Modeling the antioxidant capacity of red wine from different production years and sources under censoring

Experimental Design for the Lifetime Performance Index of Weibull Products Based on the Progressive Type I Interval Censored Sample

In this study, the experimental design is developed based on the testing procedure for the lifetime performance index of products following Weibull lifetime distribution under progressive type I interval censoring. This research topic is related to asymmetrical probability distributions and applications across disciplines. The asymptotic distribution of the maximum likelihood estimator of the lifetime performance index is utilized to develop the testing procedure. In order to reach the given power level, the minimum sample size is determined and tabulated. In order to minimize the total cost that occurred under progressive type I interval censoring, the sampling design is investigated to determine the minimum number of inspection intervals and equal interval lengths when the termination time of experiment is fixed or not fixed. For illustrative aims, one practical example is given for the implementation of our proposed sampling design to collect the progressive type I interval censored sample so that the users can use this sample to test if the lifetime performance index exceeds the desired target level.

Missing Data Calculation Using the Antioxidant Activity in Selected Herbs

In this paper, a model has been developed that can estimate the composition of the phenol compounds, based on censored data and the total equivalent antioxidant capacity (TEAC) measured by three different methods. A contingency of 32 plants was analyzed: total phenolic content (TPC), caffeic acid, p-coumaric acid, ferulic acid, neochlorogenic acid and TEAC. They were measured by three different methods: ABTS (2,20-azinobis-(3-ethylbenzthiazoline- 6-sulfonic acid)), DPPH (1,1-diphenyl-2-picrylhydrazyl radical) and FRAP (ferric reducing/antioxidant power). Five values of caffeic-, thirteen of p-coumaric-, seven of ferulic-, and nineteen neochlorogenic acids were missing. Due to the complexity of the compounds, data mining and computational methods are required to determine the missing data. The method developed for independent variables was used to estimate the missing data. The contingency was filled with the calculated values obtained with all alternatives. The performance of each approach is shown in the estimation and/or prediction of the phenolic composition compared to the approaches used. The results indicated a strong correlation and mutual influence between the data analyzed.

CUPRAC Voltammetric Determination of Antioxidant Capacity in Tea Samples by Using Screen-Printed Microelectrodes

Measurement of antioxidant capacity represents an analytical major challenge in terms of accuracy, efficiency, rapid response, or low cost of detection methods. Quantification of antioxidant capacity of food samples using disposable screen-printed microelectrodes (SPMEs) was based on cyclic voltammetry versus open-circuit potential (CV vs OCP) and differential pulse voltammetry (DPV) as compared with spectrophotometric measurement of the CUPRAC reaction with 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (trolox). The SPMEs are organic-resistant electrodes and thus compatible with food samples and organic solvents used to dissolve trolox. A micropipette was used to release a drop of 50 μL sample on the spotted surface of the SPME sensor/working electrode that was time programmed to function according to the working protocol. The SPME response was linearly correlated with trolox content. This preliminary demonstration was focused on the analysis of tea infusions, due to the simplicity and reproducibility of the samples' preparations involved. Analytical results of the antioxidant capacity (expressed as mol·L^-1 trolox equivalents) of the tea samples showed a good agreement in the case of spectrophotometry and differential pulse voltammetry (R ² > 0.998). DPV with SPME based on CUPRAC reactions was proven to be a promising approach for the characterization of antioxidant capacity of tea samples with rapid response, cost-effectiveness, and simplicity of operation.

Antioxidant Capacity: Experimental Determination by EPR Spectroscopy and Mathematical Modeling

A new method of determining antioxidant capacity based on a mathematical model is presented in this paper. The model was fitted to 1000 data points of electron paramagnetic resonance (EPR) spectroscopy measurements of various food product samples such as tea, wine, juice, and herbs with Trolox equivalent antioxidant capacity (TEAC) values from 20 to 2000 μmol TE/100 mL. The proposed mathematical equation allows for a determination of TEAC of food products based on a single EPR spectroscopy measurement. The model was tested on the basis of 80 EPR spectroscopy measurements of herbs, tea, coffee, and juice samples. The proposed model works for both strong and weak antioxidants (TEAC values from 21 to 2347 μmol TE/100 mL). The determination coefficient between TEAC values obtained experimentally and TEAC values calculated with proposed mathematical equation was found to be R(2) = 0.98. Therefore, the proposed new method of TEAC determination based on a mathematical model is a good alternative to the standard EPR method due to its being fast, accurate, inexpensive, and simple to perform.

Antibacterial, antiviral, and antifungal properties of wines and winery byproducts in relation to their flavonoid content

Grapes produce organic compounds that may be involved in the defense of the plants against invading phytopathogens. These metabolites include numerous phenolic compounds that are also active against human pathogens. Grapes are used to produce a variety of wines, grape juices, and raisins. Grape pomace, seeds, and skins, the remains of the grapes that are a byproduct of winemaking, also contain numerous bioactive compounds that differ from those found in grapes and wines. This overview surveys and interprets our present knowledge of the activities of wines and winery byproducts and some of their bioactive components against foodborne (Bacillus cereus, Campylobacter jejuni, Escherichia coli, Listeria monocytogenes, Salmonella enterica, Staphylococcus aureus, Yersinia enterocolitica, Vibrio cholerae, Vibrio vulnificus), medical (Helicobacter pylori, Klebsiella pneumoniae), and oral pathogenic bacteria, viruses (adeno, cytomegalo, hepatitis, noro, rota), fungi (Candida albicans, Botrytis cinerea), parasites (Eimeria tenella, Trichomonas vaginalis), and microbial toxins (ochratoxin A, Shiga toxin) in culture, in vivo, and in/on food (beef, chicken, frankfurters, hot dogs, lettuce, oysters, peppers, pork, sausages, soup, spinach) in relation to composition and sensory properties. Also covered are antimicrobial wine marinades, antioxidative and immunostimulating aspects, and adverse effects associated with wine consumption. The collated information and suggested research needs might facilitate and guide further studies needed to optimize the use of wines and byproducts to help improve microbial food safety and prevent or treat animal and human infections.