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CLEANSING CONTAMINATED PITCHING YEAST WITH NISIN
Author(s) -
Ogden K.
Publication year - 1987
Publication title -
journal of the institute of brewing
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.523
H-Index - 51
eISSN - 2050-0416
pISSN - 0046-9750
DOI - 10.1002/j.2050-0416.1987.tb04507.x
Subject(s) - nisin , yeast , fermentation , food science , bacteria , lactic acid , chemistry , ammonium , contamination , microbiology and biotechnology , biology , biochemistry , organic chemistry , ecology , genetics
The ability of solutions of nisin to cleanse pitching yeast of contaminating gram‐positive lactic bacteria (at levels of about 1% by cell numbers) was compared to that of three different acid‐washing procedures: ammonium persulphate, acidified ammonium persulphate or phosphoricacid. 1000 international units ml −1 of nisin killed all the cells of more sensitive bacterial strains in less than 30 minutes, equivalent to the killing ability of the acid‐washing procedures, and more than 99·9% of cells of a more resistant strain in 2 hours. Washing contaminated pitching yeast with nisin has several advantages over acid‐washing methods. It has no effect on yeast viability and vitality, and, in subsequent fermentations, the yeast shows unchanged flocculation characteristics and fermentative performance.