Quantification of Beer Based on the Original Freshness, Freshness Scale

By Osamu Ogane, F. Yokoyama and T. Hirano Kirin Brewery Co., Ltd., Yokohama, Japan. This poster was originally presented at the MBAA 112th Anniversary Convention, Keystone, Colorado, 1999.

Abstract
A method was develuped to quantify beer freshness based on the original freshness scale. At the completion of beer brewing, the fresh- ness value is set at 100%. This value then decreases from this point on. The reduction in the freshness value is expressed as a function of time and storage temperature, as shown below: Freshness value (%)= 100 * EXP (- JK * dt) = 100 * Xt/Xo In this formula, K= the degree of deterioration in beer quality over a set: period of time Clunk/day), t= number of storage days, and Xt, and XO= the experimentally determined values for freshness. It was attempted to find a correlation between the freshness value and sensory evaluation for beers obtained from different breweries, brewed at different: times, or from different lots within the same brew- ery. It was found that when the same type of beer was compared, it was possible to determine the beer freshness quantitatively, even if the brewery and the brewing period differed.
Keywords: Beer Freshness Scale, Beer Staling Mechanisms, Freshness Value  

Sintesis
Un metodo fue desarrollado para cuantificar la frescura de la cerveza basado en la escala de frescura original. Al terminar la elab- oracion de la cerveza el valor de Ia frescura se pone al 100%. Asi, este valor disminuye a partir de este punto. La reduccion del valor de frescura se expresa coma una funcion de tiernpo y de temperatura de almacenamientu, coma se muestra a continua&k: Valor de frescura (96) = 100. EXP(- JK m dt) = Xt/Xo En esta formula, K = el gradu de deterioro en la calidad de la cerveza en un periodo de tiempo establecidu (1 unidad/dia), t = numero de dias de almacenamiento y Xt y Xo = los valores de fres- cura determinados experimentalmente. Se intento encontrar una correlacion entre los valores de frescura y la evaluacidn sensorial de cervezas obtenidas de diferentes cerve- cerias, elaboradas a diferentes tiempos o de diferente lote de una misma cerveceria. Se encontro que cuando se comparaba el mismo tipo de cerveza, era posible el determinar la frescura de la cerveza cuantitativamente, aun cuando la cerveceria y el periodo de elabo- racion eran diferentes.