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。     

复合界面对食品乳液中脂肪消化的影响

以中链甘油三酯为油相制备乳液,将天然高分子与小分子表面活性剂复配,构建阿拉伯胶（gum arabic,GA）或乳清分离蛋白（whey protein isolate,WPI）与吐温80（T80）的复合乳液界面。采用逐层添加或混合添加的方式,调控界面组分的吸附次序,构建不同界面结构的乳液体系。采用体外模拟小肠消化模型和界面流变技术等手段剖析乳液界面结构对脂肪消化速率的影响。结果表明：对于GA、WPI和T80形成的单一乳液体系,GA和WPI的界面弹性模量高于T80界面,黏弹性好。三者抗胆盐取代和延缓脂肪消化能力依次为GA＜WPI＜T80。在大分子GA或WPI与小分子T80形成的复合乳液体系中,由T80吸附占主导的界面,其延缓脂肪消化和界面抗胆盐取代的能力优于GA或WPI与T80共同吸附的界面结构。     

高碱性提取的大豆油体的成分变化研究

以大豆油体(OB)为研究对象,详细地考察了高碱性提取条件对大豆油体成分的影响,主要包括油体主要成分(中性脂、蛋白质和磷脂)的含量、油体表面的蛋白质种类和氨基酸组成、中性脂脂肪酸组成和生育酚组成。结果表明,高碱性提取会使大豆油体表面的蛋白质和磷脂部分脱离油体,蛋白质/中性脂比值由0.097(pH 6.8 OB)减小为0.058(pH 11 OB),磷脂/中性脂比值由0.068(pH 6.8 OB)减小为0.029(pH 11OB);对中性脂部分(生育酚、脂肪酸)基本无影响;高碱性提取影响油体粒径和zeta电位,粒径由(509±3)nm(pH 6.8 OB)减小为(451±7)nm(pH 11 OB),等电点由介于4.5~5(pH 6.8 OB)提高为5.5~6(pH 11 OB);同时说明,油体特殊的天然乳化结构对于保护植物种子中的中性脂意义重大。     

蛋白界面膜及其评价方法研究进展

食品中乳化类产品的稳定性决定了其价值和顾客满意度,天然蛋白的乳化特性多年来受到食品胶体和界面科学领域广泛关注。蛋白吸附到水油界面形成的黏弹性薄膜具有降低界面张力、维持乳液稳定的特性。研究蛋白界面膜的物化性质有助于了解蛋白大分子在水油界面的吸附规律,能够用于评价、表征和预测蛋白乳液稳定性,并为优化蛋白乳液稳定性提供理论基础。基于此,该文对水包油乳液蛋白界面膜结构和影响因素进行探讨,系统综述了目前用于评价蛋白质界面特性的手段和方法,包括微观成像技术、热力学技术、光谱技术和界面流变学技术等,以研究蛋白类乳化液性能在宏观和微观层面的联系,为蛋白质界面膜在乳化食品中的应用提供参考。     

皮革专利

本发明提供了一种天然磷脂复合加脂剂及其制备方法。本发明的天然磷脂复合加脂剂由天然磷脂、亚硫酸化牛蹄油、脂肪醇磷酸酯组成。本发明的天然磷脂复合加脂剂加脂可以提高皮革的皮革的防水性能和丰满度,获得满意的加脂效果,而且该天然磷脂复合加脂剂色泽浅,适宜于浅色革加脂。     

皮革专利

本发明提供了一种天然磷脂复合加脂剂及其制备方法。本发明的天然磷脂复合加脂剂由天然磷脂、亚硫酸化牛蹄油、脂肪醇磷酸酯组成。本发明的天然磷脂复合加脂剂加脂可以提高皮革的皮革的防水性能和丰满度，获得满意的加脂效果，而且该天然磷脂复合加脂剂色泽浅，适宜于浅色革加脂。     

大豆和油菜籽油体形成的天然乳液的稳定性及胃肠道消化特性

为了解大豆和油菜籽油体所形成的天然乳液的稳定性及其在胃肠道中的消化特性,本研究分析了从大豆和油菜籽中所提取植物油体的基本组成;利用激光粒度分析仪、旋转流变仪和激光共聚焦扫描显微镜对大豆和油菜籽油体形成的天然乳液进行了粒径分析、黏度分析和微观结构观察;此外,考察两种油体天然乳液在环境应力（pH值、离子浓度和热处理）条件下的稳定性和在胃肠道消化过程中蛋白和粒径的变化。结果表明：大豆油体蛋白质量分数显著高于油菜籽油体（P＜0.05）,而大豆油体脂质质量分数显著低于油菜籽油体（P＜0.05）。两种油体所形成天然乳液的粒径都随着油体质量分数的增加而减小,其中大豆油体所形成天然乳液的粒径明显低于油菜籽油体所形成天然乳液。通过激光共聚焦扫描显微镜观察到的两种油体微观结构也表明大豆油体所形成的天然乳液粒径小于油菜籽油体所形成的天然乳液,其中大豆油体天然乳液液滴界面覆盖了大量的油体蛋白。大豆油体乳液的黏度高于油菜籽油体乳液。大豆油体乳液在pH 4.0和NaCl浓度分别为100、200 mmol/L时粒径较大,表现不稳定,而油菜籽油体乳液受NaCl浓度的影响较小。大豆油体乳液在85 ℃处理前15 min比较稳定,而油菜籽油体乳液对温度比较敏感。大豆油体乳液在180 min胃消化过程中,乳液的蛋白在前30 min分解较快,然后逐渐趋于平缓,而油菜籽油体乳液在整个胃消化过程中蛋白逐渐被分解。两种油体乳液经胃消化180 min后粒径都明显大于起始乳液粒径,而大豆油体乳液经小肠消化180 min后,其粒径较胃消化过程中明显减小,而油菜籽油体乳液粒径变化不明显。     

油脂体组成、结构及油脂体蛋白研究进展

油脂体是由中性脂质、环绕中性脂质的磷脂和嵌插在磷脂层中的蛋白组成的小球体,是植物油脂储存的重要器官。油脂体中的蛋白对油脂体的独立性、完整性起重要作用,并且在种子萌发过程中,能激活油脂体表面的相关酶类,从而促进代谢,为机体提供能量,促进植物的生长。本文综述油脂体的组成、结构以及油脂体蛋白的结构、功能性质,为油脂体的利用和开发提供参考。     

蛋白质-多糖在乳液油-水界面相互作用研究进展

蛋白质和多糖是具有一定乳化性能的天然生物聚合物,两者可以在乳液油-水界面相互作用并形成具有弹性的界面膜。与化学合成的乳化剂相比,这种天然乳化剂安全性更高,在医药、化妆品和食品等领域更具应用前景,但其乳化特性无法从乳液的宏观状态观察得出,通过分析乳液油-水界面的特性则能够从机理上对乳化剂的乳化效果进行说明。主要介绍了乳液稳定的机理以及探究乳液界面性质的方法,阐述了蛋白质和多糖的复合方式及两者之间的相互作用,并对蛋白质-多糖复合物的研究趋势作出展望。     

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。     

Oil Bodies Extracted from High‐Fat and Low‐Fat Soybeans: Stability and Composition During Storage

Soybeans contain oil bodies (OBs) that encapsulate triacylglycerols (TAGs) with a phospholipid monolayer carrying scattered proteins. In nature, soybean OBs can form natural emulsions in aqueous media and may serve as natural, minimally processed, stable, and pre‐emulsified oil for addition into appropriate food systems. In this study, OBs were obtained by aqueous extraction from the mature seeds of 2 soybean crop cultivars, high‐fat soybean and low‐fat soybeans. The compositions of the extracted OBs were analyzed during storage at room temperature up to 14 d (pH = 7). The oxidative stability of these OBs, stored at 60 °C, was evaluated by measuring the presence of primary (lipid hydroperoxides) and secondary lipid oxidation products (malondialdehyde) by determining the standard peroxide value (PV) and thiobarbituric acid‐reactive substances (TBARS) value. During storage, the contents of unsaturated fatty acids, phospholipids, and tocopherols declined in both OBs, while their mean particle diameters (d₃₂) and ζ‐potentials increased. The changes in PV and TBARS values exhibited a similar trend for both OBs, but the OBs from low‐fat soybeans had significantly lower PV and higher TBARS values than the OBs from high‐fat soybean cultivars (P < 0.05). Overall, the OBs from both soybean cultivars had good stability during storage.     

Inhibition of phenolics on the in vitro digestion of noodles from the view of phenolics release

The inhibition mechanism of buckwheat phenolics on in vitro starch digestion was investigated using extruded noodles with buckwheat starch and phenolic extract (0.50%–2.00%). The cooking quality and reducing sugar released during in vitro digestion were studied, and the extractable phenolic content along digestion was also monitored to reveal a dose–effect relationship between reducing sugar released and the release of phenolics. Noodles containing increased phenolics released less reducing sugar (230–188 mg g⁻¹) during digestion. Cooking and digestion made phenolics more extractable, and most of the phenolics were released at the end of the gastric phase (85.6%–94.8%) compared with during the small intestinal digestion. The IC₅₀ of buckwheat phenolic extract (0.102 mg mL⁻¹) was four times that of acarbose (0.032 mg mL⁻¹). The inhibitory mechanism was further analysed using molecular docking, in which the activity of α-amylase was inhibited by phenolics that bind with active sites of α-amylase through hydrogen bonds and hydrophobic interaction. Phenolics interacting with starch and the released phenolics can both explain the reduction in starch digestion.     

Carboxy Cellulose as Cathode Interfacial Layer for Efficient Organic Solar Cells

Green, biodegradable, and eco-friendly interface materials based on cellulose and its derivatives were prepared for organic solar cells (OSCs). In this work, calcium and two derivatives of cellulose with different carboxy acid groups, denoted as Cellulose-COOH and Cellulose-(COOH)_n, were used as cathode interfacial layers of OSCs, and a blend of the low-band-gap semiconducting polymers thieno[3,4-b]thiophene/benzodithiophene (PTB7) and [6,6]-phenyl C₇₁-butyric acid methyl ester (PC₇₁BM) was chosen as the photoactive layer. OSCs were fabricated with a configuration of indium-doped tin oxide (ITO) /poly(3,4-ethylenedioxythiophene) : polystyrene sulfonate (PEDOT:PSS) /PTB7:PC₇₁BM/Ca or Cellulose-COOH or Cellulose-(COOH)_n/Al. As a result, the effect of cellulose-COOH was the best one among them, and the power conversion efficiency (PCE) reached 8.21% for the devices with cathode interfacial layer of Cellulose-COOH, which was better than that of OSCs using calcium as a modifier (PCE=7.95%). The favorable performance is attributed to the reduced work function and improved electron transfer caused by the introduction of carboxy cellulose between the active layer and the electrode. The developed technology shows great potential in accelerating the diversified applications of cellulose and producing cost-effective and eco-friendly interfaces for OSCs.     

Valorisation of sweet corn (Zea mays) cob by extraction of valuable compounds

The main objective of this study was to investigate the proximate, mineral and phytochemical compositions of sweet corn cob (SCC), often neglected and regarded as agricultural waste. Compositional analysis showed that more than 60% of SCC was composed of insoluble dietary fibre, with cellulose being the major constituent. Results also showed that SCC can be a good source of non-essential protein and minerals (phosphorus, potassium and manganese). SCC had a total phenolic content of 6.74 g GAE kg⁻¹ dry weight (DW), of which bound phenolics were predominant. The bound phenolics fraction showed the highest antioxidant capacity in all three antioxidant capacity assays (TEAC, FRAP and DPPH) and contained the highest amount of ferulic and p-coumaric acid. The main carotenoids present in SCC were β-carotene, zeaxanthin and lutein. This investigation shows that SCC can be a potential source of natural colorant (carotenoids), antioxidants (phenolics) and nutritional supplements (proteins and phytochemicals).     

Effects of in vitro simulated digestion on the free and bound phenolic content and antioxidant activity of seven species of seaweeds

The effects of simulated gastrointestinal digestion on the content and antioxidant activity of phenolics of seven seaweeds were investigated: Two methods of digestion were used – simulated gastric fluid (SGF) and simulated intestinal fluid (SIF) to mimic the stomach and upper intestinal environment. Results showed that SIF can significantly increase the free phenolic content of all tested seaweeds. The total phenolic content of the seaweeds increased in range from 4.16 to 17.24 mg GAE/g before simulated digestion to 4.08 to 40.37 mg GAE/g after digestion. The antioxidant activity of seaweed-bound phenolics was superior to that of free phenolics. Among the seven varieties of seaweeds, Sargassum thunbergii and Sargassum kjellmanianum contained the highest content of bound phenolics after SGF digestion. Bound phenolics of Undaria pinnatifida and Sargassum thunbergii showed the highest in vitro ABTS⁺ free radical scavenging ability, while Sargassum thunbergii and Sargassum fusiforme showed the highest in vitro FRAP antioxidant activity.     

Composition and Structure of Fat Globule Surface Layers in Recombined Milk

Protein coverage, composition and structure of surface layers of fat globules in recombined milk were determined. Average protein load was ～6 mg/m² fat surface. Both casein and whey proteins were present in the fat globule surface layer, with casein adsorbed in preference to whey proteins and α_s (α_sl+α_s2)-casein adsorbed in preference to β-casein. Transmission electron microscopy showed that the surface layer of fat globule was made up of casein micelles, fragments of casein micelles and a thin layer of protein, possibly whey proteins. Experiments with surface layers that had been dispersed in EDTA showed that the extent of dissociation of caseins followed the order: β-casein > α_s-casein ≦ K-casein, suggesting that most of the K-casein was probably associated directly with the fat surface.     

大分子蛋白界面修饰改善乳液特性研究进展

蛋白界面修饰指在乳液的乳化后阶段直接针对界面蛋白进行的修饰技术,其通过改变界面蛋白膜厚度或提升其强度从而改善乳液理化特性,并可一定程度规避乳化前预修饰蛋白对于乳液特性的某些不良影响,但是截至目前,对于蛋白界面修饰领域仍缺乏深入研究及系统总结。基于此,本文综述了目前研究较为广泛的几种蛋白界面修饰方法,包括酶促交联修饰、多糖修饰、多酚修饰以及氧化修饰,同时阐述了各种方法的作用机制以及对乳液特性的改善效果,并对蛋白界面修饰的未来发展方向作出展望,以期为乳液品质的进一步提高提供理论参考与技术支持。     

Atomic force microscopy as a nanoscience tool in rational food design

Atomic force microscopy (AFM) is a nanoscience tool that has been used to provide new information on the molecular structure of food materials. As an imaging tool it has led to solutions to previously intractable problems in food science. This type of information can provide a basis for tailoring food structures to optimise functional behaviour. Such an approach will be illustrated by indicating how a basic understanding of the role of interfacial stability in complex foods systems can be extended to understand how such interfacial structures behave on digestion, and how this in turn suggests routes for the rational design of processed food structures to modify lipolysis and control fat intake. As a force transducer AFM can be used to probe interactions between food structures such as emulsion droplets at the colloidal level. This use of force spectroscopy will be illustrated through showing how it allows the effect of the structural modification of interfacial structures on colloidal interactions to be probed in model emulsion systems. Direct studies on interactions between colliding soft, deformable droplets reveal new types of interactions unique to deformable particles that can be exploited to manipulate the behaviour of processed or natural emulsion structures involved in digestion processes. Force spectroscopy can be adapted to probe specific intermolecular interactions, and this application of the technique will be illustrated through its use to test molecular hypotheses for the bioactivity of modified pectin molecules. Copyright © 2011 Society of Chemical Industry