Extraction of Phospholipids from Egg Yolk Flakes Using Aqueous Alcohols

Two alcohols, ethanol and butanol, with different water contents were evaluated for phospholipids (PL) sequential extraction from drum dried egg yolk flakes. It showed that butanol was more effective in extracting total yolk lipids compared to ethanol, but the PL in the extract had the same concentration as in the original yolk total lipid. The use of aqueous ethanol of 95 and 75% resulted in lipid extracts with higher PL concentration during the initial stages of the sequential extraction. When ethanol was further diluted to a concentration of 55%, the solvent lost its PL extraction ability, and the total lipid recovery also decreased dramatically. When both the PL purity and recovery were considered, 75% ethanol was the most effective aqueous alcohol for PL extraction and enrichment from the yolk flakes. In the first stage of extraction using such a solvent, 67% of the total PL in the original yolk was recovered in a lipid fraction with a PL purity of 75%. This study identified the optimal ethanol concentration for PL extraction from dried egg yolk. With this information, the best solid:solvent ratio can be designed to extract and enrich the polar lipids from lipid-bearing materials with known moisture content using a renewable or “green” solvent, ethanol.     

Destabilization of Egg Yolk Emulsion After IgY Removal Through Enzymatic Treatments

The objective of this study was to destabilize the protein–lipid complex in egg yolk precipitate obtained after the removal of soluble proteins, referred to as the pellet, through enzymatic treatment for further phospholipids extraction. A combination of proteolytic and lipolytic enzymes was applied to release the lipids from the pellet or weaken the pellet emulsion. Emulsions prepared using Protease P/Lipase AY30, Protease II/Lipase AY30 and Protease M/Lipase AY30 treated pellets had larger oil droplets (78, 65, 56 µm) and higher coalescence rates (51, 41, 35 %) than those of Protex 51FP, pellet, Protex 7L and Protease A with oil droplet size of 20, 18, 15 and 13 µm and coalescence rates of 31, 8, 7.5 and 8 %, respectively. Cream and liquid subnatant fractions obtained after further centrifugation of hydrolysates were subjected to lipid analyses. Over 90 % of phosphatidylcholine (PC) present in the pellet and 80 % of that in the original egg yolk were recovered in the cream from Protease P/Lipase AY30 treatment, while the recovery of PC from the egg yolk was significantly lower in creams from Protex 7L or Protease 51FP treatments (12 and 10 %, respectively). Pellets treated with Protease M, Protex 7L or Protex 51FP in combination with Lipase AY30 led to a significant loss of PC due to the conversion of PC to lysophosphatidylcholine or its degradation. Cream fractions obtained from the study represented a better material for the recovery of PL than intact egg yolk using environmentally-friendly techniques such as supercritical carbon dioxide (SC-CO₂) extraction.     

蛋黄卵磷脂制备工艺及超临界CO_2脱蛋黄油实验研究

对用超临界CO_2萃取技术制备蛋黄卵磷脂的几种典型工艺进行了归纳、分析和比较。根据选择的工艺,对关键设备萃取器料筒进行了改进,通过正交试验,探讨了萃取压力、温度、时间、料筒层数等条件对蛋黄油脱除率的影响规律。     

Encapsulation of Long-Chain n-3 Polyunsaturated Fatty Acids Using Egg Yolk

Egg yolk is well known for its excellent emulsifying property. In this article, egg yolk was used as the encapsulating matrix to prevent the oxidation of n-3 long-chain polyunsaturated fatty acids from fish oil. A 2 × 2 × 5 complete block design with three replications was used. Two levels of fish oil (1% and 5%) and two levels of esterification type (triglycerides or ethyl esters) of eicosapentaenoic/docosahexaenoic fatty acids were used. Time was considered a fixed factor with five levels. Emulsions were prepared by homogenization and stored for up to 4 weeks at 4–6 °C, with weekly sampling. Emulsions were analyzed for particle size and distribution, encapsulation efficiency, and surface oil. The oxidative stability of the emulsions was evaluated before and after cooking at 150–170 °C for 75 s. The addition of triglycerides resulted in a larger average particle size (234 ± 12.4 nm). All emulsions achieved 100% encapsulation efficiency and showed no significant change in the surface oil concentration during storage. After 4 weeks of storage, the concentration of eicosapentaenoic + docosahexaenoic fatty acids in nonencapsulated fish oil triglycerides and ethyl esters decreased by 20.32% and 14.74%, respectively, while the emulsions showed no significant differences. In addition, no peroxide or propanal formation was detected in raw emulsions over the storage period. Propanal formation was negligible in cooked samples, and the peroxide value showed no differences between the egg yolk control and the emulsions. Therefore, egg yolk was observed to be an efficient encapsulating food matrix that protects n-3 polyunsaturated fatty acids against oxidation and degradation.     

超临界CO2萃取蛋黄粉中甘油三酯和胆固醇的影响因素研究

以蛋黄粉为原料,研究用超临界ＣＯ２萃取技术脱除其中的甘油三酯和胆固醇的操作条件,得到了萃取压力、萃取时间ＣＯ２流量等因素对脱除率的影响。在２４ＭＰａ、５ｈ、５０℃的条件下,某油三酯和胆固醇的脱除率可达８０％以上。     

Profiling and Qualitative Assessment of Enzymatically and Thermally Oxidized Egg Yolk Phospholipids using a Two-Step High-Performance Liquid Chromatography Protocol

A two-step high-performance liquid chromatography (HPLC) method for the profiling and qualitative assessment of oxidized phospholipids (oxPL) present in foods was developed. The applicability of the investigated two-step HPLC protocol was verified for separation of enzymatically and thermally oxidized hen egg yolk phospholipids (PL) as a relevant food model. In the first step, seven individual PL classes were separated using hydrophilic interaction liquid chromatography (HILIC). The collected fractions of two main egg yolk PL classes—phosphatidylethanolamines and phosphatidylcholines—were further directed to the second step of separation aimed at profiling and qualitative assessment of their oxidized species. For this purpose, the reverse phase (RP) chromatography coupled to charged aerosol, ultraviolet detection (UV) and mass spectrometry detection were employed. A database of potential oxPL including primary (hydroperoxides) and long-chain secondary PL oxidation products (epoxides, alcohols, and ketones) as well as some of their possible combinations was created. Additionally, the results were compared with the profiles of PL hydroperoxides obtained using thin layer chromatography (TLC) with N,N-dimethyl-p-phenylenediamine visualization.     

超临界二氧化碳萃取蛋黄油实验研究

介绍超临界二氧化碳萃取技术提取蛋黄油的工作原理及工艺流程.设计了正交实验,考察了萃取压力、萃取温度、萃取时间等参数对萃取率的影响,确定了最佧工艺条件.     

酶法水解和筛选蛋黄蛋白质中的药物前驱型降血压肽

为了筛选鸡蛋蛋黄蛋白质的酶解产物中的药物前驱型降血压肽,将鸡蛋蛋黄蛋白质经超临界CO2-乙醇萃取脱脂和NaOH溶液脱磷处理,用12种蛋白酶在各自适宜的条件下进行酶解,采用HPLC分析各酶解产物对血管紧张素酶(ACE)的抑制活性(IC50),并对IC50较小的6种水解产物进行保温实验,筛选药物前驱型降血压肽。结果显示,12种酶解产物对ACE的IC50值在0.69 mg.mL-1~4.06 mg.mL-1;保温实验显示仅有酶L的酶解产物IC50值明显减小,即由1.19 mg.mL-1降至0.59 mg.mL-1,其他5种酶解产物的IC50值则保持不变或升高,表明酶L的酶解产物中含药物前驱型降血压肽。     

Antioxidant and ACE Inhibitory Bioactive Peptides Purified from Egg Yolk Proteins

Protein by-products from the extraction of lecithin from egg yolk can be converted into value-added products, such as bioactive hydrolysates and peptides that have potential health enhancing antioxidant, and antihypertensive properties. In this study, the antioxidant and angiotensin converting enzyme (ACE) inhibitory activities of peptides isolated and purified from egg yolk protein were investigated. Defatted egg yolk was hydrolyzed using pepsin and pancreatin and sequentially fractionated by ultrafiltration, followed by gel filtration to produce egg yolk gel filtration fractions (EYGF). Of these, two fractions, EYGF-23 and EYGF-33, effectively inhibited the peroxides and thiobarbituric acid reactive substance (TBARS) in an oxidizing linoleic acid model system. The antioxidant mechanism involved superoxide anion and hydroxyl radicals scavenging and ferrous chelation. The presence of hydrophobic amino acids such as tyrosine (Y) and tryptophan (W), in sequences identified by LC-MS as WYGPD (EYGF-23) and KLSDW (EYGF-33), contributed to the antioxidant activity and were not significantly different from the synthetic BHA antioxidant. A third fraction (EYGF-56) was also purified from egg yolk protein by gel filtration and exhibited high ACE inhibitory activity (69%) and IC₅₀ value (3.35 mg/mL). The SDNRNQGY peptide (10 mg/mL) had ACE inhibitory activity, which was not significantly different from that of the positive control captopril (0.5 mg/mL). In addition, YPSPV in (EYGF-33) (10 mg/mL) had higher ACE inhibitory activity compared with captopril. These findings indicated a substantial potential for producing valuable peptides with antioxidant and ACE inhibitory activity from egg yolk.     

超临界二氧化碳萃取蛋黄油的研究

采用超临界萃取方法,以二氧化碳作为溶剂,在比较温和的实验条件下,从蛋黄粉中萃取蛋黄油。实验条件为：温度３５℃～７５℃,压力２５ＭＰａ～３６ＭＰａ,ＣＯ２的流量约７．０ｋｇ／ｈ。实验得到最佳的萃取条件为：５５℃、２８ＭＰａ～３６ＭＰａ。气相色谱分析结果表明：在不同的萃取阶段蛋黄油的组成类似。并且得到了不同实验条件下蛋黄油在超临界二氧化碳中的溶解度     

高效液相色谱-蒸发光散射检测法分析蛋黄磷脂酰胆碱(英文)

Egg yolk phosphatidylcholine(EYPC) is being widely used in food and pharmaceutical industries nowadays owing to its surface activity,pharmaceutical usefulness,and so on.Common determination methods of phospholipids were based on the American Oil Chemists’ Society(AOCS) Official Method Ja7b-91,in which n-hexane/2-propanol/acetate buffer was used as the mobile phase.In order to achieve desired results,gradient elu-tion or buffer solution was used,which made the detection process more complicated.Moreover,water or buffer solution could affect the silica gel column both on its lifespan and the separation efficiency significantly.In this study,different mobile phase and detector were used to simplify EYPC analyzing process instead of using water within the mobile phase.The optimized HPLC operating conditions are as follows:pure methanol as a mobile phase,flow rate of 1.0 ml·min-1,silica gel column(250 mm×4.6 mm,5 μm,Inertsil GLTM),column temperature 30 ℃ and low temperature evaporative light scattering detector(40 ℃,0.35 MPa) as used.Under this optimal condition,the linear relative coefficient of the standard curve is 0.998 and the recovery was in the range of 96.83%-101.58% with a relative standard deviation of 1.79%(n=6).     

乙醇提取鸭蛋黄卵磷脂的工艺研究

采用正交实验和单因素实验方法,考察了提取温度、乙醇浓度、提取时间、料液比对鸭蛋卵磷脂提取率的影响。结果表明：在提取温度30℃、乙醇浓度92%、提取时间60min且料液比为1：5的条件下,从鸭蛋黄中提取卵磷脂的得率达9.92%。     

卵磷脂 (PC)脂质体诱发的乳液凝集举动(英文)

用光散射、荧光漏出法、表面张力、电气泳动等方法研究了添加卵磷脂 (PC)脂质体后的十六烷乳液油滴的凝集举动。调查了 3个可变因子 :①体系中LaCl3 的浓度变化 ;②脂质体的浓度 ;③脂质体的大小。实验结果表明 :在吸附的初级阶段 ,脂质体在油滴表面上将保持它的球状结构 ,之后将缓慢破裂 ,最后在油滴表面上形成单分子膜。所以 ,在脂质体被添加后的最后阶段 ,吸附在油滴表面上的脂质体将通过粒子间的架桥反应诱发油液聚集     

抗流感病毒鸡卵黄免疫球蛋白IgY的制备和性质

用流感病毒免疫产蛋鸡,获得的免疫卵黄经两步盐析和一步凝胶过滤分离得到的IgY经SDS-PAGE分析其纯度在95%以上,纯化的IgY经胃蛋白酶(pH=4 0,37℃)酶解后,得到的片段抗体为Fab。采用竞争抑制ELISA法对IgY和Fab的免疫反应活性进行了对比,表明IgY经胃酶切解后保留了约70%的反应活性。     

鸡卵黄乙肝病毒特异性转移因子的制备及鉴定

目的制备鸡卵黄乙肝病毒特异性转移因子(EYHBV-TF),并检测其免疫活性。方法用乙肝疫苗免疫母鸡,收集鸡蛋,取卵黄进行透析,制备EYHBV-TF,参照药典要求,采用光谱法、高效液相色谱法(HPLC)、Lowry法等检测其理化性质。采用白细胞粘附抑制法(LAI)和迟发型皮肤超敏试验(DTH)检测特异免疫活性。结果EYHBV-TF是一种可透析、含有18种氨基酸、相对分子质量小于12000的小分子物质,其多肽含量为1·2mg/ml,核糖含量为152·94μg/ml,pH6·9±0·5,蛋白反应阴性,最大紫外吸收光谱在270nm处。该EYHBV-TF能明显抑制小鼠白细胞粘附(P<0·01),并能诱导小鼠跖趾部皮肤的迟发型超敏反应(P<0·01),与猪脾淋巴细胞制取的乙肝特异性转移因子(PSHBV-TF)检测结果接近(P>0·05)。而正常卵黄提取液组、非特异性转移因子和甲肝抗原(HAAg)对照组均不能表现出这两种效应(P>0·05)。结论EYHBV-TF与PS-TF主要理化性质和作用相类似,均具有乙肝抗原特异性细胞免疫活性。     

Physicochemical Characterization of Whole Egg Powder Microencapsulated by Spray Drying

Physical characterization and oxidative stability of egg powder microencapsulated by spray drying were studied in this work. The wall material (gelatin, lactose, pullulan, and their mixtures) and liquid egg mixtures were prepared by homogenization at 22,000 rpm for 60 s. The spray drying was carried out at pilot-scale spray dryer (Niro Mobile Minor, Søborg, Denmark). The spray-dried egg powders were analyzed for moisture content, water activity, peroxide value, total cholesterol oxidation products (TCOPs), particle properties, and bulk properties. Using gelatin as wall material resulted in a significant increase in the moisture content and water activity of egg powder during storage and it improved flowability. Egg powders containing pullulan as wall material showed a fibrous structure and had the lowest bulk density. Adding lactose as wall material increased the oxidative stability, which was indicated with lowest peroxide value and TCOPs level of egg powder.     

The Fractional Extraction of Lipids and Cholesterol from Dried Egg Yolk Using Supercritical Carbon Dioxide

Results from extraction of cholesterol and other lipid components from dried egg yolk using supercritical carbon dioxide at the range of temperature from 40°C to 60°C and pressure between 150 bar und 350 bar for 2.5 hours and 2.7 kg CO₂ consumption is described in this paper. The solubility of lipids and cholesterol increased with the increase of pressure at a constant temperature of 50°C, while at a constant pressure, more cholesterol was removed at 45°C than that at other temperatures. Nearly 60 percent cholesterol was removed at 45°C and 250 bar. Lipids were more efficiently extracted at 60°C than at 40°C at 250 and 350 bar, however, a decrease in the total extracted lipids was observed with the increase in temperature at 150 bar. The removed total lipids from dried egg yolk at 250 bar/55°C was over 80 %.     

Foam-Mat Freeze Drying of Egg White—Mathematical Modeling Part II: Freeze Drying and Modeling

Foam-mat freeze drying is one of the promising methods of drying, which utilizes advantages of both freeze drying and foam-mat drying. Egg white with its excellent foaming properties makes a suitable candidate for foam-mat freeze drying. Experiments were conducted to study foam-mat freeze drying of egg white, in an effort to determine the suitability of this method. Xanthan gum (XG) at 0.125% concentration was used as stabilizer for foaming. The results showed that the addition of xanthan gum during foaming has a positive impact in reducing the total drying time and also produces excellent quality egg white powder. The addition of stabilizer also plays an important role in improving drying. Simple models were applied for determining drying time and diffusion coefficients during freeze drying.     

Dietary High‐Oleic Acid Soybean Oil Dose Dependently Attenuates Egg Yolk Content of n‐3 Polyunsaturated Fatty Acids in Laying Hens Fed Supplemental Flaxseed Oil

Chickens can hepatically synthesize eicosapentaenoic acid (20:5 n‐3) and docosahexaenoic acid (22:6 n‐3) from α‐linolenic acid (ALA; 18:3 n‐3); however, the process is inefficient and competitively inhibited by dietary linoleic acid (LNA; 18:2 n‐6). In the present study, the influence of dietary high‐oleic acid (OLA; 18:1 n‐9) soybean oil (HOSO) on egg and tissue deposition of ALA and n‐3 polyunsaturated fatty acids (PUFA) synthesized from dietary ALA was investigated in laying hens fed a reduced‐LNA base diet supplemented with high‐ALA flaxseed oil (FLAX). We hypothesized that reducing the dietary level of LNA would promote greater hepatic conversion of ALA to very long‐chain (VLC; >20C) n‐3 PUFA, while supplemental dietary HOSO would simultaneously further enrich eggs with OLA without influencing egg n‐3 PUFA contents. Nine 51‐week‐old hens each were fed 0, 10, 20, or 40 g HOSO/kg diet for 12 weeks. Within each group, supplemental dietary FLAX was increased every 3 weeks from 0 to 10 to 20 to 40 g/kg diet. Compared to controls, dietary FLAX maximally enriched the total n‐3 and VLC n‐3 PUFA contents in egg yolk by 9.4‐fold and 2.2‐fold, respectively, while feeding hens 40 g HOSO/kg diet maximally attenuated the yolk deposition of ALA, VLC n‐3 PUFA, and total n‐3 PUFA by 37, 15, and 32%, respectively. These results suggest that dietary OLA is not neutral with regard to the overall process by which dietary ALA is absorbed, metabolized, and deposited into egg yolk, either intact or in the form of longer‐chain/more unsaturated n‐3 PUFA derivatives.