Study on the methodology for the quantification of carbon dioxide in wine using a quartz crystal microbalance

A new method for carbon dioxide (CO₂) determination in wine is proposed, based on the use of a quartz crystal microbalance. The analytical experimental set-up was made in the laboratory, and the methodology, free of interference and with an easy calibration procedure, is adequate to monitor CO₂ in wine.     

Quality control method based on quartz crystal microbalance and WGA for flour milled from germinated wheat

Plasma membrane is the initial sensor of different stress conditions and its composition is modified with response to environmental changes. In the present study, we have modified the lipid composition of the membrane by growing Saccharomyces cerevisiae in the presence of different fatty acids and ergosterol. All supplemented fatty acids were incorporated into the cell and this incorporation produced significant changes in the lipid composition. The incubation with ergosterol also modified the lipid composition of the cells; however, these cells presented a strong reduction in the content of this sterol. The different cellular lipid composition has been related to viability and fermentation performance at low temperature (13 °C). The cells incubated with palmitoleic acid (C16:1) showed higher viability and significant reduction in the fermentation length. These cells presented higher C16:1 and ergosterol content, shorter chain length of the fatty acids and higher ratio of sterols/phospholipids. Therefore redesigning the composition of cellular membranes during industrial yeast propagation seems to be a promising strategy for improving fermentation performance in the winery.     

A non-destructive method to monitor changes in a troponin T peptide in beef drip with a monoclonal antibody

To simplify the monitoring of postmortem beef aging, we established a system to detect a troponin T (TnT) peptide fragment in bovine muscle drip (natural exudates) with an original monoclonal antibody. The antibody was raised against a synthetic peptide APPPPAEVPEVHEEVH corresponding to the N-terminal region of bovine fast-type TnT. In a competitive enzyme-linked immunosorbent assay (ELISA), our antibody detected the standard peptide dose-dependently. According to the monitoring examination with a competitive ELISA during 22 days postmortem, the concentration of the peptide in both the drip and trichloroacetic acid extracts from the longissimus muscle (n = 4) significantly increased in parallel, up to 10 nmol/ml and 16.4 nmol/g at day 14 postmortem, respectively. These events were accompanied by an increase in the conventional 30 kDa fragment in western blot analysis and a decrease in the Warner–Bratzler shear force value of the beef from 5.0 to 2.4 N/cm². The peptide detection system using drips with the antibody has advantages applicable to a non-destructive, simple, quick, and on-site monitoring method, such as immunochromatography.