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This project was aimed to identify the quenching chemistry of biologically important reactive oxygen and nitrogen species (ROS/RNS, including radicals), to show antioxidant action against reactive species through H‐atom and electron transfer reactions, and to evaluate the ROS/RNS scavenging activity of antioxidants with existing analytical methods while emphasizing the underlying chemical principles and advantages/disadvantages of these methods. In this report, we focused on the applications and impact of existing assays on potentiating future research and innovations to evolve better methods enabling a more comprehensive study of different aspects of antioxidants and to provide a vocabulary of terms related to antioxidants and scavengers for ROS/RNS. The main methods comprise the scavenging activity measurement of the hydroxyl radical (•OH), dioxide(•1–) (O2•–: commonly known as the superoxide radical), dihydrogen dioxide (H2O2: commonly known as hydrogen peroxide), hydroxidochlorine (HOCl: commonly known as hypochlorous acid), dioxidooxidonitrate(1–) (ONOO−: commonly known as the peroxynitrite anion), and the peroxyl radical (ROO•). In spite of the diversity of methods, there is currently a great need to evaluate the scavenging activity of antioxidant compounds in vivo and in vitro. In addition, there are unsatisfactory methods frequently used, such as non-selective UV measurement of H2O2 scavenging, producing negative errors due to incomplete reaction of peroxide with flavonoids in the absence of transition metal ion catalysts. We also discussed the basic mechanisms of spectroscopic and electrochemical nanosensors for measuring ROS/RNS scavenging activity of antioxidants, together with leading trends and challenges and a wide range of applications. This project aids in the identification of reactive species and quantification of scavenging extents of antioxidants through various assays, makes the results comparable and more understandable, and brings a more rational basis to the evaluation of these assays and provides a critical evaluation of existing ROS/RNS scavenging assays to analytical, food chemical, and biomedical/clinical communities by emphasizing the need for developing more refined, rapid, simple, and low‐cost assays and thus opening the market for a wide range of analytical instruments, including reagent kits and sensors. [ABSTRACT FROM AUTHOR]

Immunoglobulin G (IgG) represents the major fraction of antibodies in healthy adult human serum, and deviations from physiological levels are a generic marker of disease corresponding to different pathologies. Therefore, screening methods for IgG evaluation are a valuable aid to diagnostics. The present work proposes a rapid, automatic, and miniaturized method based on UV-vis micro-bead injection spectroscopy (μ-BIS) for the real-time determination of human serum IgG with label-free detection. Relying on attachment of IgG in rec-protein G immobilized in Sepharose 4B, a bioaffinity column is automatically assembled, where IgG is selectively retained and determined by on-column optical density measurement. A 'dilution-and-shoot' approach (50 to 200 times) was implemented without further sample treatment because interferences were flushed out of the column upon sample loading, with minimization of carryover and cross-contamination by automatically discarding the sorbent (0.2 mg) after each determination. No interference from human serum albumin at 60 mg mL in undiluted sample was found. The method allowed IgG determination in the range 100-300 μg mL (corresponding to 5.0-60 mg mL in undiluted samples), with a detection limit of 33 μg mL (1.7 mg mL for samples, dilution factor of 50). RSD values were < 9.4 and < 11.7%, for intra and inter-assay precision, respectively, while recovery values for human serum spiked with IgG at high pathological levels were 97.8-101.4%. Comparison to commercial ELISA kit showed no significant difference for tested samples ( n = 8). Moreover, time-to-result decreased from several hours to < 5 min and analysis cost decreased 10 times, showing the potential of the proposed approach as a point-of-care method. [ABSTRACT FROM AUTHOR]

Grape pomace extract (GPE) is a by-product from the wine industry that is rich in bioactive compounds. The effect of Touriga nacional GPE on quality characteristics (composition, pH, color variables and antioxidant capacity) of mechanically deboned chicken meat (MDM) under frozen storage was evaluated. Two MDM samples with different compositions fortified with two levels of GPE (60 and 120 mg/kg) were tested and analyzed within 1 and 210 days of storage. Data obtained was evaluated by principal component analysis (PCA) and the first two PCs accounted for 85% of the total variability. PC1 (47.9%) was positively correlated with a* (redness) and chroma, while negatively correlated with antioxidant indexes. PC2 (36.7%) was positively correlated with b* (yellowness) and Hue angle, and likewise PC1 negatively correlated with antioxidant properties. In conclusion, the addition of GPE to MDM is feasible to maintain the antioxidant properties and contributes positively to MDM color attributes over frozen storage, even using MDM batches with different proximal composition. Practical Applications This research targets two practical applications. First, it highlights the use of grape pomace extract as a sustainable source of bioactive compounds, namely antioxidants, as grape pomace is a by-product from the wine industry. Second, it demonstrates that the quality of mechanically deboned chicken meat under frozen storage can be maintained after grape pomace addition. Future incorporation of mechanically deboned chicken meat supplemented with grape pomace extract in comminuted products is envisioned. [ABSTRACT FROM AUTHOR]