Effects of dietary soybean oil on lipid and protein oxidation in pork patties during chill storage

The effect of dietary soybean oil on lipid and protein oxidation in low and high fat pork patties made from quadriceps femoris during chill storage in a high oxygen atmosphere packaging (80% O(2)/20% CO(2)) in the dark for 7 days was investigated. Pigs were fed either a standard diet or a diet added 2% soybean oil. After slaughter high fat pork patties were prepared for both feeding regimes by addition of back fat from pigs fed the same diet whereas low fat pork patties were prepared without addition of back fat. The 2% soybean diet increased the amount of unsaturated fat in the pork. Secondary lipid oxidation products determined as thiobarbituric acid reactive substances (TBARS) were found to increase in the pork patties with increased unsaturated fat. Increased unsaturated fat in the pork patties had no effect on protein oxidation determined as free protein thiol content and protein carbonyl content. A small, but significant increase in protein oxidation was found in the high fat pork patties independent on dietary fat. In conclusion, protein oxidation is unaffected by dietary fat in pork patties during chill storage for periods normally used in retail trade, and lipid and protein oxidation are not coupled under these conditions.     

Effect of oxidized dietary lipid and vitamin E on the colour stability of pork chops

The effect of oxidized corn oil and vitamin E (α-tocopheryl acetate) in pig diets on the oxidative stability of muscle lipids and on the surface colour characteristics of fresh and previously frozen pork chops in refrigerated storage was investigated. Lipid oxidation (TBARS values) and surface redness (Hunter 'a' values) were significantly influenced (P < 0·01) by dietary α-tocopheryl acetate levels but not by degree of oxidation of dietary corn oil. Lipid oxidation and colour deterioration during refrigerated storage were greater in previously frozen chops compared to fresh chops. TBARS values were lower and Hunter 'a' values higher in pork chops from pigs fed 100 and 200 mg α-tocopheryl acetate/kg diet compared to pigs fed 10 mg/kg diet after 2, 4, 6 and 8 days of refrigerated storage. Hunter 'a' values were significantly correlated (P < 0·01) with the logarithm of TBARS values. The results suggest that oxidation of myoglobin precedes oxidation of muscle lipids in pork chops stored at 4°C.     

Effects of supranutritional dietary vitamin E levels on subcellular deposition of α-tocopherol in the muscle and on pork quality

The influence of three levels of vitamin E in the diet of pigs on the subcellular deposition of α-tocopherol in the muscle and on selected quality characteristics of pork meat (oxidative stability of lipids, colour, drip loss, microbial growth) was studied. The content of α-tocopherol in adipose tissue and L. dorsi muscle as well as in mitochondrial and microsomal fractions of the muscle significantly increased (P < 0.05) with increasing levels of dietary vitamin E. The differences in the concentrations of α-tocopherol in the subcellular fractions were evident in the enhanced stability of the membranes when exposed to metmyoglobin/hydrogen peroxide. The beneficial effect of dietary vitamin E on the oxidative stability of pork lipids during the storage of pork chops and ground pork was also demonstrated. Even though lipid oxidation increased in all cases during storage, the pork products from the pigs receiving the highest level of vitamin E (200 IU kg^?1 feed) exhibited the smallest increase in thiobarbituric acid reactive substances. In addition, increased colour stability and decreased drip loss were observed on keeping pork chops, which had been previously frozen for three months, at 4°C under fluoresent light for 10 days. The possible effect of α-tocopherol on membrane fluidity in this context is discussed.     

Oxidative stability of pork meat lipids as related to high-oleic sunflower oil and vitamin E diet supplementation and storage conditions

The aim of this research work was to evaluate the oxidative stability of pork meat lipids as related to dietary supplementation with high-oleic sunflower oil (HOSO) and/or α-tocopheryl acetate (VE), as well as the influence of storage conditions. Four different diets (control; HOSO; VE; HOSO+VE), were fed to swines until slaughtering. Meat slices were packed in vessels with transparent shrink film and exposed to white fluorescent light for 3 days at 8 °C. HOSO supplementation increased oleic acid content of pork meat. The highest levels of peroxide value (PV) and cholesterol oxidation products (COPs) were detected in the control group, whereas HOSO-enriched diets displayed the highest thiobarbituric reactive substance (TBARs) content. After storage under light exposure, pork meat slices exhibited a decrease of PV, which resulted in an increasing trend of TBARs and COPs. Feeding enrichment with both HOSO and vitamin E can be, therefore, used as an appropriate supplementation strategy to produce pork meat with a suitable oxidative stability.     

Use of carbon monoxide combined with carbon dioxide for modified atmosphere packaging of pre- and postrigor fresh pork sausage to improve shelf life

Fresh pre- and postrigor pork sausage patties were manufactured in the Iowa State University Meat Laboratory and packaged either in modified atmosphere (MAP) with 0.4% carbon monoxide (CO) and 99.6% carbon dioxide (CO2) or on foam trays overwrapped with oxygen-permeable film (OW). Packages were stored at 2 to 40C under fluorescent lights for up to 31 days. Aerobic, anaerobic, and psychrotrophic plate counts, raw and cooked color, purge, and lipid oxidation were measured during storage. Results indicated that both pork sausage products in MAP had lower aerobic and psychrotrophic counts and less lipid oxidation throughout storage (P < 0.05). Raw color of both products in MAP was redder than the OW patties (P < 0.05), but the prerigor pork sausage in MAP benefited more from the CO atmosphere in terms of raw color than the postrigor pork sausage in MAP. Cooked color of the prerigor pork sausage in MAP was significantly redder than cooked color of the postrigor pork sausage. Both pork sausage products in MAP were also lighter (L* value) than the OW patties for raw and cooked color. Therefore, the combination of CO and CO2 in MAP was beneficial in extending the shelf life of pre-and postrigor fresh pork sausage by reducing aerobic and psychrotrophic microbial growth and improving oxidative stability and color, compared to conventional OW packaging. However, increased purge, increased anaerobic growth, and changes in cooking behavior were also observed for the products in MAP during storage (P < 0.05).     

LIPID OXIDATION AND SENSORY CHARACTERISTICS OF FRESH AND CURED SAUSAGES FROM α-LINOLENIC ACID ENRICHED PORK

Forty-eight female piglets were raised with four levels of α-linolenic acid (0, 1.5, 2.5, 3.5%) to determine the effect of dietary fat on the fatty acid composition, sensory and storage stability of pork products. The degree of polyunsaturation in neutral lipids and phospholipids were increased significantly by the dietary LNA. The thiobarbituric acid reactive substances (TBARS) vaues of freshly prepared breakfast sausages with vacuum packaging remained low, but those of the loosely packaged, i. e., nonvacuumized, sausages increased more than 3 times during the 48 h storage period. The TBARS values of breakfast sausages frozen-stored for 3 months showed extensive lipid oxidation. The dietary LNA treatments and packaging had significant effects on the susceptibility of breakfast sausages to lipid oxidation. However, the oxidative stability of cured products was not affected by the dietary treatments. The results indicated that the pork enriched with polyunsaturated fatty acids could be used in cured products or uncured meat products protected by ‘hot vacuum packaging’without any sensory or quality deterioration due to lipid oxidation.     

石榴皮提取物与焦磷酸钠复配对猪肉饼品质的影响

为探究焦磷酸钠(sodium pyrophosphate,TSPP)、异抗坏血酸钠(sodium D-isoascorbate,D-V CNa)与石榴皮提取物(pomegranate peel extract,PPE)复配使用在肉制品中是否具有协同增效作用,以丁基羟基茴香醚(butyl hydroyanisole,BHA)为阳性对照,通过对冷藏期间猪肉饼的pH、蒸煮损失、色差、质构特性、脂肪氧化(硫代巴比妥酸值)和蛋白氧化(总巯基、蛋白羰基含量)的表征,研究各抗氧化剂单独或复配使用对猪肉饼品质及贮藏氧化稳定性的影响。结果表明,TSPP可以提高猪肉饼的pH,而D-V CNa与PPE的添加对肉饼的pH无显著影响;TSPP的添加可以降低猪肉饼的蒸煮损失,改善肉饼的质构特性,且效果优于PPE、BHA。冷藏过程中肉饼不断发生脂肪和蛋白氧化,其中TSPP对脂肪氧化的抑制效果与BHA相近,但对蛋白氧化无显著抑制效果;PPE具有良好的抗氧化性能,可以明显抑制猪肉饼的脂肪氧化和蛋白羰基的生成,且在冷藏前期可以抑制巯基向二硫键的转化。整体来看,PPE+TSPP及PPE+TSPP+D-V CNa组合在改善肉饼品质及氧化稳定性方面综合效果最好。     

Addition of Antioxidant to Improve Quality and Sensory Characteristics of Irradiated Pork Patties

The effects of added antioxidants on the oxidative quality changes of irradiated pork patties were studied. Lipid oxidation (TBARS) was not a concern, even in aerobically packaged irradiated pork patties when antioxidants were added. Irradiation produced sulfur compounds, such as dimethyl sulfide and dimethyl disulfide, responsible for irradiation off‐odor. The addition of gallate + tocopherol or sesamol + tocopherol was effective in reducing the sulfur volatiles, but had no effect on the redness of irradiated raw pork patties. Aerobic packaging was highly effective in reducing sulfur volatiles and off‐odor from irradiated meat during storage. Antioxidants had little effect on the sensory characteristics and consumer acceptance of irradiated pork, and consumers did not consider the red color of irradiated raw pork as a quality defect.     

Influence of dietary fat and vitamin E supplementation on α-tocopherol levels and fatty acid profiles in chicken muscle membranal fractions and on susceptibility to lipid peroxidation

Broiler chickens were fed a basal feed supplemented with 10% tallow or olive oil and varying levels of vitamin E (20 and 200 mg vitamin E/kg feed). The concentration of α-tocopherol in the membranes of breast and thigh muscles was significantly influenced by the α-tocopherol level in the feed (p < 0.001). Deposition of vitamin E was not influenced by the type of oil in the feed, except in the mitochondrial fraction of breast where the vitamin E concentration was higher in those fed olive oil than in those fed tallow (p < 0.05). Dietary oil influenced the fatty acid composition of the muscle membranal fractions (p < 0.001). The oxidative stability of the membranal fractions tended to increase with increasing concentrations of α-tocopherol in the membranal fractions. In conclusion, the supplementation of vitamin E appeared to enhance the stability of muscle to oxidation. Thus, incorporation of α-tocopherol into the membranes via dietary manipulation helped in stabilizing the membrane-bound lipids.     

Oxidative stability of frozen pork patties: Effect of fluctuating temperature on lipid oxidation

The mobility of solutes in fat from pork belly, in lean pork belly and in lean pork longissimus dorsi, containing 1% NaCl was characterized by the ESR spin probe technique using the nitroxyl spin probes TEMPO and TEMPOL. The mobility of TEMPO in fat increased for temperature above -60 °C and the mobility of TEMPOL in lean meat increased for temperature above -40 °C. Temperatures for studying the effect of fluctuating temperatures during frozen storage of meat were selected based on the ESR characterization of the mobility of solutes. The oxidative stability of pork patties during frozen storage was measured as thiobarbituric acid reactive substances (TBARS), during storage at -10, -23 and -40 °C and with fluctuations between these temperatures, of pork patties made from pork loin (low fat 1.8%) or pork belly (high fat 22.7%). Lower storage temperatures resulted in less lipid oxidation, and temperature fluctuations between -40 and -23 °C and fluctuations between -23 and -10 °C resulted in oxidation intermediate to oxidation in samples stored at constant low or high temperatures of the fluctuation interval. The level of α-tocopherol was unaffected by the extent of oxidation in the frozen samples, an observation which is discussed in relation to differences in molecular mobility between oxygen and α-tocopherol.     

Quality characteristics of pork patties irradiated and stored in different packaging and storage conditions

Patties were made from pork loin, individually vacuum- or aerobic-packaged and stored either at 4 or -40°C. Refrigerated patties were irradiated at 0, 1.5, 3.0 or 4.5 kGy absorbed dose, and frozen ones were irradiated at 0, 2.5, 5.0, or 7.5 kGy. Samples were analyzed for lipid oxidation, volatile production and odor characteristics. Refrigerated samples were analyzed at 0, 1 and 2 weeks, and frozen ones after 0, 1.5 and 3 months of storage. With vacuum packaging, the lipid oxidation (TBARS) of both refrigerated and frozen patties was not influenced by irradiation and storage time except for the patties irradiated and refrigerated at 7.5 kGy. With refrigerated storage, panelists could detect irradiation odor at day 0, but not after 1 week at 4°C. With frozen storage, however, irradiation odor was detected even after 3 months of storage. With aerobic packaging, the TBARS of refrigerated pork patties increased with storage time. The TBARS of pork patties increased as irradiation dose increased at day 0, but the effect disappeared after 1 week at 4°C. Nonirradiated patties were preferred to the irradiated ones at day 0 because of the significant irradiation odor in the irradiated ones, but the off-odor disappeared after 1 week at 4°C. With frozen storage, patties irradiated at 7.5 kGy had higher TBARS than those irradiated at lower doses. Nonirradiated patties had higher preference scores than the irradiated ones for 1.5 months in frozen storage. Sulfur-containing compounds were responsible for most of the irradiation off-odor, but these volatilized quickly during storage under aerobic conditions. Overall, vacuum packaging was better than aerobic packaging for irradiation and subsequent storage of meat because it minimized oxidative changes in patties and produced minimal amounts of volatile compounds that might be responsible for irradiation off-odor during storage.     

丁香精油纳米胶囊对冷藏调理猪肉饼品质的影响

本实验采用离子凝胶法,以壳聚糖为壁材制备丁香精油纳米胶囊,主要研究了丁香精油纳米胶囊的物理特性及其对调理猪肉饼（4±1）℃冷藏期间菌落总数、脂肪氧化、色泽、pH值、高铁肌红蛋白质量分数以及感官品质的影响。结果表明：丁香精油纳米胶囊的平均粒径为254.7?nm,ζ-电势为35.4?mV,多分散指数为0.33;精油的释放曲线呈现初始的快速增加阶段,随后累积释放率缓慢增加,直到108?h才停止释放;丁香精油可以抑制猪肉饼脂质氧化和微生物腐败,但具有较强烈的精油味道且对猪肉饼护色效果不佳,随着冷藏时间的延长,其抗氧化和抗菌活性下降;添加丁香精油纳米胶囊显著抑制了猪肉饼脂质氧化和微生物生长,并使猪肉饼具有较高的红色稳定性,且对猪肉饼冷藏期间的感官指标没有不良影响。结论：丁香精油纳米胶囊可作为新型纳米保鲜剂延长猪肉饼冷藏期间的货架期。     

石榴皮提取物对猪肉饼冷藏过程中脂肪氧化稳定性的影响

选用陕西省优势天然资源产物石榴皮提取物,测定其总酚及总黄酮含量,采用5 种方法对其抗氧化活性进行评价,并研究不同质量浓度石榴皮提取物的添加对猪肉饼冷藏过程中脂肪氧化稳定性的影响。结果表明：石榴皮提取物具有高效的2,2’-联氮双-（3-乙基苯并噻唑林-6-磺酸）二胺盐（2,2’-azinobis-（3-ethylbenzothi azoline-6-sulfonic acid）ammonium salt,ABTS）自由基（ABTS＋·）、?OH和1,1-二苯基-2-三硝基苯肼自由基清除能力以及一定的金属离子（Fe2＋）螯合能力;石榴皮提取物的添加（0.01%、0.05%和0.10%）能明显减缓猪肉饼冷藏过程中的脂肪氧化;总体来说,随着石榴皮提取物添加量的增加,其脂肪氧化抑制效果增强,且添加0.01%石榴皮提取物时的抑制效果与添加0.01%（以脂肪含量为基准）丁基羟基茴香醚相当。     

Omega-3 LC PUFA Contents and Oxidative Stability of Encapsulated Fish Oil Dietary Supplements

The aim of this study was to examine omega-3 LC PUFA content and oxidative stability of fish oil dietary supplements available in Poland. Nineteen brands of fish body oil and fish liver oil capsules were purchased over the counter and analyzed. Oil content, fatty acid composition and peroxide value were determined. The label claims for EPA and DHA for the majority of the products were presented with reasonable accuracy. However, it can be supposed that the oxidative stability of some fish oil products available on the market might not be sufficient to ensure health quality and safety during longer storage.     

Oil-in-water emulsions as a delivery system for n-3 fatty acids in meat products

The oxidative and physical stabilities of oil-in-water emulsions containing n-3 fatty acids (25 wt.% oil, 2.5 wt.% whey protein, pH 3.0 or pH 6.0), and their subsequent incorporation into meat products were investigated. The physical stability of fish oil emulsions was excellent and neither coalescence nor aggregation occurred during storage. Oxidative stability was better at pH 6.0 compared to pH 3.0 likely due to antioxidative continuous phase proteins. Incorporation of fish oil emulsions into pork sausages led to an increase in oxidation compared to sausages without the added fish oil emulsion. Confocal microscopy of pork sausages with fish oil emulsions revealed that droplets had coalesced in the meat matrix over time which may have contributed to the decreased oxidative stability. Results demonstrate that although interfacial engineering of n-3 fatty acids containing oil-in-water emulsions provides physical and oxidative stability of the base-emulsion, their incorporation into complex meat matrices is a non-trivial undertaking and products may incur changes in quality over time.     

Thiol oxidation and protein cross-link formation during chill storage of pork patties added essential oil of oregano,rosemary, or garlic

The effect of two levels (0.05% and 0.4%) of essential oil of rosemary, oregano, or garlic on protein oxidation in pork patties was studied during storage under modified atmosphere (MAP: 70% O₂: 20% CO₂: 10% N₂) or under aerobic conditions (AE) at 4 °C. The oxidative stability of the meat proteins was evaluated as loss of thiols for up to 9 days of storage, and as formation of myosin cross-links analyzed by SDS-PAGE after 12 days of storage. Protein thiols were lost during storage to yield myosin disulfide cross-links. Essential oils of rosemary and oregano were found to retard the loss of thiols otherwise resulting in myosin cross-links. Garlic essential oil, on the contrary, was found to promote protein oxidation, as seen by an extreme loss in thiol groups, and elevated myosin cross-link formation compared to control.     

Microbiological characteristics of pork chops and ground pork from swine fed a high monosaturated fat diet

Twelve percent high-oleic acid sunflower oil (HOSO) was included in a swine diet to increase the ratio of monounsaturated fatty acids to saturated fatty acids in pork chops and ground pork patties. Aerobic plate counts (APCs) of pork chops prepared from animals on control and HOSO diets did not differ (P >0·05) and no specific pattern of differences in the microflora of pork chops or ground pork patties could be attributed to diet. However, after 4 days of refrigerated storage, APCs of ground pork patties from animals fed the HOSO diet were lower (P<0·05) than those of comparable patties prepared from animals fed the control diet.     

Improved oxidative stability of veal lipids and cholesterol through dietary vitamin E supplementation

The influence of dietary vitamin E supplementation on the α-tocopherol content of muscle membranes and on the resultant oxidative stability of veal was investigated. Daily supplementation of veal calves with 500 mg vitamin E in the form of α-tocopherol acetate for 12 weeks after birth increased muscle and membranal α-tocopherol concentrations approximately 6-fold over those of control animals. Oxidative stability of mitochondrial and microsomal lipids was enhanced by dietary supplementation as indicated by the results of an oxidative assay using hydrogen peroxide-activated metmyoglobin as the catalyst of oxidation. Muscle lipid and cholesterol stability was also improved by supplementation.