Determination of clothianidin in food products by using an automated system with photochemically induced fluorescence detection

A flow-through system based on the integration of solid-phase spectroscopic detection implemented with photochemically induced fluorescence (PIF) is proposed for the determination of clothianidin (a non-fluorescent neonicotinoid insecticide) through a multicommutated method. The pesticide is injected into the carrier stream (0.015 mol L⁻¹C₂H₄O₂/NaC₂H₃O₂, pH = 5.0) and flows towards a homemade photoreactor, which consists of a PTFE tubing loosely coiled around a low-pressure mercury lamp (15W). After the photochemical reaction of clothianidin, the generated fluorescent photoproduct is transported to a flow cell packed with Sephadex-SP C-25 where it is retained and monitored (λ_ex = 357 nm/λ_em = 418 nm). The method presents a detection limit of 1.5 ng mL⁻¹, a sample throughput of 23 h⁻¹ and inter-day relative standard deviation lower than 3%. The described system has been satisfactorily applied to the determination of clothianidin in samples of drinking water, rice and honey. Taking into account that the maximum residue limit specified in the Codex Alimentarius Commission for rice grains is 0.5 mg kg⁻¹, recovery experiments have been carried out for clothianidin concentrations in the 0.3-10.0 mg kg⁻¹ range.     

Changes in bioactive composition of fresh-cut strawberries stored under superatmospheric oxygen,low-oxygen or passive atmospheres

The effect of different modified atmosphere packaging conditions (2.5 kPa O₂ + 7 kPa CO₂, 10 kPa O₂ + 5 kPa CO₂, 21 kPa O₂, 60 kPa O₂ and 80 kPa O₂) on the antioxidant properties of fresh-cut strawberries was investigated. Changes in phenolic acids, flavonoids (anthocyanins and flavonols), vitamin C and antioxidant capacity were analyzed for 21 days at 4 °C. O₂, and CO₂ package headspace concentrations were also evaluated. The initial quercetin content was maintained for 11–14 days regardless of the initial in-package atmospheres, but then it was dramatically enhanced in the strawberries stored at ≥21 kPa O₂. High O₂ concentrations inside headspace packages promoted greater losses of phenolic acids (p-coumaric, hydroxybenzoic and ellagic acid) and vitamin C during the storage period compared to low O₂ levels. Anthocyanin content increased significantly beyond day 9 in strawberry wedges stored at ≤21 kPa O₂, whereas it was almost constant throughout the storage in fresh-cut strawberries at superatmospheric O₂ atmospheres. In general, low-O₂ and passive atmospheres best maintained the initial antioxidant capacity of fresh-cut strawberries through the cold storage. Therefore, 2.5 kPa O₂ + 7 kPa CO₂ atmospheres are proposed to prevent oxidation of the main antioxidant compounds in fresh-cut strawberries.     

Toxicity of the micropollutants Bisphenol A,Ciprofloxacin, Metoprolol and Sulfamethoxazole in water samples before and after the oxidative treatment

The amount of organic micropollutants detected in surface waters increases steadily. Common waste water treatment plants are not built to remove these substances. Thus there is a need for new technologies. A promising technology is the use of advanced oxidation processes through which organic micropollutants can be removed from waste water. However, the formation of oxidation by-products is likely and needs to be investigated since the by-products not only differ from their parent compounds in regard to their chemical and physical properties but they can also differ in toxicity. Therefore this study was designed to combine chemical and toxicological analyses of the advanced oxidation (O₃ [5 mg/L] or UV/H₂O₂ [Hg-LP lamp; 15 W; 1 g/L H₂O₂]) of waste water treatment plant effluents and pure water. Effluent samples from conventional activated sludge waste water treatment (mechanical treatment, activated sludge basin, and primary as well as secondary treatment steps) and high-purity deionized water (pure water) were spiked with Bisphenol A, Ciprofloxacin, Metoprolol or Sulfamethoxazole and treated with O₃ or UV/H₂O₂. For the toxicological analyses mammalian cells (CHO-9, T47D) were exposed to the water samples for 24 h and were tested for cytotoxicity (MTT Test), genotoxicity (Alkaline Comet Assay) and estrogenicity (ER Calux^®). The results indicate that the oxidative treatment (O₃ or UV/H₂O₂) of Bisphenol A, Metoprolol, Sulfamethoxazole or Ciprofloxacin in waste water did not result in toxic oxidation by-products, whereas the UV/H₂O₂ treatment of Bisphenol A and Ciprofloxacin in pure water resulted in by-products with cytotoxic but no estrogenic effects after 60 min.     

Antioxidant compounds and antioxidant activity in acerola (Malpighia emarginata DC.) fruits and derivatives

Acerola (Malpighia emarginata DC.) is a wild plant from Central America. This fruit is well known as an excellent food source of vitamin C, and it also contains phytochemicals such as carotenoids and polyphenols. The present work evaluates the antioxidant capacity of hydrophilic extracts of acerola pulps and juices by 2,2′-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), ORAC and 1,1-diphenyl-2-picrylhydrazyl (DPPH) methods. Antioxidant activity values obtained for acerola juice were higher than those reported for other fruit juices particularly rich in polyphenols such as strawberry, grape and apple juices, among others. Vitamin C, total phenol index (TPI), total anthocyanins and polyphenolic compounds by high performance liquid chromatography (HPLC), as main factors responsible for antioxidant activity, were determined. Contents in total ascorbic acid ranged from 6.32 to 9.20 g kg⁻¹ of pulp and 9.44 to 17.97 g L⁻¹ of juice. Five different polyphenolic compounds were identified in the samples by means of HPLC and diode-array detection: chlorogenic acid, (−)-epigallocatechin gallate, (−)-epicatechin, procyanidin B1 and rutin, being the two last predominant. By means of solid phase extraction (SPE) three soluble polyphenolic fractions (phenolic acids, anthocyanins and flavonoids) were separated from the different sample extracts, and their respective antioxidant activities calculated. Among them, phenolic acids are the main contributors to the antioxidant activity.     

Effects of soaking conditions on the antioxidant potentials of oolong tea

The antioxidant properties of water extracts of oolong tea (Commercial name: Fenghuangdancong) prepared using different soaking temperatures and times were investigated. The yield of powdered extract ranged from 6.7% at 80 °C for 3 min soaking to 22.7% at 100 °C for 10-min soaking. Oolong tea extracts reduced peroxidation of peanut oil and delayed the time of POV20 (peroxide value). Among these soaking treatments, soaking for 10 min in 100 °C water produced extracts with the greatest ability to inhibit the peroxidation of peanut oil. As well, the SC50 (scavenging-percentage) of the α, α-diphenyl-β-picrylhydrazyl radical (DPPH radical) was 0.119 mL of oolong tea extract using 3-min soaking at 100 °C, which is closed to the SC50 of 0.109 mL (2 mg/mL) for vitamin C. The DPPH radical scavenging activity of oolong tea extracts increased with increasing temperature of the soaking water indicating greater extraction of antioxidant compounds. In addition, inhibition of oxidation of peanut oil and DPPH radical scavenging activity by water extract of oolong tea was associated with polyphenol concentrations. Sensory assessment, found that the water extract of oolong tea using 3-min soaking at 95 °C had the strongest aroma and sweetness attributes.     

Radical scavenging,antioxidant and metal chelating activities of Annona cherimola Mill. (cherimoya) peel and pulp in relation to their total phenolic and total flavonoid contents

This study aimed to evaluate the total phenolic and flavonoid content, radical scavenging activity (by DPPH and ABTS tests) and antioxidant capacity (by β-carotene bleaching test) of Annona cherimola (cherimoya) fruits cultivated in Italy for human consumption. The metal chelating activity and ferric reducing power were also determined. A. cherimola peel and pulp were characterized by a total phenolic content of 14.6 and 12.6 mg chlorogenic acid equivalents/100 g fresh weight, respectively. A similar trend was observed with flavonoid content. Both extracts exhibited high antioxidant activity through different mechanisms of action. In particular, peel extract demonstrated the strongest free radical scavenging activity with an IC₅₀ value of 57.7 μg/mL. The same extract was more effective in preventing β-carotene oxidation (IC₅₀ value of 63.5 μg/mL after 60 min) and showed higher chelating ability (IC₅₀ value of 79.6 μg/mL) than pulp extract. This work demonstrated the high quality of cherimoya fruits cultivated in Italy, and recommends the peel of this fruit product that may be of interest from a functional point of view as a major source of natural antioxidants.     

Identification and quantification of phenolic compounds responsible for the antioxidant activity of sweet potatoes with different flesh colours using high performance thin layer chromatography (HPTLC)

The objectives of the present study were to develop a simple high performance thin layer chromatography (HPTLC)-based protocol: (i) to allow high-throughput profiling of phenolic compounds of microwaved roots from 295 sweet potato varieties and breeding lines, (ii) to quantify the content of anthocyanins and caffeoylquinic acid (CQA) derivatives, and (iii) to determine their respective contributions to the antioxidant activity of sweet potato methanolic extracts using the DPPH test. Analysed accessions were separated into three groups: white-fleshed (n = 100), orange-fleshed (n = 64) and purple-fleshed (n = 131). Purple-fleshed accessions presented the highest mean CQA content. After DPPH treatment and transmittance scanning of the plate at 517 nm, the most active free radical scavengers were found to be the four CQAs (CGA, 3,4-, 4,5- and 3,5-diCQA) while the anthocyanins were found to be less active. The total antioxidant capacity of the sweet potato methanolic extracts was mostly linked to total CQAs content. This method can now be used for fast routine analysis and selection of sweet potato breeding clones.     

Determination of taxifolin in Polygonum orientale and study on its antioxidant activity

A high-performance liquid chromatographic method was developed to determine taxifolin in Polygonum orientale. The chromatographic separation was performed on a Lichrospher ODS column. The mobile phase consisted of CH₃OH–0.3%CH₃COOH (35:65, v/v) with a flow-rate of 0.8 mL/min. The chromatographic peak area was linear to the concentration of taxifolin in the range of 5.0–100 μg/mL with a detection limit of 0.23 μg/mL. Good recovery results were also obtained with the range of 97.4–101.2%. In addition, radical scavenging capacity of taxifolin was studied by means of 1,1-diphenylpicrylhydrazyl free radical. The IC₅₀ value was 4.11 μmol/L, which indicated that taxifolin had a very potent antioxidant activity.     

The synthesis,structure and activity evaluation of pyrogallol and catechol derivatives as Helicobacter pylori urease inhibitors

Some pyrogallol and catechol derivatives were synthesized, and their urease inhibitory activity was evaluated by using acetohydroxamic acid (AHA), a well known Helicobacter pylori urease inhibitor, as positive control. The assay results indicate that many compounds have showed potential inhibitory activity against H. pylori urease. 4-(4-Hydroxyphenethyl)phen-1,2-diol (2a) was found to be the most potent urease inhibitor with IC₅₀s of 1.5 ± 0.2 μM for extracted fraction and 4.2 ± 0.3 μM for intact cell, at least 10 times and 20 times lower than those of AHA (IC₅₀ of 17.2 ± 0.9 μM, 100.6 ± 13 μM), respectively. This finding indicate that 2a would be a potential urease inhibitor deserves further research. Molecular dockings of 2a into H. pylori urease active site were performed for understanding the good activity observed.     

A questionnaire approach to measuring the relative reinforcing efficacy of snack foods

Behavioral choice theory and laboratory choice paradigms can provide a framework to understand the reinforcing efficacy or reinforcing value of food. Reinforcing efficacy is measured in the laboratory by assessing how much effort one will engage in to gain access to food as the amount of work progressively increases. However, this method to establish demand curves as estimates of reinforcer efficacy is time consuming and limits the number of reinforcers that can be tested. The general aim of this study was to compare the reinforcing efficacy of snack foods using a behavioral task that requires subjects to respond to gain access to portions of food (LAB task) with a questionnaire version of a purchasing task designed to determine demand curves (QUES task) in nonobese and obese adults (n = 24). Results showed correlations between the maximal amount of money that individuals were willing to spend for food (QUES O_max) and the maximal amount of responses made on the highest reinforcement schedule completed (LAB O_max) (r = 0.45, p < 0.05), and between BMI and the LAB O_max (r = 0.43, p < 0.05) and the QUES O_max (r = 0.52, p < 0.05). The study suggests the questionnaire provides valid measures of reinforcing efficacy that can be used in place of or in conjunction with traditional laboratory paradigms to establish demand curves that describe the behavioral maintaining properties of food.     

Heat-assisted slurry sampling GFAAS method for determination of lead in food standard reference materials

A valid method based on heat-assisted slurry sampling graphic furnace atomic absorption spectrometry (HASS-GFAAS) was developed for the accurate determination of trace Pb in food standard reference materials (SRMs). The HASS technique significantly improved Pb recovery and precision compared to conventional slurry sampling techniques. The optimized HASS procedure was performed as follows: first, the sample (particle size ≤ 150 μm) was diluted with 0.05% (v/v) Triton X-100 containing 2% HNO₃ and 1% H₂O₂ followed by heating for 20 min at 120 °C on a heating block. Next, the obtained slurry was sonicated in an autosampler cup, and finally, the slurry was introduced into a graphite tube and analyzed by the GFAAS with a Pb electrodeless discharge lamp (EDL). Calibration with aqueous standard solutions was used for Pb determination in food samples. The characteristic mass and limit of detection for Pb based on the integrated absorbance for a 2% (m/v) sample were 12 ± 0.6 pg and 0.003 mg kg⁻¹, respectively. The accuracy (95.1–102% recovery) and good precision (0.1–3.6%) of this procedure are illustrated by the results obtained for the 12 food reference materials. The proposed method is suitable for determination of trace Pb in solid food samples.     

Inactivation of rabies virus by hydrogen peroxide

Development of safe and protective vaccines against infectious pathogens remains a challenge. Inactivation of rabies virus is a critical step in the production of vaccines and other research reagents. Beta-propiolactone (βPL); the currently used inactivating agent for rabies virus is expensive and proved to be carcinogenic in animals. This study aimed to investigate the ability of hydrogen peroxide (H₂O₂) to irreversibly inactivate rabies virus without affecting its antigenicity and immunogenicity in pursuit of finding safe, effective and inexpensive alternative inactivating agents. H₂O₂ 3% rapidly inactivated a Vero cell adapted fixed rabies virus strain designated as FRV/K within 2 h of exposure without affecting its antigenicity or immunogenicity. No residual infectious virus was detected and the H₂O₂-inactivated vaccine proved to be safe and effective when compared with the same virus harvest inactivated with the classical inactivating agent βPL. Mice immunized with H₂O₂-inactivated rabies virus produced sufficient level of antibodies and were protected when challenged with lethal CVS virus. These findings reinforce the idea that H₂O₂ can replace βPL as inactivating agent for rabies virus to reduce time and cost of inactivation process.     

Genetic identities and local inbreeding in pure diploid clones with homoplasic markers: SNPs may be misleading

Expected values for observed heterozygosity, genetic diversity, and inbreeding of individuals relative to inbreeding of the population (F_IS) are derived in the case of one locus displaying homoplasy with K possible allelic states (KAM model) in a clonal diploid population. Heterozygosity (H_O) and genetic diversity (H_S) are substantially affected by homoplasy as long as the number of alleles K ⩽ 10, while F_IS remains weakly affected in any case. Simulations suggest that in big populations, or in case of maximum homoplasy (K = 2), expected values can appear far from the observed ones because equilibrium takes too many generations to be reached at homoplasic markers in clonally propagating populations. This raises some concern on the use of SNPs, at least in clonal populations.     

Influence of ionizing radiation and conventional food processing treatments on the status of free radicals in lotus seeds: An ESR study

Electron spin resonance (ESR) spectroscopy was used to detect the free radicals that were naturally present in lotus seeds or that were formed after employing various food processing methods (e.g., irradiation, microwave roasting, pan frying, grinding or pounding) by placing small portions of lotus seed (seed coat and cotyledon) in KCl powder in ESR quartz tubes. Spectral analysis revealed the presence of an insignificant natural abundance of free radicals and showed a sharp and clear signal at g = 2.002, more prominent in seed coat. Exposure to gamma radiation (0–30 kGy, the recommended dose for quarantine purposes) resulted in a dose-dependent increase of signal intensity at g = 2.002 with the seed coat exhibiting the presence of a weak triplet (a_H = 3 mT) which can be used to authenticate irradiation treatments. Irradiated cotyledon at high doses (15 and 30 kGy) revealed significant reduction in ESR signals, attributed to an increase of free radical scavengers. Common food processing practices like microwave roasting, flame heating, grinding or pounding also generated free radicals. It is envisaged that results of the present study might be valuable for health conscious consumers who are interested in the status of free radicals in foodstuffs subjected to traditional or modern food-processing techniques.     

Aggregation and antigenicity of virus like particle in salt solution—A case study with hepatitis B surface antigen

The phenomenon of aggregation of virus-like particles (VLPs) in salt solution and the corresponding effect upon antigenicity was reported. Asymmetrical flow field-flow fractionation (AF4) combined with multi-angle laser light scattering (MALLS) was used to characterize the size and the aggregation behavior of hepatitis B surface antigen (HBsAg). The average diameter of HBsAg VLP was 22.8 ± 0.4 nm and it tended to aggregate in salt solution to form large particles and the antigenicity changed accordingly. In 0–4 M NaCl solution, part of HBsAg molecules aggregated rapidly into oligomeric particles (OP), whose diameter distributed from 25 to 40 nm, and the antigenicity slightly decreased about 10%. The aggregation reaction is reversible. After removing NaCl, both size and antigenicity could recover to normal level (92–96%). By contrast, the aggregation process is more complicated in (NH₄)₂SO₄ solution. Most of HBsAg particles aggregated into OP and further aggregated into polymeric particles (PP). The diameter of the PP could reach 40 to 140 nm. The concentration of (NH₄)₂SO₄ had remarkable influence upon the rate of aggregation. When concentration of (NH₄)₂SO₄ was below 1 M, most of HBsAg aggregated only into OP in 1 h. While with concentration of (NH₄)₂SO₄ above 1 M, most of particles formed PP within 1 h. The aggregation process to PP was irreversible. After removing (NH₄)₂SO₄, the large aggregates could not recover to normal particles and the remaining antigenicity was below 30%.     

Total phenolic compounds and antioxidant potential of Hedychium spicatum Buch. Ham. ex D. Don in west Himalaya,India

Total phenolic compounds and antioxidant potential of Hedychium spicatum were analyzed for 16 different natural populations located in Uttarakhand (west Himalaya) for promotion as health or medicinal food. Total phenolic compounds varied among populations from 4.70 mg gallic acid equivalent (GAE) to 2.84 mg GAE/g dry weight. Three in vitro antioxidant assays, i.e. azinobisethylbenzothiazoline-6-sulphonic acid radical scavenging (ABTS) assay, diphenyl-2-picrylhydrazyl (DPPH) assay and ferric reducing antioxidant power (FRAP) assay, showed significant (p < 0.05) differences across populations. ABTS assay showed highest values of antioxidant potential ranging from 2.581 mM ascorbic acid equivalent (AAE) per 100 g to 1.91 mM AAE per 100 g dry weight, followed by FRAP assay (1.921–0.6635 mM AAE per 100 g). Lowest values were observed for DPPH assay, which varied from 0.549 to 1.059 mM AAE per 100 g dry weight. All assays (ABTS, DPPH and FRAP) showed significant (p < 0.05) correlation with total phenolic compounds. Total phenolic compounds showed a significant relationship (p < 0.05) to altitude.     

Modified cerium(IV)-based antioxidant capacity (CERAC) assay with selectivity over citric acid and simple sugars

A Ce(IV)-based reducing capacity (CERAC) assay was developed to measure the total antioxidant capacity (TAC) of foods, in which Ce(IV) would selectively oxidize antioxidant compounds but not citric acid and reducing sugars. The redox potential of the Ce(IV) oxidant was fine-tuned in 0.3 M H₂SO₄ + 0.7 M Na₂SO₄ aqueous medium for selective oxidation. In the classical Ce(IV)-based assay for which the name CERAC was proposed, the presence of citric acid (at 1.5 × 10^?5 M) caused approximately 25% reduction in Ce(IV) (at 2.0 × 10^?4 M) recovery, whereas in the present method, the presence of citric acid (at 1.0 × 10^?4 M) caused negligible error in the TAC measurement of quercetin. The trolox equivalent antioxidant capacity (TEAC) values in the order of quercetin > rutin > gallic acid > catechin > caffeic acid ≥ ferulic acid > naringenin ≥ naringin > trolox ≥ ascorbic acid were established with the proposed method and were found to be compatible with those found with other antioxidant assays. It is noteworthy that naringin and rutin were also hydrolyzed in the acidic medium of the method so as to exert their full antioxidant capacity not measured by other TAC assays. The proposed TAC assay with Ce(IV) is simple, low-cost, rapid, and can be easily applied in modestly equipped conventional laboratories.     

Poly-(lactic-co-glycolic-acid)-based particulate vaccines: Particle uptake by dendritic cells is a key parameter for immune activation

Poly(lactic-co-glycolic acid) (PLGA) particles have been extensively studied as biodegradable delivery system to improve the potency and safety of protein-based vaccines. In this study we analyzed how the size of PLGA particles, and hence their ability to be engulfed by dendritic cells (DC), affects the type and magnitude of the immune response in comparison to sustained release from a local depot. PLGA microparticles (MP, volume mean diameter ≈ 112 μm) and nanoparticles (NP, Z-average diameter ≈ 350 nm) co-encapsulating ovalbumin (OVA) and poly(I:C), with comparable antigen (Ag) release characteristics, were prepared and characterized. The immunogenicity of these two distinct particulate vaccines was evaluated in vitro and in vivo. NP were efficiently taken up by DC and greatly facilitated MHC I Ag presentation in vitro, whereas DC cultured in the presence of MP failed to internalize significant amounts of Ag and hardly showed MHC I Ag presentation. Vaccination of mice with NP resulted in significantly better priming of Ag-specific CD8⁺ T cells compared to MP and OVA emulsified with incomplete Freund's adjuvant (IFA). Moreover, NP induced a balanced T_H1/T_H2-type antibody response, compared to vaccinations with IFA which stimulated a predominant T_H2-type response, whereas MP failed to increase antibody titers. In conclusion, we postulate that particle internalization is of crucial importance and therefore particulate vaccines should be formulated in the nano- but not micro-size range to achieve efficient uptake, significant MHC class I cross-presentation and effective T and B cell responses.     

Vitamin D levels in fish and shellfish determined by liquid chromatography with ultraviolet detection and mass spectrometry

Vitamin D₃ (cholecalciferol) levels were determined in finfish and shellfish using UV detection at 265 nm (combined with auxiliary full scan UV detection) and selected ion monitoring (SIM) mass spectrometry (MS), using vitamin D₂ (ergocalciferol) as an internal standard. Analysis of standard reference material (SRM) NIST 1849 (Infant/Adult Nutritional Formula) was included to validate the method. Three-point calibration curves were employed, allowing values to be determined over a range of species, from those having little or no detectable vitamin D₃ (e.g., pollock, shrimp) to those with high levels (e.g., salmon with up to 33.23 μg/100 g). The limit of detection (LOD) and limit of quantitation (LOQ) calculated from the uncertainty and intercept of the calibration curves were 1.22 μg/100 g and 5.30 μg/100 g, respectively, based on all analyses (n = 27 sequences). Use of response factors (RF) allowed quantitation at lower levels of vitamin D₃, with an LOQ of <0.20 μg/100 g. The values obtained using the validated methodology agreed well with literature and tabulated database results for most species. However, much lower average vitamin D₃ concentrations were found for oysters (0.05 μg/100 g, raw) and clams (0.18 μg/100 g, cooked) compared to other reports for these products.     

Antioxidant properties of extracts from a white mutant of the mushroom Hypsizigus marmoreus

A white mutant of Hypsizigus marmoreus (Peck) Bigelow (Tricholomataceae) is a new edible mushroom currently available in Taiwan. The ethanolic and hot water extracts were prepared from fruit bodies and mycelia and their antioxidant properties studied. In addition to EC₅₀ values in scavenging abilities on hydroxyl radicals, almost EC₅₀ values were less than 10 mg/mL indicating that these extracts were effective in antioxidant properties assayed. The major antioxidant components found in hot water extracts were total phenols (10.01–13.14 mg/g) and those in ethanolic extracts were total tocopherols (33.33–10.92 mg/g). Correlations of contents of total antioxidant components and total tocopherols (plus β-carotene) with EC₅₀ values of antioxidant activity, reducing power, scavenging ability on 1,1-diphenyl-2-picrylhydrazyl radicals and chelating ability on ferrous ions were established (r=0.445–0.940), whereas the correlation of total phenol content was established only with that of scavenging ability on hydroxyl radicals (r=0.882).