Antioxidant Activity and Determination of Phenolic Compounds from <Emphasis Type="Italic">Eugenia involucrata</Emphasis> DC. Fruits by UHPLC-MS/MS

Fruits have been the focus of several studies aimed at finding new antioxidant sources for protection against the damage caused by reactive species. In this study, the antioxidant activity and the presence of phenolic compounds in all parts (peel, pulp, and seeds) of Eugenia involucrata DC. fruits were evaluated. DPPH^·, ABTS^·+, and ORAC methods were used to determine the antioxidant activity, and an UHPLC-MS/MS method was developed for determining the phenolic compounds (gallic, chlorogenic, ferulic, p-coumaric and ellagic acids, quercetin, and myricetin). In the determination of both antioxidant activity and phenolic composition, the efficiency of solvents with different polarities—methanol/H₂O (80:20, v/v), ethanol/H₂O (80:20, v/v), methanol/acidified water with phosphoric acid pH 3.00 (80:20, v/v), and ethyl acetate—for the extraction of the phenolic compounds, was also evaluated. All parts of E. involucrata fruits showed antioxidant activity, in the range of 36.68 ± 1.44 to 873.87 ± 18.24 μmol TE g^?1, being the highest values found in the seeds and peel when more polar extraction solvents were used. Six, five, and three phenolic compounds were identified and quantified in the pulp, peel, and seeds, respectively, with the highest abundance as p-coumaric acid (14 ± 2 mg kg^?1) in the pulp, quercetin (47 ± 5 mg kg^?1) in the peel, and gallic acid (74 ± 4 mg kg^?1) in the seeds, also when more polar solvents were used. Although antioxidant activity methods suggested that the peel and seeds have more antioxidant potential, a wider variety of compounds were determined in the pulp.     

Design of Sonotrode Ultrasound-Assisted Extraction of Phenolic Compounds from <Emphasis Type="Italic">Psidium guajava</Emphasis> L. Leaves

Psidium guajava L. has gained a special attention as health plant due to the presence of phenolic compounds. Box-Behnken design (BBD) has been applied for the extraction of target compounds from guava leaves via sonotrode ultrasound-assisted extraction (UAE). Different extraction times (5, 30, and 55 min), ratios of ethanol/water (50, 75, and 100% (v/v)), and ultrasound (US) power (80, 240, and 400 W) were tested to find their effect on the sum of phenolic compound (SPC), flavonols and flavan-3-ols via HPLC-ESI-QqQ-MS, and antioxidant activity (DPPH and TEAC assays). The best process conditions were as follows: 40 min, 60% ethanol/water (v/v), and 200 W. Established method has been used to extract phenolic compounds in two guava leaves varieties (pyrifera and pomifera). Pyrifera var. showed greater values of the SPC via HPLC-ESI-QqQ-MS (49.7 mg/g leaf dry weight (d.w.)), flavonols (12.51 mg/g d.w.), flavan-3-ols (7.20 mg/g d.w.), individual phenolic compounds, and antioxidant activity (8970 ± 5 and 465 ± 6 μmol Trolox/g leaf d.w, respectively) than pomifera var. Conventional extraction showed lower amounts of phenolic compounds (7.81 ± 0.03 and 4.64 ± 0.01 mg/g leaf d.w. for flavonols and flavan-3ols, respectively) in comparison to the ultrasound-assisted ones.     

High-Performance Liquid Chromatography with Fluorescence Detection for Simultaneous Analysis of Retinoids (Retinyl Palmitate,Retinyl Acetate,and Free Retinol) and α-, β-, γ-, and δ-Tocopherols in Foods

A method based on high-performance liquid chromatography with fluorescence detection for the simultaneous analysis of retinoids (vitamin A) and tocopherols (vitamin E) was developed. This method consists of an isocratic solution using hexane/ethyl acetate (85:15, v/v) as the mobile phase and fluorescence detection using a time program that sets the excitation (Ex) and emission (Em) wavelengths at adequate elution times for retinoids (Ex 342 nm, Em 476 nm) and tocopherols (Ex 298 nm, Em 325 nm), respectively. The separation of three retinoids (retinyl palmitate, retinyl acetate, and free retinol) and four tocopherol homologs was achieved with sufficient reproducibility and quantitative ability. Additionally, the necessity of saponification was considered. As a result, saponification was not used in this method because of the complexity of the procedure and the loss of free retinol. The retinoid and tocopherol contents of various foods were evaluated using the developed method. Our method could evaluate the retinoid and tocopherol contents of fish (eel, Anguilla japonica, and amberjack, Seriola dumerili) muscle and liver, roasted soybean (Glycine max) flour, and Japanese torreya seed (Torreya nucifera). Additionally, our method could be applied to the determination of retinoids and tocopherols not only in foods but also in supplements and cosmetics.     

Preparation and Release Behavior of Gelatin-Based Capsules of Antioxidants from Ethanolic Extracts of Thai Riceberry Bran

This study aimed to devise an environment-friendly and effective, yet simple and practicable, antioxidant extraction and encapsulation method from Riceberry bran, whose extract was used thereafter for developing highly efficient antioxidant capsules. Ethanolic Riceberry bran extracts with high total phenolic content, total flavonoid content, total anthocyanin content, and antioxidant activity (using DPPH radical scavenging activity and ferric reducing antioxidant power assay) were obtained using ultrasonic-assisted extraction. The optimum conditions for producing the capsules, such as types of gelatin, concentrations of gelatin, and the Riceberry bran extract concentrations, were studied. Capsules produced by incorporating 1% (w/v) of acid-treated gelatin (type A) and 1% (w/v) of Riceberry bran extract yielded higher chemical properties. When dispersed in water at 37 °C, the capsules exhibited a high release of antioxidants. Moreover, the capsule showed a lower degradation rate of antioxidants under simulated gastrointestinal conditions compared to the crude extract.     

Determination of Baclofen Residue in Muscle,Liver, Kidney and Fat of Swine by Liquid Chromatography-Tandem Mass Spectrometry

Baclofen was illegally used in veterinary clinical medicine as a growth-promoting agent. To date, few methods have been developed for the monitoring of baclofen in animal tissues. In this study, a sensitive and efficient liquid chromatography-tandem mass spectrometry (LC-MS/MS) method to identify and quantify baclofen in the muscle, liver, kidney, and fat of swine was developed and validated. Baclofen was extracted from tissues with ammonium acetate buffer (pH 5.2) and isolated with isopropyl-ethyl acetate (4:6, v/v). Then, a solid phase extraction using MCX cartridge was used to clean up the extracts. The elution was evaporated to dryness and reconstituted with water/methanol (90:10 v/v). All samples were determined by LC-MS/MS system through positive ionization in a multiple reaction monitoring (MRM) mode. The proposed method was validated by evaluation of specificity, linearity, recovery, accuracy, precision, LOD, and LOQ values according to Commission Decision 2002/657/EC. Estimated limit of quantification for baclofen in the muscle, liver, kidney, and fat of this method was 1.00 μg/kg, respectively. The mean intra- and inter-day assay accuracies fell within a range 88.5–93.9% and 86.2–93.2%, respectively. The mean intra- and inter-day precisions were 1.78 and 4.95% (RSD < 15%), respectively. The proposed method has proved to be suitable for accurate quantitative determination of baclofen for residue analysis.     

Effect of Tannin Extracts on Biofilms and Attachment of <Emphasis Type="Italic">Escherichia coli</Emphasis> on Lettuce Leaves

Lettuce is often involved in foodborne outbreaks caused by pathogenic Escherichia coli. Current control strategies have often proved ineffective to ensure safe food production. For that reason, the present study compared the efficacy of tannin extracts and chlorine treatments on the reduction of E. coli ATCC 25922 adhered to lettuce leaves. E. coli was inoculated artificially on leaf surfaces of fresh crisp lettuce. Effectiveness of water, chlorine (200 mg/L), and three commercial available tannin extracts from Acacia mearnsii De Wild. (tannin AQ (2 %, w/v), tannin SG (1 %, v/v) and tannin SM (1 %, v/v)) treatments was evaluated using the viable plate count method and scanning electron microscopy (SEM). SEM results revealed that bacterial cells are attached as individual cells and in clusters to the leaf surface after 2 h of incubation. Biofilm formation was observed after 24 h of incubation. The tannin SM treatment was able to reduce counts in approximately 2 log CFU/cm² on leaf segments. However, treatment was less effective in the reduction of E. coli counts after 24 h of incubation when compared to 2 h incubation of the same extract. The results suggest that the tannin SM extract diminishes E. coli counts adhered to and under biofilm formation on lettuce leaves and its effect is similar to the use of chlorine solutions.     

Dispersive Liquid–Liquid Microextraction Combined With Micellar Electrokinetic Chromatography for the Determination of Some Photoinitiators in Fruit Juice

A fast and simple technique composed of dispersive liquid–liquid microextraction (DLLME) and micellar electrokinetic chromatography (MEKC) with diode array detector (DAD) was developed for the determination of multi-photoinitiators in fruit juice. Seven photoinitiators were separated in MEKC using a 25 mM borate buffer of pH 8.0, containing 24 mM sodium dodecyl sulfate (SDS), 10 mM β-cyclodextrin (β-CD), and 12.5 % acetonitrile (v/v). A CD-modified MEKC made this method more suitable for the determination of isopropylthioxanthone (ITX) isomers including 2-IXT and 4-ITX than the recently prescribed methods. A DLLME procedure was used as an offline preconcentration strategy. The satisfactory recoveries obtained by DLLME spiked at two spiked levels ranged from 85.6 to 124.7 % with relative standard deviations (RSDs) below 14 %. The limits of quantification (LOQs) ranged from 2.1 to 6.0 μg kg^?1.     

Characterization of Biodegradable Films Based on <Emphasis Type="Italic">Salvia hispanica</Emphasis> L. Protein and Mucilage

Biodegradable films of chia by-products (mucilage and protein-rich fraction (PF)) incorporated with clove essential oil (CEO) were obtained and characterized. The effects of polymer concentration (PC; 1.0–3.0 %, w/v) and CEO concentration (0.1–1.0 %, v/v) were evaluated as well as the pH (7–10), using a 2³ factorial design with four central points. The films exhibited moisture values between 11.6 and 52.1 % (d.b.), which decreased (p?<?0.05) with increasing PC and CEO. The thickness of the films increased (p?<?0.05) with increasing PC. PC and pH influenced (p?<?0.05) the lightness (L) and variation in color between red and green (a). The orientation of the color to yellow-blue hues (b) decreased significantly (p?<?0.05) with increasing PC. Transparency was significantly lower and higher (p?<?0.05) than PC and CEO, respectively. The film surface morphology was evaluated using atomic force miscrocope images, and thermogravimetric analysis (TGA) was performed to study the thermal stability of the films. The displacement and tensile strength were significantly lower (p?<?0.05) at higher concentrations of CEO, this variable being the only one with a significant effect. The chemical composition of the films was confirmed utilizing Fourier transform infrared (FTIR) spectroscopy. The proportion of CEO added to the films had a significant influence on antimicrobial activity, inhibiting the growth of both Escherichia coli and Staphylococcus aureus.     

Establishment and Application of Infant Formula Fingerprints by RP-HPLC

An efficient method for rapid and simple identification of infant formula quality was investigated so as to prevent brand counterfeit of infant formulas. Reversed-phase, high-performance liquid chromatography (RP-HPLC) method combined with chemometric method was developed for fingerprints analysis. To optimize the RP-HPLC conditions, the RP-HPLC analysis was performed on a C₈ column by using gradient elution with 0.1% (v/v) aqueous trifluoroacetic acid (TFA) in water as mobile phase A and 0.1% (v/v) TFA in acetonitrile as mobile phase B, the flow rate was 0.5 mL min^?1, and the detection wavelength was set at 214 nm. Three different stages of infant formulas of two series (R₁ and R₂) of R brand were analyzed to establish infant formula fingerprints of each series at different stages under optimal conditions. Five major common peaks in each chromatogram of the infant formulas were used in fingerprint analysis. The results showed that the RP-HPLC fingerprints and principal component analysis (PCA) method can effectively differentiate the infant formula of different brands, as well as the different series of infant formulas of the same brand, which provide an effective testing method for authenticity identification and brand protection in infant formulas.     

Chlorophyll Fluorescence Imaging for Monitoring the Effects of Minimal Processing and Warm Water Treatments on Physiological Properties and Quality Attributes of Fresh-Cut Salads

In this study, chlorophyll fluorescence imaging (CFI) was used to monitor plant stress induced by cutting of mini romaine lettuce (Lactuca sativa L. var. longifolia) and by cutting and washing of endive (Cichorium endivia L.) during storage. Regarding the more detailed study of endive fresh-cut salads, we additionally monitored respiratory activity, phenylalanine ammonia lyase (PAL) activity, contents of plant pigments, and cut edge browning. Determination of maximum quantum efficiency F _v/F _m was feasible through sealed consumer-sized film bags, thus, enabling the non-invasive monitoring of both fresh-cut salad types in the corresponding modified atmosphere during storage. Cutting of romaine lettuce provoked a partially reversible drop of F _v/F _m during the first 24 h. Subsequently, F _v/F _m of cut romaine strongly decreased with elapsing shelf life, whereas intact leaves exhibited only a slight decline. Regarding minimally processed endive, warm water washing progressively reduced F _v/F _m with increasing heat exposure, while respiratory activities and the content of accessory pigments remained unaffected. The heat-dependent decrease of F _v/F _m was correlated to the inhibition of the PAL activity. Mildly warm washing (40 °C, 120 s; 45 °C, 60 s) reduced PAL activities, while F_v/F_m remained widely unaffected and visual quality was only partially improved. However, warm water washing at elevated temperatures (45 °C, 120 s; 50 °C, 30–60 s) enabled maximum visual quality retention, accompanied by a significant decrease of F _v/F _m. CFI may represent a useful tool to monitor the stress conditions due to cutting and warm water treatments, hence, allowing the systematic improvement of fresh-cut produce.     

Determination of Total Sugar Content in Soy-Based Drinks Using Infrared Spectroscopy and Chemometrics

Partial least square (PLS) regression models were developed and compared in order to determine the total sugar content in soy-based drinks using an infrared spectroscopy technique known as attenuated total reflectance Fourier transform infrared (ATR-FTIR). On a spectrophotometer set for analyzing on the middle infrared region, spectral band of 1900 to 900 cm^?1, commercial samples of soy beverage were analyzed, as well as samples with crescent water additions of 5, 10, and 20% v/v. Reference data for total sugars were obtained using the Lane-Eynon method. To construct regression models, algorithms of interval partial least square (iPLS) and synergy of interval partial least square (siPLS) were applied using iToolbox package on Matlab 8.1 environment. Kennard-Stone algorithm was used to the selection of calibration and prediction sets. Two models have been the best obtained: the first was an iPLS with seven latent variables, which selected the spectral band of 1399–900 cm^?1 and presented root mean square error of cross-validation (RMSECV)?=?0.1678% (w/w). The second best model was siPLS with six latent variables, which selected spectral bands of 1025–1150 and 1151–1476 cm^?1 and presented RMSECV?=?0.1963% (w/w). The proposed method presents advantages such as a small-required amount of sample for spectrum achievement, no sample destruction, and a high analytical frequency.     

A TLC-HPLC Method for Determination of Thiamphenicol in Pig,Chicken, and Fish Feedstuffs

An effective thin-layer chromatography (TLC) purification procedure coupled to high-performance liquid chromatography (HPLC) method was developed for the determination of thiamphenicol (TAP) in pig, chicken, and fish feedstuffs. The feedstuff samples were extracted with ethyl acetate, defatted with n-hexane saturated with acetonitrile, and further purified by TLC. The chromatographic separation was performed on a Waters Symmetry C₁₈ column using an isocratic procedure with acetonitrile-water (21.7:78.3, v/v) at 0.6 mL/min. The ultraviolet (UV) detector was set at a wavelength of 225 nm. The TAP concentrations in feedstuff samples were quantified using a standard curve. Good linear correlations (y?=?162,630x???2381.7, r?>?0.9998) were achieved within the concentration range of 0.05–10.00 μg/mL. The recoveries of TAP spiked at levels of 1, 10, and 100 μg/g ranged from 82.0 to 114.9% with the intra-day and inter-day relative standard deviation (RSD) less than 9.0%. The limit of detection (LOD) and limit of quantitation (LOQ) were 0.02 and 0.03 mg/kg for pig feedstuffs, 0.02 and 0.04 mg/kg for chicken feedstuffs, and 0.02 and 0.03 mg/kg for fish feedstuffs, respectively. This reliable, simple, and cost-effective method could be applied to the routine monitoring of TAP in animal feedstuffs.     

Integrated Analytical Methods to Characterize Lipids from <Emphasis Type="Italic">Prosopis</Emphasis> spp. and <Emphasis Type="Italic">Ceratonia siliqua</Emphasis> Seed Germ Flour

Flour from seed germ of European carob (Ceratonia siliqua) and South American algarrobo (Prosopis spp.) is a potential ingredient for health-promoting baked products. Herein, lipids from germ of three Argentinean Prosopis (P. alba, P. nigra, and P. ruscifolia) and one European carob species were characterized in detail, exploiting an array of up-to-date analytical techniques. Total lipids ranged from 7.1 to 8.1% (w/w). Linoleic acid (C18:2, ω-6) predominated the GC flame ionization detector profiles of fatty acid in all samples (43.3–50.6%). Prosopis spp. contained 6–7% of C20–C24 fatty acids and, consistently, C56–C60 triacylglycerols, as detected by MALDI-TOF mass spectrometry (MS), which were practically missing in C. siliqua germ. Phospholipids were isolated by hydroxyapatite chromatography, characterized by MALDI-TOF MS and grossly quantified by attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy. Because of a relatively high content (9.5–11.8%, v/v), phospholipids might increase the antioxidant potential and improve the baking performances of flour fortified with carob and algarrobo seed germ.     

Green Approach for Sample Preparation and Determination of Anthocyanins from <Emphasis Type="Italic">Lycium ruthenicum</Emphasis> Murr. Using a <Emphasis Type="Italic">β-</Emphasis>Cyclodextrin-Based Extraction Method Coupled with UPLC-DAD Analysis

This study aimed to develop and optimize a β-cyclodextrin (β-CD)-based technique for extracting anthocyanins from Lycium ruthenicum Murr. and to establish a ultra-high-performance liquid chromatography-diode array detector (UPLC-DAD) method for their analysis. β-CD solutions produced higher extraction yields of petunidin-3-O-(trans-p-coumaroyl)-rutinoside-5-O-glucoside and total anthocyanins from L. ruthenicum fruit than did pure water and aqueous hydroxypropyl-β-cyclodextrin (HPβ-CD) and ethanol and methanol solutions. Extraction at 50 °C for 30 min using 1.65% β-CD solution and a liquid/solid ratio of 15:1 produced the optimal extraction yield of L. ruthenicum anthocyanins. A UPLC-DAD method was developed for the determination of L. ruthenicum anthocyanins using an ethanol-based mobile phase, and the primary anthocyanins were identified using two-dimensional LC-MS/MS. Method validation showed that the developed method was accurate, stable, and reliable for the analysis of petunidin-3-O-(trans-p-coumaroyl)-rutinoside-5-O-glucoside and total anthocyanins from L. ruthenicum fruit. The present study showed that β-CD-based extraction coupled with UPLC-DAD analysis is an efficient and green method for the extraction and analysis of anthocyanins from L. ruthenicum fruit.     

Uncertainty of Trypsin Inhibitor Activity Measurement of Legume Crops Using Microtiter Plate Method

Trypsin inhibitors could limit utilization of legumes in human nutrition, but they could also have beneficial health effects. The objective of this study was to measure trypsin inhibitor activity (TIA) of different legumes using microtiter plate method and to identify factors that contribute to uncertainty of TIA measurement. TIA measurements were performed on seeds of faba bean, pea, common vetch, soybean, and common bean cultivars. The significant effect of legume crop on TIA measurement uncertainty was confirmed with P = 0.045. Certain sources of measurement uncertainty were related with the content of trypsin inhibitors (Tis) in legume seeds. In respect to that, significant effect of level of sample dilution (P ? 0.001) was confirmed. Significant influence of the repeated absorbance measurement of sample reaction mixture on uncertainty of TIA measurement was identified (P ? 0.001), and it took 60% of overall TIA measurement uncertainty for soybean cultivars. TIA of soybean cultivars exceeded 90 TUI/mg. Repeated absorbance measurement of positive control reaction mixture took 70% of TIA measurement uncertainty of cultivars with TIA lesser than 4.5 TUI/mg. Graduated cylinder used for preparation of the final sample solutions took the range from 45 to 90% of overall TIA measurement uncertainty of the cultivars whose TIA were in the middle of previously mentioned. The uncertainty of TIA measurement of legume crops was not studied before; thus, this study pointed out that acquiring insight into factors contributing to uncertainty of TIA measurement could give directions for improvement of TIA testing if microtiter plate method is used.     

Determination of Seven <Emphasis Type="Italic">N</Emphasis>-nitrosamines in Agricultural Food Matrices Using GC-PCI-MS/MS

The quantitative analytical methods for seven N-nitrosamines including N-nitrosodimethylamine (NDMA), N-nitrosomethylethylamine (NMEA), N-nitrosodiethylamine (NDEA), N-nitrosodibutylamine (NDBA), N-nitrosopiperidine (NPIP), N-nitrosopyrrolidine (NPYR), and N-nitrosomorpholine (NMOR) were established for agricultural food matrices. Four food matrices were used for the method development: rice soup as a fatless solid matrix, apple juice as a fatless liquid matrix, corn oil as a fat-rich liquid matrix, and 20 % alcohol as an alcohol matrix. A combination of solid-supported liquid-liquid extraction (SLLE) using Extrelut NT and a solid phase extraction (SPE) using Florisil was employed for fatless matrices. For an alcohol matrix, only SLLE was used without SPE, and liquid-liquid extraction (LLE) was established for a fat-rich matrix. The extract was analyzed by gas chromatography-positive chemical ionization-tandem mass spectrometry (GC-PCI-MS/MS) using ammonia gas as an ion source. Linearity, recovery, repeatability, inter-day precision, reproducibility, and uncertainty were evaluated for method validation using four matrices. Method detection limits for all of the investigated N-nitrosamines were ranged from 0.10 to 0.18 μg/kg for the rice soup, from 0.10 to 0.19 μg/kg for the apple juice, 0.10 μg/kg for the corn oil, and from 0.10 to 0.25 μg/kg for 20 % alcohol, depending on N-nitrosamines. Established methods were applied to determine seven N-nitrosamines in some agricultural food products.     

Effect of Dipping Pre-treatment with Unripe Grape Juice on Dried “Golden Delicious” Apple Slices

The consumption of apple chips is increasing in the last decades because of the consumer’s preferences towards healthy snacks. However, the enzymatic browning, which is attributed mainly to polyphenol oxidase (PPO, EC 1.10.3.1) activity, negatively affects the sensory, nutritional, and antioxidant properties of dried apples as a consequence of the oxidation of phenolic substrates during post-harvest stages. The antibrowning and antioxidant effects of dipping pre-treatments with unripe grape juice as well as reference formulations including a mixture of 1% w/v ascorbic acid and 1% w/v citric acid, 6% w/v NatureSeal®, and 0.1% w/v sodium metabisulfite were evaluated by spectrophotometric and colorimetric assays on dried “Golden Delicious” apple slices. Based on HPLC analysis, the treated apple slices were enriched with bioactive compounds which effectively improved antioxidant capacity and limited enzymatic browning by increasing lightness, reducing color change, and inhibiting PPO activity. Hence, the juice of unripe grapes recovered as agricultural wastes during bunch thinning of vineyards could be proposed as a safe, inexpensive, and eco-friendly alternative to conventional antibrowning treatments in apple processing.     

Development and characterization of reconstituted hydrogel from <Emphasis Type="Italic">Aloe vera</Emphasis> (<Emphasis Type="Italic">Aloe barbadensis</Emphasis> Miller) powder

Structural and rheological characterization of reconstituted hydrogels developed from A. vera non-fibrous alcohol insoluble residue (NFAIR) powder using different methods [viz., shaking (S), heating-shaking (HS), and heating (H)] and concentrations (viz., 0.2–1.6 %, w/v) was carried out. Functional group distribution by FTIR spectroscopy and Congo red (CR) method revealed the presence of acetylated acemannan in A. vera powder. Dynamic oscillation studies of A. vera (NFAIR) fluids at all concentrations of 0.2–1.6 %, w/v, showed gel strength in the order of H > HS > S method. However, in H method, increase in concentration from 0.2 to 1.6 %, w/v showed the conformational transition from semi-diluted solution to weak gel nature. Rheological models described the effect of heating temperatures (HT); 30–90 °C, and times (Ht); 15–60 min on viscoelastic behavior in reconstituted A. vera fluids. The reconstituted A. vera hydrogel prepared with a concentration of 1.6 %, w/v using 50 °C (HT) and 30 min (Ht) condition showed a good agreement with the Power law (storage modulus, G′) and Weak gel model (complex modulus, G*) fitted data (R² > 0.94) resulting higher viscoelastic moduli intercepts; G′₀ (71.5 Pa s ^n′), G″₀ (33.5 Pa s ^n″), lower slopes; n′ (0.22), n″ (0.06), higher network strength (A _F , 121.3 Pa s^1/z ) and number of network (z, 5.3) values. The obtained results suggested that heating at 50 °C/30 min can develop aqueous weak gel networks of A. vera with enhanced gel strength which may be utilized as a novel gelling agent for wide variety of targeted applications in food and pharmaceutical sectors.     

Screening of Phenolic Antioxidants in Edible Oils by HPTLC-DPPH Assay and MS Confirmation

The cytotoxicity of phenolic antioxidants had attracted marked attention, posing serious challenges to food safety. This paper presented a screening method for two major phenolic antioxidants (butylated hydroxytoluene and tert-butylhydroquinone) added in edible oils. To specifically visualize the targeted compounds after developing with toluene/ethyl acetate/methanol 8:1:1 (v/v/v) to 70 mm solvent front, the plate was subjected to a standardized 1,1-diphenyl-2-picrylhydrazyl assay. In addition to synoptical eye inspection, accurate quantification was realized by modified densitometric measurements: fluorescence mode, excitation wavelength 530 nm (D₂ and W lamp) without optical filter, which offered satisfactory sensitivity (8.5–17.5 mg/kg) and acceptable linearity (R²?>?0.999 within 50–200 ng/zone). Moreover, the established method was validated with edible oil samples, against EU Directive 2006/52/EC. Apart from that, the unambiguous confirmation of positive results was conveniently achieved by TLC-MS interface-mediated mass spectrometry. Featuring the merits of screening conception, the proposed method not only reached the goal of accurate quantification and conclusive identification of multi-phenolic antioxidants, but also excellently balanced the simplicity, detectability, and throughput of the screening workup. Therefore, it might be an attractive alternative to conventional methods.     

Optimization of Extraction Parameters of Total Phenolics from <Emphasis Type="Italic">Annona crassiflora</Emphasis> Mart. (Araticum) Fruits Using Response Surface Methodology

In this study, response surface methodology was used to optimize the extraction temperature (25–75 °C) and ethanol concentration (0–70 %, ethanol/water, v/v) to maximize the extraction of total phenolic compounds (TPC) from araticum pulp. The efficiency of the extraction process was monitored over time, and equilibrium conditions were reached between 60–90 min. A second-order polynomial model was adequately fit to the experimental data with an adjusted R ² of 0.9793 (p < 0.0001) showing that the model could efficiently predict the TPC content. Optimum extraction conditions were ethanol concentration of 46 % (v/v), extraction temperature of 75 °C and extraction time of 90 min. Under the optimum conditions, the araticum pulp showed high TPC content (4.67 g GAE/100 g dw) and also high antioxidant activity in the different assays used (46.56 μg/mL, 683.65 μmol TE/g and 1593.72 μmol TE/g for DPPH IC₅₀, TEAC and T-ORAC_FL, respectively). From our extraction procedure, we successfully recovered a significantly higher amount of TPC compared to other studies in the literature to date (1.5–22-fold higher). Furthermore, TPC and antioxidant activity were present in the fruit in levels that are difficult to find in other common fruits. These results expose a potential approach for improving human health through consumption of araticum fruit.