抗坏血酸棕榈酸酯对玉米油储藏稳定性的影响

采用Rancimat法测定不同抗坏血酸棕榈酸酯（AP）添加量下玉米油的氧化诱导时间,筛选出与添加50 mg/kg特丁基对苯二酚(TBHQ)玉米油氧化诱导时间相近的150 mg/kg AP添加量作为玉米油中AP目标添加量,开展6周玉米油储藏加速试验,每7 d取样检测酸值、过氧化值、回色（红值）、植物甾醇含量和维生素E含量,同时与TBHQ组（添加量50 mg/kg）、充氮组及空白组样品进行比较,分析AP对玉米油储藏稳定性的影响。结果表明：在玉米油储藏过程中,AP组样品与TBHQ组、充氮组样品在酸值、过氧化值、回色（红值）及植物甾醇含量方面无明显差别;但添加AP对玉米油中维生素E的保留作用明显优于添加TBHQ及充氮。     

抗坏血酸及抗坏血酸棕榈酸酯的稳定性研究

研究了光照、温度、pH、氧化剂、抗氧化剂、金属离子、糖类对抗坏血酸（AA）及抗坏血酸棕榈酸酯（AP）稳定性的影响。结果表明：目光、高温、氧化剂、中性及碱性环境都会不同程度地对两者造成损失,其中抗坏血酸棕榈酸酯的稳定性要强于抗坏血酸。维生素E可以有效保护AP。铜离子、铁离子、锰离子会引起AA较大的损失,锰离子对AP稳定性有显著影响。糖类对两者稳定性基本没有影响。     

Moisturizing potentials of ascorbyl palmitate and calcium ascorbate in various topical formulations

The aim of this study was to use two of Vitamin C derivatives, lipophilic ascorbyl palmitate and hydrophilic calcium ascorbate to determine their skin-hydrating effects for the first time. For this purpose, anhydrous cream, gel and w/o emulsion were prepared and applied to the volunteers' inner forearms. A commercial topical preparation containing a known moisturizer, Vitamin E, was also chosen and used for comparison. Moisture contents of the skin were measured by using corneometer.     

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.     

Antioxidative effects of alpha-tocopherol and ascorbyl palmitate on thermal oxidation of canola oil

Canola oil, with and without added alpha-tocopherol and ascorbyl palmitate, was used to deep-fat frying potatoes once per day for 10 day or once per week for 10 weeks. Changes in chemical and physical properties were monitored. Refractive index, free fatty acids and absorbance at 232 and 270 nm increased with frying time. Smoke point, 'L' color index, iodine value and the C18:2/C16:0 ratio in the oil decreased with the frying time. According to smoke point, which shows the time of the oil should be discarded, canola oil without antioxidant (control) can be used safely 8 times daily or 7 times weekly. For canola oil with antioxidant (oil + alpha-tocopherol + ascorbyl palmitate), the smoke point did not decrease below 170 degrees C in both daily and weekly fryings. This showed that canola oil with antioxidant could be used safely at least 10 times for both frying intervals. In both daily and weekly fryings, the addition of 200 ppm alpha-tocopherol and 200 ppm ascorbyl palmitate increased the oxidative stability of canola oil.     

Effect of the dietary supplementation with vitamin E on colour stability and lipid oxidation in packaged, minced pork

The effect of supplementation of vitamin E (200 W kg⁻¹ feed) in the diet of pigs on colour stability and lipid oxidation in minced pork was studied. Control and enriched diets were provided for the last 12 weeks before slaughter. Half of the samples of minced shoulder meat from control and supplemented pigs were packaged on trays with oxygen-permeable overwraps and half in modified atmosphere packs (initial gas mixture: O₂/CO₂/N₂ = 66/ 27/7). Meats were stored for 10 days at 7 °C in an illuminated retail display cabinet. The meat from vitamin E-supplemented pigs was more resistant to lipid oxidation than was the control meat. Gas packaging appeared to increase lipid oxidation in control meat, whereas lipid oxidation was stable in meat from vitamin E-supplemented pigs. Colour stability for gaspacked meat was comparable for both dietary groups. However, oxygen-permeable overwraps had a negative effect on colour stability in vitamin E-enriched meat. The reason for this is not known. The shelf-life of enriched and control meat was similar. Thus supplementation of pig feeds with vitamin E is recommended if an improved stability against lipid oxidation of (minced) pork is required.     

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.     

光照对猪肉脂肪氧化影响的研究

研究了4±0.5℃贮存温度下,避光和光照条件对通脊肉肌内和皮下脂肪氧化程度的影响,同时比较9±1℃贮存温度下,不同光源(日光灯和白炽灯)照射对猪肉肌内脂肪氧化程度的影响。结果表明,无论是避光条件还是光照条件下,肌内脂肪氧化程度均远远大于皮下脂肪的氧化程度(p<0.05)。因此,控制肌内脂肪氧化是保证冷却肉良好品质的关键。光照可以明显加快脂肪氧化速度,并加深氧化程度,且对肌内脂肪氧化程度的加深远大于对皮下脂肪氧化程度的加深,同时研究发现,日光灯照射对脂肪氧化程度的加深远大于白炽灯照射对脂肪氧化程度的影响。     

葡萄籽提取物对发酵猪肉香肠氧化稳定性的影响

以感官品质、酸价、过氧化值和硫代巴比妥酸值为指标,研究葡萄籽提取物对发酵猪肉香肠氧化稳定性的影响。实验结果表明,随着葡萄籽提取物添加量的增加,发酵猪肉香肠的感官品质变化不大,而酸价、过氧化值和硫代巴比妥酸值的变化越来越慢,表明葡萄籽提取物能明显减缓发酵猪肉香肠的产酸速度和氧化速度,进而提高其氧化稳定性;添加0.25%葡萄籽提取物对提高发酵猪肉香肠氧化稳定性效果最佳。     

High pressure effects on lipid oxidation in minced pork

Washed muscle fibres and minced pork were subjected to high pressure treatment at 800 MPa for 20 min at 20 °C prior to storage at 4 °C. In both cases, high pressure treated samples oxidised more rapidly than the controls, as measured by 2-thiobarbituric (TBA) number. The rate of lipid oxidation of the high pressure treated samples was similar to that induced by heat (80 °C for 15 min). No significant increased rate of oxidation was observed in minced meat samples treated at 300 MPa but above this pressure the rate increased with intensity. Minced meat samples pressure treated in air had higher initial TBA numbers than those treated in nitrogen, but upon storage both oxidised more rapidly than untreated samples. Differential scanning calorimetry, reflectance spectrophotometry and electrophoresis showed that treatment above 300-400 MPa caused marked denaturation of the myofibrillar and sarcoplasmic proteins and conversion of reduced myoglobin/oxymyoglobin to the denatured ferric form. The possible role of these reactions in catalysing lipid oxidation is discussed.     

高压结合热处理对猪肉色泽及脂肪氧化的影响

为研究高压结合一定的温度处理对猪肉色泽及脂肪氧化的影响,并建立两者之间的多元回归模型。以猪背脊肉为原料,以肉色参数红度(a*)、黄度(b*)、亮度(L*)、总色差(△E)和脂肪氧化酸败指标TBARS、过氧化值(POV)、酸价(AV)为测定指标,研究不同温度(25~55℃)下不同压力(100~600 MPa)处理10 min对猪肉色泽及脂肪氧化的影响。结果表明:随着压力和温度的上升,L*值和△E值增加,a*值下降,肌肉逐渐失去红色变为灰白色,同时,TBARS值、过氧化值、酸价显著升高(p<0.05)。利用SPSS软件逐步回归得到色度参数a*、b*和L*与脂肪氧化酸败指标(TBARS、POV、AV)之间的三个最优多元回归方程,经统计检验极显著(p<0.01),预测值与实际测量值之间差异较小,表明模型精确度较高。因此,在高压结合热处理过程中,可以通过色度参数定量预测脂肪氧化程度。      

洋葱皮乙醇提取物对生鲜猪肉色泽、脂质和蛋白质氧化稳定性的影响

为研究洋葱皮乙醇提取物(ethanol extract of onion skins,EEOS)对生鲜猪肉色泽褐变,脂肪和蛋白质氧化以及微生物侵染程度的影响,并与空白对照组和抗坏血酸(ascorbic acid,VC)处理组进行比较,以猪肉亮度值L?、红度值a?,以及高铁肌红蛋白(metmyoglobin,MetMb)...     

高压促进猪肉肌内脂肪氧化过程中脂肪氧化酶的作用

为研究高压促进猪肉肌内脂肪氧化过程中脂肪氧化酶(Lipoxygenase,LOX)的作用,以去除LOX的猪背最长肌为原料,在其中加入事先从猪肉中提取的或外源LOX(大豆脂肪氧化酶),经600MPa、50℃或350MPa、20℃处理并经6d冷藏后,测定各样品高压处理和冷藏后LOX活性和TBARS值。结果表明:LOX对高压下肌内脂肪氧化的启动有重要作用,但其不会影响样品冷藏后的最终氧化状态(TBARS值);在高压处理后的冷藏中,LOX的作用不明显,主要以脂肪自动氧化为主,即使加入5倍浓度的外源LOX,也只引起样品最终TBARS值的少量增加。因此,高压促进猪肉肌内脂肪氧化中主要以自动氧化为主,而LOX的作用很小。      

贮藏条件对猪肉糜氧化效应的影响

将肥瘦比为1:1的猪糜于-18、-24、-40℃三种条件下贮藏,每10d取样一次,通过测定酸价（AV）、过氧化值（POV）和硫代巴比妥酸（TBARS）值,研究贮藏温度、贮藏时间对猪肉糜氧化效应的影响。结果表明,贮藏时间和温度显著影响肉糜的氧化进程（p<0.05）,随贮藏时间的延长,酸价整体呈先上升后下降的趋势,而过氧化值、硫代巴比妥酸值整体呈上升趋势;贮藏温度越低,肉糜的AV值、POV值和TBARS值也越低,且变化缓慢。缩短贮藏时间和降低贮藏温度有利于控制肉糜脂肪氧化,研究表明,贮藏时间小于20d时效果最佳,30d时脂肪水解与氧化达到了动态平衡;-40℃贮藏效果最好,但从节能等角度综合考虑,-24℃更适合作为肉糜长期贮藏的温度。      

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.     

芦丁对冷藏猪肉糜脂肪和蛋白氧化及品质特性的影响

研究不同浓度(0、0.05、0.1和0.2 g/kg)的多酚物质芦丁对冷藏猪肉糜的抗氧化效果及其对肉糜品质特性的影响,并以0.2 g/kg叔丁基羟基茴香醚(butylhydroxyanisole,BHA)作为对照,测定了硫代巴比妥酸值(TBARS值)、总巯基含量、羰基含量、表面疏水性以及猪肉糜的色泽、蒸煮损失和质构特性。结果表明:芦丁对TBARS生成、总巯基损失、表面疏水性的增加具有一定的抑制作用,但对羰基含量不具有抑制作用,且高浓度芦丁反而促进了羰基氧化产物的生成;芦丁能提高肉糜红度值,减少蒸煮损失,并能提高熟肉糜的硬度和弹性等质构特性。因此,适量的芦丁对抑制猪肉脂肪和蛋白氧化以及改善其品质特性具有较好的作用。     

Cytooxidative effects of α‐tocopherol and ascorbyl palmitate on thermal oxidation of canola oil

Canola oil, with and without added α‐tocopherol and ascorbyl palmitate, was used to deep‐fat frying potatoes once per day for 10 day or once per week for 10 weeks. Changes in chemical and physical properties were monitored. Refractive index, free fatty acids and absorbance at 232 and 270 nm increased with frying time. Smoke point, ‘L’ color index, iodine value and the C_18 : 2/C_16 : 0 ratio in the oil decreased with the frying time. According to smoke point, which shows the time of the oil should be discarded, canola oil without antioxidant (control) can be used safely 8 times daily or 7 times weekly. For canola oil with antioxidant (oil + α‐tocopherol + ascorbyl palmitate( the smoke point did not decrease below 170°C in both daily and weekly fryings. This showed that canola oil with antioxidant could be used safely at least 10 times for both frying intervals. In both daily and weekly fryings, the addition of 200 ppm α‐tocopherol and 200 ppm ascorbyl palmitate increased the oxidative stability of canola oil.     

Combined effects of high-pressure and thermal treatments on lipid oxidation and enzymes in pork

Food Science and Biotechnology - The relationship between lipid oxidation and related enzymes in pork during combined pressure-heat treatments was investigated. Minced pork was treated under a...