Direct determination of amino acids in brewery worts produced by different processes by capillary zone electrophoresis

Polypyrrole/carbon dot nanocomposite as an electrochemical biosensor for liquid biopsy analysis of tryptophan in the human serum of normal and breast cancer women

Liquid biopsy analysis represents a suitable alternative analysis procedure in several cases where no tumor tissue is available or in poor patient conditions. Amino acids can play a crucial role in aiding cancer diagnosis. Monitoring of tryptophan (Trp) catabolism can aid in tracking cancer progression. Therefore, a novel nanocomposite was fabricated using overoxidized polypyrrole film doped with nano-carbon dots (nano-CDs) on the pencil graphite electrode (PGE) surface for sensitive evaluation of Trp in human serum. Using square wave voltammetry (SWV), the overoxidized polypyrrole/carbon dots/pencil graphite electrode (Ov-Ox PPy/CDs/PGE) achieved excellent electrochemical catalytic activity for evaluating Trp. The modified electrode, known as Ov-Ox PPy/CDs/PGE, demonstrated superior electrochemical catalytic activity compared to bare PGE, CDs/PGE, PPy/PGE, and PPy/CDs/PGE for evaluation of Trp. The method's excellent sensitivity was confirmed by the low limits of detection (LOD = 0.003 μmol L-1) and limit of quantitation (LOQ = 0.009 μmol L-1). The biosensor that was developed can measure tryptophan (Trp) levels in the serum of both healthy individuals and female breast cancer patients with high accuracy and sensitivity. The results indicate that there is a significant difference, as shown by the F-test, between healthy individuals and those with breast cancer. This suggests that Trp amino acid could be an essential biomarker for cancer diagnosis. Consequently, liquid biopsy analysis presents a valuable opportunity for early disease detection, particularly for cancer.

Occurrence of melatonin and indolic compounds derived from l-tryptophan yeast metabolism in fermented wort and commercial beers

Melatonin and serotonin are bioactive compounds present in foods and beverages and related to neuroprotection and anti-angiogenesis, among other activities. They have been described in wines and the role of yeast in their formation is clear. Thus, this study evaluates the content of these bioactives and other related indolic compounds in beer. For this purpose, commercial beers were analyzed by a validated UHPLC-HRMS method and sample treatment optimized due to the low concentrations expected. Moreover, a wort was fermented with different commercial beer yeast (Abbaye, Diamond, SafAle, SafLager) in order to monitor the formation of these bioactives during the elaboration process. Results show that indolic compounds such as N-acetylserotonin and 3-indoleacetic acid are produced during the alcoholic fermentation of wort. Moreover, the occurrence of four indolic compounds (5-hydroxytryptophan, N-acetylserotonin, 3-indoleacetic acid, l-tryptophan ethyl ester) in commercial beers is reported for the first time.

Evaluation of craft beers through the direct determination of amino acids by capillary electrophoresis and principal component analysis

The composition of beer wort in terms of amino acid (AA) content affects the final product quality, once it is related to the vitality of yeast during the initial exponential growth phase and throughout fermentation. The objective of this work was the use of a capillary zone electrophoresis method with UV-vis detection in association with Principal Component (Data) Analysis for craft beer classification. Cysteine, histidine, phenylalanine, lysine, tryptophan and arginine were the monitored AAs in wort and finished beer, which were extracted through cation exchange resin. Good differentiation among samples according to their production was obtained, showing a profile of AAs (<LQ-99 µg mL^-1) for each wort, which can be used as indicator of the quality of a beer. One of the samples had the mashing step monitored, showing an increasing profile in the concentrations of AAs (6.5-55 µg mL^-1), which can be explained by the protein cleavage.

Effect of Maize as Adjunct and the Mashing Proteolytic Step on the Brewer Wort Composition

The partial substitution of barley malt has been one of the main strategies of breweries to reduce production costs. In Brazil, as in other countries, maize is a raw material that is used mostly for this purpose. Aiming for strategic cost management, some large breweries have adopted a reduction in the time and energy costs of the process. As an example, changes have been made to the traditional mashing curves by reducing the times or omitting the proteolytic step. The objective of this work was to compare the physical and chemical aspects of sweet and bitter worts prepared through experimental design with and without the addition of maize as adjunct, as well as the execution or not of the proteolytic step in mashing. Color, total acidity, extract, total reducing sugars, total phenolic compounds, and proteins content were evaluated. In addition, the antioxidant activity was determined. The wort obtained with maize and not submitted to the proteolytic step presented a bright color as well as reduced phenolic compounds, protein, and antioxidant activity. Comparatively, the action of proteases in the wort resulted in a greater release of total reducing sugars, a more intense color, and a higher content of total nitrogen and phenolic compounds. The results indicate that despite being an alternative to reduce costs in the brewing process, the use of the adjunct and the exclusion of the proteolytic step of mashing will imply a poor wort in regards to nutrition, which can compromise the activity of the yeast during the process and therefore affect the quality of the final product.

A FRET-based ratiometric fluorescent probe for highly selective detection of cysteine based on a coumarin–rhodol derivative

A ratiometric fluorescent probe for detecting cysteine was designed and synthesized based on the fluorescence resonance energy transfer (FRET) process.