The device for the controlled illumination of beer in the closed bottle to induce its light deterioration and to evaluate the proneness of beer to this damage type
Abstract
The device illuminates beer in a closed bottle for a defined period of time with light of a suitable defined spectral composition and defined intensity. Simultaneously the device allows to record changes in optical parameters of beer (caused by light) before exposure and after exposure, or during exposure or at intervals between individual partial exposures.
Optical parameters that are affected by exposure are either transmittance in the region of 445 +/- 25 nm or luminescence with an emission length of 520 +/- 25 nm excited in the region of 445 +/- 25 nm. The magnitude of the changes in these parameters after a defined illumination can also be used to infer the susceptibility of the sensory properties of beer in a given bottle to the damage caused by light exposure.
The apparatus consist of a cylindrical housing in which the beer bottle to be examined is placed in the centre. The self-adhesive LED strips are wound spirally on the inside of the cylinder.
The LEDs are selected so that the light emitted by them contains a spectral component between 400-500 nm - they are broadband LEDs with a central wavelength of 450 +/- 10 nm. The light sources are powered by an excitation electronic source.
Constant light flux exposure is controlled for a defined time interval. A probing light emitter and an optical receiver are disposed opposite each other on the axis passing through the centre of the bottle.
The transmitting LED emits light at a wavelength of 445 +/- 25 nm, which is transformed by lens to a collimated beam. This light beam, after passing through the beer bottle, is focused on the optical receiver whose output signal is processed in the electronic block.
In order to avoid the possible heating of the beer in the bottle by the heat released from the light sources, the bottom of the cylindrical housing consists of a metal grid below which is the fan generating a stream of air cooling the bottle.