Microwave-assisted digestion using diluted HNO3 and H2O2 for macro and microelements determination in guarana samples by ICP OES

Production, characterisation, and biological properties of Tenebrio molitor-derived oligopeptides

Three protein hydrolysates from Tenebrio molitor were obtained by enzymatic hydrolysis employing two food-grade proteases (i.e. Alcalase and Flavourzyme), and a complete characterisation of their composition was done. The digestion-derived products were obtained using the INFOGEST protocol. In vitro antioxidant activity and anti-inflammatory activities were evaluated. Tenebrio molitor flour and the protein hydrolysates showed a high ability to scavenge the DPPH radical (EC50 values from 0.30 to 0.87 mg/mL). The hydrolysate obtained with a combination of the two food-grade proteases could decrease the gene expression of pro-inflammatory genes after being digested. Furthermore, the peptidome was fully determined for the first time for T. molitor hydrolysates and digests, and 40 peptides were selected based on their bioactivity to be evaluated by in silico tools, including prediction tools and molecular docking. These results provide new perspectives on the use of edible insects as sustainable and not nutritionally disadvantageous food for human consumption.

Methylxanthine and Flavonoid Contents from Guarana Seeds (Paullinia cupana): Comparison of Different Drying Techniques and Effects of UV Radiation

Guarana seeds are typically processed using one of three drying methods: traditional sun exposure, greenhouse drying, or the alguidar oven technique. In our research, we evaluated the contents of methylxanthines and flavan-3-ols in sun- and alguidar-dried guarana seeds from Bahia State's Low Sul Identity Territory. Caffeine, theobromine, catechin, and epicatechin were determined by high-performance liquid chromatography with UV-visible detection (HPLC/UV-vis). Statistical tools, including analysis of variance (ANOVA), Tukey's test, and exploratory analysis, were employed to analyze the obtained data. Our findings indicated that the flavan-3-ols content in sun-dried guarana samples was lower compared to those dried using the alguidar oven, possibly due to exposure to ultraviolet radiation from solar energy. Conversely, we observed no significant differences (p > 0.05) in the average contents of methylxanthines between the two drying methods. Our supplementary experiments involving UV-A and UV-C radiation lamps revealed a decreasing trend in methylxanthines and flavan-3-ols contents with increasing duration of UV radiation exposure.

Multi-elemental composition of botanical preparations and probabilistic evaluation of toxic metals and metalloids intake upon dietary exposure

The aim of this study was to evaluate the inorganic elemental composition (49 elements) of 29 botanical preparations obtained from fruits, leaves, peels, seeds, roots, fungi, and spirulina by using inductively coupled-mass spectrometry and a mercury analyzer. Simultaneously, the risk associated with the chronic dietary exposure to 12 toxic metals and metalloids among the European population was evaluated by using a probabilistic approach based on Monte Carlo simulations. The analysis revealed worrying intake levels of Al, As, and Ni, primarily stemming from the consumption of spirulina-, peel-, and leaf-based botanicals by younger age groups. The intake of As from all analyzed botanicals posed a significant risk for infants, yielding margins of exposure (MOEs) below 1, while those deriving from peel-based botanicals raised concerns across all age groups (MOEs = 0.04-2.3). The consumption of peel-based botanicals contributed substantially (13-130%) also to the tolerable daily intake of Ni for infants, toddlers, and children, while that of spirulina-based botanicals raised concerns related to Al intake also among adults, contributing to 11-176% of the tolerable weekly intake of this element. The findings achieved underscore the importance of implementing a monitoring framework to address chemical contamination of botanicals, thus ensuring their safety for regular consumers.

Concentration of heavy metals in soil and leaves of Conocarpus Erectus Tree: A Biomonitoring Study, Ahvaz, Iran

Heavy metals biomonitoring was performed using the Conocarpus erectus tree in Ahvaz city. Composite leaf and soil samples were collected from 23 selected stations. The concentrations of heavy metals (Pb, Zn, Cd, Cu, Fe and Mn) in leaf and soil samples, and bioavailability of metals in soil samples were determined. Examination of soil physicochemical parameters proved neutral to slightly alkaline nature, and low organic matter content in the soil samples. The mean concentration of heavy metals in soil was: Fe > Mn > Zn > Pb > Cu. Ecological risk assessment of heavy metals was in the range of safe to low risk (RI < 150). Although the concentration of metals in the more polluted areas was higher in both leaf and soil samples, there was no significant relationship between the concentrations of metals in the leaf and soil samples. This relationship is even lower between the bioavailable component of metals in the soil and the concentration of metals in the leaves. Transfer factor values based on total contents of metals in soil samples indicated that Conocarpus erectus is mostly contaminated with Zn and Cu. The results of Accumulation factor of plant revealed that Pb, Zn, and Fe were mostly enriched in the plant by anthropogenic activities. MAI values in heavy and light traffic, and industrial areas were 11.88, 8.01 and 8.15, respectively. In general, it is evident that the Conocarpus erectus leaves accumulate heavy metals in polluted areas, so it can be used as a bioindicator of air pollution with heavy metals in regions with similar conditions.

Microwave-assisted UV digestion of starch and skimmed milk powder: Environmentally friendly protocol for essential and toxic elements determination

The present work evaluated a microwave-assisted wet digestion method using diluted HNO3 with in situ UV radiation for the digestion of starch and skimmed milk powder for further metals determination by spectrometric plasma-based techniques. The sample digestion was conducted using an in situ UV lamp (electrodeless discharge lamp), and the digestion efficiency was improved by employing O2 (20 bar) and 2 mL 30 % H2O2 as auxiliary reagents. The accuracy of the proposed digestion method was evaluated by metals determination (Ca, Cd, Cu, Fe, K, Mg, Mo, Mn, Na, Pb, and Zn) in certificated reference material, which agreed with certified values (Student t-test <0,05). With the use of a UV lamp an environmentally friendly protocol was developed for starch and skimmed milk powder digestion using 0.1 mol L-1 HNO3 with auxiliary reagents (H2O2 or O2). The RCC value ranged from 0.9 to 1.2 % (starch and skimmed milk powder, respectively). The simultaneous cooling approach further improved the digestion efficiency (RCC <0,3 % for both samples), allowing to use milder digestion conditions, or even just water, being environmentally friendly, reducing the waste generation and reagents consumption, allowing food quality control through a greener approach.

Identification of the Bioavailable Peptidome of Chia Protein Hydrolysate and the In Silico Evaluation of Its Antioxidant and ACE Inhibitory Potential

The incorporation of novel, functional, and sustainable foods in human diets is increasing because of their beneficial effects and environmental-friendly nature. Chia (Salvia hispanica L.) has proved to be a suitable source of bioactive peptides via enzymatic hydrolysis. These peptides could be responsible for modulating several physiological processes if able to reach the target organ. The bioavailable peptides contained in a hydrolysate obtained with Alcalase, as functional foods, were identified using a transwell system with Caco-2 cell culture as the absorption model. Furthermore, 20 unique peptides with a molecular weight lower than 1000 Da and the higher statistical significance of the peptide-precursor spectrum match (-10 log P) were assessed by in silico tools to suggest which peptides could be those exerting the demonstrated bioactivity. From the characterized peptides, considering the molecular features and the results obtained, the peptides AGDAHWTY, VDAHPIKAM, PNYHPNPR, and ALPPGAVHW are anticipated to be contributing to the antioxidant and/or ACE inhibitor activity of the chia protein hydrolysates.

Determination of major and trace elements in plant samples by inductively coupled plasma optical emission spectrometry with deep eutectic solvent extraction based on choline chloride and carboxylic acids

A rapid, precise, and environmentally friendly approach utilizing an ultrasound assisted deep eutectic solvent-based extraction method was developed for the extraction of Ca, Fe, K, Mg, Mn, Na, P, S and Zn from plant samples. The investigation was conducted on deep eutectic solvents that are based on choline chloride and carboxylic acids. The determination of target analytes in the extracts was carried out using inductively coupled plasma-optical emission spectrometry (ICP-OES). The DESs based on malic acid were found to exhibit the highest extraction recovery values (95-106%). The parameters affecting the extraction of target analytes were optimized using standard reference materials. The target analytes can be effectively extracted from plant samples using 0.5 g of DESs and ultrasonication for 40 minutes. The determination results of the reference samples indicated that the relative error (RE) was below 15.1%, and the relative standard deviation (RSD) was less than 6.3%, demonstrating excellent accuracy and precision. The proposed method was employed to quantify target analytes in actual plant samples. The accuracy of this method was not significantly different from that of the microwave digestion method. The proposed method has been demonstrated to be a valid approach for the determination of target elements in actual plant samples.

Foxtail millet [Setaria italica (L.) P. Beauv.] grown under nitrogen deficiency exhibits a lower folate contents

Foxtail millet [Setaria italica (L.) P. Beauv.], as a rich source of folates, has been cultivated on arid infertile lands, for which N deficiency is one of the major issues. Growing environments might have a significant influence on cereal folate levels. However, little is known whether N deficiency modulates cereal folate levels. In order to obtain enriched folate foxtail millet production in nutrient-poor soil, we conducted a study investigating the content of folate derivatives of 29 diverse foxtail millet cultivars under two N regimes (0 and 150 kg N ha^-1) for 2 years to explore folate potential grown under low N. The contents of total folate and most derivatives were reduced by N deficiency. The effect on total folate content caused by N was stronger than cultivar genotype did. Folate content of enriched folate cultivars was prone to be reduced by N deficiency. Structural equation models (SEMs) revealed that N fertilization had a positive indirect effect on grain folate content through influencing plant N and K accumulation. Collectively, the results indicate much more attention should be paid to N management when foxtail millet is cultivated in infertile soil, to improve foxtail millet folate contents.

Assessment of total concentration and bioaccessible fraction of minerals in peaches from different cultivars by MIP OES

This paper describes studies for the determination of total concentration and bioaccessible fraction of minerals in peaches by MIP OES. The PCA analysis identified 3 distinct groups of elements concerning the total concentration, which was attributed to the origin of each cultivar. Among the macroelements, K presented higher values for total concentration, while B and Fe predominated among the microelements. Regarding the bioaccessible fraction, Mn presented the highest percentage (46-84%), followed by Zn and B (10-63% and 33-57%, respectively). Pearson's correlation coefficient revealed that reducing sugars and titratable acidity can influence the mineral bioaccessibility, highlighting the strong positive correlations between reducing sugars with Mn and total acidity with Fe. Peach cultivars have satisfactory nutritional value, but the total and bioaccessible concentrations of minerals obtained do not meet the recommended daily needs, requiring the consumption of other fruits and vegetables to complement the diet.

Microwave-assisted digestion method using diluted nitric acid and hydrogen peroxide for the determination of major and minor elements in milk samples by ICP-OES and ICP-MS

A novel method for microwave-assisted digestion of milk samples using diluted HNO₃and H₂O₂ with a single reaction chamber was developed for elemental analysis by ICP-based techniques. The optimal conditions for digestion were 0.25 g of sample mass, 6 mL of 0.1 molL^-1HNO₃and 2 mL of 30% H₂O₂ at 250 ℃ and 160 bar. The optimized procedure resulted in low residual carbon content and residual acidity of 260 mgL^-1 and 0.06 mol L^-1, respectively. The limits of detection ranged from 0.286ոg g^-1(Ca) to 82.990ոg g^-1(Fe). In addition, the proposed method was considered an excellent green analysis method with a final score of 87 based on the analytical Eco-Scale. Finally, the method was validated and applied to the determination of Al, As, Ba, Ca, Cd, Co, Cr, Cu, Fe, Mg, Mn, Ni, Pb, Sb, Se, and Zn in milk samples from South Korea.

Optimization of Demineralization and Pyrolysis Performance of Eucalyptus Hydrothermal Pretreatment

The preparation of bio-oil through biomass pyrolysis is promoted by different demineralization processes to remove alkali and alkaline earth metal elements (AAEMs). In this study, the hydrothermal pretreatment demineralization was optimized by the response surface method. The pretreatment temperature, time and pH were the response elements, and the total dissolution rates of potassium, calcium and magnesium were the response values. The interactions of response factors for AAEMs removal were analyzed. The interaction between temperature and time was significant. The optimal AAEMs removal process was obtained with a reaction temperature of 172.98 °C, time of 59.77 min, and pH of 3.01. The optimal dissolution rate of AAEMs was 47.59%. The thermal stability of eucalyptus with and without pretreatment was analyzed by TGA. The hydrothermal pretreatment samples exhibit higher thermostability. The composition and distribution of pyrolysis products of different samples were analyzed by Py-GC/MS. The results showed that the content of sugars and high-quality bio-oil (C6, C7, C8 and C9) were 60.74% and 80.99%, respectively, by hydrothermal pretreatment. These results show that the removal of AAEMs through hydrothermal pretreatment not only improves the yield of bio-oil, but also improves the quality of bio-oil and promotes an upgrade in the quality of bio-oil.

A simple and cost-effective smartphone-based digital imaging device for the quantification of selected heavy metals in Thai rice

This paper describes smartphone-based digital imaging equipment for lead, cadmium, copper, and zinc determination in Thai rice that is both convenient and cost-effective. This smartphone-based digital imaging device has a built-in light control box made of poly(lactic acid) or PLA, a compostable and biodegradable plastic, with a light control circuit box underneath that uses a single white light-emitting diode (LED) lamp and takes photos at only 20 lux, which is very low but clearly captures the color of heavy metal complexes. In the present study, the dithizone ligand in different buffers is employed to produce a specific color solution for each heavy metal. According to the output from the free Color Name application, the concentration of heavy metals is proportional to the intensity of the resulting red color. A linear range of 0.1-1.0 mg L^-1 was obtained. The lower detection limit was determined to be between 0.01 and 0.05 mg L^-1, whereas the quantification limit was in the range from 0.04 to 0.15 mg L^-1. The intra-day precision (%RSD, n = 5) was 0.4-0.8 with high consistency, while the inter-day precision (%RSD, n = 5) was 0.5-0.8 with good efficacy. The recovery rate for heavy metals added to samples of Thai rice ranged from 99.4 to 105.5 percent. Heavy metals were detected in a variety of rice samples utilizing the smartphone-based digital imaging equipment, with acceptable accuracy when compared to atomic absorption spectrophotometric data using a paired t-test. This smartphone-based digital imaging is efficient, accessible, and cost-effective, and it provides a viable alternative to existing heavy metal detection methods in Thai rice.

Effects of the consumption of guarana on human health: A narrative review

Guarana (Paullinia cupana) is a plant from the Amazon region with cultural importance. Despite its early ancestral use by indigenous tribes, the first reports regarding the benefits of guarana consumption for human health were published in the 19th century. Since then, the use of guarana seed in powder and extract forms has been studied for its diverse effects on human health, such as stimulating, anti-inflammatory, antioxidant, anticancer, hypocholesterolemic, and anti-obesity effects. These effects are attributed to the high content of bioactive compounds found in guarana seeds, especially methylxanthines and flavonoids. In fact, the Brazilian Food Supplement Law has officially acknowledged guarana as a source of bioactive compounds. The number and diversity of studies focused on guarana and human health are increasing; thus, organizing and describing the available evidence on guarana and its applications is necessary to provide a framework for future studies. In this narrative review, we have organized the available information regarding guarana and its potential effects on human health. Guarana produces unique fruits with great potential for human health applications. However, the available evidence lacks human studies and mechanistic investigations. Future studies should be designed considering its applicability to human health, including intake levels and toxicity studies.

Applied Analytical Methods for Detecting Heavy Metals in Medicinal Plants

For thousands of years, medicinal plants (MPs) have been one of the main sources of drugs worldwide. However, recently, heavy metal pollution has seriously affected the quality and safety of MPs. Consuming MPs polluted by heavy metals such as Pb, Hg, and Cu significantly threaten the health of consumers. To manage this situation, the levels of heavy metals in MPs must be controlled. In recent years, this field has attracted significant attention, but few researchers have systematically summarized various analytical methods. Therefore, it is necessary to investigate methods that can accurately and effectively detect the amount of heavy metals in MPs. Herein, some important analytical methods used to detect heavy metals in MPs and their applications have been introduced and summarized in detail. These include atomic absorption spectrometry, atomic fluorescence spectrometry, inductively coupled plasma mass spectrometry, inductively coupled plasma atomic emission spectrometry, X-ray fluorescence spectrometry, neutron activation analysis, and anodic stripping voltammetry. The characteristics of these methods were subsequently compared and analyzed. In addition, high-performance liquid chromatography, ultraviolet spectrophotometry, and disposable electrochemical sensors have also been used for heavy metal detection in MPs. To elucidate the systematic and comprehensive information, these methods have also been briefly introduced in this review.

Chemometric tools in the optimization of a microwave-assisted digestion procedure for guarana-based drink samples and data analysis from elemental, caffeine, and epicatechin contents

In this work, a method was developed for the determination of Na, K, Ca, Mg, P, S, Fe, Zn, Mn, and Cu by ICP OES and caffeine and epicatechin by HPLC-DAD in industrialized guarana-based beverages. The acid digestion in microwave oven was optimized by constrained mixture design. The optimum volumes found for the reagents were 2.60 mL (HNO₃), 1.80 mL (H₂O₂), and 0.60 mL (HCl) for a final volume of 10 mL, resulting in a final digestate with residual acidity of 0.8 mol L^-1 and 9% for residual carbon content. The detection limits found for the studied elements were between 0.0010 and 0.050 mg L^-1. Precision (%RSD) was always below 6%. Accuracy was assessed by analyzing a certified reference material and addition and recovery tests. PCA and HCA were applied to caffeine, epicatechin and elemental concentrations aiming to evidence latent information.

Multi-level data fusion strategies for modeling three-way electrophoresis capillary and fluorescence arrays enhancing geographical and grape variety classification of wines

Capillary electrophoresis with diode array detection (CE-DAD) and multidimensional fluorescence spectroscopy (EEM) second-order data were fused and chemometrically processed for geographical and grape variety classification of wines. Multi-levels data fusion strategies on three-way data were evaluated and compared revealing their advantages/disadvantages in the classification context. Straightforward approaches based on a series of data preprocessing and feature extraction steps were developed for each studied level. Partial least square discriminant analysis (PLS-DA) and its multi-way extension (NPLS-DA) were applied to CE-DAD, EEM and fused data matrices structured as two-way and three-way arrays, respectively. Classification results achieved on each model were evaluated through global indices such as average sensitivity non-error rate and average precision. Different degrees of improvement were observed comparing the fused matrix results with those obtained using a single one, clear benefits have been demonstrated when level of data fusion increases, achieving with the high-level strategy the best classification results.

Nutritional and Physicochemical Characterization of Strychnos madagascariensis Poir (Black Monkey Orange) Seeds as a Potential Food Source

Strychnos madagascariensis Poir is an underutilized fruit that is considered a valuable food during droughts and famine. The aim of this research was to characterize the nutritional composition and the flour functional properties, for the use as a potential food source. Seed flour was analysed using a standard enzymatic assay for sugars, acid/neutral detergent analysis for fibre, ether extraction for fat and HPLC for strychnine. Results showed that the seeds contained 41% reducing sugars and 53% fibre. The mineral composition, determined using microwave-assisted acid digestion and inductively coupled plasma optical emission spectrometry (ICP-OES), showed that the seeds contained high quantities of iron (15.78 mg/100 g) and manganese (9.86 mg/100 g). The flour water absorption index (1.37 g/g) was substantially higher than that of wheat, brown rice and tapioca flours and the oil absorption index showed similarities to the reference flours (1.09 g/g). The flour peak (37,788 RVU) and final viscosities (62,928 RVU) were significantly (p < 0.001) higher than the reference flours. This study was the first to quantify the strychnine content (0.08%) in the seeds. Results suggest that the seeds have good potential for food product development; however, further processing is essential to ensure safety for consumption.

Simultaneous determination of heavy metals by an electrochemical method based on a nanocomposite consisting of fluorinated graphene and gold nanocage

Fluorinated graphene/gold nanocage (FGP/AuNC) nanocomposite was developed for simultaneous determination of heavy metals using square wave anodic stripping voltammetry. Under optimized conditions, with a buffer pH of 5.0, a deposition potential of - 1.25 V, and a deposition time of 140 s, the method can obtain the best results. The FGP/AuNC electrode exhibits low limits of detection (0.08, 0.09, 0.05, 0.19, 0.01 μg L^-1), wide linear ranges (6-7000, 4-6000, 6-5000, 4-4000, 6-5000 μg L^-1), and well-separated stripping peaks (at - 1.10, - 0.77, - 0.50, - 0.01, 0.31 V vs Ag/AgCl) towards Zn²⁺, Cd²⁺, Pb²⁺, Cu²⁺, and Hg²⁺, respectively. Furthermore, the FGP/AuNC electrode is also used for simultaneous determination of Zn²⁺, Cd²⁺, Pb²⁺, Cu²⁺, and Hg²⁺ in real samples (peanut, rape bolt, and tea). Highly consistent results are found between the electrochemical method and atomic fluorescence spectrometry/inductively coupled plasma-mass spectrometry. The method has been successfully applied to the determination of heavy metal ions in agricultural food. Graphical abstract Schematic representation of simultaneous determination of heavy metal ions by electrochemical method. The FGP/AuNC (fluorinated graphene/gold nanocage) electrode is used to simultaneous determination of Zn²⁺, Cd²⁺, Pb²⁺, Cu²⁺, and Hg²⁺ by square wave anode stripping voltammetry.

Variation of different metabolites and heavy metals in Oryza sativa L., related to chronic kidney disease of unknown etiology in Sri Lanka

Chronic Kidney Disease of Unknown Etiology (CKDu) is a serious health problem in Sri Lanka. This disease is especially seen among lowland rice cultivators. Chemical stress factors such as pesticides and heavy metals can change the chemical composition and quantities of various metabolites in plants. Therefore, in this study phenolic compounds, free amino acid content and Chromium, Cadmium, Lead contents of rice grains were determined in CKDu prevalent areas. Furthermore, Chromium, Cadmium and Lead contents of cooked rice in CKDu prevalent areas were determined because they still use well water for cooking purposes and none of studies have been conducted to investigate the heavy metal contents of cooked rice. The total flavonoid contents of rice grains in highly CKDu affected areas are comparatively lower and has a significant negative correlation with Cadmium and Chromium contents in rice grains (P < 0.05). The Chromium, Cadmium and Lead contents of raw rice have been reduced during cooking process. Therefore, these heavy metal contents in cooking water are not sufficient to increase those heavy metal contents in cooked rice. However, the weekly intake of Chromium through cooked rice in CKDu prevalent area is higher than Povisional Tolerable Weekly Intake (PTWI) and weekly intake of Cadmium can exceed the PTWI with other foods rich with Cadmium. Therefore, this study suggested that total flavonoid content in rice grains is a important variation factor of CKDu prevalence and the chronic intake of Chromium and Cadmium contents may result kidney failure.

Copper nanoclusters @ nitrogen-doped carbon quantum dots-based ratiometric fluorescence probe for lead (II) ions detection in porphyra

A novel ratiometric fluorescence probe was proposed for detecting lead (II) ions (Pb²⁺) in porphyra, the approach was based on copper nanoclusters and nitrogen-doped carbon quantum dots (CuNCs-CNQDs). In this probe, the CuNCs delivered the response signal, the fluorescence of which was enhanced by Pb²⁺ due to the aggregation-induced emission enhancement (AIEE) between Pb²⁺ and CuNCs. The CNQDs provided the self-calibration signal, whose fluorescence remained almost unchanged in coexistence with Pb²⁺. According to the change of fluorescence intensity ratio between the fluorophores, CuNCs-CNQDs nanohybrid was used as ratiometric probes for the sensitive detection of Pb²⁺ in the range of 0.010-2.5 mg L^-1, with a detection limit of 0.0031 mg L^-1. Finally, the probe was successfully applied to detect Pb²⁺ in porphyra with relative standard deviations (RSDs) lower than 5%. This study provides a straightforward, stable, and sensitive approach for detecting Pb²⁺ in porphyra.