PREPARATION OF HOP EXTRACTS WITHOUT USING ORGANIC SOLVENTS

Extraction of hops with liquid carbon dioxide at ambient temperature provides an attractive means of producing hop extracts which are rich in α-acids and free from hard resins, polyphenols, pigments and residual organic solvents. The resulting yellow extracts give beer with a clean bitter flavour when they are added during wort boiling. Manufacturing costs using the process are likely to be substantially less than in a conventional hop extraction plant.     

FATTY ACIDS IN ISOMERIZED HOP EXTRACTS AND GUSHING

A procedure is described for the analysis of fatty acids (C₁₂-C₁₈ individually and C₁₈₊ as a group) in hops, hop extracts and isomerized hop extracts, and analytical results are quoted for twenty-one different samples of hops or hop products. Isomerized extracts varied widely in their content of fatty acids and isomerization and processing of hops appeared to eliminate some fatty acids selectively so that isomerized extracts were enriched in palmitic acid, linoleic acid and linolenic acid. Some hop extracts had a surprisingly high content of lauric acid. The analytical results are discussed in relation to gushing.     

HOP PRODUCTS

Hop products have established an important and permanent position in the brewing raw materials market. Hop pellets and hop extract offer significant advantages to traditional brewers. However, the ultimate hop product is the isomerised hop extract, which can now be produced without the involvement of organic solvents. Still to be resolved and hence controlled is the contribution of the hop oil fraction to beer flavour.     

PILOT PLANT EXTRACTION OF HOPS WITH LIQUID CARBON DIOXIDE AND THE USE OF THESE EXTRACTS IN PILOT AND PRODUCTION SCALE BREWINGa

Several varieties of hop have been satisfactorily extracted using liquid carbon dioxide in a plant operating on the 1 kg scale. The extracts have been used in small scale (0·6 and 16 hl) and production scale (700–800 hl) brewing trials where both ales and lagers were produced. All beers were of sound quality and could not be distinguished organoleptically from controls brewed with either hops or commercial hop extracts.     

RAPID SPECTROPHOTOMETRIC METHOD FOR DETERMINATION OF THE BITTERING VALUE OF ISOMERIZED HOP EXTRACTS

A method is described which allows the rapid determination of the bittering value of isomerized hop extracts. The method is also applicable in the case of isomerized hop extracts containing impurities such as α-acids and β-acids.     

PRODUCTION-SCALE APPARATUS FOR THE INJECTION OF HOP EXTRACTS INTO BEER USING LIQUID CARBON DIOXIDE

Extracts of hops made with liquid carbon dioxide can be substituted for dry hops to introduce the flavour of hop oils into beer. Apparatus has been devised so that such extracts can be redissolved in liquid carbon dioxide and then metered into beer. Successful trials have been carried out on the commercial scale.     

THE STABILITY OF HOP OILS IN LIQUID CARBON DIOXIDE EXTRACTS OF HOPS

Portions of extracts obtained by treating three varieties of hops with liquid carbon dioxide were stored in the cold and at ambient temperature for 18 months. During this period the composition of nop oils remained stable, except for the formation of two terpene methyl sulphides in extracts from all three varieties. Ales were ‘dry-hopped’ using portions of the stored extracts and, despite formation of the two sulphur compounds, the resulting hop character was satisfactory in all cases.     

EFFECTS OF PRODUCTS FROM SEEDLESS AND SEEDED HOPS ON BEER QUALITY

Comparative semi-industrial brewing trials with standard Continental lager beers have been carried out in Switzerland using hop pellets and hop extracts made from seeded and seedless hops. It has been demonstrated that the products from seeded hops containing 8% and 9% of seeds have no adverse effect on beer quality and that the flavour of all the beers was acceptable.     

QUANTITATIVE DETERMINATION OF HOP BITTER SUBSTANCES AND THEIR DERIVATIVES IN HOP EXTRACTS BY THIN LAYER CHROMATOGRAPHY

A method is described which allows the separation of hop bitter components and derivatives present in hop extracts by thin-layer chromatography on a mixture of silica gel and cellulose. This method can be used to evaluate the purity of hop extracts, isomerized hop extracts and complementary base extracts.     

PREPARATION OF OIL RICH HOP EXTRACTS AND THEIR ADDITION TO BEER ON THE PILOT-SCALE USING LIQUID CARBON DIOXIDE*

The introduction of carbon dioxide hop extracts dissolved in liquid carbon dioxide to green beer during transfer from fermentation vessel to cold conditioning tank results in a sound dry hop flavour in the finished product. A system has been developed for injecting a solution of extract into a beer main. Extracts which are rich in hop oils are particularly suitable for imparting hop character to beer and a liquid-liquid countercurrent procedure is described for producing extract fractions containing enhanced levels of essential oil.     

PROTEIN PRECIPITATION DURING WORT BOILING: QUALITY ASPECTS OF DIMINISHED WORT BOILING TIMES OF BREWS PREPARED FROM PROANTHOCYANIDIN-FREE OR REGULAR RAW MATERIALS

When using proanthocyanidin-free materials for the production of beer, a reduction of the wort boiling time can be considered. In worts prepared with regular malt and tannin-free hop extract there is a continuous precipitation of the malt flavanoids while in brews prepared from proanthocyanidin-free malt and regular hops there is a simultaneous extraction and removal of the hop flavanoids leading to constant levels of these hop flavanoids. The results also show that the level of Kjeldahl nitrogen in worts boiled with hops will be the same as that in worts boiled with n-hexane tannin-free hop extracts. These results and the fact that more protein precipitates in brews containing no malt or hop proanthocyanidins suggest that, unlike what is the case during the development of beer haze, polyphenols are not necessary for an effective protein precipitation during wort boiling.     

超临界萃取啤酒花浸膏及其萃余物中多酚化合物提取的研究

CO2啤酒花浸膏因质量稳定,易于储存和利用率高等特点在啤酒酿造中的使用量正在逐年增加。文章考察了超临界CO2萃取啤酒花浸膏的工艺对产品中啤酒花多酚含量的影响,并以超临界CO2萃取啤酒花的萃余物质为原料,研究了从中提取啤酒花多酚的可能性。结果表明,当萃取温度为40℃,萃取压力大于25MPa时,浸膏中的多酚含量明显提高,更高的提取温度得到的产品中多酚的含量没有明显的提高。采用溶剂法从萃余物质中提取啤酒花多酚的实验表明,50%(W/W)的丙酮-水的混合溶剂体系对啤酒花多酚的提取效果最好,总收率可达到83.70%(W/W),从超临界萃取啤酒花的萃余物质中提取啤酒花多酚可提高啤酒花综合利用的价值。     

新型酒花制品在啤酒工业的应用

啤酒花是啤酒工业的重要原料之一。阐述了啤酒花中3类物质即酒花树脂、酒花油、多酚物质的主要化学成分，酒花在啤酒酿造中的作用，以及酒花浸膏和酒花油等多种新型的酒花制品在啤酒工业中的应用。     

HOP RESIN ANALYSIS BY HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY ON MICROPARTICULATE SILICA

A high-performance liquid chromatographic separation of hop resins on a commercially available microparticulate silica has been developed. The chromatography involves a new mechanism in hop resin separation. A solvent containing di-n-butylammonium acetate is used. The method gives good separation of α-acid, iso-α-acid, β-acid and humulinic acid, and has been used for the quantitative analysis of α-acid and iso-α-acid in hop extracts and isomerised hop extracts.     

ADDITION OF HOP EXTRACTS TO BEER USING LIQUID CARBON DIOXIDE*

A method is described for imparting hop character to beer using extract prepared by treating hops with liquid carbon dioxide. The long contact times required for conventional dry-hopping techniques are avoided, and the use of liquid carbon dioxide as a medium for dispersal of the extract obviates problems due to residual organic solvent or emulsion stabilizers. Beers in which hop character was introduced in this way were found to be similar in flavour to control beers treated with portions of the same hop extract dissolved in ethanol.     

啤酒花废弃枝叶多酚、黄酮含量与抗氧化活性的相关性分析

采用不同极性溶剂对新疆种植的札一和马可波罗啤酒花废弃枝叶的乙醇提取物进行不同极性部位的分 离,以羟自由基、1,1-二苯基-2-三硝基苯肼自由基、β-胡萝卜素-亚油酸及磷钼酸4 个不同的抗氧化活性评价体系 对获得的各提取物的抗氧化活性进行比较性研究,并与提取物中多酚、黄酮含量进行相关性分析。结果表明, 乙醇提取物及各极性部位均具有一定的抗氧化性。其中,乙酸乙酯提取物中的多酚和黄酮的含量均最高,其在主 枝、侧枝和叶子的含量范围分别为5.80～34.20 mg/g和2.00～18.00 mg/g;水相中最低,上述各物质的含量范围仅为 0.73～11.05 mg/g和0.06～5.74 mg/g。相关性分析表明,啤酒花主枝、侧枝和叶子抗氧化活性与其多酚、黄酮含量 具有显著的相关关系（P＜0.05）。     

The phenolic content and antioxidant activity of the aqueous and hydroalcoholic extracts of hops and their pellets

The goal of this study was to investigate how three commonly used systems (water, 50% methanol and 50% ethanol) affected the yields of phenolic substances and the antioxidant capacity of extracts prepared from hops (cv Magnum and Marynka) and their pellets (T90 and T45). The total phenolic (TPC) and total flavonoid contents (TFC), as well as antioxidant activity (ABTS^+? scavenging, reducing power and metal chelating activity) of the hydroalcoholic extracts were found to be significantly higher than those of aqueous extracts. Extraction using 50% ethanol produced the highest yield of flavonoids. In turn, aqueous–methanol extracts were a better source of chlorogenic acid. No significant differences in terms of TPC and TFC were found between extracts prepared from hops and their pellets when water was used for extraction. Aqueous–ethanol extracts of T45 pellets, regardless of the hop variety, exhibited higher TFC compared with those of T90 pellets. For aqueous and aqueous–methanol extracts, such a tendency was not observed. Extraction with water revealed that cv Marynka hops and pellets had higher TPC than those of cv Magnum, which resulted in their better antioxidant potential. Hydroalcoholic extracts, regardless of the type of alcohol and hop product, did not differ significantly in terms of antioxidant activities. Copyright © 2013 The Institute of Brewing & Distilling     

Antioxidant Characteristics of Hops and Hop Products

The method based on the reaction of stable DPPH radical proved to be the best for the determination of antioxidant characteristics of hops and hop products. Antioxidant activity is expressed as the rate of decline in absorbance of the reaction environment and assessed in relative percents. Differences in the values of antioxidant activity were determined in Czech and foreign hop varieties. The highest antioxidant activities in the scope of 70 to 80% rel. were measured in Saaz and Spalter Select. Antioxidant activity in most of the varieties moved in the scope of 40 to 60% rel. A part of antioxidant activity of hops is irreversibly lost in the course of drying. The loss does not usually exceed 5% of the original RA_DPPH value. Drying also resulted in a decrease of polyphenol compound contents. Drying in belt and chamber kilns is comparable from the point of view of preserving hop antioxidant properties. Results of determination of antioxidant activity in hot water extracts of raw hops and ground hops were comparable and statistically non‐significant. The same held true for pelletizing of ground hops. The antioxidant activity of raw hops declined in the course of long‐term storage in dependence on storage temperature. Storage temperature had no effect on the antioxidant activity of the hop pellets packed in a multi‐layer foil without air access.     

啤酒花苦味酸对血糖调节作用的研究

观察啤酒花超临界CO2 浸膏、β- 酸和六氢β- 酸对糖尿病小鼠血糖的调节作用。对四氧嘧啶复制的糖尿病小鼠的动物模型进行为期1w 的啤酒花超临界CO2 浸膏、β- 酸和六氢β- 酸的高、低剂量(30、15mg/kg)组和阳性药物格列本脲片灌胃治疗,观察小鼠的糖尿病“三多一少”的症状和治疗前后血糖和糖耐量的变化。与模型对照组相比,治疗组糖尿病小鼠的“三多一少”症状得到明显地改善,治疗前后血糖和糖耐量的变化结果表明,超临界CO2 浸膏和β- 酸的高剂量组治疗后的血糖值与正常组(p ＞ 0.05)无明显差异。对治疗后小鼠的血糖值采用单一自由度正交比较的方差分析表明,正常组小鼠的血糖值与模型组有极显著的差异,模型对照组与治疗组之间也具有非常显著的差异(p ＜ 0.01);在各治疗组之间,灌胃优降糖片的小鼠的治疗效果与灌胃不同剂量的β- 酸、六氢β- 酸和超临界CO2 浸膏样品的小鼠的总体治疗效果相当(p ＞ 0.05)。啤酒花超临界CO2 浸膏、β- 酸和六氢β- 酸对小鼠糖尿病症状均有一定的治疗作用,该作用与灌胃样品的剂量呈正相关关系。     

酒花制品中异α-酸浓度的测定方法

采用分光光度法探索测定异α 酸、四氢异α 酸异构体、六氢异α 酸异构体等酒花制品中异α 酸的浓度 ,利用该方法对已知标准样品中异α 酸浓度进行检测 ,其重复性与精密度的结果表明 ,该方法的变异系数≤ 1 %,回收率在 99 8%～ 10 0 5 %之间 ;方法操作简单 ,可作为啤酒企业衡量评价异α 酸、四氢异α 酸异构体、六氢异α 酸异构体等酒花制品中异α 酸浓度的检测方法