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Cerevisia 36 (2012) 135–139 Contents lists available at SciVerse ScienceDirect Cerevisia j o ur nal homep age : w w w.e l sevier.com/locate/cerevisia and www.cerevisia.eu Abstracts of Related Journals With the collaboration of Luc De Cooman, Koen Goiris, Barbara Jaskula-Goiris Anne Pietercelie, Benny Van Heule, Anita Van Landschoot & Filip Van Opstaele Kaneda H., Kojima H. & Watari J.: Novel Psychological and Neurophysiological Significance of Beer Aromas. Part I: Mea- surement of Changes in Human Emotions During the Smelling of Hop and Ester Aromas Using a Measurement System for Brain- waves Journal of the American Society of Brewing Chemists, 2011, 69 (2): 67–74. Changes in human emotions during the smelling of hop and ester aromas were assessed using a measurement system for human brainwaves. Brainwaves were detected through a headband sensor equipped with two electrodes placed on the subject’s forehead. The detected brainwaves were transmitted to a notebook computer by a small electroencephalography amplifier and digitally filtered to extract alpha-wave components. Spec- trum information on the frequency fluctuation of alpha-waves calculated for each individual was related to psychologically evaluated values of positive/negative moods, feelings of arousal, and degree of comfort to identify associations between the values of fluctuation characteristics and psychological conditions. It was found that the aromas of essential oil extracted from Saarzer hops exhibited a significant relaxing effect (lowering arousal) on subjects. Linalool and geraniol had a significant relaxing effect on subjects, but -humulene and myrcene did not. Esters, a mixture of ethyl and isoamyl acetates, also had a significant relaxing effect on subjects. The measurement of brainwaves is a novel approach to determine the psychological and neurophysiological significance of the effects of smelling beer aroma components on changes in human emotions. Kaneda H., Kojima H. & Watari J.: Novel Psychological and Neu- rophysiological Significance of Beer Aromas. Part II: Effects of Beer Aromas on Brainwaves Related to Changes in Human Emo- tions Journal of the American Society of Brewing Chemists, 2011, 69 (2): 75–80. Changes in human emotions while smelling beer aromas were assessed using a measurement system for human brainwaves. The frequency fluctuation in the right frontal -waves while smelling beer was dependent on the beer brand and showed a significant correlation with feelings of arousal (relaxed and refreshed feel- ings) upon sensory evaluation. A pilsner-type beer with an aroma characterised by hops had a relaxing effect on subjects compared with domestic beers and stout. An all-malt beer with an aroma characterised by esters had a relaxing effect on subjects compared with domestic beers. The frequency fluctuation in the right frontal -waves while smelling beer also showed a significant correlation with the intensity of hop or ester aromas measured in the sensory evaluation. Thus, hop and ester aromas in beer were expected to contribute to an increase in feelings of relaxation while drinking beer. Patel J.K., Speers R.A. & Lake J.C.: Colloidal Examination of Worts Associated with Premature Yeast Flocculation Journal of the American Society of Brewing Chemists, 2011, 69 (2): 81–90. This paper reports on a study of the colloidal properties of yeast fermented in control and premature yeast flocculation (PYF) worts. A lager yeast strain was fermented in both control and PYF worts and analysed for cell wall properties. Yeast from the PYF wort exhibited more flocculation than the control. The PYF fermentation yielded yeast with less negative zeta potential than the control. When both yeasts were resuspended in beer (filtered through a 10 kDa filter), there was no difference in the surface charge of the control and PYF yeasts. This suggests that wort colloids or trub larger than 10 kDa caused a reduction in surface charge. Cell separation forces estimated by floc breakup through a capillary indicated PYF yeast flocs exhibited higher apparent separation force. A physical mechanism of PYF has been proposed that involves electrostatic interaction between wort particles (positively charged toward the end of fermentation) and yeast (negatively charged through fermentation). Forssell P., Treimo J., Eijsink V.G.H., Faulds C.B., Collins S., Schols H.A., Hinz S.W.A., Myllymäki O., Tamminen T., Zoldners J., Vila- nen K., Waldron K.W. & Buchert J.: Enzyme-aided Fractionation of Brewer’s Spent Grains in Pilot Scale Journal of the American Society of Brewing Chemists, 2011, 69 (2): 91–99. Brewer’s spent grain (BSG) is an important coproduct of the brewing industry and is generally used in animal feed. Recently, there has been considerable research into the use of enzymes to convert BSG into more value-added products. In this study, the efficiency of enzymatic fractionation of freshly produced BSG was studied in pilot scale. Carbohydrate- and protein-degrading enzymes were applied sequentially to produce three fractions: 1373-7163/$ see front matter doi:10.1016/j.cervis.2011.12.002

Abstracts of Related Journals

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Page 1: Abstracts of Related Journals

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Cerevisia 36 (2012) 135–139

Contents lists available at SciVerse ScienceDirect

Cerevisia

j o ur nal homep age : w w w.e l sev ier .com/ locate /cerev is ia and www.cerev is ia .eu

bstracts of Related Journals

With the collaboration of

Luc De Cooman, Koen Goiris, Barbara Jaskula-Goiris Anneietercelie, Benny Van Heule, Anita Van Landschoot & Filip Vanpstaele

Kaneda H., Kojima H. & Watari J.: Novel Psychological andeurophysiological Significance of Beer Aromas. Part I: Mea-

urement of Changes in Human Emotions During the Smellingf Hop and Ester Aromas Using a Measurement System for Brain-aves – Journal of the American Society of Brewing Chemists, 2011,

9 (2): 67–74.Changes in human emotions during the smelling of hop

nd ester aromas were assessed using a measurement systemor human brainwaves. Brainwaves were detected through aeadband sensor equipped with two electrodes placed on theubject’s forehead. The detected brainwaves were transmitted to aotebook computer by a small electroencephalography amplifiernd digitally filtered to extract alpha-wave components. Spec-rum information on the frequency fluctuation of alpha-wavesalculated for each individual was related to psychologicallyvaluated values of positive/negative moods, feelings of arousal,nd degree of comfort to identify associations between the valuesf fluctuation characteristics and psychological conditions. It wasound that the aromas of essential oil extracted from Saarzerops exhibited a significant relaxing effect (lowering arousal) onubjects. Linalool and geraniol had a significant relaxing effect onubjects, but �-humulene and myrcene did not. Esters, a mixture ofthyl and isoamyl acetates, also had a significant relaxing effect onubjects. The measurement of brainwaves is a novel approach toetermine the psychological and neurophysiological significancef the effects of smelling beer aroma components on changes inuman emotions.

Kaneda H., Kojima H. & Watari J.: Novel Psychological and Neu-ophysiological Significance of Beer Aromas. Part II: Effects ofeer Aromas on Brainwaves Related to Changes in Human Emo-ions – Journal of the American Society of Brewing Chemists, 2011,9 (2): 75–80.

Changes in human emotions while smelling beer aromas weressessed using a measurement system for human brainwaves. Therequency fluctuation in the right frontal �-waves while smellingeer was dependent on the beer brand and showed a significant

373-7163/$ – see front matteroi:10.1016/j.cervis.2011.12.002

correlation with feelings of arousal (relaxed and refreshed feel-ings) upon sensory evaluation. A pilsner-type beer with an aromacharacterised by hops had a relaxing effect on subjects comparedwith domestic beers and stout. An all-malt beer with an aromacharacterised by esters had a relaxing effect on subjects comparedwith domestic beers. The frequency fluctuation in the right frontal�-waves while smelling beer also showed a significant correlationwith the intensity of hop or ester aromas measured in the sensoryevaluation. Thus, hop and ester aromas in beer were expected tocontribute to an increase in feelings of relaxation while drinkingbeer.

Patel J.K., Speers R.A. & Lake J.C.: Colloidal Examination ofWorts Associated with Premature Yeast Flocculation – Journalof the American Society of Brewing Chemists, 2011, 69 (2): 81–90.

This paper reports on a study of the colloidal properties ofyeast fermented in control and premature yeast flocculation (PYF)worts. A lager yeast strain was fermented in both control andPYF worts and analysed for cell wall properties. Yeast from thePYF wort exhibited more flocculation than the control. The PYFfermentation yielded yeast with less negative zeta potential thanthe control. When both yeasts were resuspended in beer (filteredthrough a 10 kDa filter), there was no difference in the surfacecharge of the control and PYF yeasts. This suggests that wortcolloids or trub larger than 10 kDa caused a reduction in surfacecharge. Cell separation forces estimated by floc breakup througha capillary indicated PYF yeast flocs exhibited higher apparentseparation force. A physical mechanism of PYF has been proposedthat involves electrostatic interaction between wort particles(positively charged toward the end of fermentation) and yeast(negatively charged through fermentation).

Forssell P., Treimo J., Eijsink V.G.H., Faulds C.B., Collins S., ScholsH.A., Hinz S.W.A., Myllymäki O., Tamminen T., Zoldners J., Vila-nen K., Waldron K.W. & Buchert J.: Enzyme-aided Fractionationof Brewer’s Spent Grains in Pilot Scale – Journal of the AmericanSociety of Brewing Chemists, 2011, 69 (2): 91–99.

Brewer’s spent grain (BSG) is an important coproduct of thebrewing industry and is generally used in animal feed. Recently,there has been considerable research into the use of enzymes

to convert BSG into more value-added products. In this study,the efficiency of enzymatic fractionation of freshly produced BSGwas studied in pilot scale. Carbohydrate- and protein-degradingenzymes were applied sequentially to produce three fractions:
Page 2: Abstracts of Related Journals

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ars during specific processing steps where sugar reactions areaccelerated (e.g. during the mashing process or wort boiling in

36 Abstracts / Cerevi

arbohydrate hydrolysate, protein hydrolysate, and a solid lignin-arbohydrate residue. To minimise microbial contamination,rocessing was performed at 60 ◦C for 4 h. In all, 14 and 36%f the original dry matter was liberated by carbohydrase androtease, respectively. The carbohydrate-degrading enzymeocktail produced cellulose- and hemicellulose-derived mono-nd oligosaccharides. The protease treatment released peptide-nriched hydrolysate. Approximately half of the original BSGolids were solubilised during the two-stage enzymatic process.lthough the protease efficiently released the majority of BSGroteins, the carbohydrate matrix was much less accessible tonzyme attack. The impact of scale-up to pilot scale was comparedith previous laboratory-scale studies, and the results were found

o be in good agreement. However, at this stage of the research,he relatively high enzyme dosage affects the process economics.

Siebert K.J.: Elements of Analytical Measurement in Brewing Journal of the American Society of Brewing Chemists, 2011, 692): 100–107.

A successful analytical method must measure an analyte ofnterest in a suitable matrix with adequate sensitivity, accu-acy, and precision. This requires an appropriate combination ofetector specificity and component resolution. Highly specificetectors require little or no separation of the analyte from otheronstituents. Specificity can often be achieved using a chemicaleaction. Detectors with low specificity need a high degree ofeparation of components before they can be applied. Minimaleparation into two fractions can be achieved with distillation,ltration, sedimentation, or extraction. Multivariate analysispplied to multiple measurements (e.g., NIR spectra) can achieveathematical rather than physical separation. The degrees of

pecificity and separation in brewing analytical methods areiscussed.

Layfield J.B., Phister T.G. & Sheppard J.D.: Characterization ofybrid Strains of Saccharomyces pastorianus for Desiccationolerance – Journal of the American Society of Brewing Chemists,011, 69 (2): 108–115.

This study examines the impact of desiccation on the viabilitynd fermentation performance of multiple strains of Saccha-omyces pastorianus. S. pastorianus is a hybrid resulting from aross between S. cerevisiae and S. bayanus. It has been proposedhat S. pastorianus can be categorised into two distinct types:. pastorianus-Saaz type, which has lost a significant amountf the genomic content contained within S. cerevisiae, and S.astorianus-Frohberg type, which has retained almost all of theenomic content of S. cerevisiae. Both types of S. pastorianus,long with S. cerevisiae and S. bayanus strains, were desiccatedy spray-drying and then rehydrated before assessing the extentf the damage to the cells. The viability of rehydrated culturesas determined using microscopic enumeration, capacitance,

nd plating. Fermentation performance was tested by inoculatingqual amounts of viable rehydrated cells into brewer’s wort andonitoring changes in cell count, carbohydrate utilisation, and

lcohol concentration until completion. The findings suggesthat S. pastorianus-Frohberg type is less tolerant to desiccationhan either S. cerevisiae or S. pastorianus-Saaz type. Selectionf the correct type of S. pastorianus for use in active dry yeastould reduce the possibility of contamination or extended laghases leading to stuck fermentations. Difference in dessicationolerance could be compensed for by culturing the strain prior to

itching as subsequent generations of cells recover from the effects.

(2012) 135–139

Mayer H., Marconi O., Peretti G., Sensidoni M. & Fantozzi P.:Investigation of the Suitability of Hulled Wheats for Malting andBrewing – Journal of the American Society of Brewing Chemists,2011, 69 (2): 116–120.

Hulled wheats (einkorn, emmer, and spelt) are gaining interestin Italy as wholesome, tasty grains that are linked to the land andtradition. Their use in products like biscuits, pastas, and breads isalready well established, but there are fewer reports on their usefor malt and beer. This study analysed three Italian varieties ofTriticum dicoccum and one cultivar of T. monococcum with regardto their suitability to be malted and used as brewing raw mate-rials. The unmalted grain quality parameters investigated weremoisture, 1000-kernel weight, total protein content, 1000-spikeletweight, germinative energy, water sensitivity, high molecularweight beta-glucan content, amount of unhulled kernels, huskcontent, and vitreous and floury structure of the endosperm.After these parameters were measured, all of the samples weremalted. Before the malting trials, a study of water uptake was per-formed, and different steeping cycles were conducted to achievea steep-out moisture of 47%. The resulting malts were analysed,and the following parameters were determined: moisture, extract,saccharification time, extract difference, total nitrogen, solublenitrogen, Kolbach index, free amino nitrogen, viscosity, apparentfinal attenuation, diastatic power, pH value, malt colour, highmolecular weight �-glucan content, and wort obtained aftermashing.

Kunz T., Lee E.J., Schiwek V., Seewald T. & Methner F.-J.: Glucose– a Reducing Sugar? Reducing Properties of Sugars in Beveragesand Food. Brewing Science – Monatsschrift für Brauwissenschaft,2011, 64 (July/August), 61–67.

The properties of sugars and the mechanisms of carbohydratereactions in food and beverages at a low pH environment suchas jam, juice, wine, beer, honey, etc. are becoming increasinglyinteresting. Especially the properties of reducing sugars and theirindividual reduction potentials are important in relation to theshelf life of beverages and also their role in human nutrition. Evi-dently, fermentable sugars are to be considered, especially duringwort boiling where the reactions of sugars are accelerated. Fur-thermore, non-fermentable sugars are currently used in order toimpart unique flavour, body and mouthfeel to the beer. The pre-sented research proves that the original Chapon method is notsuited to determine the reduction potential of sugars in the lowpH range of food and beverages. However, when varying differ-ent parameters, it was found that the functional principle and thebasic reaction mechanism of the Fe3+ reduction can be used toobtain information on the reduction potentials of sugars withinlow pH areas at different temperatures and storage conditions.The implementation of this adapted method showed that sugarsbehave differently at low pH than under the described param-eters in the Fehling test when using NaOH. At low pH (4.3),the strongest reduction potential was achieved with isomaltulose(PalatinoseTM), followed by fructose, Vitalose® and maltotriose.The lowest reduction potential was detected with glucose, sucroseand polydextrose. As a result, this work shows that the optimisedChapon method may be used in the future for additional inves-tigations at different temperatures and low pH values between2.5 and 5.2, to get further evidence on the behaviour of sug-

brewing).

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Abstracts / Cerevi

Schwarz C., Zarnkow M., Back W. & Becker T.: Predicting Hazetability in Wheat Beer using Light Scattering Analysis Tech-iques. Brewing Science – Monatsschrift für Brauwissenschaft,011, 64 (July/August), 68–74.

A pronounced amount of haze is typical for German and Belgianheat beer styles and therefore represents an important quality

ttribute. The rising popularity of these naturally cloudy beer stylesas necessitated that they possess an extended shelf life as well as

prolonged haze stability. This is to ensure that when a customerurchases the beer, at least a satisfactory level of haze is evidentn dispense. However, predicting the haze stability of wheat beers still difficult because a reliable method has yet to be developed.n this work, light scattering analysis techniques and particle sizeistribution measurements were investigated, in order to predicthe haze stability of wheat beers. The results showed that increasedaze stability is associated with an increased ratio expressing the

ntensity of light scattering at 90◦:25◦. Furthermore, particle sizeistribution measurements demonstrated that samples with high0◦:25◦ ratios of scatter light intensity (>0.9), showed monomodalistributions with high ratios of particles <1 �m, which appears to

favourable indicator of beer haze stability.

Kunz T., Woest H., Lee E.-J., Müller C. & Methner F.-J.: Improve-ent of the Oxidative Wort and Beer Stability by Increasednmalted Barley Proportion. Brewing Science – Monatsschrift fürrauwissenschaft, 2011, 64 (July/August), 75–82.

The use of barley instead of malt in the brewing process seemsnteresting from an economic point of view, since the equipment,equired energy and human resources for malting entail greatosts. However, in the cost calculation it is important to considerhat unmalted barley has a significant enzyme deficit versus maltue to the lack of a germination process. Therefore, the addition ofechnically produced enzymes is required to compensate for thenzyme deficit during the brewing process. The aim of this studyas to get a deeper insight into the influences of unmalted barley

n the brewing process and on the quality of resulting beer-likeeverages with the main focus on the oxidative wort and “beer”tability. Therefore, traditional beer analyses according to MEBAK,uch as bitterness, colour, extract, foam stability, FAN, �-glucan,BI, etc., and EPR spectroscopy (measurement of oxidative stabilityEAP-value) and EPR signal intensity (T450-value)) were used inhis study. It was shown that an increase of the barley content inhe grist results in the inhibition of radical generation during therewing process and improved oxidative wort and beer stabilityithout a negative influence on the beer quality or sensory ratings.

urthermore, extra improvement can be achieved by optimizinghe concentration of technical enzyme addition. In conclusion,roduction of beers using up to 90% barley is not really a technicalroblem today due to the opportunities of available technicalnzymes on the market.

Maruhashi T., Gastl M., Becker T. & Narziß, L.: Auswirkungenon proteolyt Maischintensität auf die Bier. BRAUWELT, 2011,14,30–436.

Many newly introduced varieties of malting barley show excel-ent cytolysis and/or proteolysis properties. This offers potentialor processing in the malting plants, as the malting process can behorter and less intensive. The higher degree of cytolysis is due tohe fact that new malting barley varieties usually have a very highnzyme capacity. They show good results concerning amylolysis,ytolysis, and especially proteolysis. When the malting process

s altered to limit proteolysis, without considering amylolysis orytolysis, the brewer could however encounter difficulties in therewing process, for instance filtration problems due to insuffi-ient �-glucan decomposition. The aim of this research was to

(2012) 135–139 137

investigate the impact of different degrees of proteolysis, obtainedby variation in malting parameters, on the mashing process andthe final beer quality. For this purpose, barley from the samebatch was malted under different conditions. The malts obtained,with varying degrees of proteolysis, were used for brewing usingvarying brew schemes (both infusion and decoction, differentmashing-in temperatures). Beer quality and flavour stability of theresulting beers were evaluated by both (physico) chemical andsensory analysis.

Kappler S., Krahl M., Geissinger C., Becker T. & Krottenthaler M.:Degradation of Iso-�-Acids During Wort Boiling – Journal of theInstitute of Brewing, 2010, 116 (4): 332–338.

Boiling trials were performed to evaluate the degradationkinetics of isohumulones and the factors affecting the degra-dation. The boiling trials were conducted on a lab-scale withpurified iso-�-acids, at a concentration of 100 ppm. Degradationwas investigated as a function of time (0–90 min), temperature(80–110 ◦C), pH value (4–7), original gravity (10–18◦P) and ioncontent of the water (0–500 ppm Ca2+ and Mg2+). The recoveryrates of the isohumulones, as well as the cis:trans ratio and the rel-ative amount of iso-co-humulone were determined. The cis:transratio and co-iso-�-acid content did not change significantly. Byvarying the wort composition and the boiling parameters, lossesof isohumulones during wort boiling and wort treatment could bereduced. Boiling at atmospheric pressure for 90 min, comparableto a standard boil and hot wort treatment, led to losses of nearly25% within 90 min. These losses could be minimised by loweringthe temperature. High losses were also found when isohumuloneswere boiled at a low pH value, high original gravity and high waterhardness. By optimizing these parameters, losses of isohumulonesand thereby a decrease in less favourable bitter impressions canbe attained.

Lutterschmid G., Stübner M., Vogel R. F. & Niessen L.: Inductionof Gushing with Recombinant Class II Hydrophobin FcHyd5pfrom Fusarium culmorum and the Impact of Hop Compounds onits Gushing Potential – Journal of the Institute of Brewing, 2010,116 (4): 339–347.

Hydrophobins produced by various filamentous fungi areconsidered as biological gushing-inducing compounds. The studyshowed that the class II hydrophobin FcHyd5p, a hyphal surfaceprotein of the cereal pathogen Fusarium culmorum, is able toinduce gushing in beer and other carbonated beverages. FcHyd5pis heat stable and maintains its gushing inducing potential, whenboiled in synthetic wort. It was shown that gushing induced bypure FcHyd5p was susceptible to hop oils and modified iso-�-acidproducts and that the gushing volume can be decreased signifi-cantly by the addition of these substances.

Mfa Mezui A. & Swart P.: Effect of UV-C Disinfection of Beer –Sensory Analyses and Consumer Ranking – Journal of the Instituteof Brewing, 2010, 116 (4): 348–353.

Ultraviolet (UV-C) light irradiation is a non-thermal disinfec-tion technique. Using a pilot scale UV-C treatment system, trialswere conducted to investigate the effect of UV-C on beer withspecific attention to lightstruck flavour formation. Five differentbrands of beers were exposed to UV-C radiation at a 254 nmwavelength. Four beers were analysed by a consumer panel andone by a panel in a triangle taste test. Sensory and analytical data

revealed that lightstruck flavour formation appeared to be themain problem in beer regarding UV disinfection at 254 nm. The UVtreated beers were less liked, when compared to the non-treatedbeers. A sample enrichment probe technique coupledwith a gas
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38 Abstracts / Cerevi

hromatography–mass spectrometry (SEP/GCMS) revealed theresence of lightstruck flavour in all the treated beers.

Steiner E., Becker T. & Gastl M.: Turbidity and Haze Forma-ion in Beer – Insights and Overview – Journal of the Institute ofrewing, 2010, 116 (4): 360–368.

Several substances in beer are responsible for haze/turbidityormation: organic components such as proteins, polyphenols andarbohydrates (�- and �-glucans) and inorganic particles suchs filter aids and label remains. The study gives a survey of theifferent possibilities of haze formation and haze identification. Aeproducible and low cost analysis procedure, which can be carriedut with basic laboratory equipment, is proposed. The methods foraze identification include dyeing methods, microscopic analysesnd size exclusion chromatography.

Aron P.M. & Shellhammer T.H.: A Discussion of Polyphenols ineer Physical and Flavour Stability – Journal of the Institute ofrewing, 2010, 116 (4): 369–380.

It remains very difficult to comprehensively and accuratelyvaluate the ageing flavour of beer as no single compound or mea-urement exists to adequately address the multifaceted coursef ageing. Flavanoid polyphenols (PPs) such as the flavan-3-olsnd their condensed products, the proanthocyanidins, represent alass of readily oxidised compounds. As beer constituents they areirectly involved in haze formation and can be removed by PVPP.oth attractive and unattractive flavour properties have beenttributed to beer PPs. They also contribute significantly to theeducing power of beer. The review discusses the sources, contentnd impact of polyphenol presence and removal on beer physicalnd flavour stability.

De Clippeleer J., De Rouck G., De Cooman L. & Aerts G.: Influencef the Hopping Technology on the Storage-induced Appearancef Staling Aldehydes in Beer – Journal of the Institute of Brewing,010, 116 (4): 381–398.

The behaviour of the stereoisomers of the bitter acids wastudied in pilot beers at particularly high and low proportionsf the trans-iso-�-acids concentration relative to the cis-iso-�-cids concentration. Pure trans- respectively cis-isomers werebtained on a pilot scale by the separation of trans-iso-�-acidss �-cyclodextrin inclusion complexes from a commercial iso-erised hop extract. The trans-specific degradation could not be

inked to the formation of 2- methylpropanal, 2-methylbutanalnd 3-methylbutanal. A remarkable increase in the relative con-entration of cis-iso-�-acids was observed in the beers bitteredith purified trans-iso-�-acids, which may be ascribed to partial

onversion of trans-iso-�-acids via �-acids into cis-iso-�-acids.eer exclusively bittered with cis-iso-�-acids is not necessarilyore flavour stable. Aldehyde formation as a function of forced

geing was irrespective of the mode of bittering, emphasis-ng that malt quality and the brewing process itself are probablyhe most important factors regarding the flavour instability of beer.

Titze J., Christian M., Jacob F., Parlar H. & Ilberg V.: The Possibil-ties of Particle Analysis Demonstrated by the Measurement ofhe Colloidal Stability of Filtered Beer – Journal of the Institute ofrewing, 2010, 116 (4): 405–412.

The measuring methods for determination of long-term sta-

ility are: real time tests, predictive tests and indicative tests.he predictive forcing test, the most common used method, is aime-consuming method for accelerating beer ageing, e.g., at 0 ◦Cnd 60 ◦C. With a long-term forcing test over a period of 4 months,

(2012) 135–139

it was shown that the course of the hazing curve was in accordanceto the real time haze behaviour of beer with a lag, an increase, anda stationary phase. In addition, a significant difference betweenthe measuring point after the warm period and the cooling periodcould be observed and explained. The charge titration method wasdeveloped as an alternative to determine the particle charge offiltered beers, whereupon the relationship was elucidated betweenthe increase in hazing and decrease of potential along with theadvanced ageing of beer. The surface potential, as well as thesurface charge of the particles in beer, could be used as an indicatorfor colloidal stability. It was shown that a distinct relationshipexisted between haze increase (at 90◦) and the surface potentialdecrease or the titratable charge decrease. Although the initialsurface potential of both examined beer samples was similarlyhigh (for the less stabilised beer ∼ −450 mV and for the stronglystabilised sample ∼ −410 mV), the amount of particle surfacecharge was significantly higher in the less stabilised beer sample.This difference in the amount of surface charge could be the reasonfor the different stabilities. Furthermore, it was shown that it wasnot possible to draw conclusions on the long-term stability of beerusing only the haze value at the beginning of the measurement, asthe strongly stabilised beer had a higher start value of 1.3 EBC, incontrast to the less stabilised beer with a value of 0.32 EBC. Withthe help of the total charge, predictions are possible regarding thelong-term stability of the beer.

Panteloglou A. G., Box W. G., Smart K. A. & Cook D. J.: Optimiza-tion of a Small-scale Fermentation Test to Predict the PrematureYeast Flocculation Potential of Malts – Journal of the Institute ofBrewing, 2010, 116 (4): 413–420.

Tests for predicting the premature yeast flocculation (PYF)status of malts involve conducting a small scale fermentation test,which usually takes several days to be completed. The impact ofselected factors on the ability of such a test to distinguish fasterbetween PYF positive and PYF negative malts was investigated. Bysupplementing wort with 6 mg L−1 linoleic acid and using a highlyflocculent PYF sensitive yeast strain during the fermentability test,the PYF potential of malts could be predicted 40 h post pitching.These adaptations reduced the required time of analysis by 29 h.Besides shortening the required time of analysis, the considerationof the mechanism by which addition of linoleic acid enhanced theearly distinction between PYF positive and PYF negative malts mayprove useful in further elucidating the underlying causal factors ofthis complex phenomenon.

Veljovic M., Djordjevic R., Leskosek-Cukalovic I., Lakic N., Despo-tovic S., Pecic S. & Nedovic V.: The Possibility of Producing aSpecial Type of Beer Made from Wort with the Addition of GrapeMust – Journal of the Institute of Brewing, 2010, 116 (4): 440–444.

Must, from two different varieties of grapes (Prokupac andMuscat Hamburg), was added to conventional brewer’s wort. Thefermentation was according to traditional lager beer productionwith the entire process taking thirty days. The results obtainedsuggest that it is possible to produce a special type of beer madefrom wort and grape must with very interesting and pleasantsensory properties. The beers were characterised by an increasedalcohol (7–7.5% v/v) and real extract content, with sensory prop-erties similar to conventional beer, but with some peculiarities.

Van Opstaele F., De Rouck G., De Clippeleer J., Aerts G. & De

Cooman L.: Analytical and Sensory Assessment of Hoppy Aromaand Bitterness of Conventionally Hopped and Advanced HoppedPilsner Beers – Journal of the Institute of Brewing, 2010, 116 (4):445–458.
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appeared to have an important impact on this phenomenon.The correlation of the ratio of this value and the �-acid per-

Abstracts / Cerevi

In the study, analytical and sensory aspects of the hoppy char-cter of conventionally and advanced hopped Pilsner beers werevaluated. The level of markers for hoppy aroma (linalool andesquiterpenoids) depended on the applied hopping technologynd on the type of the hop oil fraction in the case of advanced hop-ing. Conventional aromatisation (late-hopping and dry-hoppingf advanced bittered beers) resulted in high linalool and sesquiter-enoid levels in the fresh beers. Advanced aromatising by hopssences mainly had a pronounced effect on the sesquiterpenoidevel. A high hoppy aroma intensity was not always reflected by

high level of linalool. It was found that linalool as well as otherop oil constituents were introduced into the beer when using an

so-�-acids extract for bittering purposes. The sensory impact ofdvanced hop aromatisation was not limited to beer aroma, but alsoffected bitterness perception and mouthfeel. During beer ageing,he linalool content did not decrease, whereas the sesquiterpenoid

evel decreased in all beers. Hop oil preparations may positivelynfluence the flavour stability of the resulting beers. Hop aromati-ation clearly masks the sensory perception of staling flavours.

(2012) 135–139 139

Müller M. P., Schmid F., Becker T. & Gastl M.: Impact of DifferentHop Compounds on the Overfoaming Volume of Beer Caused byPrimary Gushing – Journal of the Institute of Brewing, 2010, 116(4): 459–463.

The factors of primary gushing were investigated with vary-ing brewhouse parameters and the same “gushing malt”. Thespectrum of compounds in the finished beers thus only dif-fered through the hop product used. The overfoaming volumesof different samples were determined according to MEBAK.Hop oil and fatty acid concentrations (GC) and iso-�-acid con-tents (HPLC) were compared. The usage of different varieties ofhop pellets resulted in partially significant distinct overfoamingvolumes with addition at the start of wort boiling under con-stant parameters. The polyphenol content of the resulting beers

centage with the gushing volume revealed a high coefficient ofdetermination.