Effects of ionizing radiation on organic volatile compounds from PEA protein isolate.

Food irradiation is a preservation technique and in respect with regulations, is applied to a limited number of products. Nevertheless, this technique could be interesting for products sensitive to heat treatment, and to limit alteration caused to their organoleptic characteristics. This study concerns the potential of ionization for vegetable proteins, to limit the damage on the sensory properties that can be caused by thermal treatments. The impact of ß-ionizing was measured on the volatile compounds of five pea protein isolates. These isolates were subjected to ionizing radiation of 10 MeV electron beam and the volatile compounds were compared by SPME-GC-MS before and after the treatment. ß-Ionization led to a major increase in the total amount of volatiles and to appearance of new compounds. We observed a strong increase in aldehydes, that were reported to be involved in pea off-flavor, and the appearance of dimethyl-disulfide, linked to sulfurous off-notes. Many of the compounds impacted by the treatment were linked to protein and lipid oxidations. Mechanisms explaining the impact of ß-ionizing on lipids and protein oxidations were proposed.

Optimization of a Molecularly Imprinted Polymer Synthesis for a Rapid Detection of Caffeic Acid in Wine.

Molecular imprinting is an efficient strategy to make the detection of compounds more specific and more selective. This targeted analytical strategy using molecularly imprinted polymer (MIP) synthesis needs to obtain the optimized conditions. A selective molecularly imprinted polymer was prepared for caffeic acid (CA) detection after varying the following synthesis parameters: functional monomer type (N-phenylacrylamide, N-PAA or methacrylic acid, MAA), solvent type (acetonitrile/methanol or acetonitrile/toluene), and the polymerization method (UV or thermal initiation). The optimal polymer was obtained using MAA as a functional monomer, acetonitrile/methanol as solvent, and UV polymerization. Morphological characterizations were done for the optimal CA-MIP using mid-infrared spectroscopy, scanning electron microscopy, and nitrogen adsorption. The optimal polymer showed good specificity and selectivity in the presence of interferents (antioxidants having a chemical structure close to CA) in a hydroalcoholic solution. The electrochemical detection of CA was performed by cyclic voltammetry (CV) after the interaction between CA and the optimal MIP in a wine sample. The linear range of the developed method was between 0 and 1.11 mM, the limit of detection (LOD) was 0.13 mM, and the limit of quantification (LOQ) was 0.32 mM. HPLC-UV was used to validate the newly developed method. Recovery values were between 104% and 111%.

Sample Preparation and Analytical Techniques in the Determination of Trace Elements in Food: A Review.

Every human being needs around 20 essential elements to maintain proper physiological processes. However, trace elements are classified as beneficial, essential, or toxic for living organisms. Some trace elements are considered essential elements for the human body in adequate quantities (dietary reference intakes, DRIs), while others have undetermined biological functions and are considered undesirable substances or contaminants. Pollution with trace elements is becoming a great concern since they can affect biological functions or accumulate in organs, causing adverse effects and illnesses such as cancer. These pollutants are being discarded in our soils, waters, and the food supply chain due to several anthropogenic factors. This review mainly aims to provide a clear overview of the commonly used methods and techniques in the trace element analysis of food from sample preparations, namely, ashing techniques, separation/extraction methods, and analytical techniques. Ashing is the first step in trace element analysis. Dry ashing or wet digestion using strong acids at high pressure in closed vessels are used to eliminate the organic matter. Separation and pre-concentration of elements is usually needed before proceeding with the analytical techniques to eliminate the interferences and ameliorate the detection limits.

Combination of Screen-Printed Carbon Electrode and Molecularly Imprinted Polymers for the Selective Determination of Phenolic Compounds in Wine.

Caffeic acid (CA) is an efficient antioxidant found in wine and in plants and can be extracted from the by-products of the food industry. A molecularly imprinted polymer specific to caffeic acid (CA-MIP) was prepared by radical polymerization using N-phenylacrylamide as the functional monomer, ethylene glycol dimethacrylate as the cross-linker, and azobisisobutyronitrile as the initiator, in the presence of CA as the template molecule. The rebinding activities between the polymers and CA were promoted by an indirect method and characterized by cyclic voltammetry (CV) using a screen-printed carbon electrode (SPCE). It is a fast method, which only requires simple and portable instrumentation. The polymer showed a high selectivity toward CA and a good repeatability. CA-MIP was then applied in wine samples spiked with CA, and the results were compared to those obtained by a chromatographic method. With a limit of detection of 0.06 mM in wine, the recovery values confirmed that the method is suitable for further applications.

Real-Time Detection of Phenylacetaldehyde in Wine: Application of a Microwave Sensor Based on Molecularly Imprinted Silica.

Molecularly imprinted sol-gel silica (MIS) coupled to a microwave sensor was designed and used to detect phenylacetaldehyde (PAA), a chemical tracer of wine oxidation. The developed method is fast, cheap and could replace the classical chromatographic methods, which require a tedious sample preparation and are expensive. To reach our objective, five MIS and their control non-imprinted silica (NIS) were synthesized and their extraction capacity toward PAA was studied in hydro alcoholic medium. The selected polymers, based on this first step, were subjected to a selectivity study in the presence of PAA and three other competing molecules. The best polymer was integrated in a microwave sensor and was used to assess PAA in red wine. The developed sensor was able to detect PAA at the µg·L-1 level, which is below the off-flavour threshold.

Antioxidant Properties of Ergosterol and Its Role in Yeast Resistance to Oxidation.

Although the functions and structural roles of sterols have been the subject of numerous studies, the reasons for the diversity of sterols in the different eukaryotic kingdoms remain unclear. It is thought that the specificity of sterols is linked to unidentified supplementary functions that could enable organisms to be better adapted to their environment. Ergosterol is accumulated by late branching fungi that encounter oxidative perturbations in their interfacial habitats. Here, we investigated the antioxidant properties of ergosterol using in vivo, in vitro, and in silico approaches. The results showed that ergosterol is involved in yeast resistance to tert-butyl hydroperoxide and protects lipids against oxidation in liposomes. A computational study based on quantum chemistry revealed that this protection could be related to its antioxidant properties operating through an electron transfer followed by a proton transfer mechanism. This study demonstrates the antioxidant role of ergosterol and proposes knowledge elements to explain the specific accumulation of this sterol in late branching fungi. Ergosterol, as a natural antioxidant molecule, could also play a role in the incompletely understood beneficial effects of some mushrooms on health.

The Importance of Developing Electrochemical Sensors Based on Molecularly Imprinted Polymers for a Rapid Detection of Antioxidants.

This review aims to pin out the importance of developing a technique for rapid detection of antioxidants, based on molecular imprinting techniques. It covers three major areas that have made great progress over the years in the field of research, namely: antioxidants characterization, molecular imprinting and electrochemistry, alone or combined. It also reveals the importance of bringing these three areas together for a good evaluation of antioxidants in a simple or complex medium, based on selectivity and specificity. Although numerous studies have associated antioxidants with molecular imprinting, or antioxidants with electrochemistry, but even electrochemistry with molecular imprinting to valorize different compounds, the growing prominence of antioxidants in the food, medical, and paramedical sectors deserves to combine the three areas, which may lead to innovative industrial applications with satisfactory results for both manufacturers and consumers.

Iron intake among Lebanese women: sociodemographic factors, iron-rich dietary patterns, and preparation of hummus, a Mediterranean dish.

BACKGROUND: Plant-based foods such as hummus are alternative to animal protein, and when properly prepared, they help to alleviate nutritional iron deficiency that leads to anemia, a global health problem. OBJECTIVE: The objective was to assess iron intake among Lebanese women and related participant's characteristics, discern iron-rich dietary patterns, evaluate their association with nutrients intake and participant's sociodemographic characteristics, and identify the women preparing hummus traditionally and properly for an enhanced iron bioavailability. DESIGN: A cross-sectional study of 400 Lebanese women (18-74 years old) was conducted in Lebanon. Data from a questionnaire, including sociodemographic and health characteristics, dietary intake, and hummus preparation and consumption, were collected. Dietary data were obtained by a food frequency questionnaire and a 24-h recall. Dietary patterns were identified by principal component analysis. Linear regression and binomial logistic regression models were used to explore the association between the intake of dietary iron, its patterns, and the participants' characteristics. RESULTS: About 60% of the women had iron intake deficiency, especially with lower income (odds ratio [OR] = 1.88, 95% confidence interval [CI]: 1.107, 3.194). Four iron-rich dietary patterns were identified: legumes; organ/lunch meat and chicken; canned fish; and beef and hummus. The factor scores of the latter were positively correlated with protein, vitamin C, iron, folate, vitamin B12, and vitamin A with r = 0.195 and P < 0.01 for all. No significant difference was shown among the women's sociodemographic characteristics for the consumption of the hummus-related pattern. Only 9.2 and 22.7% of the women considered proper preparation of chickpea and hummus, respectively, which significantly (P < 0.05) correlated with older women (66.7%). DISCUSSION & CONCLUSION: The majority of the Lebanese women still have iron intake deficiency and the minority reported proper preparation of hummus. Intervention programs spreading awareness among Lebanese women are needed for encouraging adequate iron intake and considering proper steps to improve iron bioavailability from plant-based food.

Lipid oxidation in oil-in-water emulsions: Iron complexation by buffer ions and transfer on the interface as a possible mechanism.

Lipid oxidation is the main hurdle for omega-3 fatty acid enrichment in food and beverages. Fat oxidation reduces the quality and safety of supplemented products. A tuna oil-in-water emulsion (20%v/v) was exposed to iron-induced oxidation. Emulsions with changing emulsifiers and buffers were analyzed under different storage conditions (argon purging, pH variation) using Conjugated Dienes and Thiobarbituric acid reactive substances assays. The results showed that free iron ions cannot interact with oxygen. However, buffers (Citrate and phosphate) chelate iron ions (Fe (II)). Depending on the pH value and the type of buffer-Fe (II) complex, its prooxidant activity and spatial distribution are influenced. The complex charge defines the interactions with the oil-water interface, i.e., positively charged interfaces repel positively charged complexes which keeps the prooxidant away. The mechanistic understanding of this work will help formulators and product developers to choose the right buffer and emulsifier combination for oxidation sensitive emulsions.

A First Tentative for Simultaneous Detection of Fungicides in Model and Real Wines by Microwave Sensor Coupled to Molecularly Imprinted Sol-Gel Polymers.

A molecularly imprinted silica (MIS) coupled to a microwave sensor was used to detect three fungicides (iprodione, procymidone and pyrimethanil) present in most French wines. Chemometric methods were applied to interpret the microwave spectra and to correlate microwave signals and fungicide concentrations in a model wine medium, and in white and red Burgundy wines. The developed microwave sensor coupled to an MIS and to its control, a nonimprinted silica (NIS), was successfully applied to detect the three fungicides present in trace levels (ng L-1) in a model wine. The MIS sensor discriminated the fungicide concentrations better than the NIS sensor. Partial Least Squares models were suitable for determining iprodione in white and red wines. A preliminary method validation was applied to iprodione in the white and red wines. It showed a limit of detection (LOD) lower than 30 ng L-1 and a recovery percentage between 90 and 110% when the iprodione concentration was higher than the LOD. The determined concentrations were below the authorized level by far.

Detection of Lipid Oxidation in Infant Formulas: Application of Infrared Spectroscopy to Complex Food Systems.

 Fish- or algal oils have become a common component of infant formula products for their high docosahexaenoic acid (DHA) content. DHA is widely recognized to contribute to the normal development of the infant, and the European Commission recently regulated the DHA content in infant formulas. For many manufacturers of first-age early life nutrition products, a higher inclusion level of DHA poses various challenges. Long-chain polyunsaturated fatty acids (LC-PUFAs) such as DHA are very prone to oxidation, which can alter the organoleptic property and nutritional value of the final product. Traditional methods for the assessment of oxidation in complex systems require solvent extraction of the included fat, which can involve harmful reagents and may alter the oxidation status of the system. A rapid, efficient, non-toxic real-time method to monitor lipid oxidation in complex systems such as infant formula emulsions would be desirable. In this study, infrared spectroscopy was therefore chosen to monitor iron-induced oxidation in liquid infant formula, with conjugated dienes and headspace volatiles measured with GC-MS as reference methods. Infrared spectra of infant formula were recorded directly in mid- and near-infrared regions using attenuated total reflectance Fourier-transform (ATR-FTIR) and near-infrared (NIRS) spectrophotometers. Overall, good correlation coefficients (R2 > 0.9) were acquired between volatiles content and infrared spectroscopy. Despite the complex composition of infant formula containing proteins and sugars, infrared spectroscopy was still able to detect spectral changes unique to lipid oxidation. By comparison, near-infrared spectroscopy (NIRS) presented better results than ATR-FTIR: prediction error ATR-FTIR 18% > prediction error NIRS 9%. Consequently, NIRS demonstrates great potential to be adopted as an in-line or on-line, non-destructive, and sustainable method for dairy and especially infant formula manufacturers.

Fast, direct and in situ monitoring of lipid oxidation in an oil-in-water emulsion by near infrared spectroscopy.

Lipid oxidation has implications on food, cosmetics and other fat containing products. Fatty acid autoxidation alters both the quality and safety of these products. Efficient and fast methods are needed to track lipid oxidation in complex systems. In this study, an oil-in-water emulsion (20% v/v of fish oil stabilized with high oleic sunflower lecithin) was subjected to iron-initiated oxidation. Conjugated dienes (CDs) were measured after fat extraction using a standardized method. Near infrared spectroscopy (NIRS) has been used to record chemical changes occurring during oxidation directly in the emulsion. Variations were noticed in different spectral regions. Partial least squares regression (PLSR) revealed correlations between conjugated diene values and NIRS spectra. High coefficients of determination (R2 = 0.967 and 0.996) were found for calibration and prediction respectively. The CD value was predicted from NIRS spectra with an error of 7.26 mmol eq. LH kg-1 oil (7.8% error). Limits of detection (LOD) and quantification (LOQ) of 4.65 and 15.5 mmol eq. LH kg-1 oil were estimated. NIRS is a rapid and simple method for measuring lipid oxidation (CD value) in an emulsion without prior fat extraction. NIRS can replace the reference methods that use hazardous solvents and consume time. Therefore, NIRS enables in-line monitoring for process and quality control.

Lemon Juice, Sesame Paste, and Autoclaving Influence Iron Bioavailability of Hummus: Assessment by an In Vitro Digestion/Caco-2 Cell Model.

Hummus, an iron-containing plant-based dish mainly made from chickpea purée, tahini, lemon juice and garlic, could be a valuable source of iron when bioavailable. Since the processing and formulation of food influence iron bioavailability, the present study investigated for the first time, their effects on hummus. Firstly, iron bioaccessibility was assessed on eight samples (prepared according to the screening Hadamard matrix) by in vitro digestion preceding iron dialysis. Then, iron bioavailability of four selected samples was estimated by the in vitro digestion/Caco-2 cell model. Total and dialyzable iron were determined by the atomic absorption spectrometry and ferritin formation was determined using an ELISA kit. Only autoclaving, among other processes, had a significant effect on iron bioaccessibility (+9.5, p < 0.05). Lemon juice had the highest positive effect (+15.9, p < 0.05). Consequently, the effect of its acidic components were investigated based on a full factorial 23 experimental design; no significant difference was detected. Garlic's effect was not significant, but tahini's effect was negative (-8.9, p < 0.05). Despite the latter, hummus had a higher iron bioavailability than only cooked chickpeas (30.4 and 7.23 ng ferritin/mg protein, respectively). In conclusion, hummus may be a promising source of iron; further in vivo studies are needed for confirmation.

A New pH-Dependent Macrocyclic Rhodamine B-Based Fluorescent Probe for Copper Detection in White Wine.

For efficiently measuring copper (II) ions in the acidic media of white wine, a new chemosensor based on rhodamine B coupled to a tetraazamacrocyclic ring (13aneN4CH2NH2) was designed and synthesized by a one-pot reaction using ethanol as a green solvent. The obtained chemosensor was characterized via NMR, UV and fluorescent spectra. It was marked with no color emission under neutral pH conditions, with a pink color emission under acidic conditions, and a magenta color emission under acidic conditions where copper (II) ions were present. The sensitivity towards copper (II) ions was tested and verified over Ca2+, Ag+, Zn2+, Mg2+, Co2+, Ni2+, Fe2+, Pb2+, Cd2+, Fe3+, and Mn2+, with a detection limit of 4.38 × 10-8 M in the fluorescence spectrum.

Molecularly imprinted sol-gel polymers for the analysis of iprodione fungicide in wine: Synthesis in green solvent.

Iprodione is a fungicide widely used in viticulture in most agricultural countries. It was banned recently in the European community because of its carcinogenic and endocrine disrupting characters. In this work, a cheap analytical method able to monitor iprodione in a white wine was developed. Molecularly imprinted sol-gel polymers (MIS) specific to iprodione and using green solvents were synthesized. An experimental design having the following factors (solvent volume and crosslinker quantity) was used to prepare an optimal MIS. In terms of selectivity, the optimal MIS showed the best partition coefficient towards iprodione in a white wine containing four other competing fungicides (procymidone, pyrimethanil, azoxystrobin and iprovalicarb). A solid phase extraction method using the optimal MIS was optimized and applied to analyse iprodione in a white wine. Low detection and quantification limits were reached 11.7 and 39.1 µg/L respectively.

Fast and direct analysis of oxidation levels of oil-in-water emulsions using ATR-FTIR.

Oxidation of omega-3 fatty acids is a major limitation on its enrichment in food and beverages. An efficient and simple method to monitor lipid oxidation in complex systems is essential to limit lipid oxidation during formulation and processing. Fish oil-in-water emulsions (20% v/v) were exposed to iron or free radical initiated oxidation. Conjugated dienes (CDs) were rapidly measured using a previously developed fat extraction method. Fourier transform infrared (FTIR) spectroscopy has been used to directly record chemical changes occurring during oxidation. Variations were noticed in different spectral regions despite the presence of broad water bands near 3400 and 1640 cm-1. Partial least squares regression (PLSR) revealed correlations between CD values and full FTIR spectra (4000-600 cm-1), and different spectral regions (e.g., 1800-1500 cm-1, 1500-900 cm-1). These correlations confirm that FTIR spectroscopy is a rapid and simple method for measuring lipid oxidation in complex foods without prior fat extraction.

Impact of functional properties and release kinetics on antioxidant activity of biopolymer active films and coatings.

This work deals with the study of the release kinetics of some natural antioxidants (ferulic acid, caffeic acid and tyrosol) from chitosan-fish gelatin edible films immersed ethanol at 96%, as well as the kinetics of their antioxidant activity using the DPPH assay. The aim was to determine how film functional properties influence the release kinetic and antioxidant activity. The addition of antioxidants to chitosan-fish gelatin matrix decreased the water vapour permeability by more than 30%. The tensile strength (TS) increased up to 50% after the incorporation of antioxidants. Some molecular interactions between polymer chains and antioxidants were confirmed by FTIR where spectra displayed a shift of the amide-III peak. Films containing caffeic acid or a caffeic-ferulic acid mixture exhibited the highest radical scavenging activity, leading to a 90% antioxidant activity at equilibrium but the release rate controlled the efficacy of the system.

Substitution of carcinogenic solvent dichloromethane for the extraction of volatile compounds in a fat-free model food system.

Dichloromethane is known as a very efficient solvent, but, as other halogenated solvents, is recognized as a hazardous product (CMR substance). The objective of the present work is to propose substitution solvent for the extraction of volatile compounds. The most important physico-chemical parameters in the choice of an appropriate extraction solvent of volatile compounds are reviewed. Various solvents are selected on this basis and on their hazard characteristics. The selected solvents, safer than dichloromethane, are compared using the extraction efficiency of volatile compounds from a model food product able to interact with volatile compounds. Volatile compounds with different hydrophobicity are used. High extraction yields were positively correlated with high boiling points and high Log Kow values of volatile compounds. Mixtures of solvents such as azeotrope propan-2-one/cyclopentane, azeotrope ethyl acetate/ethanol, and mixture ethyl acetate/ethanol (3:1, v/v) gave higher extraction yields than those obtained with dichloromethane.

Binding characteristics of molecularly imprinted polymers based on fungicides in hydroalcoholic media.

An iprodione-imprinted polymer was prepared by copolymerization of methacrylamide and ethylene glycol dimethacrylate using a noncovalent imprinting approach. Methacrylamide was chosen using molecular dynamics simulations. To concentrate iprodione from hydro-alcoholic solutions, batch sorption of iprodione on the imprinted polymer were conducted. The equilibrium time for iprodione sorption is 20 min, and the corresponding kinetic mechanism follows the pseudo-second order indicating a strong interaction between iprodione and the imprinted polymer. Langmuir, Freundlich, and Dubinin-Radushkevich models were used to fit the isotherm of iprodione sorption. The imprinted polymer was found to be more efficient than the nonimprinted polymer for the uptake of iprodione, as revealed by its higher adsorption energy, affinity, and capacity. Finally, a selectivity study was conducted on the imprinted and the nonimprinted polymers to sorb three fungicides. It shows that the imprinted polymer could be used as a preconcentration phase in a multiresidue analysis of fungicides in hydroalcoholic medium.

Silica-coated calcium pectinate beads for colonic drug delivery.

The aim of this work is to develop novel organic-inorganic hybrid beads for colonic drug delivery. For this purpose, calcium pectinate beads with theophylline are prepared by a cross-linking reaction between amidated low-methoxyl pectin and calcium ions. The beads are then covered with silica, starting from tetraethyoxysilane (TEOS), by a sol-gel process. The influence of TEOS concentration (0.25, 0.50, 0.75 and 1.00 M) during the process is studied in order to modulate the thickness of the silica layer around the pectinate beads and thus to control the drug release. The interactions between the silica coating and the organic beads are weak according to the physicochemical characterizations. A good correlation between physicochemical and in-vitro dissolution tests is observed. At concentrations of TEOS beyond 0.25 M, the silica layer is thick enough to act as a barrier to water uptake and to reduce the swelling ratio of the beads. The drug release is also delayed. Silica-coated pectinate beads are promising candidates for sustained drug delivery systems.