Specifying Amber Glass Color in Order to Protect Beer from Developing Lightstruck Character

By Vito Biundo Materials Scientist, Anheuser-Busch Companies, Inc., St. Louis, Missouri. This paper was originally presented at the MBAA 112th Anniversary Convention, Keystone, Colorado, 1999.

Abstract
Protecting beer from developing lightstruck character is one of the main performance criteria of the amber glass bottle. One of the tra-ditional methods of specifying amber glass color is by normalizing transmission values to a glass thickness of 1/8 inch. It has been found that these corrected transmission values do not correlate well with lightstruck character prevention. Tests were conducted in which lightstruck character prevention was analyzed versus actual and cor-rected transmission. Also evaluated were the wavelengths at which the amber color and lightstruck character protection should be tested. It was found that there is a better correlation of lightstruck character prevention with actual light transmission than there is with corrected light transmission. It is also suggested that to ensure that the beer is protected, light transmission values should be specified at 500nm and 550nm.
Keywords: glass, light, transmission, lightstruck  

Sintesis
El proteger a la cerveza contra el desarrollo de caracter�sticas de cerveza expuesta a la luz es uno de los principales criterios de desem-pe�o de la botella de vidrio �mbar. Uno de los m�todos tradicionales para especificar el color del vidrio �mbar es mediante la normal-izaci�n de valores de transmisi�n a un grosor de vidrio de 1/8 de pul-gada. Se ha descubierto que estos valores de transmisi�n corregidos no se correlacionan bien con la prevenci�n de caracter�sticas de cerveza expuesta a la luz. Se condujeron pruebas en donde la pre-venci�n de caracter�sticas de exposici�n a la luz fue analizada con la transmisi�n actual y corregida. Tambi�n se evaluaron las longitudes de onda en las cuales el color �mbar y la protecci�n de caracter�sti-cas de exposici�n a la luz deben ponerse a prueba. Se descubri� que hay una mejor correlaci�n de la prevenci�n de caracter�sticas de exposici�n a la luz con la transmisi�n de luz actual que con la trans-misi�n de luz corregida. Se ha sugerido tambi�n que para asegurar que la cerveza est� protegida, los valores de transmisi�n de luz deben especificarse a 500nm y 550nm.