油脂体稳定性影响因素及机理的研究进展

油脂体是植物储藏脂质的重要细胞器。近年来,随着对于油脂体研究的不断深入,人们发现由于油脂体具有天然的蛋白-磷脂界面层,使得油脂体能够分散在水相中形成水包油（O/W）乳化体系且具有很好的理化稳定性。人们开始尝试将油脂体应用于食品、饲料及个人护理产品等领域中。探究油脂体稳定性的影响因素及机理对油脂体的实际生产应用具有现实意义。油脂体结构的完整性及油脂体膜表面镶嵌的蛋白质是维持油脂体稳定性的决定因素。油脂体乳液的稳定性与油脂体的组成、提取方法、外源性蛋白质、温度、pH和盐浓度等条件有关。本文论述了油脂体的结构与组成、乳液稳定性和应用,为油脂体的研究及应用提供参考。     

大豆种子萌发后油脂体乳液稳定性的研究

以大豆为原料,大豆种子经萌发处理后的油脂体乳液为研究对象,通过测量乳化稳定性、过氧化值、硫代巴比妥酸值（TBARS值）及酸价等指标,比较了大豆种子不同萌发时间油脂体乳液的稳定性,研究了不同处理条件（NaCl浓度、pH、贮藏温度）对大豆种子萌发后油脂体乳液稳定性的影响。实验结果表明,大豆种子萌发后油脂体提取率逐渐降低,20 h（12.36%±0.21%）至27 h（10.89%±0.28%）油脂体提取率呈逐渐下降趋势,且27 h后提取率下降显著（P<0.05）。室温下贮藏14 d样品出现不同程度的絮凝。不同萌发时间油脂体乳液稳定性也不同,27 h表面疏水性（99.78±0.88）最大,且乳化稳定性（23.49±0.39）最好。经不同NaCl浓度、pH、贮藏温度处理后,随NaCl浓度的增加,萌发后的大豆油脂体乳液乳化活性无显著变化（P>0.05）,乳化稳定性在NaCl浓度为0~150 mmol/L时呈下降趋势,大于150 mmol/L时无显著变化,150与200 mmol/L时分别为（4.75±0.12）和（4.74±0.14）min,但过氧化值在贮藏0~6 d时显著增加（P<0.05）;pH越高,萌发大豆油脂体乳液的ζ-电势及乳化活性越小,pH为4时乳化活性为（19.13±0.23）m2/g,过氧化值和TBARS值变化显著（P<0.05）;贮藏温度上升,萌发大豆油脂体乳液过氧化值升高,酸价无显著性变化（P>0.05）。不同萌发时间大豆种子油脂体乳液稳定性均存在差异,且萌发27 h后的大豆油脂体较其他萌发时间更稳定。NaCl浓度和pH都对萌发大豆油脂体乳液稳定性有较大影响,且贮藏温度对其影响相对较小。可为今后萌发大豆油脂体的应用提供理论基础。     

巴氏灭菌对不同油脂体乳液氧化稳定性的影响

为探究巴氏灭菌对大豆、葵花、花生、芝麻和核桃油脂体乳液氧化稳定性的影响,本研究测定不同油脂体的基本组成、相关蛋白组成、脂肪酸组成和相对含量,然后利用动态光散射、激光共聚焦显微镜等研究巴氏灭菌（85 ℃加热10 min）对油脂体乳液物理稳定性和氧化稳定性的影响。结果表明：不同油脂体的基本组成、相关蛋白组成和脂肪酸组成存在明显差异,油脂体相关蛋白由内源膜蛋白和外源蛋白组成,油脂体脂肪酸以不饱和脂肪酸为主,其中油酸、亚油酸和α-亚麻酸是主要的不饱和脂肪酸。5 种不同原料油脂体中,大豆油脂体蛋白质量分数和水分质量分数最高,而油脂质量分数最低;花生油脂体总饱和脂肪酸相对含量（21.27%）最高,核桃油脂体总不饱和脂肪酸相对含量（90.10%）最高。巴氏灭菌可显著改善大豆和花生油脂体乳液氧化稳定性,而对葵花、芝麻和核桃油脂体乳液起促进氧化作用。本研究可为油脂体在沙拉酱、植物奶等产品应用提供参考。     

不同油脂体结构及性质的差异

以大豆、花生和葵花籽源油脂体为研究对象,分析比较油脂体结构、组成、蛋白质分子质量大小、Zeta电位、粒径分布和乳化性质差异,并对油脂体蛋白质进行圆二色性光谱分析。结果表明,不同源油脂体具有相似的组成和结构;大豆油脂体中蛋白质与脂肪比例（0.086∶1）显著高于花生油脂体（0.018∶1）和葵花籽油脂体（0.028∶1）（P＜0.05）,而大豆油脂体的平均粒径（（0.93±0.07）μm）却显著低于花生油脂体（（2.58±0.06）μm）和葵花籽油脂体（（1.64±0.03）μm）（P＜0.05）;大豆油脂体疏水氨基酸总量最高,而花生油脂体疏水氨基酸总量最低;大豆油脂体Zeta电位、乳化活性和乳化稳定性均显著高于花生油脂体和葵花籽油脂体（P＜0.05）;大豆油脂体蛋白质的α-螺旋结构含量（（43.58±0.12）%）显著高于花生油脂体（（35.43±0.06）%）和葵花籽油脂体蛋白质（（37.00±0.09）%）（P＜0.05）;而花生油脂体蛋白质的β-折叠和无规则卷曲含量最高。不同源油脂体虽然具有相似的组成和结构,但性质存在差异,这为未来油脂体更好地应用于食品工业生产提供理论支持。     

Physical and oxidative stability of pre-emulsified oil bodies extracted from soybeans

Soybeans contain oil bodies that are coated by a layer of oleosin proteins. In nature, this protein coating protects the oil bodies from environmental stresses and might be utilised by food manufacturers for the same purpose. In this study, an aqueous extraction method was developed to increase the yield of oil bodies extracted from soybean. This method involved a two-step procedure: (i) blending, dispersion, and filtration of soybeans; (ii) homogenisation, suspension, and centrifugation of the filter cake. Using this extraction method about 65% of the oil bodies could be obtained. The mean particle diameter (d₄₃) and sedimentation of the resulting oil bodies increased during storage, suggesting they were prone to aggregation. Heat treatment (90 °C, 30 min) of the oil body suspensions immediately after extraction improved their storage stability, which was attributed to deactivation of endogenous enzymes such as lipase and lipoxygenase. Heat treatment did not adversely affect the oxidative stability of the oil body suspensions at pH 3 or 7 during storage at 37 °C. These results suggest that this aqueous extraction method can be used to prepare oil body suspensions with improved long-term stability.     

Extraction Technology Can Impose Influences on Peanut Oil Functional Quality: A Study to Investigate the Lipid Metabolism by Sprague–Dawley Rat Model

In this study, peanut oil was prepared by cold pressing (temperature under 60 °C), hot pressing (temperature above 105 °C), and enzyme‐assisted aqueous extraction technology. Influences of an extraction technology on the oil fatty acid composition and the content of minor bioactive compounds, including tocopherols, polyphenols, and squalene, were investigated in detail. High‐fat‐diet Sprague–Dawley (SD) rat model was then established to probe the impact of cold‐pressed peanut oil (CPO), hot‐pressed peanut oil (HPO), and enzyme‐assisted aqueous‐extracted peanut oil (EAO) on lipid metabolism outcomes, to explore influences of different extraction technologies on lipid functional quality. Results showed that oleic acid was the predominate fatty acid in the EAO (52.57 ± 0.11%), which was also significantly higher (P < 0.05) than CPO and HPO. The HPO showed higher total tocopherol and polyphenol contents (206.84 ± 6.93 mg/kg and 47.87 ± 6.50 mg GA/kg, respectively) than CPO and EAO (P < 0.05). However, the squalene content in CPO was 475.47 ± 12.75 mg/kg, which was the highest among the three oils (P < 0.05). The animal experiment results revealed that EAO could be more prone to induce lipid accumulation in the liver, which may likely to cause nonalcoholic fatty liver disease. However, the serum lipid profiles indicated that the CPO was more beneficial than the EAO and HPO in lowering the serum low‐density lipoprotein cholesterol, alanine aminotransferase, and aspartate aminotransferase contents, and increasing the high‐density lipoprotein cholesterol content. All of our efforts indicated that an extraction technology can affect the peanut oil lipid fatty acid composition, the bioactive compounds content, and, correspondingly, the lipid metabolism in SD rats.     

植物种子油体的研究与应用进展

油体是由半单位膜包裹液态三酰甘油酯而成的球体,作为一种天然乳液具有良好的稳定性。综述了植物种子油体的结构与组成、油体相关蛋白的种类和特征,重点介绍了国内外与油体应用相匹配的提取和纯化技术的研究进展,并对油体性质以及不同领域的潜在应用,尤其是食品领域中的应用研究做了阐述。     

Combination of Alcalase 2.4 L and CaCl2 for aqueous extraction of peanut oil

The combined application of CaCl₂ and Alcalase 2.4 L to the aqueous extraction process of peanuts was evaluated as a method to destabilize the oil body (OB) emulsion and improve the oil yield. After adding 5 mM CaCl₂, the oil yield was reached to 92.0% which was similar with that obtained using Alcalase 2.4 L alone, and the required enzyme loading was decreased by approximately 60 times. In addition, the demulsification mechanism during aqueous extraction process was also investigated. Particle size and zeta-potential measurements indicated that the stability of the peanut OB emulsion dramatically decreased when CaCl₂ was added. Under these conditions, the demulsification of Alcalase 2.4 L performed was more efficiently. SDS–PAGE results showed that adding CaCl₂ changed the subunit structure of the peanut OB interface proteins and promoted the cross-linking among the arachin Ara h3 isoforms, resulting in unstable emulsions.     

The effect of preultrasonic process on oil content and fatty acid composition of hazelnut,peanut and black cumin seeds

In this study, the effect of different sonication times (10, 20, and 30 min) on oil yields, extracted by using soxhlet together with preultrasonic treatment, and fatty acid composition of seed/kernels were investigated. The sonication of samples for 30 min caused the highest increase in oil yield of hazelnut (from 62.38 to 63.60%) and black cumin (from 27.90 to 31.80%) (p < .05). The appropriate sonication time for oil yield of peanut was 10 min, with the range of 51.50%. After sonication process, the dominant fatty acid contents of all samples showed a change and the major decrease in oleic acid amount of hazelnut (from 75.20 to 74.27%) and peanut oils (from 57.10 to 56.69%) and linoleic acid content of black cumin (from 58.38 to 57.50%) were determined when samples sonicated for 30 min (p < .05). Sonication process caused a decreasing in black cumin oil, and the reduction increased with sonication time.

Practical applications

Ultrasound‐assisted extraction method can be used as an alternative extraction method for conventional extraction. Ultrasonic‐assisted extraction has some advantages as being efficiency, speed and using low temperatures, which prevents thermal damage. The ultrasound process enables to greater influence of solvent into the sample matrix and increases mass transfer. Thereby, the higher extract yield, almost 23%, provided with ultrasonic‐assisted extraction in comparison to soxhlet extraction.     

高压均质影响葵花籽油体乳液理化性质的研究

研究pH 3.5～8.0条件提取的葵花籽油体基本性质,探究利用高压均质压力(40、60、80、100 MPa)对不同葵花籽油体乳液(10%)的蛋白质组成及粒径、流变学特性、储藏稳定性的影响。结果表明：随着提取pH的升高,葵花籽油体的蛋白质质量分数由14.19%降为2.97%,油体结合的外源性蛋白减少;脂肪质量分数由47.98%增加到68.01%;油体等电点由4.0增加至4.9。随着均质压力的升高,所有油体蛋白质结构无明显改变;油体乳液粒径呈现先降低后升高的趋势,油体乳液黏度有所降低,并提高了储藏稳定性,其中,pH 5.0提取的油体经60 MPa均质后乳液粒径最小(229 nm),稠度指数(k值)较低,储藏稳定性最佳。     

外源蛋白对大豆油脂体稳定性的影响

通过水提法辅助去离子水洗涤或碱液洗涤,从大豆中分别提取得到富含外源蛋白的粗油脂体（crude oil bodies,COB）和几乎不含外源蛋白的纯油脂体（purified oil bodies,POB）,考察不同环境因素（pH值、Na＋浓度和热处理温度）对COB和POB稳定性的影响,以及油脂体的流变学特性。结果表明：大豆POB中蛋白主要成分为油体蛋白,而COB中除油体蛋白外还含有大量外源蛋白,主要包括大豆球蛋白和β-伴大豆球蛋白。相比于POB（平均粒径（475.06±4.49）nm和Zeta电位（－14.00±1.86）mV）,外源蛋白的存在导致COB具有较高的平均粒径（（552.93±9.40）nm）和较低的Zeta电位（（－35.03±0.60）mV）。大豆COB中蛋白等电点在pH 4.5左右,此pH值也接近大豆球蛋白和β-伴大豆球蛋白等电点,而大豆POB中蛋白等电点位于pH 5.5左右。在不同pH值和Na＋浓度下,大豆POB较COB具有更好的稳定性,这可能是由于大豆COB中外源蛋白的存在使其更易受环境影响而产生静电和疏水作用的改变,从而降低其稳定性,而不同热处理温度对大豆COB和POB稳定性影响不大。此外,大豆COB和POB均具有剪切稀化特性,但COB的黏度高于POB,这进一步证明了外源蛋白的存在对大豆油脂体加工性能的影响,为不同油脂体的产品研发提供思路。     

Chemical and structural characterisation of almond oil bodies and bovine milk fat globules

Lipids in almonds are present as oil bodies in the nut. These oil bodies are surrounded by a membrane of proteins and phospholipids and are a delivery vehicle of energy in the form of triglycerides, similarly to the more studied bovine milk fat globule membrane. Chemical, physical and microscopic analyses revealed major differences in the composition and structure of almond oil bodies and bovine milk fat globules. The lipids of both natural emulsions differed in degree of unsaturation, chain length, and class. The almond oil body membrane does not contain any cholesterol or sphingomyelin unlike the bovine milk fat globule membrane. Therefore, the phospholipid distribution at the surface of the oil bodies did not present any liquid-ordered domains. The membranes, a monolayer around almond oil bodies and a trilayer around bovine fat globules, may affect the stability of the lipid droplets in a food matrix and the way the lipids are digested.     

Removing peanut allergens by tannic acid

Tannic acid (TA) forms insoluble complexes with proteins. The aims here were to remove major peanut allergens as insoluble TA complexes and determine if they would dissociate and release the allergens at pH 2 and 8 (gut pH). Release of the allergens in the gut could lead to absorption and consequently an allergic reaction. TA (0.25, 0.5, 1, and 2 mg/ml) was added to a peanut butter extract (5 mg/ml; pH 7.2), stirred, and centrifuged. The precipitates were then suspended in buffer at pH 2, centrifuged, re-suspended at pH 8, and centrifuged. Supernatants from each step were analysed by SDS–PAGE, ELISA, and Western blots. The effect of NaCl (1 M) on complexes was also determined. Results showed that complexes formed at a TA concentration >0.5 mg/ml did not release major peanut allergens at pH 2 and 8, regardless of 1 M NaCl being present or not. IgE binding of the extracts was reduced substantially, especially at a TA concentration of 1–2 mg/ml. Animal or clinical studies are still needed before TA can find an application in the development of low-allergen peanut products/beverages or the removal of peanut allergens due to accidental ingestion.     

植物油体的提取及其乳化体系研究进展

油体是植物组织中贮存油脂的特殊细胞器,三酰甘油构成了油体的疏水性内核,磷脂分子和油质蛋白构成油体外层的单层膜结构,赋予油体良好的稳定性,能够抵抗干旱、高温等外界不利条件,并能保持油体在体外水溶液中的稳定,具有广阔的开发前景。本文对植物油体的组成和结构、植物油体的提取及油体乳液乳化体系（如油体乳液乳化体系组成、乳化体系的稳定性及其乳化机理）等的研究进展进行综述,以期为水（酶）法提取植物油过程中乳液的有效破乳和植物油体产品的开发、应用提供参考。     

盐析辅助水蒸气蒸馏法提取甘松精油及其挥发性香气成分分析

为提高甘松精油提取效率,该试验以精油得率为评价指标,通过单因素试验及正交试验优化了盐析辅助水蒸气蒸馏法提取条件,并采用气相色谱-质谱联用法（GC-MS）分析甘松精油的香气成分。结果表明,盐析辅助水蒸气蒸馏法提取甘松精油最佳条件为NaCl含量3%、料液比1∶5(g∶mL)、浸泡时间5 h、蒸馏时间4 h。此优化条件下甘松精油得率为3.72%。GC-MS结果表明,共检测出56种挥发性香气物质,其主要成分多为萜类化合物,且以倍半萜数种类最多。该研究优化了盐析辅助水蒸气蒸馏提取甘松精油的工艺,可为甘松精油的进一步开发利用提供理论依据。     

Novel oil extraction technologies: Process conditions,quality parameters,and optimization

Conventional techniques of extracting oil using organic solvents pose health, safety, and environmental concerns. In modern extraction methods, green solvents such as water, ethanol, ethyl acetate, carbon dioxide, ionic liquids, and terpenes are currently gaining prominence. These green solvents present no signs of pollution and remain in liquid form over a temperature range of 0 to 140 °C. Other techniques covered in this review include microwave‐assisted enzymatic extraction, ultrasound‐assisted extraction, supercritical fluid technology, high pressure–assisted extraction, and pulse electric field–assisted extraction. These techniques are considered environmentally friendly because they exhibit less hazardous chemical synthesis, use renewable feedstock, and reduce the chemical load and emissions generated by organic solvents. Aqueous enzymatic extraction is a novel technique that uses enzymes as the medium for extraction of oil. Selection of the enzymes solely depends on the structure of the oilseed and the composition of the cell wall. Studies reveal an enzyme to substrate ratio of 1% to 8%, the temperature of 40 to 55 °C, and a pH of 4 to 8 to be typical for enzymatic extraction of oil from different oilseeds. Microwave‐assisted extraction has proven to impart significant effects on mass transfer and offers high throughput and extraction efficiency. A microwave power of 275 to 1,000 W and a temperature range of 30 to 60 °C are noticed in the different studies. The review presents a comprehensive account of the modern extraction techniques, the parameters responsible for yield and quality, and their industrial applications. Besides, the review highlights the optimized parameters for oil extraction from different oil‐bearing materials.     

Effect of pasteurization on membrane proteins and oxidative stability of oil bodies in various crops

Oil bodies (OBs) are natural pre-emulsion systems and an ideal green food additive. However, their proclivity to oxidation limits the applications of OBs. In this study, the effect of pasteurization (85 and 125 °C; 1 min) on membrane proteins and the oxidative stability of various OBs (soybean, sunflower, peanut, sesame, and walnut) were investigated. The membrane proteins are extracted from the OBs. The ultrahigh-temperature pasteurization (125 °C, 1 min) eliminated lipoxygenase of soybean and peanut OBs. Furthermore, oleosin exhibited a higher denaturation temperature (approximately 100 °C) than extrinsic proteins (approximately 50 °C). Pasteurization induced the conversion of the α-helix structure to a disordered structure by rearranging the hydrogen bonds. The pasteurized soybean and peanut OBs exhibited a high oxidative stability owing to their stable membrane structures and decreased lipoxygenase activity, while sunflower, sesame, and walnut OBs did not exhibit good oxidative stability because of their vulnerable membranes, a large number of unsaturated fatty acids, and severe aggregation of droplets. Simulated milk based on pasteurized soybean and peanut OBs (125 °C, 1 min) maintained outstanding storage stability. These results confirmed that pasteurized soybean and peanut OBs have the potential as a skim milk additive for the benefit of the consumer.     

花生水酶法蛋白质提取及制油研究

以纤维素酶为主体包含果胶酶的复合酶系处理花生水剂法制油过程中碾磨后的油料,能显著提高花生油收率及花生蛋白得率。经优化实验得出酶处理的最适参数为：加酶量０．３％,酶反应时间４ｈ、ｐＨ６．４、温度４９℃。     

Stabilization of soybean oil body emulsions using κ, ι, λ-carrageenan at different pH values

Oil bodies, with their unique structural proteins, oleosins, are known to be useful in foods and other emulsion systems. The influence of ??, ??, and ??-carrageenans on the stability of soybean oil body emulsions at different pH values (pH 3, 4, 5 and 7) was investigated by particle electrical charge, particle size distribution, creaming stability and confocal laser scanning microscopy measurements. In acidic environment (pH 3, 4 and 5), the droplet charge of soybean oil body emulsions stabilized with carrageenan decreased with increasing carrageenan concentration for all types of carrageenan investigated, suggesting their adsorption to the oil body droplet surfaces. Extensive droplet aggregation and creaming were observed in the emulsions stabilized with ??-carrageenan at pH 3 and 5, indicating that soybean oil body droplets were bridged by carrageenan. At pH 7, there was no significant change in the droplet charge of soybean oil body emulsions stabilized with three types of carrageenan, but the emulsions stabilized with ??-carrageenan were more stable to creaming due to depletion flocculation than the emulsions stabilized with ?? or ??-carrageenan after seven days storage. The probable reason was that ??-carrageenan, which had the most densely charged helical structure, was most effective at creating highly charged interfacial membranes, thus reducing the depletion flocculation to occur.     

低温花生粕蛋白制备及其饮料稳定性分析

以低温花生粕为原料,利用碱溶酸沉法提取花生分离蛋白,继而制备花生蛋白饮料,考察自制花生蛋白饮料的稳定性,并研究其氮溶指数、乳化活性及乳化稳定性等功能特性。结果表明,最佳工艺条件为pH 9.5、碱提温度55℃、料液比1∶11(g/mL)、提取时间2.5 h,此条件下花生分离蛋白提取率可达90.25%。十二烷基硫酸钠-聚丙烯酰胺凝胶电泳分析显示,其中包含花生蛋白所有特征条带。花生蛋白饮料的平均粒径(D[4,3])为4.31μm,稳定性分析仪测出粒子动态变化斜率(Slope)值为26.66%/h。低温花生粕制备的花生蛋白饮料具有良好的稳定性,这为花生粕高值化利用提供了新方向。