Effect of iron chelates on oil–water interface,stabilized by milk proteins: The role of phosphate groups and pH. Prediction of iron transfer from aqueous phase toward fat globule surface by changes of interfacial properties

Iron incorporated into food systems induces oxidation and precipitation. The consequences are reduced bioavailability and a functional modification of other food components such as proteins. The iron-chelates such as ferrous bisglycinate represent a possibility to avoid side effects, since the iron is protected. The aim of this study is to investigate the effects of iron-chelates compounds on the properties of an oil/water interface stabilized by caseinate or β-lacotoglobulin, under environmental conditions at 20 °C. Analyses were performed using dynamic drop tensiometry during 5000 s. The aqueous bulk phase is an imidazole/acetate buffer (0.1 M), containing 0.4 × 10⁻⁶ M protein, and 0.2 × 10^-6 9 M iron-chelates compounds. The results indicate that, under neutral conditions, the addition of some irons salts (NaFe-EDTA or Fe-bisglycinate) do not change the structure of the interface stabilized by a protein containing no phosphate groups (β-lactoglobulin). In the case of caseinate, NaFe-EDTA addition increases the lowering rate of surface tension at pH 6.5. On the contrary, the lowering rate of surface tension with caseinate is inhibited by Fe-bisglycinate at pH 6.5. Such an effect is not observed with β-lactoglobulin. The low transfer of irons ions from the bulk to the interface stabilized by β-lactoglobulin is confirmed by zetameter and FTIR measurements. These results indicate an effective strategy to follow for controlling the physical and chemical stability of an emulsion stabilized with proteins.     

Functional properties and health benefits of bioactive peptides derived from Spirulina: A review

Bioactive peptides represent specific sequences of amino acids that have biological activity with several health effects and potential applications, which can be obtained from diverse protein sources. Spirulina, the cyanobacterium known for its high protein content and therapeutic properties, has been investigated as a potential source of bioactive peptides. Some bioactive peptides derived from Spirulina are under study for their ability to offer specific health benefits, such as antimicrobial, antiallergic, antihypertensive, antitumor, and immunomodulatory properties. Bioactive peptide fractions from Spirulina biomass can be obtained through a series of operations, including cell lysis and protein extraction, enzymatic hydrolysis, potential bioactivity screening, fractionation, and purification. Potentially, Spirulina-derived peptide fractions can be applied as nutraceutical ingredients in foods and pharmaceuticals. This article reviews the functional properties and health benefits of bioactive peptides from Spirulina, and presents potential mechanisms by which bioactive components can be exploited in the development of novel foods with special health claims. In addition, this article describes recent developments in proteomics, bioactivity screening methods, and opportunities for designing future peptide-based foods.     

A review of varietal change in roots,tubers and bananas: consumer preferences and other drivers of adoption and implications for breeding

This review of the literature on varietal change in sub-Saharan Africa looks in detail at adoption of new varieties of bananas in Uganda, cassava in Nigeria, potato in Kenya, sweetpotato in Uganda and yams in Côte d’Ivoire. The review explored three hypotheses about drivers of varietal change. There was a strong confirmation for the hypothesis that insufficient priority given to consumer-preferred traits by breeding programmes contributes to the limited uptake of modern varieties (MVs) and low varietal turnover. Lack of evidence meant the second hypothesis of insufficient attention to understanding and responding to gender differences in consumer preferences for quality and post-harvest traits was unresolved. The evidence on the third hypothesis about the informal seed system contributing to slow uptake of MVs was mixed. In some cases, the informal system has contributed to rapid uptake of MVs, but often it appears to be a barrier with inconsistent varietal naming a major challenge.     

Evaluation of the effect of a novel membrane filtration system on the lifespan of frying oil

Frying oil has a limited lifetime which results in the disposal of approximately 67% of all used oil. The aim of this study is to determine the suitability of different membranes for purifying frying oil and investigate the application of continuous membrane filtration in a commercial deep fryer. Eleven different membranes were tested to assess their suitability for filtrating frying oil. A prototype continuous filtration system with an integrated membrane filter was developed for a deep fryer to assess the effect of continuous membrane filtration on oil degradation. The prototype was subjected to a frying test over 13 days and the results compared to those from a standard deep fryer. The prototype maintained total polar compounds (TPC) at an acceptable level of <12% and the oil remained light in colour even after more than 280 h of use, while TPC in the standard deep fryer rose to >27%.     

Serum concentrations of polyfluoroalkyl compounds in Faroese whale meat consumers

To learn the extent of human exposure to polyfluoroalkyl compounds (PFCs) in a remote fishing population, we measured, in Faroese children and pregnant women, the serum concentrations of nine PFCs, including perfluorooctane sulfonate (PFOS), perfluorooctanoate (PFOA), and perfluorononanoate (PFNA), by using online solid-phase extraction coupled to isotope dilution high-performance liquid chromatography-tandem mass spectrometry. The serum samples analyzed had been collected between 1993 and 2005 from 103 children 7 years of age, 79 of these children at 14 years of age, and from 12 pregnant women and their children 5 years later. PFOS was detected in all samples analyzed, and both PFOA and PFNA were detected in all but one of the samples. The concentrations found are comparable tothose reported elsewhere. Correlations between paired concentrations were poor. However, PFOS and PFNA concentrations correlated well with the frequency of pilotwhale dinners and with concentrations of mercury and polychlorinated biphenyls. One whale meal every two weeks increased the PFOS concentration in 14-year-olds by about 25% and PFNA by 50%. The high frequency of detection of most PFCs suggests widespread exposure in the Faroe Islands already by the early 1990s, with whale meat being an important source.     

Use of volatile compound metabolic signatures in poultry liver to back-trace dietary exposure to rapidly metabolized xenobiotics

The study investigated the feasibility of using volatile compound signatures of liver tissues in poultry to detect previous dietary exposure to different types of xenobiotic. Six groups of broiler chickens were fed a similar diet either noncontaminated or contaminated with polychlorinated dibenzo-p-dioxins/-furans (PCDD/Fs; 3.14 pg WHO-TEQ/g feed, 12% moisture), polychlorinated biphenyls (PCBs; 0.08 pg WHO-TEQ/g feed, 12% moisture), polybrominated diphenyl ethers (PBDEs; 1.63 ng/g feed, 12% moisture), polycyclic aromatic hydrocarbons (PAHs; 0.72 μg/g fresh matter), or coccidiostats (0.5 mg/g feed, fresh matter). Each chicken liver was analyzed by solid-phase microextraction - mass spectrometry (SPME-MS) for volatile compound metabolic signature and by gas chromatography - high resolution mass spectrometry (GC-HRMS), gas chromatography - tandem mass spectrometry (GC-MS/MS), and liquid chromatography - tandem mass spectrometry (LC-MS/MS) to quantify xenobiotic residues. Volatile compound signature evidenced a liver metabolic response to PAH although these rapidly metabolized xenobiotics are undetectable in this organ by the reference methods. Similarly, the volatile compound metabolic signature enabled to differentiate the noncontaminated chickens from those contaminated with PBDEs or coccidiostats. In contrast, no clear signature was pointed out for slowly metabolized compounds such as PCDD/Fs and PCBs although their residues were found in liver at 50.93 (±6.71) and 0.67 (±0.1) pg WHO-TEQ/g fat, respectively.     

Combined speciation analysis by X-ray absorption near-edge structure spectroscopy, ion chromatography, and solid-phase microextraction gas chromatography-mass spectrometry to evaluate biotreatment of concentrated selenium wastewaters

In this study we evaluate the potential of anaerobic granular sludge as an inoculum for the bioremediation of selenium-contaminated waters using species-specific analytical methods. Solid species formed by microbial reduction were investigated using X-ray absorption near-edge structure (XANES) spectroscopy at the selenium K-edge. Furthermore, dissolved selenium species were specifically determined by ion chromatography (IC) and solid-phase microextraction gas chromatography-mass spectrometry (SPME-GC-MS). Least-squares linear combination of the XANES spectra for samples incubated with the highest selenate/selenite concentrations (10(-3) M) show the predominance of elemental selenium and a Se(-I) selenide, such as ferroselite, the thermodynamically most stable iron selenide. In contrast, elemental selenium and Se(-II) selenides are the main species detected at the lower selenate/selenite concentrations. In each repeated fed batch incubation, most aqueous selenite anions were converted into solid selenium species, regardless of the type of electron donor used (acetate or H(2)/CO(2)) and the selenium concentration applied. On the other hand, at higher concentrations of selenate (10(-4) and 10(-3) M), significant amounts of the oxyanion remained unconverted after consecutive incubations. SPME-GC-MS demonstrated selenium alkylation with both electron donors investigated, as dimethyl selenide (DMSe) and dimethyl diselenide (DMDSe). Selenite was even more alkylated in the presence of H(2)/CO(2) (maximum 2156 μg of Se/L of DMSe + DMDSe) as compared to acetate (maximum 50 μg of Se/L). In contrast, selenate was less alkylated using both electron donors (maximum 166 and 3 μg of Se/L, respectively). The high alkylation potential for selenite limits its bioremediation in selenium laden waters involving H(2)/CO(2) as the electron donor despite the fact that nontoxic elemental selenium and thermodynamically stable metal selenide species are formed.     

Bacterial formation of tooeleite and mixed arsenic(III) or arsenic(V)-iron(III) gels in the Carnoulès acid mine drainage,France. A XANES,XRD, and SEM study

The oxidation of Fe(II) in acid mine drainage (AMD) leads to the precipitation of Fe(III) compounds which may incorporate toxic elements, such as arsenic (As), within their structure or adsorb them at their surface, thus limiting their mobility. The present work provides evidence for spatial and seasonal variations of microbial activity that influence arsenite oxidation and As immobilization in the heavily contaminated AMD from the Carnoulès mine, Gard, France ([As III] = 80 to 280 mg x L(-1) in the acidic spring draining the waste-pile). In the first tens of meters of the AMD, the rapid oxidation of Fe(II) leads to the coprecipitation of large amounts of As with Fe(III) in bacterial mats. XRD, XANES, and SEM analyses of sediments and stromatolite samples revealed the unusual formation of As(III)-rich compounds, especially nanocrystalline tooeleite, Fe6(AsO3)4(SO4)(OH)4 x 4H2O, a rare ferric arsenite sulfate oxy-hydroxide mineral, together with XRD-amorphous mixed As(III)/As(V)-Fe(III) oxy-hydroxide compounds. In the wet season, the suspended sediments of the upstream zone essentially consist of tooeleite associated with am-As(III)-Fe(III) oxy-hydroxides, while am-As(V)-Fe(III) oxy-hydroxides, having As:Fe molar ratios as high as 0.6-0.8, dominate in the dry season. Comparing natural and bioassay samples revealed that the formation of As(III)-rich compounds in the wet season may be related to the metabolic activity of bacterial strains able to oxidize Fe(II) but not As(III). One of these strains, having an Acidithiobacillus ferrooxidans genotype, has been isolated from the Carnoulès AMD. In contrast, the formation of As(V)-rich compounds in the dry season can be related to both biotic and abiotic oxidation of As(III) to As(V). Some Thiomonas strains isolated from the Carnoulès AMD were shown to be able to catalyze the oxidation of As(III) to As(V) in solution. Therefore, they can promote the formation of mixed As(V)-Fe(III) oxy-hydroxides, provided enough Fe(II) oxidizes. These results yield a better understanding of natural processes at this site and may help in designing efficient As-removal processes.     

Influence of the modelling approach on the estimation of the minimum temperature for growth in Belehrádek-type models

This paper compares three different approaches for describing the growth rate dependence on sub-optimal temperatures {e.g., the square-root model described by Ratkowsky et al. (1982. J. Bacteriol. 154, 1222–1226): √μ=b.(T−T_min1) or μ=b². (T−T_min1)², the model originally found by Belehrádek (1926a. Nature11, 117–118): μ=a. (T−T₀)^αand a dimensionless analysis described previously, (Dantigny 1998. J. Ind. Microbiol. Biotechnol.21, 215–218.):

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Data sets, growth rate vs temperature, have been taken from the literature for various organisms (e.g. Lactobacillus plantarum, Yersinia enterolitica and Acinetobacter).Firstly, this paper analyses the effect of using dimensionless (e.g. T_dimand μ_dim) or natural variables (e.g. T and μ) on the estimation of the minimum temperature for growth (e.g. T₀and T_min) and the α value. Secondly, the Belehrádek model is compared to the square-root model by using the natural variables. It has been demonstrated that the use of the square-root model leads to an under-estimation of the minimum temperature for growth when the α -value is significantly less than 2. In such a case, it has been highlighted that the dimensionless approach provides a closer estimation of the experimental minimum temperature for growth than the square-root model.