Development and validation of a grouping method for pesticides analysed in foodstuffs

The cost effective monitoring of hundreds of pesticide residues in foodstuffs of vegetable origin involves the definition of groups of analytes associated with homogeneous performance parameters of the used analytical method. The performance of the analytical method only needs to be tested on a daily base for some of these group’s compounds. This work proposes a strategy for defining groups of compounds with homogeneous physical–chemical properties based on the evaluation of the similarity of the multivariate pattern of five of these properties namely: molar mass, melting point, vapour pressure at 20 °C, n-octanol–water partition coefficient and solubility in water at 20 or 25 °C. Three independent and competing multivariate analysis tools, namely Principal Component Analysis, Hierarchical Clustering and K-Mean Clustering were used. This strategy was successfully used to group 100 pesticides into nine clusters, with 1–40 pesticides, represented by a compound with within group average properties. The developed grouping method was validated using physical–chemical data from other references or compounds and produced groups consistent with the performance of the studied determination of pesticide residues in dried red bean. The mean analyte recoveries of groups with larger dimension are statistically different for a confidence level of 95%. The within group coefficients of variance of mean analyte recoveries of larger groups ranged from 6.7% to 8.5%. This grouping method can reduce the number of recovery tests performed for the validation of the analytical method or test quality control.     

Structure and Functionality of Whey Protein Concentrate-Based Products with Different Water Contents

Properties of different heated mixtures of whey protein concentrate, starch, gelatin, and sucrose with different water contents were studied. The water activity of samples was determined. The structural properties were analyzed by confocal laser scanning microscopy, solubility assays in different extraction solutions, polyacrylamide gel electrophoresis, and differential scanning calorimetry. Color, texture, and water-holding capacity of samples were also determined. Results show that a certain water content it is needed to form a structure with solid characteristics in these mixtures. The temperature for starch gelatinization is lower than the temperature for whey proteins denaturation, but when sucrose is present, whey proteins are denatured, before the gelatinization of starch. Sucrose is major contributor to the adhesiveness of the samples and to the decrease of their water activity. Also, sucrose decreases the firmness and cohesiveness of the samples. The main component that contributes to the browning of the samples during the heat treatment is whey protein concentrate, whereas starch is the main component responsible for the water-holding capacity in these samples. Gelatin does not modify appreciably the properties of the mixtures in the proportion used in these assays.     

Microbial polysaccharide‐based membranes: Current and future applications

Microbial polysaccharides are characterized by high molecular structure variability which translates into a wide range of different properties offering interesting opportunities for application in many different areas, including membrane‐based products and processes. Due to their new or improved properties, microbial polysaccharides can replace plant, algae, and animal products, either in their traditional or in new applications. The main constraint to their wider use is the production costs that are still higher than that of other natural and synthetic polymers. The current applications of microbial polysaccharide membranes in medical, food, and industrial processes are outlined. The limitations still faced by these membranes and the requirements for obtaining innovative products and processes are also addressed. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014 , 131, 40047.     

Remediation of waters contaminated with MCPA by the yeasts Lipomyces starkeyi entrapped in a sol-gel zirconia matrix

A single-stage sol-gel route was set to entrap yeast cells of Lipomyces starkeyi in a zirconia (ZrO(2)) matrix, and the remediation ability of the resulting catalyst toward a phenoxy acid herbicide, 4-chloro-2-methylphenoxyacetic acid (MCPA), was studied. It was found that the experimental procedure allowed a high dispersion of the microorganisms into the zirconia gel matrix; the ZrO(2) matrix exhibited a significant sorption capacity of the herbicide, and the entrapped cells showed a degradative activity toward MCPA. The combination of these effects leads to a nearly total removal efficiency (>97%) of the herbicide at 30 °C within 1 h incubation time from a solution containing a very high concentration of MCPA (200 mg L(-1)). On the basis of the experimental evidence, a removal mechanism was proposed involving in the first step the sorption of the herbicide molecules on the ZrO(2) matrix, followed by the microbial degradation operated by the entrapped yeasts, the metabolic activity of which appear enhanced under the microenvironmental conditions established within the zirconia matrix. Repeated batch tests of sorption/degradation of entrapped Lipomyces showed that the removal efficiency retained almost the same value of 97.3% after 3 batch tests, with only a subsequent slight decrease, probably due to the progressive saturation of the zirconia matrix.     

Ground Distance Relaying With Fault-Resistance Compensation for Unbalanced Systems

Fault resistance is a critical variable in distance relaying. If not considered due to underreaching phenomenon, it may cause the misoperation of ground distance relays for internal faults. Still, as a consequence of the overreaching phenomenon, the unbalanced nature of loads and asymmetry of lines can affect the distance protection operation efficiency. Mainly due to these aspects, there is low precision in protection zone limits of ground distance relays. In this paper, a new algorithm is proposed to increase the precision of these limits, improving efficiency in the distance protection process. The proposed method is based in phase coordinates and uses a fault resistance estimate to develop the trip decision procedure. The results show that the algorithm is suitable for online applications, and that it has an independent performance from the fault resistance magnitude, the fault location, and the line asymmetry.     

Functional Foods and Nondairy Probiotic Food Development: Trends,Concepts, and Products

ABSTRACT: Recently, the focus of scientific investigations has moved from the primary role of food as the source of energy and body‐forming substances to the more subtle action of biologically active food components on human health. There has been an explosion of consumer interest in the active role of food in the well‐being and life prolongation, as well as in the prevention of initiation, promotion, and development of nontransmissible chronic diseases. As a result, a new term—functional food—was proposed. Among these foods, probiotics may exert positive effects on the composition of gut microbiota and overall health, and the market is increasing annually. An increased demand for nondairy probiotic products comes from vegetarianism, milk cholesterol content, and lactose intolerance. Therefore, the development of these products is a key research priority for food design and a challenge for both industry and science sectors. This article presents an overview of functional food development, emphasizing nondairy foods that contain probiotic bacteria strains.