Accumulation and Release of Metal Ions by Brewer's Yeast During Successive Fermentations

Abstract

J. Inst. Brew. 115(1), 78-83, 2009Magnesium, zinc and calcium are the elements that are involved in the regulation of metabolic activity of yeast and/or other processes such as flocculation and cell division. The requirements for specific ions may be subject to changes in successive fermentations performed by the same biomass. The aim of this work was to analyze the changes in calcium, magnesium and zinc concentration in malt broth (9°P) and in the yeast over four successive fermentations. For all ionic species analysed, the qualitative uptake and release patterns observed during subsequent fermentations were similar. In the lag phase of the fermentation, yeast cells accumulated the metal ions under investigation, in order to liberate them later to an extent that depended on the specific metal and fermentation number. Some differences were noted when qualitative comparison of these processes was performed. During the first fermentation with the yeast culture, the maximum content of each ion in the yeast biomass was twoto threefold higher than in the subsequent fermentations. Calcium, magnesium and zinc levels in the biomass did not exceed 1, 6 and 0.6 mg/g yeast dry weight respectively.

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

“…of our results it can be concluded that successive fermentations of barley wort influence only the temporary release of zinc during fermentation (i.e. the time and intensity of a peak value) and not the initial and overall uptake, the latter being in discordance with other reports (18,19), most likely because of the low zinc concentration in our wort.…”

“…In all cases, this increase reached a peak value in the first half of the fermentation, whereas its relative value was higher in later fermentations. This marked release of zinc by yeast has been observed previously and it was causally related to a drop in pH during the fermentation process, as that drop decreases the apparent stability constant of the zinc metal ion binders . This occurrence was presumably more considerable the more times the yeast slurry was reused.…”

“…The trace metal ions explored in this study, that is, iron, copper, zinc and manganese, play a crucial role, being a part of haem‐proteins, cytochromes, redox pigments, enzyme cofactors, and others. Their relevance in the brewing process has been widely reviewed elsewhere , but for barley beer there are only a few reports regarding metal ion nutrition where the same yeast was used twice or more . The physiological status of the yeast and the uptake rate and dynamics of a particular metal ion are primarily dependent both on its concentration in the wort and on its bioavailability.…”

Chemical Composition of Sour Beer Resulting from Supplementation the Fermentation Medium with Magnesium and Zinc Ions

“…In the latter case (zinc supplemented samples), the increase in the magnesium ion in the beer after fermentation was much higher, reaching 50% (from 120 to 175 mg/L in both the 0.4 and 2 mg/L Zn 2+ supplementation trials). Similar trends were observed in study Poreda et al [43], which proved that increased content of zinc ions in wort can block the uptake of magnesium ions by the yeast. The current results show that in the case of L. brevis strain the uptake and release of magnesium ions is not affected by the zinc ion content.…”

Microencapsulation of Baker’s Yeast in Gellan Gum Beads Used in Repeated Cycles of Glucose Fermentation

“…However, the metal ions have a significant impact on important parameters, including the conversion rate of sugar into ethanol, the final yield in ethanol, the growing and multiplying yeast, the cell viability, the stressors, and the yeast flocculation behavior [39,40].…”