Program Book - Master Brewers Association of the Americas

P-193
Sensory comparison of the same lager beer stabilized
through two different techniques: Pasteurization and bottle
conditioning
ANDREA PAVSLER (1), Stefano Buaitti (1), Matteo Milan (1)
(1) Department of Food Science, University of Udine, Udine, Italy
The shelf life of beer is one of the major concern for brewers and,
as is known, it is obtained through the pasteurization process.
Nevertheless to preserve the “handmade” characteristics of a
product, the shelf-life can be improved by bottle conditioning
without heat treatment of beer. Industrial lager beers, generally
characterized by low alcohol (between 4 and 5% by vol.) and extract
content, after filtration, are pasteurized to obtain biological
stability. Bottle conditioning is a technique generally used to
produce top fermentation beers with an alcohol content higher
than 6% by volume. To evaluate the effect of bottle conditioning on
sensory quality of a lager, a bottom fermentation beer (pasteurized)
has been compared to the same beer bottle conditioned with
different yeasts. A pasteurized lager (sample P) and five bottle
conditioned lagers (not pasteurized) with four yeast strains were
tasted after 10 months. As is known after this time, sometimes
even earlier, beers can show staling problems affecting shelf life.
All tasted beers came from the same starting batch (SB) of filtered
and not pasteurized lager; sample P was obtained from SB after
pasteurization processing (21 PU, Pasteurization Units) while
bottle conditioned beers were added with sucrose to have a final
carbon dioxide content of 4.5 g/L and an amount of yeast to obtain a
viability equal to 5 × 10 4 CFU/mL. All samples were stored at 20°C.
The samples of bottle conditioned beer were kept at 23°C for the
first month to allow the yeast to ferment the added sugar. A sensory
test of all beers was carried out by a trained panel of 13 assessors;
each sample were randomly tasted at the 10th month, and aroma
and taste were evaluated considering several aspects using a rating
test. Results showed that bottle conditioned beers were appreciated
as much as pasteurized ones and, some of them, even more. Possibly
due to its reducing power and oxygen scavenger effect, yeast acts
as a protection against the off-flavor development mainly related
to staling taste. Results showed that bottle conditioning can be an
interesting and valid system even for bottom fermentation beer in
order to obtain a stable and distinct product according the yeast
strain used.
Andrea Pavsler received a degree in food science from the University
of Udine, Italy, in 2003. In 2004 he has started a Ph.D. student
course in food science, focusing on studies in brewing science and
technology. Since then he has worked at the Department of Food
Science of the same university. He joined the Thornbridge Brewery in
Sheffield (United Kingdom) from February to May 2008 to improve
his knowledge in management and brewing technology.
P-194
Development and practical implementation of competencybased
standards for professional beer tasters
WILLIAM SIMPSON (1), Ronald Nixdorf (1), Boris Gadzov (1),
Javier Gomez-Lopez (1), Evelyne Canterranne (1)
(1) FlavorActiV Limited, Chinnor, United Kingdom
Objective evaluation of flavor is one of the most critical quality
assurance tests carried out on beer in final pack and in-process.
The reliability of such tests depends on the competence of the
assessors and the number of assessors used to evaluate each
sample. As with any high level skill, the aptitude and performance
of the people carrying out the tests can vary greatly. Historically,
beer tasters have been encouraged to develop their skills over a
period of many years, building up experience in day-to-day tasting
in the brewery. In some companies, however, an erroneous link
has developed between taster status—as indicated by job title or
number of years of service—and tasting ability. Unfortunately, taster
status is an unreliable indicator of taster performance. To help
address this issue and improve the skills of brewery tasters, we have
developed and tested competency-based approaches to taster skills
development and successfully applied them in partnership with a
large number of breweries. We have used web-based technologies
to collect information concerning the performance of about 4,000
professional beer tasters in more than 350 breweries over a period
of five years. Our results have substantial geographic coverage,
representing data from assessors in close to 100 countries.
We have also collected and analyzed information from several
hundred trainee tasters, acquired during intensive taster training
courses. Our studies have shown that competency-based skills
development programs provide an effective means of training
professional beer tasters. Selection and screening of assessors prior
to training, provided it is done in the right way, leads to a substantial
improvement in training outcomes. Tasters who can demonstrate a
high degree of competence in training and post-training testing also
perform well in routine taste tests. Those who perform less well in
training and post-training testing also perform less well in routine
taste tests.
Bill Simpson joined Scottish brewer Tennent Caledonian Breweries
in 1977 as a trainee microbiologist. Studying part-time he gained
a first-class honors degree in microbiology and a lot of brewery
experience before embarking on a 9-year program of research with
the Brewing Research Foundation (BRF) in England. During that
time he published extensively in areas such as brewery microbiology,
yeast, and flavor chemistry. He rose to the position of principal
scientist and head of fermentation before leaving BRF in 1995 to
start his own company, Cara Technology. Since then he has gone
on to start two other companies—FlavorActiV and Avesio Systems.
In addition to his on-going research in the areas of beer flavor
chemistry, sensory science, and yeast, Bill consults for a number of
international brewery groups, with particular emphasis on process
problem solving. He won the Institute of Brewing & Distilling (IBD)
Cambridge Prize for Brewing Research for his Ph.D. work on hop
bitter acids and beer spoilage bacteria in 1991 and has published
more than 100 scientific papers, books, and patents on brewing
technology. Bill is a Fellow of the IBD and a member of the ASBC
Journal Editorial Board.
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