Development of Aroma Hop Cultivars in New Zealand*

Aroma hops of central Europe have traditionally been regarded as the benchmark for brewing. As population density and plant disease problems have arisen in Europe, other areas of the world have begun the development and production of aroma hops to suit the brewer's traditional specifications. Unfortunately these “noble aroma” cultivars did not readily translocate to other growing areas, including the Southern Hemisphere. New Zealand's 50-year-old hop research programme is producing “fingerprint” replicas of the noble aroma hop cultivars, now being used commercially by international brewing companies. The New Zealand aroma hop research programme concentrates on cultivars using the traditional Hallertauer mittelfrueh, Saazer, Tettnanger, Fuggle, Golding and Spalter varieties as parents in its breeding.     

酒花中萜烯醇类化合物的研究进展

酒酒花添加可赋予啤酒特有的风味,使酒体丰满协调。萜类物质对酒花风味的贡献发挥着重要作用。其中,萜烯醇类物质（如里那醇、香叶醇、β-香茅醇、α-萜品醇、橙花醇等）是影响酒花香气的关键性成分,其在发酵过程中含量的微小变化对啤酒的品质及感官评价影响很大。啤酒中的萜烯醇类物质不仅与酒花品种有关,还与发酵过程中的生物转化有关,甚至在储存时期也有变化。了解酒花中的萜烯醇类香气化合物在啤酒酿造过程中的含量及变化规律与控制和稳定啤酒的风味质量密切相关。该文就酒花中萜烯醇类物质的国内外研究现状做一综述。     

SIMULTANEOUS DETERMINATION OF α, β AND ISO-α ACIDS IN HOPS AND HOP PRODUCTS

A method for the simultaneous analysis of α, β and iso-α acid in hops, hop extracts and isomerised hop extracts is described. It is based on the use of reversed phase high performance liquid chromatography and quantitative evaluation of the hop compounds is carried out with a computing integrator. The isomerisation reaction can be examined in detail, particularly in connection with the production of hop derived haze forming compounds in isomerised hop extracts used for post fermentation bittering.     

STABILITY OF ESSENTIAL OIL OF HOPS

The stability of hop essential oil in beers, in hops and in aqueous emulsions has been investigated. Hop character of beers treated with hop oil emulsion has stability on pasteurization and storage similar to that of dry hopped beers. When bottled with high levels of headspace air, beers lose hop character. Beers dry-hopped with stored hops or with hops damaged during pelleting tend to develop sulphury flavours. However, hop oil emulsions prepared from such hops give rise to a sound hop character in beer. Hop oil emulsion produced by the new process shows good stability physically, chemically and biologically, particularly when mechanically homogenized and stored under an inert atmosphere. The extent of any chemical alteration due to contact with air may be estimated spectrophotometrically.     

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。     

125th Anniversary Review: The Role of Hops in Brewing

Although hop technology has been a substantial part of brewing science for the last 130 years, we are still far from claiming to know everything about hops. As hops are considered primarily as a flavour ingredient for beer, with the added benefit of having anti‐microbial effects, hop research is focused on hops as a bittering agent, as an aroma contributor and as a preservative. Newer fields in hop research are directed toward the relevance of hops in flavour stability, brewing process utilisation, the technological benefits of hops in brewing as well as hops as a source of various substances with many health benefits. However the more we find out about the so‐called “spirit of beer” the more questions emerge that demand answers. While hop research was only an ancillary research field for decades, during the last ten years more universities and breweries have determined that hops must play a meaningful role in their research efforts. This article gives an overview of the up‐to‐date knowledge on hop aroma, hop derived bitterness, and the role of hops in flavour stability as well as light stability. Hop research is a wide field, therefore in this review only selected topics are reviewed. Other research areas such as hops utilisation, the antifoam potential of hops, or the advances in knowledge pertaining to the physiological valuable substances of hops go beyond the scope of this article.     

Characterisation of four popular Polish hop cultivars

Polish cultivars of hop (Humulus lupulus L.) are well known as aroma and bitter raw material in the brewing industry. To characterise four popular Polish hop cultivars, Lubelski (Lublin), Marynka, Sybilla and Iunga (also known as Junga), the essential oil profiles were determined by gas chromatography/flame ionisation detector (GC‐FID) and gas chromatography/chemical ionisation mass spectrometry (GC‐CIMS) and the alpha/beta acids amounts by high‐performance liquid chromatography/diode array detector (HPLC‐DAD) analysis. In addition, the multivariate statistical analysis of the volatile profiles was performed. The results obtained evidenced qualitative and quantitative differences between the four cultivars studied and the foreign hops described in the literature. Lubelski and Iunga showed the typical chemical profile of the fine‐aroma and high‐alpha cultivars, respectively. In Marynka and Sybilla, the average amounts of alpha acids were similar to the bitter hops, but with a volatile profile characteristics of the fine‐aroma and aroma cultivars respectively.     

啤酒酿造中欧盟的啤酒花供应特点

基于作者在国际啤酒花种植协会的活动和研究结果以及对相关文献的回顾,对欧盟的啤酒花产业结构、生产特点和欧盟啤酒花产业在世界啤酒行业的经济地位进行了综述。论述表明,欧盟啤酒花产业结构发生了很大变化。以市场为导向的结构调整及改变更具竞争力。在2000年至2008年期间,欧盟主要啤酒花种植国家中啤酒花农场的数量大幅下降。导致几乎所有欧盟成员国农场的平均规模有所增加。为保证生产利润的最大化,啤酒花农场的专业化程度在增加,经营模式也逐渐向企业经营模式转变。     

酒花老化评价的研究进展

酒花是啤酒生产的重要原料,确定酒花新鲜度更是保证啤酒酿造质量的关键。本文综述了国内外关于酒花老化评价的研究进展,根据酒花老化过程中苦味物质(α-酸和β-酸)、多酚和香气物质的变化情况,阐述了目前评价酒花老化程度的指标,为建立更为准确的酒花老化评价体系的研究提供一些理论参考。     

酒花制品有效成分稳定性研究

以α-酸、β-酸、总黄酮、黄腐酚含量为指标,比较了真空包装的压缩啤酒花、颗粒啤酒花、啤酒花浸膏在20℃、4℃、-20℃避光贮藏120d的成分变化.结果表明,随着温度的降低,压缩酒花、颗粒酒花、酒花浸膏中有效成分变化幅度逐渐变小,其中酒花浸膏中有效成分变化幅度最小,在20℃、4℃和-20℃贮藏条件下酒花浸膏中α-酸变化幅度分别为13.82％、7.39％、3.38％,β-酸17.13％、11.18％、6.80％,总黄酮4.48％、2.19％、1.56％,黄腐酚10.09％、5.68％、4.21％,以-20℃贮藏条件下酒花浸膏变化幅度最小.     

Biologically Active Compounds from Hops and Prospects for Their Use

Although female cones of the hop plant (Humulus lupulus) are known primarily as raw material supplying characteristic bitterness and aroma to beer, their equally significant health‐promoting effects have been known to mankind for several thousand years and hop is a plant traditionally utilized in folk medicine. This paper summarizes the scientific knowledge on the effects of all 3 major groups of secondary metabolites of hops; polyphenols, essential oils, and resins. Because of their chemical diversity, it is no coincidence that these compounds exhibit a wide range of pharmacologically important properties. In addition to antioxidant, anti‐inflammatory, and anticancer‐related properties, particular attention is being paid to prenylflavonoids that occur almost exclusively in hops and are considered to be some of the most active phytoestrogens known. Hop oils and resins are well known for their sedative and other neuropharmacological properties, but in addition, these compounds exhibit antibacterial and antifungal effects. Recently, alpha bitter acids have been shown to block the development of a number of complex lifestyle diseases that are referred to by the collective name “metabolic syndrome.” Information presented in this review confirms the significant potential for the use of hops in the pharmaceutical industry and provides an understanding of beer as a natural drink that, although moderately consumed, may become a source of many health‐promoting compounds.     

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.     

THE EFFECT OF HOP SUBSTANCES ON THE PRODUCTION OF FUSEL OIL

Unhopped beers contain more fusel oils than the corresponding normally hopped beers when certain strains of yeasts are used during fermentation. Water soluble fractions of hops and some soft resin constituents can influence fusel oil production. When hops are completely replaced by isomerized hop extracts the use of some additional hop fraction in the copper leads to the resulting beer having a similar fusel oil content to one hopped in the usual way. Partially hopped beers (0·25 lb./brl.) usually have similar fusel oil contents to beers produced using the normal quantity of hops (1·0 lb./brl.).     

酒花香气成分的检测及富含典型酒花香气啤酒的试验研究

单萜类物质是贡献啤酒酒花香气的重要成分。本研究在100L中试规模,原麦汁浓度为14°P,苦味质为20BU的条件下,从不同酒花添加工艺、添加量和品种三方面分析了啤酒中8种单萜类酒花香气物质的含量,并进行感官品评,发现在发酵罐中添加l％o香花的效果最好,啤酒风格因酒花品种不同而有异。8种酒花香气物质中里那醇、香叶醇、口．香茅醇和α-萜品醇最为重要,其啤酒中的含量与酒花中里那醇和香叶醇含量密切相关,前三者与前人研究-致,但本研究发现“α-萜品醇”也是重要香气物质之-。但啤酒中的酒花香气物质含量高,酒花香味不-定强,这可能与其构型有关,因此,又研究了三种酒花在啤酒酿造过程中酒花香气物质的同分异构体,包括（R）-（-）-里那醇、（S）-（＋）-里那醇、（-）-α-萜品醇、（十）-α-萜品醇、（R]-（＋）-卢-香茅醇、（S）-（-）-卢-香茅醇的含量。研究发现酒花品种的差异会引起同分异构体含量及比例的显著差异,加上其阈值的变化。进-步验证了同分异构体对啤酒中酒花香味的影响。     

Changes in the composition of hop secondary metabolites induced by high hydrostatic pressure

Hops contain large amounts of secondary metabolites, many of which have notable bioactive and sensory characteristics. Many of these properties are affected by the processing of raw hops into products. We studied the influence of high‐pressure processing (HPP) on the content and composition of secondary metabolites in hop homogenates prepared from fresh green cones of several Czech hop varieties. Homogenates contained more hop oils (27% on average) compared to dried hops. The composition of essential oils in homogenates after HPP showed a decrease in fatty acid methyl and thioesters fractions (80 and 100% respectively). Conversely, the number of other bioactive compounds from the group of resins and prenylflavonoids that remained in HPP homogenates was retained to a greater extent than in the dried hops. Low temperatures and an oxygen‐free atmosphere were effective conditions for the preservation of raw hops and hop products. Copyright © 2018 The Institute of Brewing & Distilling     

ANALYSIS OF HOPS OF THE 1987 CROP

Analytical values for α-acid content, as measured by lead conductance value, of twelve varieties of hops from the 1987 crop are presented in relation to the district of production. Satisfactory variabilities have been achieved by Fuggle, Progress, Bramling Cross, Northern Brewer, Zenith, Wye Challenger and Omega. Wye Northdown has increased in variability, reaching the upper limit of acceptability despite an increase in sampling rate. Goldings, W.G.V. and Wye Target have continued to show higher than normal variabilities. This year Yeoman has moved in variability above the acceptable limit. The sampling rates have been considered and in view of the unusual growing conditions experienced with the 1987 crop, with hop yields considerably reduced and α-acids increased to very high levels, no changes have been recommended.     

Hop maturation and resin formation: Field trials

The resin and essential oil contents of hops (Humulus lupulus L., var., Pride of Ringwood) together with cone weight were studied over a period of 4 weeks prior to and 1 week subsequent to the estimated time of normal harvesting. The petrol ether- and methanol-soluble fractions of the hop cone showed no significant change during this period. Essential oil and α-acid contents increased gradually over the sampling period, whilst cone weight increased up to the estimated time of normal harvesting and decreased thereafter. The results indicate that, with the particular variety studied, harvesting could have been conducted over a 4-week period without significantly affecting α-acid or hop cone yield. The advantages of harvesting high-yielding hops over a 4-week period rather than planting an earlier maturing but lower-yielding variety are discussed.     

TRACE VOLATILE CONSTITUENTS OF BEER. HOP SEED OIL

The fatty acid profile of hop seed oil has been examined and shown to be very similar to the fatty acid profile of the lipid fraction of both hops from which the seeds have been removed and seedless hops. The fates of the hop lipids and in particular the fatty acid fraction, both in conventional hopping procedures and in the preparation of an isomerised extract are discussed with reference to their possible effect on beer flavour.     

香型酒花对啤酒酿造质量的影响

啤酒花有两种基本类型:苦型和香型酒花.它赋予啤酒特有的苦味和香味,同时也影响啤酒的泡沫形成;酒花中含有酒花树脂、酒花油和多酚物质.本文主要就香型酒花在啤酒酿造过程中的风味变化以及对啤酒香味质量的影响进行了讨论.