水包油乳液中油脂氧化稳定性的研究进展

随着消费者对不饱和脂肪酸及其产品营养价值越来越重视,不饱和脂肪酸富集食品已经成为食品工业发展的趋势。水包油(oil-in-water,O/W)乳液是食品油脂最常见的存在形式,也是必需脂肪酸、脂溶性营养素和风味物质的有效载体。然而,富含不饱和脂肪酸的O/W乳液食品在加工和贮藏过程中极易氧化,引起风味恶化、营养损失,甚至形成威胁人类健康的有毒化合物。因此,如何提高乳液中油脂的氧化稳定性是食品工业中亟待解决的问题。然而,消费者对天然食品需求的提高,又限制了合成抗氧化剂和氢化等传统抗氧化方法的使用。本文综述了O/W乳液中油脂氧化的机制、影响因素和调控机制,重点概述了食品分散体中油-水界面的理化性质如何影响油脂氧化稳定性这一基础研究,为高稳定性乳液体系和新型功能食品的开发提供新思路和理论支持。     

Whey protein–carboxymethylcellulose interaction in solution and in oil-in-water emulsion systems. Effect on emulsion stability

Carboxymethylcellulose (CMC) was used as coagulation aid to precipitate the whey proteins from defatted milk serum and the ability of the resulting whey protein concentrate (WPC, protein content: 63.69%) to aid in the physicochemical stabilization of oil-in-water emulsions, during ageing or following the application of heat or freeze–thaw treatment, was investigated, along with the stability of emulsion systems prepared with a commercial whey protein isolate. The stability of WPC emulsions against droplet flocculation and creaming, and to a lesser extent against droplet coalescence, depended on the presence of the CMC molecules in the emulsion continuous phase and the extent of adsorbed protein–polysaccharide interactions as affected by the emulsion pH. Studies on whey protein–CMC interaction were conducted, both in biopolymer mixture solutions and emulsion systems, by applying zeta potential measurement and viscometry techniques. These results were combined with data on protein surface hydrophobicity and on methylene blue-binding ability of CMC molecules and indicated that whey protein–CMC interaction may take place in solution, both at neutral as well as at acidic environments, leading, depending on pH, to the formation of soluble or non-soluble amphiphilic conjugates. In emulsion systems, however, conjugate formation is observed only at relatively acidic pH environments, probably because at a neutral or at a slightly acidic pH whey protein adsorption to the emulsion droplet surface and molecular unfolding does not favour protein–polysaccharide interaction.     

Modification of myofibrillar protein functional properties prepared by various strategies: A comprehensive review

Today, both consumers and food industry producers have exhibited an ever-growing interest in improving and broadening the functional performance of proteins in food industry. Myofibrillar protein (MP) is mainly responsible for texture, yield and organoleptic characteristics of final meat products. To increase functional properties of MP, technological and nutritional improvement of MP is needed to modify its structure and functionalities. Considerable approaches, including additives, oxidation treatments, and novel food processing technologies, have been utilized to modify its functional properties to manufacture acceptable meat products with lower cost and more desirable nutritional characteristics. However, a comprehensive summary of structural and functional changes of MP in response to different modification strategies is still lacking. Hence, in this review paper, our main goal is first to provide an overview of the functional characteristics of MP. Then, this review will mainly discuss the current knowledge on the functional changes of MP caused by various modification methods and will present some examples of previous works and recent progress. Finally, future outlooks are presented to tailor the manufacture of functionality enhanced and value-added muscle-based products and enable modified MP can be applied as a novel meat ingredient in food industry.     

Changes in functional properties of common carp (Cyprinus carpio) myofibrillar protein as affected by ultrasound-assisted freezing

Ultrasound-assisted freezing (UF) has proven to be a method that can effectively increase the freezing rate of frozen food and improve its quality. The functional properties of myofibrillar proteins (MP) are important factors that affect the further processing quality of meat products. At present, the effect of UF on the functional properties of frozen MP is not yet clear. Therefore, in the present study, changes in the functional properties (emulsifying and gel properties) of MP in common carps (Cyprinus carpio) frozen with UF at different power levels were investigated. The results revealed that, compared with immersion freezing (IF), UF at 175 W (UF-175) effectively inhibited the decrease in protein solubility, absolute Zeta potential, emulsion activity index, storage modulus (G'), and loss modulus (G'') caused by freezing. UF-175 sample had lower protein turbidity, and smaller protein particle size than any other frozen samples (P < 0.05), which suggested that UF-175 inhibited protein aggregation induced by freezing. In addition, shorter T₂₁ and T₂₂ relaxation times were obtained in UF-175 sample than other frozen samples, indicating that UF-175 reduced the mobility of immobilized and free water. Accordingly, UF-175 sample had higher gel strength and water holding capacity than other frozen samples (P < 0.05). A denser and more uniform gel network structure was also found in UF-175 sample than other frozen samples. In general, improved functional properties of common carp MP can be achieved by optimal UF.     

马铃薯淀粉对鲤鱼肌原纤维蛋白功能特性的影响

将马铃薯淀粉（不同添加量0%、1%、2%、3%和4%）添加到鲤鱼肌原纤维蛋白中,通过测定肌原纤维蛋白的浊度、乳化性、凝胶的硬度、弹性、保水性、白度值等指标,较为系统地研究了马铃薯淀粉对鲤鱼肌原纤维蛋白功能特性的影响。结果表明:在温度一定时,淀粉-蛋白复合物的浊度随着马铃薯淀粉添加量的增大而升高;在马铃薯淀粉添加量一定时,淀粉-蛋白复合物的浊度随着温度的升高而升高。随着马铃薯淀粉添加量的增加,乳化活力和乳化稳定性呈先上升后下降后又有所增加的趋势,在马铃薯淀粉添加量为2%和1%时乳化活性和乳化稳定性分别达到最大值25.66m2/g,90.67%。当温度相同时,淀粉-蛋白复合凝胶的硬度和弹性值随着马铃薯淀粉添加量的增大而升高,在80℃条件下,添加了4%淀粉的样品与对照组相比硬度和弹性分别提高了65.85%,20.85%,且效果显著（p<0.05）,而随着马铃薯淀粉添加量的增加,凝胶持水性增大（p<0.05）,最大增加了18.75%,但凝胶的白度值呈现下降趋势。因此添加马铃薯淀粉可以有效改善肌原纤维蛋白的功能特性。      

食用胶对猪肉肌原纤维蛋白功能特性的影响

将不同添加量的卡拉胶、亚麻籽胶、黄原胶和魔芋胶添加到猪肉肌原纤维蛋白溶液中,通过测定肌原纤维蛋白的乳化能力、凝胶质构特性、保水性和凝胶白度,研究食用胶对肌原纤维蛋白功能特性的影响。结果表明:与未添加食用胶的对照组相比,四种食用胶均可显著提高肌原纤维蛋白的乳化能力、凝胶硬度和弹性以及保水性(p<0.05),且添加量越高,增加的幅度越大;但添加食用胶后,肌原纤维蛋白的凝胶白度略有下降。因此,卡拉胶、亚麻籽胶、黄原胶和魔芋胶对肌原纤维蛋白的功能特性具有显著的影响。      

Oxidative stability of oil-in-water emulsions stabilised with protein or surfactant emulsifiers in various oxidation conditions

Many studies have investigated the effect of emulsifiers on the oxidative stability of oil-in-water (O/W) emulsions. A better oxidative stability of surfactant-stabilised O/W emulsions as compared to protein-stabilised emulsions has been recently shown in conditions when the major part of the emulsifier is adsorbed at the oil-water interface and oxidation is induced by iron−ethylenediaminetetraacetic acid (EDTA) complex. In this work, the contribution of the interfacial layer to the oxidation of emulsified lipids is investigated under various incubation conditions, involving different oxidation mechanisms. O/W emulsions were formulated at pH 6.7 with limited amounts of emulsifiers in the aqueous phase. Emulsions were incubated either at 33 °C without initiator at 25 °C in the presence of iron/ascorbate, metmyoglobin or 2,2′-azobis(2-amidinopropane)-dihydrochloride (AAPH). Oxygen uptake and volatile compound formation confirmed that protein-stabilised emulsions are less oxidatively stable than Tween 20-stabilised ones. This work also shows complex oxidative interrelationships between oxidation initiator and certain proteins, such as β-casein and bovine serum albumin.     

Effects of Agaricus bisporus on gel properties of chicken myofibrillar protein

The gel-forming ability of myofibrillar protein (MP) is highly correlated with the characteristics of emulsified meat products. Incorporation of Agaricus bisporus (Ab) powder into MP gels may enhance its gel properties to facilitate the development of a novel and safe meat product. Therefore, this study investigated the effects of Ab powder on gel strength, water holding capacity (WHC), texture, rheological behaviour, LF-NMR spin–spin relaxation (T₂), microstructure and protein secondary structure of the MP gel system. The results indicated that the gel strength, WHC, G' value and G" value were significantly improved when the addition of Ab powder increased from 0% to 6% (P < 0.05). Meanwhile, the T₂ relaxation time was shortened, and free water was transformed into immobilised water. The texture of the gel was improved when 1%–4% Ab powder was added compared to the control. Furthermore, Ab filled in the gel network and promoted the unfolding of MP α-helix and the formation of MP β-sheet during the thermal denaturation of MP, leading to a dense aggregated network structure. The study suggested that Ab could be a promising ingredient in improving chicken MP's gel properties and developing fat-reduced meat products.     

超声波处理对猪肉肌原纤维蛋白理化及乳化特性的影响

采用超声波技术对猪肉肌原纤维蛋白(myofibrillar proteins,MP)进行改性处理,研究超声功率(0,80,140,180,200W)对肌原纤维蛋白理化与乳化特性的影响。结果表明,与未经超声处理的肌原纤维蛋白比较,随着超声功率的增加,MP体积等效平均粒径(d4,3)降低,而溶解度、电位绝对值、乳化活性及乳化稳定性均显著升高。超声功率达到180W时,该处理的肌原纤维蛋白制备的乳化液表现出较高的乳化活性和乳化稳定性,乳化稳定性的提高与增加的电位和降低的平均粒径有关,光学显微镜观察发现该乳化液表现出相对较低的油滴大小。相关性分析结果表明,超声功率与d4,3极显著负相关(P≤0.01),与溶解度、电位、乳化活性及乳化稳定性显著正相关(P≤0.05)。     

Changes in physicochemical properties and myofibrillar protein properties in grass carp salted by brining and injection

The aim of this study was to investigate the changes in physicochemical properties and myofibrillar protein properties of grass carp meat during brining and brine injection at 4 °C. The time reached equilibrium was 7 h in brining group and 5 h by injection, where the salt content was about 1.76%. The water content, water holding capacity and yield in injection group (86.59%, 9.18% and 110%, respectively) were higher than brining group (84.76%, 11.47%, and 108%, respectively) at equilibrium point significantly (P < 0.05). This was attributed to the more swollen filament lattices and disordered protein structure in injection group (P < 0.05). The myofibrillar protein structure was compared, including sulphydryl content, surface hydrophobicity, solubility, sodium dodecyl sulphate polyacrylamide gel electrophoresis pattern and secondary structure. The injection group presented the better quality of salted fish meat in shorter time.     

超声波对不同盐浓度下肌原纤维蛋白溶解性的影响

应用超声波处理(频率20 kHz,功率450 W,超声波强度30 W/cm2,时间0、3、6和9 min)不同NaCl浓度(0.2、0.4、0.6 mol/L)下鸡胸肉肌原纤维蛋白(myofibrillar protein,MP),分析MP的溶解度、浊度、粒径、电位及二级结构,研究超声波处理对MP溶解特性的影响.结果显...     

Emulsion-forming properties of heat-induced pork myofibrillar protein affected by NaCl

The emulsification characteristics of myofibrillar proteins (MPs) with different NaCl concentrations also affect the quality of meat products after cooking. We investigated the effects of heating (100 °C) on the solubility, emulsifying activity, and conformational and environmental changes of MPs prepared with different NaCl concentrations. Emulsifying activity increased with increasing NaCl prior to heating, but there was no significant effect after heating. The viscosity increased and particle size decreased with increasing NaCl before heating, but these properties did not change after heating. NaCl did not affect the amount of α-helix and β-sheet. We deduced that the different emulsifying activity of myofibrillar proteins with different NaCl concentrations after heating may have been due to changes in the local environment of MPs. An understanding of the physicochemical and functional properties of MPs would unlock an area for development of meat products at different NaCl and temperature in the food industry.     

白酒对秋刀鱼肌原纤维蛋白结构和功能性质的影响

以秋刀鱼为原料,研究白酒添加量对秋刀鱼肌原纤维蛋白(Myofibrillar protein,MP)溶解度、乳化性、浊度、表面疏水性、凝胶特性和巯基含量的影响。结果表明:随着白酒添加量的增加,MP溶解度、乳化性、凝胶硬度、弹性、咀嚼性、内聚性及保水性呈先上升后下降的趋势,凝胶白度值无明显变化;浊度、表面疏水性、巯基含量呈先下降后上升的趋势。整体来看,白酒处理对秋刀鱼肌原纤维蛋白的功能特性影响较大,且在白酒添加量为5%~7%时对凝胶特性的改善效果较好。通过十二烷基硫酸钠-聚丙烯酰胺凝胶电泳研究发现,白酒能够促进蛋白质的溶解,并使溶出的蛋白质通过聚合作用形成大分子物质。     

超声改性豌豆蛋白乳状液稳定性的研究

采用超声技术对豌豆蛋白进行改性,利用单因素实验考察超声功率、超声时间和豌豆蛋白质量浓度对豌豆蛋白乳化性的影响,采用正交实验优化改性条件。通过傅里叶红外光谱和激光粒度分布仪对改性产物进行表征,采用显微镜进行微观结构观察。结果表明:豌豆蛋白超声改性最佳工艺条件为豌豆蛋白质量浓度30 mg/m L、超声时间40 min、超声功率500 W,在此条件下超声改性豌豆蛋白乳化活性(A_(500))为0. 331,乳化稳定性为72. 52%;超声改性豌豆蛋白的α-螺旋和β-转角含量减少,β-折叠和无规卷曲含量升高,表明超声改性破坏了蛋白质空间结构,进而改善了豌豆蛋白的功能性;超声改性豌豆蛋白乳状液于4℃储藏15 d无明显絮凝现象。     

Evaluation of red bean protein [Vigna angularis] isolate on rheological properties of pork myofibrillar protein gels induced by microbial transglutaminase

The effects of 1% red bean protein isolate (RBPI) on the gel properties of myofibrillar protein (MP) in various levels of microbial transglutaminase (MTG: 0%, 0.1%, 0.5%, & 1%) were evaluated. The cooking yield (CY) of the MP gels decreased with increasing MTG level, while the addition of RBPI improved the CY of the MP gels. Gel strength (GS) was also improved when RBPI was incorporated into the MP gels containing higher than 0.5% of MTG. The addition of MTG and RBPI was slightly changed the endothermic peak temperatures. Scanning electron microscopy (SEM) showed that the three‐dimensional structure of MP with RBPI alone or in combined with MTG was compacted as compared to the control. Based on the results, RBPI could be functioned as a substrate for MTG (0.5–1.0%) and a water binder of meat protein gel mediated by MTG.     

Structures and properties of chicken myofibrillar protein gel induced by microwave heating

Structures and properties of myofibrillar protein gel prepared at different power (300–800 W) were evaluated. Amino acid analysis demonstrated that changes in microwave power did not alter primary structure of gel. However, an increase in microwave power could change higher structures of gel. As microwave power increased, α-helix content decreased and β-sheet content increased. Increased microwave power probably facilitated protein to unfold and expose the internal groups, causing surface hydrophobicity and the formation of disulphide bonds were enhanced, which indicated changes in tertiary and quaternary structures of protein. At 500 W, gel had the best ultrastructure where surface morphology, springiness and water holding capacity reached the optimum. Our findings suggested that microwave at an appropriate power (500 W) could change higher structures of myofibrillar protein gel to achieve desired processing and quality protein gel characteristics.     

冷冻及解冻处理对肌原纤维蛋白理化性质的影响

研究不同的冻结温度（-18 ℃和-50 ℃）和解冻方式（微波解冻、空气解冻及4 ℃解冻）对猪肉肌原纤维蛋白含量和理化特性的影响。结果表明,在不同冻结温度与解冻方式下,肌原纤维蛋白的含量、溶解性、乳化活性、乳化稳定性、起泡性及起泡稳定性均降低,表面疏水性增加。其中,采用-18 ℃冻结,微波解冻处理的肌原纤维蛋白与对照组相比,其溶解性、乳化性、乳化稳定性、起泡性及起泡稳定性分别降低了38.7%、16.5%、28.3%、39.6%和17.3%;采用-50 ℃冻结,4 ℃解冻的蛋白其含量（6.32%）、溶解性（22.05%）、乳化性（7.89 m2/g）、乳化稳定性（32%）、起泡性（30.95%）及起泡稳定性（62.25%）与其他处理对应的各指标相比,理化特性均保持较好。不同的冷冻和解冻条件下,肌原纤维蛋白各指标之间的变化相互关联。     

Tannic acid enhanced the emulsion stability,rheology and interface characteristics of Clanis Bilineata Tingtauica Mell protein stabilised oil-in-water emulsion

Clanis Bilineata Tingtauica Mell Protein (CBTMP) was one of the new natural insect protein resources. However, due to its strong surface hydrophobicity and poor emulsion stability, its application has greatly been limited. In this study, Pickering emulsions were prepared by CBTMP–Tannic acid (CBTMP–TA) particles and soybean oil (φ = 50%). The presence of TA significantly increased the zeta-potential (from −23.5 ± 0.73 to −29.23 ± 0.58 mV) and three-phase contact angle (from 129.9 ± 4.53° to 87.27 ± 3.20°) of complex, especially the concentration of TA was 0.4 mm . Besides, the stability of emulsions was significantly improved according to the results of the droplet size and static multiple light scattering. Furthermore, rheological properties including viscosity, thixotropy and creep recovery were significantly enhanced, which indicated the formation of a more stable network structure. Interfacial behaviour (Interfacial tension, interfacial film viscoelasticity and diffusion rate) of emulsions was significantly changed, forming a more stable interfacial layer as TA content increased. The CBTMP–TA complex was adsorbed at the interface and the adsorption rate was also mainly affected by the content of TA. The study indicated CBTMP–TA compositions to enhance stability, rheological behaviours and interfacial characteristics, and demonstrated the potential applications of insect protein resources in food emulsion systems.