Potentiometric Determination of Aluminum in Foods, Pharmaceuticals, and Alloys by AlMCM-41-Modified Carbon Paste Electrode

A new chemically modified electrode is constructed by incorporating AlMCM-41 into carbon paste matrix (AlMCM-41-MCPE) and used as a sensitive sensor for detection of aluminum in aqueous and nonaqueous solutions. The rapid exchange kinetics in the membrane results in a near-Nernstian behavior of the modified electrode and makes it a suitable potentiometric sensor for detection of aluminum. A linear response in concentration range from 1.0?×?10^?6 to 1.0?×?10^?1 mol/L (0.027 μg/mL–2.7 mg/mL) was obtained with a detection limit of 4.6?×?10^?7 mol/L for the potentiometric detection of aluminum. Selectivity coefficients of a number of interfering cations have been estimated. The interference from many of the investigated ions is negligible. The AlMCM-41-MCPE is suitable for use in aqueous solution of pH 2–6 and in partially nonaqueous medium. The modified electrode exhibited a fast response time (~8 s), good stability, and an extended lifetime. The developed sensor was used successfully for the determination of Al³⁺ in some alloys, drugs, and food products.     

Comparative efficacy of Zataria multiflora Boiss., Origanum compactum and Eugenia caryophyllus essential oils against E. coli O157:H7, feline calicivirus and endogenous microbiota in commercial baby-leaf salads

Ready-to-eat salads using baby-leaf and multi-leaf mixes are one of the most promising developments in the fresh-cut food industry. There is great interest in developing novel decontamination treatments, which are both safe for consumers and more efficient against foodborne pathogens. In this study, emulsions of essential oils (EOs) from Origanum compactum (oregano), Eugenia caryophyllus (clove), and Zataria multiflora Boiss (zataria) were applied by spray (0.8 ml) after the sanitizing washing step. The aim was to investigate their ability to control the growth of potentially cross-contaminating pathogens and endogenous microbiota in commercial baby leaves, processed in a fresh-cut produce company. Zataria EO emulsions of 3%, 5% and 10% reduced Escherichia coli O157:H7 by 1.7, 2.2 and 3.5 log cfu/g in baby-leaf salads after 5 days of storage at 7 °C. By contrast, reductions in E. coli O157:H7 counts remained the same when clove was applied at concentrations of 5% and 10% (2.5 log cfu/g reduction). Oregano (10%) reduced inoculated E. coli O157:H7 counts in baby-leaf salads by a maximum of 0.5 log cfu/g after 5 days of storage. Zataria showed strong antimicrobial efficacy against E. coli O157:H7 and also against the endogenous microbiota of baby-leaf salads stored for 9 days. Feline calicivirus (FCV), a norovirus surrogate, survived on inoculated baby-leaf salads during refrigerated storage (9 days at 7 °C) regardless of treatment. Refrigeration temperatures completely annulled the effectiveness of the EOs against FCV inoculated in baby-leaf salads as occurred in FCV cultures. This study shows that EOs, and zataria in particular, have great potential use as an additional barrier to reduce contamination-related risks in baby-leaf salads. However, further research should be done into foodborne viruses in order to improve food safety.     

The proteolytic activity of selected lactic acid bacteria in fermenting cow's and camel's milk and the resultant sensory characteristics of the products

The aim of this study was to evaluate the proteolytic activities of 14 strains of lactic acid bacteria and their impact on sensory characteristics of the resultant fermented cow and camel milk. The results showed that Lactobacillus rhamnosus PTCC 1637 and Lactobacillus fermentum PTCC 1638 had high protease activity and high mean values for sensory quality in fermented cow's and camel's milk. Lactobacillus plantarum PTCC 1058 revealed high protease activity and sensory scores in camel milk. Consequently, milk fermentation using such strains might be recommended for the development of dairy products containing bioactive peptides.     

The effects of resveratrol intake on weight loss: a systematic review and meta-analysis of randomized controlled trials

Abstract

This systematic review and meta-analysis of randomized controlled trials (RCTs) was conducted to summarize the effect of resveratrol intake on weight loss. We searched the following databases until July 2018: MEDLINE, EMBASE, Web of Science and Cochrane Central Register of Controlled Trials. Data were pooled using the inverse variance method and expressed as standardized mean difference (SMD) with 95% confidence intervals (95% CI). Out of 831 reports, 36 RCTs were eligible for including to our meta-analysis. The pooled results, using random-effects model showed that resveratrol supplementation significantly decreased body weight (SMD?=??0.17; 95% CI, ?0.33, ?0.01; P?=?0.03; I²: 62.6), body mass index (BMI) (SMD?=??0.20; 95% CI, ?0.35, ?0.05; P?=?0.01; I²: 60.6), fat mass (SMD?=??0.32; 95% CI, ?0.62, ?0.03; P?=?0.03; I²: 77.9) and waist circumference (WC) (SMD?=??0.42; 95% CI, ?0.68, ?0.16; P?=?0.001; I²: 75.2), and significantly increased lean mass (SMD?=?1.21; 95% CI, 0.75, 1.67; P?<?0.001; I²: 87.6). We found no significant effect of resveratrol administration on leptin (SMD?=??0.20; 95% CI, ?0.68, 0.27; P?=?0.40; I²: 85.3) and adiponectin levels (SMD?=?0.08; 95% CI, ?0.39, 0.55; P?=?0.74; I²: 91.0). Resveratrol supplementation significantly decreased body weight in obese patients (SMD ?0.43; 95% CI, ?0.60, ?0.26) compared with other diseases (SMD 0.02; 95% CI, ?0.29, 0.33), and type 2 diabetes mellitus (SMD ?0.17; 95% CI, ?0.37, 0.02). Overall, the current meta-analysis demonstrated that resveratrol intake significantly reduced weight, BMI, WC and fat mass, and significantly increased lean mass, but did not affect leptin and adiponectin levels.     

The effect of Nafion content in a graphitized carbon nanofiber-based anode for the direct methanol fuel cell

The performance and stability of a direct methanol fuel cell (DMFC) with membrane electrode assemblies (MEA) using different Nafion^® contents (30, 50 and 70 wt% or MEA30, MEA50 and MEA70, respectively) and graphitized carbon nanofiber (GNF) supported PtRu catalyst at the anode was investigated by a constant current measurement of 9 days (230 h) in a DMFC and characterization with various techniques before and after this measurement. Of the pristine MEAs, MEA50 reached the highest power and current densities. During the 9-day measurement at a constant current, the performance of MEA30 decreased the most (−124 μV h⁻¹), while the MEA50 was almost stable (−11 μV h⁻¹) and performance of MEA70 improved (+115 μV h⁻¹). After the measurement, the MEA50 remained the best MEA in terms of performance. The optimum anode Nafion content for commercial Vulcan carbon black supported PtRu catalysts is between 20 and 40 wt%, so the GNF-supported catalyst requires more Nafion to reach its peak power. This difference is explained by the tubular geometry of the catalyst support, which requires more Nafion to form a penetrating proton conductive network than the spherical Vulcan. Mass transfer limitations are mitigated by the porous 3D structure of the GNF catalyst layer and possible changes in the compact Nafion filled catalyst layers during constant current production.     

Effects of hot pressing conditions on the performance of Nafion membranes coated by ink-jet printing of Pt/MWCNTs electrocatalyst for PEMFCs

In our previous work, a hydrothermal method was employed to prepare Pt/MWCNTs nanocomposites with 20 wt.% Pt, a low mean Pt nanoparticles size (2.8 nm) and a specific surface area of 99 m² g⁻¹. In this work, the membrane electrode assemblies (MEAs) with hydrothermally synthesized Pt/MWCNTs nanocatalysts were fabricated by catalyst-coated membrane (CCM) method. For this purpose, a commercial HP inkjet printer was used to deposit Pt/MWCNTs ink (as catalyst ink) directly on to the substrate (Nafion membrane or decal substrate) with a loading of 0.2 mg cm⁻² Pt for both the anode and cathode. The effects of hot-pressing conditions on the performance of MEAs were investigated through Taguchi design of experiments method using temperature (100 and 130 °C), pressure (800 and 1000 psi) and time (3 and 5 min) as effective experimental parameters. The compression ratios of MEAs were determined by testing the thicknesses before and after hot-pressing process. The performance of MEAs was characterized by the polarization curves and cyclic voltammetry (CV) and the surface morphologies of the electrodes were observed by scanning electron microscopy (SEM). The results showed that the most appropriate hot-pressing conditions were 800 psi, 100 °C, and 3 min. Electrochemical analysis and physical property examination revealed that the MEA fabricated by CCM method has a better performance compared to the one prepared by conventional decal transfer (DT) method.     

Solid‐State Protein–Carbohydrate Interactions and Their Application in the Food Industry

The growing interest in food component interactions, especially the solid‐state protein–carbohydrate ones, has led to a growing body of knowledge on the effects of these interactions on the physical, chemical, and structural properties of compositionally complex food systems. The goal of the present review is to survey the critical mechanisms involved in protein–carbohydrate interactions as a key step toward the rational formulation and processing of protein‐ and carbohydrate‐rich foods to produce products with desirable properties without adverse reactions. The hypotheses proposed on the stabilizing effects of carbohydrates on proteins and the role of different types of sugars in the extent of these interactions are reviewed in this article. Another aspect of this review involves the successful drying of proteins by spray‐drying, freeze‐drying, and supercritical‐fluid‐drying using carbohydrates. Finally, applications of these interesting phenomena to produce important food products including milk powder, infant formulas, bakery products, and fruit and vegetable juice powders are investigated.     

Effect of chitosan edible coating enriched with lemon verbena extract and essential oil on the shelf life of vacuum rainbow trout (Oncorhynchus mykiss)

In this research, the antioxidant and antibacterial characteristics of the chitosan (CH) coating incorporated with lemon verbena essential oil (LVEO) and extract (LVE) on the quality of the rainbow trout packed by vacuum packaging at 4°C were investigated. Samples evaluated include the following: Control, VP, CH, CH-LVE 2%, CH-LVEO 1%, and CH-LVE 1%-LVEO 0.5% for 16 days at 3 days intervals. All of the samples significantly reduced Psychrotrophic bacteria, total viable counts, Enterobacteriaceae, and H₂S producing bacteria as compared with control during keeping time. Thiobarbituric acid reactive substance, peroxide value, total volatile basic nitrogen, and pH value were detected lower in all of the samples than control. CH incorporated with LVE and LVEO gave an agreeable effect on sensory characteristics. Samples containing CH-LVE 1%-LVEO 0.5% was often in priority by sensory assessors. Generally, LV can be applied as a substitution for chemical preservatives in fish meat.