Part I: the influence of serial repitching ofSaccharomyces pastorianuson the uptake dynamics of metal ions and fermentable carbohydrates during the fermentation of barley and gluten-free buckwheat and quinoa wort

Abstract

Recently, research has been focusing on the use of alternative raw materials for brewing purposes and gluten-free beer-like beverages from malted buckwheat and quinoa are of commercial interest. A common commercial process involves the serial repitching of the yeast biomass, but this has not been described using buckwheat and quinoa wort fermentations. Our research studies (Parts I-III) explored the serial repitching of the yeast strain Saccharomyces pastorianus TUM 34/70 on the composition of a barley, buckwheat and quinoa fermentation medium. The present paper focuses on the fermentation performance and the uptake dynamics of metal ions and fermentable carbohydrates. Both pseudocereals showed high variations in all of the attributes examined during successive fermentations. In buckwheat the differences between successive fermentations were similar to those observed with barley, whereas differences in quinoa varied quite significantly from those observed with barley and showed a directional trend, suggesting a general weakening of the yeast from the sixth successive fermentation onward. In particular, the assimilation of the fermentable carbohydrates lessened and metal ion uptake appeared poorly controlled. It was concluded that buckwheat showed good potential for serial repitching of S. pastorianus TUM 34/70, whereas serial repitching of a quinoa wort appeared to be limited to five or six fermentations.

Part III: the influence of serial repitching ofSaccharomyces pastorianuson the production dynamics of some important aroma compounds during the fermentation of barley and gluten-free buckwheat and quinoa wort

“…In this study, the main focus was given to the production dynamics of the selected VCs as a function of successive fermentation and raw material type, that is, barley, buckwheat and quinoa. Because the attenuation time, that is, the last day when a daily change in the extract content was ≥0.1%, was raw material‐ and successive fermentation‐dependent (Table in Part I) , the time axis was relativized throughout this entire paper. In order to quantitatively support the visual observations, some quantitative statistical concepts were used.…”

Part II: the influence of the serial repitching ofSaccharomyces pastorianuson the uptake dynamics of amino acids during the fermentation of barley and gluten-free buckwheat and quinoa wort

“…In this study, the main focus was given to the uptake dynamics as a function of successive fermentation and raw material type, that is, barley (Figs ), buckwheat (Figs ) and quinoa (Figs ). Because the attenuation time, that is, the last day when a daily change in the extract content was ≥0.1%, was raw material‐ and successive fermentation‐dependent (Table 1 in Part I) , the time axis was relativized throughout the entire paper. Similarly, the dependent attribute was expressed as a percentage of its content in wort because wort from two (buckwheat and quinoa) or four (barley) different brews was used and because uptake profiles based on relative values enabled us to compare different AAs from different sources with each other.…”

Suitability of unmalted quinoa for beer production

“…Indeed, the Food and Agriculture Organization of the United Nations lists quinoa as 1 of 11 cereals / pseudocereals of interest to brewers . Being a gluten‐free raw material, quinoa has been investigated for brewing gluten‐free beer . However, quinoa malt has a very low hydrolytic enzyme content in comparison to barley malt, which requires the use of exogenous enzymes .…”

“…7 Being a gluten-free raw material, quinoa has been investigated for brewing gluten-free beer. [8][9][10][11][12][13] However, quinoa malt has a very low hydrolytic enzyme content in comparison to barley malt, which requires the use of exogenous enzymes. 14 Moreover, to avoid unpleasant bitterness, the outer seed coat of quinoa containing saponins must be removed.…”

“…Although there have been reports of quinoa malt being used to produce gluten-free beer, [8][9][10][11][12][13] no detailed studies have been conducted on the processability of unmalted quinoa. This www.soci.org E Kordialik-Bogacka et al…”