Search Results (85)

The efficient recovery of rhenium (Re), a critical metal in high-tech industries, is essential to address its growing demand and reduce reliance on primary mining. In this study, we developed novel anion-exchange resins for the selective adsorption and recovery of Re(VII) ions from acidic solutions, simulating industrial by-products. The resins were synthesized from a vinylbenzyl chloride-co-divinylbenzene copolymer modified with aliphatic, heterocyclic, and aromatic weakly basic amines, selected from among bis(3-aminopropyl)amine (BAPA), 1-(2-pyrimidinyl)piperazine (PIP), thiosemicarbazide (TSC), 2-amino-3-hydroxypyridine (AHP), 1-(2-hydroxyethyl)piperazine (HEP), 4-amino-2,6-dihydroxypyrimidine (AHPI), and 2-thiazolamine (TA). The adsorption of Re on BAPA, PIP, and HEP resins obeyed the Langmuir model, and the resins exhibited high adsorption capacities, with maximum values reaching 435.4 mg Re g⁻¹ at pH 6. Furthermore, strong selectivity for ReO₄⁻ ions over competing species, including Mo, Cu, and V, was noted in solutions simulating the leachates of the by-products of Cu-Mo ores. Additionally, complete elution of Re was possible. The developed resins turned out to be highly suitable for the continuous-flow-mode adsorption of ReO₄⁻, revealing outstanding adsorption capacities before reaching column breakthrough. In this context, the novel anion-exchange resins developed offer a reference for further Re recovery strategies. Full article

Thermal-processed foods like baked, smoked, and fried products are popular for their unique aroma, taste, and color. However, thermal processing can generate various contaminants via Maillard reaction, lipid oxidation, and thermal degradation, negatively impacting human health. This review summarizes the formation pathways, influencing factors, and tracing approaches of potential hazards in thermally processed foods, such as polycyclic aromatic hydrocarbons (PAHs), heterocyclic aromatic amines (HAAs), furan, acrylamide (AA), trans fatty acids (TFAs), advanced glycation end-products (AGEs), sterol oxide. The formation pathways are explored through understanding high free radical activity and multiple active intermediates. Control patterns are uncovered by adjusting processing conditions and food composition and adding antioxidants, aiming to inhibit hazards and enhance the safety of thermal-processed foods. Full article

The objectives of this study were to develop a coated gluten-free chicken liver product that could be consumed by a wide range of consumer groups and to investigate the quality characteristics and heterocyclic aromatic amine (HCA) compounds. The effects of three different formulations (thyme, turmeric, and control) and two different cooking methods (deep-frying and oven cooking) on the physical, chemical, microbiological, and sensorial characteristics and HCA compounds of samples, which were stored at −20 °C for 60 days, were investigated. TBARS values were lower in the oven-cooked samples than in the deep-fried samples at the end of the storage, with turmeric proving most effective (p < 0.05). TMAB and total HCA were lower in thyme and turmeric-added samples than in the control samples (p < 0.05). The total HCA content of the deep-fried and oven-cooked samples decreased by 14.42% and 13.20% with the addition of thyme and by 18.75% and 23.35% with the addition of turmeric, respectively. The oven-cooked sample with turmeric was stored for 60 days without any significant changes in the color, flavor, and overall acceptance according to the beginning of the storage (p > 0.05). In conclusion, gluten-free oven-cooked turmeric-added coated chicken liver can be a healthy food alternative in the market. Full article

Heterocyclic aromatic amines (HAAs), known for their mutagenic and carcinogenic potential, are formed during the heating of protein-rich food items. Detecting HAAs swiftly and accurately poses challenges due to complex food matrices and low HAA concentrations. In this study, a simple and efficient magnetic solid-phase extraction (MSPE) strategy was developed for the simultaneous isolation and enrichment of three HAAs such as 2-amino-3,4,8-trimethylimidazo [4,5-f]quinoxaline (4,8-DiMeIQx), 2-amino-3,8-dimethylimidazo [4,5-f]quinoxaline (MeIQx), and 2-amino-3-methylimidazo [4,5-f]quinoline (IQ) in processed meats, employing the magnetic covalent organic framework Fe₃O₄@MOF-545-AMSA as an adsorbent. It was synthesized via a solvothermal method, with Fe₃O₄ as the magnetic core. Its building blocks are as follows: zirconium (Zr) as the coordination metal ion, tetrakis(4-carboxyphenyl)porphyrin and benzoic acid as organic ligands, and aminomethanesulfonic acid (AMSA). This composite captures targeted HAAs efficiently by exploiting the unique porous MOF-545-AMSA structure, specific metal–ligand coordination, and AMSA’s amino and sulfonic acid groups. The quantification of HAAs was achieved through the combination of Ultra-Performance Liquid Chromatography–Tandem Mass Spectrometry (UPLC-MS/MS) and MSPE, demonstrating satisfactory linearity (R² ≥ 0.9917), high recovery rates (83.7–111.0%), and low detection limits (0.1–1.0 μg/kg). Moreover, an automated high-throughput detection system was developed using MSPE to assess the presence of HAAs in meat products. Full article

This article investigated the composition and content of volatile organic compounds (VOCs) in cumin from three Xinjiang origins (Hami, Turpan, and Hetian) at different processing temperatures. VOCs varied with temperature and origin, but alcohols and terpenes were predominant in all samples. Hetian cumin exhibited the highest VOC content and stability under specific treatments, divided into an ambient temperature treatment (AMB) and a 70 °C heat treatment. A cluster analysis revealed high similarity between replicates and significant differences among the samples. A Venn diagram comparison showed that 70 °C processing reduced the number of common VOCs among the three origins from 36 to 19, which is a decrease of 47.22%, indicating a significant impact of heating on cumin VOCs and possibly promoting the formation of new compounds. Finally, utilizing the varying abilities of different types of polyphenols to inhibit heterocyclic aromatic amines (HAAs), six polyphenolic compounds, identified as sesamin, 6-caffeoylsucrose, apigenin, eschweilenol C, kaempferol glucuronide, and luteolin, were preliminarily determined to play an active role in the β-carboline HAA simulation system. Full article

Frequent consumption of processed meat has been classified as carcinogenic to humans by the International Agency for Research on Cancer (Group 1), while red meat has been classified as probably carcinogenic (Group 2A). Mutagenic and carcinogenic compounds formed by heating in protein-rich food include, among others, heterocyclic aromatic amines (HAAs). Modifying the heat treatment of meat and using natural additives with antioxidant properties can lead to a reduction in their formation. The aim of this study was to determine polar HAAs (imidazoquinolines, IQ and MeIQ; imidazoquinoxalines, 8-MeIQx and 4,8-DiMeIQx; and phenylimidazopyridine, PhIP) in pork loin prepared without additives and with three types of dried fruit (apricots, cranberries, and prunes), baked in a roasting bag. HAAs were isolated from meat samples by solid-phase extraction. Quantitative analysis was performed by high-performance liquid chromatography with fluorescence detection (FLD) and a diode array detector (DAD). Only two HAAs, 8-MeIQx and PhIP, were detected in extracts isolated from meat samples. The total content of these compounds in meat roasted without additives was 5.9 ng/g. Using a dried fruit stuffing content of 200 g/kg of meat reduced these concentrations in dishes prepared with prunes, apricots, and cranberries by 42%, 47%, and 77%, respectively. Full article

Background: Black tea processing conditions significantly affect the final taste and flavor profiles, so researchers are now focusing on developing equipment and improving the appropriate processing conditions of major black tea varieties. Methods: Here, we tested the effect of four different initial drying temperatures, i.e., R65 (65 °C), R85 (85 °C), R105 (105 °C), and R125 (125 °C), on the sensory and biochemical profiles and volatilome of the black tea variety “Lishui wild” (LWV). Results: Our results indicate that both 85 and 105 °C are better than 65 and 125 °C for initial drying for 20 min. R105 had the highest sensory evaluation scores due to better shape, aroma, taste, leaf base, thearubigins, theanine, caffeine, and ratio of theaflavins + thearubigins to theaflavins. Both R85 and R105 had higher catechins than R65 and R125. The LWV volatilome consisted of esters (19.89%), terpenoids (18.95%), ketones (11.3%), heterocyclic compounds (9.99%), and alcohols (8.59%). In general, acids, aldehydes, amines, aromatics, ethers, hydrocarbons, phenols, sulfur compounds, and terpenoids accumulated in higher amounts in R85 and R105. The highly accumulated compounds in R105 were associated with green, fruity, sweet, woody, floral, hawthorn, mild, nutty, powdery, rose, and rosy flavors. The main pathways affected are secondary metabolites, sesquiterpenoid and triterpenoid biosynthesis, glycerolipid metabolism, zeatin biosynthesis, phenylpropanoid biosynthesis, ABC transport, glutathione metabolism, etc. Therefore, R105 can be used to achieve the optimal taste, flavor, and aroma of LWV. Conclusions: Overall, the presented data can be used by the tea industry for processing black tea with the most optimum volatile substances, catechins, theanine, amino acids, and other compounds. Full article

A new approach to 1,2,5-trisubstituted 1H-indole-3-carboxylic esters has been developed and studied. The method begins with the preparation of imines from aldehyde and primary amine derivatives. Treatment of these imines with the K₂CO₃-derived anion from methyl 2-(2-fluoro-5-nitrophenyl)acetate or methyl 2-(5-cyano-2-fluorophenyl)acetate in DMF initiates a [3+2] cyclization by addition of the anion to the imine followed by ring closure of the adduct nitrogen to the activated aromatic moiety via an S_NAr process. Twenty-one examples are reported. Temperatures required for the conversion range from 90 to 95 °C for the nitro-activated substrates to 125 to 130 °C for the cyano-activated precursors. Though efficient and atom economical, limitations arise from steric hindrance in the reacting partners. The initial indoline formed is not observed but instead undergoes spontaneous air oxidation to the give the aromatic heterocycle. Imines from nonaromatic aldehydes and amines are also possible, but these give slightly lower yields of 1H-indoles and only react with the nitro-activated substrates. The results are presented with a discussion of the mechanism and the factors important to the success of the reaction. Full article

Heterocyclic aromatic amines (HAAs), formed during the cooking of meat, are potential human carcinogens, underscoring the need for long-lived biomarkers to assess exposure and cancer risk. Frequent consumption of well-done meats containing 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), a prevalent HAA that is a prostatic carcinogen in rodents and DNA-damaging agent in human prostate cells, has been linked to aggressive prostate cancer (PC) pathology. African American (AA) men face nearly twice the risk for developing and dying from PC compared to White men. We previously demonstrated that scalp hair is a reliable biospecimen for measuring PhIP intake using liquid chromatography-mass spectrometry. This study aimed to determine whether PhIP dietary intake is higher in AA men, potentially contributing to this health disparity. Healthy AA men were found to have a significantly higher mean hair PhIP level (2.12-fold) than White men on free-choice diets. However, this difference was not statistically significant after adjusting for melanin content. Further research is needed to understand how hair pigmentation, follicular density, and other morphological features of hair influence PhIP accumulation. These insights can improve the accuracy of using hair PhIP levels as a biomarker for exposure and its potential associations with cancer risk. Full article

In the present work, inexpensive and commercially available diethyltriamine pentaacetic acid (DTPA) was used as an initiator to catalyze the N-formylation reaction of CO₂ with amines via the construction of C-N bonds in the presence of xanthone as the photosensitizer and PhSiH₃ as the reducing agent. After a systematic study of various factors, the optimal conditions for the photocatalytic reaction were obtained: 2.5 mmol of amine, 2.5 mmol of PhSiH₃, 10 mol% of DTPA, 20 mol% of xanthone, 1 mL of dimethylsulfoxide (DMSO), atmospheric pressure, and 35 W UV lamp irradiation for 48 h. Under the optimal conditions, the catalyst system afforded high performance for the N-formylation of amines (primary and secondary amines) and CO₂, and the yields of the N-formylated products of dialkylamines were above 70%. Further studies exhibit that the catalytic system has a wide scope of substrate applications. For various alicyclic secondary amines, heterocyclic secondary amines, aliphatic primary amines, and aromatic primary amines, the corresponding N-formylation products can be obtained efficiently. In addition, the catalyst can be recycled by simple precipitation and filtration. After five cycles of recycling, there was no significant change in the catalytic and structural properties of DTPA. Finally, a possible reaction mechanism is proposed. Full article

Borane–trimethylamine complex (Me₃N·BH₃; BTM) is the most stable of the amine–borane complexes that are commercially available, and it is cost-effective. It is a valuable reagent in organic chemistry with applications in the reduction of carbonyl groups and carbon–nitrogen double bond reduction, with considerable examples in the reduction of oximes, hydrazones and azines. The transfer hydrogenation of aromatic N-heterocycles and the selective N-monomethylation of primary anilines are further examples of recent applications, whereas the reduction of nitrobenzenes to anilines and the reductive deprotection of N-tritylamines are useful tools in the organic synthesis. Moreover, BTM is the main reagent in the regioselective cleavage of cyclic acetals, a reaction of great importance for carbohydrate chemistry. Recent innovative applications of BTM, such as CO₂ utilization as feedstock and radical chemistry by photocatalysis, have extended their usefulness in new reactions. The present review is focused on the applications of borane–trimethylamine complex as a reagent in organic synthesis and has not been covered in previous reviews regarding amine–borane complexes. Full article

The International Agency for Research on Cancer has classified the consumption of heat-processed meat as a direct human carcinogen and the consumption of red meat as a probable carcinogen. Mutagenic and carcinogenic compounds present in meat dishes include, among others, polycyclic aromatic hydrocarbons (PAHs) and heterocyclic aromatic amines (HAAs). These compounds can cause the development of gastrointestinal cancer. Oral cancer is one of the world’s research priorities due to the ever-increasing incidence rate. However, the effect of diet on oral cancer is still a poorly recognized issue. The aim of this study was to assess the relationship between the risk of oral cancer and dietary ingredients with a particular emphasis on red meat and thermally processed meat. This study was conducted among patients with oral cancer in 2022 and 2023. The shortened standardized Food Frequency Questionnaire (FFQ) and a multivariate regression statistical analysis were used. The high consumption of red meat in general and thermally processed meat, especially smoked, fried, roasted and boiled, increases the risk of oral cavity cancer. Limiting the consumption of meat products and modifying the methods of preparing meat dishes may reduce exposure to carcinogenic compounds from the diet and thus reduce the risk of developing oral cancer. Full article

The heating process is a crucial step that can lead to the formation of several harmful chemical compounds in red meat such as heterocyclic aromatic amines, N-Nitrosamines, polycyclic aromatic hydrocarbons and acrylamide. Meat has high nutritional value, providing essential amino acids, bioactive compounds and several important micronutrients which can also be affected by heating processes. This review aims to provide an updated overview of the effects of different heating processes on both the safety and nutritional parameters of cooked red meat. The most-used heating processes practices were taken into consideration in order to develop a risk–benefit scenario for each type of heating process and red meat. Full article

This study aims to explore the effects of frying conditions on the formation of HAs and PAHs in crispy pork spareribs, a popular meat commodity sold on Taiwan’s market. Raw pork spareribs were marinated, coated with sweet potato powder, and fried in soybean oil and palm oil at 190 °C/6 min or 150 °C/12 min, followed by an analysis of HAs and PAHs via QuEChERS coupled with UPLC-MS/MS and GC-MS/MS, respectively. Both HAs and PAHs in pork spareribs during frying followed a temperature- and time-dependent rise. A total of 7 HAs (20.34–25.97 μg/kg) and 12 PAHs (67.69–85.10 μg/kg) were detected in pork spareribs fried in soybean oil and palm oil at 150 °C/12 min or 190 °C/6 min, with palm oil producing a higher level of total HAs and a lower level of total PAHs than soybean oil. The content changes of amino acid, reducing sugar, and creatinine played a vital role in affecting HA formation, while the degree of oil unsaturation and the contents of precursors including benzaldehyde, 2-cyclohexene-1-one, and trans,trans-2,4-decadienal showed a crucial role in affecting PAH formation. The principal component analysis revealed that HAs and PAHs were formed by different mechanisms, with the latter being more liable to formation in pork spareribs during frying, while the two-factorial analysis indicated that the interaction between oil type and frying condition was insignificant for HAs and PAHs generated in crispy pork spareribs. Both CcdP (22.67–32.78 μg/kg) and Pyr (16.70–22.36 μg/kg) dominated in PAH formation, while Harman (14.46–17.91 μg/kg) and Norharman (3.41–4.55 μg/kg) dominated in HA formation in crispy pork spareribs during frying. The outcome of this study forms a basis for learning both the variety and content of HAs and PAHs generated during the frying of pork spareribs and the optimum frying condition to minimize their formation. Full article

There has been continuous interest in developing novel activators that facilitate the functionalization of cellulosic materials. In this paper, we developed a strategy in which trisubstituted triazinium salts act as cellulose preactivators. As leaving groups, these triazinium salts utilize N-heterocycles (pyridine, imidazole, and nicotinic acid). Initially, we optimized the synthetic route for developing these novel cellulose preactivators (triazinium salts), whose structures were confirmed using NMR spectroscopy. The surface zeta potential of cellulose changed from a negative value to a positive one after preactivation due to the cationic nature of these preactivators. To enhance the scope of the study, we functionalized the cellulose-preactivated materials with a series of amine- or hydroxy-containing aliphatic and aromatic hydrocarbons, nucleophilic amino acids (cysteine), colorants (2-aminoanthraquinone and 2-amino-3-methyl-anthraquinone), and biopolymer (zein protein). The treated samples were analyzed using FTIR, time-gated Raman spectroscopy, and reflection spectroscopy, and the success of the functionalization process was validated. To widen the scope of such chemistries, we synthesized four reactive agents containing N-heterocyclic-based leaving groups (pyridine and nicotinic acid) and successfully functionalized cellulose with them in one step. The proposed single- and two-step functionalization approaches will provide opportunities for chemically linking various chemical compounds to cellulose for different applications. Full article