Controlling Amino Acid Degradations Produced by Reactive

Chapter 3

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Controlling Amino Acid Degradations Produced by Reactive Carbonyls in Foods A Review on the Role of Reaction Conditions for the Preferential Formation of either Flavors or Potentially Toxic Compounds as a Consequence of Carbonyl-Amine Reactions Francisco J. Hidalgo and Rosario Zamora* Instituto de la Grasa, Consejo Superior de Investigaciones Científicas, Carretera de Utrera km 1, Campus Universitario – Edificio 46, 41013-Seville, Spain *E-mail: [email protected]

Amino acid degradations produced as a consequence of carbonyl–amine reactions are an important source of food flavors during food processing, but also of some detrimental compounds which are simultaneously produced. Although these reactions are unavoidably produced to some extent when reactive carbonyls are present, different studies have shown that they can be controlled and directed towards the formation of the most desirable products by regulating reactants and reaction conditions. This review describes the role of the structure and concentration of the involved reactants, the reaction pH, time, and temperature, the presence of oxygen and antioxidants, and the competition among different amino acids and among different reactive carbonyls, on the preferential formation of some amino acid degradation products.

Amino Acid Degradations Produced by Reactive Carbonyls Many food constituents have a carbonyl group. This group is present in some major food constituents, such as carbohydrates, but also in many minor components, such as vitamins, additives, or, for example, the carbonyl compounds produced as a consequence of the lipid oxidation processes. The carbonyl group © 2016 American Chemical Society Granvogl et al.; Browned Flavors: Analysis, Formation, and Physiology ACS Symposium Series; American Chemical Society: Washington, DC, 2016.


is electrophilic and can be attacked by the nucleophilic groups of surrounding molecules. Among them, the amino, hydroxyl, and sulfhydryl groups of amino acids are especially prone to these reactions, constituting the carbonyl-amine reactions one of the main chemical reactions commonly occurring in foods during processing/and storage (1). Carbonyl-amine reactions are a very complex process which embraces a whole network of many different reactions. As a result of it, an extraordinary mixture of compounds in very different amounts are obtained. These reactions are responsible for much of the browning development produced in foods as a result of processing as well as the generation of flavors (2), molecules with antioxidant properties (3), and process-related food toxicants (4). A significant part of these consequences results from amino acid degradations produced by reactive carbonyls. Amino acid degradations initiated by reactive carbonyls produce the conversion of the amino acids into Strecker aldehydes (5, 6), α-oxo acids (7, 8), shorter aldehydes (9), amines (10, 11), olefins (12, 13), and saturated and unsaturated acids (14). The reaction pathways responsible for the formation of the major reaction products have been the objective of numerous investigations and they have been mostly clarified (5, 15, 16). On the other hand, the reaction mechanisms responsible for the formation of other compounds, such as the acids, remains to be fully understood. Figure 1 shows the reaction pathways involved in the formation of the major reaction products formed in a first step: Strecker aldehydes (6), amines (7) and α-oxo acids (5). This figure uses a 4-oxo-alkenal (2) as a model reactive carbonyl compound but similar reaction pathways have been described with other reactive carbonyls. The reaction is initiated with the formation of the corresponding imine between the amino group of the amino acid and the carbonyl group (3a). This imine can suffer then different prototropies. The first one is a keto-enol tautomerism to produce a new imine (3b). This imine is the responsible, after hydrolysis, of the formation of α-oxo acids (5) at the same time that the reactive carbonyl is transformed into a hydroxyamino derivative (8). The prototropy can also occur between the carboxylic and the amino group (3c). This facilities the exit of carbon dioxide and the formation of a relatively stable azomethine ylide. This ylide, which is stabilized by resonance, would be the origin of both Strecker aldehydes (6) and amines (7) by hydrolysis. The formation of any of them would be favored if the corresponding resonance form from which it is produced (4a or 4b, respectively) is preferred. Strecker aldehydes, α-oxo acids and amines are not final reaction products and the conversion of amines and α-oxo acids into Strecker aldehydes (17), the degradation of α-oxo acids and Strecker aldehydes to produce shorter aldehydes (9), and the conversion of amines into olefins (18) has been described. In addition, the conversion of α-amino acids into unsaturated acids by elimination reaction favored by carbonyl compounds (18) can be hypothesized. Therefore, the prototropy exhibited by the imine and the weight of one resonance form over the other will determine the main compound produced. This is important because it will determine whether the reaction will mainly evolve toward either the formation of flavors, mostly related to the formation of Strecker aldehydes and α-oxo acids, or to the production of amines, which are potentially toxic by 24 Granvogl et al.; Browned Flavors: Analysis, Formation, and Physiology ACS Symposium Series; American Chemical Society: Washington, DC, 2016.


themselves and can also be transformed into the vinylogous derivatives of amino acids, some of which of proved toxicity. The objective of this review is both to collect the existing information indicating how the flavor/toxic compound ratio can be shifted towards the formation of either Strecker aldehydes or amines as a function of reaction conditions and to try to understand it on the basis of the reaction mechanism described in Figure 1.

Figure 1. Amino acid degradations produced by reactive carbonyls.

25 Granvogl et al.; Browned Flavors: Analysis, Formation, and Physiology ACS Symposium Series; American Chemical Society: Washington, DC, 2016.


The Structure of the Reactants The structure of the reactants will firstly determine if the imine 3b is preferred over 3c and, secondly, if the electronic distribution in the resonance structure 4 is closer to either 4a or 4b. In the case of the different amino acids, the inductive effect of the side chain of the amino acid should play a role in the preference for one of the imines. To this respect, Hidalgo et al. (19) found that the α-keto acids derived from glutamic acid, methionine and phenylalanine increased more than those derived from alanine, valine, leucine and isoleucine during the curing process of Iberian ham, a process in which carbonyl-amine reactions are known to happen (20). The electron-withdrawing effect of the side chain of the involved amino acid may provide an explanation for the preferential formation of imine 3b in glutamic acid, methionine and phenylalanine. In fact, the conversion of phenylalanine into phenylpyruvic acid has been shown to be produced under very soft reaction conditions (8). These inductive effects of the amino acid side chains are also likely involved in the preferred electronic distribution in the azomethine ylide 4, which will determine the formation of either Strecker aldehydes or amines. Analogously to the effects of side chains in amino acids, the structure of the reactive carbonyl has also been shown to play a major role in the Strecker aldehyde/amine ratio produced. In a recent study, Zamora et al. (21) analyzed a large group of reactive carbonyls and found that alkenals, alkadienals, and hydroxyalkenals produced higher 2-phenylethylamine/phenylacetaldehyde ratios than epoxyalkenals or oxoalkenals under nitrogen but there was not a clear difference among the different lipid oxidation products when the reaction was carried out under air. This is explained according to the role of the chain of the carbonyl compound in the charge distribution of the azomethine ylide 4. Thus, under nitrogen, the presence of electron-withdrawing groups in the chain, such as in oxoalkenals or epoxyalkenals, favored a charge distribution closer to mesomer 4b and, therefore, the formation of the aldehyde. On the contrary, the presence of electron-donating groups, such as alkoxyl or carbon-carbon double bonds, favored a charge distribution closer to mesomer 4a and, therefore, the formation of the amine. In the presence of oxygen, double bonds are oxidized and converted into electro-withdrawing groups. Therefore, under air, there was not a clear difference in the Strecker aldehyde/amine ratio among the reactive carbonyls assayed.

The Concentration of the Reactants The reactive carbonyl 2 is a reactant in the formation of either Strecker aldehydes or α-oxo acids, and the carbonyl group initially involved in the formation of the imine group is finally converted into an amino group (compound 8). Therefore, an increase in the amount of the carbonyl compound should always produce an increase in the formation of either the Strecker aldehyde or the α-keto acid, unless this carbonyl compound is already in excess. This has been usually observed (22). Differently to the formation of either Strecker aldehydes or α-keto acids, the reactive carbonyl 2 is recovered when the amine is produced. Therefore, an increase in the concentration of the carbonyl compound does not guarantee an 26 Granvogl et al.; Browned Flavors: Analysis, Formation, and Physiology ACS Symposium Series; American Chemical Society: Washington, DC, 2016.

increase in the formation of the amine and the Strecker aldehyde/amine ratio will increase (21).


The Reaction pH Strecker aldehydes and α-oxo acids are mainly produced at acid pH values. One of the reasons for that may be related to a predominance of the enolic form 3b over the oxo form 3c, which would be likely protonated in an acid medium. Therefore, under acid conditions, the formation of α-oxo acids (5) should be favored, as found experimentally (8). In addition, acid conditions also favor the formation of Strecker aldehydes (6) over the amine (7) because an electronic distribution closer to that of mesomer 4b is favored by analogous reasons. Furthermore, acid pH values also favor the conversion of amines into Strecker aldehydes in the presence of reactive carbonyls (17). This expected increase of the Strecker aldehyde/amine ratio was confirmed experimentally by heating phenylalanine in the presence of reactive carbonyls under different pH values. The observed aldehyde/amine ratio increased considerably when the pH decreased (21). Although the formation of both, α-oxo acids and Strecker aldehydes are favored under acid conditions, the α-oxo acid/Strecker aldehyde ratio depends on the reaction temperature. At low temperature, α-oxo acids are produced to a higher extent than Strecker aldehydes (8). However, when the temperature increases, the conversion of α-oxo acids into Strecker aldehydes is produced and the Strecker aldehyde may be the main reaction product (8).

The Presence of Oxygen in the Reaction Atmosphere The presence of oxygen in the reaction atmosphere also plays a major role in the Strecker aldehyde/amine ratio. The concentration of Strecker aldehydes and α-oxo acids usually increased with the presence of oxygen (21). However, the oxygen effect is particularly critical in the formation of the amine that can be completely inhibited in the presence of a high oxygen content. The reason for that is the oxidation suffered by the chains of the reactive carbonyls. As described above, when double bonds are oxidized they are converted into electronwithdrawing groups and this favors an electronic distribution closer to that of mesomer 4b.

The Reaction Time and Temperature Formation of α-oxo acids, Strecker aldehydes and amines increases with time and temperature (8, 11, 22). However, an increase of temperature also promotes the reactions of these compounds: their above described transformations among them and their decomposition into secondary degradation products. Therefore, this dependence with the temperature might not always be clearly observed. This is particularly important for α-keto acids, which are thermally sensitive. Thus, the amount of phenylpyruvic acid produced by decomposition 27 Granvogl et al.; Browned Flavors: Analysis, Formation, and Physiology ACS Symposium Series; American Chemical Society: Washington, DC, 2016.


of phenylalanine in the presence of epoxyalkenals was clearly higher than the amount of phenylacetaldehyde produced after 3 h at 60 ºC, but the amount of phenylpyruvic acid was reduced after 24 h and it was lower than the amount of phenylacetaldehyde produced after this time (8). In relation to the Strecker aldehyde/amine ratio, Zamora et al. (21) observed that this ratio was mostly constant at the different assayed temperatures (from 100 to 170 ºC) but it decreased when temperature increased at pH 3 and increased when temperature increased at pH 6. These results might be related to the easiness of conversion of the amine into the aldehyde in the presence of the carbonyl compound at the different temperatures and pH values (17).

The Activation Energies Activation energy is defined as the minimum energy required to start a chemical reaction. Therefore, the comparison among the activation energies of the different reactions involved (not only that of formation of α-oxo acids, Strecker aldehydes or amines, but also the transformations among them and their decompositions) may help to understand the reactions that will be firstly produced. Activation energies depend on the involved reactants but also on the reaction conditions (16). Thus, for example, alkadienals exhibited a lower activation energy than other lipid oxidation products for the conversion of phenylalanine into phenylacetaldehyde (16). This might be surprising according to the mechanism shown in Figure 1 because the carbon-carbon double bond is an electron-donating group and it should not favor an electronic distribution closer to mesomer 4b. However, these activation energies were determined using air in the reaction atmosphere. Under these conditions, double bonds are expected to be oxidized and converted into electron-withdrawing groups that might have an effect higher than those electron-withdrawing groups present in the other reactive carbonyls tested. The effect of reaction conditions on activation energy was also observed, for example, in the formation of acrylamide from 3-aminopropionamide (18). The activation energy of this reaction increased by about 50% when the water activity was increased from 0.6 to 0.95. The side chain of the amino acid also played a major role on the activation energy of the reaction, more likely because of the inductive effects described above. Thus, the activation energy for the conversion of phenylalanine into phenylethylamine was much lower than the conversion of asparagine into 3-aminopropionamide (11, 23). When the amino acid and the reactive carbonyl are fixed, the activation energies for the conversion of an amino acid into either α-keto acid, Strecker aldehyde or the corresponding amine are different. Although the number of activation energies determined so far is limited (16), the available data indicate that the activation energy for the conversion of phenylalanine into phenylpyruvic acid is lower than that for its conversion into phenylacetaldehyde when epoxyalkenals or oxoalkenals were employed as reactive carbonyls. This can be a consequence of a higher preference of the tautomer 3b under the employed reaction conditions. 28 Granvogl et al.; Browned Flavors: Analysis, Formation, and Physiology ACS Symposium Series; American Chemical Society: Washington, DC, 2016.

In addition, the conversion of phenylalanine into β-phenylethylamine had a lower activation energy than the conversion of phenylalanine into phenylacetaldehyde at pH 3 but it had a higher activation energy at pH 6 (21), therefore indicating that reaction conditions play a major role in the preferred routes for amino acid degradation.


The Competition among Amino Acids The introduction of more than one amino acid in the reaction mixture increases considerably the complexity of the produced reactions because some amino acids are transformed into carbonyl compounds which are also able to degrade new amino acids. This has been schematically shown in Figure 2. Thus, for example, Zamora et al. (24) found that the Strecker aldehydes and the α-keto acids produced by carbonyl–amine reactions contributed to the formation of acrylamide. Furthermore, α-keto acids have also been shown to convert amino acids into Strecker aldehydes (25).

Figure 2. The role of amino acids as reactive carbonyl producers on amino acid degradations produced by reactive carbonyls. Abbreviation: RC, reactive carbonyl. 29 Granvogl et al.; Browned Flavors: Analysis, Formation, and Physiology ACS Symposium Series; American Chemical Society: Washington, DC, 2016.


Another possibility, also shown in Figure 2, is that the thermal degradation of amino acids produce reactive carbonyl compounds that can later degrade amino acids. This has been observed for cysteine and serine. These amino acids produced carbonyl compounds by thermal degradation which were able to promote the conversion of amino acids into Strecker aldehydes (26). An additional possibility is the addition of the second amino acid to the reactive carbonyl to produce a new carbonyl compound with different characteristics (Figure 3). Thus, the addition of an amino acid to an alkenal converts the carbon-carbon double bond with relatively low electron-donating properties into an alkylamino group with enhanced electron-donating properties. Therefore, it will induce an increased formation of the amine and a reduced formation of the Strecker aldehyde, which will decrease the Strecker aldehyde/amine ratio, as observed experimentally (27).

Figure 3. The role of amino acids as modifiers of reactive carbonyls on amino acid degradations produced by reactive carbonyls.

The Presence of Antioxidants Although there are not any free radicals involved, addition of many antioxidants with a phenolic structure will also play a role in the reactions collected in Figure 1. However, the contribution of phenolic compounds is not uniform and depends on their structure, in particular the existence of hydroxyl groups in either ortho or meta positions. If phenolic compounds have two hydroxyl groups at meta positions, they exhibit a carbonyl scavenging function (28). Therefore, they are able to scavenge carbonyl compounds and produce carbonyl-phenol adducts. The reaction is very varied and the products formed depend on the kind of carbonyl compound involved. Thus, the reaction of phenolic compounds with saturated carbonyl compounds usually involves the addition of the aromatic carbon of the phenolic compound at the α-position of one of the carbons substituted with one hydroxyl 30 Granvogl et al.; Browned Flavors: Analysis, Formation, and Physiology ACS Symposium Series; American Chemical Society: Washington, DC, 2016.


group to the carbonyl carbon of the carbonyl compound (29). The reaction with 2-alkenals is more complex and involves both the aromatic carbon of the phenolic compound at the α-position of one of the carbons substituted with one hydroxyl group and the hydroxyl group (30). The reaction with more complex carbonyl compounds are not fully understood at present because of the complexity of the produced reactions. In any case, the consequence is always the loss of the carbonyl group and, therefore, the inhibition of the amino acid degradation. Formation of these adducts has been shown to be produced under standard cooking conditions such as deep-frying (31). If phenolic compounds have two hydroxyl groups at ortho positions, they promote amino acid degradations. The reason for such behavior is its easiness to be converted into quinones with similar properties that other reactive carbonyls (31). In fact, activation energies for the conversion of phenylalanine into phenylacetaldehyde under air in the presence of o- and p-diphenols were usually lower than those determined for many carbonyl compounds (32).

The Competition among Reactive Carbonyls The fact that different kinds of carbonyl compounds can produce different amino acid degradations suggests a competition among the different reactive carbonyls. This subject has not been much explored so far. However, it will determine the preferred pathways in complex systems. A recent study of Delgado et al. (32) has determined the existence of an antagonism between lipid-derived reactive carbonyls and phenolic compounds for the Strecker degradation of amino acids. In the case of m-diphenols, this antagonism is explained by a scavenging of the lipid-derived carbonyl by the phenol. In the case of o-diphenols, this antagonism seems to be a consequence of a competition between the phenol and the lipid-derived carbonyl for the amino acid, which decreases the amount of Strecker aldehyde produced. Although it changed as a function of the involved phenolic and carbonyl compounds, the average inhibition observed was about 25% (33).

Conclusions Amino acid degradations are an unavoidable process that takes place when reactive carbonyls are in close contact with amino acids. This is a usual route for the generation of important food flavors during food processing but also of important processing-related food toxicants. However, the different amino acid degradation products are produced by different interrelated pathways, most of which are now clearly understood. This understanding has allowed to suggest ways of promotion of the most desirable compounds at the same time that the most harmful substances are reduced. The results obtained so far suggest that, according to the expected, it is possible to promote the formation of specific products as a function of the structure and concentration of the involved reactants, the reaction pH, time, and temperature, the presence of oxygen and antioxidants, and the competition among different amino acids and different reactive carbonyls. 31 Granvogl et al.; Browned Flavors: Analysis, Formation, and Physiology ACS Symposium Series; American Chemical Society: Washington, DC, 2016.

Acknowledgments We are indebted to José L. Navarro for technical assistance. This study was supported in part by the European Union (FEDER funds) and the Plan Nacional de I + D of the Ministerio de Economía y Competitividad of Spain (Project AGL201568186-R).

References


1.

Zamora, R.; Hidalgo, F. J. Coordinate contribution of lipid oxidation and Maillard reaction to the nonenzymatic food browning. Crit. Rev. Food Sci. Nutr. 2005, 45, 49–59. 2. Newton, A. E.; Fairbanks, A. J.; Golding, M.; Andrewes, P.; Gerrad, J. A. The role of the Maillard reaction in the formation of flavor compounds in dairy products – not only a deleterious reaction but also a rich source of flavor compounds. Food Funct. 2012, 3, 1231–1241. 3. Zhang, X. C.; Tao, N. P.; Wang, X. C.; Chen, F.; Wang, M. F. The colorants, antioxidants, and toxicants from nonenzymatic browning reactions and the impacts of dietary polyphenols on their thermal formation. Food Funct. 2015, 6, 345–355. 4. Zamora, R.; Hidalgo, F. J. 2-Amino-1-methyl-6-phenylimidazo[4,5b]pyridine (PhIP) formation and fate: an example of the coordinate contribution of lipid oxidation and Maillard reaction to the production and elimination of processing-related food toxicants. RSC Adv. 2015, 5, 9709–9721. 5. Rizzi, G. P. The Strecker degradation of amino acids: Newer avenues for flavor formation. Food Rev. Int. 2008, 24, 416–435. 6. Hidalgo, F. J.; Zamora, R. Strecker-type degradation produced by the lipid oxidation products 4,5-epoxy-2-alkenals. J. Agric. Food Chem. 2004, 52, 7126–7131. 7. Ferreira, A. C. D. S.; Reis, S.; Rodrigues, C.; Oliveira, C.; De Pinho, P. G. Simultaneous determination of ketoacids and dicarbonyl compounds, key Maillard intermediates on the generation of aged wine aroma. J. Food Sci. 2007, 72, S314–S318. 8. Zamora, R.; Navarro, J. L.; Gallardo, E.; Hidalgo, F. J. Chemical conversion of α-amino acids into α-keto acids by 4,5-epoxy-2-decenal. J. Agric. Food Chem. 2006, 54, 6101–6105. 9. Chu, F. L.; Yaylayan, V. A. Model studies on the oxygen-induced formation of benzaldehyde from phenylacetaldehyde using pyrolysis GC-MS and FTIR. J. Agric. Food Chem. 2008, 56, 10697–10704. 10. Granvogl, M.; Schieberle, P. Thermally generated 3-aminopropionamide as a transient intermediate in the formation of acrylamide. J. Agric. Food Chem. 2006, 54, 5933–5938. 11. Hidalgo, F. J.; Delgado, R. M.; Navarro, J. L.; Zamora, R. Asparagine decarboxylation by lipid oxidation products in model systems. J. Agric. Food Chem. 2010, 58, 10512–10517. 32 Granvogl et al.; Browned Flavors: Analysis, Formation, and Physiology ACS Symposium Series; American Chemical Society: Washington, DC, 2016.


12. Stadler, R. H.; Blank, I.; Varga, N.; Robert, F.; Hau, J.; Guy, P. A.; Robert, M. C.; Riediker, S. Acrylamide from Maillard reaction products. Nature 2002, 419, 449–450. 13. Zamora, R.; Hidalgo, F. J. Contribution of lipid oxidation products to acrylamide formation in model systems. J. Agric. Food Chem. 2008, 56, 6075–6080. 14. Zamora, R.; Alcón, E.; Hidalgo, F. J. Strecker-type degradation of phenylalanine initiated by 4-oxo-2-alkenals in comparison to that initiated by 2,4-alkadienals, 4,5-epoxy-2-alkenals, or 4-hydroxy-2-nonenal. J. Agric. Food Chem. 2013, 61, 10231–10237. 15. Yaylayan, V. A.; Stadler, R. H. Acrylamide formation in food: A mechanistic perspective. J. AOAC Int. 2005, 88, 262–267. 16. Hidalgo, F. J.; Zamora, R. Amino acid degradations produced by lipid oxidation products. Crit. Rev. Food Sci. Nutr. 2016, 56, 1242–1252. 17. Zamora, R.; Delgado, R. M.; Hidalgo, F. J. Chemical conversion of phenylethylamine into phenylacetaldehyde by carbonyl-amine reactions in model systems. J. Agric. Food Chem. 2012, 60, 5491–5496. 18. Zamora, R.; Delgado, R. M.; Hidalgo, F. J. Conversion of 3-aminopropionamide and 3-alkylaminopropionamides into acrylamide in model systems. Mol. Nutr. Food Res. 2009, 53, 1512–1520. 19. Hidalgo, F. J.; Navarro, J. L.; Delgado, R. M.; Zamora, R. Determination of α-keto acids in pork meat and Iberian ham via tandem mass spectrometry. Food Chem. 2013, 140, 183–188. 20. Ramirez, R.; Cava, R. Volatile profiles of dry-cured meat products from three different Iberian x Duroc genotypes. J. Agric. Food Chem. 2007, 55, 1923–1931. 21. Zamora, R.; Leon, M. M.; Hidalgo, F. J. Oxidative versus non-oxidative decarboxylation of amino acids: conditions for the preferential formation of either Strecker aldehydes or amines in amino acid/lipid-derived reactive carbonyl model systems. J. Agric. Food Chem. 2015, 63, 8037–8043. 22. Zamora, R.; Gallardo, E.; Hidalgo, F. J. Model studies on the degradation of phenylalanine initiated by lipid hydroperoxides and their secondary and tertiary oxidation products. J. Agric. Food Chem. 2008, 56, 7970–7975. 23. Zamora, R.; Delgado, R. M.; Hidalgo, F. J. Formation of β-phenylethylamine as a consequence of lipid oxidation. Food Res. Int. 2012, 46, 321–325. 24. Zamora, R.; Delgado, R. M.; Hidalgo, F. J. Strecker aldehydes and α-keto acids, produced by carbonyl–amine reactions, contribute to the formation of acrylamide. Food Chem. 2011, 128, 465–470. 25. Hidalgo, F. J.; Delgado, R. M.; Zamora, R. Intermediate role of α-keto acids in the formation of Strecker aldehydes. Food Chem. 2013, 141, 1140–1146. 26. Hidalgo, F. J.; Alcón, E.; Zamora, R. Cysteine- and serine-thermal degradation products promote the formation of Strecker aldehydes in amino acid reaction mixtures. Food Res. Int. 2013, 54, 1394–1399. 27. Hidalgo, F. J.; Leon, M. M.; Zamora, R. Amino acid decarboxylations produced by lipid-derived reactive carbonyls in amino acid mixtures. Food Chem. 2016, 209, 256–261. 33 Granvogl et al.; Browned Flavors: Analysis, Formation, and Physiology ACS Symposium Series; American Chemical Society: Washington, DC, 2016.


28. Salazar, R.; Arambula-Villa, G.; Hidalgo, F. J.; Zamora, R. Structural characteristics that determine the inhibitory role of phenolic compounds on 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) formation. Food Chem. 2014, 151, 480–486. 29. Cheng, K. W.; Wong, C. C.; Cho, C. K.; Chu, I. K.; Sze, K. H.; Lo, C.; Chen, F.; Wang, M. Trapping of phenylacetaldehyde as a key mechanism responsible for naringenin’s inhibitory activity in mutagenic 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine formation. Chem. Res. Toxicol. 2008, 21, 2026–2034. 30. Hidalgo, F. J.; Zamora, R. 2-Alkenal-scavenging ability of m-diphenols. Food Chem. 2014, 160, 118–126. 31. Zamora, R.; Aguilar, I.; Granvogl, M.; Hidalgo, F. J. Toxicologically relevant aldehydes produced during the frying process are trapped by food phenolics. J. Agric. Food Chem. 2016, 64, 5583–5589. 32. Delgado, R. M.; Zamora, R.; Hidalgo, F. J. Contribution of phenolic compounds to food flavors: Strecker-type degradation of amines and amino acids produced by o- and p-diphenols. J. Agric. Food Chem. 2015, 63, 312–318. 33. Delgado, R. M.; Hidalgo, F. J.; Zamora, R. Antagonism between lipid-derived reactive carbonyls and phenolic compounds in the Strecker degradation of amino acids. Food Chem. 2016, 194, 1143–1148.

34 Granvogl et al.; Browned Flavors: Analysis, Formation, and Physiology ACS Symposium Series; American Chemical Society: Washington, DC, 2016.

Controlling Amino Acid Degradations Produced by Reactive

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