Technical Session 21: Spent Grains Session
Julia Steiner, TU München, Freising, Germany
Co-author(s): Martin Zarnkow and Thomas Becker, TU München, Freising, Germany
ABSTRACT: Seventy-five percent of all organic residues
originating from brewing are spent grains, which constitute the most
important and energy-rich by-product from the brewing process. Refining
spent grains rich in beneficial ingredients is of great interest for
valuable preservation of human nutrition. Although they are a remnant,
they still contain high-quality dietary fibers (i.e., arabinoxylan and
beta-glucan), which are difficult to utilize due to their structure and
the preceding process steps. Therefore, the use of hydrothermal cleavage
was investigated, and possible fields of application for beverage
technology have been developed. It was the purpose of this study to
break down the complex insoluble polysaccharides to educe and transfer
the cleavage products to a soluble state in order to add them to new
beverages as an ingredient with health beneficial attributes. With
regard to an increase in health consciousness and the shift in
consumption habits toward soft drinks, the brewing industry faces new
opportunities and challenges. Based on the current trend, beverages rich
in dietary fiber have emerged. These successful innovations receive
distinctive appreciation and sustained acceptance by consumers. In
particular, beta-glucan offers a comprehensive potential for functional
beverages, due to its origin in natural raw materials and its
scientifically proven positive and health-promoting effects. This paper
presents an innovative way to produce novel fiber-based drinks using
lactic acid fermentation. Dietary fibers are purified using hydrothermal
cleavage, and subsequently the hydrolysates are fermented by selected
strains. The resulting fermentation products are mixed with different
beverages and carbonated, resulting in well-balanced refreshment.
Laboratory-scale trials have been carried out to select the best process
parameters in order to gain maximum dietary fiber content. The
evaluation of the novel utilization technology is based on analytical
attributes measured using HPLC. To ensure the hydrothermal reaction
conditions and to determine the influence of temperature and residence
time, the cleavage process was conducted at temperatures ranging from
170 to 230°C and varying residence times. Consequential rising
decomposition products such as hydroxymethylfurfural and furfural, which
may not exceed certain concentrations due to possible health risks, are
undesired. By contrast, a preferably high proportion of arabinoxylan
and beta-glucan is definitely desired. Suitable approaches to and
treatment intensities for an improved yield of dietary fibers and a low
yield of undesired substances (under the critical limit) are shown in
this research. Particular attention is directed toward functional
ingredients, with a focus on beta-glucan, which was shown to be stable
in the produced beverages. With an adequate concentration of
beta-glucan, specific application examples could be offered as a reward
for functional food with an additional benefit by the EFSA and FDA.
Julia
Steiner was born in 1984 in Munich, Germany. In 2009 she graduated from
the Technische Universität München as with a Dipl.-Ing. degree in
technology and biotechnology of food. Since 2010 she has been working as
a Ph.D. student at the Institute of Brewing and Beverage Technology in
Weihenstephan, TU München. Julia is investigating complex spent grain
components, pursuing the aim to preserve this brewery by-product, which
is valuable for human nutrition. The intent of this research project is
the transfer of insoluble dietary fiber fractions into a soluble state
in order to add them to novel beverages as an ingredient with health
benefits.
VIEW PRESENTATION 73