Direct determination of the total fat content of butter and edible oil emulsions — an international collaborative study

A standard operating procedure for the direct determination of fat in butter and edible oil products involved the extraction of the fat from the sample, separation of the solvent–fat phase from the serum phase and transfer of the solvent–fat phase to a fat-collecting vessel. The solvent was removed by distillation or evaporation and the mass of extracted matter was determined gravimetrically. This method was studied collaboratively involving 13 laboratories and eight samples to determine precision estimates. Estimates of repeatability and reproducibility were 0.23 g per 100 g and 0.45 g per 100 g, respectively. The method is recommended for adoption as an international reference method.     

Effect of pretreatment with microwaves on oxidative stability and nutraceuticals content of oil from rapeseed

Demand for oil extracted by cold press, such as rapeseed oil, is increasing, but oil extraction yield, and nutraceuticals content are lower for cold pressed oil, compared with oil extracted by solvent. In this study, rapeseed was treated with microwaves, to investigate the possibility of enhancing oil extraction yield, oxidative stability and nutraceuticals content. Rapeseed was pretreated with microwaves for two different times (2 min and 4 min) and oil was then extracted with a press. To compare the results, oil was also extracted from untreated rapeseed by solvent and press. Results showed that solvent-extracted oil had the highest phytosterol content. Microwave pretreatment of rapeseed can increase the oil extraction yield (by 10%), phytosterols (by 15%) and tocopherols (by 55%) of the oil extracted by press. Oil extracted from untreated rapeseed by press had the lowest oxidative stability (1 h); this was increased to 8 h by pretreatment of rapeseed with microwaves. Therefore, from the obtained results, it is advisable to treat rapeseed with microwaves before extraction by oil press, because it gives a relatively good recovery of oil, with a high amount of nutraceuticals, and can produce oil with a longer shelf life and enhanced value.     

The determination of oil and moisture contents in commercial rapeseed samples,the former by solvent extraction

Some protocols based on standard methods for the determination of oil in rapeseed by solvent extraction are compared. Test portions of whole seed give unacceptably poor repeatability in results and ground samples should be used for analysis. Moisture content of rapeseed can equally well be determined on ground as on whole seed. The standard methods require modification to take account of these findings.     

精炼工艺对菜籽油流变特性的影响

以菜籽毛油为原料,分析了脱胶、脱酸、脱色和脱臭（四脱精炼）对菜籽油流变特性以及品质的影响。研究结果表明,四脱精炼对菜籽油的脂肪酸组成和折光指数无显著影响;在恒温下,随着剪切速率的增加,菜籽油的粘度先逐渐减小再趋于稳定,即菜籽油是由非牛顿流体逐渐向牛顿流体转化;同时在大范围的剪切速率下,剪切应力与剪切速率呈近线性关系,菜籽油为牛顿流体;精炼所导致的菜籽油粘度差别与微量成分相关,并且精炼可以降低菜籽油的屈服应力值;Herschel-Bulkley的简化方程τxy=τo＋K（dVx/dY）或者Bingham方程相对适用于表征菜籽油在四脱精炼过程中的流变特性。     

浊度仪法快速测定菜籽油中蜡质含量

为了适应菜籽油中蜡质含量快速测定的要求,根据植物油中的蜡质在低温时会结晶析出,引起植物油浊度变化,利用浊度仪建立了菜籽油中蜡质含量的快速测定方法。考察了溶剂种类、溶剂与油的体积比(溶剂比)、冷却时间对菜籽油中蜡质含量测定的影响。结果表明:以丙酮为溶剂、溶剂比为1∶1、冷却时间为30 min,在蜡质含量为0~250 mg/kg时,所建立方法的线性方程为Y=0.078 7X-0.036 5,相关系数R2=0.999,加标回收率为87.84%~110.42%,相对标准偏差(RSD)为1.13%~2.89%。该方法具有良好的准确度和可行性,数据分析简单,对操作人员的专业要求不高,适合工厂蜡质含量的监控要求。     

加工工艺对菜籽油主要挥发性风味成分的影响

采用固相微萃取（Solid Phase Microextraction,SPME）方法顶空萃取富集预榨菜籽毛油、浸出菜籽毛油、一级菜籽油、冷榨菜籽油和脱皮冷榨菜籽油中的挥发性成分,经气相色谱-质谱联用仪（Gas Chromatography-Mass Spectrometry,GC-MS）检测和初步分析发现,硫甙降解产物、氧化挥发物（醛、醇、烃、酮等）、杂环类物质是构成菜籽油的主要挥发性风味成分;2-甲代-1-丙烯基-氰、5-己腈、1-丁烯基-异硫氰酸酯、苯基丙氰、2-苯基乙基异硫氰酸酯是主要硫甙降解产物;反2-反4-庚二烯醛、反2-反4-癸二烯醛、4-羟基-3,5-二甲氧基苯甲醛、壬醛等醛类物质是氧化挥发物中的主要成分。加工工艺对菜籽油风味影响显著,经高温蒸炒、压榨获得的预榨毛油中杂环类物质种类和相对含量明显高于其它菜籽油。毛油经脱胶、脱酸、脱色、脱臭、脱水等处理后,一级油中产生的醛、醇、酮、烃等氧化挥发物种类增多,相对含量提高;在一级油中未检测到硫甙降解产物。     

Functional properties of butter oil made from bovine milk with experimentally altered fat composition

Modification of milk fat composition might be desirable to alter manufacturing characteristics or produce low saturated fat dairy products that more closely meet consumer dietary preferences. The aim of this research was to evaluate functional properties of butter oil obtained from milks with fat composition modified by altering the profile of long-chain fatty acids (FA) absorbed from the small intestine of cows. A control and 5 mixtures of long-chain free FA were infused into the abomasum of lactating dairy cows in a 6 × 6 Latin square design with 21-d periods. Treatments were 1) control (no FA infused), 2) mostly saturated FA (C₁₆:C₁₈ = 0.72), 3) low-linoleic palm FA (C₁₆:C₁₈ = 0.85), 4) palm FA (C₁₆:C₁₈ = 0.72), 5) soy FA (C₁₆:C₁₈ = 0.10), and 6) high-palmitic soy FA (C₁₆:C₁₈ = 0.68). All treatments included meat solubles and Tween 80 as emulsifiers. Solid fat content (from 0 to 40°C), melting point, and force at fracture were determined in butter oil. Milk fat from cows infused with palm FA (treatment 4) exhibited functionality equal to or better than control butter oil. Infusion with palm FA increased amounts of triglyceride (TG) fractions with 48, 52, and 54 carbon numbers but decreased TG with 32, 34, 36, and 42 carbon numbers. Infusion with soy FA increased TG with 26, 38, 40, 52, and 54 carbon numbers but decreased TG with 34, 42, and 46 carbons. Infusion of the mostly saturated FA increased TG with 38, 50, 52, and 54 carbon numbers but decreased TG with 32, 34, and 42 carbon numbers. These TG groups were consistently correlated with functional properties of butter oils from different treatments. The content of palmitic acid is important for maintaining functionality in the presence of increased polyunsaturated FA. The composition of milk fat may be able to be optimized through nutritional manipulation of diets for dairy cows if the optimal composition of FA and TG is defined for a particular dairy product.     

补喂油菜籽对放牧牦牛乳的影响

研究了补饲经脱毒处理的油菜籽在青草期和枯黄期对放牧牦牛乳的影响。结果表明,对照组(未补饲油菜籽)在青草期和枯黄期中的乳脂率分别是6.58%±0.52%和7.18%±1.04%,与对照组相比,补饲100g/d油菜籽组的乳脂率在青草期和枯黄期都不受影响,补饲200g/d油菜籽组的乳脂率在青草期和枯黄期时分别为5.81%±0.62%和6.53%±0.86%,乳脂率显著降低(P<0.05);在青草期和枯黄期,补饲油菜籽对各试验组的乳产量、乳蛋白率和乳糖率无显著影响,而枯黄期补饲200g/d油菜籽组,乳干物质含量显著降低。     

基于微波预处理油菜籽的压榨油和浸出油理化品质比较

微波预处理油菜籽可显著提高压榨出油率,但压榨后的饼粕中仍残留油脂,可采用浸出法提取饼中残油。为比较压榨油和浸出油的主要理化品质,在2450MHz、800W的微波条件下,分别对油菜籽预处理0～7min,冷却至室温后压榨制油,继而对饼粕中残油用正己烷萃取。结果表明,微波处理时间、压榨和浸出的制油方式对菜籽油酸价、过氧化值、p-茴香胺值、水分含量均有显著影响（P〈0.05）。压榨油和浸出油的酸价、p-茴香胺值随微波时间的延长而增加,过氧化值呈先增加后减少的趋势,浸出油酸价、过氧化值和p-茴香胺值高于压榨油。压榨油水分含量随微波时间的延长而增加,而浸出油的则减少,压榨油水分含量高于浸出油。压榨油和浸出油的色泽（罗维朋比色）随微波时间的延长逐渐变深,浸出油色泽更深;加热试验（至280℃）中压榨油无析出物,而浸出油产生絮状析出物。由此可见基于微波预处理油菜籽的压榨油仅需水洗、过滤或离心分离即可满足国家标准,浸出油则需要进行脱胶、脱酸、脱色等精炼处理。     

Ultrasonic bleaching of rapeseed oil: Effects of bleaching conditions and underlying mechanisms

An ultrasonic bleaching process for rapeseed oil was studied by monitoring the removal of oil-containing pigments spectrophotometrically at 446 nm in varied bleaching conditions. When low-power ultrasound was used, bleaching was resulted from pigment adsorption by adsorbents, among which bentonite decreased the A₄₄₆ the most from 1.82 to 0.65. Ultrasound enhanced the absorption rate rather than the total absorption capacity. When high-power ultrasound was used, bleaching took place even in the absence of adsorbent as evidenced by the decease of A₄₄₆ to 0.74, possibly due to the effects of combining heat and sonochemical degradation of pigments. The overall bleaching effects were enhanced with the increase of ultrasound power, sonication time and treatment temperature. The content of primary oxidation products in oils increased after sonication, whereas the content of secondary oxidation products remained constant. Due to its multiple mechanisms, ultrasonic bleaching may be a good alternative to the adsorption-based bleaching method.     

非脂乳固体和脂肪含量影响酸牛乳粘度的研究

通过调整酸牛奶配方中非脂乳固体和脂肪的含量，使酸牛乳粘稠度发生变化，找出它们之间的关系，确定最佳粘稠度的配方。     

煎炸菜籽油的脂肪酸组成与品质相关性的研究

在150、180、210℃3个温度水平下,用菜籽油煎炸土豆,分别取4、8、12、16、20、24、28、32 h的油样,检测其脂肪酸组成及波长232 nm处紫外特征吸收峰值(K232)和波长270 nm处紫外特征吸收峰值(K270)。以K232和K270表征油脂的品质,利用SPSS软件分析饱和脂肪酸(SFA)、单不饱和脂肪酸(MUFA)和多不饱和脂肪酸(PUFA)的含量与油脂品质的相关性。结果表明:SFA、PUFA分别与K232、K270呈线性相关,MUFA与K232、K270分别呈多项式相关,SFA、MUFA、PUFA3类脂肪酸都与K232、K270显著相关(P0.01),因此也可利用SFA、MUFA、PUFA的含量来表征菜籽油的品质。     

Dissimilarity of the oxidations of rapeseed and butter oil triacylglycerols and their mixtures in the absence of tocopherols

Although fatty acid composition is the most important attribute used to control oxidation stability, all edible oils are affected by lipid oxidation irrespective of whether they are highly unsaturated or not. The aim of the study was to compare the oxidation of rapeseed oil (RO) and butter oil (BO) triacylglycerols (TAGs) and their mixtures containing 10% or 20% of the other. Oxidation of the TAGs at 40°C was followed by formation of primary and secondary products. Statistical methods were used to interpret the data. The RO and BO TAGs and their mixtures began to oxidise without any induction periods. In the RO TAGs more hydroperoxides and p‐anisidine reactive compounds were formed than in the BO TAGs. The BO TAGs oxidised more than would be expected by their fatty acid composition. High susceptibility of BO TAGs to oxidation was caused by the easy breakdown of their hydroperoxides. Heptadienal and heptenal were specific products of oxidised RO TAGs and heptanal and nonenal of oxidised BO TAGs. Mixtures of RO and BO TAGs behaved according to which was dominant in the mixture. However, as little as 10% of RO or BO TAG introduced its specific oxidation products to the mixture. © 1999 Society of Chemical Industry     

Physical and sensory characteristics of pork sausages from enzymatically modified blends of lard and rapeseed oil during storage

Physical and sensory characteristic of pork sausages produced from enzymatic interesterified blends of lard and rapeseed oil during storage were evaluated. All three enzymatic interesterified blends (IE90, IE70 and IE50) had ratios of unsaturated to saturated fatty acids within the range of 1.47–2.84 which is favourable for cardiovascular disease risk reduction. Blends of IE90 and IE70 were found to have suitable solid fat content, melting and crystallization profile suitable for sausages production. Sausages were produced from blends of IE90 and IE70 with different muscle types (musculus longissimus dorsi and musculus sternomandibularis) and processing conditions such as cooling rates and final processing temperature. Cooling rate was found to have no significant (P > 0.05) effect on hardness of the sausages throughout storage. Both musculus longissimus dorsi and high final processing temperature of 20 °C increased the hardness of the sausages during storage. In terms of fat particle size distribution, it was found that sausages IE70 had significantly (P < 0.05) lower amount of small fat particles (<4 μm) and higher amount of big fat particles (4–500 μm). This is in agreement with the findings on softer texture of sausages IE70. All the sausages produced from interesterified blends of lard and rapeseed oil had no apparent fat excretion and were rated as having acceptable sensory attributes as compared to reference sausage which was produced from pure lard.     

The advantages of solid fat content determination in cocoa butter and cocoa butter equivalents by the Karlshamns method

This paper describes the preparation of samples and the evaluation techniques applied to determine the Solid Fat Content (SFC) by means of pulsed nuclear magnetic resonance (NMR) in confectionery fats characterized by distinct polymorphism (cocoa butter, cocoa butter equivalents and their mixtures). Due to the deviation of SFC values in certain softer cocoa butter equivalents at the temperature of 20 °C, an internal method devised at Karlshamns Oils & Fats AB is applied as well. When compared to the official IUPAC 2.150 (b) method, Karlshamns' method involves a lower temperature and a prolonged period of time at the stage of the final SFC stabilization in the pre-treatment of fat samples. The calculation of SFC in the analysed samples for the purposes of this paper was carried out by employing both methods (the indirect method and a serial procedure). The results are presented graphically. Differences were reflected in the SFC of the fats and their mixtures that were under observation depending on the method and temperatures applied. The obtained results indicated a considerable advantage of employing the Karlshamns method since the results yielded by this method are more lucid. Moreover, the behaviour of fats in the production process can be more easily predicted on the basis of these results.     

猪油和单甘酯含量对菜籽油凝胶油性质的影响研究

考察了将猪油与菜籽油按一定比例混合,并以单甘酯为凝胶剂形成的混合凝胶油的性质,探讨猪油和菜籽油质量比及单甘酯含量对混合凝胶油性质的影响,以制备出低饱和脂肪酸、能够更好地部分替代猪油的菜籽油混合凝胶油。测定了混合凝胶油的流变性质、质构性质、固体脂肪含量以及热力学性质。结果表明,当猪油和菜籽油质量比为5∶5,加入8%的单甘酯时,混合凝胶油与菜籽油凝胶油相比凝胶性质更好,在常温下固体脂肪含量更接近猪油。     

制油工艺对菜籽油微量成分和氧化稳定性的影响

以不同制油工艺制得的菜籽油为原料,比较研究了菜籽油的酸值、过氧化值、脂肪酸和甘三酯的组成及微量营养成分。结果表明:制油工艺对菜籽油的脂肪酸和甘三酯组成无显著性影响;水酶法制得菜籽油的酸值(KOH)相对较高,为0.995 mg/g,但富含β-胡萝卜素、植物多酚,含量分别为5.40 mg/kg和152.08 mg/kg;浸出菜籽毛油富含生育酚和植物甾醇,含量分别为833.74 mg/kg和6 607.35 mg/kg;精炼菜籽油的酸值(KOH)最低,仅为0.233 mg/g,但精炼菜籽油的微量营养成分相对较少。分别以氧化诱导时间和DPPH自由基清除能力为指标,评价了不同制油工艺制得菜籽油的氧化稳定性,结果发现5种菜籽油的氧化稳定性大小是:水酶法菜籽油最强,精炼菜籽油最弱,而浸出菜籽毛油、热榨菜籽油和冷榨菜籽油介于其间,这一性质和油中的植物多酚和β-胡萝卜素含量呈显著正相关。     

高含油量油菜种子和果皮油份积累及主要脂肪酸的动态变化

以高含油量油菜品系为材料,研究角果发育过程中种子和果皮油份积累与主要脂肪酸的动态变化。结果表明：高含油量品种在角果发育早期油份的合成与积累较为缓慢,开花后20d种子含油率仅占成熟种子油份含量的8．35％～12．32％,角果发育中期是油份含量增加最快的时期,开花后40d种子含油率占成熟种子油份含量的72．89％。94．73％,籽粒成熟时油份含量达到最大值。果皮的油份积累与种子相反,随角果发育油份含量依次下降,两者呈极显著负相关,相关系数为-0．95。种子和果皮的二十碳烯酸、芥酸合成规律明显不同。种子的7种主要脂肪酸组成中芥酸和二十碳烯酸与16碳、18碳脂肪酸含量均呈负相关,亚麻酸和亚油酸与棕榈酸、硬脂酸和亚油酸含量均呈正相关,与油酸含量H2和H27为正相关,H1和H28为负相关。而油酸与其它脂肪酸的相关关系较为复杂,与棕榈酸、硬脂酸和亚油酸、亚麻酸的相关关系有正相关,也有负相关,可见油酸的合成与积累不仅与棕榈酸、硬脂酸有关,还会影响亚油酸和亚麻酸的含量,这是创新油菜高油酸材料的基础。     

Influence of fat content and emulsifier type on the rheological properties of cake batter

The effects of fat content and emulsifier type on the rheological properties of cake batter have been investigated by using a parallel-plate rheometer. The apparent viscosity of cake batter with five different fat concentrations (0, 12.5, 25, 37.5, and 50%) and two types of emulsifier, namely Purawave and Lecigran, was studied as a function of the shear rate. In addition, the time dependency of different cake formulations was investigated. It was found that cake batter with different fat concentrations and emulsifier types exhibited shear thinning and time-independent behavior. Experimental data provided a good fit for the power law model. The increase in fat content and addition of emulsifier caused a decrease in the apparent viscosity. The flow behavior index was not found to be dependent on the composition of cake batter.