Description:
The derivatization of thiamin vitamers to their respective thiochrome by ferricyanide to facilitate fluorescence detection following separation by HPLC provides a powerful analytical tool. However the polyphenolic compounds in red wine readily interact with ferricyanide, reducing the effectiveness of ferricyanide oxidation in the derivatization of thiamin. We describe a method to facilitate the removal of polyphenolic compounds that interfere with the ferricyanide derivatization of thiamin. Polyvinylpolypyrrolidone afforded the total removal of phenolic compounds from red wines and allowed a spike recovery of thiamin vitamers (101% for thiamin; 104% for TMP; and 100% for TDP) in a wide range of red wines. This research found that Merlot styles of red wine contained the highest concentration of total thiamin (29.01 ng/mL) while Pinot Noir wines contained the lowest total concentration (8.27 ng/mL).
Description:
The ability of added acetaldehyde to stimulate growth in ethanol-stressed Saccharomyces cerevisiae while grown on non-fermentable substrates (ethanol, glycerol) is reported. The addition of acetaldehyde to ethanol-stressed yeast grown on either ethanol or glycerol led to a significant decrease in lag time of 67 and 45%, respectively (p = 0.000) and an increase in the specific growth rate (0.008-0.038/h and 0.060-0.074/h, respectively). The stimulatory effect of acetaldehyde could be mimicked by the addition of propionaldehyde. Results, following metabolic tracing of the added stimulants, question the previously held notion that the acetaldehyde effect in S. cerevisiae is fully redox related.
Description:
Beer is a beverage that is produced in a multistage process, where some stages of that process are intentionally influenced by microorganisms, while at other stages of the production process microorganisms are actively discouraged. Most of the intentional microbial activity is facilitated by yeast; however bacteria also play an influential role in beer production. This paper will describe the beneficial role of bacteria in the beer production process (the Good), but will also pay due attention to the negative influences bacteria might have on the quality of beer as a commodity (the Bad), and the properties of beer that have given it the status of an inherently safe food for human consumption with regards to disease-causing bacteria (the Ugly). Copyright (C) 2013 The Institute of Brewing & Distilling
Description:
Thiamine and riboflavin vitamers are present in a wide range of foods including beer. They play critical roles in a variety of enzymatic complexes and can promote and maintain metabolism. Currently, the presence and role of these vitamers in the malting and brewing industry has not been widely explored. This research has investigated the effects of various malting and brewing processes on the final thiamine and riboflavin vitamer content of finished beer. In order to achieve this, a highly accurate and reproducible HPLC (spike recovery > 95 %; RSD < 5.0 %) method was developed that allowed the separation of thiamine diphosphate (TDP), thiamine monophosphate (TMP), thiamine, riboflavin 5-phosphate (FMN) and riboflavin in various sample matrices. This method was utilised to determine the vitamer content of various cereals and malts and it was found that malting vastly alters the thiamine content of malted barley, while it has minimal effect on riboflavin content. When malted barley is roasted, all vitamers are rapidly degraded. The mashing process releases the various vitamers into a solution and this release is dependent on temperature and enzymatic activity, while wort boiling significantly reduces the vitamer content of the wort. During fermentation, the thiamine content of wort is quickly utilised within the first six hours of standard fermentations and the uptake of this vitamin is not affected by increases in wort gravity. Meanwhile riboflavin is only poorly utilised during these fermentations. Post-fermentative additives, such as the addition of tannic acid and potassium metabisulphite, negatively affect the vitamin content of the final product while phosphorylated forms of these vitamins are greatly affected by the addition of many post-fermentative processing aids/additives. The presence of both thiamine and riboflavin can enhance the spoilage of beer by known brewery spoilage organisms, and the incorrect storage of bottle-conditioned beer can negatively affect the vitamin and organoleptic properties of the final product. These various steps involved in the production of beer greatly affect the final vitamin content, and this knowledge helps to explain the large variation in the thiamine and riboflavin vitamer content of a survey of 204 commercially available beers. This survey concluded that despite the large variations within particular styles of beer, lagers contain the least amount of thiamine compared to ales, stout/porters and wheat beers. However the average riboflavin content of the tested beers was statistically similar (p = 0.608) across all of the styles. This is due to the limited utilisation of this vitamin during fermentations.
Description:
Thiamine and riboflavin vitamers are present in a wide range of foods including beer. They play critical roles in a variety of enzymatic complexes and can promote and maintain metabolism. Currently, the presence and role of these vitamers in the malting and brewing industry has not been widely explored. This research has investigated the effects of various malting and brewing processes on the final thiamine and riboflavin vitamer content of finished beer. In order to achieve this, a highly accurate and reproducible HPLC (spike recovery > 95 %; RSD < 5.0 %) method was developed that allowed the separation of thiamine diphosphate (TDP), thiamine monophosphate (TMP), thiamine, riboflavin 5-phosphate (FMN) and riboflavin in various sample matrices. This method was utilised to determine the vitamer content of various cereals and malts and it was found that malting vastly alters the thiamine content of malted barley, while it has minimal effect on riboflavin content. When malted barley is roasted, all vitamers are rapidly degraded. The mashing process releases the various vitamers into a solution and this release is dependent on temperature and enzymatic activity, while wort boiling significantly reduces the vitamer content of the wort. During fermentation, the thiamine content of wort is quickly utilised within the first six hours of standard fermentations and the uptake of this vitamin is not affected by increases in wort gravity. Meanwhile riboflavin is only poorly utilised during these fermentations. Post-fermentative additives, such as the addition of tannic acid and potassium metabisulphite, negatively affect the vitamin content of the final product while phosphorylated forms of these vitamins are greatly affected by the addition of many post-fermentative processing aids/additives. The presence of both thiamine and riboflavin can enhance the spoilage of beer by known brewery spoilage organisms, and the incorrect storage of bottle-conditioned beer can negatively affect the vitamin and organoleptic properties of the final product. These various steps involved in the production of beer greatly affect the final vitamin content, and this knowledge helps to explain the large variation in the thiamine and riboflavin vitamer content of a survey of 204 commercially available beers. This survey concluded that despite the large variations within particular styles of beer, lagers contain the least amount of thiamine compared to ales, stout/porters and wheat beers. However the average riboflavin content of the tested beers was statistically similar (p = 0.608) across all of the styles. This is due to the limited utilisation of this vitamin during fermentations.
Description:
This research aimed to develop a simple and effective method for analyzing thiamin (B 1), riboflavin (B 2) and their respective vitamers by high performance liquid chromatography (HPLC) in fermented alcoholic beverages. The method developed here employs a phosphate buffer/methanol gradient elution on a single reverse phase column, coupled with independent fluorescent detection regimes. It also employs a precolumn derivatization to convert thiamin to thiochrome via an alkaline potassium ferricyanide solution. The method described here allowed a spike recovery of better than 97%, with a typical linear detection range (R 2 ≥ 0.9997) between ≥5 and ≥500
Description:
Wort production contains a number of processing steps that are aimed at the optimal extraction of nutrients from malt, including vitamins. This research revealed that the different wort production processing steps imposed different influences on the thiamine and riboflavin vitamer content of the final sweet wort. These vitamins play vital roles within yeast metabolism, where they act as enzyme cofactors. As such thiamine vitamers play a crucial role in many decarboxylating enzymes, while riboflavin vitamers play an integral role in energy production and redox maintenance. While mashing releases valuable starch into the liquor, both thiamine and riboflavin are also extracted. The extraction of these vitamins is the greatest at 65°C and is indirectly linked to the amylase activity. When the starches are broken down during mashing, the thiamine and riboflavin vitamers are gradually released into the mash liquor. The boiling and trub removal (whirlpool) processes impose losses in both vitamins owing to the high temperatures exhibited during these stages. While hop pellets were shown to contribute a small proportion of the vitamers studied, the use of kettle finings caused a significant reduction in both thiamine and riboflavin vitamers.
Description:
The vitamin content of beer and brewing related products might not only be of interest from a human health perspective, but determining their presence and relative quantities might also help to understand the role they play in product stability. Water-soluble vitamins are important in the brewing industry, as they are essential nutrients for yeasts and potential spoilage organisms. The presence of particular vitamins in beer has been linked to deterioration (light strike) and it is possible that many vitamins may be linked to increased bacterial spoilage potential in beer. There is strong evidence to support that lactic acid bacteria require a variety of vitamins in order to grow effectively and can aid in the increased spoilage of beer and beer related products. This study investigates the effect of a variety of water-soluble vitamins on the growth of commonly found spoilage organisms, Lactobacillus brevis and Pediococcus damnosus.
Description:
The vitamin content of beer and brewing related products might not only be of interest from a human health perspective, but determining their presence and relative quantities might also help to understand the role they play in product stability. Water-soluble vitamins are important in the brewing industry, as they are essential nutrients for yeasts and potential spoilage organisms. The presence of particular vitamins in beer has been linked to deterioration (light strike) and it is possible that many vitamins may be linked to increased bacterial spoilage potential in beer. There is strong evidence to support that lactic acid bacteria require a variety of vitamins in order to grow effectively and can aid in the increased spoilage of beer and beer related products. This study investigates the effect of a variety of water-soluble vitamins on the growth of commonly found spoilage organisms, Lactobacillus brevis and Pediococcus damnosus.
Description:
A simple and effective method for the analysis of thiamine (B1) and riboflavin (B2) vitamers, in unmalted and malted grains, by high performance liquid chromatography (HPLC) has been developed. This method makes use of trichloroacetic acid (TCA) as an extraction medium to effectively clean up the sample and analyze the vitamer content with high accuracy (R2 > 0.9992; %RSD < 5%). This method was employed in the routine analysis of a wide range of malted and unmalted grains, and it was found that lighter colored malts contain higher concentrations (2–5 times higher) of thiamine and riboflavin vitamers compared to darker colored malts. The malting process has no effect on the overall riboflavin content; however, both steeping and kilning processes cause increases in thiamine vitamer content. Roasting profiles show that thiamine and riboflavin vitamer concentrations are significantly effected when the temperature reaches 120 °C, which explains why roasted products have lower vitamer content than paler malts.
Description:
A simple and effective method for the analysis of thiamine (B