Inhibition of mutagenic PhIP formation by epigallocatechin gallate via scavenging of phenylacetaldehyde

Polyphenols as reactive carbonyl substances regulators: A comprehensive review of thermal processing hazards mitigation

Reactive carbonyl species (RCS) are a class of compounds with one or more C = O structures with highly reactive electrophilic properties. This comprehensive review delves into the multifaceted role of RCS in thermally processed foods, where they serve as both crucial intermediates in the development of food color and flavor, as well as precursors of potentially harmful compounds. By exploring the carbonyl pool concept, the impact of RCS equilibrium on the formation and reduction of hazardous substances such as acrylamide, hydroxymethylfurfural, advanced glycation end-products, and heterocyclic amines was elucidated. The review particularly emphasizes the regulatory effects of polyphenols on the carbonyl pool, highlighting their potential to reduce the levels of RCS and their associated hazards. Furthermore, the dual role of polyphenols in both mitigating and enhancing to the formation of RCS and their associated hazards was discussed. This review offers valuable insights into strategies for inhibiting RCS and their associated hazards.

A comprehensive review of structure-activity relationships and effect mechanisms of polyphenols on heterocyclic aromatic amines formation in thermal-processed food

Heterocyclic aromatic amines (HAAs) are potent carcinogenic substances mainly generated in thermal-processed food. Natural polyphenols have been widely used for inhibiting the formation of HAAs, whereas the effect of natural polyphenols on HAAs formation is complex and the mechanisms are far from being clearly elucidated. In order to clarify the comprehensive effect of polyphenols on HAAs, this review focused on the structure-activity relationships and effect mechanisms of polyphenols on the formation of HAAs. In addition, the effects of polyphenols on HAAs toxicity were also first reviewed from cell, gene, protein, and animal aspects. An overview of the effect of polyphenol structures such as parent ring and exocyclic group on the mitigation of HAAs was emphasized, aiming to provide some valuable information for understanding their effect mechanism. The HAAs formation is inhibited by natural polyphenols in a dose-dependent manner largely through eliminating free radicals and binding precursors and intermediates. The inhibitory effect was probably affected by the quantity and position of hydroxyl groups in the aromatic rings, and polyphenols with m-hydroxyl group in the aromatic ring had the stronger inhibitory effect. However, the presence of other substituents and excessive hydroxyl groups in natural polyphenols might mitigate the inhibitory effect and even promote the formation of HAAs. This review can provide theoretical reference for effectively controlling the formation of HAAs in thermal-processed food by natural polyphenols and reducing their harm to human health.

Using bioactive compounds to mitigate the formation of typical chemical contaminants generated during the thermal processing of different food matrices

With rising consumer awareness of health and wellness, the demand for enhanced food safety is rapidly increasing. The generation of chemical contaminants during the thermal processing of food materials, including polycyclic aromatic hydrocarbons, heterocyclic aromatic amines, and acrylamide happens every day in every kitchen all around the world. Unlike extraneous chemical contaminants (e.g., pesticides, herbicides, and chemical fertilizers), these endogenic chemical contaminants occur during the cooking process and cannot be removed before consumption. Therefore, much effort has been invested in searching for ways to reduce such thermally induced chemical contaminants. Recently, the addition of bioactive compounds has been found to be effective and promising. However, no systematic review of this practical science has been made yet. This review aims to summarize the latest applications of bioactive compounds for the control of chemical contaminants during food thermal processing. The underlying generation mechanisms and the toxic effects of these chemical contaminants are discussed in depth to reveal how and why they are suppressed by the addition of certain bioactive ingredients. Examples of specific bioactive compounds, such as phenolic compounds and organic acids, as well as their application scenarios, are outlined. In the end, outlooks and expectations for future development are provided based on a comprehensive summary and reflection of references.

Effects of seasoning addition and cooking conditions on the formation of free and protein-bound heterocyclic amines and advanced glycation end products in braised lamb

The accumulation of heterocyclic amines (HAs) and advanced glycation end products (AGEs) in thermally processed meats has been arising safety concerns. The effects of cooking conditions and seasoning addition on the formation of HAs and AGEs in Chinese traditional braised lamb were investigated by UPLC-MS/MS analysis. Soy sauce significantly increased the formation of HAs and AGEs, among which light soy sauce had the greatest promoting effect (69.45-15300.62 %). Conversely, spices inhibited HAs and AGEs formation, the inhibition rate of free HAs and AGEs reached 22.06-34.72 % when using 70 % ethanol extract. Hot blanching treatment and adding soy sauce and spices at a later stage could significantly suppress HAs and AGEs production. Flavonoids, including galangin, hesperidin, narirutin, etc., were identified as key effectors in spices. These findings help to promote awareness of the formation of HAs and AGEs in braised lamb and provide valuable insights for optimizing processing techniques to minimize their production.

The evaluation of catechins reducing heterocyclic aromatic amine formation: Structure-activity relationship and mechanism speculation

The favorable inhibitory effect of tea polyphenols on heterocyclic aromatic amines (HAAs) has been confirmed in many past studies. The objective of this study was to investigate the structure-activity relationship of catechins that act as inhibitors of HAA formation in chemical models. Two kinds of quantitative structure-activity relationship models for catechin-inhibiting-HAA were established. We chose two kinds of HAAs including 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) and 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx), and five catechins including epigallocatechin gallate (EGCG), epicatechin gallate (ECG), epigallocatechin (EGC), epicatechin (EC), and catechin (C). The inhibitory effect of five catechins were in the following order: EGCG > ECG > EGC > C > EC. Thereinto, EGCG and ECG showed dramatically better inhibition on the formation of PhIP and MeIQx, especially EGCG. Further, the mechanisms of catechin-inhibiting-HAA were speculated by correlation analysis. The free radical-scavenging ability was predicted to be the most relevant to the inhibitory effect of ECG, EGC, EC and C on HAAs. Differently, the phenylacetaldehyde-trapping ability might be the more important mechanism of EGCG inhibiting PhIP in chemical model system. This study may bring a broader idea for controlling the formation of HAAs according to the structure of catechins.

Emerging challenges and efficacy of polyphenols-proteins interaction in maintaining the meat safety during thermal processing

Polyphenols are well documented against the inhibition of foodborne toxicants in meat, such as heterocyclic amines, Maillard's reaction products, and protein oxidation, by means of their radical scavenging ability, metal chelation, antioxidant properties, and ability to form protein-polyphenol complexes (PPCs). However, their thermal stability, low polarity, degree of dispersion and polymerization, reactivity, solubility, gel forming properties, low bioaccessibility index during digestion, and negative impact on sensory properties are all questionable at oil-in-water interface. This paper aims to review the possibility and efficacy of polyphenols against the inhibition of mutagenic and carcinogenic oxidative products in thermally processed meat. The major findings revealed that structure of polyphenols, for example, molecular size, no of substituted carbons, hydroxyl groups and their position, sufficient size to occupy reacting sites, and ability to form quinones, are the main technical points that affect their reactivity in order to form PPCs. Following a discussion of the future of polyphenols in meat-based products, this paper offers intervention strategies, such as the combined use of food additives and hydrocolloids, processing techniques, precursors, and structure-binding relationships, which can react synergistically with polyphenols to improve their effectiveness during intensive thermal processing. This comprehensive review serves as a valuable source for food scientists, providing insights and recommendations for the appropriate use of polyphenols in meat-based products.

Effect of Immersion Time of Chicken Breast in Potato Starch Coating Containing Lysine on PhIP Levels

This study investigated the effect of immersion time of chicken breasts in potato starch (PS) coating containing amino acids (AAs) on the formation of 2-amino-1-methyl-6-phenylimidazo [4,5-b] pyridine (PhIP) and to evaluate a possible mechanism to inhibit the formation of PhIP in chicken breasts during frying. The chicken breasts with standardized dimensions were dipped in the potato starch (PS) coating solution containing 0.25% w/v lysine (Lys) for different times (15 min, 30 min, 1 h, 3 h, and 6 h). After drying the coating on the chickens, samples were fried at 195 °C for 7.5 min on each side. Results showed that the immersion time does not significantly decrease (p < 0.05) the PhIP level, suggesting that 15 min immersion time is enough for PhIP reduction compared to the control chicken samples (without coating). Phenylacetaldehyde (PheAce) was increased in chicken breast coated with PS-0.25% Lys after frying, suggesting that there should be another pathway to prevent the formation of PhIP by the addition of PS-0.25% Lys. Volatile compound analysis also confirmed this and showed increases in many aroma compounds in the coated chicken. Moreover, no significant differences (p < 0.05) were shown between the cooking loss percentage, color parameters, texture profile, and tenderness of chicken with the PS-0.25% coating and chicken without coating.

Flavonoids mitigation of typical food thermal processing contaminants: Potential mechanisms and analytical strategies

Due to unique chemical structure, flavonoids are secondary metabolites with numerous biological activities. Thermal processing of food usually produces some chemical contaminants, which cause an adverse effect on food quality and nutrition. Therefore, it is vital to reduce these contaminants in food processing. In this study, current researches around the inhibitory effect of flavonoids on acrylamide, furans, α-dicarbonyl compounds and heterocyclic amines (HAs) were summarized. It has been shown that flavonoids inhibited the formation of these contaminants to varying degrees in chemical or food models. The mechanism was mainly associated with natural chemical structure and partly with antioxidant activity of flavonoids. Additionally, methods and tools of analyzing interactions between flavonoids and contaminants were discussed. In summary, this review demonstrated potential mechanisms and analytical strategies of flavonoids in food thermal processing, providing new insight of flavonoids applying on the food engineering.

Interaction between Chinese quince fruit proanthocyanidins and bovine serum albumin: Antioxidant activity, thermal stability and heterocyclic amine inhibition

Heterocyclic amines (HCAs) are carcinogenic and mutagenic substances produced in fried meat. Adding natural antioxidants (e.g., proanthocyanidins (PAs)) is a common method to reduce HCAs; however, the interaction between the PAs and protein can affect the inhibitory efficacy of PAs on the formation of HCAs. In this study, two PAs (F1 and F2) with different degrees of polymerization (DP) were extracted from Chinese quince fruits. These were combined with bovine serum albumin (BSA). The thermal stability, antioxidant capacity and HCAs inhibition of all four (F1, F2, F1-BSA, F2-BSA) were compared. The results showed that F1 and F2 interact with BSA to form complexes. Circular dichroism spectra indicate that complexes had fewer α-helices and more β-sheets, β-turns and random coils than BSA. Molecular docking studies indicated that hydrogen bonds and hydrophobic interactions are the forces holding the complexes together. The thermal stabilities of F1 and, particularly, F2 were stronger than those of F1-BSA and F2-BSA. Interestingly, F1-BSA and F2-BSA showed increased antioxidant activity with increasing temperature. F1-BSA's and F2-BSA's HCAs inhibition was stronger than F1 and F2, reaching 72.06 % and 76.3 %, respectively, for norharman. This suggests that PAs can be used as natural antioxidants for reducing the HCAs in fried foods.

Caffeic Acid and Diseases-Mechanisms of Action

Caffeic acid belongs to the polyphenol compounds we consume daily, often in the form of coffee. Even though it is less explored than caffeic acid phenethyl ester, it still has many positive effects on human health. Caffeic acid can affect cancer, diabetes, atherosclerosis, Alzheimer's disease, or bacterial and viral infections. This review focuses on the molecular mechanisms of how caffeic acid achieves its effects.

Synergistic Inhibitory Effects of Selected Amino Acids on the Formation of 2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) in both Benzaldehyde- and Phenylacetaldehyde-Creatinine Model Systems

Although various inhibitors have been employed to react with phenylacetaldehyde to form adducts and thus interrupt the formation of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), high concentrations of PhIP remain in the final system. It remains unknown whether other critical aldehyde or ketone intermediates are involved in the generation of PhIP, and scavenging these reactive carbonyls simultaneously may achieve higher inhibitory efficiency of PhIP. In this study, reactive carbonyls in a glucose/creatinine/phenylalanine model system were first identified by gas chromatography-mass spectrometry (GC-MS), and then the single and synergistic effects of nonprecursor amino acids (cysteine, methionine, proline, histidine, arginine, and leucine) on scavenging reactive carbonyls were investigated to find out promising combination partners. The obtained results showed that the concentrations of benzaldehyde and phenylacetaldehyde in the glucose/creatinine/phenylalanine model system reached 0.49 ± 0.01 and 6.22 ± 0.21 μg/mL, respectively. Heating these carbonyl compounds in the presence of creatinine resulted in the quantity of PhIP produced increasing linearly with the added quantity of benzaldehyde (r = 0.9733, P = 0.0002) and phenylacetaldehyde (r = 0.9746, P = 0.0002), indicating that both compounds are key intermediates for PhIP generation. Among the investigated amino acids, histidine produced the maximum inhibition of PhIP formation (78-99%) in the benzaldehyde/creatinine model system, and proline produced the maximum inhibition of PhIP formation (13-97%) in the phenylacetaldehyde/creatinine model system, where both compounds decreased PhIP formation in a dose-dependent manner. Histidine in combination with proline enhanced the inhibitory effect against PhIP formation at a low addition level, where the highest inhibitory efficiency was obtained using a 1:3 mass ratio of histidine to proline (2 mg/mL in total), reducing PhIP formation by 96%. These findings suggest that histidine-proline combinations can scavenge benzaldehyde and phenylacetaldehyde simultaneously, enhancing the suppression of PhIP formation.

Mitigative capacity of Kaempferia galanga L. and kaempferol on heterocyclic amines and advanced glycation end products in roasted beef patties and related mechanistic analysis by density functional theory

The capacity of Kaempferia galanga L. (KG) and kaempferol to mitigate the formation of free and bound heterocyclic amines (HAs) and advanced glycation end products (AGEs) in roast beef patties was explored. Electron paramagnetic resonance (EPR) and density functional theory (DFT) were used to reveal the possible mechanisms involved in quenching the free radicals. KG (0.5%, 1.0%, 1.5%) and kaempferol (0.005%, 0.010%, 0.015%) reduced HAs and AGEs in a dose-dependent manner. Alkyl free radical, HOO·, and ¹O₂ were critical to the formation of HAs, and ¹O₂ was pivotal to AGEs. They were quenched by KG and kaempferol in a dose-dependent manner. DFT indicated that the 3-OH group of kaempferol was most pivotal and quenched the HOO· mainly via H-atom transfer. The active carbonyl intermediates phenylacetaldehyde, glyoxal, and methylglyoxal can also be reduced by KG and kaempferol in a dose-dependent manner, which may be result from the quenching of free radicals.

Formation of Carcinogens in Processed Meat and Its Measurement with the Usage of Artificial Digestion—A Review

Meat is a rich source of various nutrients. However, it needs processing before consumption, what in turn generates formation of carcinogenic compounds, i.a., polycyclic aromatic hydrocarbons (PAH), nitrosamines (NOCs), and the most mutagenic heterocyclic aromatic amines (HAAs). It was widely found that many factors affect the content of carcinogens in processed meat. However, it has recently been discovered that after digestion free HAAs are released, which are not detectable before enzymatic treatment. It was established that the highest percentage of carcinogens is released in the small intestine and that its amount can be increased up to 6.6-fold. The change in free HAAs content in analyzed samples was dependent on many factors such as meat type, doneness, particle size of meat, and the enzyme concentration used for digestion. In turn, introduction of bacteria naturally occurring in the human digestive tract into the model significantly decreases total amount of HAAs. Contrary, the addition of food ingredients rich in polyphenols, fiber, and water (pepper powder, onions, apples) increases free HAAs’ release up to 56.06%. Results suggests that in vitro digestion should be an integral step of sample preparation. Artificial digestion introduced before chromatographic analysis will allow to estimate accurately the content of carcinogens in processed meat.

The inhibitory effects of yellow mustard (Brassica juncea) and its characteristic pungent ingredient allyl isothiocyanate (AITC) on PhIP formation: Focused on the inhibitory pathways of AITC

The effects of yellow mustard (Brassica juncea) and its characteristic component allyl isothiocyanate (AITC) on the formation of 2-amino-y1-methyl-6-phenylimidazo[4,5-b] pyridine (PhIP) in roast beef patties and PhIP-producing model systems were investigated. The probable inhibitory pathways of AITC on PhIP formation were also investigated in the model systems. The results revealed that yellow mustard and AITC can reduce PhIP in roast beef patties up to 41.7% and 60.2%, respectively. The rate of inhibition of PhIP also reached 64.8% in the PhIP-producing model systems. Furthermore, AITC could react with creatinine and phenylalanine in the model system (reducing each by 15.0%%-23.7% and 31.4%-55.8%, respectively). AITC showed the great scavenging ability of free radical scavenging (up to 64.2%). AITC also reacted with the intermediate phenylacetaldehyde (16.9%-30.8%) and the final product PhIP (7.0%-24.6%). It is speculated that AITC can inhibit PhIP through competitive inhibition of precursors, blocking intermediate, free radical scavenging, and direct elimination of PhIP.

6-C-(E-Phenylethenyl)-naringenin, a Styryl Flavonoid, Inhibits Advanced Glycation End Product-Induced Inflammation by Upregulation of Nrf2

Styryl flavonoids can be formed during the thermal processing of meats and flavonoid-enriched foods, showing high potentials in the prevention of different diseases. In this study, the protective effects of several styryl flavonoids against advanced glycation end product (AGE)-induced inflammation were evaluated, with 6-C-(E-phenylethenyl)-naringenin (6-PN) showing the strongest activity among them. The results indicated that 6-PN significantly ameliorated AGE-induced damages in human umbilical vein endothelial cells, including inhibition of pro-inflammatory cytokines and reactive oxygen species (ROS) production through downregulating the protein levels of the receptor for AGEs (RAGE) and NADPH oxidase. Notably, 6-PN possessed a much higher bioavailability than its parental compound, naringenin. Furthermore, 6-PN also promoted the activation of the nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathway that was suppressed by AGEs, and the anti-inflammatory effects of 6-PN disappeared when the cells were treated with ML385, a Nrf2 inhibitor. Hence, 6-PN might inhibit AGE-induced inflammation by the RAGE/ROS/Nrf2 signaling pathway.

Mitigation of heterocyclic amines by phenolic compounds in allspice and perilla frutescens seed extract: The correlation between antioxidant capacities and mitigating activities

The effect of different levels of allspice and perilla frutescens seed extract (ASE and PSE) on the formation of heterocyclic amines (HCAs) in pan-fried chicken meat patties and the bioactive components found in ASE and PSE that contribute to the mitigation of HCAs were investigated in this study. DPPH radical scavenging activity was evaluated and the results indicated that APSE (ASE + PSE) showed the highest capacity to scavenge free radicals, and the most effective inhibition of HCAs formation. Furthermore, Single and mixed phenolic compounds exhibited a positive effect in scavenging free radicals and mitigating HCAs. The radical scavenging activity and HCAs inhibition effect of single phenolic compounds were highly correlated, whereas mixed phenolic compounds exhibited poor correlation. PCA analysis indicated that phenolic compounds had the maximum inhibitory effect on IQ, followed by Norharman and harman and the minimal effect on PhIP and 7,8-DiMeIQx.

Chitosan and flavonoid glycosides are promising combination partners for enhanced inhibition of heterocyclic amine formation in roast beef

The effects of different kinds of chitosan, oligomer (ChiO) and monomer (Gluco), and the combinations of polymer (Chi) or ChiO with flavonoid aglycones and glycosides against the formation of major HAs were investigated to find out potential combination partners for enhanced suppression of HA formation. Results in roast beef patties showed ChiO and Gluco significantly inhibited PhIP and MeIQx formation by 43-80% and 31-57%, respectively. Of which, ChiO was the most effective. In combinations with flavonoid glycosides (phloridzin, rutin and hesperidzin, respectively), Chi, but not ChiO, generated enhanced inhibitory effects. Further analysis showed Chi and phloridzin combined at a ratio of 1:1 was the most promising, especially in inhibiting PhIP, and the mechanism behind involved: 1) water retention by Chi, and 2) reduction of phenylalanine availability by phloridzin. These findings suggest that appropriate combination of Chi and flavonoid glycosides contributes to significant improvement in the safety of meat products.

Effects of the Deacetylation Degree of Chitosan on 2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) Formation in Chemical Models and Beef Patties

The effects of the deacetylation degree (DD) of chitosan on heterocyclic aromatic amine formation were investigated in chemical models and beef patties. The results in model systems showed that at lower addition levels (10 mg), chitosan with 85% DD showed the strongest inhibitory effect against 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) formation, while chitosan with a higher DD (95%) or a lower DD (72 and 50%) did not show any significantly inhibitory effect. Further mechanism study showed that chitosan addition reduced the content of Maillard reaction intermediates including phenylacetaldehyde and the aldol condensation product but increased the PhIP precursor creatinine residue in the chemical model, indicating that chitosan at least partially competed with creatinine to react with phenylacetaldehyde to inhibit PhIP formation. In roast beef patties, 0.15% (w/w) chitosan (85% DD) significantly reduced the formation of PhIP, MeIQx, 4,8-DiMeIQx, Harman, and Norharman by 56.21, 33.32, 31.35, 25.14, and 28.12%, respectively. Moreover, chitosan significantly inhibited the formation of aldehydes in roast beef patties, further confirming the above-mentioned inhibition mechanism. However, the addition of chitosan might promote fatty acid oxidation. In addition, chitosan addition below 0.15% (w/w) had no significant effect on the textural properties of the roast samples.

Heterocyclic amines in cooked meat products, shortcomings during evaluation, factors influencing formation, risk assessment and mitigation strategies

At this point in time, the evidence of a link between well-done meat intake and the incidence of cancer is stronger than it was 20 years ago. Several cohort and case-control studies have confirmed this evidence, and have shown a higher odd ratio and increased exposure to heterocyclic amines (HCAs) among those who frequently consume red meat. However, in most epidemiological studies, dietary assessment, combined with analytical data, is used to estimate the intake of HCAs, which has many inconsistencies. In addition, there is a lack of findings indicating a substantial correlation between various factors, like types of raw meat, types of meat products, and cooking methods that directly or indirectly influence the occurrence of cancer. Although numerous mitigation strategies have been developed to reduce HCAs levels in meat, there is still a high prevalence of carcinogenesis caused by HCAs in humans. The aim of this review is to summarise conflicting reports, address shortcomings and identify emerging trends of cutting-edge research related to HCAs.

Inhibitory effects of hyperoside and quercitrin from Zanthoxylum bungeanum Maxim. leaf on 2-amino-1-methyl-6-phenylimidazo [4,5-b]pyridine formation by trapping phenylacetaldehyde

2-amino-1-methyl-6-phenylimidazole[4,5-b]pyridine (PhIP) is one of the most abundant Heterocyclic amines (HAs) in meat products. Zanthoxylum bungeanum Maxim. leaf (ZML) extract has been shown to be rich in polyphenols, which are gaining increasing interest as efficient tools for inhibiting the formation of HAs. In the present work, the effects of ZML extract, major polyphenols, chlorogenic acid, hyperoside and quercitrin on the formation of PhIP in both roast beef patties and chemical model systems were investigated. UPLC-MS showed that ZML extract and those three polyphenols effectively inhibited PhIP formation. Additionally, GC-MS analysis showed that those three polyphenols significantly reduced the content of phenylacetaldehyde in the model systems, a key intermediate involved in PhIP formation. The subsequent UPLC-MS and TOF-MS/MS analysis found that hyperoside and quercitrin reacted with phenyacetaldehyde to form those four adducts, 8-C-(E-Phenylethenyl)hyperoside, 6-C-(E-Phenylethenyl)hyperoside, 8-C-(E-Phenylethenyl)quercitrin and 6-C-(E-Phenylethenyl)quercitrin, respectively. The results revealed that hyperoside and quercitrin could trap phenylacetaldehyde to form adducts, thereby, retarding the reaction of phenylacetaldehyde and creatinine, blocking the generation of PhIP.

Inhibitory Effects of Six Types of Tea on Aging and High-Fat Diet-Related Amyloid Formation Activities

Aging and lipid metabolism disorders promote the formation and accumulation of amyloid with β-sheet structure, closely related to cardiovascular disease, senile dementia, type 2 diabetes, and other senile degenerative diseases. In this study, five representative teas were selected from each of the six types of tea, and a total of 30 teas were selected to evaluate the inhibitory activities on the formation of aging-related amyloid in vitro. The results showed that the 30 teas had a significant inhibitory effect on the formation activity on aging-related amyloid at the protein level in vitro. Although the content of catechins is relatively low, black tea and dark tea still have significant antioxidant activity and inhibit the formation of amyloid. A high-fat diet established the model of lipid metabolism disorder in premature aging SAMP8 mice, and these mice were gavaged different tea water extracts. The results showed that different tea types have a significant inhibitory effect on the formation of β-amyloid and Aβ42 mediated by age-related lipid metabolism disorders, and the in vivo activity of fully fermented teas was better than that of green tea. The action mechanism was related to antioxidation, anti-inflammatory, and improving lipid metabolism.

Effect of basil use in meatball production on heterocyclic aromatic amine formation

Herein, the effects of basil usage in meatball production on various quality criteria and heterocyclic aromatic amine (HAA) formation were investigated. The use of basil at every rate caused a significant reduction in TBARS value compared to control group. Cooking caused an increase in pH and TBARS values. IQx, IQ, AαC and MeAαC compounds could not be detected, while various amounts of MeIQx, MeIQ, 7,8-DiMeIQx, 4,8-DiMeIQx and PhIP were determined in the samples. Total HAA contents were determined up to 1.61 ng g^-1 and increasing of cooking temperature increased total HAA content, except for meatball with 1% basil. The reducing or enhancing effect of the use of basil in meatball production on the formation of HAA varied depending on the usage rate and cooking temperature. It was determined that even if 100 g of the meatballs containing 0.5% basil cooked at 250 °C whose total amount of HAA content was the highest, is eaten, the intake amount is far below 1 μg.

Formation of naphthoquinones and anthraquinones by carbonyl-hydroquinone/benzoquinone reactions: A potential route for the origin of 9,10-anthraquinone in tea

The reaction of 2-alkenals (crotonaldehyde and 2-pentenal) with hydroquinones (hydroquinone and tert-butylhydroquinone) and benzoquinones (benzoquinone, methylbenzoquinone, and methoxybenzoquinone) was studied as a potential route for the endogenous formation of naphthoquinones and anthraquinones in foods. Polycyclic quinones were produced at a low water activity, within a wide pH range, and in the presence of air. 9,10-Anthraquinone formation had an activation energy of 46.1 ± 0.1 kJ·mol^-1, and a reaction pathway for the formation of the different naphthoquinones and anthraquinones is proposed. These reactions also took place in tea, therefore suggesting that the common tea pollutant 9,10-anthraquinone is also a process-induced contaminant. In fact, when four commercial teas (from a total of eight studied teas) were heated at 60 °C for 72 h, they significantly (p < 0.05) increased the amount of this toxicant. Reduction of 9,10-anthraquinone formation in teas is suggested to be carried out by reducing/scavenging its precursors.

Inhibitory effect of selected hydrocolloids on 2-amino-1-methyl-6-phenylimidazo [4,5-b]pyridine (PhIP) formation in chemical models and beef patties

2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) is a mutagen and a rodent carcinogen mainly formed in thermally processed muscle foods. Hydrocolloids are widely used as thickeners, gelling agents and stabilizers to improve food quality in the food industry. In this study, the inhibitory effects of eight hydrocolloids on the formation of PhIP were investigated in both chemical models and beef patties. 1% (w/w) of carboxymethylcellulose V, κ-carrageenan, alginic acid, and pectin significantly reduced PhIP formation by 53 %, 54 %, 48 %, and 47 %, respectively in chemical models. In fried beef patties, κ-carrageenan appeared to be most capable of inhibiting PhIP formation among the eight tested hydrocolloids. 1% (w/w) of κ-carrageenan caused a decreased formation of PhIP by 90 %. 1% (w/w) of κ-carrageenan also significantly reduced the formation of other heterocyclic aromatic amines including MeIQx and 4,8-DiMeIQx by 64 % and 48 %, respectively in fried beef patties. Further mechanism study showed that κ-carrageenan addition decreased the PhIP precursor creatinine residue and reduced the content of Maillard reaction intermediates including phenylacetaldehyde and aldol condensation product in the chemical model. κ-Carrageenan may inhibit PhIP formation via trapping both creatinine and phenylacetaldehyde. The structures of adducts formed between κ-carrageenan and creatinine and κ-carrageenan and phenylacetaldehyde merits further study.

A novel potent inhibitor of 2-amino-1-methyl-6-phenylimidazo[4,5-b] pyridine (PhIP) formation from Chinese chive: Identification, inhibitory effect and action mechanism

Differential solvent extraction and phytochemical profiling of Chinse chive were employed to identify its principal PhIP-formation inhibitory constituents. Six compounds (mangiferin, isorhamnetin, luteolin, rosmarinic acid, 6-methylcoumarin, and cyanidin-3-glucoside) were further analyzed in a PhIP-producing chemical model to identify the dominant inhibitor. Its inhibitory mechanism was investigated by assessing the contribution of antioxidation and scavenging of key PhIP precursor/intermediate. No significant correlation was observed between PhIP inhibition rates and antioxidant activities. Further evaluation of the novel potent inhibitor mangiferin revealed a highly significant correlation between its dose-dependent inhibition of PhIP formation and phenylacetaldehyde scavenging. Finally, the proposed mechanism was corroborated through organic synthesis and structural elucidation of the mangiferin-phenylacetaldehyde adduct. This study has identified a potent novel inhibitor of the most abundant HA in heat-processed food and characterized its action mechanism. These findings may provide insight for future studies on mitigation of dietary exposure to toxic Maillard products by polyphenolic phytochemicals.

Mitigation of heterocyclic aromatic amines in cooked meat. Part I: Informed selection of antioxidants based on molecular modeling

This work aimed to develop a method permitting an informed choice of antioxidants to reduce carcinogenic heterocyclic aromatic amine (HAA) formation during proteinaceous food cooking. Therefore, a three-step approach was developed. First, the most promising antioxidants were selected using molecular modeling approaches. For this, analog design was used to highlight the most suitable antioxidants based on their diversification potential using bioisosteric replacement. Then, structure activity relationship studies allowed drawing the relevant properties for inhibiting HAA formation and explained partly the inhibitory activity. Secondly, the approved antioxidants were tested in ground beef patties to assess their inhibitory properties against HAA formation. Resveratrol was found to be the most efficient as it totally inhibited MeIQ and reduced MeIQx and PhIP formation by 40 and 70%, respectively. Finally, natural ingredients rich in these antioxidants were evaluated. Oregano was found to totally inhibit MeIQ formation and to reduce by half MeIQx and PhIP formation.

Chinese chive and Mongolian leek suppress heterocyclic amine formation and enhance nutritional profile of roasted cod

Heterocyclic amines (HAs) are potent mutagens, which can form DNA adducts in various human tissues. There is increasing evidence that mutagenic HA formation and nutrition loss can occur concurrently in fish during vigorous heat treatment. Our study investigated the effects of five Allium spp. (garlic, onion, welsh onion, Chinese chive, and Mongolian leek) on reducing HA formation and improving nutritional quality of roasted cod (Gadus morhua). The results showed that cod patties pretreated with powders of the selected Allium spp. had significantly (P < 0.05) lower levels of HAs (82-92%, except garlic, 49%) than the control. The contents of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) in the patties exhibited strong negative correlations with total antioxidant activity (-0.937), phenolic (-0.948), and lipophilic flavonoid (-0.933) contents, whereas the 2-amino-3,8 dimethylimidazo [4,5-f] quinoxaline (MeIQx) (made up only ∼0.7-3% of total HAs) contents exhibited significant positive correlations with these antioxidant parameters. In terms of nutrient composition change, Chinese chive and Mongolian leek were the most effective in preventing oxidative degradation of proteins and unsaturated fatty acids in roasted cod patties, which was translated into significantly higher contents of soluble proteins, essential amino acids, and polyunsaturated fatty acids. This has been the first report on the strong HA-formation inhibitory effect of Chinese chive and Mongolian leek. The dual beneficial functionality of these two Allium spp. may be utilized to reduce the intake of hazardous by-products while enhancing the nutritional and antioxidant properties of roasted cod and probably other protein-rich heat-processed foods.

The Inhibitory Effects of Heterotrigona Itama Honey Marinades on the Formation of Carcinogenic Heterocyclic Amines in Grilled Beef Satay

Heterocyclic amines (HCAs) are carcinogenic food toxicants formed in cooked meats, which may increase the risk of cancer development in humans. Therefore, in this study, the effect of stingless bee honey from different botanical origins on the formation of HCAs in grilled beef satay was investigated. HCAs concentration in grilled beef satay was determined by using high performance liquid chromatography (HPLC). In total, six of the most toxigenic HCAs representing aminoimidazo-azaarenes (AIAs) (MeIQx, 4,8-DiMeIQx, and PhIP) and amino carbolines (norharman, harman, and AαC) groups were identified in all the beef samples investigated. A significant reduction in HCAs was observed in grilled beef marinated in honey as compared to beef samples marinated in table sugar (control), in which the reduction of 95.14%, 88.45%, 85.65%, and 57.22% was observed in gelam, starfruit, acacia, and Apis honey marinades, respectively. According to the partial least squares regression (PLS) model, the inhibition of HCAs in grilled beef was shown to be significantly correlated to the antioxidant activity (IC50) of the honey samples. Therefore, the results of this study revealed that the addition of stingless bee honey could play an important role in reducing HCAs in grilled beef.

Structure characteristics of flavonoids for heterocyclic aromatic amines inhibition using quantitative structure-activity relationship modeling

The objective of this study was to investigate the structure characteristics of flavonoids that act as inhibitors for heterocyclic aromatic amines (HAAs) formation. Five quantitative structure-activity relationship models for predicting the inhibitory rates of HAAs (norharman, harman, PhIP, MeIQx, and 4,8-DiMeIQx) were established using selected chemometric parameters (R² : 0.591-0.920), and indicated that the hydrophobicity, hydroxyl groups, and topological structure of flavonoids played important roles in the inhibition of HAAs formation. The 5,7-dihydroxyls in meta-position of the A-ring and the 4'-hydroxyl in the B-ring of flavonoids were critical for the inhibitory effects of HAAs, whereas the introduction of 3-hydroxyl and 3-O-glucoside in the C-ring reduced the inhibitory effects. Catechin served as the most effective inhibitor of HAAs followed by luteolin and genistein. The study can bring us a broader idea for controlling the formation of HAAs according to the structure of flavonoids. PRACTICAL APPLICATIONS: Heterocyclic aromatic amines (HAAs) are a class of organic substances with carcinogenic and mutagenic effect formed during the heating process of meat products. The formation of HAAs can be inhibited by adding natural antioxidants such as flavonoids to the meat during pretreatment. This inhibition is influenced by the unique structure of flavonoids. Thus, there has been an increasing demand to exploit the effective HAAs inhibitors from flavonoids by structure characteristics. Our study showed that the inhibitory effect of flavonoids on the formation of HAAs was mainly depended on their hydrophobicity, hydroxyl groups, and topological structure using the multiple QSAR models. Thus, effective HAAs inhibitors can be explored from dietary flavonoids according their structure characteristics.

Preventive potential and mechanism of dietary polyphenols on the formation of heterocyclic aromatic amines

Thermal processing is the most important and popular domestic cooking method. More than 30 heterocyclic aromatic amines have been identified in cooked meat using various methods. This review highlights preventive potential and mechanism of dietary polyphenols on the formation of heterocyclic amines. Tea, coffee, fruits, vegetable, and spice extracts rich in polyphenols exerted significant inhibition against the formation of heterocyclic aromatic amines. Some polyphenols, such as naringenin and epigallocatechin 3‐O‐gallate, can actively participate into food chemistry reaction to trap Strecker aldehyde and lower the formation of heterocyclic aromatic amines. In addition, some polyphenols can lower the mutagenicity of heterocyclic aromatic amines. More specifically, polyphenols possessing two hydroxyl groups at the meta position of aromatic ring are the most efficient one, but the presence of carboxylic or alkyl groups as substituents in the aromatic ring slightly reduced the inhibitory effect.

Isorhamnetin and Hispidulin from Tamarix ramosissima Inhibit 2-Amino-1-Methyl-6-Phenylimidazo[4,5-b]Pyridine (PhIP) Formation by Trapping Phenylacetaldehyde as a Key Mechanism

Tamarix has been widely used as barbecue skewers to obtain a good taste and a unique flavor of roast lamb in China. Many flavonoids have been identified from Tamarix, which is an important strategy employed to reduce the formation of heterocyclic amines (HAs) in roast meat. Isorhamnetin, hispidulin, and cirsimaritin from Tamarix ramosissima bark extract (TRE) effectively inhibit the formation of 2-amino-1-methyl-6-phenylimidazo[4,5-b] pyridine (PhIP), the most abundant HAs in foods, both in roast lamb patties and in chemical models. According to the results of the GC-MS analysis, TRE and the three flavonoids significantly reduced the contents of phenylacetaldehyde, an important intermediate involved in PhIP formation at three levels. A subsequent ultra performance liquid chromatography-mass spectrometry (UPLC-MS) analysis revealed that these flavonoids trapped phenylacetaldehyde by forming interaction adducts. The formation of three postulated adducts, 8-C-(E-phenylethenyl)isorhamnetin, 6-C-(E-phenylethenyl)isorhamnetin and 8-C-(E-phenylethenyl)hispidulin, in the chemical models and roast lamb patties was further confirmed by a TOF-MS/MS analysis. Our results demonstrate that TRE and the corresponding flavonoids trap phenylacetaldehyde to form adducts and thus inhibit PhIP formation, suggesting their great potential beneficial effects on human health.

6-C-(E-Phenylethenyl)Naringenin Attenuates the Stemness of Hepatocellular Carcinoma Cells by Suppressing Wnt/β-Catenin Signaling

The effect of a novel semi-natural derivative of naringenin, 6-C-(E-phenylethenyl)naringenin (6-CEPN) on hepatocellular carcinoma (HCC) stemness was evaluated both in vitro and in vivo. 6-CEPN reduced HCC cell viability, inhibited sphere formation, cell migration and invasion, and blocked epithelial-mesenchymal transition. It was equally effective against NANOG+ cells sorted from cultured HCC cells that was accompanied by downregulation of stemness-associated transcription factors and attenuated HIF-1 activity. Furthermore, 6-CEPN significantly enhanced the sensitivity of HCC cells to therapeutic drugs, and inhibited HCC tumor growth and lung metastasis of HCC cells. 6-CEPN suppressed Wnt/β-catenin signaling by inducing β-catenin degradation and inhibiting its nuclear translocation. Upregulation of GSK3β appeared to be crucial for 6-CEPN's inhibitory activity in the signaling pathway. These findings indicate that 6-CEPN has a strong effect against liver cancer, which is mediated, at least in part, by suppressing the stemness of HCC cells through an action mechanism involving Wnt/β-catenin signaling.

Phytochemical-Rich Antioxidant Extracts of Vaccinium Vitis-idaea L. Leaves Inhibit the Formation of Toxic Maillard Reaction Products in Food Models

Thermal treatment of proteinaceous foods generates heat-induced Maillard reaction substances including toxic advanced glycation end products (AGEs) and heterocyclic amines (HAs). It is known that plant phenolic compounds may influence Maillard reaction. This study investigated the impact of lingonberry leaf extracts on the formation of N^ε -(carboxymethyl)lysine (CML) and N^ε -(2-furoylmethyl)-L-lysine (furosine) in milk model system and HAs in meat-protein and meat model systems. In addition, lingonberry leaf extracts obtained by different solvents were characterized by radical scavenging, Folin-Ciocalteu assays and ultrahigh pressure liquid chromatography quadruple-time-of flight mass spectrometry (UPLC-qTOF-MS). Water extract (WE) stronger suppressed CML than furosine formation in milk model system: CML levels were reduced by nearly 40%. Moreover, quinic acid and catechin, which were abundant in WE, were effective in inhibiting CML and furosine formation. WE and acetone extract (AE) at 10 mg/mL significantly inhibited HAs formation in both model systems. However, higher suppressing effect on HAs formation showed AE, which had lower antioxidant capacity and total phenolic content values than WE. WE contained higher amounts of hydroxycinnamic acids, proanthocyanidins and flavonols, while AE was richer in flavan-3-ols and arbutin derivatives. It indicates that the composition of phenolics might be a major factor for explaining different effect of extracts from the same plant on HAs formation. In general, the results suggest that lingonberry leaves is a promising source of phytochemicals for inhibiting toxic Maillard reaction products and enriching foods with plant bioactive compounds. PRACTICAL APPLICATION: The increased consumption in processed foods has been linked with the increased risks of various diseases, while thermal food processing is required to develop flavor, insure safety, and extend shelf life. Therefore, developing effective technological means for inhibiting the formation of heat-induced toxic substances is an important task. This study showed a potential of lingonberry leaf extracts containing health beneficial phytochemicals to suppress the formation of toxic Maillard reaction products during heating of milk and meat.

Green Tea Polyphenols Decrease Strecker Aldehydes and Bind to Proteins in Lactose-Hydrolyzed UHT Milk

The effect of epigallocatechin gallate enriched green tea extract (GTE) on flavor, Maillard reactions and protein modifications in lactose-hydrolyzed (LH) ultrahigh temperature (UHT) processed milk was examined during storage at 40 °C for up to 42 days. Addition of GTE inhibited the formation of Strecker aldehydes by up to 95% compared to control milk, and the effect was similar when GTE was added either before or after UHT treatment. Release of free amino acids, caused by proteolysis, during storage was also decreased in GTE-added milk either before or after UHT treatment compared to control milk. Binding of polyphenols to milk proteins was observed in both fresh and stored milk samples. The inhibition of Strecker aldehyde formation by GTE may be explained by two different mechanisms; inhibition of proteolysis during storage by GTE or binding of amino acids and proteins to the GTE polyphenols.

Role of α-Dicarbonyl Compounds in the Inhibition Effect of Reducing Sugars on the Formation of 2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine

The effect of reducing sugars on formation of PhIP in fried pork was investigated, and the underlying mechanisms were revealed by studying the reaction pathways between α-dicarbonyl compounds (α-DCs) and PhIP. The addition of reducing sugars (such as glucose) greatly reduced the amount of PhIP in fried pork from 15.5 ng/g to less than 1.0 ng/g. The amount of PhIP decreased significantly with an increasing level of added α-DCs in model systems. Similarly, the addition of methylglyoxal (MGO) decreased significantly the levels of phenylalanine (Phe) and creatinine (Crn) but increased significantly the level of phenylacetaldehyde (PEA). 2-Amino-1-methyl-5-(2-oxopropylidene)-imidazol-4-one and N-(1-methyl-4-oxoimidazolidin-2-ylidene) amino propionic acids were identified in MGO/Crn and MGO/Crn/Phe model systems and fried pork with glucose. These results revealed that the degradation products of reducing sugars-α-DCs-play an important role in inhibiting formation of PhIP by reacting with key precursors of PhIP and itself.

Control of Maillard Reactions in Foods: Strategies and Chemical Mechanisms

Maillard reactions lead to changes in food color, organoleptic properties, protein functionality, and protein digestibility. Numerous different strategies for controlling Maillard reactions in foods have been attempted during the past decades. In this paper, recent advances in strategies for controlling the Maillard reaction and subsequent downstream reaction products in food systems are critically reviewed. The underlying mechanisms at play are presented, strengths and weaknesses of each strategy are discussed, and reasonable reaction mechanisms are proposed to reinforce the evaluations. The review includes strategies involving addition of functional ingredients, such as plant polyphenols and vitamins, as well as enzymes. The resulting trapping or modification of Maillard targets, reactive intermediates, and advanced glycation endproducts (AGEs) are presented with their potential unwanted side effects. Finally, recent advances in processing for control of Maillard reactions are discussed.