Direct detection of beer photodegradation in commercial bottles and introduction of a new Light-Struck Flavour Susceptibility Index

Abstract

Exposure of beer to light results in the formation of undesirable flavours or complete spoilage. Photo-damaged beerhas a specific, so-called skunky or light-struck flavour (LSF). The compound responsible for LSF is 3-methylbut-2-ene-1-thiol (MBT). Riboflavin (RF) plays a key role in the formation of MBT. It absorbs light in the blue part of thespectrum and transfers excitation energy to isohumulones. This process is accompanied by the decomposition of RF,which causes a decrease in the absorbance of the sample at 450 nm. The decomposition is directly related to theformation of LSF. In this study, the decrease in absorbance associated with the defined illumination of model and realbeer directly in commercial bottles was measured. The decrease in absorbance correlated with the decrease in RFconcentration and the formation of LSF detected by the sensory panel. The Light-Struck Flavour Susceptibility Indexwas introduced as a rate of the beer susceptibility to light degradation and the formation of LSF.

Characterization of packaging ability to protect beer from light degradation and introduction of a new Packaging Riboflavin Index

“…The measurement of changes in absorbance of the sample directly in the bottle was used to determine the light degradation degree of beer. The light degradation of beer is associated with the breakdown of riboflavin, which causes changes in absorbance at around 450 nm (Pozdrik, 2006;Gabriel et al, 2022). The decrease in absorbance corresponds to the loss of riboflavin due to its decomposition during the light degradation of beer.…”

“…Riboflavin has a significant absorption peak at the wavelength of 450 nm, RF decomposition is associated with a decrease in sample absorbance in this region. The LSFS index introduced in previous article (Gabriel et al, 2022) was used as a measure of beer degradation. The LSFS index was calculated as a linear coefficient of a straight line interpolated by AbsBlue values in the initial phase of the degradation.…”

“…However, light can pass through glass or plastic bottles to a certain extent and interact with the beer causing its sensory damage. The degree of damage is determined by the spectral composition of the incident light, the intensity of the light at the point of impact on the beer bottle and the spectral dependence of the transmittance of the packaging for potentially dangerous radiation (Gabriel et al, 2022).…”

“…Figure 3 illustrates the absorbance (AbsBlu) curves at 466 nm measured on COLORTURB as a function of illumination time. The LSFS index was calculated from the decrease in absorbance (Gabriel et al, 2022). Nevertheless, AbsBlue decrease in sample GB1, i.e.…”

The Role of Emergent Processing Technologies in Beer Production

“…Regarding beer's flavor, breweries fear an undesirable off-flavor that is typically referred to as "light-struck flavor", which is mainly induced by 3-methyl-2-butene-1-thiol (MBT) and is easily detected in the flavor and aroma of beer when present above its flavor threshold [94]. The formation of such character, described as "skunky-like", is mostly triggered by the degradation of iso-α-acids present in beer by light (350-500 nm), and this has the negative consequence of limiting beer's shelf-life [95]. To investigate this issue, Milani et al (2015) investigated whether PEF technology has the potential to induce the "light-struck character" in nine beers (of different beer styles and alcoholic contents).…”