getpdf  NLM-PubMed-Logo  doi: 10.17113/ftb. 

Technological Development of Brewing in Domestic Refrigerator Using Freeze-Dried Raw Materials

Angelika-Ioanna Giallelismall orcid_display_4pp, Vassilios Ganatsiossmall orcid_display_4pp, Antonia Terpousmall orcid_display_4pp, Maria Kanellaki*small orcid_display_4pp, Argyro Bekatorousmall orcid_display_4pp, Athanasios A. Koutinassmall orcid_display_4pp and Dimitra Dimitrellousmall orcid_display_4pp

Department of Chemistry, Food Biotechnology Group, University of Patras, Patras, Greece

Article history:
Received: July 22, 2016
Accepted: May 10, 2017

Key words:
brewing, low-temperature fermentation, novel technology, immobilized cells, freeze-drying, tubular cellulose

Development of a novel directly marketable beer brewed at low temperature in a domestic refrigerator combined with yeast immobilization technology is presented in this study. Separately, freeze-dried wort and immobilized cells of the cryotolerant yeast strain Saccharomyces cerevisiae AXAZ-1 on tubular cellulose were used in low-temperature fermentation (2, 5 and 7 °C). The positive effect of tubular cellulose during low-temperature brewing was examined, revealing that freeze-dried immobilized yeast cells on tubular cellulose significantly reduced the fermentation rates in contrast to freeze-dried free cells, although they are recommended for home-made beer production. Immobilization also enhanced the yeast resistance at low-temperature fermentation, reducing the minimum brewing temperature value from 5 to 2 °C. In the case of high-quality beer production, the effect of temperature and initial sugar concentration on the fermentation kinetics were assessed. Sensory enrichment of the produced beer was confirmed by the analysis of the final products, revealing a low diacetyl concentration, together with improved polyphenol content, aroma profile and clarity. The proposed process for beer production in a domestic refrigerator can easily be commercialized and applied by dissolving the content of two separate packages in tap water; one package containing dried wort and the other dried immobilized cells on tubular cellulose suspended in tap water.

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