饮料中的蛋白-多酚混浊

了解混浊活性（ＨＡ）蛋白和多酚的性质与相互作用,有助于生产出更好的饮料产品,使用更好的分析方法及稳定手段。     

饮料中的蛋白质—多酚混浊物

引起啤酒、白酒和澄清果汁出现混浊或沉淀的原因很多,最常见的是由蛋白质———多酚的相互作用引起的,但这些饮料一般能稳定存在,并能延缓蛋白质———多酚混浊物形成开始的时间。10多年前已有关于促使蛋白质或多酚成为混浊激活物(ＨＡ)方面的报道(Ａｓａｎｏｅｔａｌ,1982;Ｍｏｌｌ,1987),但近来的研究发现,饮料中两者的比例对混浊的形成数量起着重要的作用(Ｓｉｅｂｅｒｔｅｔａｌ,1996ｃ),这发现使我们能更好地理解一些检测ＨＡ种类的分析方法及其稳定的机制。在鉴别ＨＡ物质的特性方面,我们已经做子大量的工作(Ｍｏｌｌ,1987)。啤酒中的…     

啤酒中的混浊活性蛋白质

1前言啤酒的成分复杂,稳定性不强,易产生混浊沉淀。最常见的啤酒非生物混浊是蛋白质混浊。形成蛋白质混浊的原因在于啤酒中有两种主要成分,即蛋白质和多酚物质。在啤酒中,某些多酚物质("混浊活性多酚")可以与蛋白质("混浊活性蛋白")结合形成复杂的复合物,且二者存在一定     

饮料中蛋白质——多酚的作用机制

蛋白质－多酚的相互作用是引起饮料混浊的重要原因之一。蛋白质具有混浊形成活性主要取决于它的脯氨酸含量，多酚形成混浊的能力与其分子结构有关，蛋白质与多酚的比例强烈影响到饮料中混浊的形成量。文中叙述了饮料中蛋白质－多酚的作用机制和最新进展。     

标准曲线法测混浊活性蛋白初探

多酚蛋白复合引起的混浊现象是啤酒,果汁需要着重解决的问题之一。本文探讨了标准曲线法测定啤酒,果汁中混浊活性蛋白的可行性。结果表明,PVP的浓度在0.000～0.100g/L范围时,反应产物的浑浊度与PVP浓度成良好的线性关系。     

多酚和蛋白质对苹果浓缩汁二次混浊的影响

采用18000r/min冷冻(-4℃)离心20min的方法处理经二次混浊处理了3个批次的果汁,测定上清液的相应指标,与未处理的果汁做空白对比,由相应的成分的变化,确定混浊物的成分。结果表明:和二次混浊有关的多酚主要是原花青定的聚合体;表儿茶素、儿茶素小分子的酚类不直接参与二次混浊,却是形成二次混浊的前体物质;和二次混浊有关的蛋白质疏水性氨基酸含量高,其中脯氨酸含量大。     

啤酒多酚-蛋白质沉淀及低温酒精冷混浊预测啤酒保质期

啤酒的混浊问题比较复杂，但通常是由多酚—蛋白的复合物引起的非生物混浊；低温酒精冷混浊试验可以快速地预测啤酒保质期，该法简捷，测定结果预见性强，填补国内无快速预测啤酒保质期的技术空白。     

苹果汁中与混浊有关的活性蛋白质的分离纯化

采用疏水作用色谱PhenylSepharoseCL-4B和固相萃取C18柱分离纯化了浓缩苹果汁和鲜榨苹果汁中与混浊有关的活性蛋白质。经过SDS-PAGE,结果表明浓缩苹果汁和鲜榨苹果汁中的活性蛋白质为同一类蛋白,均为疏水性蛋白质,其分子量为36kDa。     

苹果汁中与混浊有关的活性蛋白质的分离纯化

采用疏水作用色谱PhenylSepharoseCL-4B和固相萃取C18柱分离纯化了浓缩苹果汁和鲜榨苹果汁中与混浊有关的活性蛋白质。经过SDS-PAGE,结果表明浓缩苹果汁和鲜榨苹果汁中的活性蛋白质为同一类蛋白,均为疏水性蛋白质,其分子量为36kDa。      

植物多酚-蛋白质复合抗菌膜研究进展

植物多酚作为一种天然抗菌剂,因具有良好的抗氧化和抗菌活性,在抗菌膜材料领域倍受关注。针对植物多酚-蛋白复合抗菌膜的研究现状,该文综述了蛋白抗菌膜的制备原理、性能和应用,重点阐述植物多酚对蛋白膜抗菌性、抗氧化性、机械性能、阻隔性能、微观结构等理化性质的影响,并对植物多酚-蛋白抗菌膜的发展前景进行了展望,以期为深入挖掘植物多酚-蛋白抗菌膜应用范围提供参考。     

酚类物质和硅胶对啤酒中敏感蛋白的吸附选择性研究

啤酒中的混浊活性蛋白（敏感蛋白）富含脯氨酸。对0℃、37℃以及室温下分离的啤酒混浊物质进行氨基酸分析后发现，不同贮藏温度条件下产生的混浊物质中脯氨酸含量差异很大，依次为13．22％，11．30％和10．44％（均为摩尔百分含量），原因是不同贮藏温度下啤酒中的多酚物质氧化聚合情况不同，造成其对敏感蛋白的选择性差异；0℃贮藏条件下，多酚物质对敏感蛋白选择性最高，37℃次之，室温保藏最差：对硅胶吸附的蛋白质进行氨基酸分析后发现，硅胶吸附蛋白质的脯氨酸含量比啤酒总蛋白所含脯氨酸要高出许多，说明硅胶对敏感蛋白有一定的选择性吸附，且不同硅胶产品对敏感蛋白的吸附选择性也有差异，可以把硅胶吸附蛋白质的脯氨酸含量作为评价硅胶产品质量的一个参考性指标。     

Protein haze in bottled white wines: How well do stability tests and bentonite fining trials predict haze formation during storage and transport?

Based on work undertaken over 30 years ago, most Australian winemakers use a heat test (80^oC for six hours) to check white wines for protein stability. Some winemakers consider that this test is too severe, resulting in wines being over-fined with bentonite. This paper presents the results of a study comparing the predictive ability of this test, assessed either by eye, by nephelometry or by optical density, with that of two alternative assays (80^oC for 2 hours and the Bentotest), through the use of storage trials of 8 wines designed to mimic commercial conditions of transport and storage of wine. One of the 8 unfined wines failed to develop haze even under the more severe storage conditions of this study (35^oC for a month or fluctuating between 20^oC and 35^oC for 8 days) and only 6 of the 8 unfined wines developed haze under 'best practice' storage conditions (13^oC–17^oC for 16 months). All the wines fined with bentonite at dosage rates determined by the three predictive tests used in the main part of this work remained bright in bottle after storage trials at 13^oC–17^oC for 16 months, 35^oC for 1 month or fluctuating between 20^oC and 35^oC for 8 days. Therefore the least severe stability test, heating at 80^oC for 2 hours, which generally indicated lower dosage rates in this study, accurately predicted short to medium term stability for these wines under these storage conditions.     

Characterisation of protein-polyphenol interactions in beer during forced aging

Proteins and proteinaceous material were extracted by acetone precipitation of beer that had undergone forced aging through 0 (control), 5 (medium) or 10 (high) heat/chill cycles (60°C 48h/0°C 24h). Size exclusion chromatography analysis of the crude beer extract showed that forced ageing led to a significant increase in binding of phenolic compounds to Protein Z and especially to lipid transfer protein 1 (LTP1). Protein-polyphenol conjugates were also present in high molecular weight (> 100 kDa) and low molecular weight fractions (< 5 kDa), but these conjugates were already present in the fresh beer and were not affected by the forced aging. Treatment of the crude beer extract with sulphite (2 M) dissociated the protein-polyphenol bindings in LTP1 and Protein Z that had been generated during medium forced aging. Identification and quantification of the free, the non-covalently, and the covalently bound phenolic compounds were performed by UHPLC after extraction by methanol, acetic acid, and sulphite, respectively. The amounts of vanillic acid and caffeic acid decreased in the free polyphenol fraction, indicating binding to proteins during forced aging. Epicatechin and quercetin-3-O-glucoside were found to be non-covalently bound during forced aging. Finally, gallic acid, epicatechin, protocatechuic acid, and astragalin were found to be covalently bound already in the fresh beer. © 2020 The Institute of Brewing & Distilling     

澄清剂对黄酒混浊蛋白去除效果的研究

研究了单宁、硅胶和Polyclar R Brewbrite等澄清剂对黄酒混浊蛋白特异性去除的效果,并通过采用N-三（羟甲基）甘氨酸-十二烷基磺酸钠-聚丙烯酰胺凝胶电泳、基质辅助激光解析电离飞行时间串联质谱,研究了黄酒混浊蛋白及不同澄清剂吸附蛋白的分子量、蛋白质种类及来源,并比较了澄清剂处理前后酒样隆丁区分和非生物稳定性的变化。结果表明:黄酒混浊蛋白的主要成分为类燕麦蛋白和二聚α-淀粉酶抑制剂,主要来源于小麦,几种澄清剂对二聚α-淀粉酶抑制剂都有一定的吸附作用,且处理后的酒样稳定性得到提高,其中以单宁效果最为明显。      

用浊度法预测香蕉汁中混浊活性蛋白质和多酚

本研究采用浊度仪测香蕉汁混浊活性(HA)蛋白和多酚含量。为减少内源性蛋白和多酚的影响,分别用聚乙烯吡咯烷酮(polyvinyl polypyrrolidone, PVPP)和膨润土吸附多酚和蛋白质。将单宁酸加入PVPP处理与未处理香蕉汁中,果汁浊度变化与蛋白质含量呈线性相关,在蛋白质含量相同情况下,PVPP处理果汁的浊度较未处理样品小。热处理添加适量明胶的香蕉汁可反映果汁中HA多酚的含量,膨润土处理与未处理系列样品的浊度与其HA多酚含量呈线性相关。浊度法可用于测定香蕉汁中HA蛋白和HA多酚。     

Effects of fining agents on trans-resveratrol concentration in wine

Resveratrol has been identified as a wine component related to moderate wine consumption and a reduction in serum cholesterol levels. Processes such as wine fining that result in loss of resveratrol during winemaking are therefore of interest, and led to these present studies. A number of agents were compared and were found to lower resveratrol levels in all wines to some extent. Results from two studies (1996 and 1997) are reported. The standard addition method was used in combination with High Pressure Liquid Chromatography to calculate resveratrol levels. In Study 1 (1996), recommended maximum levels of all fining agents (Level 3), bentonite, egg white, gelatin + kieselsol and polyvinylpolypyrrolidone (PVPP), lowered resveratrol levels significantly compared to controls (Level 0). Nevertheless, addition of fining agents at Level 0 resulted in resveratrol levels that were significantly higher than those at Level 3, but resveratrol levels in wine from Level 0 were not significantly different from Level 1. In Study 2 (1997), carbon + egg white, and gelatin + kieselsol fining was studied, and their effects differed according to grape variety. Least removal of resveratrol by carbon fining occurred in wine from Cabernet Sauvignon (Vitis vinifera) whereas most removal occurred in wines from Cynthiana (Vitis aestivalis) and Noble (Vitis rotundifolia). Resveratrol levels of control wine were significantly higher than resveratrol levels of wine treated with recommended maximum addition of fining agent in all varieties. Taken overall, any addition of any fining agent lowered resveratrol levels in all wines to some extent, but complex interactions between fining agent and wine variety resulted in different regression trends. While recognising the constraints set by our particular data that could reflect unique circumstances, we are nevertheless able to infer from these trends that low levels of fining agents can be used without statistically significant loss of resveratrol.     

多酚与蛋白质相互作用研究方法进展

多酚因其独特的化学结构而具有抗氧化、抗肿瘤、抑菌等多种生理功效,在食药领域得到广泛应用。多酚与蛋白相结合形成复合物,改变了两者的营养特性与功能结构,利用不同的实验方法和技术可以获得两者之间的结合常数、结合部位、作用力类型、结合位点数、多酚与蛋白结合后引起蛋白构象与生理功能变化以及外界条件对多酚-蛋白结合的影响等信息。本文主要综述了多酚与蛋白质相互作用研究方法进展,包括分子对接技术、紫外-可见吸收光谱法、荧光光谱法、圆二色谱法、傅里叶变换红外光谱法、等温滴定量热法、拉曼光谱法和核磁共振波谱法。综述发现每种方法都有一定的优势与局限性,使用多种方法结合分析可以更加全面的了解多酚与蛋白质的相互作用关系。     

Binding of olive oil phenolics to food proteins

In this paper we investigate the interaction of phenolics extracted from olive oil with different food proteins (sodium caseinate, bovine serum albumin, β‐lactoglobulin and gelatin). Binding parameters are estimated using different experimental techniques: gel filtration, HPLC, isothermal titration calorimetry and NMR diffusion measurements. For comparison, the binding properties of gallic acid and tannic acid are also studied. The affinity of olive oil phenolics for the different food proteins is found to be relatively weak (compared with tannic acid). Binding constants are measured for the different phenolics in the extract: tyrosol and hydroxytyrosol do not (or very weakly) bind to the proteins, whereas other phenolics in the extract had binding constants of the order 10²–10⁴ M ^?1. The binding parameters determined have been discussed in relation to the possible effect of proteins on sensory properties (bitterness) of food emulsions containing olive oil. Copyright © 2004 Society of Chemical Industry     

复合保健茶饮料的工艺研究

以茶叶及几种药食两用植物为原料研制了一种复合保健茶饮料,实验采用脱酚工艺及添加抗坏血酸,解决了饮料混浊沉淀及褐变问题。