【作者】 刘昌盛；

【导师】 黄凤洪；

【作者基本信息】 中国农业科学院 ， 农产品质量与食物安全， 2012， 博士

【摘要】 目前我国工业生产的冷榨油，未经精炼则很难达到食用标准；而传统精炼技术是以化学精炼为主，存在能耗高、炼耗高、品质低等问题，不适用于其适度精炼。针对上述存在问题，本研究以冷榨菜籽油（Cold-pressed rapeseed oils, CROs）为研究对象，拟研究开发一种适用于CROs的低温清洁适度精炼技术，通过研究制备出的磷脂（Phospholipids, PLS）吸附剂和游离脂肪酸（Free fattyacids, FFA）吸附剂，分别吸附脱除PLS和FFA；并对CROs的关键特性进行剖析，为进一步改善CROs品质及开发以冷榨油为基料的深加工产品提供理论依据和支撑。具体研究结果如下：1、以钙基蒙脱石为原料，将其钠化制备成固体脱磷剂（Solid dephosphorization agent, SDPA），采用电镜扫描、X射线衍射和热重分析等手段对其进行微结构分析；重点研究SDPA对PLS的吸附行为。研究结果表明，SDPA对PLS的吸附是属于优惠吸附，Freundlich模型能够较好的拟合其静态吸附过程；同时拟二级吸附动力学模型适用于描述其吸附动力学特性；另外，此吸附为吸热且自发进行的过程；吸附机理为：SDPA提供了强路易斯酸反应位点，与PLS分子基团上的强路易斯碱进行了配位结合，形成稳定的路易斯酸碱配合物。2、以纤维素基材料制备了纤维素基固体脱酸剂（Cellulose-based deacidfication adsorbent, CDA），着重分析CDA对FFA的吸附行为。研究结果表明，CDA对FFA的吸附是属于优惠吸附，Langmuir吸附模型能够较好的拟合其静态吸附过程；同时拟二级吸附动力学模型适用于描述其吸附动力学特性；另外，此吸附是放热且自发进行的过程；吸附机理为：CDA表面的纤维素碱、活化羟基能与FFA进行吸附中和反应，生成纤维素脂盐，其连接在纤维素长链上，通过分离可脱除FFA。3、以CROs为原料，进行低温精炼工艺技术研究，研究结果表明，CROs的精炼得率为98.05%，质量达到三级压榨油标准；其总生育酚、总甾醇和总酚的保留率分别为90.1%、85.4%和88.8%；与传统技术相比，新技术提高了精炼得率，减低了精炼能耗和成本，同时有效减少了三废排放。4、采用顶空-固相微萃取、气相色谱-质谱、嗅觉检测器联用技术系统分析CROs的挥发性风味物质，结果表明风味物质主要由硫甙降解产物、醛、醇、烷烃以及呋喃类化合物等组成，其中硫甙降解产物相对含量占60%以上，主要包括1-丁烯基-异硫氰酸酯、甲基丙烯氰和2-甲基-3-丁烯腈。微波预处理油菜籽，使风味物质中硫甙降解产物以热降解为主，并产生吡嗪化合物。感官分析表明，CROs的风味主要体现为Seed-like、woody、astringent和bitter特性；LRT对CROs的感官风味无显著影响（P>0.01）；微波预处理促使CROs产生愉快的坚果味和烤香味。5、系统的研究了CROs流变特性，结果表明CROs属于剪切变稀的非牛顿流体，而当剪切速率大于5s^-1时，CROs表现为牛顿流体行为；甘油酯的碳链长度和温度是影响CROs的粘度、损耗模量（G’’）、塑性稠度系数（ηp）和屈服应力（τo）的主要因素；粘度随芥酸含量增加而提高，而粘度、G’’和ηp值随着温度升高而降低；而在相同脂肪酸组成下，粘度差异取决于其所含微量成分含量，且微量成分含量与τo存在正相关性。另外，LRT对CROs的粘度无显著影响（P>0.01）。更多还原

【Abstract】 It is hard for the cold-pressed oils produced in the industry scale to meet the food oil standard inChina without the treatment of refining. However, the traditional refining technology is based on thechemical refining process with long time and high temperature, which makes high energy consumption,loss of oil and nutrients, and residues of harmful ingredients. The chemical refining is obviouslyunsuitable to the cold-pressed oils. The objective of this paper is to develop a low-temperature refiningtechnology for cold-pressed rapeseed oils （CROs）. The present study evaluated the effects of soliddephosphorization agent （SDPA） and cellulose-based deacidfication agent （CDA） on the removal ofphospholipids （PLS） and free fatty acids （FFA） respectively, and also the key characteristics of CROswere investigated. The main results of the paper are as follow.1. SDPA was prepared with calcium montmorillonite and analyzed with electron microscopescanner, X-ray diffraction and thermal gravimetric analyzer. The behavior of PLS adsorption on SDPAwas investigated. The results showed that the PLS adsorption process was a favorable adsorption, and awell fitted Freundlich equation was obtained for the adsorption isotherm. The PLS adsorption kineticscould be well described by the pseudo-second order kinetics model. Moreover, the adsorption was anexothermic and spontaneous process, and PLS could be adsorped on SDPA under a wide temperaturerange. The mechanism of PLS adsorption on SDPA was concluded as follows: the strong Lewis acidreactive sites of SDPA combined with the Lewis base groups of PLS into the Lewis acid-base complexesby forming coordination bonds.2. CDA was prepared with a kind of cellulose-based material. The behavior of FFA adsorption onCDA was majorly analyzed. The results showed that the FFA adsorption process was a favorableadsorption, and the Langmuir equation was suitable for the adsorption isotherm. The FFA adsorptionkinetics could be also well described by the pseudo-second order kinetics model. In addition, theadsorption was an endothermic and spontaneous process, and FFA could be adsorped on CDA under awide range of temperature. The mechanism of FFA adsorption on CDA was concluded as follows: thealkali cellulose and activated hydroxyl of the surface of CDA could adsort FFA and form the lipid salt,which would be attached to the surface of CDA.3. A research of low-temperature refining technology （LRT） was carried out with CROs. The effectsof LRT on the quality of CROs and the economic and technical performance were evaluated. The resultsshowed that the CROs yield of refining was98.05%. Moreover, qualities of CROs meet the nationalNO.3standard of edible rapeseed oils, and the retention rate of total tocoperols, total phytosterals andtotal phenol were90.1%、85.4%and88.8%. LRT improves the refining yield, and also reduces thepower consumption, cost and waste emissions of refining, compared with the traditional refiningtechnology.4. Volatile flavor components （VFC） of CROs were analyzed with head-space solid-phasemicroextraction, gas chromatograph-mass spectrometer and olfactory detection port. The results showedthat VFC were composed of glucosinolate degradation products （GSDP）, aldehydes, alcohols, hydrocarbons and furans. The relative content of GSDP was more than60%including1-butene-4-isothiocyanate, methallyl cyanide and2-methyl-3-butenenitrile. Morever, VFC ofmicrowave-pretreatment cold-pressed rapeseed oil of low erucic （M-LCRO） were investigated, whichconsisted of GSDP, aldehydes, alcohols, and pyrazine. GSDP were derived from thermal degradation.Compared with CROs,2,5-dimethyl pyrazine and2-ethyl-3,5-dimethyl pyrazine were generated inM-LCRO. The sensory analysis results showed that flavor of CROs majorly reflected seed-like, woody,astringent and bitter, and the most intense flavor was seed-like. There was no significant effect for LRTon the sensory of CROs （P>0.01）. As for M-LCRO, it presented a pleasant nutty and roasted flavor.5. The rheological properties of CROs were investigated. The results showed that CROs behave as anon-Newtonian fluid of shear-thinning. CROs indicated a Newtonian behavior as the shear rates weregreater than5s^-1. The chain length of fatty acids of glycerides and temperature were important factors onaffecting viscosities, loss modulus （G’’）, plastic consistency coefficients （ηp） and yield stress （τo）values of CROs. The viscosities and G’’ of CROs were improved with an increase in the erucic acidcontents. Additionally, viscosities, G’’ and ηpof CROs decreased with the enhancement of temperature.Minor components could be the contributing factors for differences of viscosities of CROs, and thevalues of ηpof CROs were positively correlated with the level of Minor components. Furthermore,there was no significant effect for LRT on viscosities of CROs（P>0.01）.更多还原