Determination of Trace and Major Elements in Vegan Milk and Oils by ICP-OES After Microwave Digestion

Analysis of heavy metals and minerals in edible vegetable oils produced and marketed in Gondar City, Northwest Ethiopia

INTRODUCTION

Nowadays, food safety is regarded as one of the most critical global public health issues. Edible oil, a key ingredient in food processing, is widely used and consumed in every Ethiopian household. However, its safety is often overlooked. Currently, edible oil is produced in Ethiopia from small-scale operations to large industrial levels, as well as imported from other countries.

OBJECTIVE

This study aimed to determine the levels of heavy metals and essential minerals in edible vegetable oils produced and marketed in Gondar City, Northwest Ethiopia.

METHODS

A laboratory-based cross-sectional study was conducted from May to July 2021 in Gondar City. Seventeen edible oil samples were collected using simple random sampling techniques. Heavy metal content was determined using an atomic absorption spectrophotometer with the standard procedures and techniques after microwave digestion. The efficiency and validity of the method used were evaluated by determining the limit of detection (LOD), the limit of quantification (LOQ), accuracy, and precision. The collected data were entered into Microsoft Excel and transported to Stata for analysis.

RESULT

A total of seventeen vegetable oil samples were analyzed. The accuracy of the method was evaluated by recovery studies, which ranged from 81 to 115%, and the relative standard deviations were found to be below 15%. The concentrations of Zn, Cu, Fe, Cd, and Pb were in the range of 0.07 to 0.8 mg/l, 0.002 to 0.06 mg/l, 0.01 to 0.8 mg/l, 0.08 to 0.18 mg/l, and 0.003 to 0.27 mg/l, respectively. In general, the lead and cadmium content was higher than other metals in some of the investigated edible vegetable oils. Most values fell within the permissible quality limits for edibility as prescribed by the World Health Organization (WHO) and the National Agency for Food and Drug Administration and Control (NAFDAC). However, the levels of Pb and Cd exceeded the reference levels in some locally produced vegetable oils.

CONCLUSION

To address the exceeded levels of heavy metals, it is imperative to implement more careful handling, processing of raw materials, and filtering practices. Producers and marketers should take the necessary precautions to prevent contamination. Strict regulatory control from responsible bodies and stakeholders is recommended to ensure the safety and metal contents of vegetable oils originating from the study area.

Assessment of carcinogenic and non-carcinogenic risk of exposure to potentially toxic elements in tea infusions: Determination by ICP-OES and multivariate statistical data analysis

BACKGROUND

The perennial evergreen tea (Camellia sinensis) plant is one of the most popular nonalcoholic drinks in the world. Fertilizers and industrial, agricultural, and municipal activities are the usual drivers of soil contamination, contaminating tea plants with potentially toxic elements (PTEs). These elements might potentially accumulate to larger amounts in the leaves of plants after being taken up from the soil. Thus, frequent monitoring of these elements is critically important.

METHODS

The present study intended to determine PTEs (Al, Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd, and Pb) in both tea leaves and infusions using ICP-OES. Various multivariate data analysis methods such as principal component analysis (PCA) and hierarchical cluster analysis (HCA) were employed to elucidate the potential sources of PTEs contamination, whether from anthropogenic activities or natural origins. Additionally, Pearson's correlation coefficient (PCC) was calculated to assess the relationships between the variables under study.

RESULTS

The mean contents (mg/L) of all studied elements in tea infusions decreased in order Mn (150.59 ± 1.66) > Fe (11.39 ± 0.99) > Zn (6.62 ± 0.89) > Cu (5.86 ± 0.62) > Co (3.25 ± 0.64) > Ni (1.69 ± 0.23) > Pb (1.08 ± 0.16) > Cr (0.57 ± 0.09) > Cd (0.46 ± 0.09) > Al (0.05 ± 0.008), indicating that Mn exhibits the highest abundance. The mean concentration trend in tea leaf samples mirrored that of infusions, albeit with higher concentrations of PTEs in the former. The tolerable dietary intake (TDI) value for Ni and provisional tolerable monthly intake (PTMI) value for Cd surpassed the standards set by the WHO and EFSA. Calculated hazard index (HI < 1) and cumulative cancer risk (CCR) values suggest negligible exposure risk.

CONCLUSION

Elevated levels of PTEs in commonly consumed tea products concern the public and regulatory agencies.

Evaluation of Alternative Sources of Proteins and Other Nutrients with Potential Applications in Fish Nutrition

The European Union's (EU) agricultural self-sufficiency is challenged by its reliance on imported plant proteins, particularly soy from the Americas, contributing to deforestation and greenhouse gas emissions. Addressing the EU's protein deficit, this study evaluates alternative protein sources for aquaculture, focusing on their nutritional value, elemental content, and polycyclic aromatic hydrocarbons (PAHs). Protein flours from gastropods (Helix pomatia, Arion lusitanicus, Arion vulgaris) and their hepatopancreas, along with plant-based proteins from food industry by-products (oilcakes, coffee grounds, spent brewer's yeast), were analyzed. Results revealed that snail flour contained the highest protein content at 59.09%, significantly outperforming hepatopancreas flour at 42.26%. Plant-based proteins demonstrated substantial nutritional value, with coffee grounds flour exhibiting a remarkable protein content of 71.8% and spent brewer's yeast flour at 57.9%. Elemental analysis indicated high levels of essential minerals such as magnesium in hepatopancreas flour (5719.10 mg/kg) and calcium in slug flour (48,640.11 mg/kg). However, cadmium levels in hepatopancreas flour (11.45 mg/kg) necessitate caution due to potential health risks. PAH concentrations were low across all samples, with the highest total PAH content observed in hepatopancreas flour at 0.0353 µg/kg, suggesting minimal risk of PAH-related toxicity. The analysis of plant-based protein sources, particularly oilcakes derived from sunflower, hemp, flax, and pumpkin seeds, revealed that these by-products not only exhibit high protein contents but present a promising avenue for enhancing the nutritional quality of feed. This study underscores the potential of utilizing gastropod and plant-based by-products as sustainable and nutritionally adequate alternatives to conventional feeds in aquaculture, contributing to the EU's environmental sustainability goals.

Selenium in plant-based beverages: Total content, estimated bioaccessibility and contribution to daily intake

BACKGROUND

The search for alternative protein sources has increased the consumption and commercialization of plant-based beverages (PBBs). This study aimed to determine the total Se content, estimate the bioaccessibility of selenium (Se) in commercial PBBs derived from different raw materials, and evaluate their contribution to the reference daily intake (RDI).

METHODS

An ultrasound assisted acid digestion method and ICP-MS was used to determine Se, and the INFOGEST method to estimate the bioaccessible percentages. Validation of this method was also performed, and the parameters obtained were: LOD and LOQ were 2.1 and 4.0 µg/kg, respectively. For accuracy, recovery percentages ranged from 99 % and 111 % (certified reference materials), and 95 % and 101 % (spiked experiments for bioaccessible extracts as recoveries).

RESULTS

The PBBs presented total Se content between 4 and 226 µg/kg. Bioaccessible percentages ranged from 63.5 % (mix of plant sources) to 95.9 % (produced with organic cashew nuts). Only one cashew nut PBBs supplied the daily demand of Se, representing 64.6 %, 75.3 % and 82.2 % of the RDI; for lactating and pregnant women, children (≥ 4 years) and adults, respectively.

CONCLUSIONS

The Se determination method through acid digestion assisted by ultrasound and ICP-MS was considered adequate for the PBBs samples. Se content varied according to the raw material used in sample preparation. High percentages (> 60 %) of bioaccessibility were observed and only one PBBs derived from organic cashew nuts supplied the recommended Se demand for different groups of individuals.

A systematic review and meta-analysis of validated analytical techniques for the determination of total selenium in foods and beverages

The intricate balance between the beneficial and harmful effects of selenium (Se) intake means that its quantification in food needs to be done correctly. Therefore, in this review, we systematized 105 articles to identify the most studied methodologies, analytical techniques, and food matrices. Among the analytical techniques employed, inductively coupled plasma mass spectrometry (ICP-MS) (n = 29) emerged as the most commonly used method. The most prevalent hydrolysis methodology to digest Se in food matrices involved the use of nitric acid combined with ultrasound, which improved both the yield and digestion time. Optimal recovery values were achieved when total Se quantification accounted for the sum of Se(IV) and Se(VI) (94.4-99.4%) and for SeCys (88-96.5%). These findings are relevant for advancing methodological approaches, and their results emphasize the importance of developing alternative, faster, and lower-cost protocols for Se quantification in foods and beverages.

Analysis of Eight Types of Plant-based Milk Alternatives from the United States Market for Target Minerals and Trace Elements

A wide variety of commercial plant-based foods that are marketed and sold as alternatives for milk (plant-based milk alternatives or PBMAs) are available to consumers. In this study, PBMAs from the United States (n=85) were subjected to analysis for target minerals (magnesium, phosphorus, selenium, and zinc) to compare their variability across PBMA types, brands, and production lots. Samples were also screened for the environmental contaminant elements arsenic, cadmium, and lead. The eight PBMA types sampled were produced from almond, cashew, coconut, hemp, oat, pea, rice, and soy. Elemental analysis was conducted using microwave-assisted acid digestion followed by inductively coupled plasma-mass spectrometry. The results showed that pea PBMAs contained the highest mean amounts of phosphorus, selenium, and zinc, while soy PBMAs were highest in magnesium. Mean amounts of minerals were lower than those found in milk for the majority of PBMA types. There was significant variation (P<0.05) in amounts of minerals across the majority of product brands. The amounts of phosphorus and magnesium varied across production lots (P<0.05), but the absolute value of these differences was low. Total arsenic was highest in rice PBMAs; amounts of cadmium and lead across PBMAs were generally found at low or non-quantifiable amounts. These results underscore the importance of generating analytical data on the elemental composition of products within the rapidly growing category of PBMA.

Potentially Toxic Elements (PTEs) in Refined and Cold-Pressed Vegetable Oils Distributed in Ahvaz, Iran: a Probabilistic Health Risk Assessment

The concentration of potentially toxic elements (PTEs) in vegetable oils using inductively coupled plasma-optical emission spectrometry (ICP-OES) was measured. Probabilistic non-carcinogenic risk in consumers was estimated using the target hazard quotient (THQ) and total target hazard quotient (TTHQ) by Monte Carlo simulation (MCS) method. The highest content of PTEs was found in blend oil for As (0.39 ± 0.07 mg/L), in cold-pressed rapeseed oil for Cd and Cu (0.07 ± 0 and 0.40 ± 0.06 mg/L) respectively, in cold-pressed sunflower oil for Fe (0.15 ± 0.10 mg/L), in refined sesame oil for Ni and Pb (0.44 ± 0.07 and 0.65 ± 0.07 mg/L, respectively), and in cold-pressed sunflower and rapeseed oils for Zn (0.19 ± 0.04 mg/L). THQ in adults and children due to individual vegetable oils (cold-pressed and refined vegetable oil) was lower than 1 value. TTHQ in adults and children due to consumption of cold-pressed vegetable oils was 0.05 and 0.26, and also refined vegetable oil was 0.51 and 0.33, respectively. TTHQ due to consumption of both types of oils was less than 1; therefore, the population is not at risk of non-carcinogenicity.

Assessment of the Accuracy of Nutrition Label and Chemical Composition of Plant-Based Milks Available on the Italian Market

Growing health, environmental, and ethical concerns have encouraged interest in plant-based milks (PBMs), but it remains questionable whether the nutrition labeling of these products is adequately reliable for consumers, and whether nutritional standards can be defined for a given PBM type. On this basis, cereal, pseudocereal, nut, and legume PBMs available on the Italian market were analyzed in order to check the accuracy of nutritional labels on packages and generate new or updated compositional data. Most labels provided inaccurate information, especially with respect to the declared energy, fat, and saturated fat. Cereal- and pseudocereal-based PBMs were generally characterized by high MUFA (34.04-59.35%) and PUFA (21.61-52.27%). Almond, soy, rice, and hazelnut beverages displayed the highest levels of total tocopherols (11.29-13.68 mg/L), while buckwheat and spelt PBMs had the highest total polyphenol content (34.25-52.27 mg GAE/100 mL). Major and trace elements greatly varied among samples, being more abundant in buckwheat and coconut-based drinks. A PCA confirmed that nutritional standards cannot be unequivocally established for a given PBM, and indicated that, among the investigated variables, inorganic elements had more weight in the sample differentiation. Overall, to reliably guide consumers in their dietary choices, there is a need for greater accuracy in the development of nutrition labels for PBMs, as well as greater effort in assessing the nutritional quality of the ever-increasing variety of products available on the market.

Mercury Exposure from the Consumption of Dietary Supplements Containing Vegetable, Cod Liver, and Shark Liver Oils

Vegetable and fish oils constitute a significant part of all dietary supplements. Due to increasing environmental pollution, the raw materials used for their production may be contaminated with toxic substances, including metals. The aim of the present study was to determine the mercury (Hg) content in vegetable oils, shark liver oils, and cod liver oils. The tests conducted were to help determine the level of mercury contamination of the tested preparations and the related potential threat to human health. The amount of Hg in the tested dietary supplements was compared, and the amount of the metal consumed at various times of use was determined. A total of 36 preparations of dietary supplements available on the Polish market were used for the study. The method of atomic absorption spectrometry using the amalgamation technique was used for the determinations (AMA 254, Altec, Czech Republic). Among the sample of all of the tested preparations, the Hg concentration ranged from 0.023 to 0.427 µg/kg, with an average of 0.165 µg/kg. Differences in Hg content in the various tested preparations (shark liver oil, cod liver oil, and vegetable oils) were statistically significant. The average concentration of Hg in the vegetable oils (0.218 µg/kg) was more than twice that of the cod liver oils (0.106 µg/kg) and shark liver oils (0.065 µg/kg). In none of the tested preparations did the amount of Hg exceed the acceptable standard for dietary supplements (0.10 mg/kg). The analysis showed that the Hg content in vegetable oils, shark liver oils, and fish oils from the Polish market is at a low level, guaranteeing the safety of their use, and as such, they do not pose a threat to health.

Market Basket Survey of the Micronutrients Vitamin A, Vitamin D, Calcium, and Potassium in Eight Types of Commercial Plant-Based Milk Alternatives from United States Markets

We performed a market basket survey of plant-based milk alternatives (PBMAs) from the US market for vitamin A, vitamin D, calcium, and potassium to identify the amount and variability of these micronutrients across various PBMAs. The PBMA types included in this analysis were almond, cashew, coconut, hemp, oat, pea, rice, and soy (n=90 total product units). Analyses for vitamin A (as retinyl palmitate), vitamin D2/D3, and minerals were performed using high-performance liquid chromatography, liquid chromatography-tandem mass spectrometry, and inductively coupled plasma-mass spectrometry, respectively. A majority of PBMA types had significant differences (P<0.05) in the amounts of target micronutrients across brands. The coefficient of variation (%CV) for micronutrient concentrations within one lot of a single brand ranged from 4.1-42.2% for vitamin A, 1.5-44.1% for vitamin D, 1.7%-37.6% for calcium, and 0.7%-39.0% for potassium. The variability of these micronutrients should be taken into account when considering the nutritional value of PBMAs.

Evaluating the influence of cold plasma bubbling on protein structure and allergenicity in sesame milk

BACKGROUND

Sesame is a traditional oilseed comprising essential amino acids. However, the presence of allergens in sesame is a significant problem in its consumption; thus, this study attempted to reduce these allergens in sesame oilseeds.

OBJECTIVE

The present study aimed to evaluate the effect of cold plasma processing on structural changes in proteins, and thereby the alteration of allergenicity in sesame milk. Method: Sesame milk (300 mL) was processed using atmospheric pressure plasma bubbling unit (dielectric barrier discharge, power: 200 V, and airflow rate: 16.6 mL/min) at different exposure times (10, 20, and 30 min).

RESULTS

The efficiency of plasma-bubbling unit as measured by electron paramagnetic resonance in terms of producing reactive hydroxyl (OH) radicals proved that generation of reactive species increased with exposure time. Further, the plasma-processed sesame milk subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis and differential scanning calorimetery analysis revealed that plasma bubbling increased the oxidation of proteins with respect to bubbling time. The structural analysis by Fourier transform infrared spectroscopy and circular dichroism revealed that the secondary structure of proteins was altered after plasma application. This change in the protein structure helped in changing the immunoglobulin E (IgE)-binding epitopes of the protein, which in turn reduced the allergen-binding capacity by 23% at 20-min plasma bubbling as determined by the sandwich-type enzyme-linked immunosorbent assay. However, 30-min plasma bubbling intended to increase allergenicity, possibly because of increase in IgE binding due to the generation of neo epitopes.

CONCLUSION

These changes proved that plasma bubbling is a promising technology in oxidizing protein structure, and thereby reducing the allergenicity of sesame milk. However, increase in binding at 30-min bubbling is to be studied to facilitate further reduction of the binding capacity of IgE antibodies.

Investigation of Trace Elements in Vegan Foods by ICP-MS After Microwave Digestion

Veganism is gaining popularity around the world day by day. Vegan nutrition is a diet in which not all animal foods are used. A vegan diet does not contain meat, fish, milk and dairy products, and eggs and consists of vegetables, fruits, grains, legumes, and nuts. Vegan diets maintain energy balances in a wide variety of plant foods. So, health problems can be seen due to nutrient and mineral deficiencies in the long-term continuation of the vegan diet. Due to insufficient intake of vitamins and minerals such as vitamin D, vitamin B12, calcium, iron, and zinc, energy and protein balance in the body may not be achieved by vegan individuals. The contents of aluminum, chromium, manganese, iron, cobalt, nickel, copper, zinc, arsenic, mercury, cadmium, and lead have been analyzed by inductively coupled plasma mass spectrometer (ICP-MS) in 10 different vegan foods purchased from Turkey. Certified reference material (1547 peach leaves) was used for validating the digestion procedure. Dry, wet, and microwave processes were compared, and it was found that the microwave digestion method was the best. Element levels in the analyzed samples were found below the legal limits. The purpose of this work is to investigate the trace element content of various foods used in vegan nutrition.

Geochemical Analysis of Cretaceous Shales from the Hazara Basin, Pakistan: Provenance Signatures and Paleo-Weathering Conditions

The geochemical investigation of shales from the Early to Middle Cretaceous Chichali Formation in the Hazara Basin was conducted to determine the origin, tectonic setting and evolution, paleo-weathering conditions, and paleo-oceanographic reconstruction. The research included a comprehensive field survey, sample collection, and analysis of a variety of main, trace, and rare-earth elements using an X-ray fluorescence spectrometer (XRF). Bivariate plots and ternary diagrams were used to determine the provenance, tectonic setting, and paleo-weathering conditions that existed during the development of the Chichali Formation in the Hazara Basin. The values of Ba/Sc, Ba/Co, Th/Sc, Cr/Th, Cr/Zr, Th/Co, Th/Cr, Sc/Th, bivariate plots of Al2O3 vs. TiO2, TiO2 vs. Zr, TiO2 vs. Ni, Df1–Df2, Zr vs. Nb, and La/Sc vs. Th/Co, and ternary diagram of K2O–Fe2O3–Al2O3 were used to illustrate the passive continental margin setting of Chichali Formation shales. The detailed chemical analysis also provides an understanding of the marine geochemical cycle, which reflects the origin of these sediments. The average K2O/Al2O3 value is less than 0.4, indicating that the shale contains clay minerals. The Chichali Formation’s Chemical Index of Alteration (mean = 71) and Index of Compositional Variation (mean = 1.12) values show a modest degree of chemical weathering in the source locations. From an environmental standpoint, the Chichali Formation is richer in toxic elements such as Ba, Zn, Ni, Cr, and Cu, which may be damaging to agricultural soils and drinking water when present in excess. These metals are incorporated into the formation during the weathering process.

Selenium in Brazil nuts: An overview of agronomical aspects, recent trends in analytical chemistry, and health outcomes

Se is an essential element in mammals. We review how its bioavailability in soil and the ability of plants to accumulate Se in foods depends on the soil Se profile (including levels and formats), besides to describe how the various selenoproteins have important biochemical functions in the body and directly impact human health. Owing to its favorable characteristics, the scientific community has investigated selenomethionine in most nut matrices. Among nuts, Brazil nuts have been highlighted as one of the richest sources of bioavailable Se. We summarize the most commonly used analytical methods for Se species and total Se determination in nuts. We also discuss the chemical forms of Se metabolized by mammals, human biochemistry and health outcomes from daily dietary intake of Se from Brazil nuts. These findings may facilitate the understanding of the importance of adequate dietary Se intake and enable researchers to define methods to determine Se species.

Development and Validation of an ICP-AES Method for the Determination of Toxic and Nutrient Metals in Candies: Application for the Analysis of Different Samples from the Greek Market

In this study, we present the development and validation of an inductively coupled plasma-atomic emission spectrometric (ICP-AES) method for the determination of Ag, Ba, Bi, Ca, Cd, Co, Cr, Cu, Fe, Mg, Mn, Ni, Pb and Zn in different candies. Various wet digestion protocols were examined in order to ensure minimum consumption of chemicals and sample preparation time. Under optimized conditions, less than 10 min were required for complete sample decomposition. The ICP-AES method was validated in terms of linearity, accuracy, precision, limits of detection (LODs) and limits of quantification (LOQs). The relative recoveries for the proposed method ranged between 80.0% and 119.0%, while the relative standard deviation values were lower than 9.0%, indicating good method accuracy and precision, respectively. The LODs for the examined analytes were 0.04–2.25 mg kg−1. Finally, the proposed method was successfully employed for the analysis of hard candies, jellies and lollipops that are sold in the Greek market, which are highly likely to be consumed by children.

Human exposure assessment to potentially toxic elements (PTEs) from tofu consumption

Potentially toxic elements (PTEs) (V, B, Ba, Li, Sr, Cr, Ni, Al, Pb, Cd) were determined in 130 samples of different tofu types (natural, flavored, smoked, and fresh made) by ICP-OES (inductively coupled plasma optical emission spectrometry). Al was the most notable element found with the highest concentration (6.71 mg/kg ww) found in flavored tofu. Ni level (0.38 mg/kg) stands out in smoked tofu. European tofu has higher PTE levels than Chinese tofu. Organic-produced tofu has higher PTE concentrations than conventional produced tofu. A total of 200 g/day of smoked tofu confers a contribution percentage of 39.6% of its TDI (tolerable daily intake). In addition, 200 g/day of flavored tofu would mean a high Pb contribution with a 23.2% of the BMDL (benchmark dose level) set in 0.63 μg/kg bw/day to the development of nephrotoxicity. Mean consumption would not pose a risk to adults' health. Considering the obtained results, it would be advisable to establish limits for certain metals such as Pb, Al, and Ni in this type of product. Furthermore, it is recommendable to set consumer guidelines to some tofu types in order to avoid excessive intake of PTEs.