Characterization and Quantification of Zinc Oxide and Titanium Dioxide Nanoparticles in Foods

There has been growing concern in recent years about contamination of foods by engineered nanoparticles (NPs) due to their increasing applications in food packaging materials, pesticides, and other products. In this study, we report a systematic approach to detect, characterize, and quantify engineered NPs (i.e., zinc oxide (ZnO) and titanium dioxide (TiO₂) NPs) in food products. A series of concentrations of ZnO and TiO₂ NPs from 0.05 to 1 wt% were spiked into corn starch, yam starch, and wheat flour. The presence of engineered NPs in foods was detected and measured by scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy and transmission electron microscopy. The average sizes of ZnO and TiO₂ NPs were around 38 and 40 nm in diameter, respectively. Most ZnO NPs were in either spherical or rod-like shape, while most TiO₂ NPs were in a spherical shape. The concentrations of engineered NPs in food samples were measured by inductively coupled plasma optical emission spectrometry. Calibration curves were plotted for quantification of NPs in foods (R ²?=?0.984 and 0.995 for ZnO NPs in corn starch and wheat flour, respectively; R ²?=?0.992 and 0.998 for TiO₂ NPs in yam starch and wheat flour, respectively). The results of this study could help develop systematic methodologies for detection, characterization, and quantification of NPs in food matrices.     

Simultaneous Detection of Salmonella,Listeria monocytogenes,and Staphylococcus aureus by Multiplex Real-Time PCR Assays Using High-Resolution Melting

A method combining multiplex real-time polymerase chain reaction (PCR) with high-resolution melting (HRM) analysis for rapid and specific simultaneous detection of Salmonella, Listeria monocytogenes, and Staphylococcus aureus was developed. The method included a melting-curve analysis of products and was evaluated by specificity, sensitivity and reproducibility analyses. Sensitivity and reproducibility analyses was both conducted by genomic DNA extracted from serial dilutions for each target pathogen. Assays with artificially inoculated and naturally contaminated samples after enrichment were also conducted. In the specificity test, there was no nonspecific amplification of the 44 nontarget pathogens, whereas the actual T _m values were 79.38?±?0.14, 82.54?±?0.15, and 77.36?±?0.14 °C for Salmonella, L. monocytogenes, and S. aureus, respectively. The sensitivity of the method was 3.5?×?10² CFU ml^?1 for Salmonella and L. monocytogenes and 3.5?×?10³ CFU ml^?1 for S. aureus. The coefficients of variation of T _m values ranged 0.51–1.03 % for Salmonella, 1.63–2.11 % for L. monocytogenes, and 0.75–2.17 % for S. aureus in intraassay, and ranged 0.81–2.43 % for Salmonella, 1.97–2.35 % for L. monocytogenes, and 0.93–3.93 % for S. aureus in interassay. The detection limit in artificially inoculated samples (n?=?50) was 5 CFU (25 g)^?1 food for the three tested pathogens. In the naturally contaminated samples (n?=?120),Salmonella DNA was detected by HRM, sequencing, and conventional culture-based methods at a positive rate of 25.00, 25.00, and 24.17 %, respectively; the corresponding rates for L. monocytogenes were 14.17, 14.17, and 14.17 %, respectively, while those for S. aureus were 16.7, 16.7, and 16.7 %, respectively.     

Identification and Quantification of Dityrosine in Grain Proteins by Isotope Dilution Liquid Chromatography-Tandem Mass Spectrometry

A novel liquid chromatography-tandem mass spectrometry method was developed and validated for identification and quantification of dityrosine in zein protein. The zein samples spiked with a dityrosine standard and 3,3-¹³C₆-dityrosine, as the internal standard were hydrolysed in a mixture of 6 N hydrochloric acid and propionic acid followed by cleaning-up using Sep Pak C₁₈ cartridges. Good linear regression (R ² = 0.999) was obtained in the range 1–1000 ng/mL. Method limit of detection and method limit of quantification were 42.1 and 140 ng/g, respectively. Recoveries were from 92 to 95.2%. Precision and inter-day reproducibility expressed as relative standard deviation were from 3.9 to 22.1% and from 4.4 to 16.6%, respectively. The validated method was applied to quantify dityrosine in various grain proteins. The levels of dityrosine ranged from 0.38 to 1.92 ng/mg. This validated method will be of great value for understanding the role of dityrosine in grain food texture.     

The Release of Carotenoids from a Light-Protected Antioxidant Active Packaging Designed to Improve the Stability of Soybean Oil

An antioxidant active packaging was developed by coextruding two layers of high-density polyethylene (HDPE). Bags were made with the film in which the inner layer, designed to be in contact with food, contained marigold flower (Tagetes erecta) extract rich in carotenoids. The outer layer of the film was added with titanium dioxide (TiO₂) to decrease the effect of commercial lighting on the degradation of carotenoids. Four bilayer films were produced: added with TiO₂ and carotenoids, added with carotenoids, added with TiO₂, and with no additives at all (control film). Degradation of color and astaxanthin in the films was delayed by the addition of the TiO₂ when they were stored under commercial lighting at 25 °C. Bags made of these films produced an improvement on the soybean oil stability at 25 °C as a result of a synergic effect of light protection by TiO₂ and carotenoids release. This release was measured as diffusion coefficients of carotenoids from the films toward soybean oil at 10, 25, and 40 °C (2.10–19.26?×?10^?11 cm² s^?1) with activation energy of 53.66 kJ mol^?1. In conclusion, the combination of the two layers of HDPE added with TiO₂ and carotenoids introduced opacity and permitted to extend the active effect of the films in contact with soybean oil. Moreover, the effect of temperature on the diffusion of carotenoids showed that this new active packaging is able to exert its function in conditions of transport, storage, and commercialization of food.     

Simultaneous Determination of Aflatoxin B1 and Aflatoxin M1 in Food Matrices by Enzyme-Linked Immunosorbent Assay

Aflatoxins are a class of highly toxic chemical contaminants occurring in food. Consumption of aflatoxin-contaminated food can lead to harmful effects on human health. A rapid and reliable analysis of aflatoxins in food is crucial. In this study, we generated a broad–specific monoclonal antibody (MAb) 3 C10 against aflatoxin B₁ (AFB₁). The MAb 3 C10 binds specifically to AFB₁ and AFM₁ and has a IC₅₀ of 0.13 μg L^?1 for AFB₁ and 0.16 μg L^?1 for AFM₁. Furthermore, the MAb showed high cross-reactivity to AFB₂, AFG₁, and AFG₂. To enable simultaneous AFB₁ and AFM₁ detection in different food matrices, an indirect competitive enzyme-linked immunosorbent assay (icELISA) based on MAb 3 C10 has been developed and optimized. In addition, the extraction methods of different food matrices (peanut, corn, soybean, wheat flour, rice, soy sauce, vinegar, wine, raw milk, pure milk, skimmed milk, and yogurt) were established. The average recovery ranged from 73 to 121 %, with relative standard deviation values less than 15 %. The limit of detection was 0.52?+?0.36 μg kg^?1 (mean?+?3SD) for AFB₁ in eight agricultural products and 0.031?+?0.015 μg kg^?1 (mean?+?3SD) for AFM₁ in four dairy products. The sensitivity of icELISA was below the limit set by the European Commission for aflatoxin detection in different food matrices and similar to LC–MS/MS method. We demonstrate a rapid, simple, and reliable method for simultaneous screening of AFB₁ and AFM₁ in different food matrices.     

Determination of benzo[α]pyrene in edible oil using tetraoxocalix[2]arene[2]triazine bonded silica SPE sorbent

Benzo[α]pyrene (BaP) is a well-known carcinogen in edible oil. In this study, a method combined solid-phase extraction (SPE) with fluorescent detection was developed using tetraoxocalix[2]arene[2]triazine sorbent (SiO₂-OCA) for the clean-up and enrichment of BaP. The interaction between SiO₂-OCA and BaP involves a donor–acceptor complex mechanism. The experimental procedure was as follows: BaP was extracted from edible oil with DMF/H₂O (9:1, v/v). Then, the ratio of DMF/H₂O was adjusted to 1:2 prior to SPE. The final concentrate was analysed using a fluorescence detector at excitation and emission wavelengths of 255 and 420 nm. The method was fully validated. The linearity was in the range of 0.1–100 μg kg^?1 with a coefficient of 0.999. The limits of detection and quantification were 0.03 and 0.1 μg kg^?1, respectively. The average recoveries were in the range of 88.0 ? 122.3%. The intraday and interday precisions were 6.8% and 9.2%, respectively. Compared with other methods, the method reported in this article shows a good detection limit, high reproducibility and recovery and linearity over a broad concentration range. This established method was also applied to evaluate real samples. The concentration of six tested samples was below 5 μg kg^?1.     

Analysis and risk assessment of ethyl carbamate in various fermented foods

Ethyl carbamate (EC) was analyzed in fermented foods, comprising various matrices; subsequently, a risk assessment for EC was carried out. In total, 128 fermented foods were purchased from department stores and traditional markets in Korea. The samples comprised 55 lactic acid–fermented vegetable (kimchi), 53 fermented soybean paste (doenjang, gochujang, cheonggukjang, and ssamjang), 20 fermented fish products (jeotgal), 18 yoghurt, 37 bread, 12 cheese, and 23 vinegar samples. The level of EC in fermented soybean pastes ranged from not detectable to 240.2 ng g^?1. EC was not detected in kimchi, jeotgals, yoghurt, and cheese. Bread and vinegar contained EC up to 3.70 and 16.79 ng g^?1, respectively. The estimated daily intake and chronic daily intake of EC were 1.98 ng kg body weight (bw)^?1 day^?1, 1.50 ng kg bw^?1 day^?1, respectively. Excess cancer risk and margin of exposure of EC were 7.5 × 10^?8 and 151,515, respectively.     

ZnO Nanoparticle Ionic Liquids Carbon Paste Electrode as a Voltammetric Sensor for Determination of Sudan I in the Presence of Vitamin B<Subscript>6</Subscript> in Food Samples

Room-temperature ionic liquid n-hexyl-3-methylimidazolium hexafluoro phosphate as a binder and ZnO nanoparticle (ZnO/NPs) as a sensor were used to construct a new ZnO/NPs carbon ionic liquid paste electrode (ZnO/NPs/IL/CPE), which exhibited enhanced electrochemical behavior as compared with the traditional carbon paste electrode with paraffin for electrooxidation of Sudan I. This modified electrode exhibited a potent and persistent electron mediating behavior followed by well separated oxidation peaks of Sudan I and vitamin B₆. The peaks current of square wave voltammograms (SWV) of Sudan I and vitamin B₆ increased linearly with their concentration in the ranges of 0.01–400 μM Sudan I and 0.5–800 μM vitamin B₆. The detection limits for Sudan I and vitamin B₆ were 0.008–0.2 μM, respectively. The modified electrode has been successfully applied for the assay of Sudan I and vitamin B₆ in food samples.     

Production optimization,purification, and characterization of a novel acid protease from a fusant by Aspergillus oryzae and Aspergillus niger

The production of a novel acid protease was enhanced by 44 % through statistical optimization. The cultural parameters, such as inoculum size, temperature, moisture content, and incubation time, were 8.59 × 10⁵ g^?1 dry koji, 31 °C, 57 %, and 86 h, respectively. This novel acid protease was purified by 17 folds with a recovery yield of 33.56 % and a specific activity of 4,105.49 U mg^?1. Far-UV circular dichroic spectra revealed that this purified protease contained 7.1 % α-helix, 64.1 % β-sheet, and 32 % aperiodic coil. This novel acid protease was active over the temperature range of 35–55 °C with optimum temperature of 40 °C and was stable in the pH range of 2.5–6.5 with optimum pH of 3.5. Mn²⁺ enhanced its activity while Co²⁺ showed inhibitory effect. With casein as substrate, the kinetic parameters of K _m, V _max, energy of activation (E _a), and attenuation index of inactivation velocity by heat inducing (λ) were 0.96 mg mL^?1, 135.14 μmol min^?1 mg^?1, 64.11 kJ mol^?1, and 0.59, respectively.     

Speciation of Inorganic Antimony in Food and Water Samples by Flow Injection On-line Nano γ-Alumina Micro-column Solid-Phase Extraction Coupled with Slotted Tube Atom Trapping Flame Atomic Absorption Spectrometry

Nano γ-alumina, with ultra-high specific surface area (387.2 m²?g^?1), has been synthesized and used as a promising adsorbent material in solid-phase extraction. A simple, sensitive, and economic method was developed for speciation of inorganic antimony by slotted tube atom trapping flame atomic absorption spectrometry (STAT-FAAS) after flow injection on-line nano γ-alumina micro-column solid-phase extraction. In this method, Sb(III)–diethyldithiocarbamate (DDTC) complexes produced on-line from DDTC and Sb(III) were adsorbed by the synthesized γ-alumina nanoparticles in a micro-column, then eluted by 1.0 mol?L^?1 HNO₃ in methanol, whereas Sb(V) remained in aqueous solution. The total inorganic Sb was determined by the same procedure after Sb(V) was reduced with thiourea. Under optimal conditions, the enrichment factor was 56.5 and the detection sensitivity was improved 40-fold for antimony by STAT-FAAS compared to conventional FAAS. The limit of detection was 6.0 ng?L^?1 for Sb(III) and 8.2 ng?L^?1 for Sb(V), respectively. The intra-day precision (RSDs, n?=?11) were 2.8 % for Sb(III) and 3.5 % for Sb(V), respectively, and the inter-day precision (n?=?3) were 7.1 % for Sb(III) and 8.4 % for Sb(V), respectively. The recoveries for the spiked samples were 93–107 %. The proposed method was applied to speciation of inorganic antimony in water and food samples successfully.     

Effects of maltodextrin glycosylation following limited enzymatic hydrolysis on the functional and conformational properties of soybean protein isolate

The soy protein hydrolysate (HSPI) was first prepared using Neutrase and then glycosylated with maltodextrin (Md) at different incubation times (120, 180, 240, 270, and 300 min). The effect of glycosylation following limited enzymatic hydrolysis on the physicochemical properties of HSPI was investigated. The sodium dodecylsulphate polyacrylamide gel electrophoresis was used to confirm the covalent conjugation and determine the changes in the molecular weight of soybean protein isolate (SPI) during the structural modification. Surface hydrophobicity (H ₀) measurements revealed that limited hydrolysis as well as glycosylation at 120 min increased H ₀; however, further glycosylation decreased H ₀ due to the shielding effect of the maltodextrin bound. The increased secondary, tertiary conformation stability was confirmed by the far-UV circular dichroism spectroscopy, the intrinsic fluorescence analysis, and the results of differential scanning calorimetry. Subsequently, the functional properties including solubility, heat stability, emulsifying property, as well as antioxidant activities were evaluated. Results indicated that the emulsifying activity index was improved notably from 86.13 ± 1.31 m²/g for the native SPI to 109.07 ± 4.45 m²/g for HSPI–Md conjugates after 270-min incubation. Additionally, the glycosylation had obviously positive effects on the antioxidant activities of the modified SPI proteins. Therefore, HSPI–Md conjugates might be used as potential emulsifiers or multifunctional wall materials for the microencapsulation of bioactive ingredients.     

Hybrid Amine-Functionalized Titania/Silica Nanoparticles for Solid-Phase Extraction of Lead,Copper, and Zinc from Food and Water Samples: Kinetics and Equilibrium Studies

In the present study, hybrid amine-functionalized titania/silica nanoparticles were employed as a new and novel adsorbent for solid-phase extraction of Pb²⁺, Cu²⁺, and Zn²⁺ ions prior to their determination using flame atomic absorption spectrometry. Under the best conditions (including adsorbent, 0.4 g; eluent, 5.0 mL nitric acid (HNO₃), 3.0 mol L^?1, 1.0 mL min^?1; and sample, pH 5.0, 3.0 mL min^?1), detection limits, adsorption capacities, and preconcentration factors were 0.12–0.24 μg L^?1, 7.1–20.7 mg g^?1, and 200, respectively. To predict the adsorption isotherms, different isotherm models were studied and the obtained results showed that the Langmuir model is the most suitable one to explain the experimental data. The kinetics of the reaction followed pseudo-second-order kinetic model. Thermodynamic parameters like free energy (ΔG ⁰) and enthalpy (ΔH ⁰) confirmed the spontaneous and exothermic nature of the process. The method was successfully applied for determination of the analytes in different food and water samples.     

An alkaline protease from Kocuria kristinae F7: properties and characterization of its hydrolysates from soy protein

An alkaline serine protease (SF1) from Kocuria kristinae F7 was purified. The molecular mass of the SF1 protease was estimated to be 57 kDa by sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS–PAGE). The N-terminal amino acid sequence of the first 14 amino acids of the SF1 protease showed low homology with bacterial proteases, suggesting that the enzyme had not been described previously. The SF1 protease exhibited maximal activity at pH 9.0 and 60 °C. The activity of the SF1 protease was enhanced by the presence of Ca²⁺ and Mg²⁺ ions. It showed high stability in the presence of NaCl and ethanol. Reverse-phase high-performance liquid chromatography (RP-HPLC) analyses indicated that soybean protein isolates treated with the SF1 protease generated four principal new hydrophilic peptides. Mass spectrometry analyses indicate that the distribution of molecular weight of these peptides was from 0.705 to 1.305 kDa. Hydrolysis of soybean protein isolates with the SF1 protease increased the level of total free amino acids, essential amino acids and flavor amino acids. The SF1 protease may decrease the bitterness of soy protein hydrolysates. The results showed that the SF1 protease of Kocuria kristinae F7 appears to be good candidate enzyme for potential application in acceleration of fermented soybean food ripening.     

Development of CO<Subscript>2</Subscript>-Mediated Switchable Hydrophilicity Solvent-Based Microextraction Combined with HPLC-UV for the Determination of Bisphenols in Foods and Drinks

In traditional dispersive liquid-liquid microextraction procedures, both extraction and dispersive solvents are required, and thus, it increases the consumption of organic solvent. Herein, we reported a CO₂-mediated switchable hydrophilicity solvent-based microextraction (SHS-BME) for the determination of bisphenol compounds (BPCs) in complex milk and drink samples. N,N-Dimethylcyclohexylamine was used as a switchable hydrophilicity solvent; it can switch reversibly between one form that is miscible with water and another that forms a biphasic mixture with water, and thus allow extraction of the analytes in a homogeneous phase without dispersive solvent. Several important parameters were screened and optimized by single factor experiments and central composite design as follows: 782 μL of switchable solvent, 375 μL of NaOH solvent, and 1.1:1 switchable solvent/water (v/v). Under the optimized SHS-BME conditions, the limit of detections (LODs) for BPCs in milk, orange juice, and energy drink samples were in the range of 0.27–0.40 μg L^?1 for BPE, 0.17–0.30 μg L^?1 for BPA, and 0.50–0.67 μg L^?1 for BPB, respectively, and the extraction recoveries for BPCs were in the range of 79.5–103.4% in milk, of 84.5–97.5% in orange juice, and of 91.9–101.2% in energy drinks. The precision of the method, based on relative standard deviations (RSDs), ranged from 1.7 to 4.8% and from 2.1 to 5.7% for intra-day and inter-day comparisons, respectively. In total, this SHS-BME method possesses many advantages, such as high extraction recovery and high detection sensitivity (low LODs and RSDs), no requirement of dispersive solvent, simple operational procedure, reducing the pretreatment time and workload, and so on. Therefore, it has a great potential application value for detection of trace BPCs in routine food tests.     

Voltammetric Determination of Thymol in Oregano Using CeO<Subscript>2</Subscript>-Modified Electrode in Brij® 35 Micellar Medium

Glassy carbon electrode (GCE) modified with CeO₂ nanoparticles dispersed in 0.01 M Brij® 35 (CeO₂-Brij® 35/GCE) has been developed for the determination of thymol in micellar medium. Scanning electron microscopy (SEM) data confirm immobilization of the nanomaterial on the electrode surface. The electrooxidation of thymol on CeO₂-Brij® 35/GCE is an irreversible diffusion-controlled process with participation of two electrons and two protons. Differential pulse voltammetry has been used for the quantification of thymol. The linear dynamic range of the thymol determination is 0.700–10.1 and 10.1–606 μM with the limits of detection and quantification 0.20 and 0.65 μM, respectively. The approach developed has been applied for the quantification of thymol in oregano spices using preliminary micellar extraction with Brij® 35. The results of voltammetric determination are in good agreement with the data of standard spectrophotometric method.     

Rapid assessment of the quality of deep frying oils used by street vendors with Fourier transform infrared spectroscopy

Deterioration of deep frying oils used by street vendors is one of the major food safety concerns. Fourier transform infrared (FTIR) spectroscopy coupled with partial least squares (PLS) regression was applied for rapid evaluation of the quality of deep frying oils collected from different street vendors (n = 109) using various frying processes in Shanghai. The levels of free fatty acids (FFA), total polar compounds (TPC), and viscosity of oils were determined with conventional methods and used as reference values for developing PLS models. The FFA (0.07–1.78 mg (KOH)/g) of all tested frying oils were below the maximum allowed value, while 5.5 % of oils had TPC (3.19–54.47 %) above the maximum allowed value (27 %) based upon the related chinese standards. FTIR coupled with PLS regression resulted in less satisfying results for FFA determination (predictability for soybean oils: R² = 0.709, SEP = 0.14, RPD = 1.83), but showed great promise for rapid determination of viscosity (model predictability: R² = 0.921–0.945, SEP = 0.68–0.71, RPD = 3.54–3.98) and TPC (predictability for soybean oils: R² = 0.790–0.931, SEP = 1.89–2.94, RPD = 2.16–3.55) of frying oils from different commercial settings. Developing separated PLS models for shortening and non-shortening oils improved predictability, particularly for the analysis of TPC.     

Biocomposite Films Based on κ-Carrageenan/Locust Bean Gum Blends and Clays: Physical and Antimicrobial Properties

The aims of this work were to evaluate the physical and antimicrobial properties of biodegradable films composed of mixtures of κ-carrageenan (κ-car) and locust bean gum (LBG) when organically modified clay Cloisite 30B (C30B) was dispersed in the biopolymer matrix. Film-forming solutions were prepared by adding C30B (ranging from 0 to 16 wt.%) into the κ-car/LBG solution (40/60 wt.%) with 0.3 % (w/v) of glycerol. Barrier properties (water vapour permeability, P _vapour; CO₂ and O₂ permeabilities), mechanical properties (tensile strength, TS, and elongation-at-break, EB) and thermal stability of the resulting films were determined and related with the incorporation of C30B. Also, X-ray diffraction (XRD) was done in order to investigate the effect of C30B in film structure. Antimicrobial effects of these films against Listeria monocytogenes, Escherichia coli and Salmonella enterica were also evaluated. The increase of clay concentration causes a decrease of P _vapour (from 5.34?×?10^?11 to 3.19?×?10^?11 g (m s?Pa)^?1) and an increase of the CO₂ permeability (from 2.26?×?10^?14 to 2.91?×?10^?14 g (m s?Pa)^?1) and did not changed significantly the O₂ permeability for films with 0 and 16 wt.% C30B, respectively. Films with 16 wt.% clay exhibited the highest values of TS (33.82 MPa) and EB (29.82 %). XRD patterns of the films indicated that a degree of exfoliation is attained depending on clay concentration. κ-car/LBG–C30B films exhibited an inhibitory effect only against L. monocytogenes. κ-car/LBG–C30B composite films are a promising alternative to synthetic films in order to improve the shelf life and safety of food products.     

Water Adsorption and Glass Transition of Spray-Dried Soy Sauce Powders Using Maltodextrins as Carrier

Moisture adsorption isotherm and glass transition temperature of various spray-dried soy sauce powders containing different types and concentrations of maltodextrins were studied and compared. Maltodextrins of dextrose equivalent (DE)?=?5, DE?=?10 and DE?=?15, respectively, with concentrations of 20 or 40 % (w/v) were used as carrier agents. The equilibrium moisture content was reduced with increased maltodextrin concentration, whereas it was not apparently influenced by the value of maltodextrin DE. Both the Brunauer–Emmett–Teller (BET) and Guggenheim–Anderson–de Boer (GAB) models could be applied to simulate the moisture adsorption behaviour of the soy sauce powders. The monolayer moisture content of the powders was determined by fitting experimental data to the BET/GAB models with a _w up to 0.53, although both models could fit satisfactorily with the experimental data to a higher water activity level_. The glass transition temperatures (T _g) of the powders equilibrated under various water activities were determined using a differential scanning calorimeter. Increasing moisture adsorption of the soy sauce powders resulted in a T _g reduction, and the experimental T _g values fitted the Gordon–Taylor model well. The BET and Gordon–Taylor models were applied together to predict the critical moisture contents (i.e. 0.0464–0.0777 g water/g dry matter) and water activities (i.e. 0.032–0.241), above which the soy sauce powders become vulnerable to degradation and changes in their physicochemical properties.     

Vacuum-Belt Drying of Rabbiteye Blueberry (Vaccinium ashei) Slurries: Influence of Drying Conditions on Physical and Quality Properties of Blueberry Powder

Continuous vacuum-belt drying was studied as a means to produce high-quality powders from blueberry slurries, with limited degradation of anthocyanins. Drying was performed at three different temperatures (80, 95, 110 °C) and the resulting dried material (a _w?～?0.2) ground into powders. Drying times ranged from 70 min at 80 °C to 50 min at 110 °C. Maltodextrin (MD) was used as a drying agent at three levels (0.3, 0.45, and 0.6 kg/kg dry blueberry solid). Powders were purple, with no signs of browning, and similar in appearance to those produced by freeze-drying. Increasing MD level and drying temperature decreased the hygroscopicity of the powders. Moisture isotherms showed type 3 behavior and were well-fit with the Guggenheim–Anderson–de Boer equation. Higher levels of MD improved flowability of the powders, with >93 % of the powders with MD flowing from the test fixture after 30 s, compared to only 62.1 % emerging for powders without MD. Powders dried at 80 °C were slightly darker (L*?=?25.73–28.4) than those produced 110 °C (L*?=?27.10–28.53), presumably due to less degradation of anthocyanins. Total monomeric anthocyanins (TMA) for MD dried at 80 °C (13.1 mg C3G/g) were not different than for freeze-dried blueberries. Higher drying temperatures caused some loss of TMA. Higher levels of MD result in lower TMA by increasing the amount of dry matter in the powders. Vacuum-belt drying at 80 °C with 0.3 kg MD/kg dry solids produced non-sticky powders with anthocyanin content similar to freeze-dried powders.     

Updated evaluation of the migration of styrene monomer and oligomers from polystyrene food contact materials to foods and food simulants

Due to the 2011 labelling of styrene monomer as “reasonably anticipated to be a human carcinogen” by the National Institutes of Health’s National Toxicology Program (NTP) and the controversy over whether styrene oligomers mimic the physiological effects of estrogen, an updated review of styrene monomer and oligomers in food and food contact materials (FCMs) was performed. The concentrations of styrene monomer and oligomers were determined in 24 polystyrene (PS) products and ranged from 9.3 to 3100 mg kg^–1 for the styrene monomer, 130–2900 mg kg^–1 for the sum of three styrene dimers, and 220–16,000 mg kg^–1 for the sum of six styrene trimers. Foods in contact with PS packaging had styrene monomer concentrations ranging from 2.6 to 163 ng g^–1; dimer concentrations from the limit of quantitation (LOQ) to 4.8 ng g^–1 and trimer concentrations were all below the LOQ (2 ng g^–1). Diffusion coefficients (D_p) and partition coefficients (K) were also calculated for styrene dimers and trimers. The results presented here indicate that styrene monomer concentrations in foods have not significantly changed since the 1980s and monomer concentrations in food packaging quantified in this study were all below USFDA limits. Although styrene dimers and trimers are present in higher concentrations in PS FCMs than the monomer, their migration to food is limited because of their high K values (4 × 10² to 2 × 10⁶) and their low diffusion coefficients in PS products. Additionally, diffusion coefficients calculated using USFDA-recommended food simulants and Arrhenius plots describing the temperature dependence of styrene dimers and trimers can be used in future calculations of dietary intake of the styrene oligomers.