Role of Riboflavin in Beer Flavor Instability:  Determination of Levels of Riboflavin and Its Origin in Beer by Fluorometric Apoprotein Titration

Abstract

A method for the quantitative determination of riboflavin levels in beer was developed. The method is based on the quenching of riboflavin fluorescence, which occurs when riboflavin binds to the aporiboflavin-binding protein from egg white. The method does not require any pretreatment of the beer before analysis, other than dilution, and proved to be simple, reliable, and sensitive. The lowest concentration that could be detected was approximately 10 nM riboflavin. The possible interference of flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD) with the determination of the riboflavin content of beer was excluded, because beer contains only a very small amount of FAD (0.03 microM) and no FMN. The riboflavin levels of the types and brands of beer investigated were in the range of 0.5-1.0 microM. The origin of the riboflavin in beer proved to be the malt. Hop and yeast hardly contributed to the riboflavin content of beer. Besides its use in the determination of riboflavin levels, the aporiboflavin-binding protein also provides a way to remove riboflavin from beer, which reduces the light sensitivity and the related lightstruck off-flavor formation in beer.

The APSES protein Sok2 is a positive regulator of sporulation in Ashbya gossypii

“…Each sample was divided in six aliquots of 50 μl. Four of the aliquots were spiked with 0, 10, 20 or 30 μl of a defined riboflavin stock solution to generate a calibration curve that was used to calculate the riboflavin concentration (Duyvis et al ., ). The remaining two aliquots were quenched with 10 μl of riboflavin binding protein (apo‐RfBP: 5 mg/ml) to obtain the background fluorescence intensity in each sample.…”

Light-induced quality changes in food and beverages

“…In 1963, Kuroiwa and co-workers put forward the fi rst simple theory to explain the formation of light-struck fl avour in beer (Kuroiwa et al, 1963). It was suggested that ribofl avin, which is naturally present in beer (at concentrations of a few hundreds of micrograms per litre) (Andrés-Lacueva et al, 1998;Duyvis et al, 2002) and shows a strong absorption around 375 nm and in the blue part of the visible spectrum around 445 nm, was acting as a photosensitizer, by transferring energy to isohumulones, thus provoking disintegration of the α-hydroxyketone moiety with formation of a 4-methylpent-3-enoyl radical (Fig. 5.12).…”

Smart Aptamer and Protein Functionalized Poly(N-isopropyl acrylamide) Materials for Selective Extraction of Riboflavin in Beer

“…15 Accordingly, the concentration of riboflavin in beer is a major factor for assessing flavor stability. 16,17 Riboflavin removal has been proposed as a strategy for controlling sunstruck flavor formation. 18 Manesiotis et al reported a kind of water-compatible imprinted polymers for selective depletion of riboflavin from beverages.…”