Alkylresorcinols trap malondialdehyde in whole grain crackers.

To study the alkylresorcinols ability to trap lipid oxidation products in foods, crackers were prepared with either whole grain rye, wheat, spelt, or oat flour, and either sunflower or linseed oil, and were stored for up to 36 days at room temperature. During storage, polyunsaturated fatty acyl chains degraded, malondialdehyde was produced, and alkylresorcinol content decreased. At the end of the storage, alkylresorcinol content in crackers was reduced by 61-78 % and a part of disappeared alkyresorcinols (3-8 %) appeared as malondialdehyde/alkylresorcinol adducts.

Formation of phenazines, phenoxazines, and benzoxazoles in the browning reactions of o-quinones.

Quinone-induced browning is widely produced in foods and is mostly considered a consequence of quinone/nucleophile reactions. However, even in the absence of amino acids or proteins, o-quinones develop browning. In an attempt to better understand the reaction pathways involved in this browning development, this study describes the reactions of 4-methyl-1,2-benzoquinone with alcohols, ammonia, and short chain aldehydes.

Addition of olivetol to crackers decreases malondialdehyde content and produces malondialdehyde-olivetol adducts.

This study was undertaken to investigate the malondialdehyde-trapping ability by m-diphenols and the consequent decrease of malondialdehyde in foods. Olivetol was added to crackers, which were prepared with wheat flour and either oxidized or fresh sunflower, linseed, and camelina oils. When crackers were prepared with oxidized oils, olivetol-containing crackers contained less malondialdehyde (∼30%) than control crackers.

Quality and Nutritional Changes of Traditional Cupcakes in the Processing and Storage as a Result of Sunflower Oil Replacements with Refined Olive Pomace Oil.

Recent nutritional studies have shown that the regular consumption of olive pomace oil (OPO) contributes to cardiovascular and cardiometabolic disease prevention. OPO could be a healthier alternative to the polyunsaturated oils employed in a number of bakery foods. However, little is known about the quality and nutritional changes of OPO in these products, especially the amounts of its bioactive components that finally reach consumers.

Carbonyl-trapping by phenolics and the inhibition of the formation of carcinogenic heterocyclic aromatic amines with the structure of aminoimidazoazaarene in beef patties.

Carcinogenic heterocyclic aromatic amines (HAAs) with the structure of aminoimidazoazaarene (PhIP, MeIQx, IQ, and MeIQ) are produced by reaction of creatin(in)e, ammonia, and reactive carbonyls (phenylacetaldehyde, acrolein, and crotonaldehyde). In an attempt to provide efficient methodologies for HAA reduction in beef patties, this study: identified phloroglucinol as the most efficient phenolic to reduce HAA formation (76-96% inhibition); isolated and characterized by NMR and MS phloroglucinol/phenylcetaldehyde and phloroglucinol/acrolein adducts; and determined by LC-MS/MS adduct formation in beef patties treated with phloroglucinol. Obtained results suggested that addition of trihydroxyphenols (including phloroglucinol) to beef patties should decrease HAA formation.

Malondialdehyde trapping by food phenolics.

The reactions between malondialdehyde and 2,5-dimethylresorcinol, orcinol, olivetol, and alkylresocinols were studied in an attempt to investigate both if this lipid oxidation product is trapped by phenolics analogously to other reactive carbonyls and to elucidate the chemical structures of the produced adducts. After being formed, malondialdehyde is both partially fractionated to acetaldehyde and oligomerized into dimers and trimers. All these compounds react with phenolics producing three main kinds of derivatives: 5(or 7)-alkyl-7(or 5)-hydroxy-4-methyl-4H-chromene-3-carbaldehydes, 7-alkyl-9-hydroxy-6H-2,6-methanobenzo[d][1,3]dioxocine-5-carbaldehydes, and 4-(3-formylphenyl)-7-hydroxy-4H-chromene-3-carbaldehydes.

Ketone-phenol reactions and the promotion of aromatizations by food phenolics.

Heating of either 3,5-heptadien-2-one or 2,6-heptanedione in the presence of ammonia produced 2,6-dimethylpyridine, and also 3-methylcyclohex-2-en-1-one for the second ketone. When phenolics were present, inhibition of pyridine formation was only observed in mixtures of 3,5-heptadien-2-one and resorcinol. This inhibition was due to the formation of ketone-resorcinol adducts, which were isolated and identified by nuclear magnetic resonance (NMR) and mass spectrometry (MS) as 2,4-dimethyl-5,6-dihydro-4H-2,6-methanobenzo[d][1,3]dioxocin-9-ol and 1-(7-hydroxy-4-methylchroman-2-yl)propan-2-one.

Carbonyl-trapping abilities of 5-alkylresorcinols.

In an attempt to investigate the carbonyl-trapping abilities of 5-alkylresorcinols, this study describes the role of these compounds in inhibiting the formation of the 2,5-dialkylpyridines (5-ethyl-2-methylpyridine, 5-butyl-2-propylpyridine, and 5-hexyl-2-pentylpyridine) produced by 2-alkenals (crotonaldehyde, 2-hexenal, and 2-octenal) in the presence of ammonia. 5-Alkylresorcinols (as well as orcinol and olivetol) inhibited the formation of pyridines to an extend that depended on the 2-alkenal involved and the reaction conditions. This inhibition was consequence of the trapping of 2-alkenals by the phenolics.

Carbonyl Chemistry and the Formation of Heterocyclic Aromatic Amines with the Structure of Aminoimidazoazaarene.

Recent studies have shown that the formation of heterocyclic aromatic amines (HAAs) with the structure of aminoimidazoazaarene is produced by reaction of specific reactive carbonyls with ammonia and creatin(in)e. These carbonyl compounds, which are usually the limiting reagents, have multiple origins. Therefore, HAA formation cannot be considered to be produced as a consequence of a single process, such as the Maillard reaction, but of any process that generates the involved reactive carbonyls.

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.

Identification of acrolein as the reactive carbonyl responsible for the formation of 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx).

Reaction mixtures of reactive carbonyls and creatinine were submitted to high temperature and studied to identify the reactive carbonyl(s) responsible for 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx) formation. MeIQx was produced by reaction of acrolein and creatinine within a wide pH range and with an activation energy of 81.1 ± 1.

Identification of Precursors and Formation Pathway for the Heterocyclic Aromatic Amine 2-Amino-3-methylimidazo(4,5-)quinoline (IQ).

Food processing is responsible for the destruction of some health hazards, but it is responsible for the formation of new ones. Among them, the formation of heterocyclic aromatic amines (HAAs) has received a considerable attention because of their carcinogenicity. In spite of this, HAA formation is still poorly understood.

Formation of 3-hydroxypyridines by lipid oxidation products in the presence of ammonia and ammonia-producing compounds.

Pyridines are produced during food processing and are important flavor compounds. In spite of that, their formation pathways are still poorly understood, in particular those related to 3-hydroxypyridines. In an attempt to fill this gap, this study describes, for the first time, precursors and reaction pathways leading to 3-hydroxypyridine formation.

Reactive carbonyls and the formation of the heterocyclic aromatic amine 2-amino-3,4-dimethylimidazo(4,5-f)quinoline (MeIQ).

Reactions involving reactive carbonyls, creatinine, and ammonia-producing compounds were investigated in order to clarify the formation of the heterocyclic aromatic amine (HAA) 2-amino-3,4-dimethylimidazo(4,5-f)quinoline (MeIQ). Obtained results showed that MeIQ was only produced when 2-butenal (crotonaldehyde) was present. Reaction yields depended on the pH, with a maximum around pH 6.

Conversion of 5-Hydroxymethylfurfural into 6-(Hydroxymethyl)pyridin-3-ol: A Pathway for the Formation of Pyridin-3-ols in Honey and Model Systems.

The formation of 6-(hydroxymethyl)pyridin-3-ol by ring expansion of 5-(hydroxymethyl)furfural (HMF) in the presence of ammonia-producing compounds was studied to determine the routes of formation of pyridin-3-ols in foods. 6-(Hydroxymethyl)pyridin-3-ol was produced from HMF in model systems, mostly at neutral pH values, as a function of reaction times and temperature and with an activation energy () of 74 ± 3 kJ/mol, which was higher than that of HMF disappearance (43 ± 4 kJ/mol). A reaction pathway is proposed, which is general for the formation of pyridin-3-ols from 2-oxofurans.

Formation of heterocyclic aromatic amines with the structure of aminoimidazoazarenes in food products.

Thermal food processing has many beneficial consequences, although it also produces some unintentional undesired effects, such as the formation of potentially mutagenic and carcinogenic substances. Among them, the formation of heterocyclic aromatic amines (HAAs) has been related to the declared carcinogenicity of processed meats. In spite of this importance, HAA formation pathways remain mostly unknown, which avoids the design of targeted procedures to inhibit HAA appearance.

Polyphenolic Extract (PE) from Olive Oil Exerts a Potent Immunomodulatory Effect and Prevents Graft-versus-Host Disease in a Mouse Model.

Polyphenols are a group of chemical substances found in plants, with immunomodulatory, antiproliferative, and anti-inflammatory properties that might be useful in the prophylaxis and treatment of graft-versus-host disease (GVHD). Polyphenolic extract (PE) obtained from extra virgin olive oil (EVOO) decreased the activation and proliferation of activated T cells. In addition, a decreased production of proinflammatory cytokines was observed upon exposure to PE.

Oligomerization of reactive carbonyls in the presence of ammonia-producing compounds: A route for the production of pyridines in foods.

The reactions of different lipid-derived reactive carbonyls with ammonia-producing compounds were studied to investigate the formation of pyridines in foods. 2-Alkyl, 3-alkyl-, and 2,5-dialkylpyiridines were produced by oligomerization of short-chain aldehydes in the presence of ammonia. Thus, acetaldehyde/crotonaldehyde mixtures and 2,4-alkadienals were the main responsible for the formation of 2-alkylpyridines; acrolein or 2,4-alkadienals were needed for the formation of 3-alkylpyridines; and 2-alkenals were responsible for the formation of 2,5-dialkylpyridines.

Formation of phenylacetic acid and benzaldehyde by degradation of phenylalanine in the presence of lipid hydroperoxides: New routes in the amino acid degradation pathways initiated by lipid oxidation products.

Lipid oxidation is a main source of reactive carbonyls, and these compounds have been shown both to degrade amino acids by carbonyl-amine reactions and to produce important food flavors. However, reactive carbonyls are not the only products of the lipid oxidation pathway. Lipid oxidation also produces free radicals.

Characterization of Carbonyl-Phenol Adducts Produced by Food Phenolic Trapping of 4-Hydroxy-2-hexenal and 4-Hydroxy-2-nonenal.

4-Hydroxy-2-alkenals disappear in the presence of food phenolics (i.e., cathechin or quercetin), and the corresponding carbonyl-phenol adducts are produced.

Structure-Activity Relationship (SAR) of Phenolics for the Inhibition of 2-Phenylethylamine Formation in Model Systems Involving Phenylalanine and the 13-Hydroperoxide of Linoleic Acid.

Lipid hydroperoxides have been shown to produce amino acid decarboxylations. Because thermal decomposition of lipid hydroperoxides produces free radicals and reactive carbonyls, and phenolic compounds have been shown to scavenger both of them, phenolics are expected to inhibit these reactions and this protection should depend on the structures of the involved phenolics. In this study, the effect of a wide array of phenolics and their mixtures on 2-phenylethylamine formation by phenylalanine degradation in the presence of the 13-hydroperoxide of linoleic acid (LOOH) was studied.

2,4-Alkadienal trapping by phenolics.

Phenolics can trap lipid-derived reactive carbonyls as a protective function that diminishes the broadcasting of the lipid oxidative damage to food macromolecules. In an attempt to clarify the trapping of 2,4-alkadienals by phenolics, this study analyzes the reactions of 2,4-hexadienal, 2,4-heptadienal, and 2,4-decadienal with 2-methylresorcinol. These reactions produced (E)-4-(alk-1-en-1-yl)-8-methyl-2,7-bis(prop-1-en-2-yloxy)chromanes, which were isolated and characterized by 1D and 2D NMR and MS.

Carbonyl-Phenol Adducts: An Alternative Sink for Reactive and Potentially Toxic Lipid Oxidation Products.

Different from the well-characterized function of phenolics as antioxidants, their function as lipid-derived carbonyl scavengers is mostly unknown. However, phenolics react with lipid-derived carbonyls as a function of the nucleophilicity of their reactive groups and the electronic effects and steric hindrances present in the reactive carbonyls. Furthermore, the reaction produces a wide variety of carbonyl-phenol adducts, some of which are stable and have been isolated and characterized but others polymerize spontaneously.

Structure-Activity Relationship (SAR) of Phenolics for 2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) Formation in Phenylalanine/Creatinine Reaction Mixtures Including (or Not) Oxygen and Lipid Hydroperoxides.

Phenolics can act as either promoters or inhibitors in 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) formation. In an attempt to clarify the structure-activity relationship (SAR) of phenolics for this reaction, the formation of PhIP in mixtures of phenylalanine, creatinine, 13-hydroperoxide of linoleic acid (LOOH) or 4-oxo-2-nonenal, and a wide array of phenolics was studied in the presence and in the absence of oxygen. The obtained results suggested that those phenolics having a high carbonyl scavenging ability inhibited the formation of PhIP.

Phenolic trapping of lipid oxidation products 4-oxo-2-alkenals.

The reaction between 4-oxo-2-alkenals (fumaraldehyde, 4-oxo-2-hexenal, and 4-oxo-2-nonenal) and phenolic compounds (resorcinol and 2-methylresorcinol) was studied to characterize the trapping ability of phenolic compounds for these lipid oxidation products. The reaction occurred rapidly under neutral or slightly basic conditions and different carbonyl-phenol adducts were produced. However, these compounds were unstable and their stabilization had to be achieved by means of either acetylation or reduction with sodium borohydride.