Hydroxyl radical induced by lipid in Maillard reaction model system promotes diet-derived N(ε)-carboxymethyllysine formation

Effect of marinating with green tea extract on the safety and sensory profiles of oven-baked oyster

Baked oyster is a popular seafood dish around the world. The present study investigated the effect of various concentrations of a green-tea extract (GTE) marinade on the safety and sensory profiles of oysters baked for different durations. The results showed 10 g/L of GTE and 10-min baking time was the optimal combination, as supported by significantly attenuated lipid oxidation (35.29 %) and Nε-(carboxyethyl)lysine (CEL) content (48.51 %) without appreciable negative impact on the sensory or nutritional quality of the oysters. However, high concentrations of the marinade or prolonged baking promoted protein oxidation and Nε-(carboxymethyl)lysine (CML) formation likely through the pro-oxidative action of the GTE phytochemicals. Correlation analysis further revealed the main factors that affected CML, CEL, and fluorescent AGEs generation, respectively. These findings provide theoretical support for the protective effect and mechanism of GTE against quality deterioration of baked oysters and would help broaden the application of GTE in the food industry.

Dual functional roles of nutritional additives in nutritional fortification and safety of thermally processed food: Potential, limitations, and perspectives

The Maillard reaction (MR) has been established to be a paramount contributor to the characteristic sensory property of thermally processed food products. Meanwhile, MR also gives rise to myriads of harmful byproducts (HMPs) (e.g., advanced glycation end products (AGEs) and acrylamide). Nutritional additives have attracted increasing attention in recent years owing to their potential to simultaneously improve nutritional quality and attenuate HMP formation. In this manuscript, a brief overview of various nutritional additives (vitamins, minerals, fatty acids, amino acids, dietary fibers, and miscellaneous micronutrients) in heat-processed food is provided, followed by a summary of the formation mechanisms of AGEs and acrylamide highlighting the potential crosstalk between them. The main body of the manuscript is on the capability of nutritional additives to modulate AGE and acrylamide formation besides their traditional roles as nutritional enhancers. Finally, limitations/concerns associated with their use to attenuate dietary exposure to HMPs and future perspectives are discussed. Literature data support that through careful control of the addition levels, certain nutritional additives possess promising potential for simultaneous improvement of nutritional value and reduction of AGE and acrylamide content via multiple action mechanisms. Nonetheless, there are some major concerns that may limit their wide applications for achieving such dual functions, including influence on sensory properties of food products, potential overestimation of nutrition enhancement, and introduction of hazardous alternative reaction products or derivatives. These could be overcome through comprehensive assay of dose-response relationships and systematic evaluation of the diverse combinations from the same and/or different categories of nutritional additives to establish synergistic mixtures.

Effect of edible oil type on the formation of protein-bound Nε-(carboxymethyl)lysine in roasted pork patties

Protein-bound Nε-(carboxymethyl)lysine (CML), an advanced glycation end product within meat products, poses a potential health risk to humans. The objective of this study was to explore the impact of various edible oils on the formation of protein-bound CML in roasted pork patties. Eleven commercially edible oils including lard oil, corn oil, palm oil, olive oil, flaxseed oil, blended oil, camellia oil, walnut oil, soybean oil, peanut oil, and colza oil were added to pork tenderloin mince, respectively, at a proportion of 4 % to prepare raw pork patties. The protein-bound CML contents in the pork patties were determined by HPLC-MS/MS before and after roasting at 200 °C for 20 min. The results indicated that walnut oil, flaxseed oil, colza oil, olive oil, lard oil, corn oil, blended oil, and palm oil significantly reduced the accumulation of protein-bound CML in pork patties, of which the inhibition rate was in the 24.43 %-37.96 % range. Moreover, the addition of edible oil contributed to a marginal reduction in the loss of lysine. Meanwhile, glyoxal contents in pork patties were reduced by 16.72 %-43.21 % after roasting. Other than blend oil, all the other edible oils restrained protein oxidation in pork patties to varying degrees (between 20.16 % and 61.26 %). In addition, camellia oil, walnut oil, and flaxseed oil increased TBARS values of pork patties by 2.2-8.6 times when compared to the CON group. After analyzing the fatty acid compositions of eleven edible oils, five main fatty acids (palmitic acid, stearic acid, oleic acid, linoleic acid, and linolenic acid) were selected to establish Myofibrillar protein-Glucose-fatty acids systems to simulate the roasting process. The results showed that palmitic acid, oleic acid, linoleic acid, and linolenic acid obviously mitigated the formation of myofibrillar protein-bound CML, exhibiting suppression rates ranging from 10.38 % to 40.32 %. In conclusion, the addition of specific edible oil may curb protein-bound CML production in roasted pork patty by restraining protein or lipid oxidation, reducing lysine loss, and suppressing glyoxal production, which may be attributed to the fatty acid compositions of edible oils. This finding provides valuable guidance for the selection of healthy roasting oils in the thermal processing of meat products.

Effect of milk fat and its main fatty acids on oxidation and glycation level of milk

Milk is a highly nutritional food rich in protein and fat that is prone to deterioration by oxidation and glycation reactions at storage and processing. In this study, glycation products and lipid oxidation products contents in skim milk, whole milk, and milk fat simulation groups were determined to evaluate the effect of milk fat components on glycation at 120 °C for 60 min. The increase rate of carbonyl compound, main advanced glycation end products (AGEs) levels, and glycation sites number of α-casein and β-casein are higher in whole milk than that in skim milk, indicating that milk fat promoted protein glycation significantly. In milk fat simulation groups, oleic acid and linoleic acid (LA) were added to milk fat in skim milk proportionally, promoting the formation of glycation products; however, palmitic acid had no such effect. LA exhibited strong promotion on AGEs formation. Lipid oxidation radicals, protein carbonyl amine condensation, and carbonyl compound formation were critical factors for milk glycation, according to OPLS-DA results. Therefore, radicals of fat oxidation are speculated to trigger the early glycation, and carbonyl compounds of fat oxidation act as important intermediates of glycation, fat type, form, and its degradation rate, thus play essential roles in milk glycation.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s13197-022-05658-z.

Advanced Glycation End Products and Nitrosamines in Sausages Influenced by Processing Parameters, Food Additives and Fat during Thermal Processing

Advanced glycation end products (AGEs) and nitrosamines (NAs) in sausage are associated with pathogenic and carcinogenic risks. However, the multiple reaction parameters affecting the production of AGEs and NAs during sausage processing remain unclear. This experiment evaluated the effects of processing parameters, food additives and fat ratios on the formation of AGEs and NAs in sausages. The results showed a 2-3-fold increase in N^ε-(carboxymethyl)lysine (CML) and N^ε-(carboxyethyl)lysine (CEL) when the sausage processing temperature was increased from 90 °C to 130 °C, and N-nitrosodimethylamine (NDEA) increased from 3.68 ng/g to 6.41 ng/g. The addition of salt inhibited the formation of AGEs and NAs, and the inhibitory ability of 2 g/100 g of salt was 63.6% for CML and 36.5% for N-nitrosodimethylamine (NDMA). The addition of 10 mg/kg nitrite to sausages reduced CML formation by 43.9%, however, nitrite had a significant contribution to the formation of NAs. The addition of fat only slightly contributed to the production of CML. In addition, the relationship between α-dicarbonyl compounds and the formation of AGEs was investigated by measuring the changes in α-dicarbonyl compounds in sausages. The results showed two trends of AGEs and α-dicarbonyl compounds: AGEs increased with the increase in α-dicarbonyl compounds and AGE level increased but α-dicarbonyl compound level decreased.

Effect of Baking Temperature and Time on Advanced Glycation End Products and Polycyclic Aromatic Hydrocarbons in Beef

ABSTRACT

Beef is an important red meat that contains essential nutrients for human growth and development. Baking is a popular beef cooking method. Temperature and time play key roles in the final quality of beef. How temperature and time affect the changes of nutrients and the formation of harmful products in beef is not clear. The purpose of this study was to measure the content of water, fat, protein, ash, nitrite, total volatile base nitrogen, advanced glycation end products (AGEs) and their precursors, and polycyclic aromatic hydrocarbons (PAHs) at different temperatures (150, 190, 230, 270, and 310°C) for 20 min and at 190°C for different times (10, 20, and 30 min), so as to discuss the effect of different temperatures and times on beef nutrients and harmful products. The results showed that the moisture content of beef decreased with increased baking temperature and time, resulting in the increase of the relative content of fat, protein, and ash. The content of total volatile base nitrogen increased continuously. Compared with the control group, the content of glyoxal in beef decreased, whereas the content of methylglyoxal, pentosidine, and fluorescent AGEs increased, indicating the continuous accumulation of AGEs in beef. A total of 13 PAHs were identified by gas chromatography-mass spectrometry. The concentrations of 13 PAHs in beef increased with increases in baking temperature and time. The concentrations of BkP and BaP, which are the most carcinogenic to humans, were 0.36 and 0.35 μg/kg in raw meat, respectively; these were increased by high temperature and long baking times. After beef was baked at 270 and 310°C for 20 min, the concentration of BkP increased to 9.49 and 5.66 μg/kg, respectively, and the concentration of BaP increased to 5.45 and 4.42 μg/kg, respectively. After baking at 190°C for 30 and 40 min, the concentration of BkP increased to 4.81 and 24.20 μg/kg, respectively, and the concentration of BaP increased to 3.85 and 17.79 μg/kg, respectively.

HIGHLIGHTS

How advanced are we on the consequences of oral exposure to food contaminants on the occurrence of chronic non communicable diseases?

The development of an individual during fetal life and childhood is characterized by rapid growth as well as gradual maturation of organs and systems. Beyond the nutritional intake in essential nutrients, food contaminants can permanently influence the way organs mature and function. These processes are called "programming" and play an essential role in the occurrence of non-communicable chronic diseases throughout the lifespan. Populations as pregnant women, fetuses and young children are vulnerable and particularly sensitive to food contaminants which can induce epigenetic modifications transmissible to future generations. Among these contaminants, pesticides are found in most food matrices exposing humans to cocktails of molecules through variable concentrations and duration of exposure. The Maillard reaction products (MRPs) represent other food contaminants resulting from heat treatment of food. Modern diet, rich in fats and sugars, is also rich in neoformed pathogenic compounds, Advanced Glycation End products (AGEs), the levels of which depend on the heat treatment of foods and eating habits and whose effects on health are controversial. In this review, we have chosen to present the current knowledge on the impacts of selected pesticides and MRPs, on the risk of developing during life non-communicable chronic diseases such as IBD, metabolic disorders or allergies. A large review of literature was performed via Pubmed, and the most appropriate studies were summarised.

The association of N ε-Carboxymethyllysine with polyunsaturated and saturated fatty acids in healthy individuals

Red blood cell (RBC) fatty acids status is used as a biomarker of dietary intake of fats however, there is still a paucity of evidence regarding individual fatty acids and modulation of endogenous advanced glycation end-product (AGE) levels. Due to membrane PUFA being a well-known target for peroxidation, we hypothesized that cellular PUFAs are positively associated with circulatory N ε-carboxymethyllysine (CML) that is also influenced by glyoxal (GO) levels in healthy cohorts. To test this, we investigated the association between RBC fatty acids and circulatory AGEs biomarkers in healthy individuals. The results showed a negative association between saturated fatty acids (SFA) and CML and stepwise multivariate regression analysis indicated stearic acid was negatively associated with CML levels (β = -0.200, p=0.008) after adjusting for age, BMI, and gender. In addition, stearic acid: palmitic acid ratio was also negatively correlated with plasma concentrations of CML (rp= -0.191, p = 0.012) and glucose (rp= -0.288, p = 0.0001). Polyunsaturated fatty acids (PUFA) showed a positive association with CML levels particularly, docosapentaenoic acid, γ-Linolenic acid, arachidonic acid, and docosadienoic acid. However, these associations were not evident after the multiple regression analysis adjusted for age, BMI, and gender. A strong negative correlation (rp= -0.98, p< 0.0001) between total PUFA and total SFA was observed. Furthermore, the SFA:PUFA ratio was inversely correlated with CML (rp= -0.227, p< 0.003). Overall, this study indicates that different fats and their combinations may influence the formation of AGEs and that carefully controlled interventions are required to further test this hypothesis.

Effect of Freeze-Thaw Cycles on the Oxidation of Protein and Fat and Its Relationship with the Formation of Heterocyclic Aromatic Amines and Advanced Glycation End Products in Raw Meat

The aim of this research was to investigate the effect of the number of freeze–thaw cycles (0, 1, 3, 5, and 7) on porcine longissimus protein and lipid oxidation, as well as changes in heterocyclic aromatic amines (HAAs) and advanced glycation end products (AGEs) and their precursors. We analyzed the relationship among HAAs, AGEs, oxidation, and precursors and found the following results after seven freeze–thaw cycles. The HAAs, Norharman and Harman, were 20.33% and 16.67% higher, respectively. The AGEs, Nε-carboxyethyllysine (CEL) and Nε-carboxymethyllysine (CML), were 11.81% and 14.02% higher, respectively. Glucose, creatine, and creatinine were reduced by 33.92%, 5.93%, and 1.12%, respectively after seven freeze–thaw cycles. Norharman was significantly correlated with thiobarbituric acid reactive substances (TBARS; r² = 0.910) and glucose (r² = −0.914). Harman was significantly correlated to TBARS (r² = 0.951), carbonyl (r² = 0.990), and glucose (r² = −0.920). CEL was correlated to TBARS (r² = 0.992) and carbonyl (r² = 0.933). These changes suggest that oxidation and the Maillard reaction during freeze–thaw cycles promote HAA and AGE production in raw pork.

Electrochemical oxidative degradation of X-6G dye by boron-doped diamond anodes: Effect of operating parameters

Boron-doped diamond (BDD) is an excellent electrode material. As the anode in an electrochemical degradation tank, BDD has been receiving widespread attention for the treatment of azo dye wastewater. In this study, electrochemical oxidation (EO) was applied to electrolyze reactive brilliant yellow X-6G (X-6G) using BDD as the anode and Pt as the cathode. To balance the degradative effects and power consumption in the electrolysis process, the effects of a series of operating parameters, including current density, supporting electrolyte, initial pH, reaction temperature and initial dye concentration, were systematically studied. The oxidative process was analyzed by color removal rate, and the degree of mineralization was evaluated by TOC. The optimal experimental parameters were finally determined: 100 mA cm^-2, 0.05 M Na₂SO₄ electrolyte, pH 3.03, 60 °C, and an initial X-6G concentration of 100 mg L^-1. As a result, color completely disappeared after 0.75 h of electrolysis, and TOC was removed by 72.8% after 2 h of electrolysis. In conclusion, the EO of a BDD electrode as an anode can be a potent treatment method for X-6G synthetic wastewater.

Effect of unsaturated fatty acids on glycation product formation pathways (Ⅰ) the role of oleic acid

Research on advanced glycation end-products (AGEs) and their formation pathways in food processing has gradually increased because AGEs are associated with human health, especially with involvement of lipids. In this study, radicals and glycation products were detected via electron spin resonance (ESR) and ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) respectively. The correlation of important intermediates was used to explain the effect of oleic acid (OA) on the glycation products and pathways. The results indicated OA participation decreased the content of stable radicals and glycosyl compounds in Maillard Reaction (MR). The oxidation of OA produced active radicals, and electron transfer caused lysine to transform radical form. These radicals participated in the formation of fructosyllysine (FL) with glucose (Glc) via the MR. The participation of OA is acted as inhibiting the way of Glc autoxidation and promoting the glycation pathway from FL to 3-deoxyglucosone (3-DG) to fluorescent-AGEs. Orthogonal projection to latent structures discriminant analysis results indicated that 3-DG, D-glucosone and methylglyoxal are key products in discriminating the glycation reaction.

Lipids Promote Glycated Phospholipid Formation by Inducing Hydroxyl Radicals in a Maillard Reaction Model System

Food-derived glycated phospholipids is potentially hazardous to human health. However, there are few studies on the effects of lipids on the formation of glycated phospholipids. In this work, two model systems were established: (1) a model system including 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine (PE), glucose, and Fenton reagent and (2) a model system including PE, glucose, and five kind of vegetable oils. The contents of carboxymethyl-PE, carboxyethyl-PE, Amadori-PE, hydroxyl radical (OH•), glyoxal, and methylglyoxal were determined with high-performance liquid chromatography mass spectrometry. The results of the first model system showed that OH• oxidized glucose to produce glyoxal and methylglyoxal, which then reacted with PE to form carboxymethyl-PE and carboxyethyl-PE. OH• also oxidized Amadori-PE to form carboxymethyl-PE. The results of the second model system showed that vegetable oils with higher number of moles of carbon-carbon unsaturated double bond in vegetable oil per kilogram could produce more OH•, which promote the formation of carboxymethyl-PE and carboxyethyl-PE by oxidizing glucose and oil. We elucidated the effects of oils on the formation of glycated phospholipids in terms of OH• and intermediates. This work will contribute to better understanding the formation mechanism of glycated phospholipids with oil.

Effects of Catechins on Nε-(Carboxymethyl)lysine and Nε-(Carboxyethyl)lysine Formation in Green Tea and Model Systems

The effects of catechins on N^ε-(carboxymethyl)lysine (CML) and N^ε-(carboxyethyl)lysine (CEL) formation in green tea and related model systems were investigated in this study. Since the first step of green tea processing entails enzyme inactivation, the catechin content was maintained at a high level during processing. However, drying still had a great effect on CML and CEL formation, while other steps also contributed. Hence, model systems were developed to analyze the effects of catechins on CML and CEL formation. Catechins ((-)-epicatechin gallate, (-)-epigallocatechin, and (-)-epigallocatechin gallate) could inhibit CML formation in the model imitating the condition of green tea processing, though the inhibitory efficiency was reduced by transition metals. This suggested that catechins could inhibit CML formation in the real tea system, though the inhibitory efficiency may be reduced by tea components which promote its synthesis. However, CEL formation was not always inhibited by the tested catechins, though catechins could significantly decrease the content of methylglyoxal which is considered an important intermediate. Consequently, the main pathway of CEL formation may not be through methylglyoxal.

Effect of fatty acids and triglycerides on the formation of lysine-derived advanced glycation end-products in model systems exposed to frying temperature

Lysine-derived advanced glycation end-products (AGEs), including N^ε-carboxymethyllysine (CML), N^ε-carboxyethyllysine (CEL) and pyrraline, are prevalent in processed foods. The impact of lipids on AGE formation is still contentious and most of our current knowledge is based only on CML. Little is known about how lipids impact the formation of CEL and pyrraline, or their involvement in formation pathways. This study investigated the effect of lipids (fatty acids and triglycerides) on the formation of CML, CEL and pyrraline simultaneously in model systems subjected to frying temperature. The results showed the presence of the lipids promoted the formation of CML, CEL and pyrraline. The promotion effects on CML and CEL were not dependent on the unsaturation degree and addition level (50, 100 or 150 μmol) of lipid, while pyrraline formation depended on lipid type (fatty acids vs. triglycerides) and level. The concentration of CML and CEL was statistically correlated with the concentration of glyoxal (GO) and methylglyoxal (MGO), respectively. The pyrraline concentration was statistically correlated with fructoselysine concentration. These results suggested that lipids promote the formation of lysine-derived AGEs by impacting the generation of Amadori products and α-dicarbonyl compounds. This information may be useful for optimizing the formulation and processing conditions to create tastier and healthier foods.

Fatty acids and triglycerides impact lysine-derived AGE formation through modulating the formation of α-dicarbonyl compounds and Amadori products.

Effect of lipid oxidation on the formation of Nε-carboxymethyl-lysine and Nε-carboxyethyl-lysine in Chinese-style sausage during storage

This work aimed to investigate the effects of lipid oxidation on N^ε-carboxymethyllysine (CML) and N^ε-carboxyethyllysine (CEL) formation in three types of Chinese-style sausages during storage. Medium-high temperature dried sausage, naturally dehydrated sausage and smoke-dried sausage were prepared, and CML/CEL contents were measured. The result showed that CML and CEL levels increased with the increasing storage time, and an exponential correlation was found between thiobarbituric acid reactive substances (TBARs) and either CML (r² = 0.922) or CEL (r² = 0.921) in medium-high temperature dried sausages and smoke-dried sausage, which suggested that lipid oxidation could facilitate CML/CEL formation during storage. Furthermore, lipid oxidation and the Maillard reaction might have a synergistic effect on CML formation in Chinese-style sausages, as evidence by the results of model system during incubation. These findings indicated that lipid oxidation played a key role in CML/CEL formation during the storage of Chinese-style sausages.

Investigations on the reactions of α-dicarbonyl compounds with amino acids and proteins during in vitro digestion of biscuits

The reactions of dicarbonyl with amino acids and proteins duringin vitrodigestion were investigated in this study.

Effects of hydrophobic and ionic interactions on glycation of casein during Maillard reaction

This study aimed to investigate the effects of hydrophobic and ionic interactions on glycation of native and high-shear treated casein during heating. Casein-epicatechin and casein-calcium complexes were formed and glycated with glucose at different temperatures ranging from 70 to 150 °C in solution and dry states. Furosine, acid derivative of N-ε-fructoselysine (FL), and N-ε-carboxymethyl lysine (CML) were measured as indicators of early and advanced glycation, respectively. CML concentrations of casein-epicatechin and casein-calcium complexes heated in solution were significantly lower as compared to the control (p < 0.05). For instance, 182 ± 9.78 μg/g of CML formed in the control, while CML concentrations were 136 ± 10.7 and 101 ± 7.37 μg/g in casein-epicatechin and casein-calcium complexes, respectively, heated at 150 °C in the solution state. Treatment by high shear microfluidization further decreased the CML formed during heating at 70 °C in dry state. The results suggest that interactions with epicatechin molecule and calcium ion could be a useful strategy to limit advanced glycation of casein under certain conditions.

Antioxidant activities of saponins extracted from Radix Trichosanthis: an in vivo and in vitro evaluation

BACKGROUND

Radix Trichosanthis (RT), the dry root tuber of Trichosanthis kirilowii Maxim (Cucurbitaceae), is a traditional Chinese medicine. Although a wide range of saponin pharmacological properties has been identified, to our knowledge, this may be the first report to investigate the crude saponins from RT. The purpose of this study was to delineate the antioxidant activity both in vitro and in vivo by using ethyl acetate (EtOAc), n-butanol, and the mixture of n-butanol and EtOAc fractions.

METHODS

In vitro antioxidant activity was detected by using DPPH free radical, hydrogen peroxide scavenging, and reducing power assays. After pretreatment with different fractions saponins at 2 mg/kg/d and 3 mg/kg/d of crude drug, respectively, an established CCl4 induced acute cytotoxicity model was used to evaluate the in vivo antioxidant potential by detection of superoxide dismutase (SOD), malonaldehyde (MDA), lactate dehydrogenase (LDH), and total antioxidant capacity (T-AOC) levels.

RESULTS

The in vitro assay showed that the antioxidant activity of all the three fractions was promising. The reducing power of the EtOAc and the mixture of n-butanol and EtOAc extracts increased in a dose dependent manner. However, both the n-butanol and the mixture of n-butanol and EtOAc fractions in low dose exhibited in a time dependent manner with prolonged reaction time. As for hydrogen peroxide scavenging capability, the n-butanol fraction mainly demonstrated a time dependent manner, whereas EtOAc fraction showed a dose dependent manner. However, in case of in vivo assay, an increase of SOD and T-AOC and decrease of MDA and LDH levels were only observed in n-butanol (2 mg/kg/d of crude drug) extracts pretreatment group.

CONCLUSIONS

RT saponins in n-butanol fraction might be a potential antioxidant candidate, as CCl4-induced oxidative stress has been found to be alleviated, which may be associated with the time dependent manner of n-butanol saponins in a low dose. Further studies will be needed to investigate the active individual components in n-butanol extract, in vivo antioxidant activities and antioxidant mechanisms.