Brewing New Ideas.
FIRST TECHNICAL SESSION,
Thomas de Man, Moderator
Making Better Use of Sensory Panel Work
M.C. Meilgaard, Professor, International Consultant West Bloomfield, MI 48323 US
Brewers demand high accuracy and repeatability from chemical analyses, but they are much too lenient with regard to sensory measurements. A review of hundreds of published reports and brewery visits has shown that, with few exceptions, brewers fail to appreciate that a well-trained and well-run panel can deliver valid and reproducible verdicts. Most brewers load their best descriptive panels with thousands of routine tests while neglecting to take full advantage of the panels where it really matters. Using examples from a long consulting practice, the paper reviews how much panel verdicts can be improved. Use 10 - 20 assessors, not 6 or 8. Repeat important tests 3 - 5 times as you would an important chemical analysis. When publishing, report all results and their standard deviation. Report questions asked of the assessors. Report training standards used. Examples follow of the profitable use of such panels: Interpreting terminology and values of groups of consumers. Using all 14 sulfury terms in the Internati onal terminology. Measuring deviations from the standard profile of a brand. Tracking elusive flavor taints. Many other examples.
Flavor Characteristics of Liquid Adjuncts derived from Corn
Scott Helstad, National Acct. Tech. Ser. Mgr., Cargill, Inc Dayton, OH 45413 USA Co-author, Julie Cox, Sr. Scientist Cargill, Inc.
Liquid brewing adjuncts derived from corn are typically described as having a bland, semisweet flavor. However, there are other flavor notes present. The intensity of these notes vary and are a function of the processing techniques used to make the syrup. This paper will present a a fundamental overview of flavors commonly associated with corn derived liquid adjuncts.
Beer Flavor Stability The Impact Of Raw Materials
J.P. Murray, Senior Advisor, Brewing Research International, Lyttel Hall, Nutfield, RH1 4HY United Kingdom; Co-author: S. Chandra, Brewing Research International
Beer flavor stability is the extent to which a beer is able to resist flavor changes which are usually undesirable. Beer flavor stability is a crucial factor in maintaining brand integrity in the market place. BRI has identified a range of compounds inherent in the raw materials, which are important in controlling flavor deterioration of a brand. The compounds that affect the stability of the beer show good correlation with sensory perception of the stale character of a brand. We are able to conclude that different brands oxidize by subtly different mechanisms and this will be demonstrated. Using a range of analytical, GC-olfactometry and sensory techniques, the flavor changes in brands have been evaluated. The changes which occur during the shelf-life of brands have been compared to benchmark brands and their stability's. The compositional differences have been identified and linked to the raw materials with an aim to provide practical best practice guidelines for flavor stability. The impact of raw material s processing parameters (e.g. malt kilning regimes) and their role in providing the antioxidant activity to retard the staling mechanism will also be presented.
SECOND TECHNICAL SESSION,
Barry Axell, Moderator
Yeast Propagation and Storage Design for High Gravity Brewing (HGB)
Mike Cholerton, Technology/Sales Manager, Alfa Laval , Scandi Brew, Rosenkaeret 18, Soeborg, Copenhagen
With most breweries now maximizing production from existing plant by HGB or VHGB this paper reflects on the considerations required in Yeast Plant Design to facilitate successful/consistent yeast performance in an increasingly aggressive environment. This environment can leave even the most resilient yeast more susceptible to infection, mutation and damage. Inhibiting growth factors, yeast stress, subsequent fermentation problems and some implications on beer flavour will be the key issues. With HGB resulting in yeast being used for fewer generations, developments in Yeast Propagation and Storage Design will be discussed. For Propagation, different systems will be described (single vessel/batch, 2 vessel/semicontinuous and continuous ). Concerns that high cell growth/accelerated aeration has the potential to produce yeasts that are 'stressed' and detrimental to fermentation performance will be raised. For Storage, an optimum Yeast Storage Tank Design to prevent yeast degeneration, incorporating the correct mi xer specification/dimensioning, will be presented. New developments in Mixer designs for yeast will show 'Flow Propeller' types allowing circulation from flow and not turbulence. The new type of design uses flow circulation, reducing potential cell damage from turbulence caused behind the mixer blades. Also implications from tip speed, pumping and cooling rates will be discussed. Integrated Mixer/CIP systems that clean all the mixer parts, including behind the mixer blades would be included as well as implications from acid washing facilities.
The "Decke" and Yeast Vitality
Toshihiko Hon, Researcher, Kirin Brewery Co., Ltd
1-17-1, Namamugi, Tsurumi-ku Yokohama
Kanagawa 230-8628 Japan
Co-authors: Haruhiko Arimura, Takeo Imai, Yoko Yasuda, Mayumi Abe, Kirin Brewery Co., Ltd
It is a fact among brewers that yeast vitality plays an important role on the quality of finished beer. We have investigated the yeast handling technology in detail, including the storage temperature, the replacement of young beer with cold water, etc. In this presentation we report on another factor, "the decke", whose effect on yeast vitality has not been elucidated scientifically.
In laboratory tests using several vitality tests, we scientifically showed that the removal of "decke" from cropped yeast had an effect on yeast vitality. This effect was similar to that of lowering the yeast storage temperature by two degrees Celsius. The components of "decke", which affect yeast vitality, will be also discussed.
A Vitality-Oriented Yeast Management in the Suntory Kyoto Brewery with Recent Technology
Atsushi Fujita, Assistant Brewmaster, Kyoto Brewery, Suntory Ltd., Nagaokakyo-shi, Kyoto, 617-8530 Japan
Fine beer should be made only from good materials, vital yeast and a well-designed process. On this concept we have reconstructed the whole process with the keyword of "gentle handling" and our new brew house was presented at the WBC2000. In this presentation we will show our new yeast handling system.
For a good fermentation and for the constant production of high quality beer, the stress on the yeast should be minimized and the total yeast vitality should be controlled at an equally high level in each fermenter. From this viewpoint we have rebuilt our process, especially cropping, storage and pitching of yeast
First, we estimated the yeast vitality with their cytosolic pH during fermentation and decided the best point for cropping from the fermenter. Second, to prevent loss of yeast vitality during cropping and storage, newly designed cooler and storage tanks were introduced. Third, an on-line dielectric monitoring system was introduced for the precise control of pitching.
Through these improvements, both a highly constant vitality of pitching yeast and a constant production of high quality beer were achieved.
New Applications and Methods Utilizing RF Impedance Measurements for Improving Yeast Management in a Modern Brewery
John Carvell, Director, Aber Instruments Ltd., Science Park, Aberystwyth, Ceredigion Wales
Co-authors: Chris Boulton, Research Manager, Bass Brewers; Kirsty Turner, Research Associate, Aber Instruments Ltd ; Steve Cunningham; Technical Sales Manager, Aber Instruments Ltd.
RF impedance or capacitance measurements are used in many of the larger automated breweries for measuring the viable yeast cell concentration. In this paper the latest applications are reported for the ways brewers are using this measurement in either the yeast pitching main, the yeast recovery line or the fermentation vessels. The new methods include an electrode that can be either inserted into a production propagator and fermenter or submerged into a vessel to monitor the yeast concentration profile in real time. The paper also describes how RF impedance can be combined with a bulk fluorescence measurement to allow both the live and dead cell counts to be determined.
THIRD TECHNICAL SESSION
Joaquin Tresselt, Moderator
Beer Variables that Support Beer Foam
Michael Lewis, Professor Emeritus of Brewing
University of California, Davis, CA 95616 USA
Co-author: Ashton S. Lewis, Staff Masterbrewer Paul Mueller Company
Most research about beer foam has taken one of two general approaches. In the first, the foam has been separated from a large volume of beer, collapsed and then analyzed to determine its composition. The reasonable assumption is that foam-supporting materials will concentrate in the foam. In the second approach, researchers have added materials to beer and observed their effect on foam formation. These additions may be isolated fractions of beer itself or materials quite foreign to beer but with known properties and effects on foaming in other food systems. Reasonably then, the properties of foam supporting materials natural to beer can be predicted. As might be expected these two approaches have resulted two rather different views of foam-supporting materials in beer. The first approach (perhaps inevitably) leads to the concept of a singular foam-supporting protein, the barley lipid transfer protein, and the second approach, perhaps also predictably, leads to the concept of a class of hydrophobic proteins or protein complexes that support foam.
Dur approach to beer foam has been rather different because we did not see how using the same techniques as others, we could uncover more than they could and partly because we suspected that foam support was a multidimensional phenomenon that at least in part depended on the integrity of the product. We wished also to work with a natural pouring method to produce an ordinary foam on a glass of beer with a view to using sensory (human) input at some later date to judge foam quality. Finally, a method of foam analysis was described which we quickly came to trust (the method of Mark Constants) and which suited our objectives admirably. The method measures rather well what the eye perceives when observing foam. After an initial study of seventy or so different beer brands we selected 30 beers for the full study representing the range of beer types readily available in the domestic beer market place. Imported beers were excluded as we could not preclude the use of processing aids that would confound our analysis. The chosen beers included low-alcohol products, premium lagers, calorie-reduced beers, superpremium beers and domestic ales, and a range of specialty products from large and small producers. These gave a broad range of foam stability as measured by Constants' method. These beers were then analyzed for every variable we thought might relate to foam stability, and by a variety of methods e.g. for protein determination. Statistical correlations were then drawn between these analytical properties and foam stability. Our results in general do not contradict current theories but suggest what is implied above: that good foam arises from multiple sources.
Advances in Carbon Dioxide Purification For Beverage Applications
David Porter, Engineering Manager, Domnick hunter Ltd., Dukesway, Team Valley Trading Estate, Gateshead, Tyne NE11 0PZ UK
The problems of contaminated carbon dioxide (CO2) effecting the quality of carbonated beverages are well known after several, well publicized incidents. A significant drive to address gas quality has taken place over the last 2 years with a dramatic increase in online monitoring and the development of in-line 'gas polishers' acting as trace contaminant removal devices (see Fielding and Kelly 1).
These developments have focused on the beverage production plant, CO2 used at point of sale, e.g. for beer dispense, presents different problems, for example :- Large number of physical locations. Staff focused on customer service rather than plan maintenance Lower flow rates and operating pressures. The rational for a point-of-sale trace gas contaminant removal device is the same as for those fitted at the brewery / bottling plant, namely that the purchased CO2 supply may be of varying quality and any impurities, if present may effect the appearance and taste of the beer. In fact, certain contaminants may present a risk to consumers health. This paper will outline the history of development work carried out on a large scale CO2 polisher already in service in many beverage production plants around the world.
Additionally, this paper will present results of a series of tests (currently under way) of a small scale, in-line device designed to address the problems associated with point-of-sale applications given above. A specially produced mixture of CO2 and trace impurities is passed through the purifying device and the effluent gas monitored for the impurities. Concentration reduction figures over a time period will be presented. References will be made to the International Society of Beverage Technologists standards for CO2 and the recommended tests methods used for impurity analysis. References:- 1) R Fielding & S Kelly, 'Developments in Carbon Dioxide Purification for the Beverage Industry', ISBT Quality Control Technical Sub Committee for CO2 Specification. To be presented in main proceedings at BevTech 2001, Ft. Lauderdale.
Different Beers Require Different Silicas for Stabilisation
Presenter. Dr. Graham Stewart Professor International Centre for Brewing and Distilling Heriot-Watt University Edinburgh, Scotland
Co-authors: Ian P. McKeown Dr Crosfield Group, Warrington, England, UK. Graham J. Earl Dr Crosfield Group, Warrington, England, UK. Kenneth A. Leiper Mr International Centre for Brewing and Distilling, Heriot-Watt University, Edinburgh, Scotland, UK.
Colloidal instability is one factor responsible for determining beer shelf-life. This instability is usually caused by the formation of haze particles resulting from interactions between certain proteins and polyphenols. Silica gels can be used to selectively remove the protein fraction. Previous work has shown that haze-causing protein originates only from malt. Analysis of material recovered from saturated silica showed a range of small polypeptides composed largely of proline and glutamic acid and were similar in all beer types studied. Silicas of different structure behaved differently between various beer types, indicating that protein was not the only component being adsorbed. Further analysis showed that silica adsorbed material contained varying amounts of carbohydrate. The present study shows that this material is probably in the form of glycoprotein and that the amount present in beer is determined by mashing conditions. The nature of this material will influence silica efficiency as silicas with a particular pore size will be suited to material of a particular composition. Using this information, it is possible to select the most appropriate silica to provide the most efficient stabilization of individual beers.
Offline Foam Stability System Using Machine Vision Technologies
Andre Nothaft, General Director, Estr. dos Bandeirantes, 8075 Rio do Janeiro, RJ 22710-112 Brazil
Co-authors: Stephane Lemieux, Katia Jorge
In the brewing industry, the quality of the foam created in a glass is of the most importance for the perception of the clients but is also an indication of the quality of the beer. Even with the importance of foam appearance, to this date measurement of foam characteristics at the laboratory level is still done with a fairly low level of information regarding foam quality. Akitek has developed a foam stability tool with the unique ability to observe foam evolution at the bubble level providing an interesting optic into the challenging field of foam analysis. The system gives an accurate reading for the following foam parameters: * Foam collapse over time * Mean bubble size over time * Foam density over time * Final liquid level * Total collapse time * Image of foam over time. The resulting unit is an intelligent system capable of visually analyze the foam quality in beer.
FOURTH TECHNICAL SESSION, Mike Sutton, Moderator
Technological Musings and Applications of a Classical Brewmaster
Gary Luther, Consultant to the brewing industry and Miller Brewing Company (retired), Hartland, WI 53029 USA
Co-authors: Franz Kuehtreiber Technical Director (Ret.) and Partner, Hubertusbra, Hubertusbraeu, Laa a. d. Thaya, Austria
Dr. Franz Kuehtreiber, owner of the Hubertus Brau Brewery in Lass a. d. Thaya, is renowned in his geographic area for innovative, creative brewing solutions with regard to brewery equipment and technologies. This paper presents a number of Dr. Kuehtreibers significant technological applications. Many today are considered leading edge with respect to flavor and flavor stability. Issues discussed are the coolship effect, kraeusen balls, hop powder, hot wort filtration, lauter tun run off as well as muses on yeast and trub management.
Evaporating The Myths Of The Past
Zane Barnes, Brewmaster Briggs of Burton PLC Burton-on-Trent, Staffordshire DE142LH England
Co-authors: Warren Quilliam Strategic Brewing Consultant South African Breweries
Commercial beers (500-1500 hls) have been brewed, employing nucleate boiling, with kettle heater surface areas up to 5 times higher than the typical internal heater. This work was designed to establish the optimum kettle heater surface area that achieves the minimum evaporation compatible with required flavour and colloidal stability. Results demonstrate that nucleate boiling with a larger heater surface area can achieve major reductions in evaporation and energy consumption with no reduction in wort quality. This also allows much lower steam/wort temperature difference, and the number of brews between heater CIP can be increased from the more normal 6 to greater than 30. Retrofitting this high surface area heating technology to existing kettles is straight-forward.
Rapid detection of Yeast Contaminants
Sylvie Van Zandycke Project Manager Smart Brewing Services Oxford Brookes Enterprises Gipsy Lane Campus Oxford, Oxen OX3 0BP UK)
Co-authors: Rosy Cavaliere, Undergraduate Student Oxford Brookes University, Katherine A. Smart Reader/Managing Director Oxford Brookes University/Smart Brewing Services
Pitching yeast purity is an essential prerequisite to ensure fermentation performance and product quality. This is particularly relevant for serially repitched slurries which may be reutilised for 5-20 subsequent fermentations (medium to large scale breweries), indefinitely (in microbreweries) or until a contamination problem arises. Several methods of detection and identification of wild yeast and petite contaminants are available; however, these tend to rely on the development of colonies on slide or plate culture and involve the use of complex selective media. The disadvantage of this approach is the time taken for cell replication and colony formation to occur. In some cases as much as 7 days is required to achieve a confirmed result. Here we describe a rapid method using selective media to identify Saccharomyces and non-Saccharomyces wild yeast, petite mutants, ale and lager production strains.
FIFTH TECHNICAL SESSION,
Terry Kavanagh, Moderator
Environmentally Sustainable Alternative Uses for Brewery By-Products
Paul Bruijn, Environmental Specialist, Heineken Technical Services, Burgemeester Smeetsweg, Zoeterwoude, ZH 2382 PH The Netherlands
The preferred use for brewers' spent grains is as feed for ruminants. However, for some Heineken breweries, it is not possible to feed the spent grains to ruminants. As a result we have been seeking alternative uses for spent grains and other brewery by-products. In co-operation with 2B Biorefineries, a small Swiss company, we have been developing a process to separate the spent grains into a high protein fraction and a high fibre fraction. The high protein fraction is suitable for use as animal feed for pigs and poultry. The high fibre fraction is suitable for energy generation either by the brewery itself or by other energy producers. The energy produced is about 25 Mega-joules per hectolitre of beer produced, which is about 15-25% of the total energy needs of a modern brewery. The process is based on mechanical separations, uses proven equipment and is relatively flexible. Other brewery by-products such as surplus yeast, trub, malt dust and rest beer can be included in the process. Depending on local circu mstances, the process is both economically viable and environmentally sustainable.
Energy Savings with a New Style "Refrigerating Machine"
Hirano Nobuo, Sapporo Breweries, Shibuya-ku, Tokyo 150-8686 Japan
In 2000, Sapporo Breweries began the operation of new refrigeration equipment, which utilises the world's latest technology. Generating power below the freezing point had been impossible until the "absorption system refrigerating machine" which uses water and lithium bromide as the working media. The operation of this system, which is described in this presentation, also provides environmental benefits. Water and lithium bromide are considered to be safer than ammonia. Furthermore, unlike chlorofluorocarbons, there is no impact on the ozone layer. From the facts mentioned above, it can be described as a refrigerating machine which is designed to take the earth's environment into consideration. Sapporo breweries combines this refrigerating machine with co-generation and anaerobic wastewater treatment systems. By these measures, Sapporo has been able to maximise energy recycling regardless of the volume of steam used in processing
Integrating Commercial and Technical Activities to Leverage Packaging Materials Supply Chain Performance
Desire Vermeulen, Packaging Consultant, South African Breweries, Sandton, Johannesburg, Gauteng 2146 ZAR
Co-author: Christian Bekker Swart, Packaging Materials Development Manager, South African Breweries
This paper covers the work being done by the South African Breweries to control and improve packaging material supplier performance and outgoing quality. The total commercial and technical interface with packaging suppliers will be discussed, with focus on packaging supplier accreditation, grid analysis, six sigma and the TCO concept (total cost of ownership). Six sigma is being used as a measurement tool as South African Breweries does not conduct incoming inspections on packaging raw materials. The success using this system will be highlighted. The commercial and technical interface is very important and formal procedures such as packaging supplier accreditation and grid analysis are used for risk assessment as well as supplier development.
SIXTH TECHNICAL SESSION,
Bill Ladish, Moderator
Breeding Methods for the Development of Seedless Hops in New Zealand
Ron Beatson, Scientist, HortResearch, Motueka, Nelson 7161 New Zealand
Co-authors: Ross Ferguson Scientist HortResearch, Iona O'Brien Scientist HortResearch Mr Kevin Ansell Research Associate HortResearch, Lawrence Graham Research Associate HortResearch
The New Zealand hop industry relies on the breeding and development of seedless cultivars with triploid (3 sets of chromosomes) constitution. To obtain triploid cultivars, one parent used in crossing must be of tetraploid (4 sets of chromosomes) constitution. Tetraploids do not occur naturally and must be created. The traditional method of obtaining a tetraploid hop involves the use of the chromosome doubling agent colchicine. Another method, which has not been used in hop breeding, is to identify sexually derived tetraploids from seedling populations. The latter method offers a useful alternative method in that they are easier to obtain and are less in-bred than colchicine derived tetraploids. Sexually derived tetraploids are readily identified by flow cytometric methods. Sexually derived tetraploid parents have been successfully used to breed both high alpha- and aroma-type seedless selections. Trial data suggests the selections will offer the New Zealand hop industry a range of new cultivars with good comm ercial potential.
Dealing With Starch: A Scientific And Practical Analysis
Charles Bamforth Professor University of California Department of Food Science & Technology Davis, CA 95816 USA
Although starch is by far and away the most substantial component of brewery grist materials, only now is there an adequate understanding of its properties and digestion in relation to practical mashing operations. This review paper will summarize the current knowledge of the starch in barley and adjunct materials and the enzymes involved in its degradation. It will address certain dogmatic areas, such as the merits and de-merits of decoction mashing. It will also address the relevance of work performed on starch in other industries in relation to its relevance for brewhouse systems.
Relationship Between Fusarium Head Blight Infection and the Malting Quality of Barley
Paul Schwarz Associate Professor North Dakota State University Department of Cereal Science 1250 Bolley Drive Fargo, ND 58105 USA
Co-authors: Brain Steffenson, Associate Professor Department of Plant Pathology. University of Minnesota; Richard Horsley, Associate Professor Department of Plant Sciences. North Dakota State University; James Giullespie, Chemist Department of Cereal Science. North Dakota State University
The malting barley crop in the Upper Midwest USA has been devastated by severe epidemics of Fusarium Head Blight (FHB) during each of the past eight years (1993-2000). Infection of malting barley with this fungal disease is of considerable concern to maltsters and brewers because of production of the mycotoxin deoxynivalenol (DON), damage to grain yield and quality, and the potential for gushing in the resultant beer. The US industry has set very tight levels on DON as a means of regulating entry of FHB infected grain into the market. The objective of this study was to determine the relationships between the level of FHB infection and specific barley, malt and wort quality parameters, Commercial samples of Robust barley (150, N=2) were collected in eastern North Dakota during the 1996-2000 crop years. Samples were malted and standard quality parameters determined. Plate count (% infected kernels), DON and ergosterol were determined as markers of FHB infection. Relationship between markers of infection and qua lity parameters is determined by multiple linear regression.
SEVENTH TECHNICAL SESSION,
George Reisch, Moderator
New Canning Line in Suntory Kyoto Brewery with Advanced Technology
Masaaki Fujiwara, Project Engineer, Suntory Kyoto Brewery, Nagaokakyo, Kyoto 617-8530 Japan
In Suntory Kyoto Brewery, a new canning line with one hundred thousand cph capacity has been started in 2001. Various innovative technologies have successfully introduced into this line for high quality and high efficiency, such as (1) a filling technology, which enables very low oxygen uptake and very stable filled level (2) a information technology, which supports accurate traceablity and a just-in-time trend analysis for an high level quality assurance (3) a simple layout and robot technology, which enables a high productivity. In this paper, at first, we will discuss beer quality and its management system that greatly improved with the technological interpretations. Secondly, we will also refer to the technological factors that enable a high productivity so much 5 person per shift. Finally, we will present a computer-aided process information system and education system for the line manager in order to change their job style from only machine operation to the preventive action of facility maintenance and quality management.
Developing a High Performance FBI (Filled Bottle Inspection)
Takahiro Yamagishi, Packaging Engineering Department, Suntory Ltd., Osaka, Japan Co-authors: Shunichi Kitada Manager Packaging Engineering Department, Suntory Ltd. Toshiaki Tazawa General manager Packaging Engineering Department, Suntory Ltd.
Filling and crowning process might be making a damage of the neck finish accidentally. The defect bottles on a neckfinish, which cause a slow leak, have to be rejected completely. The filled bottle inspection (FBI) is necessary to detect the slow leak. This FBI uses the system which irradiates the ultrasonic wave from the bottom of the bottle. This system makes higher foam inside the bottle for leakbottle than for non-leak one. Moreover, this FBI employs the new illumination unit, which emits near infrared light to make transparent for dark color liquid and bottles including dark brown, green, and black. The infrared light can't pass the foam. Consequently, CCD camera takes a clear image of the foam, and FBI makes a clear distinction of the foam height between leak bottle and non-leak one. This new inspection system can detect a slight slow leak without any problems of liquid and bottle color.
A Novel Method Of Observing Compound Behavior by Using the Unique X-Ray Contrast Medium Compound
Hiroshi Hirao, Engneer, Research Laboratory F Kirin Brewery Co., Ltd. 1-17-1, Namamugi, TsurumiKu Yokohama, Kanagawa 230-8628 Japan
The measurements of sizes and the inspections of internal shapes usually do the quality control of can seaming. It is known that the compound acts an important roll against the leak from seaming part. However, the specification of the usage of compound has been only empirically determined due to lack of knowledge of compound behavior during seaming. We have successfully developed a
novel method of observing compound behavior by using the unique X-ray contrast medium compound for non-destructive X-ray seaming inspector. This method enables to develop the optimum compound design, including amounts, placements and application methods.
EIGHTH TECHNICAL SESSION,
Antolin Sierra, Moderator
Folkloristic Consideration On An Ancient Egypt Beer Manufacturing Process
Hideto Ishida, Advisory staff to General Mana, Kirin Brewery Co., Ltd. Shinkawa Chuo-ku, Tokyo 104-8288 Japan
Co-authors: Etsuji Tawada, Kirin Brewery Co., Ltd., Motoo Okouchi Kirin Brewery Co., Ltd.,
In order to explore the recipe of ancient Egypt beer, not only the conventional evaluation from brewer's eyepoint but evaluation from the life culture of the Egyptian people was performed. There are enzymes from human amylase and mold enzymes, enzymes from sprout seed, etc.in the world asenzyme more used for starch degredation from ancient times. The manufacturing method of the most suitable ancient Egypt beer is considered from record of the study of the ancient Egyptian's life, or of their used tools.
Major volatiles in beer determined by Head-space tandem to gas chromatography coupled to mass spectrometry (HS-GC-MS).
Mercedes G. Lopez, Professor, CINVESTAV, Irapuato, Gto. 36500 Mexico
Aroma plays a relevant role on the overall flavor of many food products. Therefore, the volatiles of twenty beers (seventeen Mexican and three imported) were determined using a tandem HS-GC-MS system. Five mL of each sample was incubated in 10 mL vials at 4 [degrees]C for 24 h. A 25 m(FFAP) capillary column was used during chromatographic separation. Among Mexican beers, one brand presented the highest number of volatiles within clear beers, however, among dark beers, a different brand showed more compounds. Nevertheless, tremendous similarities in C02 and ethanol concentrations were observed for all beers. Also, high similarities on beer volatiles were observed, the most abundant were alcohols (propanol, 2-methyl propanol, 3-methyl butanol, phenylethyl ethanol), acetates (ethylacetate, 3-methyl butanol acetate, phenylethyl acetate, S-ethyl etanethiolate), aldehydes (furfural), and esters (butanoic and octanoic ethyl esters) to mention some. None of the imported beers contained furfural and/or phenylethyl ace tate. On the other hand, only one Mexican brand showed furfural under the studied conditions. It can be concluded that the HS-GC-MS system is a highly reliable technique for the aroma analysis of beers.
Cost Effective, Recyclable Barrier Plastic Packaging Options for Beer
Nina Goodrich, General Manager, Amcor PET Technologies, Mississauga, Ontario L5C 2V5 Canada
Barrier options for beer in PET are evolving rapidly. There are a variety of alternatives available today at different price and performance points. Significant growth cannot occur until the price approaches the cost of current glass packaging. Amcor has developed a new approach to beer that is cost effective, increases performance for oxygen and carbon dioxide barrier and is recyclable. Recyclability will-increase in importance as the plastic beer bottle market share grows. Recycle technology is evolving toward direct contact bottle-to-bottle solutions. It is critical that both coloured and clear beer bottles be easily recyclable. This paper will discuss a new recyclable barrier technology forbeer and explain some of the challenges / opportunities for-recycling plastic bottles.
NINTH TECHNICAL SESSION, Alejandro Fierros, Moderator
The Impact of Diatomite Filter Aid on Beer Flavor
George Christoferson, General Manager - Quality Assurance, World Minerals Inc., Lompoc, CA 93438-0519 USA
Diatomaceous earth, also known as diatomite, or kieselguhr, has been used as a filter aid in the United States food process industry since 1913. There are references to diatomite filter aid in the U.S. brewing industry as early as 1914. Its use was generally limited prior to prohibition because of concern for its affect on taste. It gained acceptance in the production of "near beer" during the prohibition years (1920-1933). Following repeal, the U.S. brewing industry grew and with it high speed production. Diatomite filtration provided a method of clarifying efficiency that other technologies did not.
This paper follows the development of premium quality filter aids and their acceptance in the industry. As the market in North America has moved toward light-bodied beers, attention to the influence of contact materials on flavor has received increased attention, The impact of beer soluble iron and other metals as well as how they are monitored and controlled will be discussed, as well as what new developments can be expected in the future.
IAccelerated Production Of Lager Beer Using Ale Yeast.
Jean-Pierre Dufour, Professor, University of OTAGO, Food Science Department, Dunedin, New Zealand
Co-author: Russel Keast, University of OTAGO, Food Science, Department, Dunedin, New Zealand
Within the brewing process, much time is required for the steps of fermentation and maturation. Alteration of any fermentation/maturation parameter in order to achieve shortening of production time is only acceptable if no significant changes in beer quality are introduced. The most common way to accelerate the fermentation process is by using higher fermentation temperatures. Higher fermentation temperature, however, is known to alter levels of yeast-byproducts that make-up beer flavour. This work examines the production of beer main flavour compounds by lager and ale yeasts under identical conditions using 11[degrees]P lager wort. Increasing the fermentation temperature influenced the formation of aromatic alcohols to a higher extent than the aliphatic alcohols. The use of ale yeast, however, allowed a better control of the production of aromatic alcohols. Comparative analysis of lager and ale yeast amino acid metabolism indicated a reduced production rate of flavourf or the ale yeast Under all tested condi tions, attenuation at18[degrees]C was completed in 5-5 days with total VDK level lower than 80 ppb, with no VDK precursor detected.
The Impact of pH on Beer Flavour and Quality Revisited
David Taylor, Technical Director, Refresh UK Plc, Trowbridge,, Wilts. BA14 8HH UK
Control of pH throughout wort production, fermentation and maturation is probably the single most important process parameter influencing beer flavour and quality. It remains a sad fact that pH is taken for granted. It is more likely to be regarded as a consequence of brewing procedures rather than as the primary control governing not only enzymic and chemical reactions, but also influencing physical parameters, such as colloidal stability. One reason for this low level of respect for pH resides in the fact that its true nature (reflecting the concentration of hydrogen ions on a logarithmic basis) appears to be poorly understood. The influences of pH on beer quality are re-appraised in this paper, with illustrations provided of both direct effects on flavour (ie the impact of protons directly on taste receptors) and indirect actions by influencing the formation of many flavour congeners. In addition, recent investigations are described aimed at establishing the nature of factors influencing pH and their preci se relevance to beer production.
CLOSING TECHNICAL PROGRAM. Finn Knudsen, Moderator.
Award of Merit Lecture: "Innovation and Beer"
Inge Russell -- Labatt Brewing Co. Ltd., London, Ont Canada, N6C 2T6
Special Note: In addition to receiving the Award of Merit. Dr. Russell has been nominated to become Second Vice President of the MBAA. Her complete resume will be found elsewhere in this issue of The MBAA. Communicator.
Nick Huige and Inge Russell, Moderators
Chemical and Sensorial Analyses of Beers aged at Various Ph
Sonia Collin, Professor, Universite Catholique de Louvain, Unite Brasserie et des Industries Alimentaires, Croix du Sud,, 2 bte 7, Louvain-la-Neuve, B-1348 Belgium
Co-authors: Laurence Gijs, Universite Catholique de Louvain, Unite Brasserie et des Industries Alimentaires; Fabienne Chevance, Universite Catholique de Louvain, Unite Brasserie et des Industries Alimentaires ; Christine Guyot, Universite Catholique de Louvain, Unite Brasserie et des Industries Alimentaires
3-Methylthiopropionaldehyde was recently evidenced as the main source of dimethyltrisulfide, a key off-flavor in aged beer (Gus et al., JAFC, 2000). Its decomposition to methanethiol especially, occurs when pH is high, while trans-2-nonenal (cardboard flavor) is known to be produced at low pH. In the present work, dimethyltrisulfide, trans-2-nonenal, beta-damascenone, another suspected staling compound, esters and hops flavors were quantified in beers aged at various pH. As the consumer's view is determinant, all chemical data were further compared to sensorial analyses.
Influence of Lipid Oxidation during Wort Production on Beer Properties
Shingo Umemoto, Sapporo Breweries Ltd., Yaizu, Shizuoka 4250013 Japan
Activities of lipoxygenase (LOX) and lipase were changed according to the mashing method, which did not reduce the attenuation limit and the FAN level of the wort. LOX was inactivated faster than lipase during mashing. When the activities of these enzymes were lowered, the amounts of unsaturated fatty acids and trans-2-nonenal in wort were reduced. However, among the finished beers, there was little difference in the amounts of these substances. Taste and flavor stability of the finished beers were investigated and the significance of anti-oxidative brewing was considered.
Physiological Approach to Yeast Nutrient Development
Gary Spedding, Fermentation Analytical Services, Alltech Institute of Brewing and Distilling Inc., Nicholasville, Ky 43356 USA
Co-authors: Joseph Power, Brewing Research Director, Alltech Institute of Brewing and Distilling (AIBO); Tammy Dale, Analytical Services
Laboratory Manager, AIBO; Bill Lamm, Fermentation Specialist, AIBO
Brewers are demanding ever-higher concentrations of alcohol (and appropriate flavor production) in high gravity brewing situations. Effective yeast-nutrient formulas can aid yeast in circumventing osmotic- and higher alcohol induced stresses involved with high gravity worts. We have evaluated the effects of yeast cell walls (as a source of sterols) upon sugar utilization and ethanol production by brewers' yeast High gravity sugar solutions, supplemented with a base nutrient mix and additionally with increasing amounts of putative sterol donor were subjected to fermentation and monitored by means of HPLC analysis (sugar loss and alcohol production). Dose-dependent stimulation of fermentation was observed upon addition of yeast cell wall complex "sterol donor". Results showed 8.5% and 12% increases in alcohol production at 40 and 80 ppm putative sterol donor addition respectively. Pure sterols have been used experimentally in brewing research studies to stimulate yeast growth and activity. Our initial work with naturally derived "sterols/sterol donors" has proven rewarding and has now prompted further investigations.
Poster No. 4
Membrane Filtration for Bright Beer, an Alternative to Kieselguhr Filtration
Reinoud Noordman, Scientist, Process Development Heineken Technical Services, Burgemeester, Smeetsweg 1 Zoeterwoude, NL 2382 PH The Netherlands Co-authors: K. Tiktak, Manager Process Technology, Heineken Technical Services; C.J. Peet, Project Manager, Heineken Technical Services; L. Broens, Decision Director, Norit Membrane Technology; S. van Hoof, Manager, Development, Norit Membrane Technology
With respect to environmental and safety issues, it has been generally recognized that cross flow membrane filtration has the potential to be a good alternative to kieselguhr filtration. Membrane fouling, however, poses a significant drawback regarding process economics. Through a collaborative R&D project between Heineken Technical Services and Norit Membrane Technology, a new cross flow membrane filtration process has been developed. Through the use of a new oxidative cleaning agent, run lengths of more than 10 hours have been successfully maintained without affecting beer quality. Currently, the costs of membrane filtration for bright beer are about equal to those for kieselguhr filtration (about? 0.45 per hectoliter). It is expected that continuing efforts to optimize the process will reduce the costs of membrane filtration.
Poster No. 5
Flow Cytometric Analysis of Yeast Cell Cycle During Fermentation
Kenichiro Izumi, Kirin Brewery Co., Ltd., Research Laboratory for Brewing, Yokohama, Kanagawa 230-8628 Japan
Co-authors: Takeo lmai, Yutaka Ogawa, and Motoo Ohkochi, Kirin Brewery Co., Ltd., Research Laboratory for Brewing, Yokohama, Kanagawa 230-8628 Japan
The yeast cell cycle can be analyzed using flow cytometry, but it has been difficult to measure both DNA and RNA at the same time. We have developed a flow cytometric technique, which enabled us to analyze both DNA and RNA at the same time. It was found that RNA was synthesized before DNA and the synthesis of RNA corresponded to yeast cell budding. There exists an important relationship between yeast vitality and RNA/DNA synthesis of individual cells. The relationships of RNA/DNA synthesis and beer quality, and fermentation activity, will also be discussed.
Poster No. 6
The New Development of an Intelligent Simulator for Designing the Filtration and Bright Beer Tank (BBT) Process
Yusuke Umezawa, Brewing Engineer, Kyoto Brewery, Suntory Limited, Nagaokakyo-shi, Kyoto 617-8530 Japan
In large breweries, due to the production of various kinds of beer brands in many types of containers, following sales fluctuations, we hardly strictly predict the sales amount of each product and make their production schedules. Though BBTs generally have an important role to adjust both production schedules of filtration and packaging in such cases, we usually don't have a standard formula to calculate the required capacity of BBTs. This is the reason why we often meet the problem, such as an excess investment in sufficient capacity in filtration and BBT process. To solve this problem, we have developed an intelligent process simulator for process design from filtration to packaging, which gives the time course of the BBT status (beer type, liquid level numbers of standby and CIP tank etc.) with the input of the production schedule of filtration and filling. This has made it possible to estimate the capacity of filtration and the BBT process, and to investigate the optimal process design with consideration of fluctuations in sales amounts.
Poster No. 7
Comparison of Beers by Near Infrared Spectroscopy (NIRS)
Mercedes G. Lopez, Professor, Cinvestav, Ira puato, Gto. 36500 Mexico
Near infrared spectroscopy is a fast, non-destructive, and inexpensive analytical technique that could be used to classify, identify, and authenticate a wide range of foods and food items. Therefore, the main purpose of this study was to examine if NIRS results allow discrimination among beers' origin and brand, Twenty beers, seventeen Mexican (three different brands) and three imported were analyzed by nearinfrared spectroscopy (NIRS). Spectra of eight mL of each beer were recorded over a range of 10,000-4,000 cm-1, 64 scans of five repetitions were collected and with a resolution of 4 cm-1. All spectra were analyzed using principal component analysis (PCA( and soft independent modeling class analogy (SIMCA(. Most Mexican beers were grouped based on the Brewing Company, with very few exceptions, and some subgroups were also seen within a Brewing Co. On the other hand, imported beers also formed their own group. Therefore, it can be concluded that the NIRS technique is a very useful tool to discriminate not o nly among Mexican beers (and Brewing Companies), but also from imported beers.
Poster No. 8
The Flavor Contributions of Kilned and Roasted Products to Finished Beer Styles
Mary Anne Gruber, Technical Services Director, Briess Malting Company, Chilton, WI 53014 USA
The American craft beer movement has revived age-old beer styles, duplicated traditional beer styles and created all new beer styles in its quest to introduce Americans to full flavored, fine crafted specialty beers. At the heart of these styles is flavor - flavor developed in large part from the generous and often creative application of specialty malts. Color and foam are the first noticed contributions of specialty malts to beer, followed by aroma. But it's the flavor and mouth feel of beer that define its style. And that flavor and mouthfeel are contributed by specialty malts - malts that range in color from light to red to black. Because each specialty malt is unique, it needs to be evaluated for its flavor, color and other contributions to a beer style. This poster will review the wide spectrum of specialty malts available and the contribution of specialty malt flavors to finely crafted specialty beers.
Poster No. 9
Effect of Arabinoxylans, Beta-glucans, and Dextrins on the Viscosity and Membrane Filterability of Beer
Paul Sadosky, Research Associate, North Dakota State University, Department of Cereal science, Fargo, ND 58102 USA
Co-author. Paul Schwarz, Associate Professor, North Dakota State University
High molecular weight substances in beer can cause filtration difficulties. The objectives of this research were to quantify the effects of arabi noxylan, beta-glucan, and dextrin on the viscosity and membrane filterability of a beer model solution. Filterability was determined using a modified Esser test, and viscosity was determined with a Brookfield rotational viscometer. It was found that addition of arabinoxylan, beta-glucan, and dextrin increased viscosity of the model solution. Dextrin had the most pronounced effect on viscosity. The molecular weights of arabinoxylan and beta-glucan were found to affect solution viscosity. Addition of arabinoxylan or beta-glucan decreased filterability of the model solution. Arabinoxylan had the largest effect Addition of dextrin did not decrease filterability. The molecular weights of arabinoxylan and beta-glucan were found to be important to solution filterability but less important than concentration. No significant interactions between the carbohydrates with respec t to viscosity or filterability of the model solution were found. Viscosity was found to be a poor predictor of filterability across the range of carbohydrate concentrations evaluated in this study.
Poster No. 10
Evaluation of Yeast under High Stress Conditions
Tammy Dale, Research Scientist, Alltech, Inc., Nicholasville, KY 40356 USA
Co-authors: Bill Lamm, Research Scientist, Alltech, Inc; Joe Power, Manager, Brewing and Fermentation Research, Alltech, Inc; Gary Spedding , Manager, Fermentation Analytical Services, Alltech, Inc.
Yeast strains more tolerant or more resilient to adverse growth conditions can be advantageous. Higher temperature fermentations finish more quickly. Stress tolerant yeast may be better able to tolerate higher sugar concentrations in high gravity fermentations. Substrates with higher sugar can produce more alcohol if yeast can tolerate the additional sugar. Three yeast strains were evaluated under high stress conditions of temperature and concentration. Fermentations were carried out at 30 to 40 degrees C (temperature stress), with 32% dextrin (osmotic stress) and with 32% glucose (glucose stress). Performance was evaluated on the basis of alcohol production. Two of the strains, which had been chosen as temperature resistant yeast, performed better than the third control strain under all three stress conditions. Yeast strains resistant to multiple forms of stress can be identified. The results suggest that a strain with both general stress resistance and good brewing characteristics might be developed and use d to improve the efficiency of brewing fermentation.
Poster No. 11
QTL Analysis of Malting Quality in the Harrington X Morex Cross
Luis Marquez-Cedillo, Researcher, Instituto Nacional de Investigaciones Forestales y Agropecuarias, Texcoco, Edo. de Mexico 56230 Mexico
Malting quality is a complex phenotype, which is slowly improved by conventional techniques. This study was conducted to determine the number, genome location and effects of QTL determining malting quality in the two North American barley quality standards. Using a doubled haploid population of 140 lines from the cross of Harrington x Morex, malting quality phenotype data sets from eight environments, and a 107-marker linkage map, QTL analyses were performed using simple interval mapping and simplified composite interval mapping procedures. Eleven QTLwere associated with five malting quality traits (grain protein percentage, soluble/total (S/T) protein ratio, alpha amylase activity, diastatic power and malt extract percentage). QTL for multiple traits were coincident The loci controlling inflorescence type (vsr 1 on chromosome 2 and int-c on chromosome 4) were coincident with QTL affecting all traits except malt extract percentage. The largest effect QTL, for grain protein percentage, SIT ratio, and diastatic power, were coincident with the vsr 1 locus. QTL analyses were conducted separately for each sub-population (six-rowed and two-rowed). Three new QTL were detected in the subpopulations. There were significant interactions between the vsr1 and int-c loci for grain protein percentage and S/T protein ratio. Results suggest that this mating of two different germplasm groups caused a disruption of the balance of traits. Information on the number, position and effects of QTL determining components of malting quality may be useful for maintaining specific allele configurations that determine target quality profiles.
Poster No. 12
Dynamic Low Pressure Boiling
Bernhard Vollhals, Huppmann GmbH, Kitzingen, Germany Co-authors: Rudi Michel, Huppmann GmbH; Jens Voigt, Huppmann GmbH
Dynamic low pressure boiling for wort production has been introduced for several years in the brewing industry. Recent developments show very positive results in the behavior of nitrogen compounds and flavour related indicators like DMS and TBF. With low pressure boiling in the modern application, very high product quality standards were achieved. At the same time evaporation figures were reduced to 4.5 to 5%. This means a high saving of primary energy during the boiling process. New designs of internal boilers were developed to allow such technological results. The poster will incorporate the latest results and experience from recent installations, showing that this proven technology provides superior product quality.
Poster No. 13
Selective Recovery of Flavor Compounds from Fermenter Byproduct Carbon Dioxide Gas by Adsorption
Gil. W. Sanchez, Senior Research Engineer, Miller Brewing Company, Milwaukee, Wi 53201-0482
Carbon dioxide gas produced from beer fermentation contains an array of volatile byproduct compounds. Some of these compounds are pleasantly aromatic, such as longer chain-length alcohols and esters. However, fermentation byproduct gas streams also contain unpleasant compounds such as sulfides. Adsorption technology can be used to selectively recover the higher molecular weight alcohols, esters and hop components from fermenter carbon dioxide without adsorbing sulfides. These adsorbed components can then be recovered from the adsorbent with ethanol to produce a flavor concentrate useful for product enhancement This paper summarizes results from testing an adsorption column pilot skid on flavor recovery from fermenter carbon dioxide gas, the effect of process variables such as temperature and timing, and the impact of the flavor concentrate on product enhancement
Poster No. 14
The Application of a Densitometer for Improving Wort Consistency in a Small Brewery Operation
Sara Hale, Quality Manager, The Saint Louis Brewery, Inc., Schlafly Beers, St Louis, MO 63103 USA
Co-authors: James Ottolini ,Chief Engineer, The Saint Louis Brewery, Inc; Stephen Hale Chief Brewer, The Saint Louis Brewery, Inc.
Although densitometers are usually used only in large-scale breweries, small breweries can also utilize the information for improving wort extract, quality and consistency. Microbrewers generally have little control in the monitoring and extract of the wort during collection, and the densitometer offers a vast improvement over current methods available.
Poster No. 15
A Novel Stabilization of Beer
Mustafa Rehmanji, Group Leader, Beverage Products, International Specialty Products,
Wayne, NJ 07470 USA
Co-authors: Chandra Gopal, Technical Specialist, International Specialty Products; Andrew Mola, Staff Chemist, International Specialty Products
Stabilisation is an important stage in the production of beer, where an attractive appearance and flavour are considered key quality determinants. The methods adopted to achieve good colloidal stability have changed over time, reflecting both advances in brewing technology and a requirement to reduce production costs. Whilst current procedures usually concentrate on additions after fermentation - e.g. on transfer to maturation, or at filtration - little has recently been reported on colloidal stabilisation earlier in the brewing process. This paper describes a novel composite of carrageenan and micronized PVPP for use in beer stabilisation. A procedure for stabilizing beer in the brewhouse is developed which can be adopted to simplify downstream processing and reduce cost. This could be adopted by smaller breweries or larger breweries or breweries in developing markets, to achieve good colloidal stability. Elsewhere, it could provide an additional mechanism to chillproof 'difficult' beers in challenging envir onments.
The benefits of this composite will be discussed and will include the following i) improved compaction of whirlpool trub resulting in an increase in wort yield ii) carrageenan/micronized PVPP treated wort fermented better in terms of the drop in gravity as a function of fermentation time iii) improved filtration iv) improved beer haze and colloidal stability v) improved yeast vitality and crop. Some of the advantages of this approach include a single addition of the stabilizer for complete stabilization of the beer requiring no specialized dedicated equipment for dosing the stabilizer in the beer.
Poster No. 16
Identification, Cause, and Prevention of Musty Off-Flavours in Beer
Chantelle McRoberts, Scientist, Labatt Brewing Company Ltd., London, ON N6A 4M3 CAN
Co-authors: Michael J. McGarrity, Principal Scientist, Labatt Brewing Company Ltd.; Michael Fitzpatrick, Quality Technical Manager, Oland Brewing Company Ltd.
Musty off-flavours in beer can result from contamination with geosmin, 2- methylisoborneol, 2-isopropyl-methoxypyrazine, 2-isobutylmethoxypyrazine,2,3,6-trichloroanisole, or 2,4,6-trichloroanisole, alone or in combination. These malodorants can be introduced via source water, raw materials, or alternatively, may be generated within the brewery. In response to a brewery's sporadic musty problems, a study was undertaken to identify and eliminate the source(s) of musty off-flavours. A literature review of musty off-flavours, beyond the context of beer and water, was undertaken. In order to assess the plausibility of various vectors, sensory thresholds for the musty compounds were determined in beer. Remediation measures included improved practices pertaining to carbon filtration of source water, CIP procedures, packaging conditions, raw material storage, as well as physical upgrades to the brewery ventilation and pasteurization systems. A monitoring program, involving sensory and instrumental analysis, via a recently described method (ASBC, Victoria, June 2001), was implemented for th e brewery. As a result of these efforts, the problem appears to have been corrected. The resulting literature review and practical learnings, as well as threshold values, will be shared.
Poster No. 17
Determination of the Sources of Contamination Using a RAPD-PCR Method
Kazuhisa Yahata, Asahi Brewery Ltd., Hakata Brewery, Fukuoka-Shi, Fukuoka 816-0095 Japan
The RAP D-PCR method has been reported as an effective means of identifying the source of bacterial contamination and has been successfully applied to various cases, including those which involved pathogenic E. coli. This technique has also attracted wide acceptance due to the advantages in speed, accuracy and cost. In this study, we evaluated the applicability of the RAPD-PCR method in the brewery. The following four sample groups, from which bacteria were detected, were analyzed to identify a possible source of contamination: (a) beer products and work-in-process products, (b) operators working in brewery, )c) brewery environment (water splashes and air, etc.), and (d) process equipment and facilities. Based on the similarities of the RAPO profiles obtained from nonspoilage bacteria, Staphylococcus spp. found in finished beer and other sources, various contamination control measures were implemented. As a result an 87% reduction in detection rate of bacteria was achieved, compared with that of the previous year.
Poster No. 18
Electron Paramagnetic Resonance (EPR) Profiling for Potential Flavor stability Improvements in Beer
Robert T. Foster II, Research Associate, Coors Brewing Company, Golden, CO 80401 USA
Co-authors: Hugo Patina, Vice-President of Quality, Research and, Development, Coors Brewing Company; David R Barr, EPR Applications Scientist Bruker Instruments, Inc.
The Electron Paramagnetic Resonance (EPR) technology may benefit the brewer in a very practical way. This report, shows the results of several collaborative studies between Coors Brewing Company and the Applications Laboratory at Bruker Instruments, Inc. EPR is a form of magnetic resonance spectroscopy that detects unpaired (or 'free'), electrons in various samples (e.g. transition metals or free radicals). The technology is particularly useful because it, provides unambiguous detection of free radicals. In these studies a spin trap step stabilized the short-lived free radicals that formed during the forced oxidation of various beer samples.
These stabilized radical adducts were then, quantified in a "signature" EPR spectrum with the instrument Several spectra overtime produced an EPR intensity profile with a characteristic "lag" phase type graph. This initial "lag time" period in minutes is representative of the beer's resistance to oxidation. Through collaborative studies using packaged test and control beers, we see a dramatic difference in the lag time between control and high iron and high copper beers. We have also seen large lag time differences between beers bottled with normal versus oxygen scavenging crowns. Differences in lag time have been observed from different cellaring practices. The EPR "lag time" measurement can be used to identify high oxidation or metal pick-up periods within a process or plant. The relevance of these differences, however, needs to be assessed on a case-by-case basis.
Poster No. 19
European Brewing Congress Presentation
Poster No. 20
European Brewing Congress Presentation
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|Publication:||Modern Brewery Age|
|Date:||Sep 10, 2001|
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