Formation of the comutagenic beta-carboline norharman in a simple tryptophan-containing model system at low temperature (40 degrees C-80 degrees C)

The Effects of Volatile Organic Compounds (VOCs) on the Formation of Heterocyclic Amines (HAs) in Meat Patties, under Different Smoking Temperatures and Durations

In this study, UPLC-MS/MS was used to study the effects of smoking duration and temperature on the formation of heterocyclic amines (HAs) in smoke-processed meat patties. Four kinds of free HAs—including F-7,8-DiMeIQx; F-MeAαC; F-Harman and F-Norharman—and six kinds of protein-bound HAs—including B-AαC; B-7,8-DiMeIQx; B-Glu-p-1; B-MeAαC; B-Harman and B-Norharman—were detected and quantified. Among the free HAs, we observed a 23-fold content increase (p < 0.05), from 0−4 h (at 0 h and 4 h they were 4.24 ng·g−1 and 98.33 ng·g−1, respectively), and the content of the free HAs decreased to 78.80 ng·g−1, at 5 h. At the same time, the free HAs content increased from 53.52 ng·g−1, at 50 °C, to 127.16 ng·g−1, at 60 °C, and then decreased continuously. The content of the free HAs was the highest at 60 °C. For the protein-bound HAs, their content was found to generally decrease with the increase in smoking duration and temperature. However, at 5 h, the content of protein-bound HAs slightly increased to 984.2 ng·g−1. Meanwhile, at 90 °C, it increased to 1643.53 ng·g−1. Additionally, a total of 16 volatile organic compounds (VOCs) were found in all of the meat samples, of which 10 VOCs (one acid, three aldehydes and seven phenols) were significantly related to the formation of free HAs. These findings showed that all the different types of HAs were produced under low-temperature processing, which provided scientific insights into the potential generation of HAs during meat smoking processes and could be used as a reference to minimize the risks of cancer related to the consumption of smoked meat products.

Determination of heterocyclic amines in braised sauce beef and the effects of different cooking conditions on the formation of heterocyclic amines

BACKGROUND

Cooked meat is a good source of high-quality protein. However, during long-term cooking of meat, radical-induced lipid and protein oxidation may lead to the formation of poisonous compounds, such as heterocyclic amines (HAs). This work investigated a testing method for HAs and it describes that cooking temperature, cooking time and repeated cooking times have influences on the overall quality of braised sauce beef and the effect of HAs formation.

RESULTS

The improved method has a good separation effect on nine kinds of HAs. The average recovery of HAs at two spiked levels is between 51.70% and 88.25% (n = 6). The detection limit is 0.025-0.060 ng g^-1 , and the limit of quantitation is 0.070-0.160 ng g^-1 . Only harman and norharman were detected in samples. Cooking time and cooking temperature will affect the quality and HA content of samples. When the braised sauce beef soup was cooked 20 times, the HA content was the highest - as high as 21.43 ng g^-1 . The more times the beef was cooked repeatedly, the higher was the HA content. Under different cooking conditions, glucose has a significant effect on the formation of β-carboline.

CONCLUSION

We have established a detection method for HAs with good repeatability and accuracy. HAs were more easily formed in braised sauce beef by high temperature, long heating and repeated brine cooking. © 2021 Society of Chemical Industry.

Reactivity and degradation products of tryptophan in solution and proteins

Tryptophan is one of the essential mammalian amino acids and is thus a required component in human nutrition, animal feeds, and cell culture media. However, this aromatic amino acid is highly susceptible to oxidation and is known to degrade into multiple products during manufacturing, storage, and processing. Many physical and chemical processes contribute to the degradation of this compound, primarily via oxidation or cleavage of the highly reactive indole ring. The central contributing factors are reactive oxygen species, such as singlet oxygen, hydrogen peroxide, and hydroxyl radicals; light and photosensitizers; metals; and heat. In a multi-component mixture, tryptophan also commonly reacts with carbonyl-containing compounds, leading to a wide variety of products. The purpose of this review is to summarize the current state of knowledge regarding the degradation and interaction products of tryptophan in complex liquid solutions and in proteins. For the purposes of context, a brief summary of the key pathways in tryptophan metabolism will be included, along with common methods and issues in tryptophan manufacturing. The review will focus on the conditions that lead to tryptophan degradation, the products generated in these processes, their known biological effects, and methods which may be applied to stabilize the amino acid.

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.

Effect of Creatine and Glucose on Formation of Heterocyclic Amines in Grilled Chicken Breasts

The occurrence of heterocyclic amines (HAs) in grilled chicken breasts was investigated. All samples contained HAs, including MeIQx, PhIP, and the β-carbolines harman and norharman. In particular, PhIP was found in concentrations of 1.5-9.1 ng/g, and MeIQx was detected at very low concentrations (n.d.-1.1 ng/g). The concentrations of two co-mutagenic β-carbolines, harman and norharman, ranged from 0.8 to 2.3 ng/g when the content of the precursor glucose was varied from 100 to 620 mg/kg. In contrast, the content of the precursor creatine in non-grilled chicken breasts varied by only 8.6%. A significant linear correlation existed between the molar concentration of PhIP and the molar ratio of creatine/glucose (r = 0.88, p < 0.001). We, thus, conclude that the formation of PhIP may be inhibited with increasing concentrations of glucose in chicken breast. Chicken patties coated with ribose or glucose-containing water in oil emulsions confirmed that both reducing sugars decreased PhIP formation with the preferred concentrations (sensory analysis) of 0.5-1% for ribose and 1% for glucose leading to a reduction of PhIP formation by 28-34% and 39%, respectively.

Heterocyclic Aromatic Amines in Cooked Meat Products: Causes, Formation, Occurrence, and Risk Assessment

Meat products are sources of protein with high biological value and an essential source of other nutrients, such as vitamins and minerals. Heating processes cause food to become more appetizing with changes in texture, appearance, flavor, and chemical properties by the altering of protein structure and other ingredients. During heat treatment, heterocyclic aromatic amines (HAAs), potent mutagens/carcinogens, are formed due to the Maillard reaction. The HAAs are classified in at least 2 groups: thermic HAAs (100 to 300 °C) and pyrolytic HAAs (>300 °C). This review focuses on the parameters and precursors which affect the formation of HAAs: preparation, such as the marinating of meat, and cooking methods, including temperature, duration, and heat transfer, as well as levels of precursors. Additionally, factors are described subject to pH, and the type of meat and ingredients, such as added antioxidants, types of carbohydrates and amino acids, ions, fat, and other substances inhibiting or enhancing the formation of HAAs. An overview of the different analytical methods available is shown to determine the HAAs, including their preparation to clean up the sample prior to extraction. Epidemiological results and human daily intake of HAAs obtained from questionnaires show a relationship between the preference for very well-done meat products with increased HAA levels and an enhanced risk of the incidence of cancer, besides other carcinogens in the diet. The metabolic pathway of HAAs is governed by the activity of several enzymes leading to the formation of DNA adducts or HAA excretion and genetic sensitivity of individuals to the impact of HAAs on human cancer risk.

Bioactive β-carbolines norharman and harman in traditional and novel raw materials for chicory coffee

The β-carboline compounds norharman and harman exhibit neuroactive activity in the human body. Chicory coffee has proved to be a source of β-carboline compounds. This study assessed the norharman and harman contents of traditional and novel raw materials for the production of chicory coffee, as well as in samples of chicory coffee with novel additives. The highest content of the β-carbolines among the traditional raw materials was recorded in roasted sugar beet (2.26 μg/g), while roasting the chicory caused a 25-fold increase in the content of norharman in this raw material (from 0.05 to 1.25 μg/g). In novel raw materials not subjected to the action of high temperature, β-carboline was not detected. Among the roasted novel raw materials, the highest contents of harman and norharman were found in artichokes. High harman levels were also recorded in roasted chokeberry.

Exposure to beta-carbolines norharman and harman

The aromatic beta-carbolines norharman and harman have been implicated in a number of human diseases including Parkinson's disease, tremor, addiction and cancer. It has been shown that these compounds are normal body constituents formed endogenously but external sources have been identified. Here, we summarise literature data on levels of norharman and harman in fried meat and fish, meat extracts, alcoholic drinks, and coffee brews. Other sources include edible and medicinal plants but tobacco smoke has been identified as a major source. Exposure levels from these different dietary sources are estimated to a maximum of 4 microg norharman per kg body weight (bw) per day and 1 microg harman per kg bw per day. Exposure via tobacco smoke depends on smoking habits and type of cigarettes but can be estimated to 1.1 microg/kg bw for norharman and 0.6 microg/kg bw for harman per package of cigarettes smoked. Studies on toxicokinetics indicate that inhalative exposure leads to a rapid increase in plasma levels and high bioavailability of norharman and harman. Oral bioavailability is lower but there are indications that sublingual absorption may increase dietary uptake of beta-carbolines. Endogenous formation can be estimated to be 50-100 ng/kg bw per day for norharman and about 20 ng/kg bw per day for harman but these rates may increase with high intake of precursors. Biomarker studies on plasma levels of beta-carbolines reported on elevated levels of norharman, harman or both in diseased patients, alcoholics and following tobacco smoking or consumption of beta-carboline-containing food. Cigarette smoking has been identified as major influence but dietary exposure may contribute to exposure.

Tryptophan: a precursor for the endogenous synthesis of norharman in man

We investigated whether in healthy subjects L-tryptophan may serve as a precursor for the endogenous synthesis of the beta-carboline norharman. For this purpose subjects, smokers as well as non-smokers, received 0 or 1.2 g of an oral dose of tryptophan. Smokers started the experiment 2 h after cessation of smoking. Plasma levels of tryptophan and norharman were measured 100 and 125 min after the start of the experiment. The levels of both compounds were significantly higher in the group receiving tryptophan. Norharman concentrations in the plasma of smokers were significantly higher than in the non-smoking subjects under both experimental conditions. These results add some proof to the hypothesis that in humans tryptophan may serve as a precursor for the synthesis of norharman.