来源与加工方式对β-葡聚糖理化特性的影响及其在肠道的降解机理

检索、归纳并分析近年来关于谷物和微生物中β-葡聚糖结构、功能特性及加工方式对其的影响,以及其在肠道中的降解机理和代谢途径的研究文献。综合显示,谷物中β-葡聚糖的分子质量及β-1,3/β-1,4的比例是决定其结构与性质的关键因素,微生物β-葡聚糖多为β-1,3和β-1,6糖苷键构成的支链多糖;加工方式可改变β-葡聚糖的分子质量、溶解性、黏度及功能特性;β-葡聚糖在生物体中,由肠道厌氧微生物酶系统逐步分解为短链脂肪酸,从而起到维持肠道菌群生态平衡、改善机体代谢及调节免疫的作用。该文综合论述了加工方式,对β-葡聚糖生物活性的影响机理对β-葡聚糖的开发提供参考。     

肠道黏膜免疫屏障及其菌群与机体健康关系的研究进展

肠黏膜屏障对于防止肠腔内细菌、食物抗原、酶和化学药物等直接与黏膜裸露面接触而引起疾病至关重要,其免疫屏障对机体的健康作用越来越被人们重视.黏膜免疫系统不仅具有一般性的屏障作用,而且还参与体液免疫和细胞免疫过程,在机体肠道内环境的调节中起重要作用.随着更深入的研究,人们可能会找到新的维持机体健康的途径.本文对肠道黏膜免疫调控机理、肠道菌群及营养物质对肠黏膜屏障功能的影响,以及肠黏膜屏障受损对机体健康的危害等方面进行了综述.     

益生菌胞外蛋白与肠道粘膜免疫细胞互作关系的研究进展

近期国内外研究证实了益生菌分泌的胞外蛋白具有增强粘膜屏障、调节免疫、维持肠道稳态的功能,在一定程度上可以改善、缓解和治疗肠道疾病。益生菌分泌的胞外蛋白对肠粘膜免疫作用及对机体健康的影响的相关阐述已成为人们关注的热点,为探究益生菌对肠粘膜屏障及粘膜免疫信号通路的功能表现的分子基础,本文首先概括肠粘膜系统及其免疫机制和益生菌分泌胞外蛋白的作用,然后重点介绍国内外对分泌胞外蛋白的益生菌的相关研究进展,并指出胞外蛋白将在一定程度上打通肠粘膜免疫信号通路途径,发挥治疗肠道疾病的作用,从而达到维护肠道健康的目的,也为解决肠道健康问题提供了一条可行的途径。     

巴氏杀菌发酵乳改善DSS诱导结肠炎小鼠症状的研究

本研究采用3.5%的葡聚糖硫酸钠(DSS)构建小鼠结肠炎症动物模型,旨在阐明巴氏杀菌发酵乳对结肠炎小鼠的缓解作用及可能的机制。通过评估小鼠疾病活动指数(disease activity index,DAI),HE染色观察结肠组织病理切片,气相色谱-质谱联用(GC/MS)分析肠道短链脂肪酸含量,ELISA检测结肠组织中的炎症因子水平,检测髓过氧化物酶(MPO)含量和采用免疫组化进行紧密连接蛋白的表达,来研究巴氏杀菌发酵乳的作用。结果表明,巴氏杀菌发酵乳可以降低结肠炎小鼠疾病活动指数DAI、缓解结肠组织损伤、增加小鼠肠道短链脂肪酸乙酸、异丙酸、戊酸和总酸的含量,同时降低小鼠促炎细胞因子肿瘤坏死因子-α(TNF-α)、白细胞介素-1β(IL-1β)的分泌、增加抗炎细胞因子白细胞介素-10(IL-10)的分泌和降低MPO活性。进一步的研究表明,巴氏杀菌发酵乳可以增加小鼠肠道紧密连接蛋白的表达,增强肠道上皮屏障功能。因此,巴氏杀菌发酵乳可以缓解小鼠肠道炎症症状,并且可能是通过调节免疫功能和增强肠道屏障发挥其作用。     

结合态多酚改善肠道氧化应激与肠道屏障的研究进展

食品中富含种类丰富的酚类化合物,并且酚类化合物是天然的抗氧化剂和重要的功能因子。结合态多酚是酚类化合物的一种存在形式,其存在于提取过游离态多酚的残渣中,通过酯键、糖苷键、醚苷键等形式与其他物质相结合。肠道作为人体免疫防御的最前线,易遭受外源性和代谢性氧自由基损伤,诱发肠道氧化应激。肠道氧化应激会通过多种途径破坏肠上皮细胞间的紧密连接状态,导致肠上皮屏障功能受损和肠道通透性增加,进而诱发各种疾病。结合态多酚作为一种天然的抗氧化剂,在肠道中具有较完整的结构和稳定的活性,并通过调节免疫功能,以及影响炎症因子、抗氧化酶和屏障蛋白的表达,对肠道氧化应激以及肠道屏障功能的受损均有着改善作用。     

非淀粉多糖对肠道菌群的调节作用及其对代谢疾病影响的研究概述

膳食纤维中的非淀粉多糖（non-starch polysaccharides,NSPs）是由若干个单糖通过糖苷键连接而成的多聚体,包括纤维素、半纤维素、果胶、树胶、β-葡聚糖、果聚糖以及半乳糖等低聚糖。NSPs无法被机体消化或难以消化,因此它们几乎能完整地通过肠道,并被肠道内的微生物菌群发酵选择性地刺激肠道内微生物的增殖和活性,从而改善肠道菌群的环境。肠道微生物菌群在代谢综合征的发病机制中发挥着重要作用,通过使用益生元或益生菌来控制肠道微生物菌群,可以减少肠道低度炎症,改善肠道屏障的完整性,从而改善代谢平衡,促进减肥。因此NSPs改善肠道菌群的同时,也调节代谢疾病。该文总结NSPs与肠道菌群相互作用及改善代谢疾病的研究进展,为今后NSPs的利用提供参考。     

燕麦β-葡聚糖调节肠道菌群与降脂减肥作用的研究进展

近年来,超重和肥胖已成为许多国家突出的健康问题,其导致的一系列代谢类疾病死亡率远高于其他疾病。越来越多的证据表明,肥胖的发生与肠道菌群的组成密切相关。燕麦β-葡聚糖不仅具有显著的降血脂作用和减肥功效,还可以作为益生元调节机体肠道菌群结构。本文从肠道菌群与肥胖的相关研究、燕麦β-葡聚糖降脂减肥和益生元作用等方面综述了燕麦β-葡聚糖调节肠道菌群及其减肥降脂作用之间相关性的研究现状。     

燕麦β-葡聚糖功能与应用研究进展

燕麦β-葡聚糖是来源于燕麦糊粉、亚糊粉和胚乳组织细胞壁中的无分支线性多糖,属于水溶性纤维,是燕麦中重要的活性成分.燕麦β-葡聚糖作为一种天然的食品添加剂,在食品和医药工业得到广泛的应用.本文概述燕麦β-葡聚糖抗糖尿病、降低胆固醇、增强免疫、抗癌等生理功能及其在胃、肠道中发挥的积极作用,并综述燕麦β-葡聚糖近几年在肉类、...     

猴头菇β-葡聚糖促进人肠道菌群产丁酸的研究进展

丁酸是结肠上皮细胞首选能量来源, 可提高肠屏障的完整性, 促进人的肠道健康。已有关于猴头菇β-葡聚糖(HEBG)促进人肠道菌群产丁酸的作用的报道，但有关其调控机制还不清楚。作者介绍了HEBG的制备方法及获得的具有不同结构特征的HEBG，并对人粪便中产丁酸特性的菌群进行了总结，最后综述了不同来源β-葡聚糖调控肠道菌群产丁酸的机制及研究进展。猴头菇β-葡聚糖是一种优良的膳食纤维，它可能通过直接或间接模式促进人肠道菌群产丁酸。本综述对猴头菇β-葡聚糖益生功能的开发及健康食品的创制具有指导性意义。     

益生菌和粪菌移植调节炎症性肠病的研究进展

炎症性肠病（inflammatory bowel diseases,IBD）是一种易复发的慢性胃肠道炎症性疾病,近年来在世界范围内的发病率逐渐上升。IBD的发病因素复杂,主要是由遗传、环境、免疫等因素相互作用导致的,随着宿主-肠道微生物相互作用的深入研究,人们发现肠道菌群在IBD的进展中发挥着重要作用,因此基于调节肠道微生物群缓解或治疗IBD的新型方法也备受关注。近年来的大量研究都表明益生菌、粪菌移植可以通过调节肠道微生物的组成、增强肠道屏障功能、调节机体免疫反应等达到缓解IBD的目的。因此,本文对IBD的发病因素以及益生菌、粪菌移植调节IBD的研究进展进行综述。     

大米过敏的研究进展

食物过敏是机体针对摄入的食物产生的一种有害的、具有复发性的特定免疫反应,能够引起食物过敏反应的物质称为食物过敏原,食物中含有的致敏蛋白是引发食物过敏反应的一大来源。大米是世界上公认的最重要的粮食作物之一,全球约有一半以上的人口以大米为主食。大米蛋白占大米总量的8%~10%,含有丰富的必需氨基酸,易于被人体消化吸收,是公认的谷类蛋白中的上佳者。传统上认为,大米是低致敏性谷物,已被广泛应用于婴幼儿及配方食品中,但近年来的研究表明,大米也可引发食物过敏反应,可诱发过敏性皮肤炎、过敏性荨麻疹等症状,严重者还可引起过敏性休克。本文从大米过敏的流行性分布、主要的大米过敏蛋白以及过敏蛋白的检测方法等方面阐述了大米过敏的研究进展。     

An Enzymatic Method for the Determination of Yeast Cell Wall Glucan in Foods

Processed cell wall β-glucans prepared from strains of baker's or brewer's yeast can be used as a thickening agent in aqueous food systems and they provide a fat-like mouthfeel. This article describes an analytical procedure for the determination of the glucan content added to a variety of food products. The method is based on measurement of reducing sugars produced when the food sample, after appropriate pretreatment, is treated with a commercial microbial β-glucanase (Zymolyase) that is specific for the β-linkages present in the glucan polysaccharide of the added yeast cell walls.     

Preparation of spent brewer's yeast β-glucans for potential applications in the food industry

A preparation of β‐glucan, obtained from spent brewer's yeast, was evaluated for potential food applications. This material was autolysed and the cell walls that were obtained were homogenized, extracted firstly with alkali, then with acid, and then spray dried. Effects of the homogenization on the chemical composition, rheological properties and functional properties of β‐glucan were investigated. Homogenized cell walls exhibited higher β‐glucan content and apparent viscosity than those which had not been homogenized because of fragmentation of the cell walls. When compared with commercial β‐glucan from baker's yeast, it was found that the β‐glucan obtained from this study had higher apparent viscosity, water‐holding capacity and emulsion stabilizing capacity, but very similar oil‐binding capacity. These findings suggest that β‐glucan obtained from brewer's yeast can be used in food products as a thickening, water‐holding, or oil‐binding agent and emulsifying stabilizer.     

Assessment of Enzymatic Endosperm Modification of Malting Barley Using Individual Grain Analyses

Enzymatic modification of the endosperm of malting barley is a main feature of the malting process. Uneven enzymatic modification of the endosperm (heterogeneity) can cause brewhouse problems. Although there is a general correlation between endosperm modification, beta‐glucan breakdown and endo‐beta‐glucanase development, it is based on average results from sample analyses and may conceal heterogeneity. The primary aim of this work was to use individual grain analyses to investigate factors that control endosperm modification and beta‐glucan breakdown. In terms of beta‐glucan breakdown and physical modification, the barley variety Chariot malted faster than Decanter. However, both varieties showed similar distribution of endo‐beta‐glucanase in individual grains during malting. Further work on individual grains showed that the correlation between beta‐glucan breakdown and endo‐beta‐glucanase activity was not significant. Surprisingly beta‐glucan breakdown did not always correlate with the physical modification of the endosperm. Both these findings suggest that sample analyses of beta‐glucan levels and malt beta‐glucanase activities are not reliable indicators of the degrees of which malt samples are modified during malting. Since the distribution of beta‐glucan in individual grains of the unmalted barley varieties was similar, the total beta‐glucan levels of the original barley did not determine the rate at which beta‐glucan was broken‐down during malting. Although protein studies are at a preliminary stage, the rate of protein breakdown was not correlated with the rate at which beta‐glucan was broken down in the malting grain. It is possible that the physico‐chemical properties of endosperm storage proteins may limit the rate of beta‐glucan breakdown during malting.     

儿童食物过敏及其饮食干预治疗研究进展

食物过敏是指由人体免疫系统介导的食物不良反应,常见皮肤、消化道、呼吸道症状,如特应性鼻炎等疾病,严重会出现休克等现象。儿童作为食物过敏易感人群,其生长发育极易受到影响,并且近年来全球儿童食物过敏人群逐年增长,因此对于儿童食物过敏进行预防和治疗有着十分重要的意义。但目前关于儿童食物过敏的流行病学资料仍然比较缺乏,通过查阅中英文文献,本文对儿童食物过敏的常见致敏食物、过敏机制、发病因素及诊治方法进行综述,为食物过敏的预防和治疗方向提供一定的理论依据。     

玉米中的过敏原及物理加工对食品致敏性的影响研究进展

随着食用玉米的人群越来越广泛,玉米过敏问题日渐凸显。对玉米过敏的有效防御被人们所重视,加工通过改变过敏原的蛋白结构可以使过敏原致敏性降低。其中食品加工对过敏原致敏性的研究主要集中在热处理方面;然而各种非热方法,如微波、超高压等食品加工新技术,在降低食品的致敏性方面也有广阔的应用前景。相比来说非热方法通常是有利的,它们能够保留在热处理过程中经常改变的感官特性,如营养成分和风味。本文综述了玉米过敏原研究现状,总结了玉米中的过敏原,描述了对食物进行热处理和非热处理在改变食物过敏原反应性方面的作用,并且提出多种加工方式联合使用来降低玉米过敏原致敏性的未来研究方向,为玉米过敏的防御提供参考。     

食物过敏原介导食物过敏机制研究进展

目前食物过敏已成为严重危害成人、儿童健康的公共卫生问题且发病率呈逐年上升的趋势。食物过敏可引起严重的不良反应甚至导致死亡, 但目前针对食物过敏尚无有效的治疗方法, 只能通过食物规避或针对食物过敏症状进行相应的治疗。由于复杂的环境和遗传因素, 食物过敏的致病机制尚不清晰。本文就近年来食物过敏致病机制研究的进展进行综述。     

Impact of dietary factors and food processing on food allergy

Allergic reactions to food can significantly reduce the quality of life and even result in life‐threatening complications. In addition, the prevalence of food allergy has increased in the last decades in industrialized countries and the mechanisms underlying (increased) sensitization are still not fully understood. It is believed that the development and maintenance of oral tolerance to food antigens is a process actively mediated by the immune system and that this reaction is essential to inhibit sensitization. Ongoing research indicates that different dietary factors also may contribute to immune homeostasis and oral tolerance to food and that food processing modulates allergenicity. One of the major questions in food allergy research is therefore which impact nutrition and food processing may have on allergenicity of food and perhaps on sensitization. We summarize in this review the different dietary factors that are believed to contribute to induction of oral tolerance and discuss the underlying mechanisms. In addition, the functional consequences of allergen modification will be emphasized in the second part as severity of allergic reactions and perhaps sensitization to food is influenced by structural modifications of food allergens.     

The effects of steaming and roasting treatments on β‐glucan,lipid and starch in the kernels of naked oat (Avena nuda)

BACKGROUND: Normal pressure steaming (NPS), autoclaved steaming (AS), and hot‐air roasting (HAR) are widely used to deactivate oat enzyme in the oat‐processing industry. Infrared roasting (IR) is a new oat deactivation method, and is welcomed and employed by increasing numbers of oat‐processing plants in China. It is widely known that oat starch plays an important role in the processing function of oat food, and that oat β‐glucan and lipid contribute greatly to the health benefits of oat food. However, the effects of steaming and roasting treatments on the starch, β‐glucan and lipid in oat kernels are poorly known. RESULTS: In this research, the level and distribution of β‐glucan and lipid in oat kernels with and without deactivation treatments were tested. We also measured the viscosity properties of oat flour from kernels after NPS, AS, HAR and IR treatments, and examined the effects of these treatments on oat starch granularity using scanning electron microscopy. The results showed that the deactivation treatments did not have significant effects on oat β‐glucan and lipid levels in oat kernels (P < 0.01). The distribution of β‐glucan and lipid in enzyme‐deactivated kernels was very similar to that in normal kernels. NPS, AS, HAR and IR treatments changed the shape of starch granules, crumbled large starch granules, reduced the connection between the protein network and starch granules, and improved starch gelatinization properties. CONCLUSIONS: NPS, AS, HAR and IR treatments can change the structure of oat starch granules and improve the viscosity property of oat starch without causing β‐glucan and lipid loss to oat food. Copyright © 2010 Society of Chemical Industry     

食品加工对蛋清致敏性的影响研究进展

摘要：鸡蛋是人们日常生活中不可或缺的营养品，然而，鸡蛋也是最常见的引起过敏反应的食物之一。婴儿和儿童是鸡蛋过敏的高发人群，鸡蛋过敏反应主要是由血清免疫球蛋白E（IgE）介导的，引发皮肤、消化道、呼吸道相关的症状，甚至可导致危及生命的严重过敏反应。鸡蛋过敏目前尚无特效治愈方法，患者严格避免摄入鸡蛋成分被认为是最有效的预防手段，但严格避食会影响患者的生活质量和膳食营养，且因意外摄入鸡蛋过敏原导致过敏症状出现的情况屡屡发生。可见在鸡蛋过敏的应对方面，迫切需要新的有效方法。食品加工技术作为从鸡蛋致敏的源头上控制过敏反应的方法，近年来发展迅速。本文综述了各种常见食品加工方法对蛋清致敏性的影响，为后续开发低致敏鸡蛋产品提供思路。