Encapsulation of food grade antioxidant in natural biopolymer by electrospinning technique: A physicochemical study based on zein–gallic acid system

Gallic acid was successfully incorporated into zein ultra-fine fibres at different loading amount (5%, 10% and 20%) in order to develop an encapsulating technology for functional ingredient delivery using electrospinning. The produced fibres exhibit diameters ranging from 327 to 387 nm. The physical and thermal properties of encapsulated gallic acid were determined by X-ray diffraction (XRD) and differential scanning calorimetry (DSC); and the interaction between gallic acid and zein was attested by attenuated total reflection-Fourier transform infrared (ATR-FTIR). Thermogravimetric analysis (TGA) demonstrated a different thermal stability of the fabricated complex before and after the gallic acid incorporation. Lastly, the 1,1′-diphenyl-2-picrylhydrazyl (DPPH) assay showed that the gallic acid had retained its antioxidant activity after incorporation in zein electrospun fibres. Overall, electrospinning technique had shown promising results as an efficient and effective method for the preparation of sub-micron structured encapsulated functional ingredient that may find uses in food industry.     

Biological activities of Maillard reaction products (MRPs) in a sugar–amino acid model system

The various biological activities of Maillard reaction products (MRPs) from sugar (fructose and glucose) and 20 amino acid model systems were evaluated. Colour development, in vitro antioxidant, α-glucosidase inhibitory, antihypertensive, and antiproliferative activities of aqueous solutions of MRPs produced by heating at 130 °C for 2 h were measured. The fructose–amino acid mixture showed higher UV-absorbance and browning intensity than the glucose–amino acid mixture. The fructose–amino acid model MRPs showed higher DPPH and ABTS radical scavenging and ACE inhibitory activities than the glucose–amino acid model MRPs. The α-glucosidase inhibitory effect of MRPs derived from fructose– and glucose–tyrosine showed higher α-glucosidase inhibitory activity than that of other MRPs. Sugar–amino acid model MRPs inhibited the growth of HCT116 colon cancer cell in a dose-dependent manner (from 0.5 to 1.5 mg/ml). Glucose MRPs showed slightly higher antiproliferative activity than fructose MRPs. In particular, sugar–tryptophan and –tyrosine MRPs exerted higher biological activities than the other MRPs.     

Stability of antioxidants in an apple polyphenol–milk model system

The stability of antioxidants in an apple polyphenol–milk model system was examined. The model system consisted of skim milk fortified with pH-neutralised apple polyphenols (AP, 0–200 mg per 100 ml milk), with or without ascorbic acid (100 mg per 100 ml milk). Physical and chemical changes were evaluated after thermal treatment (120 °C, 5 min) and oxidative storage (20 °C and 38 °C, up to 12 weeks). Antioxidant capacity was determined using both oxygen radical absorbance capacity (ORAC) assay and ferric reducing antioxidant power (FRAP) assay. Significant antioxidant capacity was detected in the presence of milk. Antioxidant capacity was retained during thermal treatment but decreased slowly during storage.     

Fabrication of poly(vinylidenefluoride‐co‐hexafluoropropylene) nanofiber yarns by conjugate electrospinning

Conventional electrospinning is an efficient method to fabricate polymer nanofibers which are usually collected as non‐woven mats. Recently, in order to fabricate a nanofiber yarn, conjugate electrospinning has been developed using coupled spinnerets applied with two high electrical voltages of opposite polarities In this paper, poly(vinylidenefluoride‐co‐hexafluoropropylene) (PVDF‐HFP) nanofiber yarns are prepared by conjugate electrospinning. The effects of the concentration and delivery rate of polymer solution and the distance between coupled spinnerets on the structure of PVDF‐HFP nanofiber yarns are investigated. The structure of the nanofiber yarns is observed by scanning electron microscopy (SEM). The mechanical properties of the nanofiber yarns are measured by electronic fiber strength tester. The results show that the PVDF‐HFP nanofiber yarn consists of a large number of nanofibers aligned well along the longitudinal axis of the yarn, and the nanofibers have diameters ranging from several hundred nanometers to a few microns. The diameter of nanofibers in yarns increases with the increase in the polymer concentration, which significantly affects the structure of nanofiber yarns. The PVDF‐HFP nanofiber yarn electrospun from the polymer solution with a concentration of 45% has the highest tensile strength of 0.25 cN/dtex and an elongation of 180.13%.     

Sweetness–texture interactions in model dairy desserts: effect of sucrose concentration and the carrageenan type

Sweetness–texture interactions were investigated in model dairy desserts varying in both sucrose concentration and carrageenan composition (κ-, ι-, λ-carrageenans or an equal-weight mixture of the three). Nineteen panellists evaluated sweetness and five oral texture attributes while instrumental texture was characterised by penetrometry. For each carrageenan composition, sweetness significantly increased with sucrose. Rheological profiles or oral texture attributes allowed to distinguish four matrices. Sweetness–texture interactions were observed but no common rule was applied. On the one hand, firmness of κ-carrageenan desserts, springiness and firmness of ι-carrageenan desserts, unctuousness of λ-carrageenan desserts and brittleness and unctuousness of mix-carrageenan ones increased with sucrose concentration. These changes can be partly attributed to changes in the mechanical profiles. On the other hand, variation of carrageenan composition modified sweetness assessment at higher concentrations, λ-carrageenan desserts being the sweetest and ι-carrageenan desserts the least sweet. A model, which considered carrageenan composition, sucrose concentration and their interactions, was established to relate sweetness and composition of the desserts.     

Evaluation of Dispersive Liquid–Liquid Microextraction–HPLC–UV for Determination of Deoxynivalenol (DON) in Wheat Flour

A fast and simple method for the extraction of deoxynivalenol (DON) from wheat flour using dispersive liquid–liquid microextraction (DLLME) followed by high-performance liquid chromatography–UV detection has been developed and compared with immunoaffinity column cleanup (IAC) process. The influence of several important parameters on the extraction efficacy was studied. Under optimized conditions, a linear calibration curve was obtained in the range of 50–1,000 μg/L. Average recoveries of DON from spiked wheat samples at levels of 500 μg/kg for DLLME and IAC ranged from 72.9?±?1.6 and 85.5?±?3.1, respectively. A good correlation was found for spiked samples between DLLME and IAC methods. The limit of detection was 125 and 50 μg/kg for DLLME and IAC method, respectively. Advantages of DLLME method with respect to the IAC have been pointed out.     

Mycotoxin contamination of foods in Southern Africa: A 10-year review (2007–2016)

Major staple foods in Southern Africa are prone to mycotoxin contamination, posing health risks to consumers and consequent economic losses. Regional climatic zones favor the growth of one or more main mycotoxin producing fungi, Aspergillus, Fusarium and Penicillium. Aflatoxin contamination is mainly reported in maize, peanuts and their products, fumonisin contamination in maize and maize products and patulin in apple juice. Lack of awareness of occurrence and risks of mycotoxins, poor agricultural practices and undiversified diets predispose populations to dietary mycotoxin exposure. Due to a scarcity of reports in Southern Africa, reviews on mycotoxin contamination of foods in Africa have mainly focused on Central, Eastern and Western Africa. However, over the last decade, a substantial number of reports of dietary mycotoxins in South Africa have been documented, with fewer reports documented in Botswana, Lesotho, Malawi, Mozambique, Zambia and Zimbabwe. Despite the reported high dietary levels of mycotoxins, legislation for their control is absent in most countries in the region. This review presents an up-to-date documentation of the epidemiology of mycotoxins in agricultural food commodities and discusses the implications on public health, current and recommended mitigation strategies, legislation, and challenges of mycotoxin research in Southern Africa.     

Formation of Pb(III) intermediates in the electrochemically controlled Pb(II)/PbO₂ system

The formation of lead dioxide PbO(2), an important corrosion product in drinking water distribution systems with lead-bearing plumbing materials, has been hypothesized to involve Pb(III) intermediates, but their nature and formation mechanisms remain unexplored. This study employed the electrochemical (EC) method of rotating ring disk electrode (RRDE) and quantum chemical (QC) simulations to examine the generation of intermediates produced during the oxidation of Pb(II) to PbO(2). RRDE data demonstrate that PbO(2) deposition and reduction involves at least two intermediates. One of them is a soluble Pb(III) species that undergoes further transformations to yield immobilized PbO(2) nanoparticles. The formation of this intermediate in EC system is mediated by hydroxyl radicals (OH(?)), as was evidenced by the suppression of intermediates formation in the presence of the OH(?) scavenger para-chlorobenzoic acid. QC simulations confirmed that the oxidation of Pb(II) by OH(?) proceeds via Pb(III) species. These results show that Pb(III) intermediates play an important role in the reactions determining transitions between Pb(II) and Pb(IV) species and could impact lead release in drinking water.     

Analysis of furan in coffee of different provenance by head-space solid phase microextraction gas chromatography–mass spectrometry: effect of brewing procedures

A simple, sensitive and accurate method for the analysis of furan in roasted coffee has been used based on headspace–solid-phase micro-extraction (HS–SPME) coupled to gas chromatography–mass spectrometry (GC–MS). The extraction was performed using 75-µm carboxen/polydimethylsiloxane fiber. Ionic strength, extraction time and temperature, and desorption time were assessed as the most important parameters affecting the HS–SPME procedure and d ₄-furan was used as the internal standard. The linearity range was in the range 0.0075–0.486 ng g^?1; the LOD and LOQ calculated using the signal-to-noise ratio approach were 0.002 and 0.006 ng g^?1, respectively. The inter- and intra-day precision was 8 and 10%, respectively. The concentration of furan found in batches of roasted coffee powder different producing countries ranged from 57.3 to 587.3 ng g^?1. The mean reduction in furan levels observed when brewing coffee by either infusion, using a moka pot or an expresso machine was 57, 67.5 and 63.3%, respectively.     

Formation of heterocyclic amine–amino acid adducts by heating in a model system

Although mutagenic and carcinogenic heterocyclic amines (HCAs) are known to be formed in cooked meat and fish, human HCA exposure and carcinogenic risk have not been elucidated in sufficient detail. In this work, we investigated the formations of HCA–amino acid adducts in a model system by using a liquid chromatography–mass spectrometry to elucidate another source of human HCA exposure. The 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) adduct with glycine was formed easily by heating at 200 °C within 5 min, which is probably based on the dehydration condensation of the amino group of PhIP and carboxyl group of glycine. PhIP and other HCAs such as 2-amino-3-methyl-3H-imidazo[4,5-f]quinolone, 2-amino-3,8-dimethylimidazo[4,5-f]-quinoxaline and 3-amino-1,4-dimethyl-5H-pyrido[3,4-b]indole, also bound with various amino acids by heating. Among these amino acids, proline tends to form adducts with HCAs, but serine, cysteine and lysine hardly bound with HCAs. These results provided a basic understanding of the formation of HCA adducts with amino acids during cooking.     

Adsorption of rutin onto a food-grade styrene–divinylbenzene copolymer in a model system

Adsorption of quercetin-3-O-rutinoside (rutin) onto Amberlite^® XAD 16HP was studied applying a modified D-optimal design. Temperature, pH value, rutin concentration and resin amount were studied as independent factors determining rutin adsorption. Using the mathematical model resulting from the analysis of the D-optimal design the optimal conditions for rutin adsorption onto the styrene–divinylbenzene copolymer were determined. Furthermore, the model equation was successfully applied to calculate the Langmuir and Freundlich isotherm parameters of this particular solute–sorbent system. In addition, the data obtained from the D-optimal design allowed the calculation of ΔG, ΔH and ΔS for the adsorption process. The results presented in this study are of utmost importance for a better understanding of adsorption phenomena. The more detailed knowledge of such sorbent systems is required to improve the cost-effectiveness of industrial processes for the recovery of secondary plant metabolites, such as polyphenols, based on resin adsorption technology.     

Rheological evaluation of gelatin–xanthan gum system with high levels of co-solutes in the rubber-to-glass transition region

Effects of moisture content, xanthan gum (XG) addition, and glucose syrup (GS):sucrose ratio on the gelation of gelatin-XG systems with high levels of co-solutes were investigated in the rubbery and the glass transition regions. Frequency sweep tests were performed between 0.1 and 100 rad and the storage (G′) and loss (G″) moduli of the system were measured in the temperature range of 60 to −15 °C. The onset of glass transition region increased with decreasing moisture content. The time–temperature superposition yielded master curves of G′ and G″ as a function of timescale of measurement. G″ and G″ were superimposed with the horizontal shift factor a_T, which was temperature dependent according to the Williams–Landel–Ferry (WLF) equation. Glass transition temperature (T_g) of the samples were determined by dynamic mechanical analysis (DMA) from the peak of tan δ. T_g decreased with XG addition. The energy of vitrification of samples with XG increased compared to samples containing only gelatin. Relaxation spectra of the samples were calculated from rheological measurements using the first and second approximations. The Rouse theory was more closely followed with the second approximation.     

Trends in Contact Lens Prescribing in Japan (2003–2016)

Purpose

To review contact lens prescribing trends in Japan between 2003 and 2016.