生产工艺对高辅料啤酒非生物稳定性的影响

探索了糖化方法、糖化温度、麦汁煮沸时间、麦汁pH值和PVPP添加量等生产工艺对高辅料啤酒非生物稳定性的影响.结果表明:最佳的糖化工艺条件是:采用一次煮出糖化法,糖化温度70℃,麦汁pH值为5.2～5.4,麦汁煮沸90min～100min.在啤酒中添加150mg/L的PVPP,可以明显降低啤酒中的多酚物质,提高高辅料啤酒的非生物稳定性.     

中性蛋白酶对啤酒酿造中麦汁质量的影响

随着啤酒工业的发展,酶制剂在啤酒酿造中的应用越来越广泛.文中主要对中性蛋白酶在糖化过程的应用及对麦汁的影响进行了研究.研究表明,中性蛋白酶添加量在250mg/(kg麦芽)以下,可以使麦汁中α-氨基酸态氮含量提高25%以上,高于250mg/(kg麦芽)反而不利于酶的作用.添加中性蛋白酶只能在一定程度上降低麦汁浊度和敏感蛋白含量,若要进一步提高麦汁稳定性,需要同时采取相应措施,控制麦汁中多酚物质的含量.     

酶制剂及PVPP等添加剂在啤酒生产中的应用

选用绿色食品稳定剂来降低麦汁中的多酚含量。采用均匀设计法对啤酒发酵过程中绿色食品稳定剂的添加量进行优化。选取α-淀粉酶、糖化复合酶、木聚糖酶、单宁、硅胶、麦汁澄清剂和PVPP作为参试因子，按照均匀设计U12（12^10）的方案进行试验，以色度为目标函数（y）对数据进行二次回归分析，得出最优组合为：单宁59．269mg／kg，PVPP357．384mg／kg，硅胶237．214mg／kg，麦汁澄清剂78．991mg／kg，α-淀粉酶1．100mL／kg，糖化复合酶3．300mL／kg，木聚糖酶0．550mL／kg。该优化工艺发酵的啤酒多酚值为101．78mg／L；总氮、色度、pH、总酸、酒精度、双乙酰、CO2与所测的珠江啤酒的指标接近。     

卡拉胶在啤酒生产中的应用

引起啤酒非生物混浊的成分包括：蛋白质、多酚物质、无机盐、碳水化合物以及某些金属离子等。卡拉胶是啤酒酿造过程中比较理想的澄清剂。在麦汁煮沸结束前10min添加卡拉胶．能改善麦汁外观质量；加快麦汁过滤速度；吨酒耗硅藻土量可节省20％左右；水耗、电耗下降5％左右。酿制出的啤酒各项理化指标均符合国家或企业标准。     

荔枝啤酒发酵特性及工艺参数优化

为了优化荔枝水果啤酒酿造工艺,采用单因素试验设计,考察了原麦汁浓度、荔枝果浆添加量和啤酒花添加量对荔枝啤酒的发酵特性和感官指标的影响;基于单因素试验结果,以感官评价分数为响应指标,采用Box-Behnken试验设计和响应面分析对工艺参数进行优化。结果表明,原麦汁浓度、荔枝果浆添加量对荔枝啤酒的发酵度、酒精度、泡持性和苦度影响显著（p<0.05）;啤酒花添加量对荔枝啤酒的泡持性和苦度影响显著（p<0.05）;优化参数条件范围为原麦汁浓度9~11 oP,荔枝果浆11%（V/V）~15%（V/V）,啤酒花0.39~0.44 g/L,预测荔枝啤酒的感官分数在78.00分以上。选择原麦汁浓度10 oP,荔枝果浆15%（V/V）,啤酒花0.40 g/L的条件进行验证实验,感官评价平均分数为78.10分,与预测值相符。在啤酒酿造工艺中添加荔枝,可以丰富水果啤酒品类,赋予其荔枝的特征风味。     

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。     

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。     

国产高α-酸含量酒花的品质研究

以青岛大花作为对照,研究了高α-酸含量酒花品种马可波罗（Marco Polo）和哥伦布（Columbus）的品质和酿造特点,评价高α-酸含量酒花对青岛大花的替代性。结果表明:马可波罗和哥伦布酒花的α-酸含量高,可降低酒花添加量。合葎草酮含量低,苦感柔和。酒花油组分中里那醇和香叶醇含量高,对啤酒的香气贡献大。总多酚及黄腐酚含量较高,但单位α-酸添加的多酚量不足且抗氧化能力略差,可能对啤酒的非生物稳定性、抗氧化性产生影响。从酿造麦汁指标来看,高α-酸含量酒花的使用可达到预期的苦味质,且异构化率高于青岛大花。采用高α-酸含量酒花配合多酚颗粒酒花使用可以改善麦汁的非生物稳定性和抗氧化能力。      

SAZZ多酚颗粒酒花抗氧化性的研究

在麦汁煮沸阶段添加SAZZ多酚颗粒酒花可以使成品在一定的消费周期内具有更好的抗氧化能力,提高啤酒的风味稳定性。     

甲醛对啤酒风味危害的研究

对成品啤酒中的甲醛残留量的测定发现,不同品牌啤酒有不同程度残留甲醛,国产啤酒含量相对较高。在实验室中,通过啤酒酿造实验发现,随着糖化时甲醛添加量的增加,麦汁及啤酒中甲醛践留量也逐步增加,对啤酒风味稳定性损害也越大。同时又研究了酿造单宁、复合硅胶、PVPP 替代甲醛使用的可行性,发现三者均可提高啤酒非生物稳定性,并可延长啤酒风味保鲜期。     

PV PP对枸杞果酒多酚物质及品质的影响

研究聚乙烯吡咯烷酮(PVPP)对枸杞发酵果酒多酚物质的吸附作用及酒体口感的影响,采用PVPP对酒体进行处理,研究发现,PVPP对酒体中多酚类物质有显著的吸附作用;PVPP对枸杞发酵果酒品质的实验结果表明,1500 mg/L的PVPP处理酒体,使得酒体苦味适中,口感醇厚,酒体褐变防止率达到23.78%,并且PVPP对酒体中蛋白质的吸附作用显著,对酒精度、糖度等指标影响不显著。     

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。     

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.     

Optimising Beer Stabilisation by the Selective Removal of Tannoids and Sensitive Proteins

Colloidal stabilisation of all malt and adjunct lager beers through selective removal of haze sensitive glycoproteins using silica gel and tannoid polyphenols using polyvinylpolypyrrolidone (PVPP) or a polyvinylpyrrolidone (PVP)‐modified silica gel has been demonstrated during full brewery production. At this scale PVPP and the PVP‐modified silica gel exhibited equivalent binding capability for tannoid polyphenols although PVPP removed additional polyphenolic species. Characterisation of proanthocyanidins following treatment at 4°C with PVPP and the PVP‐modified silica gel silica co‐product confirmed that PVPP removes a wider range of polyphenolics. Both products exhibited poorer polyphenolic binding capability at 4°C as would be expected for a physical adsorption process.     

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。     

介绍一种快速测定敏感多酚的新方法

国外开发出单分析仪，用PVPP滴加法测定啤酒浑浊敏感多酚，该法快速、准确。单宁仪可动态反映出啤酒酿造过程中敏感蛋白和敏感多酚的变化趋势。（丹妮）     

Adsorption of Cu2+ by Crosslinked Graft Copolymers of Starch

With the use of acrylic acid(AA)as a monomer,humic acid(HA)and starch as raw materials,potassium persulfate(KPS)as initiator,and N,Ndimethylacrylamide(MBA)as a cross-linking agent,AA/HA/Starch graft copolymer was prepared and characterized by SEM and FT-IR.The effects of temperature,adsorption time,adsorbent dosage,pH value and Cu²⁺initial concentration of the solution on the adsorption performance of the crosslinked graft copolymer were also investigated.The results showed that the Cu²⁺adsorption capacity of the AA/HA/Starch graft copolymer increased firstly and then decreased with increasing adsorbent dosage and the initial pH value of Cu²⁺solution.With the increase of Cu²⁺initial concentration and the extension of adsorption time,the adsorption amount of Cu²⁺increased rapidly and then stabilized.And it decreased slightly with the increase of temperature.At pH value of 5.5,temperature of 298 K,adsorbent dosage of 50 mg,adsorption time of 125 min,and 100 mL Cu²⁺solution with Cu²⁺initial concentration of 100 mg/L,the Cu²⁺adsorption capacity of the crosslinked graft copolymer was 238 mg/g.The adsorption of Cu²⁺by the adsorbent followed the pseudo-second-order kinetic equation and Langmuir isothermal adsorption model,and the adsorption was attached to monolayer chemical adsorption.This study proved that AA/HA/Starch graft copolymer could be used as an efficient adsorbent for the removal of harmful and toxic metal cations such as Cu²⁺from industrial wastewater.     

刺梨多酚的纯化工艺及体外抗氧化研究

以刺梨全果为原料,探讨刺梨多酚的纯化工艺,并分析其抗氧化作用。比较AB-8、D101、D301、HPD100、HPD300和LSA-10六种不同型号的大孔树脂对刺梨多酚的吸附及解吸效果,筛选最佳大孔吸附树脂;在三个实验温度下探讨AB-8型对刺梨多酚的静态吸附热力学特性,通过研究初始pH、吸附时间、解吸液浓度、上样量及洗脱液用量等多个因素优化刺梨多酚的纯化参数,并进一步研究其抗氧化活性。结果表明,AB-8型大孔树脂更适于刺梨多酚的吸附,其吸附过程符合Freundlich热力学模型(R²>0.990 0)及Langmuir模型(R²>0.950 0),当实验温度为298 K时更利于大孔树脂对刺梨多酚的吸附;其较适纯化参数为：吸附时间600 min、解吸溶剂80%乙醇溶液、上样量10 mL、洗脱液用量50 mL。在该纯化工艺参数下,刺梨多酚的平均含量从30.45%增加至56.92%。抗氧化实验表明,刺梨多酚有较好的抗氧化能力,粗提液和纯化液对DPPH·及ABTS⁺·的清除能力都存在显著差异,在同一浓度下纯化后的刺梨...