Simultaneous determination of tocopherols,retinol, ester derivatives and β-carotene in milk- and soy-juice based beverages by HPLC with diode-array detection

A simple, sensitive and accurate HPLC method has been developed and validated for the simultaneous determination of α-tocopherol, γ-tocopherol, δ-tocopherol, α-tocopheryl acetate, retinyl palmitate, retinol and β-carotene in milk- and soy-juice based beverages. The assay was performed using a Luna RP-C18 column with methanol: THF: water (67:27:6, v/v/v) as mobile phase, at a flow rate of 0.8 mL/min. Diode-array detector was set at 290 nm for tocopherols, 325 nm for retinols and 440 nm for β-carotene. The method developed and validated is simple and shows good linearity, precision, accuracy and sensitivity and was applied to the analysis of different commercial mixed beverages. The profile of these compounds was different in milk- or soy-juice. Tocopheryl acetate and retinyl palmitate are added in all milk-juice and free γ- and δ-tocopherols are characteristic of soy-juice samples. β-carotene is present in both types of mixed beverages.     

Use and abuse of ascorbic acid—A review

The antiscorbutic¹ and ‘extra-antiscorbutic’ functions of ascorbic acid are reviewed. Although megatherapy remains unproven there is substantial evidence that ascorbic acid may affect metabolism in other ways, e.g. by enhancing heavy metal absorption from the alimentary canal. There is little generally accepted evidence that megadoses of ascorbic acid are of themselves toxic.     

Synthesis of MoO3−x nanosheets and its application in ascorbic acid detection of fruit and vegetables

A new method combining ultraviolet (UV) spectrophotometry and MoO_3−x nanosheets was developed for the rapid and accurate determination of ascorbic acid (AA) content in fruit and vegetables in this study. MoO_3−x nanosheets were prepared by the liquid exfoliation method using AA as the reducing agent, and the content of AA can be determined by a UV spectrophotometer. Experimental conditions for the MoO_3−x nanosheet method, including grinding time, ethanol concentration, sonication time, and water bath temperature were also optimized. The morphology of MoO_3−x nanosheets was characterized by atomic force microscope. The results showed that the average thickness of MoO_3−x nanosheets was 2.1–5.8 nm. The MoO_3−x nanosheets method had a good linearity in the AA concentration range of 0.01–0.05 mg/ml (R² = 0.9996). The limit of detection was 0.031 µg/ml, and the limit of quantitation was 0.095 µg/ml. The spiked recoveries were in the range of 88.79%–116.76%. The MoO_3−x nanosheets method was validated for the determination of AA content in five different fruit and vegetables samples with relative standard deviations less than 2%.     

Simultaneous detection of sulfamethazine,streptomycin, and tylosin in milk by microplate-array based SMM–FIA

This paper presents an approach to simultaneously detect sulfamethazine, streptomycin, and tylosin in milk by indirect competitive multianalyte Fluorescence immunoassay (FIA). Microscope glass slides modified with agarose were used for the preparation of small molecule microarrays (SMMs). Bovine serum albumin (BSA) conjugates of the haptens were immobilized on glass slides. The system consists of four glass slides containing 96 wells formed by an enclosing hydrophobic mask, which precisely matches a standard microplate. All liquid handling and sample processing were fully automated as 96-wells ELISA format. Monoclonal antibodies against sulfamethazine, streptomycin, and tylosin allowed the simultaneous detection of the respective analytes. Antibody binding was detected by a second antibody labeled with Cy5 generating fluorescence, which was scanned with chip scanner. The detection limits for three analytes were 3.26 ng/ml (sulfamethazine), 2.01 ng/ml (streptomycin), and 6.37 ng/ml (tylosin), being far below the respective MRLs. The system proved to be the first SMM–FIA platform having the potential to test for numerous antibiotics in parallel, such being of considerable interest for the control of safety in the food industry.     

Simultaneous determination of aspartame,acesulfame-K,saccharin, citric acid and sodium benzoate in various food products using HPLC–CAD–UV/DAD

A newly developed method for simultaneous determination of aspartame, acesulfame-K, saccharin, citric acid and sodium benzoate in various diet supplements and non-alcoholic beverages in a single run is presented. The analytes were analysed by high-performance liquid chromatography coupled to a charged aerosol (Corona CAD) and ultraviolet–diode array detectors simultaneously connected in series. Mass spectrometer MicrOTOF-QII from Bruker Daltonik (Bremen, Germany) was used to obtain the mass spectra for peak identifications. The method was validated using a Thermo Hypersil Gold-C18 column packed with 5 μm shell particles (150 × 4.6 mm) and methanol–water with 0.05 % TFA gradient mobile phase at a flow rate of 0.80 mL/min. The elaborated method was validated for linearity, precision and accuracy. The analytical results obtained in the validation study were highly satisfying; the recoveries for the analytes studied ranged between 98.1 and 101 % and the precision values from 0.11 to 1.73 %. By these procedures, the three sweeteners (aspartame, acesulfame-K and saccharin), citric acid and sodium benzoate could be well separated and quantitatively determined in varied food products. Hundred millilitres of soft drinks contained on average 5.50 mg of aspartame, 6.38 mg of saccharin, 8.94 mg of acesulfame-K, 9.05 mg of sodium benzoate and 111 mg of citric acid. Citric acid was the most abundant additive in all the samples analysed except for table sweeteners, and its highest concentration was determined in diet supplements, i.e. 347 mg/g. The percentage of adequate daily intake realisation in case of all additives is lower than 10 %, except for sodium benzoate in isotonic drinks (10.1 %).     

Simultaneous determination of deltamethrin,permethrin and malathion in stored wheat samples using continuous sample drop flow microextraction followed by HPLC–UV

Wheat (Triticum aestivum) is an important staple food worldwide used for the manufacture of flour-derived foodstuffs such as bread and noodles. The purpose of this study was to investigate common pesticides in stored wheat at Kermanshah province’s silos in Iran. Continuous sample drop flow microextraction coupled with high-performance liquid chromatography–ultraviolet (HPLC–UV) detection was applied for this purpose. In this technique, a few microliter of organic solvent is transferred to the bottom of a conical test tube and the aqueous solution transforms in form fine droplets while passing through the organic solvent. After extraction, 20 μL of organic solvent containing target analytes was injected into the HPLC–UV. The extraction conditions (including type and volume of extraction solvent, sample solution flow rate, sample solution volume, pH and salt addition) were varied to achieve optimized performance. Under the optimum conditions, the calibration graphs are linear in the range of 0.5–1000 µg kg^?1 and limit of detections (LODs) are in the range of 0.2–0.5 µg kg^?1. Repeatability (intra-day) and reproducibility (inter-day) of method based on seven replicate measurements of 100 µg kg^?1 of target pesticides were in the range of 3.2–5.1% and 4.7–7.2%, respectively. Three out of 36 wheat grain samples contained permethrin exceeding safety levels, but the levels of the other two pesticides in all samples were below the maximum residue levels based on Europe standard level.     

Simultaneous determination of flavanones,hydroxycinnamic acids and alkaloids in citrus fruits by HPLC-DAD–ESI/MS

A simple and accurate method has been developed to simultaneously separate and determine 10 bioactive compounds in citrus fruits by high-performance liquid chromatography coupled with diode array detection and electrospray ionisation mass spectrometry (HPLC-DAD–ESI/MS). This HPLC assay was performed on a reversed-phase C18 column with acetonitrile and 0.1% (v/v) aqueous formic acid as mobile phase. DAD has been performed at 273, 283 and 324 nm for quantification of the alkaloids, flavanones and hydroxycinnamic acids. MS was also employed to identify the each analyte. Ten analytes (naringin, hesperidin, neohesperidin, ferulic acid, p-coumaric acid, chlorogenic acid, caffeic acid, octopamine, synephrine and tyramine) demonstrated good linearity (r ? 0.9990) in a relatively wide concentration range. The method revealed high average recovery (range, 92.1–97.9%) and good precision with interday and intraday variations with less than 4.71%. The limits of detection (LODs) ranged from 0.02 to 0.11 μg/ml, while the limits of quantification (LOQs) were defined in the range of 0.08–0.39 μg/ml. The proposed method has been successfully applied to analyse three types of bioactive constituents in eight citrus hybrids pulps and eight citrus hybrids peels, which has been successfully cultivated in China.     

Comparison of microbiological and HPLC – fluorescence detection methods for determination of niacin in fortified food products

A comparison has been made between results obtained by a recently published HPLC method, involving post-column reaction and fluorescence detection, with a microbiological assay using Lactobacillus plantarum. The HPLC method includes a modified acid hydrolysis extraction step (0.1 M HCl) and yields niacin values from fortified foods somewhat lower than by the microbiological assay. The most significant differences were observed for the cereal-based products. These differences arise principally from the lack of specificity of L. plantarum and from the stronger acid hydrolysis extraction conditions (1 M HCl) of the microbiological assay, which probably releases a part of the non-bioavailable niacin. Moreover by HPLC, excellent recoveries of added nicotinic acid and nicotinamide (95–100%) were obtained and better precision (RSDr=0.3–0.8%) was observed than from the micobiological assay.     

Effect of ascorbic acid and protein concentration on the molecular weight profile of bovine serum albumin and β-lactoglobulin by γ-irradiation

The effects of ascorbic acid and protein concentration on the molecular weight size distribution of BSA and β-lactoglobulin were examined after irradiation of proteins at various doses. Gamma-irradiation of protein solutions caused disruption of the ordered structure of protein molecules resulting in degradation, cross-linking, and aggregation of the polypeptide chains. SDS–PAGE and gel permeation chromatography study showed that ascorbic acid protected the aggregation and degradation of proteins by scavenging oxygen radicals produced by irradiation and the effect of irradiation on protein conformation was more significant at lower concentrations of proteins.     

Quantitative determination of kokumi compounds, γ-glutamyl peptides,in Korean traditional fermented foods,ganjang and doenjang,by LC-MS/MS

Food Science and Biotechnology - Recent studies have shown that γ-glutamyl peptides (GGPs) are recognized by the calcium-sensing receptor and induce kokumi taste. The contents of GGP have been...     

Additive anti-inflammation by a combination of conjugated linoleic acid and α-lipoic acid through molecular interaction between both compounds

Food Science and Biotechnology - Alpha lipoic acid (LA) and conjugated linoleic acid (CLA) have been well-documented on a variety of functional effects in health foods. The main purpose of this...     

Simultaneous determination of bisphenol A,octylphenol, and nonylphenol by pressurised liquid extraction and liquid chromatography–tandem mass spectrometry in powdered milk and infant formulas

A new analytical method, using pressurised liquid extraction (PLE) and liquid chromatography–tandem mass spectrometry (LC–MS/MS), was developed for the simultaneous determination of bisphenol A (BPA), octylphenol (OP) and nonylphenol (NP) in powdered infant formulas (IF) and powdered skimmed milk (PM). The analytes were extracted by PLE, using this optimised conditions: ethyl acetate as solvent, 70 °C of temperature, reversed-phase silica C₁₈ as dispersing agent and three cycles of extraction. The extracts were then injected in LC–MS/MS using a Gemini C₁₈ column and a mixture of 5% water and 95% methanol/acetonitrile, both with 0.1% ammonia, as a mobile phase. Recoveries at different fortification levels (0.5 and 0.05 mg kg⁻¹), were between 89% and 92% for BPA, 84 and 98% for OP, and 93% and 101% for NP. The method was applied to the analysis of samples of PM and IF, bought in Italian and Spanish markets. In positive samples, phenols concentration ranged from 0.07 to 1.29 mg kg⁻¹ for BPA, from 0.028 to 1.55 mg kg⁻¹ for OP and from 0.026 to 1.47 mg kg⁻¹ for NP.     

Antioxidant capacities of α-tocopherol,trolox, ascorbic acid,and ascorbyl palmitate in riboflavin photosensitized oil-in-water emulsions

Antioxidant capacities of α-tocopherol, trolox, ascorbic acid, and ascorbyl palmitate at 0.01, 0.1, and 1.0 mM in riboflavin photosensitized oil-in-water (O/W) emulsions were determined using headspace oxygen depletion, lipid hydroperoxide, and headspace volatile analyses. After 32 h visible light irradiation, headspace oxygen in O/W emulsions without adding antioxidants, with 1.0 mM α-tocopherol, trolox, ascorbic acid, and ascorbyl palmitate decreased to 18.50%, 18.85%, 16.01%, 17.92%, and 19.88%, respectively, whereas those samples in the dark were 20.74%. Trolox and ascorbic acid acted as prooxidants while their lipophilic counterparts, α-tocopherol and ascorbyl palmitate, respectively showed antioxidant properties. Similar antioxidative or prooxidative properties of the tested compounds can be observed in the results of lipid hydroperoxides and headspace volatiles. However, the prooxidant and antioxidant properties of the tested compounds were not clearly shown at 0.01 and 0.1 mM concentration. Both the type and concentration of antioxidants influenced the antioxidant capacities in riboflavin photosensitized O/W emulsions.     

Simultaneous quantitative determination,identification and qualitative screening of pesticides in fruits and vegetables using LC-Q-Orbitrap™-MS

A method based on QuEChERS extraction and LC-quadrupole-Orbitrap? MS detection was established utilising an improved fully non-targeted way of data acquisition with and without fragmentation. A full-scan acquisition event without fragmentation (resolving power 70 000) was followed by five consecutive fragmentation events (variable data independent acquisition – vDIA; resolving power 35 000) where all ions from the full-scan range are fragmented. Compared with fragmentation in a single event (all-ion fragmentation – AIF), this improves both selectivity and sensitivity for the fragment ions, which is beneficial for screening performance and identification capability. The method was validated, using the data from the same measurements, for two types of analysis: quantitation/identification and qualitative screening. The quantitative validation, performed according to the guidelines in SANCO/12571/2013, tested the performance of the method for 184 compounds in lettuce and orange at two spiking levels: 10 and 50 ng g^?1. The validation showed that the vast majority of the compounds met the criteria for trueness and precision set in the SANCO guidance document. In the qualitative validation the same 184 compounds were used to test the untargeted screening capabilities of the method. In this validation the compounds were spiked at three levels into 11 different fruit and vegetable matrices, which were measured twice on separate days. Taking all data from the qualitative validation together, an overall detection rate of 92% was achieved at the 10 ng g^?1 level, increasing to 98% at 200 ng g^?1. A screening detection limit (as defined in the SANCO guidelines) of 10 ng g^?1 could be achieved for 134 compounds. For 39 and two pesticides the SDL was 50 and 200 ng g^?1, respectively. For the other nine compounds no SDL could be established. The identification (ion ratio) criteria as recommended in the SANCO document could be met for 93% of the detected pesticide/matrix/concentration combinations. The outcome of both validations shows that the described method can be used to combine quantitative analysis and the identification of frequently detected pesticides (so far typically done using triple quadrupole MS/MS) with a qualitative screening to be used for a wide range of less frequent detected compounds in one measurement.     

The anti-inflammatory effect of lycopene complements the antioxidant action of ascorbic acid and α-tocopherol

Tomato foods contain bioactive compounds, such as lycopene, ascorbic acid and α-tocopherol, which are assumed to show synergistic effects. The aim of the study was to investigate this presumed synergy. The effect on lipid peroxidation and inflammation was assessed. Lipid peroxidation was effectively inhibited by combinations of the compounds compared to the single compounds. Synergy between the combination of ascorbic acid and α-tocopherol was confirmed. Lycopene on its own effectively reduced inflammation by inhibiting the release of TNF-α and stimulating IL-10 production. The combination of lycopene, ascorbic acid and α-tocopherol tended to display a synergistic interaction on IL-10 production. Our observations highlight that lycopene mitigates inflammation, whereas ascorbic acid and α-tocopherol efficiently protect against lipid peroxidation. Both activities are complementary since they diminish the process of inflammation differently on different levels. In relation to health, this is an added value of fruit and vegetables such as tomato products that contain complementary bio-active compounds.     

Effect of phosphate, ascorbic acid and α-tocopherol injected at one-location with tumbling on quality of roast beef

The purpose of this study was to evaluate if continuous non-vacuum or vacuum tumbling improves the quality of roast beef utilizing the one location injection. Basically, fresh roast beef treated by one location injection with tumbling had significantly different quality compared to non-tumbled ones. However, the cooked roast beef did not significantly exhibit better quality due to tumbling. There was insignificant difference of TBARS value for whole meat among treatments at day 0. The control had significantly higher TBARS value compared to roast beef with non-vacuum and vacuum tumbled samples at day 2. At 4, 7 and 14 days of refrigerated storage, the control maintained the significantly highest values when compared to the other treatments that had similar TBARS values. The addition of three antioxidants was the major contributor to lipid stability of the cooked roast beef.     

Sensitive determination of domoic acid in shellfish by on-line coupling of weak anion exchange solid-phase extraction and liquid chromatography–diode array detection–tandem mass spectrometry

An automated method based on the use of on-line solid-phase extraction (SPE) coupled to liquid chromatography with diode array detection and tandem mass spectrometry (LC–DAD–MS/MS) has been developed for the determination of domoic acid in shellfish. The on-line coupling of SPE and liquid chromatography was accomplished by a column switching approach. A weak anion exchange (WAX) sorbent was selected for the SPE procedure, allowing a selective cleanup of shellfish extracts. High sensitivity was achieved by on-line pre-concentration of large volume injections (50–1000 μL). A simple protein precipitation cleanup with acetone was used to efficiently remove proteins from shellfish extracts, preventing possible column clogging during chromatographic separation.     

Simultaneous analysis of Nε-(carboxymethyl)lysine,reducing sugars,and lysine during the dairy thermal process

A new analytical method allowing the simultaneous quantification of Nε-(carboxymethyl)lysine (CML), lysine, and reducing sugars (glucose, lactose, and galactose) is described. It is based on high performance anion-exchange chromatography with pulsed amperometric electrochemical detection. This method demonstrated a low limit of quantification (0.385 to 0.866 mg/L), excellent linear correlation (R² > 0.997), and desired calibration range (3.125 to 25 mg/L). In addition, lactose-lysine solutions containing sulfite (4 to 400 mmol/L) were heated at 110°C for 2 h. The results showed that sulfite inhibited the formation of CML and promoted the consumption of reducing sugars and lysine in the Maillard reaction model. The method proved to be useful for simultaneous analysis of CML, lysine, and reducing sugars (glucose, galactose, and lactose) in the Maillard reaction system. Moreover, sulfite was an effective inhibitor of CML formation.     

Impact of high pressure processing on total antioxidant activity,phenolic, ascorbic acid,anthocyanin content and colour of strawberry and blackberry purées

The present study was undertaken to assess the effect of high pressure treatments and conventional thermal processing on antioxidant activity, levels of key antioxidant groups (polyphenols, ascorbic acid and anthocyanins) and the colour of strawberry and blackberry purées. Bioactive compounds (cyanidin-3-glycoside, pelargonidin-3-glucoside, ascorbic acid) and antioxidant activity were measured in strawberry and blackberry purées subjected to high pressure treatment (400, 500, 600 MPa/15 min/10–30 °C) and thermal treatments (70 °C/2 min). Samples were assessed immediately after processing. Different pressure treatments did not cause any significant change in ascorbic acid (p > 0.05). In contrast, following thermal processing (P₇₀ ≥ 2 min) ascorbic acid degradation was 21% (p < 0.05) as compared to unprocessed purée. However, no significant changes in anthocyanins were observed between pressure treated and unprocessed purées (p > 0.05), whereas conventional thermal treatments significantly reduced the levels (p < 0.05). In general, antioxidant activities of pressure treated strawberry and blackberry purées were significantly higher (p < 0.05) than in thermally processed samples. Colour changes were minor (ΔE) for pressurised purées but the differences were slightly higher for thermally treated samples. Redness of purées was well retained in high pressure treated samples. Therefore processing strawberry and blackberry by high pressure processing could be an efficient method to preserve these products quality. Hence high pressure processing (HPP) at moderate temperatures may be appropriate to produce nutritious and fresh like purées.Industrial relevanceThis research paper provides scientific evidence of the potential benefits of high pressure processing in comparison to thermal treatments in retaining important bioactive compounds. Antioxidant activity (ARP), ascorbic acid, and anthocyanins after exposure to high pressure treatments (400–600 MPa) were well retained. Our results also show that redness and colour intensity of strawberry and blackberry purées were better preserved by high pressure processing than conventional thermal treatment. From a nutritional perspective, high pressure processing is an attractive food preservation technology and offers opportunities for horticultural and food processing industries to meet the growing demand from consumers for healthier food products. Therefore high pressure processed foods could be sold at a premium than their thermally processed counterparts as they will have retained their fresh-like properties.