一次性与再生性PVPP应用于啤酒生产的比较

PVPP能高效吸附导致啤酒浑浊的聚合多酚，解决啤酒中的非生物浑浊问题。PVPP有一次性和再生性两种规格，文中通过实验探讨了一次性和再生性PVPP分别使用中对多酚及蛋白质吸附的比较。     

PVPP对啤酒中多酚类物质和蛋白质的吸附作用比较

为了比较PVPP对啤酒中多酚类物质和蛋白质的吸附作用,以牛血清蛋白为例,采用PVPP分别处理原啤酒、牛血清蛋白(BSA)溶液以及BSA原啤酒混合溶液。实验发现,在相同条件下,尽管PVPP对牛血清蛋白具有较强的吸附作用,但对啤酒中多酚类物质的吸附作用更强;而在BSA原啤酒混合溶液中,多酚类物质被吸附量远远大于牛血清蛋白。结果表明,多酚类物质通过竞争吸附占据PVPP的吸附活性点。     

应用新技术提高啤酒的胶体稳定性

引起啤酒胶体非稳定性混浊的主要物质为蛋白质和多酚物质。可采取在麦汁煮沸阶段加入胶体物质和在贮酒过程中加入硅胶，使啤酒中的高分子蛋白质沉淀而过滤除去。利用PVPP作为多酚吸附剂对啤酒进行二级过滤，可降低啤酒中的多酚物质，也可将PVPP同硅藻土、硅胶联用过滤，降低啤酒的多酚物质。     

国产PVPP的性质及对啤酒质量影响的初步研究

对国产一次性及再生型PVPP性质进行了初步研究，与进口产品相比，发现国产PVPP中除一次性PVPP膨胀性较低以外，其它指标相差无几，而再生型PVPP没有明显区别。添加国产一次性PVPP100mg／L-200mg／L时，有利于提高啤酒的非生物稳定性及风味稳定性；在相同的使用次数下，国产再生型PVPP对总多酚的吸附能力略低于进口产品，但损失率略高。     

PVPP吸附啤酒中多酚类物质的研究

采用自制PVPP吸附啤酒中的多酚类物质。通过实验发现 :PVPP的交联度为0 5 % ,用量为 0 3g/L啤酒时 ,啤酒中多酚类物质的残留率为 1 8 2 5 % ,回收再生PVPP的吸附能力为新PVPP吸附能力的 98 5 3%。     

浊度法测定改性MTS与甲醛对多酚作用效果的比较

本实验尝试采用TURB-2A精密浊度仪代替单宁分析仪用PVPP滴定击对改性MTS及甲醛对啤酒中多酚的作用效果进行比较，获得一定可参考结果。     

提高啤酒稳定性的研究——PVPP专题

PVPP(聚乙烯吡咯烷酮)对于啤酒稳定的作用已在啤酒工业的广泛采用中得到肯定。PVPP 可以选择性的吸附导致冷浑浊与永久性浑浊的多酚,而对啤酒没有不利的影响。这使啤酒酿造者得以保证啤酒在其声明的货架寿命期内到达消费者手中时保持清亮、诱人的外观。考虑啤酒胶体不稳定性的机理,使用 PVPP 可以有效地实现啤酒稳定。根据酿造者的要求可以使用一次性和再生级的材料。它们的性能与在啤酒厂的使用情况已很明确。为确保有效的稳定性能,PVPP 可以与其它啤酒稳定剂一起使用,如硅胶、单宁和木瓜酶。对用“联合稳定剂”的优点进行研究后引出了一种新颖的 PVPP+硅干凝胶的混合物。它可以同时减少浑浊的前驱物-活性浑浊多酚和蛋白蛋。     

PVPP在啤酒生产上的应用

随着啤酒生产过滤技术的发展,用过 PVPP 过滤啤酒的技术已开始在世界上使用。目前我国的许多啤酒厂也开始用 PVPP 来过滤啤酒。 PVPP 的性质PVPP 即聚乙烯吡咯烷酮,化学分子式(C_6H_9NO)n,为白色吸水性粉末,带有微弱为人可接受的气味。比重1.2,不溶于水及各种常用的有机溶剂,pH 值(1%悬浮液)5～8,在水中及啤酒中体积膨胀2.3～2.5倍,直径在1～450μm之间。PVPP 的吸附能力较高,40克 PVPP=80克硅藻土的吸附能力。     

聚乙烯聚吡咯烷酮吸附多酚物质性质研究及其在无甲醛酿造啤酒工艺中的应用

本文主要研究PVPP(聚乙烯聚吡咯烷酮)吸附多酚的性质,及其在无甲醛酿造工艺中的应用。结果表明,麦汁或啤酒中的敏感蛋白、酒精度、pH以及PVPP的添加量和添加方式等因素对PVPP吸附多酚都有一定影响。当pH在4.0左右,酒精度在3%(V/V)左右时PVPP的吸附效率最高。PVPP在添加量较低的情况下有一定的吸附专一性,主要吸附高分子的聚合多酚,但在添加量较高的情况下,不具备此性质,对单体酚的吸附迅速增加,会降低麦汁或啤酒的抗氧化能力。PVPP结合硅胶使用可以有效替代甲醛在啤酒酿造中的应用,在保证啤酒非生物稳定的条件下,改善啤酒风味稳定性和抗氧化能力。     

麦芽、酒花多酚对啤酒风味、非生物稳定性的影响

利用12°P 下面发酵啤酒的中试实验,分析经过处理的酒花与麦芽多酚对啤酒质量、风味、非生物稳定性的影响。结果证实在麦汁煮沸过程中麦芽多酚,特别是酒花多酚能够提高新鲜啤酒及储藏啤酒的还原力,降低其羰基化合物含量(TBA 值为代表)。如降低麦芽中多酚含量或采用二氧化碳酒花浸膏生产的啤酒,其 TBA 值会增加。而经过 PVPP 稳定化处理后啤酒倾向于稍低的还原力。麦芽与酒花中的多酚影响新鲜啤酒的“粗糙感”程度,而经过 PVPP 稳定性处理后的啤酒没有观察到明显的影响,强制老化啤酒的老化程度取决于糖化中多酚含量。麦芽多酚与酒花中多酚均对啤酒的风味稳定性有积极影响,PVPP 稳定化处理对啤酒的风味稳定性有积极影响。多酚,特别是酒花多酚能够降低9个月储藏啤酒的风味老化程度,主要表现在前4个月。结果同时也证实了麦芽与酒花中的多酚对啤酒非生物稳定性的负面影响,经过 PVPP 稳定化处理后,在采用不同多酚含量原料所酿造的啤酒之间,以及保质期预测值之间的差异会降低到最低。     

使用PVPP提高啤酒稳定性的探讨

PVPP通过酚羟基和羰基之间的氢键结合,进行表面吸附,有效地去除多酚。啤酒经PVPP稳定后达到了胶体的高稳定性,而且口感稳定性更佳。过滤中添加300mg/L,8min、300mg/L,10min、400mg/L,8min的PVPP后,啤酒具有良好的多酚稳定性和较好的蛋白稳定性。     

The Role of Malt and Hop Polyphenols in Beer Quality,Flavour and Haze Stability

Pilot‐scale brewing trials of a 12°P pale lager beer were conducted to look at the effect of a modified dose of hop and malt polyphenols on haze, flavour quality, and stability. Results confirmed that malt polyphenols, and particularly hop polyphenols, in the course of wort boiling, improved reducing activity values and the carbonyl content in fresh and stored beers. Hop polyphenols significantly increased reducing activity and decreased the formation of carbonyls (TBA value) in fresh and stored beer. Reduced content of malt polyphenols, combined with the use of hop CO₂ extract, caused an increase in the TBA value in beer. PVPP stabilized beers tended to be lower in reducing activity. Both malt and hop polyphenols affected the intensity of “harsh taste” in fresh beers and a significant influence from PVPP stabilization of beer was not observed. The staling degree of forced‐aged beers depended on the polyphenol content in the brewhouse. Both hop and malt polyphenols had a positive impact on flavour stability. PVPP treatment of beer had a positive effect on the flavour stability of heat‐aged beers. Polyphenols, especially hop polyphenols, slowed down flavour deterioration during the nine month storage period, but the primary effect was seen during the first four months of storage. Storage trials did not show any unambiguous effects for PVPP stabilization on beer flavour stability. Results confirmed the negative impact of malt and hop polyphenols on haze stability, and PVPP stabilization minimized differences in shelf life prediction values between beers prepared with the modified dose of polyphenols.     

新型添加剂Brewbrite在麦汁制造中的应用

对Brewbrite在麦汁中的应用进行了初步研究．通过麦汁外观和其他指标的分析。结果表明,在麦汁煮沸结束前10min添加Brewbrite 30mg／L,可以有效地澄清麦汁,降低麦汁中的可凝固性氮含量。与卡拉胶、单宁、HD-003,DHG,PVPP等添加剂相比,Brewbrite可降低麦汁和啤酒中的总多酚含量、可凝固性氮含量、麦汁色度、麦汁浊度等,减少高分子氮的比例,有助于提高啤酒的非生物稳定性。（孙悟）     

Identification of the Polyphenols in Barley and Beer by HPLC/MS and HPLC/Electrochemical Detection

Barley polyphenols were isolated using acetone/water (70/30) followed by Sephadex LH-20 chromatography. HPLC/Electrospray mass spectrometry showed the presence of proanthocyanidin dimers, trimers, tetramers, and pentamers. HPLC/electrochemical detection was used to survey the contents of these compounds in a range of barley varieties. Principal components analysis showed that the naked barley varieties Morrell, and to a lesser extent Namoi, were different from the other barley varieties. Beer polyphenol extracts were prepared using Sephadex LH-20 chromatography. A large number of proanthocyanidin dimers and trimers could be detected using HPLC/MS. HPLC/electrochemical detection was used to survey a range of beer types. Compounds detected included catechin, epicatechin, gallocatechin, epigallocatechin, a number of proanthocyanidin dimers and trimers, and a number of phenolic acids. The peaks removed by PVPP have been determined. Principal components analysis was used to identify those compounds which distinguished the beer types. The first principal component was due to prodelphinidin B3, catechin, gallocatechin and two unidentified compounds which were removed by PVPP and the second principal component was due to phenolic acids. Efforts to identify the compounds removed by PVPP have commenced.     

Beer Fluorescence and the Isolation,Characterisation and Silica Adsorption of Haze‐Active Beer Proteins

The fluorescence spectra and lifetimes of diluted beer have been explored and found not to report on protein removal either by silica or tannic acid, nor polyphenol uptake by PVPP. Comparing the fluorescence spectra of beer with that of tea and hops, it seems that proteins, complex polyphenols and iso‐α‐acids can contribute to the intrinsic fluorescence of beer, although the contribution from polyphenols must be minimal since treatment with PVPP does not dramatically change the background fluorescence. To eliminate the problem of background fluorescence haze‐active protein was isolated. Steady‐state and time‐resolved fluorescence techniques were used to characterise these and to monitor their uptake by different silica gels as a function of pH. Heat treated large pore volume, small surface area silicas were the more effective adsorbers for the proteins under study, with pH 4 being optimum. Using both intrinsic amino acid fluorescence and the extrinsic fluorophore fluorescamine, the time‐resolved fluorescence anisotropy has been measured and the radius of the isolated haze protein found to be ～ 35 Å. Comparisons have been made with proteins of known size and structure such as human and bovine serum albumins (HSA and BSA).     

PVPP在乌龙茶饮料中的应用研究

合成了交联聚乙烯吡咯烷酮(PVPP),研究了PVPP对乌龙茶饮料的处理效果与条件。研究表明,PVPP可吸附茶饮料中的部分茶多酚,进而延缓沉淀或浑浊的发生,提出茶饮料的稳定性,延长茶饮料的贮存期。并对PVPP的重复使用性能进行了研究,提出了PVPP可行的再生方法。