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Juste A.,Scientia Terrae Research Institute | Juste A.,Leuven Food Science and Nutrition Research Center oe | Malfliet S.,Leuven Food Science and Nutrition Research Center oe | Malfliet S.,Laboratory of Enzyme | And 10 more authors.
BrewingScience | Year: 2011

Malt is an important industrial product with a huge market outlet. The diverse microbial communities naturally colonizing barley grains greatly influence malt quality and subsequently other products in the malt value chain, in particular beer. In this manuscript, an overview is given of current knowledge of barley and malt-derived microorganisms and their impact on malt properties. In addition, emphasis is put on strategies to enhance the malting process, including the use of starter cultures and the management of endogenous microflora. Molecular studies on microbial community composition and function throughout the process will contribute to efficient implementation of these strategies, ultimately leading to more efficient wort production and enhanced beer flavour quality and stability. More specifically, these studies may lead to the discovery of novel, industrially important microbial strains or enzymes.

Van Durme J.,Catholic University of Leuven | Goiris K.,Laboratory of Enzyme | De Winne A.,Catholic University of Leuven | De Cooman L.,Laboratory of Enzyme | Muylaert K.,Catholic University of Leuven
Journal of Agricultural and Food Chemistry | Year: 2013

Due to their high content of polyunsaturated fatty acids, antioxidants, and proteins, microalgae hold a lot of potential for nutritional applications. When microalgae are integrated into foodstuffs, the aroma is an important aspect to consider. In this study the aroma properties of microalgae were studied by correlating data on the volatile composition with sensory evaluations. Four species of marine microalgae (Botryococcus braunii, Rhodomonas, Tetraselmis species, and Nannochloropsis oculata) and one fresh water microalga (Chlorella vulgaris) were investigated. Multivariate data processing revealed that microalgal samples having a seafood-like odor character contain high levels of sulfuric compounds (dimethyl disulfide, dimethyl trisulfide, and methional), diketones, α-ionone, and β-ionone. Fresh green, fruity flavors were linked with typical aldehydes such as 2,4-alkadienals and 2,4,6-alkatrienals. The presence of these compounds in fresh microalga pastes is explained by aroma formation mechanisms such as enzymatic lipid oxidation, enzymatic and chemical degradation of dimethylsulfoniopropionate (generating dimethyl sulfide), phenylalanine (generating benzaldehyde), and carotenoids (generating ionones). © 2013 American Chemical Society.

Goiris K.,Laboratory of Enzyme | Jaskula-Goiris B.,Laboratory of Enzyme | Syryn E.,Laboratory of Enzyme | Van Opstaele F.,Laboratory of Enzyme | And 3 more authors.
Journal of the American Society of Brewing Chemists | Year: 2014

The influence of hop polyphenols on the organoleptic properties of beer remains a matter of debate. Therefore, in this article, the use of different hop polyphenol fractions in combination with varying hop essences is discussed in relation to beer sensory properties (bitterness, fullness, and astringency). Hop polyphenol extracts made from spent hops, obtained after CO2 extraction of hops, were evaluated in respect to their flavoring potential. Except for the proanthocyanidins, all polyphenolic preparations were highly flavor-active, with positive effects on mouthfeel. Furthermore, the novel hop polyphenol products offer great potential for innovative flavoring when combined with hop aroma essences. © 2014 American Society of Brewing Chemists, Inc.

Jaskula-Goiris B.,Laboratory of Enzyme | Goiris K.,Laboratory of Enzyme | Syryn E.,Laboratory of Enzyme | Van Opstaele F.,Laboratory of Enzyme | And 3 more authors.
Journal of the American Society of Brewing Chemists | Year: 2014

In modern brewing technology, advanced hop products derived from pure resin extract are increasingly used in order to obtain a more consistent hoppy character in existing brands and to develop new beers with innovative flavor profiles. However, currently available advanced hop products such as (reduced) iso-α-acid extracts and hop oils do not contain hop polyphenols that are generally considered as potent antioxidants and therefore could be important in view of preparing more flavor-stable beers. We have shown previously that the addition of polyphenolic extracts from spent hops cv. Saaz (either at the onset of maturation or to the finished beer) improves the sensory properties of the resulting beers. In this article, the use of these hop polyphenol enriched extracts at specific points during the beer production process is discussed from the perspective of beer flavor quality and stability. Results from pilot scale brewing trials show that the addition of hop polyphenols enhances the mouthfeel, the reducing power, and the flavor stability of beer. © 2014 American Society of Brewing Chemists, Inc.

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