THE USE OF 14C-LABELLED POLYPHENOLS TO STUDY HAZE FORMATION IN BEER

Haze formation in beer is claimed to involve the gradual polymerization of polyphenols and their subsequent reaction with proteins to form insoluble complexes. The mechanism of haze formation has now been studied using ¹⁴C-labelled epicatechin and dimeric catechin. Epicatechin does not polymerize to form dimeric or trimeric polyphenols when beer is stored and is only incorporated into beer haze to a small extent. Some of the epicatechin combines with nitrogen-containing compounds during storage to form soluble complexes. However, dimeric catechin does not form soluble complexes with nitrogen-containing compounds and instead there is a substantial incorporation of this dimer into beer haze. Dimeric polyphenols are important haze precursors which form insoluble complexes with one or more of the polypeptides of beer, probably by an oxidative coupling mechanism.     

咨询活动效益综合评价模型研究

建立了综合评价指标体系；运用直接和间接量化方法，对难以客观评价的在社会上产生的经济效益和社会效益进行了量化；使用层次分析法，确定了各指标和各分指标的权重；采用区间值抽样调查方法，给出了各指标和各分指标的参考值；利用Ｆｕｚｙ综合评判思想，对评价总得分的计算和咨询机构的定级给出一种较理想的方法．     

EFFECT OF VARIOUS POLYPHENOLS ON THE RATE OF HAZE FORMATION IN BEER

The effect of the addition of a range of monomeric, dimeric and polymeric polyphenols to beer on the rate of haze formation has been examined. Monomeric polyphenols had no significant effect on haze formation. The addition to beer of dimeric or polymeric polyphenols caused a large increase in the rate of haze formation.     

FORMATION OF N-NITROSAMINES IN LOW MOISTURE SYSTEMS

Experiments have shown that N-nitrosamines can be formed when sodium nitrite and dialkylamines are heated in low-moisture model systems. Parameters which may influence the reaction were investigated. Results revealed that maximum N-nitrosamine formation depended on temperature and time of heating, sodium nitrite-amine ratio and pH of the system.     

ELECTROFOCUSING STUDIES ON THE FORMATION OF BEER HAZE

The composition of protein fractions obtained from beers stored under differing conditions has been studied using a modified system for isoelectric focusing in thin layers of polyacrylamide gel which permitted the numerical evaluation of the focused bands by a scanning densitometer. The incorporation of concentrated urea in the gel enabled beer hazes to be assessed in this manner. The ageing of an unstabilized all-malt beer resulted in an increase in the proportion of acidic material (pl <5.0) although no new protein bands were formed. The derived hazes were enriched with acidic components but contained all except the most basic fractions present in the beer.     

葡萄酒酒石形成机理及其防止

对葡萄酒中酒石的形成机理和影响酒石形成的因素进行了分析和探讨,并提出了解决葡萄酒酒石稳定性的措施.选择合理的添加剂将是解决葡萄酒酒石稳定性的经济、有效的途径.     

STABILITY OF CURCUMINOIB PIGMENTS IN MODEL SYSTEMS

The influence of water activity on the stability of curcuminoid pigments in curcumin- and turmeric oleoresin- microcrystalline cellulose model systems during storage at 21 ± 1C was investigated. The water adsorption characteristic of the model systems was determined. The samples were stored under nitrogen/darkness, nitrogen/light, air/darkness and air/light at water activities of 0.33, 0.57 and 0.97. At specific time intervals, samples were analyzed spectrophotometrically for curcuminoid pigments content. The degradation of curcuminoids in every condition tested followed a first order reaction. Curcuminoid pigments were observed to be sensitive to light, however the combined effects of air and light were the most deleterious. There was no influence of water activity on the stability of curcuminoid pigments in curcumin- and turmeric oleoresin-microcrystalline cellulose model systems.     

黑米清酒生产工艺的研究

以黑米、大米为原料,采用液态发酵法,通过正交实验,确定黑米清酒的最佳发酵条件,发酵液初始pH值为5.0:酒母添加量为5%;米曲添加量为0.2%.获得16°、口味协调、玫瑰红色的黑米清酒,并对黑米清酒的理化指标、感官指标进行了分析.     

STABILITY OF CAROTENOIDS IN MODEL AQUEOUS SYSTEMS1

The stability of the carotenoids, beta-carotene, apo-8′-carotenal and canthaxanthin, was studied in the model systems of cellulose and starch equilibrated under different relative humidities. Water perse was found to exert a protective influence on these carotenoids and this effect was evident below and above the monolayer coverage for the two systems. The extent of protection increased with the moisture content and was also modified by the nature of the system and the type of carotenoid pigments. In general, canthaxanthin was the most stable and betacarotene was the least stable. The protective effect of water is probably due to the formation of hydrogen bonds between water and hydroperoxide molecules and the resultant extension of the monomolecular rate period.     

THE REACTIONS BETWEEN POLYPHENOLS AND ALDEHYDES AND THE INFLUENCE OF ACETALDEHYDE ON HAZE FORMATION IN BEER

The reactions and interactions between proteins and polyphenols are, among other phenomena, responsible for haze formation in beer. The participation of aldehydes in the polymerisation of polyphenols is considered. The formation of phenolic Baeyer-type condensation products containing phenolic residues linked by CH₃CH-bridges through reaction with acetaldehyde is possible at the pH of beer (4.0). These and other reactions with acetaldehyde in beer participate in beer haze formation.     

模糊排序在酿酒葡萄梅鹿辄上的应用

本文运用模糊数学中的模糊排序方法，对酿制干红葡萄酒品种梅鹿辄进行种植区域的研究，通过对新疆部分地区相似因子的综合排序，结果发现焉者，伊犁等地是合适的地区，哈密为不适宜地区。     

THE INTRINSIC INFLUENCE OF CATECHINS AND PROCYANIDINS ON BEER HAZE FORMATION

Different concentrations of catechins and procyanidins were added to an all-malt Pilsner beer brewed from proanthocyanidin-free malt (ant 13·13 × Rupal) and tannin-free hop extract in order to evaluate their intrinsic role in beer haze formation, i.e. in the absence of malt and/or hop flavanoids. The molar tanning capacities of flavanoids depend upon their degree of polymerisation. Procyanidin B6 was much more haze active than procyanidin B3. Both immediate haze and formation of haze after 150 days of storage at room temperature was in general linearily related to the added concentration of phenolics.     

PHENOLIC CONSTITUENTS OF BEER AND BREWING MATERIALS. II. THE ROLE OF POLYPHENOLS IN THE FORMATION OF NON-BIOLOGICAL HAZE

Simple and polymeric polyphenols differ in the way in which they influence the development of chill and permanent hazes in bottled beer. The addition of simple anthocyanogens to beer causes a marked increase in the rate of haze formation whereas added polymeric materials induce immediate and intense turbidities. Beer anthocyanogens constitute a class of materials ranging in complexity from simple compounds to heterogeneous polymers which sometimes include polyphenolic units that are incapable of yielding anthocyanidins with acid. The extent to which the various anthocyanogens present in beer are involved in haze formation is not reflected by their contributions to the overall anthocyanogen value of the beer. Haze-inducing polymers which contain no anthocyanogen residues may also be present in beer. The nature and origin of polyphenolic substances in beer and the methods by which they may polymerize to give immediate haze precursors are discussed.