The Inhibition of Maillard Browning by Different Concentrations of Rosmarinic Acid and Epigallocatechin-3-Gallate in Model, Bakery, and Fruit Systems

Inhibition of Browning in Apples Using Betacyclodextrin-Assisted Extracts of Green Rooibos (Aspalathus linearis)

Green rooibos' bioactive compounds contribute greatly towards its antioxidant activity. The anti-browning activity of aqueous (GRE) and beta-cyclodextrin (β-GRE)-assisted extracts of green rooibos was investigated in canned apples. Freeze-dried extracts (GRE and β-GRE) obtained at 40 °C for 60 min were added in canned apples at 0.25 and 0.5% prior to heat processing and stored at 23 and 37 °C for 24 weeks. Lightness (L*), colour difference (DE*), furfural and hydroxymethyl furfural (HMF) were determined to establish the effect of extracts against non-enzymatic browning (NEB) development. The L* value decreased, whereas DE*, HMF and furfural increased with increased storage time and temperature. A higher inhibition was observed for samples stored at 23 °C, and storage at 37 °C reduced (p < 0.05) the inhibitory capacity of extracts. Greater inhibition against NEB development was reported for β-GRE 0.25 and 0.5 via the L* value (40.93-46.67%), β-GRE 0.25 for DE* (46.67%) and β-GRE 0.25 and 0.5 for HMF (59.55-67.33%). No differences (p > 0.05) were observed in furfural inhibition between all extracts, although inhibition was reported at 62.69-72.29%. Browning inhibition correlated with the reaction rate constant (k₀) and activation energy (Ea), exhibiting a correlation coefficient of 0.925, 0.964, 0.932 and 0.754 for L*, DE*, HMF and furfural, respectively.

Chemical Contamination in Bread from Food Processing and Its Environmental Origin

Acrylamide (AA), furan and furan derivatives, polycyclic aromatic amines (PAHs), monochloropropanediols (MCPDs), glycidol, and their esters are carcinogens that are being formed in starchy and high-protein foodstuffs, including bread, through baking, roasting, steaming, and frying due to the Maillard reaction. The Maillard reaction mechanism has also been described as the source of food processing contaminants. The above-mentioned carcinogens, especially AA and furan compounds, are crucial substances responsible for the aroma of bread. The other groups of bread contaminants are mycotoxins (MTs), toxic metals (TMs), and pesticides. All these contaminants can be differentiated depending on many factors such as source, the concentration of toxicant in the different wheat types, formation mechanism, metabolism in the human body, and hazardous exposure effects to humans. The following paper characterizes the most often occurring contaminants in the bread from each group. The human exposure to bread contaminants and their safe ranges, along with the International Agency for Research on Cancer (IARC) classification (if available), also have been analyzed.

Controlled Formation of Pyrazines: Inhibition by Ellagic Acid Interaction with N-(1-Deoxy-d-xylulos-1-yl)-glycine and Promotion through Ellagic Acid Oxidation

The effect of ellagic acid on the formation of pyrazine, methylpyrazine, 2,3-methylpyrazine, 2,6-methylpyrazine, 2,5-methylpyrazine, and trimethylpyrazine in the xylose-glycine Maillard reaction model was researched. Ellagic acid could either inhibit or promote pyrazine formation, depending on its addition time point and the pH of the system. The addition of ellagic acid during the accumulation period of an Amadori compound inhibited pyrazine formation by capturing the Amadori compound in the xylose-glycine Maillard system and decreasing the pyrazine precursors. The inhibitory effect of ellagic acid on pyrazine formation got more obvious with an increase in the pH of the system. However, when ellagic acid was added at the beginning of the xylose and glycine Maillard system and when the oxidizing substances such as glyoxal and methylglyoxal were significantly formed in the Maillard system, its oxidation could promote the formation of pyrazines.

Shedding Light on the Volatile Composition of Broa, a Traditional Portuguese Maize Bread

In Portugal, maize has been used for centuries to produce an ethnic bread called broa, employing traditional maize varieties, which are preferred by the consumers in detriment of commercial hybrids. In order to evaluate the maize volatiles that can influence consumers’ acceptance of broas, twelve broas were prepared from twelve maize varieties (eleven traditional and one commercial hybrid), following a traditional recipe. All maize flours and broas were analyzed by HS-SPME-GC-MS (headspace solid-phase microextraction) and broas were appraised by a consumer sensory panel. In addition, the major soluble phenolics and total carotenoids contents were quantitated in order to evaluate their influence as precursors or inhibitors of volatile compounds. Results showed that the major volatiles detected in maize flours and broas were aldehydes and alcohols, derived from lipid oxidation, and some ketones derived from carotenoids’ oxidation. Both lipid and carotenoids’ oxidation reactions appeared to be inhibited by soluble phenolics. In contrast, phenolic compounds appeared to increase browning reactions during bread making and, consequently, the production of pyranones. Traditional samples, especially those with higher contents in pyranones and lower contents in aldehydes, were preferred by the consumer sensory panel. These findings suggest that, without awareness, consumers prefer broas prepared from traditional maize flours with higher contents in health-promoting phenolic compounds, reinforcing the importance of preserving these valuable genetic resources.

Incorporation of polyphenols in baked products

Bakery foods, including breads, cakes, cookies, muffins, rolls, buns, crumpets, pancakes, doughnuts, waffles, and bagels, etc., have been an important diet of humans for thousands of years. As the nutraceuticals with various biological activities, polyphenols, especially polyphenol-enriched products are widely used in bakery foods. The polyphenol-enriched products are mainly from fruits and vegetables, including fruits in whole, juice, puree, jam, and the powder of dried fruits, pomace, and peels. Incorporation of these products not only provide polyphenols, but also supply other nutrients, especially dietary fibers for bakery products. This chapter discussed the thermal stability of different types of polyphenols during baking, and the effect of polyphenols on the sensory attributes of baked foods. Moreover, their role in mitigation of reactive carbonyl species and the subsequent formation of advanced glycation end products, antioxidant and antimicrobial activities have been also discussed. Since polyphenols are subjected to high temperature for dozens of minutes during baking, future works need to focus on the chemical interactions of polyphenols and their oxidized products (quinones) with other food components, and the safety consequence of these interactions.

Polysaccharides and polyphenol in dried Morinda citrifolia fruit tea after different processing conditions: Optimization analysis using response surface methodology

The increasing popularity of Morinda citrifolia has many medical and health benefits because of its rich polysaccharides (PSC) and polyphenols (PPN). It has become popular to brew the dry M. citrifolia fruit slice as tea in some regions of China. In this study, optimize the extraction parameters of M. citrifolia fruit tea polysaccharides and polyphenols using response surface methodology. The results indicated the highest PSC yield of 17% at 46 °C for 11 min and the ratio of water/M. citrifolia fruit powder was 78 mL/g. The optimum extraction of PPN was at 95 °C for 10 min and the ratio of water/M. citrifolia fruit powder 90 mL/g, with 8.93% yield. Using dry M. citrifolia fruit slices as a tea is reported for the first time. Based on the results, the maximum level of PSC can be obtained under condition by infusing about four dried M. citrifolia fruit slice with average thickness and size in warm boiled water for 11 min, taking a 300 mL cup (300 mL of water) for example. The maximum level of PPN can be obtained by adding three slices of dried M. citrifolia fruit slice to boiled water for 10 min. Considering the powder used in our study, the further pulverization of cutting into powder is more conducive to material precipitation. This study provides a scientific basis for obtaining PSC and PPN from dry M. citrifolia fruit slice tea by brewing.

Effect of Addition of Green Coffee Parchment on Structural, Qualitative and Chemical Properties of Gluten-Free Bread

Green coffee parchment (GCP) is becoming interesting, due to the diffusion of wet processing in which coffee parchment is collected separately; it is one of the less studied coffee by-products, but it is reported to be rich in phenolic compounds and dietary fiber. The addition of GCP (355–500 μm) at 2% to gluten-free breads was investigated in terms of physical properties (volume, moisture content, water activity, crumb grain, texture, and color), total antioxidant capacity (TAC) and total phenol content during three days of storage. Moreover, the effects of GCP on sensorial characteristics, 5-hydroxymethylfurfural (HMF), and oxidative stability was evaluated. From the sensorial analysis, bread with 2% addition resulted in being acceptable for consumers with no significant differences from the control, while 4% of GCP was discarded by consumers, as it resulted in being too bitter. Moreover, GCP at 2% addition did not modify volume, moisture content, and water activity. On the contrary, GCP deeply affected the color with a darker aspect that was appreciated by consumers. Regarding texture, 2% of GCP did not affect hardness, cohesiveness, and staling process during storage. Interestingly, 2% of GCP significantly improved the TAC and oxidative stability of the bread; in accordance with these results, 2% of GCP reduced the HMF content, thanks to its antioxidant compounds.

Investigation on the mitigation effects of furfuryl alcohol and 5-hydroxymethylfurfural and their carboxylic acid derivatives in coffee and coffee-related model systems

The mitigation of furfuryl alcohol, 5-hydroxymethylfurfural, 2-furoic acid, and 5-hydroxymethyl 2-furoic acid was conducted in two dry model systems mimicking coffee and an actual coffee system by incorporating 14 chemicals, that are categorized to phenolic acids, flavonoids, non-phenolic antioxidants, and non-antioxidant agents. Mitigation effects were determined as the decrease in the levels of the studied furan derivatives after the systems went through a controlled roasting process. Strong mitigation effects in the dry model systems were observed after the application of phenolic acids, quinic acid or EDTA. The mitigation effects of phenolic acids and flavonoids depended on the number and availability of phenolic hydroxyl groups. Certain agents exhibited a furan derivative-specific reducing effect while most of them showed a generalized effect. The mitigation efficacy decreased with the increasing complexity of the tested systems. In the coffee system, mitigation effects were almost completely lost in comparison with dry model systems. Still, taurine and sodium sulfite exerted the strongest mitigation effect in the coffee system.

Adducts Derived from (-)-Epigallocatechin Gallate-Amadori Rearrangement Products in Aqueous Reaction Systems: Characterization, Formation, and Thermolysis

The interaction mechanism of (-)-epigallocatechin gallate (EGCG) with Amadori compound (Amadori rearrangement product, ARP) in xylose-alanine model reaction systems was investigated. The adducts between ARP and EGCG were identified as two ARP-EGCG isomers, two ARP-EGCG-H₂O isomers, and multiple ARP-deoxypentosone (DP)-EGCG isomers. The structure of an isolated and purified ARP-EGCG adduct was analyzed by means of Fourier transform infrared spectroscopy, ultraviolet-visible spectroscopy, liquid chromatography-time-of-flight (TOF)-mass spectrometry (LC-TOF-MS), and nuclear magnetic resonance (NMR). Using the two-dimensional NMR analyses, the structure of ARP-EGCG adducts was clarified to consist of a covalent linkage between the C₁₂ position of the ARP and the C₈ position of the A-ring of EGCG, presumably generated by the nucleophilic nature of the EGCG or aromatic substitution reactions. The results showed that slightly alkaline pH and higher temperature could facilitate this reaction. Additionally, the thermal stability of ARP-EGCG and its degradation products revealed that the decomposition pathways of this adduct altered the classic decomposition pathway of ARP, resulting in a lower browning rate and blocking the subsequent Maillard reaction.

Impact of inert and inhibitor baking atmosphere on HMF and acrylamide formation in bread

The baking in N₂ and CO₂ atmosphere decreased by 50% the acrylamide, while this level was 99% in SO₂. The highest acrylamide content was detected in the control sample as 39.03 µg/kg. Additionally, the lowest HMF content was determined in S-bread as 14.85 mg/kg. The baking atmosphere has a significant impact on L* and a* colour values of bread. The highest L* value was measured in S-bread as 71.2, whereas it was the lowest in the control sample as 49.1. According to the Pearson results, acrylamide showed a negative correlation between L* value. However, no correlation was detected between colour values and HMF. Acrylamide had a positive correlation with flavour, although it did not affect the taste features of bread. No correlation between HMF and sensory properties was determined. The result of the study suggested that inert or inhibitor baking atmosphere may help prevent the Maillard reactions in bakery products.

Healthy eating recommendations: good for reducing dietary contribution to the body's advanced glycation/lipoxidation end products pool?

The present review aims to give dietary recommendations to reduce the occurrence of the Maillard reaction in foods and in vivo to reduce the body's advanced glycation/lipoxidation end products (AGE/ALE) pool. A healthy diet, food reformulation and good culinary practices may be feasible for achieving the goal. A varied diet rich in fresh vegetables and fruits, non-added sugar beverages containing inhibitors of the Maillard reaction, and foods prepared by steaming and poaching as culinary techniques is recommended. Intake of supplements and novel foods with low sugars, low fats, enriched in bioactive compounds from food and waste able to modulate carbohydrate metabolism and reduce body's AGE/ALE pool is also recommended. In conclusion, the recommendations made for healthy eating by the Spanish Society of Community Nutrition (SENC) and Harvard University seem to be adequate to reduce dietary AGE/ALE, the body's AGE/ALE pool and to achieve sustainable nutrition and health.

Changes of 5-hydroxymethyl-2-furfural in fresh and processed ginsengs

The study estimated changes of 5-hydroxymethyl-2-furfuraldehyde (5-HMF) in different ginseng products with different temperatures and time pretreatment. Heat treatment was performed at various temperatures for 1.50, 2.00, 2.50, and 3.00 hr, respectively. Ultrasonic extraction and reflux extraction were used to evaluate the extraction rate and different solvents (such as 80% methanol, dichloromethane, ethyl acetate, and an extraction with both dichloromethane and ethyl acetate solvents) using two extraction methods (liquid-liquid extraction and solid-phase extraction) to remove matrix interference. An ultraperformance liquid chromatography-mass spectrometer (UPLC-MS) method was used for quantitative and changing analysis of 5-HMF in different ginseng samples. The results indicated that the content of 5-HMF increased dramatically with heating temperature and time, and the 5-HMF in the ginseng samples ranged from 0.01 to 112.32 g/kg protein. The highest value was observed in the honey-added ginseng samples with the highest amount of addition and highest temperature treatment, and the lowest value was found in the fresh ginseng samples. These results implied that 5-HMF may be as an indicator to estimate the honey addition level and heat treatment degree during the processing of ginseng products, and the content of 5-HMF is a promising parameter to evaluate the quality of products (ginseng). The production and regulation of potentially harmful Maillard reaction products (PHMRPs)-5-HMF in ginseng manufacture will provide an important reference for safe ginseng processing.

Timely Addition of Glutathione for Its Interaction with Deoxypentosone To Inhibit the Aqueous Maillard Reaction and Browning of Glycylglycine-Arabinose System

The inhibitory effects of glutathione (GSH) and oxiglutathione (GSSG) on Maillard browning were compared, and it was clarified that free sulfhydryl was the key substance for the inhibition. The Amadori rearrangement product (ARP) derived from glycylglycine (Gly-Gly) and arabinose (Ara) was prepared by aqueous Maillard reaction, and LC-MS/MS was used to investigate the reaction products of GSH and purified ARP. Reaction between GSH and deoxypentosone (DP) was found to alter the pathway of aqueous Maillard reaction, which reduced the production of glyoxal, methylglyoxal, and furfural and thereby inhibited the formation of melanoidins. To determine the optimal conditions for browning inhibition, a stepwise increase of temperature was used to prepare Maillard reaction products (MRPs). The results showed that the optimum browning inhibitory effect was obtained by adding GSH after Gly-Gly and Ara heating at 80 °C for 60 min.

Positive and negative effects of polyphenol incorporation in baked foods

Polyphenols are hot research topics worldwide owing to their physiological and pharmaceutical activities. Polyphenols and polyphenol-enriched by-products have been widely used in bakery foods because of their neutraceutical properties. This review summarizes the classification, biosynthesis, main source and analysis of polyphenols and intensively discusses the effects of their incorporation in baked foods. The positive effects of polyphenol incorporation include elevation of antioxidant activity of baked foods, scavenging of food-borne toxins produced during thermal processing and decreasing postprandial serum glucose level. Meanwhile, polyphenol incorporation negatively influences colour, texture and flavour of baked foods and bioavailability of the added polyphenols. Most polyphenols are thermally sensitive and reactive. Thus far, few studies have investigated on neoformed compounds from the reaction of polyphenols or their oxidised products (quinones) with other food components. Before launching polyphenol-incorporated bakery foods in the market, future work should focus on full toxicological evaluation of newly derived compounds from polyphenols.

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.

Phenolic compounds reduce formation of Nε-(carboxymethyl)lysine and pyrazines formed by Maillard reactions in a model bread system

This study had the objective of determining the antiglycation activity of phenolic compounds (PCs) ((+)-catechin, quercetin, gallic, ferulic, and caffeic acids) added to a model bread with regards to the inhibition of N^ε-(carboxymethyl)lysine (CML) formation. PCs were found to significantly reduce CML (31.77%-87.56%), even at the lowest concentration, with the exception of ferulic acid (FA). The strongest inhibitory effect of FA (∼62%) appeared when concentration was increased to 1.0g/100g of flour. The available lysine losses (0.00%-90.51%) showed a significant correlation (0.853-0.990) with effectiveness of CML inhibition, except in the case of samples with FA. (+)-Catechin reduced CML levels the most, probably due to its structure-antioxidant activity relationship, its thermal stability (∼51% loss), and its reactivity with ε-lysine side chains (∼40.77% loss). Although the bread supplemented with PCs contained low levels of CML, this process may adversely affect bread flavor, reducing the formation of pyrazines (1.10%-80.77%).