product, which is 2.54–3.94 times lower than that of control sample. The greatest stabilizing effect has been achieved when introducing a rosemary extract in the amount of 0.06 %, which makes it possible to reduce the indicators of oxidative spoilage of fat by more than twice.

Cobalt‐60 and electron beam irradiation‐induced lipid oxidation in largemouth bass (Micropterus salmoides)

Irradiation can cause lipid oxidation of fish. This study aimed to examine the effect of radiation (method, dose and dose rate) on the acid value (AV), peroxide value (PV), thiobarbituric acid reactive substances (TBARS) content and fatty acid profile of fresh and freeze-dried largemouth bass flesh. AV, PV and TBARS presented a dose-dependent increase in fish meat for both cobalt-60 (60 Co) and electron beam (EB) irradiation. With a 6 kGy dose of radiation, all measured indices in the 60 Co group were significantly higher than those in the EB group (P < 0.05 or P < 0.01). With a 3 kGy dose of radiation, AV, PV and TBARS in the 200 Gy min-1 dose rate group were significantly lower than those in the 2 and 80 Gy min-1 groups (P < 0.05). After 60 Co irradiation, AV, PV and TBARS in most fresh samples were significantly higher than those in freeze-dried samples (P < 0.01). And 60 Co irradiation decreased the unsaturated fatty acid (UFA) content in fresh samples and increased the UFA content in freeze-dried samples. Our study indicated that 60 Co irradiation, particularly at a low dose rate, accelerated lipid oxidation in fish meat. A large amount of muscle moisture enhances the amount of UFA loss in fish meat during 60 Co irradiation. A low dose (3 kGy) of EB irradiation, a high dose rate (200 Gy min-1 ) of 60 Co irradiation or freeze-drying treatment can alleviate the lipid oxidation of largemouth bass meat. © 2020 Society of Chemical Industry.

Fatty acid profile analysis of grape by-products from Slovakia and Austria

Fatty acid profile analysis of grape by-products from Slovakia and Austria

Supplementation with free methionine or methionine dipeptide improves meat quality in broilers exposed to heat stress.

This study aimed to evaluate the effect of methionine dipeptide supplementation on the meat quality of broilers subjected to heat stress. A completely randomized 3 × 2 factorial design with four repetitions of each treatment was used. Three diets, unsupplemented (U), supplemented with methionine (M), and supplemented with methionine dipeptide (MM), were fed to 96 broilers subjected to thermal comfort (TC) or heat stress (HS, 32°C for 24h) conditions antemortem. Meat quality parameters, total antioxidant capacity (TAC), protein and lipid oxidation, and ryanodine receptor type 3 (RYR3) gene expression in breast muscle of 35-day-old broilers were evaluated. Methionine supplementation (M and MM) enhanced the nutritional quality of breast meat. Diet had a significant effect on breast meat pH, color (a*), and nitrogen and lipid contents. Interaction effects of diet and HS on TAC and protein oxidation were not observed. Diet and HS influenced lipid oxidation of breast meat after 7days of refrigerated storage. High RYR3 expression was observed in breast meat of broilers subjected to heat stress and fed the U diet. No differences were observed between M and MM diets in any of the parameters evaluated. The results showed that both sources of methionine (M and MM) can be supplemented in broiler diets with beneficial effects on breast yield and meat nutritional quality. In addition, HS has made chickens more susceptible to biomolecule oxidation, and MM can potentiate chicken TAC. Further study is needed to better understand the effects of MM on broilers.

Effect of Gelatin Coating Enriched with Antioxidant Tomato By-Products on the Quality of Pork Meat.

The use of edible biopolymers and natural additives obtained from food processing by-products is a sustainable strategy for food packaging applications. Gelatin is a biopolymer with great potential as a coating due to its low cost, high availability, and technological and functional properties. Among them, gelatin can be used as a carrier of bioactive compounds such as antioxidants, which can retard oxidation processes and thus extend the shelf-life of highly-perishable products. This study evaluated the effect of gelatin coating enriched with antioxidant tomato by-products hydrolysate (TBPH) on the quality of pork meat during cold storage. Results showed that TBPH obtained from Alcalase hydrolysis presented antioxidant activity with good stability against cooking. Additionally, chromatographic and mass spectrometry techniques, as well as in silico analysis, were used for the peptidomic characterisation of TBPH. The application of enriched gelatin coating on meat led to some physicochemical changes including increased weight loss and colour differences; however, the pH and water activity, which control meat spoilage, were maintained during storage. Moreover, coating prevented lipid oxidation of meat, and enriched-coated meat presented high antioxidant activity after cooking. These results suggest the positive role of gelatin coating enriched with TBPH in extending the shelf-life of meat during storage.

Influence of Grape Pomace Intake on Nutritional Value, Lipid Oxidation and Volatile Profile of Poultry Meat.

Grape pomace (GP) represents the main solid by-product deriving from grape processing. The aim of this study was to evaluate the effect of dietary GP intake on nutritional quality, lipid oxidation and volatile profile of chicken meat. A total of 112 Ross 508 broilers were randomly divided into 4 groups and fed for 21 days with a standard diet. For the remaining 28 days of the trial, the control group (CG) continued to receive a standard diet, while the experimental groups (EGs) were fed with diets containing different GP concentrations: 2.5% (EG1), 5% (EG2) and 7% (EG3). Following the slaughtering, samples of breast meat were collected from each group. No significant differences were observed for pH, cooking loss and meat brightness, whereas the GP intake showed effectiveness in inducing variations in drip loss, meat yellowness and redness. The experimental feeding strategy also induced changes in the fatty acid profile, with an overall increase in polyunsaturated fatty acids (PUFA), mainly due to the increase in concentration of linoleic acid. The dietary supplementation also induced a decrease in lipid oxidation in meat, a finding also confirmed by the reduction in volatile aldehydes in 7 days stored raw meat. The feeding strategy based on the use of GP did not induce detrimental effects on the quality of broiler meat and showed the potential to lengthen the shelf-life as a direct consequence of the improvement in the oxidative stability. Overall, the present study showed a viable way for the recovery and the valorization of an agro-industrial by-product, with potential benefits also from an environmental point of view.

Influence of feeding systems on Chemical Contents and Sensory Quality of Longissimus thoracis Lamb Muscle cooked in boil and grill

Nutritive and sensory characteristics of the lamb meat depend not only on breeding conditions and systems but also on cooking procedures. The aim of this study was to evaluate the effect of two cooking methods on the nutri-tional and sensory quality of L. thoracis meat from lambs reared in two Alge-rian systems. The lambs grazed either in a highland pasture with a hay sup-plementation, or in a steppe pasture with concentrate supplemention. After three months of grazing, all the lambs from both rearing systems were slaughtered, and eviscerated in a local commercial slaughterhouse. The dis-sected muscles were trimmed, minced in a meat grinder and analysed. Grill-ing and broth cooking were respectively performed at 250°C and 100°C for 30 min. The obtained results indicated that cooking methods had a signifi-cant effect (p &lt;0.05) on all the analyzed parameters. It appeared that fat, water loss and thiobarbituric acid reactive substances (TBARS) values of the samples increased with cooking procedure. Overall, cooking increased total saturated and polyunsaturated fatty acid contents of the intramuscular lipid (p&lt;0.05) while reducing the n-6/n-3 ratio (p&lt;0.001). The results reported on the color analysis indicated significant difference for the red index (p&lt;0.05) which was more predominant in the Steppe fed lamb muscle than in the highland one (14.05 vs. 8.01, respectively). Changes in a* values appeared to be affected by lipid oxidation and are strongly correlated with thiobarbituric acid reactive substances (TBARS) values. Finally, although cooking results in an increase in the lipid oxidation of meat, its nutritional and dietary value is not impaired. It seems that the Algerian rearing systems is an interesting for outdoor sheep breeding and allow to obtain a meat preserving a healthy nutritional quality after cooking.

Ruminal fermentation, microbial population and lipid metabolism in gastrointestinal nematode-infected lambs fed a diet supplemented with herbal mixtures.

The aim of this study was to evaluate the effects of medicinal herbal mixtures rich in phenolic, flavonoid and alkaloid compounds on ruminal fermentation and microbial populations, and fatty acid (FA) concentrations and lipid oxidation in tissues of lambs infected with the gastrointestinal nematode (GIN) parasite (Haemonchus contortus). Parallel in vitro and in vivo studies were performed using two different herbal mixtures (Mix1 and Mix2). The in vitro study was conducted in a 2 (infection status; non-infected versus infected) × 3 (diets; control, Mix1 and Mix2) factorial design. In the in vivo study, 24 lambs were equally divided into four treatments: non-infected lambs fed a control diet, infected lambs fed the control diet, infected lambs fed a diet with Mix1 and infected lambs fed a diet with Mix2. Herbal mixtures (100 g dry matter (DM)/d) were added to the basal diets of meadow hay (ad libitum) and a commercial concentrate (500 g DM/d). The experimental period lasted for 70 days. Ruminal fermentation characteristics and methane production were not affected by infection in vivo or in vitro. Both herbal mixture supplementation increased total volatile fatty acid (VFA) concentrations (P < 0.01) and DM digestibility (P < 0.01) in vitro. Archaea population was slightly diminished by both herbal mixtures (P < 0.05), but they did not lower methane production in vitro or in vivo (P > 0.05). Infection of H. contortus or herbal mixtures modulated FA proportion mainly in the liver, especially the long chain FA proportion. Concentrations of thiobarbituric acid reactive substances (TBARS) in serum were significantly higher after 70 days post-infection in the infected lambs. Herbal Mix1 supplementation reduced TBARS concentrations in meat after seven days of storage. In conclusion, supplementing of herbal mixtures to the diets of GIN parasite infected lambs did not affect the basic ruminal fermentation parameters. Herbal mixtures may improve few FA proportions mainly in liver as well as decrease lipid oxidation in meat.

Eco-friendly active packaging consisting of nanostructured biopolymer matrix reinforced with TiO2 and essential oil: Application for preservation of refrigerated meat

Biodegradable active packaging is required to replace petroleum-based plastics. In this study, a biopolymer-based packaging material was prepared using a casting method, which consisted of a cellulose nanofiber/whey protein matrix containing titanium dioxide particles (1% TiO2) and essential oil droplets (2% rosemary oil) as functional components. The ability of this packaging to protect lamb meat from chemical and microbial spoilage during 15 days of refrigerated storage (4 °C) was analysed. The meat samples were periodically analysed for microbial count, chemical stability (pH, lipid oxidation, lipolysis), and optical properties. The active packaging significantly reduced microbial growth, lipid oxidation, and lipolysis of the lamb meat during storage, which led to an increase in shelf life from around 6 to 15 days. These biopolymer-based active packaging materials may therefore be suitable for application in meat products.

Comprehensive account on role of catechin based polyphenols in nanocomposite formulations

Antioxidants play a crucial role in wellness, health maintenance and the prevention of chronic and degenerative disease, in neuroprotection activities and protection against oxidative cellular damage by U.V. radiation. Polyphenols are secondary metabolites of plants usually involved in defense against ultraviolet radiation or aggression by pathogens. Antioxidant properties, free radical-scavenging abilities and antimicrobial properties of these polyphenols make them useful in the field of biomedical applications, used as food additives, as bio preservatives to improve the shelf life of perishable products. Polyphenols are progressively gaining popularity due their wide spectrum of biological activities when taken as a dietary input or as supplements. They are also used as antidiarrheal, antiulcer, anti-inflammatory as well as treatment of diseases such as hypertension, vascular fragility, and allergies. Catechins are easily available and extractable polyphenol which possess excellent antioxidant properties and are also able to inhibit lipid oxidation in red meat, poultry and fish .Present study is an insight to the unique properties and applications of Catechins derived from Acacia catechu. Present study is a brief account on catechin based nanocomposites for advanced applications.

Extending the Shelf Life of Ready-to-Eat Spiced Chicken Meat: Garlic Aqueous Extracts-Carboxymethyl Chitosan Ultrasonicated Coating Solution

Edible crude nano-coating solutions were prepared via ultrasonic treatment using carboxymethyl chitosan (CMCS) and garlic aqueous extracts as raw materials, and these were used to extend the shelf life of ready-to-eat (RTE) spiced chicken meat. First, the chemical composition of garlic aqueous extracts and the properties of the ultrasonicated coating solutions (particle size, ZETA potential, bacteriostasis, and mechanical properties) were determined. The results showed that the main chemical component was diallyl disulfide, and the most suitable coating solution (solution A) was produced by the addition of the garlic aqueous extracts after ultrasonic treatment of the CMCS solution. Subsequently, solution A was applied to the preservation experiment of the RTE chicken meat. According to microbial index (total viable count, TVC) and physical and chemical indicators, including total volatile base nitrogen (TVB-N), thiobarbituric acid reactive substances (TBARS), water distribution, and sensory evaluation, it was determined that this method effectively inhibited the growth of microorganisms and could delay the rate of protein breakdown and lipid oxidation in the RTE chicken meat. Moreover, there were no side effects regarding the appearance or taste of the products. Therefore, the garlic aqueous extracts-CMCS ultrasonicated coating method could be used as a potential fresh-keeping method for RTE chicken meat.

In Vitro Antioxidant Properties of Berry Leaves and Their Inhibitory Effect on Lipid Peroxidation of Thigh Meat from Broiler Chickens

AbstractThe present study is designed to evaluate the antioxidant compounds from bilberry, cranberry, and raspberry leaves in connection with their radical scavenging activities, and their potential in inhibiting the lipid peroxidation of thigh meat from broiler chickens. For this purpose, plant extracts are analyzed regarding the content in bioactive compounds, antioxidant properties analysis including 1,1‐diphenyl‐2‐picrylhydrazyl, superoxide, hydrogen peroxide, and hydroxyl radical‐scavenging activities. Lipid peroxidation is induced by an Fe+3/ascorbic acid system and the inhibitory effects of plants extracts are assessed using thiobarbituric reactive substances (TBARS) as biomarkers for quantifying lipid oxidation in meat. The overview of the analyzed antioxidant compounds shows that cranberry leaves present the highest concentrations of vitamin E, β‐carotene, lutein and zeaxanthin, and polyphenols and a total antioxidant capacity with 52% higher than bilberry and 360% than raspberry. Bilberry leaves extract shows the strongest effect (p &lt; 0.0001) in inhibiting meat lipid peroxidation.Practical Applications: The results demonstrate the positive effect of the selected berry leaves in the oxidative stability of broiler chicken meat under in vitro conditions, and may be suggested as an alternative source of natural antioxidants for animal nutrition, with benefits in inhibiting and delaying oxidation, and also enhancing the nutritional value of meat.

Chromium and arsenic speciation analysis in meats by HPLC-ICP-MS in the presence of hydrolyzed oat proteins with radical scavenging activities

Transition metals play an important role in a wide variety of biological processes, but their functions are dependent on the quantity and the type of species present. Specific forms of arsenic (As) and chromium (Cr) are associated with oxidative stress, cellular damage and inflammation. The aim of this research was to test in a food system whether, in the presence of hydrolyzed oat proteins, arsenic or chromium will exist predominantly in a specific oxidative state, and to evaluate the potential implication of promoting or decreasing oxidative stress. Eight hydrolyzed proteins with different degrees of radical scavenging activities were produced by combining two extraction methods and four proteases. The addition of hydrolysates to ground chicken meat decreased lipid hydroperoxides by up to 50% when stored at 4 °C but had no effect at -20 °C. The ratio of pentavalent arsenic (As(V)) to arsenobetaine (AsB) in meat was about 2:1 but in the presence of the hydrolysates, meanwhile, the amount of AsB detected was 3-fold higher depending on the storage condition. This was due to better extraction of AsB in the presence of hydrolysates rather than to the conversion of other species. Data on chromium showed that Cr(VI) contents decreased from 14.3 ± 0.1 to 6.3 ± 0.5 μg/g while concentrations of Cr(III) increased from 2.8 ± 0. 2 to 8.6 ± 0.7 μg/g. In summary, the addition of hydrolyzed oat proteins to chicken meat enhanced the extraction of AsB, and had little effect on arsenic speciation during storage meanwhile, there was a reduction of Cr(VI) to Cr(III) which was in part due to the relative content of thiol groups. Additionally, there was a reduction of lipid oxidation in meats that contained the oat protein hydrolysates.

Increasing the α-tocopherol content and lipid oxidative stability of meat through dietary Cistus ladanifer L. in lamb fed increasing levels of polyunsaturated fatty acid rich vegetable oils

The aim of this study was to evaluate the effect of the dietary inclusion of Cistus ladanifer L. and vegetable oils on intramuscular fat composition, muscle antioxidant status and lipid oxidative stability, and explore the mechanism by which dietary Cistus ladanifer limits the lipid oxidation. Lambs were assigned 9 diets, corresponding to 3 levels of Cistus ladanifer (50, 100 and 200 g/kg DM) and 3 levels of oil (0, 40 and 80 g/kg DM). Oil supplementation increased highly peroxidizable fatty acid content and the peroxidizability index (P < .05). Muscle phenolic content, reducing ability and radical scavenging ability were not affected by Cistus ladanifer (P > .05). The highest level of Cistus ladanifer enhanced muscle resistance to lipid oxidation (P = .006) and increased α-tocopherol content (P = .005), reducing meat lipid oxidation over 7 days of storage (P < .001). Results showed that Cistus ladanifer has a protective effect against lipid oxidation through increasing α-tocopherol concentration in the muscle.

Lipid oxidation induced by heating in chicken meat and the relationship with oxidants and antioxidant enzymes activities

The aim of the current research was to examine lipid oxidation in chicken meat heated to different temperatures followed by refrigerator storage and the factors contributing to lipid oxidation. It showed that lipid oxidation was significantly promoted when meat was heated up to 70°C and stored for 2 and 4 D as measured by thiobarbituric acid reactive substance. The monounsaturated fatty acids and polyunsaturated fatty acids also decreased significantly (P < 0.05) with the increase of heating temperature. The liberation of nonheme iron and increase of hydroxyl radical were observed in heated chicken meat, and the activities of antioxidant enzymes was decreased considerably at higher temperatures. The changes of these prooxidants and antioxidants might constitute a possible mechanism for the stronger lipid oxidation in heated meat.

Volatile flavor changes responding to heat stress-induced lipid oxidation in duck meat.

The effects of heat stress on lipid oxidation and volatile compounds in duck meat were investigated. To simulate heat stress on ducks, room-temperature was controlled at 25°C, except that a raised temperature of 32°C for 8hr each day was conducted. After stress for 1 and 3weeks, respectively, the birds were euthanized and the breast meat was separated to evaluate the changes of lipid oxidation and volatile flavor compounds. Results showed that heat stress significantly increased the lipoxygenase activity and thiobarbituric acid reactive substances, and reduced the contents of free unsaturated fatty acids in duck meat. A total of 85 volatile flavor compounds were detected by gas chromatography-mass spectrometry. Interestingly, when exposed to heat stress, the volatiles generation in raw duck meat was promoted, which was then inhibited after cooking. These data reveal meat oxidative changes and flavor loss caused by heat stress and provide useful information for potential labels and meat flavor preservation against the negative effects of heat stress.