Adsorption of carotenes and phosphorus from palm oil onto acid activated bleaching earth: Equilibrium,kinetics and thermodynamics

In this work, the adsorption of carotenes and phosphorus from crude palm oil onto acid activated bleaching earth was investigated under bleaching conditions, i.e. high temperature (90, 105 and 115 °C) and low pressure (less than 50 mbar). Bleaching earth was added to palm oil in a range of 0.5–3.0 wt%. Results presented in this work suggest that adsorption of β-carotene increases with temperature, while phosphorus adsorption was less affected. Both the pseudo-first-order and the pseudo-second-order kinetic model describe efficiently the β-carotene experimental data. Intra-particle diffusion is involved in β-carotene adsorption mechanism, although it is not the sole rate limiting step in the adsorption onto acid activated bleaching earth. Phosphorus adsorption was too fast resulting in a lack of kinetic data. The equilibrium data were described better by Langmuir and Freundlich models, for β-carotene and phosphorus, respectively. A multi-component Freundlich type isotherm was tested. Its competition coefficients were too low, and it assumed the same form as the monocomponent Freundlich. A thermodynamic study demonstrated that β-carotene and phosphorus adsorption is spontaneous, endothermic and an entropy-driven process. Isosteric heat values suggest that the interactions between adsorbate and adsorbent are heterogeneous.     

高水分蒸坯对浸出棉籽毛油品质的影响

在实验室模拟高水分蒸坯过程,研究蒸坯水分、蒸坯温度、蒸坯时间等因素对浸出棉籽毛油磷脂和游离棉酚含量的影响,并采用正交试验对高水分蒸坯工艺进行优化.结果表明,蒸坯水分20％,蒸坯温度95℃,蒸坯时间65 min,可以将棉籽毛油中磷脂含量降至0.87％,游离棉酚含量降至0.075％,有效改善了浸出棉籽毛油的品质.     

两种不同烹饪方式对亚麻籽油品质的影响

以亚麻籽油烹饪土豆,研究比较煎、炒两种传统中式菜肴烹饪方式下的亚麻籽油品质差异,探讨不同烹饪方式对亚麻籽油脂肪酸组成及理化指标的影响。结果表明:炒和煎均会导致亚麻籽油中α-亚麻酸含量下降,且炒较煎下降得更多;炒土豆亚麻籽油的过氧化值、p-茴香胺值和总极性物质含量均显著高于煎土豆亚麻籽油,且炒对总极性物质增量的贡献主要为聚合物的增加。因此,当用亚麻籽油烹饪土豆时,煎比炒更合适。     

烹饪方式对胡麻油不饱和脂肪酸的影响

通过设计不同温度下、不同加热时间、冷锅冷油及热锅冷油试验,分析其对胡麻油不饱和脂肪酸的影响。结果表明:不同加热温度、时间对胡麻油不饱和脂肪酸影响显著,随着加热温度的升高,不饱和脂肪酸含量有下降趋势,相同加热温度下时间越长,不饱和脂肪酸含量下降越快。冷锅冷油和热锅冷油的烹饪方式对胡麻油不饱和脂肪酸影响差异不显著,随着加热温度的升高,某未知物质有了显著升高,冷锅比热锅更容易生成该物质且变化明显。加热温度、加热时间与胡麻油不饱和脂肪酸呈负相关性。     

Analysis of a complex mixture of carotenes from oil palm (Elaeis guineensis) fruit extract

A carotene extract from the fruits of the oil palm (Elaeis guineensis) was analysed by HPLC employing a C₃₀ column for better separation efficiency. A multitude of cis-isomers of α-, β- and γ-carotene were separated. Detailed assignment was possible by subjecting pure standards of α-, β- and γ-carotene to isomerisation and comparing spectral data and order of elution to literature data. α- and β-carotene were found to be the most abundant carotenoids comprising 12.3% and 17.9%, respectively, of a (roughly) 30% oil suspension of oil palm carotenes in vegetable oil. A large proportion (about 40%) of α- and β-carotene was in the form of cis-isomers. The γ-carotene content was found to be 0.38% and other carotenes like phytoene, phytofluene, ζ-carotene, lycopene and possibly β-zeacarotene were found as well but were not quantified.     

Antioxidant activity of palm oil carotenes in organic solution: effects of structure and chemical reactivity

The antioxidant effectiveness of palm oil α-carotene and comparison with β-carotene in organic solution containing egg-yolk phosphatidycholine (EYPC) in the presence of lipid soluble 2,2¹-azobis (2,4-dimethyl valeronitrile) (AMVN)-generated peroxyl radicals was investigated by measuring the formation of phosphatidyl choline hydroperoxide (PCOOH) and thiobarbituricacid reacting substances (TBARS). Lutein and zeaxanthin (xanthophylls), similar to α and β carotenes, respectively, but differing in containing hydroxyl groups on the two rings (3,3¹-diol), were also included in the investigation. The carotenes were more rapidly oxidised than the xanthophylls in the solution. The initial rates of oxidation of the carotenoid tested were 0.39 μM min⁻¹ (α-carotene), 0.44 μM min⁻¹ (β-carotene), 0.30 μM min⁻¹ (lutein) and 0.33 μM min⁻¹ (zeaxanthin). Incubation of EYPC with AMVN at 37°C induced the accumulation of PCOOH at the linear rate of 1.8 μM min⁻¹. Although, all the carotenoids tested at 1 mol % relative to EYPC retarded (p < 0.05) the chain propagation reaction of PCOOH formation α-carotene had the highest activity but this was less than α-tocopherol. α-Tocopherol, α-carotene, β-carotene, lutein and zeaxanthin reduced PCOOH accumulation by 78, 65, 40, 60 and 43%, respectively. AMVN incubated with EYPC for 2 h induced the formation of TBARS compared to the control (p < 0.001). α-Carotene significantly suppressed the TBARS formation by 68% whilst β-carotene, lutein and zeaxanthin elicited 50, 64 and 53% reductions, respectively. α-Tocopherol retarded the TBARS formation by 80%. These results suggest that α-carotene, a carotenoid abundantly present in human diets, especially red palm oil, may better attenuate peroxyl radical-dependent lipid peroxidation than β-carotene in organic solution.     

Effects of different cooking methods on the chemical and physical properties of carrots and green peas

The study was aimed to evaluate the physicochemical effects of three cooking methods i.e. sous-vide (SV), cook-vide (CV) and traditional cooking (TC) on carrots and green peas. SV and CV were performed at 60–90 °C for various time periods (SV: green peas 50–100 min, carrots 90–150 min; CV: green peas 30–70 min, carrots 20–60 min) with respect to peroxidase test. These vegetables were also cooked at atmospheric pressure for 15, 30, 45 and 60 min and the results were compared with those obtained from SV and CV. Antioxidant activity, total phenolic and vitamin C analyses reflected less harm to the green peas in CV as compared to SV and TC. However, carrots were approximately half degraded during SV than in CV and TC as shown by the antioxidant activity. Moreover, total phenolic content of carrots was highly protected when cooked in SV method. The color change values (∆ E) of green peas were slightly lower in TC when compared to CV and SV, while in carrots, they were very close to each other's in all three methods. CV-cooked green peas and carrots provided the highest general acceptance for the sensorial properties. As a conclusion, TC had more adverse effects on the quality characteristics on green peas and carrots.     

粒状粗粒化材料对乳化态餐饮废油的分离效果研究

选取直径为3~4 mm的脱脂核桃粒、PP粒、石英砂为粒状粗粒化材料,探究不同材料对乳化态餐饮废油分离效果的影响。通过对流向、流速、温度、填料高度的控制,得出不同条件下的3种粒状粗粒化材料对乳化态餐饮废油的去除效果。结果表明:采用自下而上流向更加有利于粒状粗粒化材料对乳化态餐饮废油的去除效果;升高温度不利于除油率和CODCr去除率提升,而且呈负相关;提高流速会使除油率和CODCr去除率降低;随着填料高度的增加,除油率和CODCr去除率均呈现出先增加后降低的趋势,在自下而上流向、流速50 L/h、温度40℃、填料床高度20 cm时达到最佳分离效果;粒状粗粒化材料的除油率随着使用时间的延长会逐步降低,采用高速水流反冲洗能够使亲水性粒状粗粒化材料石英砂、脱脂核桃粒恢复良好的除油效果。     

两步法催化潲水油制备生物柴油的研究

采用两步法催化高酸值潲水油制备生物柴油,第一步先用硫酸铁催化潲水油中游离脂肪酸和甲醇酯化生成脂肪酸甲酯(生物柴油),然后再用氢氧化钾催化潲水油中的甘油三酯和甲醇进行酯交换。结果表明,硫酸铁对酯化反应具有很强的催化活性,而且可以回收利用。通过正交试验得到最佳酯化反应参数:硫酸铁用量2%,反应温度95℃,醇油摩尔比10∶1,反应时间4 h,该条件下游离脂肪酸酯化率达97.22%。酯交换条件为:KOH用量1%,反应温度65℃,反应时间1 h,醇油摩尔比6∶1。经过两步催化,产品中总的脂肪酸甲酯(生物柴油)含量达97.02%。该两步催化法具有不产生酸化废水,不需要耐强酸设备,反应时间短,转化率高,同时硫酸铁可以回收重复利用等优点。     

不同来源脂肪酶催化餐厨废油水解实验研究

研究不同来源的脂肪酶催化餐厨废油水解反应制备脂肪酸,通过单因素实验考察了酶用量对酶解率的影响,在此基础上采用正交实验对水解工艺参数酶用量、水解温度、油水比和水解时间进行优化。结果表明:猪胰脂肪酶L3621和假丝酵母脂肪酶LS20在适宜条件下均可实现餐厨废油的高效酶催化水解;L3621最佳水解条件为酶用量700 U/g、水解温度45℃、油水比1∶1.2、水解时间36 h,在此条件下酶解率达94.30%;LS20最佳水解条件为酶用量600 U/g、水解温度40℃、油水比1∶1、水解时间36 h,在此条件下酶解率达96.84%。     

Reduction of mutagenicity of the fumes from cooking oil by degumming treatment

The fume of cooking oil has been reported to increase the risk of respiratory tract cancer. The influence of a degumming treatment of peanut oil on the contents of mutagenic compounds in fumes from heated peanut oil was investigated. The results indicate that the peanut oil prepared from roasted peanut kernels which underwent degumming treatment had a lower free fatty acid (FFA) content and a higher smoke point, was more clear in color, and produced less fumes when heated at smoke point. Moreover, when compared to untreated peanut oil, the mutagenicity of oil fumes of degummed peanut oil toward Salmonella typhimurium TA98 and TA100 was reduced to 81% and 73% (p<0.05), respectively. The degummed peanut oil which was obtained by adding 3% water and heating at 60°C for 20 min produced the least amount of mutagenic fume. The contents of four mutagenic compounds, trans-trans-2,4-decadienal (t-t-2,4-DDE), trans-trans-2,4-nonadienal (t-t-2,4-NDE), trans-2-decenal (t-2-DCA), and trans-2-undecenal (t-2-UDA) in oil fumes of degummed peanut oils were drastically decreased (p<0.05), especially the t-t-2,4-DDE. The results also indicate that the FFA content had a high linear correlation with mutagenicity (r²=0.9978) and content of t-t-2,4-DDE (r²=0.7685). Moreover, there was a correlation (r²=0.7816) between the content and the mutagenicity of t-t-2,4-DDE. The decrease of FFA by degumming might explain the reduction of mutagenic alkenal compounds and mutagenicity of fumes from heated peanut oil.     

废餐饮油酯交换制备生物柴油研究进展

综述了废餐饮油制备生物柴油的几种酯交换方法,重点阐述了碱催化法、酸催化法、酸碱两步法、酶法及无催化剂条件下酯交换制备生物柴油的研究进展,并对存在的问题进行了讨论。     

餐饮废油与食用植物油品质的GC-MS检测

采用气相色谱-质谱联用(GC-MS)法分析餐饮废油特征性脂肪酸组成成分.以合格鲜榨菜籽油、调和油和餐饮废油潲水油、煎炸老油为材料,通过油样的皂化、甲酯化处理后,以毛细管柱DB-5MS作分离柱,用气相色谱一质谱仪分析出脂肪酸组成与含量.结果表明,潲水油、煎炸老油中脂肪酸相对不饱和度(U/R≈1.9)明显小于合格植物油(U/R≈4.4),并在其中检测到了十三烷酸(含量约0.27%)和十七烷酸(含量约6.49%)等奇数碳脂肪酸.     

固体酸碱催化餐饮废油脂制备生物柴油

采用固体酸、碱催化餐饮废油脂制备生物柴油.首先用煅烧后的(NH4>)2>SO4>/Al2>O3>催化甲醇和餐饮废油脂中的游离脂肪酸进行预酯化反应,然后再用煅烧后的Na2CO3/Al2O3催化甲醇和餐饮废油脂中的甘油三酯进行酯交换反应.结果表明,经预酯化的餐饮废油脂在以正己烷为溶剂、溶剂用量为1.5 mL/g(oil)、醇油摩尔比为15:1、反应温度为50℃、反应时间为4 h和催化剂用量为8%的最佳工艺条件下进行酯交换反应.反应转酯率为96.85%.     

食盐添加量对滩羊肉蒸煮损失、嫩度及水分分布的影响

为探究不同食盐添加量对滩羊肉蒸煮损失、嫩度以及水分分布的影响,以滩羊肉为实验材料,借助低场核磁共振技术研究不同食盐添加量处理下滩羊肉的蒸煮损失、剪切力以及水分子T₂弛豫特性。结果表明:随着食盐添加量的增加,滩羊肉的蒸煮损失和剪切力都明显减小（p<0.05）,当食盐添加量大于2.5%时,差异不显著（p>0.05）。LF-NMR检测到了四个明显的水分群,代表肉中的弱结合水、强结合水、不易流动水和自由水四种存在状态。增加食盐添加量,弛豫时间逐渐变短,不易流动水逐渐增多,自由水逐渐减少。核磁成像结果显示,随着食盐添加量的增加图像的亮度依次减弱。相关性分析结果表明,蒸煮损失与T₂₃、T₂₄呈显著正相关（p<0.05）;剪切力与T₂₃、T₂₄峰面积百分比呈显著正相关（p<0.05）,与T₂₃峰面积百分比呈显著负相关（p<0.05）。由此表明,不同食盐添加量处理下滩羊肉的水分分布具有显著地变化。      

食盐添加量对滩羊肉蒸煮损失、嫩度及水分分布的影响

为探究不同食盐添加量对滩羊肉蒸煮损失、嫩度以及水分分布的影响,以滩羊肉为实验材料,借助低场核磁共振技术研究不同食盐添加量处理下滩羊肉的蒸煮损失、剪切力以及水分子T_2弛豫特性。结果表明:随着食盐添加量的增加,滩羊肉的蒸煮损失和剪切力都明显减小(p0.05),当食盐添加量大于2.5%时,差异不显著(p0.05)。LF-NMR检测到了四个明显的水分群,代表肉中的弱结合水、强结合水、不易流动水和自由水四种存在状态。增加食盐添加量,弛豫时间逐渐变短,不易流动水逐渐增多,自由水逐渐减少。核磁成像结果显示,随着食盐添加量的增加图像的亮度依次减弱。相关性分析结果表明,蒸煮损失与T_(23)、T_(24)呈显著正相关(p0.05);剪切力与T_(23)、T_(24)峰面积百分比呈显著正相关(p0.05),与T_(23)峰面积百分比呈显著负相关(p0.05)。由此表明,不同食盐添加量处理下滩羊肉的水分分布具有显著地变化。     

低温真空油炸对半干水产品营养成分和食用油品质的影响

研究了在不同温度、真空度及油炸时间条件下,低温真空油炸对半干水产品(半干马面鱼)水分、蛋白质、脂肪含量的变化情况及食用油的过氧化值、酸价和羰基价随油炸温度和时间以及真空度改变的变化规律。结果显示,真空度是影响半干水产品品质的主要因素,但对油炸过程中油脂的稳定性影响非常小,而油炸温度和油炸时间对油炸产品的品质影响相对较小。大豆食用油的过氧化值、酸价和羰基价随油炸温度的升高和时间的延长出现上升的趋势,但幅度很小。在整个真空油炸实验过程中,大豆食用油具有很好的稳定性。      

解脂耶罗维亚酵母菌利用地沟油联产柠檬酸和胞内油脂

以地沟油为原料,以解脂耶罗维亚酵母菌(Yarrowia lipolytica)为发酵菌株,进行柠檬酸和胞内油脂的同时发酵。结果发现,发酵过程中柠檬酸和胞内油脂同时保持较高产量的最佳发酵条件为:接种量为5×108个细胞/L培养基,碳源质量浓度为80.0 g/L,摇床培养转速为180 r/min。在该条件下,柠檬酸和胞内油脂的产量分别达到33.6 g/L和44.9 g/100 g(细胞干重)。进一步研究发现,Y.lipolytica以地沟油为原料合成柠檬酸和胞内油脂的发酵过程包括3个阶段:细胞生长阶段、油脂合成阶段和柠檬酸合成阶段。地沟油转化为胞内油脂后,其脂肪酸饱和程度降低。     

餐饮废油生物柴油中甘油和硫含量的同步优化

为提高餐饮废油生物柴油的品质,降低其甘油和硫含量,分析了离心、静置、水洗-旋蒸3种方法的脱甘油效果,以及氧化、吸附(活性炭作吸附剂)2种方法的脱硫效果,并对甘油和硫含量进行同步优化研究。结果表明：在3种脱甘油方法中,水洗-旋蒸的脱甘油效果最好;氧化脱硫在将硫化物脱除的同时会导致生物柴油的损失,并降低生物柴油的氧化稳定性,与静置和超声氧化脱硫相比,搅拌氧化脱硫的效果较好,脱硫率和生物柴油损失率分别为28.5%和2.0%;在活性炭用量为2%时,脱硫率较高,为23.8%;水洗-旋蒸可以有效地对生物柴油中甘油和硫同时脱除,脱除后的硫、甘油单酯、游离甘油、总甘油含量分别为9.31 mg/kg、0.182%、0.008%、0.054%,脱除率分别达到11.9%、64.3%、78.9%和68.4%,符合GB 25199—2017附录C中BD100生物柴油标准要求。因此,实际生产中可以采用水洗-旋蒸的方法对生物柴油中的甘油和硫进行同步脱除。     

餐饮废油的回收处理及制皂工艺

以回收油脂的酸值和过氧化值为指标,采用单因素试验和响应面试验优化餐饮废油回收工艺。将回收处理后的餐饮废油进行皂化反应制备透明皂,以透明度为指标优化透明皂的制备工艺,并对制备的透明皂进行综合感官评价。结果表明,餐饮废油的最佳回收工艺条件为：反应温度106.64 ℃,搅拌时间25 min,质量分数为3.5%的过氧化氢溶液用量9.16 mL,吸附剂用量5327%,活性炭与活性白土质量比值40%。在最佳回收工艺条件下,回收油脂的酸值（KOH）为2.15 mg/g,过氧化值为4.50 mmol/kg,符合菜籽原油国家标准。透明皂的最佳制备条件为搅拌速度70 r/min、皂化温度80 ℃、质量分数为30%的氢氧化钠用量12 mL、皂化时间45 min,在此条件下透明皂的透明度为58.2%,综合感官评价结果良好。