Improved enrichment and analysis of heterocyclic aromatic amines in thermally processed foods by magnetic solid phase extraction combined with HPLC-MS/MS

Drying methods affect nutritional value, amino acids, bioactive compounds, and in vitro function of extract in mulberry leaves

Mulberry leaves (ML) are nutrient-rich and beneficial for food and feed. Our study evaluated five drying methods-sun drying (SD), air drying (AD), oven drying (OD), freeze drying (FD), and vacuum-microwave drying (MD) for preserving nutrients and bioactivity. In vitro models tested the bioactivities of ML extracts. Results showed that machine-based methods (OD, FD, and MD) were superior to natural processes (SD, AD) retaining nutrients and bioactivity. OD preserved amino acids effectively, FD and MD retained crude protein and fibers, and MD excelled in maintaining the total polyphenols, vitamin E, minerals, and bioactive compounds, enhancing the antioxidant capacity and beneficial effects on lipid metabolism, ROS scavenging, and anti-apoptotic in lipid-laden HepG2 cells. Overall, FD and MD are ideal for high-value products like food and pharmaceuticals, while OD is cost-effective for animal feed. SD and AD lead to significant nutrient loss and are not recommended unless cost is a major concern.

Magnetic cationic covalent organic framework for efficient enrichment and detection of phenolic endocrine disruptors in foodstuffs

Endocrine disrupting chemicals (EDCs) have received significant attention in the food field due to their potential health risks. Herein, we proposed a novel core-shell structure magnetic cationic covalent organic framework (EB-DHTA-iCOF@Fe3O4) designed for the efficient enrichment of trace-level EDCs in foodstuffs and analyzed using HPLC-MS/MS. Due to the phenolic EDCs structure possessing hydroxyl functional groups which become protonated under alkaline conditions, resulting in the formation of negatively charged anions. The EB-DHTA-iCOF@Fe3O4 positively charged surface can have a good enrichment effect on EDCs with phenolic structures through electrostatic interactions, π - π interactions, and hydrogen bonding. This unique combination of interactions enhances the iCOF ability to selectively capture and enrich phenolic EDCs from complex matrices, thereby improving the sensitivity and efficiency of their detection in analytical applications. Under optimal magnetic solid-phase extraction (MSPE) conditions, the method showed excellent linearity (5-250 μg kg-1, R2 ≥ 0.9993) and a low detection limit (0.03-1.2 μg kg-1) for phenolic EDCs, with recovery rates between 86.0 % and 106.8 % and a relative standard deviation under 5.8 %. The approach highlights the potential of the ionic covalent organic framework as an adsorbent for MSPE, offering a promising approach for the detection and analysis of trace-level EDCs in foodstuffs.

Extraction and analytical approaches for the determination of post-food processing major carcinogens: A comprehensive review towards healthier processed food

Different food processing methods, e.g. fermentation, grilling, frying, etc., to improve food sensory attributes or shelf-stability are typically employed in different cuisines worldwide. These methods may illicit in-situ health-hazardous chemicals via thermal or enzymatic-mediated processes or chemical interactions with food preservatives. This review provides a comparative overview of the occurrence, extraction, and determination of the major food carcinogens such as nitrosamines (NAs), biogenic amines (BAs), heterocyclic aromatic amines (HAAs), polycyclic aromatic hydrocarbons (PAHs), ethyl carbamate (EC), and malondialdehyde (MDA). Their carcinogenicity levels vary from group 1 (carcinogenic to humans) e.g. benzo[a]pyrene, group 2A (probably carcinogenic to humans) e.g. N-nitrosodiethylamine, group 2B (possibly carcinogenic to humans) e.g. chrysene or group 3 (non-classifiable as carcinogenic to humans) e.g. MDA. Chromatography-based methods are the most predominant techniques used for their analysis. LC-MS is widely used for both volatile/non-volatile NAs, HAAs, BAs, and EC, whereas GC-MS is applied more for volatile NAs, PAHs and MDA.

Facile synthesis of magnetic ionic covalent organic framework and dispersive magnetic solid phase extraction of aromatic amino acid oxidation products in thermally processed foods

Aromatic amino acid oxidation products (AAAOPs) are newly discovered risk substances of thermal processes. Due to its significant polarity and trace level in food matrices, there are no efficient pre-treatment methods available to enrich AAAOPs. Herein, we proposed a magnetic cationic covalent organic framework (Fe3O4@EB-iCOF) as an adsorbent for dispersive magnetic solid-phase extraction (DMSPE). Benefiting from the unique charged characteristics of Fe3O4@EB-iCOF, AAAOPs can be enriched through electrostatic interaction and π-π interactions. Under the optimal DMSPE conditions, the combined HPLC-MS/MS method demonstrated good linearity (R2 ≥ 0.990) and a low detection limit (0.11-7.5 μg·kg-1) for AAAOPs. In addition, the method was applied to real sample and obtained satisfactory recoveries (86.8 % ∼ 109.9 %). Especially, we applied this method to the detection of AAAOPs in meat samples and conducted a preliminarily study on its formation rules, which provides a reliable basis for assessing potential dietary risks.

An integrated multi-system to screen quality markers of blossom of Citrus aurantium L. var. amara Engl. via combining lipid-lowering and expectorant assays

The present research demonstrated that an integrated multi-system based on the assays of lipid-lowering and expectorant effects was used to screen quality markers of an edible and medical material-the blossom of Citrus aurantium L. var. amara Engl. (BCAVA)-and a portion of active constituents were quantified in multiple batches to provide scientific data to establish a quality standard for BCAVA. Mouse models were developed to evaluate the lipid-lowering and expectorant effects, facilitating the investigation of medicinal parts through different polar extractions of BCAVA. Subsequently, ultra-high-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry was utilized for the in vivo and in vitro identification of chemical profiles within the medicinal parts of BCAVA. This methodological approach led to the selection and quantification of several active compounds from 21 batches of BCAVA sourced from different geographical regions samples. Notably, the ethanol extract of BCAVA exhibited significant lipid-lowering and expectorant effects while 183 compounds were identified in vitro and 109 in vivo, respectively. Then, five key ingredients were quantified, and the quantitative data were subjected to statistical analysis to discriminate between samples from various geographical regions. Overall, the findings underscore the significance of an integrated, assay-based approach for the characterization and quality assessment of BCAVA.

The magnetic layered double hydroxide/zeolitic imidazolate framework-8 nanocomposite coupled with HPLC-MS/MS for the detection of heterocyclic aromatic amines in thermally processed meat

In this research, a novel magnetic nanocomposite (Fe3O4@Zn/Al-LABSA-LDH/ZIF-8) was synthesized using Fe3O4 as the magnetic core, layered double hydroxide (LDH) with linear alkylbenzene sulfonic acid (LABSA) intercalation and zeolitic imidazolate framework-8 (ZIF-8) as the shell. Benefiting from the intercalation of LABSA into LDH combined with ZIF-8, the multiple interactions, including π-π stacking, hydrogen bonding, and electrostatic interactions, conferred high selectivity and good extraction capability to the material towards heterocyclic aromatic amines (HAAs). Fe3O4@Zn/Al-LABSA-LDH@ZIF-8 was used as an adsorbent for magnetic solid-phase extraction (MSPE) to enrich HAAs in thermally processed meat samples, followed by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) detection. The method exhibited a low detection limit (0.021-0.221 ng/g), good linearity (R2 ≥ 0.9999), high precision (RSD < 7.2 %), and satisfactory sample recovery (89.7 % -107.5 %). This research provides a promising approach for developing novel adsorbents in sample preparation and improving analytical performance.

Recent Advances in Biological and Technological Research of Fresh Fruit and Vegetable

Fresh fruit and vegetables are sources of vitamins, minerals, and dietary fiber; however, due to their short postharvest life, a large portion of the produce is lost [...].

FeMo2Ox(OH)y-based mineral hydrogels as a novel POD nanozyme for sensitive and selective detection of aromatic amines contaminants via a colorimetric sensor array

Developing convenient pathways to discriminate and identify multiple aromatic amines (AAs) remains fascinating and critical. Here, a novel three-channel colorimetric sensor array based on FeMo2Ox(OH)y-based mineral (FM) hydrogels is successfully constructed to monitor AAs in tap water. Benefiting from the substantial oxygen vacancies (VO), FM nanozymes exhibit extraordinary peroxidase (POD)-like activities with Km of 0.133 mM and Vmax of 2.518 × 10-2 mM·s-1 toward 3,3',5,5'-tetramethylbenzidine (TMB), which are much better than horseradish peroxidase and most of POD mimics. This reveals that doping Cu and Co into FM (FM-Cu and FM-Co) can change POD activity. Based on various POD activities, TMB and H2O2 are used to generate fingerprint colorimetry signals from the colorimetry sensor array. The analytes can accurately discriminate through linear discriminant analysis, with a detection limit as low as 2.12 × 10-2-0.14 μM. The sensor array can effectively identify and discriminate AA contaminants and their mixtures and has performed well in real sample tests.

β-Carbolines norharman and harman change neurobehavior causing neurological damage in Caenorhabditis elegans

β-Carbolines norharman and harman, belonging to the class of heterocyclic aromatic amines (HAAs), are typical hazardous substances produced during the thermal processing of food. Compared to other HAAs, there have been limited reports on the toxicity of β-carbolines. Nevertheless, the current studies are concerned with the neurotoxic effects of norharman and harman at high doses. It is still unknown whether the relatively low dose of β-carbolines in foods induces neurotoxicity and the mechanism of the toxicity. In this study, C. elegans was exposed to a series of gradients of norharman and harman (0, 0.05, 5, and 10 mg L-1). The survival rate and indicators of ethology (locomotor behaviors, foraging behavior, and chemotaxis ability) were assessed. The antioxidant system and the contents of neurotransmitters, as well as the activity of acetylcholinesterase (AChE), were evaluated. Additionally, the RNA-seq screening of differentially expressed genes (DEGs) revealed the potential molecular mechanisms of norharman- and harman-induced toxic effects. Our results indicated that the risk of long-term exposure to norharman and harman at low doses (food-related doses) should be emphasized. Moreover, β-carbolines might induce neurotoxicity by causing oxidative damage, regulating the content of neurotransmitters, and interfering with cytochrome P450 metabolism. This study would provide a toxicological basis for the neurotoxicity of β-carbolines and lay the foundation for the risk assessment of endogenous pollutants in food.

Dietary advanced glycation end products (dAGEs): An insight between modern diet and health

Advanced glycation end products (AGEs) are formed by a series of chemical reactions of amino acids, peptides, proteins, and ketones at normal temperature or heated non-enzymatic conditions. A large amount of AGEs derived from Maillard Reaction (MR) during the process of food heat-processing. After oral intake, dietary AGEs are converted into biological AGEs through digestion and absorption, and accumulated in almost all organs. The safety and health risk of dietary AGEs have attracted wide attention. Increasing evidence have shown that uptake of dietary AGEs is closely related to the occurrence of many chronic diseases, such as diabetes, chronic kidney disease, osteoporosis, and Alzheimer's disease. This review summarized the most updated information of production, bio-transport in vivo, detection technologies, and physiological toxicity of dietary AGEs, and also discussed approaches to inhibit dietary AGEs generation. Impressively, the future opportunities and challenges on the detection, toxicity, and inhibition of dietary AGEs are raised.

Simultaneous detection of heterocyclic aromatic amines and acrylamide in thermally processed foods by magnetic solid-phase extraction combined with HPLC-MS/MS based on cysteine-functionalized covalent organic frameworks

Acrylamide (AA) and heterocyclic aromatic amines (HAAs), as classic hazards produced during food thermal processing, have been widely concerned, but because of their polarity difference, it is very difficult to detect these contaminants simultaneously. Herein, novel cysteine (Cys)-functionalized magnetic covalent organic frameworks (Fe₃O₄@COF@Cys) were synthesized via a thiol-ene click strategy and then used as adsorbents for magnetic solid-phase extraction (MSPE). Benefiting from the hydrophobic properties of COFs and the modification of hydrophilic Cys, AA and HAAs could be enriched simultaneously. Then, a rapid and reliable method based on MSPE coupled with HPLC-MS/MS was developed for the simultaneous detection of AA and 5 HAAs in thermally processed foods. The proposed method showed good linearity (R² ≥ 0.9987) with satisfactory limits of detection (0.012-0.210 μg kg^-1) and recoveries (90.4-102.8%). Actual sample analysis showed that the levels of AA and HAAs in French fries were affected by frying time and temperature, water activity of samples, content and type of reaction precursors, and reuse of oils.

Recent advances and applications of magnetic covalent organic frameworks in food analysis

Recently, covalent organic frameworks (COFs) have been widely used to prepare magnetic adsorbents for food analysis due to their highly tunable porosity, large specific surface area, excellent chemical and thermal stability and large delocalised π-electron system. This review summarises the main types and preparation methods of magnetic COFs and their applications in food analysis for the detection of pesticide residues, veterinary drugs, endocrine-disrupting phenols and estrogens, plasticisers and other food contaminants. Furthermore, challenges and future outlook in the development of magnetic COFs for food analysis are discussed.

Development of a Modified QuEChERS Method Based on Magnetic Multi-Walled Carbon Nanotubes as a Clean-Up Adsorbent for the Analysis of Heterocyclic Aromatic Amines in Braised Sauce Beef

Heterocyclic aromatic amines (HAAs) generated during the cooking of meats cause adverse effects on human health. The purpose of the current research was to develop a modified QuEChERS (Quick, Easy, Cheap, Effective, Rugged, Safe) method using magnetic multi-walled carbon nanotubes (Fe3O4-MWCNTs) as clean-up adsorbents for the rapid determination of HAAs in braised sauce beef. The significant parameters in extraction and clean-up processes were screened and optimized. Under optimal conditions, the LODs ranged from 3.0 ng/g to 4.2 ng/g. The recoveries (78.5−103.2%) and relative standard deviations RSDs (<4.6%) of five HAAs were obtained. These are in accordance with the validation criteria (recovery in the range of 70−120% with RSD less than 20%). Compared with conventional clean-up adsorbents (PSA or C18), Fe3O4-MWCNTs displayed equivalent or better matrix removal efficiency, while making the pretreatment process easier and more time-saving through magnetic separation. Less usage of adsorbent makes the method possess another advantage of being lower in cost per sample. The method developed was successfully applied to analyze real samples collected from local deli counters, demonstrating Fe3O4-MWCNTs could be considered as an effective alternative adsorbent with great potential in the QuEChERS process.

Heterocyclic aromatic amines induce Neuro-2a cells cytotoxicity through oxidative stress-mediated mitochondria-dependent apoptotic signals

Heterocyclic aromatic amines (HAAs) are a class of hazardous compounds produced in food thermal processing. These compounds raise concerns because they have mutagenic and carcinogenic properties. However, the neurotoxicity of these compounds has received limited attention. Here, the toxic effects of three HAAs, i.e. 9H-pyrido[3,4-b]indole (Norharman), 1-methyl-9H-pyrido[3,4-b]indole (Harman), and 2-amino-3-methylimidazole[4,5-f]quinoline (IQ) were investigated in Neuro-2a cells model. The results showed that the survival rate of cells decreased in a dose-dependent manner and apoptosis occurred after exposure to the three HAAs for 24 h and 48 h. Their neurotoxicity was ranked as Harman > Norharman > IQ. Further, treatment of Harman, Norharman, or IQ at 50 and 100 μM for 48 h led to intracellular REDOX imbalance, which was manifested as increased ROS and malondialdehyde (MDA) levels, decreased GSH/GSSG ratio, and reduced SOD and CAT activities. Moreover, Norharman and Harman up-regulated the expression level of nuclear factor erythroid 2-related factor 2 (Nrf2), as well as the mRNA levels of Heme oxygenase-1 (HO-1) and NAD(P)H quinone oxidoredutase1 (NQO1), while IQ had no significant effect on the levels of Nrf2, HO-1, and NQO1. Additionally, Harman, Norharman, or IQ exposure significantly reduced mitochondrial membrane potential and intracellular ATP levels and up-regulated the levels of apoptosis-related genes and proteins. Collectively, our finding suggested that HAAs were neurotoxic, with mechanisms related to induction of oxidative stress and mitochondrial dysfunction.