A laboratory fermentation method to determine the influence of micro-nutrient levels on wort fermentability

MACLEOD, AARON - GÓMEZ, BLANCA - EDNEY, MICHAEL J.

Resumen:

Fermentability is an important malt quality parameter as it predicts potential beer production. The standard EBC method for measuring a malt's fermentability uses Congress wort, high pitching rates and continuous stirring to achieve results in 24 hours. Tests in our laboratory indicated a 100% maltose wort could be fermented to completion under such conditions suggesting micro nutrients, such as amino acids and minerals, are not required at such high pitching rates. The present study investigated reduced pitching rates and the use of adjunct, as a means of better determining the necessity of micro nutrients. Different levels of yeast and adjunct were compared using a 4-day fermentation period with density measurement every 24 hours. A pitching rate of 6 million cells/ml, versus 20 million in the standard method, a 60:40 ratio of Congress wort to maltose syrup (8 degrees Plato) along with a 24-hour fermentation period were found to best reflect differences in the supply of micro nutrients. A study of four malts with significant differences in quality showed that fermentable sugars were the only limiting factor to fermentability as measured with the standard EBC test. Only when the adjunct was used with the lower pitching rate did significant differences in FAN and become a limiting factor to fermentability. The modified method is now be used to study effects of individual amino acids and availability of minerals on fermentability.


Detalles Bibliográficos
2009
FERMENTACIÓN
LEVADURAS
MÉTODOS DE ENSAYO
MOSTO
NUTRICIÓN
Inglés
Laboratorio Tecnológico del Uruguay
Catálogo digital del LATU
https://catalogo.latu.org.uy/opac_css/index.php?lvl=notice_display&id=29148
Acceso abierto
CC BY-NC-ND
Resumen:
Sumario:Fermentability is an important malt quality parameter as it predicts potential beer production. The standard EBC method for measuring a malt's fermentability uses Congress wort, high pitching rates and continuous stirring to achieve results in 24 hours. Tests in our laboratory indicated a 100% maltose wort could be fermented to completion under such conditions suggesting micro nutrients, such as amino acids and minerals, are not required at such high pitching rates. The present study investigated reduced pitching rates and the use of adjunct, as a means of better determining the necessity of micro nutrients. Different levels of yeast and adjunct were compared using a 4-day fermentation period with density measurement every 24 hours. A pitching rate of 6 million cells/ml, versus 20 million in the standard method, a 60:40 ratio of Congress wort to maltose syrup (8 degrees Plato) along with a 24-hour fermentation period were found to best reflect differences in the supply of micro nutrients. A study of four malts with significant differences in quality showed that fermentable sugars were the only limiting factor to fermentability as measured with the standard EBC test. Only when the adjunct was used with the lower pitching rate did significant differences in FAN and become a limiting factor to fermentability. The modified method is now be used to study effects of individual amino acids and availability of minerals on fermentability.