微波预处理火麻籽对油的品质及抗氧化活性的影响

为考察微波预处理火麻籽(Cannabis sativa L.)对油的品质及抗氧化活性的影响,将火麻籽置于微波功率560W条件下预处理7min,冷却至室温后低温压榨制油。结果表明,微波预处理显著增加了油的酸价、过氧化值,降低了油的水分及挥发物含量,使油脂色泽变深,而脱壳处理可使色泽得到明显改善;火麻籽油中检出8种脂肪酸,其中油酸、亚油酸和亚麻酸是主要的脂肪酸,含量分别为13.88%、57.59%、16.33%,n-6/n-3脂肪酸为3.52∶1,是一种脂肪酸平衡合理的植物油;微波预处理不影响油的脂肪酸组成,使油中总酚含量增加1倍,总维生素E和植物甾醇含量分别增加41.99mg/kg和58.68mg/100g;微波预处理火麻籽显著改善了油的氧化稳定性,提高了油的抗氧化活性,与未经微波预处理的压榨火麻籽油相比,微波预处理后油的氧化诱导期延长了1.05h,DPPH自由基清除活力和FRAP总抗氧化能力分别增加8.46和81.85μmol/100g。表明微波预处理是一种适宜于提高火麻籽油品质的预处理方式。     

微波预处理时间对油菜籽及产品中芥子酸衍生物的影响

以白菜型、甘蓝型、芥菜型三种类型油菜籽为原料,比较了在微波预处理和制油过程中,芥子酸、芥子碱、Canolol在油菜籽、菜籽油、压榨饼和脱脂粕中的变化规律以及油菜籽类型间的差异;分析了微波预处理过程中Canolol含量与芥子酸、芥子碱含量的相关性,为进一步研究Canolol的转化途径和机制提供依据。结果表明,甘蓝型油菜籽中芥子酸和Canolol含量显著高于芥菜型和白菜型,而芥菜型油菜籽中芥子碱含量显著高于其他两个品种。微波预处理时间对油菜籽、菜籽油、压榨饼和脱脂粕中芥子酸、芥子碱和Canolol的含量均有显著影响(P0.05);随微波时间的延长,三种油菜籽中芥子酸、芥子碱含量均持续降低,甘蓝型油菜籽中Canolol含量先增加后减少,微波时间1~4min时,芥菜型和白菜型油菜籽中未检测到Canolol,之后随微波时间的延长Canolol含量增加。随微波处理时间的延长,菜籽油中芥子酸和Canolol含量先增加后降低,芥子碱含量则持续增加;压榨饼和脱脂粕中芥子酸和芥子碱含量均随微波时间的延长而显著降低(P0.05);微波预处理过程中,油菜籽中Canolol含量与芥子酸(-0.977)和芥子碱(-0.962)含量极显著负相关,Canolol的增加量远高于芥子酸的减少量,且与芥子酸减少量(0.967)和芥子碱减少量(0.978)极显著正相关。含量上的增减结果暗示油菜籽中芥子碱可能通过一定途径转化为Canolol。     

微波焙烤咸干花生在贮藏过程中的品质与风味变化

选取生产上有代表性的鲁花、四粒红、大白沙3个花生品种,采用中试规模的隧道式微波炉进行干燥脱水,制备微波焙烤咸干花生产品,冷却后密封分装保存于室温(20℃)条件下,考察贮藏过程中产品主要理化指标酸价、过氧化值、水分含量和7种典型挥发性风味物质[2,5-二甲基吡嗪、2-乙基-3,5（6）-甲基吡嗪、2-乙基-6-甲基吡嗪、2-戊基呋喃、2,3-二氢苯并呋喃、苯甲醛、苯乙醛]含量的变化,采用Rancimat法推算产品货架期。发现随贮藏时间的延长,酸价、过氧化值增加,风味物质含量降低,其突变拐点均出现在27周左右,与产品货架期一致。进一步数据分析表明,酸价、过氧化值与水分含量呈显著的线性关系（p＜0.000 1）,其中酸价与水分含量的相关系数（R2值）为0.920 9,过氧化值与水分含量的R2值为0.963 9;典型相关性分析表明,风味成分含量与油脂氧化之间的相关关系显著,其中过氧化值与风味成分含量的关联度最大,R2值为0.993 0。原料不同,贮藏过程中微波焙烤花生品质和风味的变化也表现出一定差异,大白沙花生的酸价、过氧化值优于鲁花、四粒红,良好风味物质的总含量更高、损失速度更低,不良风味物质的含量更低、损失速度更高,与鲁花、四粒红相比,大白沙更适宜于生产微波焙烤咸干花生产品。     

抹茶蛋卷贮藏品质与货架期预测模型研究

当前抹茶烘焙食品广受消费者青睐，对抹茶烘焙食品贮藏品质进行研究具有重要的实际应用意义。本文以抹茶蛋卷作为研究对象，采用食品保质期加速测试法，研究其贮藏过程中水分含量、过氧化值、酸价和色差的变化，并基于Arrhenius模型构建抹茶蛋卷的货架期预测模型。结果表明：抹茶蛋卷在贮藏过程中随着时间的延长水分含量、色差L值和b值较为稳定，色差a值呈上升趋势，过氧化值逐渐增加，酸价呈现先增加后减少的趋势。以色差a值作为主要品质劣变指标，进行零级反应动力学方程拟合，建立抹茶蛋卷货架期预测模型，25℃条件下预测货架期为325.39 d。     

微波技术对油菜籽品质影响研究进展

微波技术作为一种高效的加工手段,在菜籽加工过程中的应用逐渐引起了关注。菜籽压榨前微波预处理能将菜籽油中油菜籽多酚含量提高近120倍之多,菜籽油中植物甾醇、维生素E的含量也能得到显著提升。此外,微波预处理还能加速硫甙的降解,与传统炒籽预处理相比,微波菜籽油香味更浓郁丰富。本文围绕微波技术在油菜籽加工领域的应用展开论述。     

微波预处理对油菜籽及其低温压榨油脂肪酸含量的影响

为了解微波预处理对油菜籽及菜籽油脂肪酸含量的影响，评价其产生反式脂肪酸的风险，以8个省14产地的57份油菜籽样品为材料进行微波预处理，并对微波前后的油菜籽进行压榨，得到冷榨菜籽油。采用优化后的气相色谱法快速测定油菜籽和菜籽油中脂肪酸组成和含量，考察油菜品种、油菜产地以及微波预处理对油菜籽脂肪酸含量的影响。结果发现，与国标方法相比，优化后样本分析时间缩短一半以上，显著提高分析通量。研究发现，产地对油菜籽和冷榨菜籽油脂肪酸组成和含量影响较小，品种对菜籽和冷榨菜籽油脂肪酸组成和含量影响较大。不同品种的油菜籽和对应冷榨菜籽油中的脂肪酸含量差异极显著（P＜0.01）。高芥酸菜籽的花生一烯酸、芥酸的平均含量分别是低芥酸菜籽的6.89倍和64.50倍，油酸的平均含量仅为低芥酸菜籽的71.48%。同一品种不同产地的油菜籽与对应的冷榨菜籽油中的脂肪酸含量之间，不存在显著性差异。微波预处理不会显著影响油菜籽和菜籽油中的脂肪酸组成和含量水平，同时也不会产生反式脂肪酸等风险因子，微波处理后，产生反式脂肪酸的风险较低。     

响应面优化亚临界萃取菜籽低温压榨饼中油脂的工艺及其品质评价

采用Box-Behnken响应面设计优化亚临界萃取菜籽低温压榨饼中油脂的工艺，并将所得油的品质与正已烷、超临界CO2萃取油进行比较。结果表明：液料比和萃取时间对油脂提取率的影响极显著(p<0.01)；液料比与萃取时间存在显著的交互作用（p<0.05）；经优化后，在35℃下，设定液料比为8.3 mL/g，萃取90 min，菜籽油的提取率最高达95.10%。通过亚临界萃取得到的菜籽油磷含量为113.20mg/kg，约为正已烷萃取菜籽油(磷含量232.48mg/kg)的一半，油脂酸价与过氧化值都较正已烷萃取菜籽油低；亚临界萃取的菜籽油除磷含量与超临界萃取菜籽油差异显著外，其它品质指标，如酸价、过氧化值、甾醇及生育酚含量均与超临界萃取油差异不明显。     

茶多酚在鱼糜贮藏中的应用

将茶多酚添加到鱼糜中,研究冷藏或冷冻鱼糜的含水量、凝胶强度、酸价、过氧化值、挥发性盐基氮等的变化。结果表明,茶多酚能降低冷藏鱼糜的酸价、过氧化值、挥发性盐基氮;对冷藏鱼糜和冷冻鱼糜水分含量的减少均有一定的抑制作用;添加茶多酚能显著延缓冷藏鱼糜凝胶强度的降低,而对冷冻鱼糜凝胶强度的影响不明显。     

微波膨化加工木菠萝脆片工艺

通过对不同预处理后的菠萝蜜苞片进行微波膨化,研究了预处理方式、水分含量对微波膨化的影响和不同的固化处理方式,并对产品的脱水率、膨化率、酥脆度、色泽、外形平整性进行评价。结果表明∶采取"微波脱水＋热风干燥"方式使苞片水分质量分数降至15%时,经微波膨化30s,产品的品质最好,膨化率最高（约为100%）;不同温度热风干燥方式、"微波脱水+热风干燥"方式对最高膨化率无影响,但对脆片的感官品质有不同影响;将脆片45℃热风干燥4h后放在5℃低温保藏可提高酥脆度。     

罐装绿茶水浸提条件的研究

采用L2 5(56 )正交实验设计研究了罐装绿茶水浸提的温度、时间和茶水比对其品质的影响。结果表明 ,随浸提温度的升高和时间的延长 ,茶汤干物浸出率增加、色泽变黄 ,混浊度明显增加。每克茶用水量超过 6 0ml时 ,茶汤干物浸出率和混浊度的变化不明显。为了保持原茶风味 ,降低茶汤浑浊度 ,以及提高干物浸出率 ,确定浸提工艺为 :浸提温度 6 0℃ ,时间 15min ,茶水比 1∶6 0。     

Extraction of pennycress (Thlaspi arvense L.) seed oil by full pressing

Pennycress is currently being developed as an oilseed crop for biofuel production. Pennycress seeds harvested from a field near Peoria, Illinois, provided our first opportunity to conduct an oil extraction study on a pilot scale. The goals of this study were to determine the effects of seed moisture and cooking on the pressing characteristics of pennycress seeds and to evaluate the quality of the oils extracted. Pennycress seeds (60 kg) with 9.5 and 16% moisture contents (MC) were cooked and dried (82–104 °C) using a steam-heated 3-deck laboratory seed cooker. The residence times were varied to produce cooked seeds with MCs ranging from 1.0 to 13.0%. The cooked seeds were pressed immediately using a heavy duty laboratory screw press. Pressing rate, press load, and residual oil in the press cakes were determined. The oils extracted were analyzed for solids content (foots), free fatty acid (FFA) content, color, and phosphorus (P), calcium (Ca), magnesium (Mg), and sulfur (S) contents. Pressing uncooked pennycress seeds with 9.5% MC produced press cake with 10.7% oil (db), extracting 75.1% of the oil in the seed. Cooking and drying the seeds between 3 and 4% MC provided the highest oil recovery at 86.3 and 88.0% for seeds with 9.5 and 16% starting seed MC, respectively. The pressing rates and press loads at these MCs were similar. Compared to the oil from uncooked seeds, the oils from cooked seeds had higher foots (1.55–1.73% vs. 0.52%), slightly higher FFA contents (0.40–0.46% vs. 0.30%), and slightly higher red values in AOCS RY color scale (4.1R–6.2R vs. 2.4R). Cooking increased the phosphatide content but the amount was still comparable to degummed oils. The sulfur levels in the expelled oil were higher than the amounts found in rapeseed oil and varied considerably depending on the seed moisture and the extent of cooking employed.     

Effect of ageing on quality of jojoba oil from Indian locations

Jojoba oil is a source of specialty chemicals and its uses for industrial application are gaining in adaptability and importance. For prolong use of jojoba oil, the details of its storage behaviour are required. This information is scarce for the products obtained from Indian locations. In this study, the ageing effect on the quality of oils was studied for oils from five locations of Rajasthan (India). The oils were extracted/expelled from the seeds that contained 2.5–3.9 wt.% moisture and 42–50 wt.% oil.Physico-chemical properties were determined by standard analytical test methods. Effect of storage time on quality of solvent extracted oil samples with respect to acid value, iodine value, saponification value and peroxide value were determined. The samples were stored for 18 months in the laboratory under climatic condition prevailing in Dehradun (India) during study period. The analysis of samples was done at an interval of 3 months. The properties of jojoba oils compare well with the International Jojoba Expert Council (IJEC) specifications. During storage, acid values, iodine values and peroxide values of the oil increase with time while saponification values remain almost unchanged.     

Frying stability of Moringa stenopetala seed oil

The frying performance of Moringa stenopetala seed oil (extracted with cold press or n-hexane) was studied especially as regards repeated frying operations. The oils were used for intermittent frying of potato slices and cod filets at a temperature of 175 degrees C for 5 consecutive days (5 fryings per day). The chemical changes occurring in oils were evaluated. Free fatty acid content, polar compounds, colour and viscosity of the oils all increased, whereas the iodine value, smoke point, polyunsaturated fatty acid content, induction period and tocopherol content decreased. The effect of the oil on the organoleptic quality of these fried foods and the theoretical number of frying operations possible before having to discard the oil was also determined. The analytical and sensory data showed that the lowest deterioration occurred in cold press produced oil.     

Extraction of Cinnamomum longepaniculatum deciduous leaves essential oil using solvent-free microwave extraction: Process optimization and quality evaluation

The optimal process conditions for solvent-free microwave extraction (SFME) of essential oils from Cinnamomum longepaniculatum deciduous leaves after moisture conditioning were established by response surface methodology (RSM). A Box-Behnken design (BBD) was applied to evaluate the effects of three independent variables: moisture content (A: 54%–74%), microwave power (B: 300–500 ​W) and microwave time (C: 20–40 ​min), on the extraction yield of essential oil. The compounds of the essential oils obtained by SFME, hydro-distillation and microwave-assisted hydro-distillation (MADE) were identified by gas chromatography-mass spectrometry (GC-MS), and the total lipids of C. longepaniculatum fresh leaves and deciduous leaves were analyzed. The correlation analysis of the response regression model indicated that quadratic polynomial model could be employed to optimize the extraction of essential oil. The optimal extraction condition was A: 58%, B: 400 ​W and C: 28 ​min. In the optimal condition, the maximum extraction yield was 4.475 mL/100 ​g dw and higher than that by MADE. The main compound of the essential oil was eucalyptol (63.54%), and total oxygenated compounds was 78.95%, mainly caused by SFME and the metabolism of endophytic bacteria with decreasing content of phospholipids and fatty acids. Analysis of variance under the extraction condition illustrated high fitness of the model and the success of RSM for optimizing and reflecting the expected process condition. SFME combined with moisture regulation was an effective method for extracting essential oil from C. longepaniculatum deciduous leaves.     

Flavor and chemical evaluation of partially hydrogenated sunflower oil as a potato chip frying oil

A partially hydrogenated sunflower oil was compared with a cottonseed-corn oil mixture for frying potato chips. Chips fried in each oil were organoleptically evaluated at two-week intervals during 10 weeks of storage at room temperature. Statistical evaluation of the hedonic ratings of the chips indicated no significant difference in flavor between the chips fried in sunflower oil and those fried in cottonseed-corn oil. Paired comparison testing of chips stored for 2 and 10 weeks indicated no preference for chips fried in the cottonseed-corn oil mixture over those fried in the hydrogenated sunflower oil. The oil content of the chips fried in both oils ranged from 37.6 to 42.9% suggesting an excessive absorption of oil by the chips. The peroxide values of the oils extracted from the potato chips indicate a trend toward greater autoxidation of the cottonseed-corn oil mixture compared to the sunflower oil. During storage, changes in the fatty acid composition of oils extracted from potato chips were minor. Chemical evaluation of oil samples taken during frying runs showed that both oils were of good quality after 23 hours of frying chips.     

Seed oil extraction using a solar powered screw press

An efficient and economical oil expression system that can operate on solar power in rural areas of underdeveloped and developing countries is needed. Recent improvements in both oil extraction and solar energy technologies have indicated the possibilities for fabricating oil extraction equipment. Thus, the objective of our study was to develop a simple oil expression unit capable of producing high quality oil based on solar energy in remote rural areas. A photovoltaic (PV), batch operated, low-pressure oil press, using a 190 W, 12 V dc motor, was designed, fabricated, and tested using coconut and groundnut as the raw material. Samples used in the study were ground to particle size between 500 μm and 2 mm and were pressed at 12 ± 1% moisture content. The press was evaluated based on the oil extraction efficiency (OEE), power consumption, and oil quality. The press had an average OEE of 73% for coconuts and 70% for groundnuts after 12 min of pressing. The oil expression efficiency was characterized by three main stages namely delayed, rapid, and retarded. The power consumption was affected greatly by the pressing time, with power consumption increasing with an increase in the pressing time. The specific energy consumption was found to increase significantly after 8 min of pressing and correlated with the compaction of the cake, which resulted in more power being required to express the entrapped oil. The expressed oil was fresh, free from foots, and of high quality with an average moisture content of 0.015% for coconut oil and 0.019% for groundnut. Analyses showed that the viscosities were 42.1 MPa s (coconut oil) and 59.1 MPa s (groundnut oil), at 25 °C. Overall, the press performed well and was comparable in performance to other types of presses.     

Proximate composition, extraction, characterization and comparative assessment of coconut (Cocos nucifera) and melon (Colocynthis citrullus) seeds and seed oils

Proximate composition, extraction, characterization and comparative assessment of Cocos nucifera and Colocynthis citrullus seeds and seed oils were evaluated in this work using standard analytical techniques. The results showed the percentage (%) moisture, crude fibre, ash, crude protein, lipids and total carbohydrate contents of the seeds as 7.51 and 4.27, 7.70 and 5.51, 1.02 and 2.94, 10.57 and 11.67, 47.80 and 50.42 and 32.84 and 29.47 while the calorific values were 553.99 and 567.32 Kcal/100 g for C. nucifera and C. citrullus, respectively. The two seed oils were odourless and at room temperature (30 degrees C) liquids, with a pale yellow to yellowish colouration. Lipid indices of the seed oils indicated the Acid Values (AV) as 2.06-6.36 mg NaOH g(-1) and 2.99-6.17 mg NaOH g(-1), Free Fatty Acids (FFA) as 1.03-3.18 and 1.49-3.09%, Saponification Values (SV) as 252.44-257.59 and 196.82-201.03 mg KOH g(-1), Iodine Values (IV) as 9.73-10.99 and 110.93-111.46 mg of I2 g(-1) of oil and Peroxide Values (PV) as 0.21-0.21 and 1.53-2.72 mg O2 kg(-1) for soxhlet-mechanical extracted C. nucifera and C. citrullus seed oils, respectively. The studied characteristics of the oil extracts in most cases compared favourably with most conventional vegetable oils sold in the Nigeria markets; however, there were some observed levels of significant differences in the values at p < or = 0.05. These results suggest that the seeds examined may be nutritionally potent and also viable sources of seed oils judging by their oil yield. The data also showed that the seed oils were edible inferring from their low AV and their corresponding low FFA contents. Industrially, the results revealed the seed oils to have great potentials in soap manufacturing industries because of their high SV. They were also shown to be non-drying due to their low IV which also suggested that the oils contain few unsaturated bonds and therefore have low susceptibility to oxidative rancidity and deterioration as confirmed by their low PV which also serves as indicators of the presence or high levels of anti-oxidants in the oils.     

Composition and oxidative stability of crude oil extracts of corn germ and distillers grains

The fatty acid composition, Acid Value, and the content and composition of tocopherols, tocotrienols, carotenoids, phytosterols, and steryl ferulates were determined in corn germ oil and four post-fermentation corn oils from the ethanol dry grind process. The oxidative stability index at 110 °C was determined for the five oils, and four oils were compared for their stability during storage at 40 °C as determined by peroxide value and hexanal content. The fatty acid composition of all five oils was typical for corn oil. The Acid Value (and percentage of free fatty acids) was highest (28.3 mg KOH/g oil) in corn oil extracted centrifugally from a conventional dry grind ethanol processing facility and for oil extracted, using hexane, from distillers dried grains with solubles (DDGS) from a raw starch ethanol processing facility (20.8 mg KOH/g oil). Acid Value was lowest in two oils extracted centrifugally from thin stillage in a raw starch ethanol facility (5.7 and 6.9 mg KOH/g oil). Tocopherols were highest in corn germ oil (∼1400 μg/g), but tocotrienols, phytosterols, steryl ferulates, and carotenoids were higher in all of the post-fermentation corn oils. Hexane extracted oil from DDGS was the most oxidatively stable as evaluated by OSI and storage test at 40 °C, followed by centrifugally extracted thin stillage oil from the raw starch ethanol process, and centrifugally extracted thin stillage oil from the conventional dry grind ethanol process. Corn germ oil was the least oxidatively stable. When stored at room temperature, the peroxide value of centrifugally extracted thin stillage oil from the raw starch ethanol process did not significantly increase until after six weeks of storage, and was less than 2.0 mequiv. peroxide/kg oil after three months of storage. These results indicate that post-fermentation corn oils have higher content of valuable functional lipids than corn germ oil. Some of these functional lipids have antioxidant activity which increases the oxidative stability of the post-fermentation oils.     

Frying Stability of Moringa stenopetala Seed Oil

The frying performance of Moringa stenopetala seed oil (extracted with cold press or n-hexane) was studied especially as regards repeated frying operations. The oils were used for intermittent frying of potato slices and cod filets at a temperature of 175 °C for 5 consecutive days (5 fryings per day). The chemical changes occurring in oils were evaluated. Free fatty acid content, polar compounds, colour and viscosity of the oils all increased, whereas the iodine value, smoke point, polyunsaturated fatty acid content, induction period and tocopherol content decreased. The effect of the oil on the organoleptic quality of these fried foods and the theoretical number of frying operations possible before having to discard the oil was also determined. The analytical and sensory data showed that the lowest deterioration occurred in cold press produced oil.