INSTITUTE OF BREWING HOPS ADVISORY COMMITTEE BREWING TRIALS WITH WYE CHALLENGER,WYE TARGET AND NORTHERN BREWER HOPS

The Wye Challenger hops brewed in the 1972 trial had higher α-acid contents but produced similar bitterness (EBU's) when brewed at similar α-acid-into-brew rates as Northern Brewer hops. On average the Wye Challenger hopped beers drunk slightly less bitter than the Northern Brewer hopped beers but, overall, drinkers indicated no preference between these beers. The Wye Target hops used in the 1972 trial came from four growths of varying α-acid contents. However, at similar α-acid-into-brew rates as used for Northern Brewer hops similar levels of bitterness (EBU's) were obtained. On average, the drinkers thought the Wye Target hopped beers drank slightly less bitter but were equally preferred on general flavour grounds to the Northern Brewer hopped beers. All breweries thought Wye Challenger, Wye Target and Northern Brewer suitable as a copper hop for at least up to 50% of the hop grist.     

HOP INDUSTRY ADVISORY COMMITTEE: BREWING TRIALS WITH WYE TARGET AND NORTHERN BREWER HOPS

Brewing trials with hops from the 1974 crop complete a three-year series in which Wye Target hops have been compared for brewing suitability with a control growth of Northern Brewer hops. Between 8 and 11 breweries took part each year. Physical examination of the hops used showed Wye Target to have less seed and to have a smaller cone size than the Northern Brewer but with a tendency to be loosely packed. When brewed at similar α-acid-into-brew rates as Northern Brewer hops, beers of similar analytical and flavour-assessed bitterness were produced. On general flavour grounds the beers were equally preferred. In all cases the Wye Target hops were rated as a copper hop either as equally suitable as, or more suitable than, the Northern Brewer hops.     

INSTITUTE OF BREWING HOPS ADVISORY COMMITTEE ANALYSIS OF HOPS OF THE 1972 CROP

Analytical values for 14 varieties of hops from the 1972 crop are presented in relation to the district of production. The tendency noted in 1971 for the variation within growths to diminish was continued in 1972. It was found that for Keyworth's Mid-season a sampling rate of 1 in 20 would be acceptable for commercial purposes.     

THE DETERMINATION OF RESIDUES OF ETHYLENEBISDITHIOCARBAMATES AND THEIR HOMOLOGUES IN HOPS

Residues of ethylenebisdithiocarbamate and homologous fungicides are determined by hydrolysis with boiling sulphuric acid and colorimetric measurement of the liberated carbon disulphide. By its nature, the method is not specific for individual fungicides of this type but is simple and considered suitable for the screening of hop intake samples. Following the proposed introduction of a contractual residue limit of 60 mg/kg, this method was used by various laboratories to survey the 1980 and 1981 hop crops.     

PILOT SCALE BREWING TRIALS WITH SEEDLESS YEOMAN AND ZENITH HOPS

Beers of sound flavour and quality have been produced on the pilot-scale using the new hop cultivars, Yeoman and Zenith.     

ON THE QUANTITATIVE HIGH PRESSURE LIQUID CHROMATOGRAPHY ANALYSIS OF TRICYCLODEHYDRO-ISOHUMULONE IN HOPS AND BEER

HPLC analysis detected very small or even zero amounts of tricyclodehydro-isohumulone in hops or lagers.     

COMMERCIAL BREWING AND STORAGE TRIALS WITH YEOMAN HOPS

Commercial brewing trials carried out with Yeoman hops from the 1981 crop have shown that these hops are suitable for producing both ales and lager beers. Seeded Yeoman hops show good storage characteristics and lost only 15·3% of their initial Lead Conductance Values after 44 weeks storage at ambient temperature.     

ANALYTICAL AND BREWING SIGNIFICANCE OF A TRICYCLIC OXIDATION PRODUCT OF HUMULONE (TRICYCLODEHYDROISOHUMULONE)

Tricyclodehydroisohumulone (TCD) is an oxidation product of humulone formed during storage of hops. It is about 70% as bitter as isohumulone, and considerably more stable, both chemically and in the brewing process. When used to bitter beer by addition to the copper the overall utilization of TCD is around 75% and the quality of bitterness is excellent. TCD is a normal constituent of beer brewed from old hops, and accounts for a part of the non iso-α-acid bitterness of such beers. TCD mimics iso-α-acids in some standard analytical procedures for bitterness determination, and interferes in others; the analytical significance is discussed.     

THE STORAGE OF YEOMAN HOPS AND PELLETISED POWDERS

Studies have shown that on extended storage of up to 90 weeks at ambient temperature pockets of Yeoman hops lose α-acids less rapidly than do the other varieties of English hops which are rich in resins. As expected the rate of loss of α-acids is further reduced when Yeoman hops are stored in the cold. Pelletised powders made from Yeoman hops show excellent storage characteristics when commercial packs are kept for 12 months either at ambient temperature or in the cold.     

LAGER BREWING ON THE PRODUCTION SCALE USING ENRICHED PELLETS MADE FROM SEEDED HOPS

Enriched pellets made from seeded Wye Challenger hops gave lager beers which could not be distinguished by analysis or by flavour from control beers brewed with enriched pellets made from seedless Hallertau Mittelfruh hops.     

DETECTION OF THE SULPHURING OF HOPS DURING KILNING AND CULTIVATION

Since brewing companies are now reluctant to accept hops treated with sulphur during kilning and cultivation, methods have been developed for detecting such contamination. In the procedure for estimating residual elemental sulphur, milled hops are continuously extracted with cyclohexane and dissolved sulphur is deposited on copper gauze as copper (I) sulphide. Hydrogen sulphide is then formed by the addition of hydrochloric acid and is absorbed in potassium hydroxide solution. The dissolved sulphide is finally estimated by titration using p-chloromercuribenzoic acid and diphenylthiocarbazone as indicator. The modified Monier Williams procedure, as recommended by the Institute of Brewing for estimating sulphur dioxide in beer, has been adapted for analysing hops. This provides a convenient technique for determining whether or not hops have been treated with sulphur or sulphur dioxide during kilning. The sulphur dioxide content of fresh hops treated at normal rates is of the order of 800 mg/kg. A number of samples of hops from the 1980 crop have been analysed and the levels of sulphur dioxide were found to be within the range 1 to 80 mg/kg. It is likely that these low levels are the result of using fuel oils, which contain variable amounts of sulphur, to dry the hops.     

THE STORAGE OF PELLETED POWDERS MADE FROM WYE NORTHDOWN HOPS

Pelleted hop powder from seeded Wye Northdown hops of the 1976 crop shows small losses in lead conductance value (LCV) when stored in commercial packs for ca. 12 months after processing. The losses for hop pellets stored at ambient temperature are slightly more rapid than for those stored at 0 to 4°C. Losses in LCV of pellets during storage in the cold or at ambient temperature are substantially less than those of seeded Wye Northdown cone hops stored in pockets under comparable conditions. The hop pellets showed no significant loss in oil content or bittering potential over the storage period. Taste panels were unable to detect differences in flavour when comparisons were made of beers bittered with pellets stored in the cold and at ambient temperature.     

CHANGES IN RESIN COMPOSITION AND BREWING BEHAVIOUR OF HOPS DURING STORAGE

Changes in resin components and brewing value of several varieties of hops stored at two temperatures have been examined. Different varieties and temperatures of storage gave rise to significant changes in resin and oil composition, but these variables had little effect on bittering capacity.     

INSTITUTE OF BREWING HOPS ADVISORY COMMITTEE ANALYSIS OF HOPS OF THE 1970 CROP

Analytical results for 6 varieties of hops from the 1970 crop are presented in relation to the district of production. It was found that values sufficient for commercial and industrial purposes can be obtained by sampling Bramling Cross at the rate of 1 sample from each 20 pockets and other varieties at 1 in 10.     

INSTITUTE OF BREWING HOPS ADVISORY COMMITTEE ANALYSIS OF HOPS OF THE 1973 CROP

Analytical values for 15 varieties of hops from the 1973 crop are presented in relation to the district of production. For most of these varieties the variation within growths was a little higher than in the 1972 crop. Nevertheless the results are quite acceptable for commercial purposes.     

BREWING TRIALS OF SEEDED AND SEEDLESS HOPS FROM THE 1969 CROP

This report describes the large scale trial of seeded versus seedless hops which was arranged on behalf of the Hops Liaison Committee. The objective of the trial was to detect whether there is a consistent difference between lagers brewed with hops containing seeds and lagers brewed with seedless hops. Two breweries each made three brews with the two types of experimental hops (both of the variety Northern Brewer) and with control hops. The lagers were tasted and/or drunk at eleven different centres, using the preference pair-comparison method, as it is the most sensitive method for detection of differences. In the principal comparison, of seeded versus seedless Northern Brewer, the preference results of both tasting and drinking panels indicate a significant and quite consistent difference between the two types of lager. This preference, expressed for the lager brewed with seedless hops, though statistically straightforward, was not so great that it can be concluded that any of the experimental lagers with either seeded or seedless hops was unacceptable to tasters or drinkers taking part in the trial. The difference may be partly accounted for by differences of bitterness. In the comparison of seedless Northern Brewer and the control there were inconsistencies in the direction of the differences detected, either between tasting and drinking panels or between the same comparisons made at different ages.     

THE INSTITUTE OF BREWING ANALYSIS COMMITTEE THE BREWING VALUE OF OLD HOPS. RELATIONSHIPS BETWEEN ANALYSES AND FLAVOUR

Beers were brewed with old and new hops and the relationships were studied between methods for estimating α-acids, beer bitterness and beer flavour. It was concluded that the α-acid content of hops at harvest is a simple and reasonably reliable guide to the brewing value of old hops; that the beer bitterness determined analytically is a good guide to that tasted; that beers brewed with old and new hops will differ little in bitter or harsh taste if the analytical bitterness levels are similar; and that tasters can distinguish between bitterness levels of 5 E.B.C. units at values around 30 units.     

THE USE OF GIANT-COLONY MORPHOLOGY FOR THE DIFFERENTIATION OF BREWING YEASTS

A simple, reproducible dilution/plating procedure is described for the production of giant-colonies of yeasts. The simplicity of the technique is such that the operator time necessary to perform the analysis is similar to that required by the Gilliland procedure and is less than one-quarter of the time required by the Hough method. Furthermore, the discrimination afforded by observation of giant-colony morphology exceeds even that of the Hough procedure. The problem of describing the morphological details of the giant-colonies has been partially solved by the recognition of 6 basic types of morphology. An incubation period of 10 days at 22° C, results in satisfactory giant-colonies with some yeast strains, but with others a 3–4 week incubation at 18° C. is preferable.     

HOP INDUSTRY COMMITTEE ANALYSIS OF HOPS OF THE 1983 CROP

Analytical values for α-acid content of thirteen varieties of hops from the 1983 crop are presented in relation to the district of production. For all varieties the tolerance aim of ±0·5% was achieved this year and variability of the crop was, in general, less than for previous years. As before, the results are acceptable for commercial purposes. The sampling rates have been considered and reductions in the rates for Bullion, Northern Brewer, Wye Northdown, Wye Target and Yeoman would be justified.     

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.