牛乳酪蛋白源生物活性肽研究进展

乳酪蛋白源生物活性肽以其良好的消化性、低敏性及生物活性而日益受到重视。综述国内外在牛乳酪蛋白来源的阿片肽、阿片拮抗肽、ACE抑制肽、免疫调节肽和矿物元素结合肽等方面的研究,旨在为更好地利用牛乳酪蛋白源的生物活性肽提供参考。     

酪蛋白胃肠模拟水解液活性检测及细胞吸收机制初步研究

目的:研究牛乳酪蛋白在胃肠模拟水解条件下水解物的生物活性,以及这些肽类在细胞水平的吸收机制,为蛋白质生理作用机制研究奠定基础。方法:以牛乳酪蛋白为原料,对其进行体外模拟胃肠消化实验,通过检测消化液的DPPH自由基清除率和抑菌圈大小,分析其抗氧化和抗菌活性;建立Caco-2单层细胞模型对水解液进行过膜吸收,RP-HPLC分析过膜前后消化液组成,研究吸收情况。结果:模拟胃和肠消化时间均在2 h时,牛乳酪蛋白消化液的DPPH自由基清除率达到最大,分别为46.40%和56.7%,并且此时对大肠杆菌和金黄色葡萄球菌抑菌性能最强;细胞吸收实验表明2 h胃模拟水解液肽氮生物利用度达到7.79%,2 h肠模拟水解液达到15.11%,之后基本持平;亲水性的多肽能被成功吸收进入单细胞层下侧,但疏水性多肽大部分不易通过,易被降解或阻止。结论:牛乳酪蛋白在模拟消化条件下能产生生物活性肽类,并能被肠细胞吸收。     

酪蛋白糖巨肽的生理功能及发展前景

酪蛋白糖巨肽（casein Glycomacmpepride，简称CGMP）是一种含有唾液酸的糖肽，用凝乳酶或酸性蛋白酶水解牛乳酪蛋白（主要是K-酪蛋白），乳清中含有CGMP。简述CGMP的化学结构、制备、检测方法、生物活性、研究现状及应用前景。     

乳酪蛋白源免疫调节肽

酪蛋白是乳中最主要的蛋白质 ,除了提供氨基酸和能量的营养功能外 ,酪蛋白还是生物活性肽的重要来源。这些生物活性肽本身以非活性状态存在于蛋白质氨基酸序列之中 ,当用适当的蛋白酶进行体外水解或在胃肠道消化过程中以及食品加工过程中 ,它们的活性就被释放出来 ,并可作为生理功能的重要调节剂。大量证据表明乳酪蛋白中存在大量的免疫调节肽。本文对乳酪蛋白来源的免疫调节肽的序列结构及其对免疫系统的调节机能做一综述。     

牦牛乳酪蛋白肽制备及乙酰化脱苦

采用碱性蛋白酶对牦牛乳酪蛋白进行水解,得到牦牛乳酪蛋白肽.以醋酸酐为酰化试剂,利用结构修饰的方法对牦牛乳酪蛋白肽进行脱苦研究,探讨醋酸酐添加量、pH对牦牛乳酪蛋白肽酰化度及苦味的影响.结果显示,碱性蛋白酶最佳水解条件为,温度55℃,pH7.0,酶添加量1.25％,反应3h.维持酰化反应pH7以上,产物乙酰化程度最高,醋酸酐的添加量与脱苦效果呈正比,当醋酸酐添加量为40％时,牦牛乳酪蛋白肽酰化产物的苦味基本消失.     

低矿化牛乳酪蛋白胶束与婴幼儿蛋白质胃肠消化的关系

蛋白质消化吸收对生命早期的生长发育至关重要，牛乳酪蛋白胶束矿化水平是影响婴幼儿蛋白质胃肠消化的重要因素。目前，乳制品加工业中常用的降低酪蛋白矿化水平的方法有离子交换脱钙法、螯合脱钙法和酸化脱钙法。低矿化牛乳酪蛋白能增加蛋白质溶解性、抑制蛋白凝胶形成、提高酪蛋白体外胃肠消化速率。研究发现，低矿化牛乳酪蛋白通过改变酪蛋白胶束结构，导致酸性环境和胃蛋白酶作用下形成的絮凝颗粒小且疏松，加速酪蛋白在胃中的分解和消化速率，能够帮助改善婴幼儿蛋白质胃肠消化问题，提高婴幼儿胃肠舒适度。文章旨在为婴幼儿配方奶粉选用低矿化牛乳酪蛋白胶束作为配料改善婴幼儿胃肠消化提供营养学理论支持。     

酶法制备牦牛乳酪蛋白源血管紧张素转换酶抑制肽

应用6种商业蛋白酶水解牦牛乳酪蛋白,研究其水解产物的血管紧张素转换酶抑制活性,结合蛋白水解度及蛋白回收率的结果,蛋白酶C适用于制备牦牛乳酪蛋白源血管紧张素转换酶抑制肽。     

基于多重光谱技术的木糖醇与牛乳酪蛋白相互作用及对酪蛋白结构的影响

综合利用荧光光谱法、傅里叶变换红外光谱法和圆二色谱法等多种先进光谱技术研究木糖醇与牛乳酪蛋白的相互作用以及对牛乳酪蛋白二级结构及功能性质的影响。荧光光谱表明,木糖醇对牛乳酪蛋白具有较强的荧光猝灭效应,猝灭机理属于静态猝灭,生成了新的复合物,二者在300、310 K和320 K时相互作用的结合常数分别为5.326×106、2.600×106 L/mol和2.160×106 L/mol,对应的结合位点数分别为1.513、1.452和1.422,主要作用力为静电引力,可能会有疏水作用力,结合距离为3.564 nm;同步荧光光谱和三维荧光光谱的结果表明,二者的相互作用位点更接近于色氨酸,其周围微环境的疏水性增强,使酪蛋白的分子构象发生改变;傅里叶变换红外光谱和圆二色谱的结果表明,木糖醇改变了牛乳酪蛋白的二级结构,使其α-螺旋结构相对含量增加,无规卷曲结构相对含量减少,结构变得更加紧密;结构的变化导致酪蛋白的乳化活性降低,乳化稳定性升高,表面疏水性降低。研究结果为功能性乳基料的开发提供了理论依据。     

牛乳酪蛋白抗氧化乳基料的制备及其分离纯化

为制备具有低过敏性和抗氧化作用的牛乳酪蛋白活性肽乳基料,以水解度和·OH清除率为指标,先后采用大孔吸附树脂和凝胶过滤色谱分离、纯化酪蛋白酶解物。结果表明：胰蛋白酶和中性蛋白酶组合酶解牛乳蛋白6h,其产物具有较高的水解度(36.80%)和较好的抗氧化活性,·OH清除率的半抑制浓度(IC50)值为3.12mg/mL;酶解物通过LS106大孔吸附树脂分离、纯化后,体积分数为75%的乙醇洗脱液具有较高的抗氧化活性,其·OH清除率的IC50值为0.14mg/mL;体积分数75%的乙醇洗脱组分经凝胶过滤色谱分离、纯化后,得到4个不同相对分子质量肽段,其中抗氧化活性较强肽段的相对分子质量为355.38～854.89,其·OH清除率的IC50值为0.09219mg/mL,与酶解物相比其抗氧化活性扩大33.84倍;相对分子质量小于3238.05的多肽占纯化后多肽总量的60.32%,30.09%多肽是由2～8个氨基酸组成的寡肽。牛乳酪蛋白经复合酶酶解后其抗氧化活性明显提高,过敏性明显降低,喷雾干燥后可以直接制备乳基料。     

山羊乳酪蛋白酶解工艺及抗氧化性研究

为了制备山羊乳酪蛋白活性肽,选用中性蛋白酶、胰蛋白酶、木瓜蛋白酶和碱性蛋白酶,采用对比和正交试验方法,研究了山羊乳酪蛋白单酶和复合酶的酶解工艺,测定了山羊乳酪蛋白的总肽键摩尔数,优选出了山羊乳酪蛋白的酶解工艺参数。结果表明：山羊乳酪蛋白的总肽键摩尔数为8.5379 mmol/g。单酶中胰蛋白酶和中性蛋白酶对山羊乳酪蛋白的水解度较大,木瓜蛋白酶较小。胰蛋白酶对山羊乳酪蛋白适宜的酶解工艺：加酶量2500 U/g,pH 7.5,50 ℃下酶解2 h。中性蛋白酶和胰蛋白酶复合以及中性蛋白酶、胰蛋白酶和木瓜蛋白酶三种酶复合的水解度较大,其水解度、平均肽链长度和平均相对分子量分别为17.34%、21.16%,5.77、4.73和692、567 u。     

虾类抑制黑变保鲜技术研究进展

虾类中因富含大量人体必需氨基酸、微量营养素而备受关注。本文介绍了虾类的基本信息及其在储藏加工过程中主要存在的黑变问题和机制,以及各种虾保鲜、抑制黑变的方法。首先介绍了化学方法,包括现阶段正在使用或已被研究的化学合成试剂及天然试剂的作用机制及相关研究。主要的化学合成试剂有乙二胺四乙酸、4-己基间苯二酚、亚硫酸盐、焦亚硫酸钠、氯化钠等。天然试剂主要包括抗坏血酸、植酸、阿魏酸、曲酸、麦角硫因、儿茶酚、葡萄籽、竹叶抗氧化物、茶黄素、壳聚糖、紫菜多糖、鳄梨等;物理方法包括调控温度、气调保鲜、辐射、可食用性涂抹材料、冰保鲜冰、压力调控、臭氧等;其他新兴方法包括乳酸菌法、饥饿法、酸性电解冰法等。还介绍了近几年应用于虾保鲜的综合应用方法,如冷藏和气调保鲜技术相结合,用壳聚糖包裹再添加石榴皮提取物,用橙子油和明胶复配,焦亚硫酸钠和绿茶与迷迭香提取物的同时使用,壳聚糖与虾蛋白脂浓缩物等;最后提出对于新型廉价的保鲜方式的开发,各种天然抑制剂的研究,以及将2种或2种以上试剂进行搭配使用以取得更好的协同效果的研究将成为今后虾保鲜抑制黑变的热点。     

甘蔗的生物炼制--蔗渣综合利用新进展

当今甘蔗糖业出现种蔗面积趋少、劳力短缺劳工报酬升高、作物竞争等因素使蔗价目益攀高占食糖生产成本趋大的情况。糖价则受国际市场、淀粉糖、甜味剂的冲击波动较大,若企业只单一生产糖产品存在风险,威胁持续发展。总结我国过去经验,有综合利用产品的企业抗风险力较强、经济效益较好。国际上也鉴于地球资源和能源的日渐稀缺以及环境的日益恶化...     

Microstructure design in mixed biopolymer composites

This paper is an overview of recent work on some particular aspects of the behaviour of biopolymer solution and gel mixtures, the focus being on aspects that are of particular relevance to the materials found in food systems. As such, the following areas are considered. (1) The phase behaviour of such mixtures in terms of the microstructures formed, the ideas of phase volume, phase continuity, surface tension and the use of the Flory–Huggins theory to model the behaviour. (2) The kinetics of phase separation in terms of the evidence for spinodal decomposition, ripening processes and the interplay between the kinetics of phase separation, gelation and molecular ordering. (3) The effects of shear on the composite microstructure in terms of particle size and shape, and how shear can be used to cause phase inversion of the system. (4) The material properties of the composites, including the fracture behaviour, the effect of particle size, and the role of the interface between the phases. It is clear that over the past few years a considerable literature has been built up on mixtures of biopolymers. Despite this growing understanding it remains a fact that we are not capable, as yet, of designing the microstructure of mixed biopolymer composites, although it is clear that there is a considerable technological advantage in being able to do so.     

Influence of laboratory homogenization procedures on trace element content of food samples: an ICP-MS study on soft and durum wheat

Sample contamination as a consequence of abrasion of grinding tools during the homogenization of food materials to be analysed for trace elements was addressed. The possible release of 15 trace elements (Al, As, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Se, Sn, V, Zn) from six different grinding and milling devices, operating either continuously or discontinuously, was evaluated. All the devices were commercially available and were representative of models usually employed in food and agricultural laboratories. Wheat grains belonging to one soft and one durum cultivar were used as test material. The determination of the analyte concentrations in subsamples submitted to the different preparation treatments was performed by quadrupole inductively coupled plasma mass spectrometry (Q-ICPMS). Accordingly, a suitable digestion method was developed and the ArC⁺ interference affecting Cr determination was evaluated and corrected. Statistical differences with respect to the control were detected for 10 elements (Al, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb) and in most cases contamination of the samples was traced back to the composition of the grinding equipment. None of the investigated devices was contamination-free with respect to all of the quantified elements. Abrasion of the grinding tools was higher with durum wheat than with soft wheat as a consequence of their different hardness.     

多糖类食品添加剂对米饭质构特性的影响

通过扫描电镜分析,得出仙桃大米颗粒的孔隙大小为2μm 4μm;采用90Plus Particle Size Ana-lyser分析羟丙基甲基纤维素(HPMC)、麦芽糊精、瓜尔豆胶和卡拉胶在水溶液中的粒径分布大小,得出这些多糖类食品添加剂在水溶液中的粒径大小分别为897.7nm、35.9nm、125.2nm、323.5nm。在蒸制米饭的过程中添加这些多糖类食品添加剂,研究米饭样品在冷藏过程中的硬度和黏性的变化,结果表明:羟丙基甲基纤维素(HPMC)和瓜尔豆胶添加量为0%时,与添加量为0.1%,0.3%的米饭样品相比,米饭的硬度较低,而黏性则较高,添加羟丙基甲基纤维素和瓜尔豆胶加速了米饭样品的老化;麦芽糊精和卡拉胶添加量为0.1%的米饭样品与添加量为0%和0.3%的样品相比,米饭样品的硬度低于而黏性高于添加量为0%和0.3%的米饭样品,麦芽糊精和卡拉胶能够起到延缓米饭样品老化的作用。     

Genotypic and climatic influences on the concentration and composition of flavonoids in kale (Brassica oleracea var. sabellica)

The aim of this study was to determine the composition and concentration of flavonoid aglycones in kale, the dependence on genotype and their interaction with decreasing temperature and global radiation. Eight kale cultivars, comprising hybrid and traditional, old cultivars, were grown in a field experiment and harvested four times at 4-week intervals. The traditional, old cultivars in particular contained high concentrations of flavonoids. In all of the investigated cultivars, kaempferol was the main flavonoid aglycone, followed by quercetin and isorhamnetin, which was quantified in six of the eight cultivars. Furthermore, in six of the eight cultivars, the total concentration of flavonoids remained unchanged with decreasing temperature and global radiation. The quercetin concentration increased in five of these six cultivars, whereas the kaempferol concentration decreased. Interestingly, the quercetin-to-kaempferol ratio increased in all of the investigated cultivars, despite the fact that the radiation level decreased, suggesting that the impact of the decline in temperature could be responsible for this effect.     

Drying kinetics of plant products: Dependence on chemical composition

Kinetics of drying and soaking of fruits and vegetables (apples, pears, grapes, apricots, carrots, tomatoes, peppers, garlic, onions, peas, spinach, pumpkins, mushrooms, oats, perennial ryegrass, and beans) were investigated. The rate constants and the activation energies of drying/soaking were calculated with the use of the initial and final portions of the corresponding kinetic curves. The dependence of the drying kinetics upon the chemical composition of the material was explained with the help of the diffusion model. Within it the plant tissue was modeled by a diffusion membrane and Fick’s law was utilized.     

Decontamination methods to prolong the shelf-life of minimally processed vegetables, state-of-the-art

Minimally processed vegetables (MPV) are any fresh vegetables that have been physically altered from their original form, but remains in a fresh state. Microorganisms present in MPV can cause foodborne illnesses or spoilage; hence, decontamination of MPV can produce more stable products. The present review examines the difficulties to decontaminate and prolong the shelf-life of MPV, evaluating the current way of data analysis and interpretation. It addresses the different aspects of the problem of the accessibility of sanitizers to microorganisms (irregularities of produce surface, injuries, internalization, attachment, and biofilms). It also includes a critical exposition of the methodological problems to estimate the prolongation of shelf-life due to a decontamination method, namely: the variability among samples, the reproducibility of the results, and the interpolation when lacking some crucial data. Furthermore, it revises the difficulties to control the microbial loads of decontaminated MPV during storage (the enhanced growth rate of microorganisms in decontaminated MPV, the patterns of microbial growth in non decontaminated and decontaminated MPV, and the role of temperature in keeping the decontamination effect).     

添加木质肉的鸡肉火腿肠品质特性分析

为探究木质肉(Woody breast,WB)添加量对鸡肉火腿肠品质特性的影响及其添加的可行性,以5种不同木质肉添加量的火腿肠为研究对象,对其质构、感官、水分分布及微观结构进行检测分析。结果表明:木质肉添加量维持在50%时,火腿肠弹性、回复性、粘聚性参量最优,均达到优级火腿肠评判标准,分别为0.83、0.29、0.71,其质地、感官总评最高,分别为1.67和4.50。低场核磁显示木质肉添加量为50%时,自由水占比最低,结合水占比最高,分别为2.99%和0.78%,不易流动水基本保持不变。火腿肠微观结构随着木质肉添加量的增加由完整、清晰、分布均匀变为多孔洞、蓬松状。研究表明,将木质肉以肉糜的状态加入火腿肠具有一定可行性,且添加适量的木质肉糜对优化火腿肠品质具有一定的作用。     

Non-thermal stabilization mechanisms of anthocyanins in model and food systems—An overview

Phenolic compounds are part of the secondary metabolism of plants and are of great importance for their survival in unfavourable environment. A class of phenolic compounds easily found in the Plant Kingdom, is anthocyanins, a flavonoid category. They are water-soluble pigments that confer the bright red, blue, and purple colors of fruits and vegetables and promote several health benefits due to their diverse biological activities. Different factors affect the color and stability of these compounds including pH, temperature, light, presence of copigments, self-association, metallic ions, enzymes, oxygen, ascorbic acid, sugar, among others. For this reason many studies have been conducted with the aim to increase the stability of these substances. Therefore, the present review highlights studies on the stabilization of anthocyanins and presents latent anthocyanin stabilization mechanisms and demonstrates the potentiality of the main techniques used: association and encapsulation.