6 research outputs found
The effect of yeast growth stages on the absorption of polyphenols
Colloidal stability of beer is one of the most critical challenges facing the brewing
industry. In brewing, stabilization agents are widely used to remove colloids such as proteins and
polyphenols. However, the removal efficiency of polyphenols depends on the yeast, which
adsorbs these compounds on its surface. The adsorption of polyphenols on the yeast surface is
associated with the zeta potential of the cell wall, which correlates with the mannan content in
them. The purpose of the study was to investigate the role of yeast strains in adsorption of
polyphenols (increasing colloidal stability of beer) and the correlation of this property with the
mannan content in the cell wall during the fermentation. Two S. cerevisiae strains were used in
this study, and the specific growth rate of yeast, the specific rate of change in the polyphenol
content and the mannan content were determined. The results of this study showed that the highest
mannan content in yeast was after 9 hours (the end of exponential growth phase). Its content was
10.97% by weight of dry matter in the yeast S. cerevisiae Californian Lager (M54), and 13.69%
in the yeast S. cerevisiae Belgian Wit (M21). The desorption of polyphenols was observed during
the period from 9 to 24 hours of fermentation, where an increase in the content of polyphenols in
the medium was observed. Based on these results, it is necessary to remove the yeast at the end
of the exponential growth phase to increase the colloidal stability of the beer
Comparison of the yeast Saccharomyces cerevisiae var. boulardii and top-fermenting brewing yeast strains during the fermentation of model nutrient media and beer wort
Received: June 27th, 2022 ; Accepted: September 18th, 2022 ; Published: October 17th, 2022 ; Correspondence: [email protected], the yeast Saccharomyces cerevisiae var. boulardii have attracted the
attention of Food Science researchers due to their unique properties, the main among which are
probiotics. Thus, research is conducted on the use of this yeast as a starter culture in the
technology of yogurt, fermented vegetables, fruit, vegetable juices, as well as beer. This paper is
aimed at studying Saccharomyces cerevisiae var. boulardii 's fermentation performance
compared to top-fermenting brewing yeast strains during fermentation of model nutrient media
and beer wort. Fermentation activity of the studied strains was assessed based on the character of
fermentation curves, as well as the values of the maximum substrate assimilation rate and
apparent degree of fermentation. Moreover, during the study, beer was produced using the yeast
Saccharomyces cerevisiae var. boulardii as a starter culture. According to the obtained results, it
can be concluded that Saccharomyces cerevisiae var. boulardii have less fermentation activity
compared to brewing strains. In turn, beer produced with Saccharomyces cerevisiae var.
boulardiisignificantly differed in physicochemical, microbiological, and organoleptic parameters
from the control sample obtained using the 047A brewing strain. Thus, it contained less ethanol
and secondary metabolites; however, the concentration of living cells was significantly higher,
which indicates a relatively high viability of the yeast Saccharomyces cerevisiae var. boulardii.
From an organoleptic point of view, final beer has a positive sensory profile. The aroma of the
product had a complex character: it included caramel, spicy, fruity and phenolic notes, as well as
smoked and wine elements; while honey was the dominant note of the taste
Synthesis and Antibacterial Activity of Chitin Tetrazole Derivatives
New tetrazole derivatives of natural chitin polymers of high, medium, and low molecular masses with high, medium, and low degrees of substitution were synthesized and tested in vitro for antibacterial activity. The obtained tetrazole derivatives were characterized by pronounced antibacterial activity in vitro against S. aureus and E. coli. The chitin derivative of medium molecular mass with a medium degree of substitution had the highest antibacterial activity among all obtained derivatives. The antibacterial activity of this derivative as measured by bacterial growth inhibition zones was comparable to those of the antibiotics ampicillin and gentamycin. Β© 2020, Springer Science+Business Media, LLC, part of Springer Nature
Novel non-toxic high efficient antibacterial azido chitosan derivatives with potential application in food coatings
In this work, we developed a simple method for the preparation of N-(3-azido-2-hydroxypropyl)chitosan. We compared the antibacterial activity of N-(3-azido-2-hydroxypropyl)chitosans and previously synthesized N-(2-azidoethyl)chitosans. N-(3-azido-2-hydroxypropyl)chitosans possess higher antibacterial effect which is comparable with that of ampicillin and gentamicin. The effect is due to azido pharmacophore βCH2βCH(OH)βCH2βN3 (for N-(3-azido-2-hydroxypropyl)chitosan) or βCH2βCH2βN3 (for N-(2-azidoethyl)chitosan) introduced in chitosan chain, since the corresponding organic azides NH2βCH2βCH2βN3 and NH2βCH2βCH2βN3 are characterized by high antibacterial activity. However, high antibacterial organic azides NH2βCH2βCH2βN3 and NH2βCH2βCH2βN3 are characterized by high toxicity. Their conjugation to the chitosan chain saves their antibacterial effect, but strongly diminishes their toxicity, and the toxicity of the resulting derivatives is comparable with that of the starting chitosan. These findings are of interest to food science, since novel effective food coatings can be developed on basis of prepared derivatives. Β© 201
Π‘ΠΈΠ½ΡΠ΅Π· ΠΈ Π°Π½ΡΠΈΠ±Π°ΠΊΡΠ΅ΡΠΈΠ°Π»ΡΠ½Π°Ρ Π°ΠΊΡΠΈΠ²Π½ΠΎΡΡΡ ΡΠ΅ΡΡΠ°Π·ΠΎΠ»ΡΠ½ΡΡ ΠΏΡΠΎΠΈΠ·Π²ΠΎΠ΄Π½ΡΡ Ρ ΠΈΡΠΈΠ½Π°
The present study is devoted to the synthesis and study of the antibacterial activity in vitro of new tetrazole derivatives of natural polymer chitin of high, medium and low molecular weights with high, medium and low degree of substitution. The results showed that the obtained tetrazole derivatives are characterized by pronounced antibacterial activity in vitro against both S. aureus and E. coli strains. Among all derivatives, the highest antibacterial activity is demonstrated by a tetrazole derivative of chitin of moderate molecular weight and moderate degree of substitution. The antibacterial activity of this derivative as measured by the zone of inhibition of bacterial growth is comparable to the antibacterial activity of reference antibiotics ampicillin and gentamicin.ΠΠ°ΡΡΠΎΡΡΠ΅Π΅ ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΠ΅ ΠΏΠΎΡΠ²ΡΡΠ΅Π½ΠΎ ΡΠΈΠ½ΡΠ΅Π·Ρ ΠΈ ΠΈΠ·ΡΡΠ΅Π½ΠΈΡ Π°Π½ΡΠΈΠ±Π°ΠΊΡΠ΅ΡΠΈΠ°Π»ΡΠ½ΠΎΠΉ Π°ΠΊΡΠΈΠ²Π½ΠΎΡΡΠΈ in vitro Π½ΠΎΠ²ΡΡ
ΡΠ΅ΡΡΠ°Π·ΠΎΠ»ΡΠ½ΡΡ
ΠΏΡΠΎΠΈΠ·Π²ΠΎΠ΄Π½ΡΡ
ΠΏΡΠΈΡΠΎΠ΄Π½ΠΎΠ³ΠΎ ΠΏΠΎΠ»ΠΈΠΌΠ΅ΡΠ° Ρ
ΠΈΡΠΈΠ½Π° Π²ΡΡΠΎΠΊΠΈΡ
, ΡΡΠ΅Π΄Π½ΠΈΡ
ΠΈ Π½ΠΈΠ·ΠΊΠΈΡ
ΠΌΠΎΠ»Π΅ΠΊΡΠ»ΡΡΠ½ΡΡ
ΠΌΠ°ΡΡ Ρ Π²ΡΡΠΎΠΊΠΈΠΌΠΈ, ΡΡΠ΅Π΄Π½ΠΈΠΌΠΈ ΠΈ Π½ΠΈΠ·ΠΊΠΈΠΌΠΈ ΡΡΠ΅ΠΏΠ΅Π½ΡΠΌΠΈ Π·Π°ΠΌΠ΅ΡΠ΅Π½ΠΈΡ. ΠΠΎΠ»ΡΡΠ΅Π½Π½ΡΠ΅ ΡΠ΅ΡΡΠ°Π·ΠΎΠ»ΡΠ½ΡΠ΅ ΠΏΡΠΎΠΈΠ·Π²ΠΎΠ΄Π½ΡΠ΅ Ρ
Π°ΡΠ°ΠΊΡΠ΅ΡΠΈΠ·ΡΡΡΡΡ Π²ΡΡΠ°ΠΆΠ΅Π½Π½ΠΎΠΉ Π°Π½ΡΠΈΠ±Π°ΠΊΡΠ΅ΡΠΈΠ°Π»ΡΠ½ΠΎΠΉ Π°ΠΊΡΠΈΠ²Π½ΠΎΡΡΡΡ in vitro Π² ΠΎΡΠ½ΠΎΡΠ΅Π½ΠΈΠΈ S. aureus ΠΈ E. coli. Π‘ΡΠ΅Π΄ΠΈ Π²ΡΠ΅Ρ
ΠΏΠΎΠ»ΡΡΠ΅Π½Π½ΡΡ
ΠΏΡΠΎΠΈΠ·Π²ΠΎΠ΄Π½ΡΡ
Π½Π°ΠΈΠ±ΠΎΠ»ΡΡΠ΅ΠΉ Π°Π½ΡΠΈΠ±Π°ΠΊΡΠ΅ΡΠΈΠ°Π»ΡΠ½ΠΎΠΉ Π°ΠΊΡΠΈΠ²Π½ΠΎΡΡΡΡ Ρ
Π°ΡΠ°ΠΊΡΠ΅ΡΠΈΠ·ΡΠ΅ΡΡΡ ΠΏΡΠΎΠΈΠ·Π²ΠΎΠ΄Π½ΠΎΠ΅ Ρ
ΠΈΡΠΈΠ½Π° ΡΡΠ΅Π΄Π½Π΅ΠΉ ΠΌΠΎΠ»Π΅ΠΊΡΠ»ΡΡΠ½ΠΎΠΉ ΠΌΠ°ΡΡΡ ΡΠΌΠ΅ΡΠ΅Π½Π½ΠΎΠΉ ΡΡΠ΅ΠΏΠ΅Π½ΠΈ Π·Π°ΠΌΠ΅ΡΠ΅Π½ΠΈΡ. Π£ΡΡΠ°Π½ΠΎΠ²Π»Π΅Π½Π½Π°Ρ ΠΏΠΎ Π·ΠΎΠ½Π΅ ΠΈΠ½Π³ΠΈΠ±ΠΈΡΠΎΠ²Π°Π½ΠΈΡ ΡΠΎΡΡΠ° Π±Π°ΠΊΡΠ΅ΡΠΈΠΉ Π°Π½ΡΠΈΠ±Π°ΠΊΡΠ΅ΡΠΈΠ°Π»ΡΠ½Π°Ρ Π°ΠΊΡΠΈΠ²Π½ΠΎΡΡΡ Π΄Π°Π½Π½ΠΎΠ³ΠΎ ΠΏΡΠΎΠΈΠ·Π²ΠΎΠ΄Π½ΠΎΠ³ΠΎ ΡΠΎΠΏΠΎΡΡΠ°Π²ΠΈΠΌΠ° Ρ Π°Π½ΡΠΈΠ±Π°ΠΊΡΠ΅ΡΠΈΠ°Π»ΡΠ½ΠΎΠΉ Π°ΠΊΡΠΈΠ²Π½ΠΎΡΡΡΡ Π°Π½ΡΠΈΠ±ΠΈΠΎΡΠΈΠΊΠΎΠ² Π°ΠΌΠΏΠΈΡΠΈΠ»Π»ΠΈΠ½Π° ΠΈ Π³Π΅Π½ΡΠ°ΠΌΠΈΡΠΈΠ½Π°