高温油茶籽油中苯并芘和反油酸产生规律研究

为了探讨高温条件下油茶籽油中苯并芘和反式脂肪酸的形成规律进行了研究。试验测定了不同温度、时间、煎炸不同食材后2种油茶籽油中苯并芘和反油酸以及烟气中苯并芘的含量。结果表明高温条件下,油茶籽油中苯并芘含量未随加热时间延长而明显提高;但反油酸含量随加热时间和温度上升趋势明显。油茶籽油在180℃下煎炸香蕉、面条、瘦肉、豆腐等食材12 h后苯并芘含量大幅上升,且煎炸豆制品上升速度最快;压榨毛油煎炸香蕉和豆腐24 h后油中反油酸仍低于检出限(0.05%),而煎炸面条和瘦肉后,油中反油酸上升明显,分别达到1.9%和0.6%;浸提精炼油中煎炸4种食材后反油酸含量均有显著上升,上升幅度依次是面条豆腐香蕉瘦肉。     

花椒风味油茶籽油制备及挥发性物质分析

目的:为改善油茶籽油的特殊气味,以油茶籽油和花椒为原料开发花椒风味油茶籽油。方法:研究不同工艺条件下花椒风味油茶籽油的过氧化值、酸价、脂肪酸组成和气味变化。结果:当料液比(m_花椒∶m_油茶籽油)为10∶100、煎炸温度为180℃、煎炸时间为5 min时,制备所得样品的酸价为0.400 7 mg/g、过氧化值为0.030 4 g/100 g、羟基-β-山椒素含量为2.225 mg/g,料液比对花椒风味油茶籽油的主要脂肪酸含量影响较小;油茶籽油和花椒风味油含有油茶籽油的关键风味物质(E)-2-辛烯醛和庚醛。结论:花椒风味油茶籽油具备花椒油的特殊风味物质芳樟醇和柠檬烯,可有效改变油茶籽油的风味。     

不同煎炸条件对茶叶籽油苯并（a）芘含量的影响

以茶叶籽油为煎炸用油,研究了不同煎炸原料、煎炸温度和煎炸时间对茶叶籽油苯并(a)芘(BaP)含量的影响,并对其氧化指标进行了初步测定。结果表明:煎炸鸡翅的茶叶籽油180℃煎炸10 h后BaP含量最多,为8.82μg/kg,其次为煎炸豆腐和土豆的茶叶籽油,煎炸油条的茶叶籽油BaP含量最少;煎炸原料中BaP的增加量为鸡翅土豆豆腐油条;以鸡翅为原料煎炸温度越高,茶叶籽油中BaP生成量越多,200℃煎炸10 h后BaP含量达11.86μg/kg;随煎炸时间的延长,BaP含量上升速率加快,180℃煎炸50 h后茶叶籽油BaP含量由1.92μg/kg上升至16.13μg/kg,此时过氧化值、酸值(KOH)和茴香胺值分别为18.75 mmol/kg、3.32 mg/g和77.25。     

加热前后油茶籽油气味特征变化的规律研究

利用电子鼻和气相色谱-质谱联用(GC-MS)分别从整体气味和挥发性成分两方面对不同热处理条件的油茶籽油进行了分析测定。结果表明:利用电子鼻对不同温度油茶籽油气味成分的样品间进行分析具有良好的区分度;在低温加热(30~90℃)时,随加热时间延长油茶籽油气味轮廓趋于稳定,高温加热(120~150℃)20 min后随加热时间的延长油茶籽油气味轮廓呈现发散性,规律与GC-MS测定结果一致;利用电子鼻建立的油茶籽油气味模型可以对未知油茶籽油样品的加热温度和加热时间进行定量预测,预测加热温度的模型中,当加热时间为20 min和40 min时,相对偏差分别为7.9%和3.6%;在预测加热时间的模型中,当加热温度为60℃和90℃时,相对偏差分别为14.0%和11.3%;GC-MS结果表明加热后油茶籽油的挥发性物质中杂环类、部分酸、醛、醇类物质含量呈上升趋势,己醛、环戊烷、环辛烷含量随加热温度升高先增加后减少;辛烯醛和2,4-壬二烯醛的含量随加热温度升高和加热时间的延长而减少,以上现象推测来源于脂肪氧化降解、斯特雷克儿氨基酸反应或美拉德反应的Strecker降解。     

影响猪胰脂酶催化油茶籽油与亚油酸甲酯酯交换过程中酯交换量和酰基位移因素的研究

研究了无溶剂体系下猪胰脂酶催化油茶籽油与亚油酸甲酯酯交换反应过程中酯交换量和酰基位移的变化。结果显示,反应时间、酶的水活度、加酶量和反应温度对酯交换和酰基位移都有影响。加酶量和反应温度对酰基位移和酯交换量有直接影响,反应时间和酶的水活度通过影响酯交换速率来影响酰基位移。对猪胰脂酶来说,酯交换时酶的水活度在0.12~0.55之间,加酶量不大于10.0%,温度在40~45℃之间,控制合适的反应时间可使产物甘三酯的酰基交换程度较高(24%左右),酰基位移较小(小于5%)。     

煎炸油中极性物质与酸价之间的相关性研究

本实验以油茶籽油、橄榄油和棕榈油为研究对象,研究经过180℃下油炸薯条后三种油的酸价与极性物质的相关性以及主要脂肪酸的变化。发现,三种油随着油炸时间的增加酸价(p0.05)显著增大。油茶籽油、橄榄油和棕榈油的最终酸价分别为0.32、0.66、0.58mg/g。经过20次油炸,三种油的总极性物质(TPC)显著增加,油茶籽油、橄榄油和棕榈油总极性物质分别为16.01%、20.91%和17.66%。随着油炸时间的增加,三种煎炸油的饱和脂肪酸含量显著增加。不饱和脂肪酸的含量变化较大,C18∶2和C18∶3显著下降,而C18∶1逐渐下降。     

基于甘三酯指纹图谱及化学计量学的青海亚麻籽油掺假识别研究

采用HPLC-RID测定青海省亚麻籽油甘三酯组成,并利用指纹图谱相似度评价系统及判别分析对亚麻籽油进行掺伪识别分析。结果表明,亚麻籽油中共检测出8种甘三酯,其中主要甘三酯为OLnLn(22.82%)、LnLnLn(20.40%)、OLnO(14.81%)、OLLn(13.59%);运用指纹图谱相似度评价系统构建亚麻籽油甘三酯标准指纹图谱以鉴定亚麻籽油中掺入菜籽油、大豆油、花生油、葵花籽油、玉米油、芝麻油(10%、20%、30%、40%、50%)的掺伪样品,当掺入植物油质量分数达10%以上时,可以准确判别纯亚麻籽油和掺伪亚麻籽油。为进一步识别亚麻籽油中掺假的植物油种类,对掺伪油样进行判别分析,建立的判别模型适用于亚麻籽油中掺入大豆油质量分数大于10%、掺入菜籽油、花生油、葵花籽油、玉米油、芝麻油浓度大于20%时的掺伪油种类的识别鉴定。     

沙棘油脂肪酸、sn-2位脂肪酸及甘三酯的测定与分析

采用超临界CO_2萃取得到沙棘籽油和沙棘全果油,并采用气相色谱和超高效液相色谱-飞行时间质谱对其脂肪酸、sn-2位脂肪酸及甘三酯组成进行测定与分析。结果表明:沙棘籽油中亚油酸、亚麻酸和油酸的含量较多,分别为38.71%、25.66%和20.68%,这3种脂肪酸也是其主要的sn-2位脂肪酸,含量分别为46.46%、25.49%和23.02%;LOL(13.65%)、OLO(12.06%)和LLn O(11.23%)是沙棘籽油的主要甘三酯类型;沙棘全果油中棕榈油酸(36.86%)、棕榈酸(27.27%)和油酸(18.00%)的含量较高,主要的sn-2位脂肪酸为棕榈油酸(45.57%)和油酸(32.06%);沙棘全果油的主要甘三酯为POPo(14.38%)、PoOPo(13.77%)和OPO(12.06%)。     

煎炸不同食材的花生油中极性组分与氧化甘三酯聚合物含量的相关性研究

利用花生油分别对油条、薯条、鸡翅、豆腐4种食材进行32 h连续煎炸,对每隔2 h所取煎炸油样进行极性组分、氧化甘三酯聚合物含量的检测,并与不加任何食材的空白煎炸油脂进行对比,分析研究花生油连续煎炸不同食材过程中极性组分、氧化甘三酯聚合物及其他指标的综合变化。结果表明:随煎炸时间的延长,煎炸油中极性组分、氧化甘三酯聚合物含量升高,煎炸油酸值升高、色泽加深,反式脂肪酸含量升高,经32 h连续深度煎炸,油条、薯条、鸡翅、豆腐、空白5种煎炸油中极性组分从初始的3.34%分别增至32.98%、30.61%、15.50%、29%、47.02%,其中油条、薯条、鸡翅、空白煎炸油中极性组分含量分别在32、24、30、16 h时超出27%的国标限量。氧化甘油三酯聚合物含量从初始的0.43%分别增至18.97%、23.68%、6.52%、16.92%、38.83%。煎炸油中极性组分与氧化甘油三酯聚合物含量间存在极显著的线性相关(P0.01),R2分别为0.996 4、0.993 7、0.9972、0.974 0、0.991 2。经32 h连续煎炸,5种煎炸油的酸值从初始的0.17 (mgKOH/g)的分别增至7.15、2.24、2.39、2.75、2.18(mg KOH/g);反式酸含量从初始的0.17%增加至0.34%、0.28%、0.39%、0.38%、3.54%。     

牡丹籽油的脂肪酸组成及理化特性分析

实验在分析测定牡丹籽油的理化特性指标的基础上,采用气相色谱仪分析了牡丹籽油的脂肪酸组成含量,其不饱和脂肪酸含量高达92.00%。这些不饱和脂肪酸主要以油酸、亚油酸、亚麻酸为主,含量分别为23.92%、27.58%、40.50%;采用棒状薄层色谱-氢火焰离子化检测器测得牡丹籽油中除游离脂肪酸外,含有95.89%的甘三酯和4.11%的甘二酯;猪胰脂酶水解分析牡丹籽油的Sn-2脂肪酸组成,结合1,3-随机-2-随机分布学说计算出牡丹籽油甘三酯组成。牡丹籽油中主要是以油酸、亚油酸和亚麻酸为主的甘三酯,其中三不饱和脂肪酸甘三酯的含量达到71.00%以上,一饱和二不饱和脂肪酸甘三酯含量大于15.00%;高压液相色谱法测定牡丹籽油中维生素E总含量为0.56 mg/g;Rancimat法测定的氧化稳定性结果为110℃,2.85 h。为牡丹籽油的进一步研究和深度开发利用提供参考依据。     

Frying Oil Temperature: Impact on Physical and Structural Properties of French Fries During the Par and Finish Frying Processes

The physical, mechanical, and structural changes in French fries at different frying temperatures (170, 180, and 190 °C) during par and finish frying were investigated. The experimental frying process includes blanching, par frying, freezing, and finish frying at the point of consumption. Par frying temperature had a greater effect on moisture reduction than on processing time with the greatest moisture loss at 180 °C after 160 s. At 180 °C, fries had the highest total oil uptake (29.56 % wb). Frying caused a significant change in color with the greatest effect at 190 °C. Micro-CT scan images showed structural changes in French fries over the course of the frying process. Frying time increased the volume of the pores relative to the size of the crust, and this was positively correlated with the hardness and shear cutting force. Overall, within the range of frying conditions studied, the higher temperature (190 °C) resulted in the lowest amount of oil uptake and the crispiest texture.     

Effect of the Addition of Basil Essential Oil on the Degradation of Palm Olein during Repeated Deep Frying of French Fries

The potential antioxidant power of basil essential oil under frying conditions was explored. Two concentrations (200 or 500 ppm) were added to palm olein (PO) to evaluate their effect on fat oxidation/degradation during repeated frying of French fries at 180 °C. A higher oxidative stability index was detected for PO with basil essential oil at 200 ppm. Both concentrations showed lower p‐anisidine values than PO without basil essential oil after 5 d of frying. Addition at 500 ppm resulted in the lowest total polar compounds and free fatty acids contents. Thus, the addition of basil essential oil improved the performance of PO during repeated frying of French fries.     

Physicochemical Properties Changes of Donuts During Vacuum Frying

Vacuum frying was explored to cook donuts and compared to the conventional atmospheric frying. A temperature of 190°C was used for atmospheric frying. Three vacuum levels (3, 6, and 9 kPa vacuum) with three temperature levels (150, 165, and 180°C) were used for vacuum frying. The effects of initial moisture content (IMC), vacuum level and frying temperature on physicochemical properties, such as moisture loss, oil absorption, and quality were investigated. The properties of fried donuts were significantly affected by IMC. Under vacuum frying, volume and total color changes were affected by frying temperature; and oil uptake was affected by vacuum and frying temperature. Frying temperature and vacuum were not directly related to the final moisture content (MC) of donuts. There was no relationship between MC and fat content of donuts. Donut texture was directly related to the vacuum and frying temperature.     

Quality assessment of refined oil blends during repeated deep frying monitored by SPME–GC–EIMS,GC and chemometrics

The aim of this study was to investigate the effect of the refined palm oil addition (20%) on the fatty acid and sterol compositions of refined olive oil or refined soya bean oil and also to investigate the formation of total polar compounds and volatile compounds in these oil blends during fifty successive deep‐frying sessions of potato fries at 180 °C. The blend of refined olive oil and refined palm oil exhibited a higher chemical stability during the frying process than that of refined soya bean oil and refined palm oil. Indeed, the total polar compounds and volatile compounds formed, especially 2,4‐decadienal, were found to be relatively increased in the refined soya bean oil/refined palm oil blend reaching 36.50% and 46.70%, respectively, after fifty deep‐frying sessions. Moreover, the degradation of linoleic acid and β‐sitosterol was significantly (P < 0.05) observed for the refined soya bean oil/refined palm oil blend. The results have proven that the proper blending of monounsaturated refined olive oil with refined palm oil increases its stability and hence improves the quality of such olive oil during frying process.     

Quality changes of edible oils during vacuum and atmospheric frying of potato chips

Demand for safe and nutritionally rich fried products is gaining a momentum among consumers, leading to the increased consumption of vacuum fried products. The impact of vacuum frying (VF)(110 °C, 40 kPa) on chemical composition of food, fatty acid profile, microstructure, oxidative stability and sensory attributes was assessed and differentiated with that of atmospheric frying(AF) (180 °C). The potato slices were fried in mustard and soyabean oil used repetitively for 25 h. The oil content of VF potato chips was lower (15.18%) than AF chips (18.98%), however water loss in AF chips was higher than VF chips by 1.63-fold. VF significantly prevented the PUFA degradation, minimizes transfatty acid (TFA) formation and maintain a low C18:2/C16:0 ratio as compared to AF. VF Chips fried in soyabean oil show an increase in TFA content from 2.15 to 2.63% and a decrease in PUFA from 51.57 to 45.16% as compared to AF chips where TFA content increased from 2.15 to 3.72% and PUFA shows a higher reduction from 51.57 to 37.69% at the end of 25 h of frying. This indicate that in AF, oil is safe for use upto 10 cycles of frying, while as in VF, the same oil can be used for upto 40 cycles of frying without quality deteoriation. Sensorial analysis revealed that VF chips retain a better colour, taste and flavour but were less crispy than that of AF chips. These findings validate the application of vacuum frying technology for the production of high-quality foods with lesser degradation of frying oil.Industrial relevanceFood manufacturers are now impelled by the health-conscious consumer base for the production of healthy food products. The toxic effect of foods fried in degraded oils on human health is now widely known and thus the production of safe fried foods is the need of hour globally. In this context, vacuum frying is the most feasible approach for the production of quality fried products retaining the natural colour, flavour, sensory and nutritional properties better than that of atmospheric frying. Vacuum frying causes the least degradation of fatty acid of the frying oil and the fried potatoes, producing healthy potato chips. Therefore, the oil used for vacuum frying have a greater shelf life and oxidative stability than atmospheric frying. However, the higher installation cost of vacuum fryer still limits its use in the street fried food market, where degradation of oil is more likely. Thus, for its widespread commercialisation in developing countries, steps should be taken both by government and manufacturing companies to reduce the installation costs.     

The Influence of Drying Process Conditions on the Physical Properties,Bioactive Compounds and Stability of Encapsulated Pumpkin Seed Oil

In this study, the influence of encapsulation process conditions on the physical properties and chemical composition of encapsulated pumpkin seed oil was investigated. Four variants of encapsulated oil were prepared: spray-dried non-homogenized emulsions at the inlet temperatures of 180 and 130 °C, spray-dried homogenized emulsion at the inlet temperature of 130 °C, and freeze-dried homogenized emulsion. The emulsion was prepared by mixing 10.6% oil with 19.8% wall materials (15.9% maltodextrin + 0.5% guar gum + 3.9% whey protein concentrate) and 69.6% distilled water. The quality of encapsulated pumpkin seed oil was evaluated by encapsulation efficiency, surface oil, total oil and moisture contents, flowing properties, color, and size. Additionally, fatty acid composition, pigment characteristics, and the content of bioactive compounds (tocopherols, squalene, and sterols) were determined. Changes of these components after the encapsulation process in comparison to the control pumpkin seed oil were considered as stability parameters. The highest encapsulation efficiency was obtained by spray-drying at the inlet temperature of 130 °C. Generally, the spray-drying process had a positive effect upon the physical parameters of encapsulated pumpkin seed oil but results were dependent on process conditions. The higher inlet temperature generated more surface oil, but capsules obtained at the lower temperature were greater in size and more deformed. Although freeze-drying proceeded at a very low temperature, the powder obtained with this technique was characterized by the highest bioactive compound losses (with the exception of sterols) and the lowest stability. The homogenization process applied before spray-drying affected greater polyunsaturated fatty acid, squalene, and pigment degradation. In conclusion, results of the study showed that the spray-drying non-homogenized emulsion was a more recommendable technique for the encapsulation of pumpkin seed oil because of smaller changes of native compounds and better oxidative stability.     

Oxidative Stability of Soybean and Sesame Oil Mixture during Frying of Flour Dough

ABSTRACT: Effects of roasted sesame seed oil on the oxidative stability of soybean oil during frying of flour dough at 160 °C were studied by determining fatty acid composition and conjugated dienoic acid (CDA), p -anisidine (PA), and free fatty acid (FFA) values. Concentration of sesame oil in frying oil was 0%, 10%, 20%, or 30% (v/v). Tocopherols and lignan compounds in the frying oil were also determined by high-performance liquid chromatography. As the number of fryings performed by the oil increased, linolenic acid content in frying oil decreased, and the decreasing rate was lower in frying oil containing sesame oil than in the oil containing no sesame oil. CDA and FFA values of frying oil increased during frying and their relative values to the initial value were lower in frying oil containing sesame oil than in the oil containing no sesame oil. This indicates that the addition of sesame oil improved thermooxidative stability of frying oil, possibly due to the presence of lignan compounds in sesame oil. Tocopherols and lignan compounds in frying oil decreased during frying. As the amount of sesame oil in frying oil increased, degradation of tocopherols increased and lignan compounds degradation decreased. Tocopherols were suggested to protect lignan compounds in sesame oil from decomposition during frying.     

Short-Chain Fatty Acid Formation during Thermoxidation and Frying

Formation and evolution of the short-chain fatty acids originated by oxidation and remaining bound to the parent triglyceride, specifically heptanoate and octanoate, were studied during thermoxidation of palm olein, conventional sunflower oil and high-oleic sunflower oil at 180°C, as well as in real used frying oils of unknown history collected by Food Inspection Services. Fatty acids were quantified by gas–liquid chromatography following transesterification of samples and using methyl nonanoate and methyl heptadecanoate as internal standards. Alteration level was determined through analyses of polar compounds and polar fatty acids. Results showed high correlation coefficients between short-chain fatty acids and polar compounds or polar fatty acids, thus suggesting that quantification of short-chain fatty acids is a good indication of the total alteration level in used frying oils.     

Anti‐radical power gives insight into early lipid oxidation events during frying

The aim of this research was to use anti‐radical power (ARP) to study early lipid oxidation events during frying. The 2,2‐diphenyl‐1‐picrylhydrazyl radical (DPPH?) test was used to determine the ARP. As oil does not dissolve completely in methanol, which is generally used for the DPPH? test, butanol was used instead. Changing the solvent did not influence the value of the ARP. The decrease of the ARP highly correlated with the increase of the peroxide value for soybean oil heated at 110 °C (R² = 0.99). Sensory analysis showed that rancidity of soybean oil and frying oil, heated at 180 °C, was perceived before the ARP decreased. Once the oil was perceived as rancid, the intensity of rancidity did not change significantly upon further heating. The ARP of soybean oil was found to decrease faster at 110 °C than at 180 °C, suggesting different mechanisms of radical formation. The total polar compounds of frying oil in which French fries were fried did not differ significantly from frying oil that was heated alone. However, frying of French fries caused more hydrolysis of the oil, while the ARP decreased faster when the oil was heated alone. Copyright © 2006 Society of Chemical Industry     

茶籽油微胶囊的制备及其产品特性研究

本研究采用喷雾干燥法制备了茶籽油微胶囊粉末油脂,并对产品配方和喷雾干燥工艺参数进行了优化,同时系统分析了产品的理化性质、稳定性和体外释放特性。试验结果如下：最佳配方为麦芽糊精/大豆分离蛋白/阿拉伯胶质量比为1:1.5:1.5,芯材/壁材质量比为1:1.5,乳化液固形物含量为20%；喷雾干燥加热温度为180°C,进料泵速25r/min,雾化压力为0.025Mpa。茶籽油微胶囊包埋率为89.43%,产品具有较高的氧化稳定性。体外模拟消化试验数据显示,该产品主要在肠液中释放,最终释放率为94.03%。本试验结果能为茶籽油的高值化利用提供必要理论支撑和技术途径。