Bread crust melanoidins as potential prebiotic ingredients

The Maillard reactions: Pathways, consequences, and control

The century old Maillard reactions continue to draw the interest of researchers in the fields of Food Science and Technology, and Health and Medical Sciences. This chapter seeks to simplify and update this highly complicated, multifaceted topic. The simple nucleophilic attack of an amine onto a carbonyl group gives rise to a series of parallel and subsequent reactions, occurring simultaneously, resulting into a vast array of low and high mass compounds. Recent research has focused on: (1) the formation and transformation of α-dicarbonyl compounds, highly reactive intermediates which are essential in the development of the desired color and flavor of foods, but also lead to the production of the detrimental advanced glycation end products (AGEs); (2) elucidation of the structures of melanoidins in different foods and their beneficial effects on human health; and (3) harmful effects of AGEs on human health. Considering that MRs have both positive and negative consequences, their control to accentuate the former and to mitigate the latter, is also being conscientiously investigated with the use of modern techniques and technology.

Dietary advanced glycation end products (dAGEs): An insight between modern diet and health

Advanced glycation end products (AGEs) are formed by a series of chemical reactions of amino acids, peptides, proteins, and ketones at normal temperature or heated non-enzymatic conditions. A large amount of AGEs derived from Maillard Reaction (MR) during the process of food heat-processing. After oral intake, dietary AGEs are converted into biological AGEs through digestion and absorption, and accumulated in almost all organs. The safety and health risk of dietary AGEs have attracted wide attention. Increasing evidence have shown that uptake of dietary AGEs is closely related to the occurrence of many chronic diseases, such as diabetes, chronic kidney disease, osteoporosis, and Alzheimer's disease. This review summarized the most updated information of production, bio-transport in vivo, detection technologies, and physiological toxicity of dietary AGEs, and also discussed approaches to inhibit dietary AGEs generation. Impressively, the future opportunities and challenges on the detection, toxicity, and inhibition of dietary AGEs are raised.

The formation and structural characteristics of melanoidins from fermenting and distilled grains of Chinese liquor (baijiu)

Chinese liquor (baijiu) is a typical fermented food. In which production, melanoidins are formed in fermenting grains during low-temperature fermentation with long-term, and in distilled grains with high-temperature distillation for short-term. Here, the formation and structural characterization of melanoidins in these two distinct stages were first investigated through chemical composition analysis and spectroscopic identification. Our research showed that proteins and phenols continuously participate in melanoidin formation during fermentation and distillation processes. Distillation could produce melanoidins with larger amounts, darker colors, higher molecular weights, and more stable states than fermentation. The chemical composition including 10 carbohydrates, 17 amino acids, 5 free phenolic acids, and 7 bound phenolic acids was successfully identified in melanoidins. Ion chromatography was proposed to be an efficient method to investigate carbohydrates in melanoidins. Moreover, the potential impact of microorganisms on melanoidins was first revealed to be the possible utilization of glucose in melanoidins.

Probiotic Fermentation of Kelp Enzymatic Hydrolysate Promoted its Anti-Aging Activity in D-Galactose-Induced Aging Mice by Modulating Gut Microbiota

SCOPE

To investigate anti-aging effects of probiotic-fermented kelp enzymatic hydrolysate culture (KMF), probiotic-fermented kelp enzymatic hydrolysate supernatant (KMFS), and probiotic-fermented kelp enzymatic hydrolysate bacteria suspension (KMFP) in D-galactose-induced aging mice.

METHODS AND RESULTS

The study uses a probiotic-mixture of Lactobacillus reuteri, Pediococcus pentosaceus, and Lactobacillus acidophilus strains for kelp fermentation. KMF, KMFS, and KMFP prevent D-galactose-induced elevation of malondialdehyde levels in serum and brain tissue of aging mice, and they increase superoxide dismutase and catalase levels and total antioxidant capacity. Furthermore, they improve the cell structure of mouse brain, liver, and intestinal tissue. Compared with the model control group, the KMF, KMFS, and KMFP treatments regulate mRNA and protein levels of genes associated with aging, the concentrations of acetic acid, propionic acid, and butyric acid in the three treatment groups are more than 1.4-, 1.3-, and 1.2-fold increased, respectively. Furthermore, the treatments affect the gut microbiota community structures.

CONCLUSIONS

These results suggest that KMF, KMFS, and KMFP can modulate gut microbiota imbalances and positively affect aging-related genes to achieve anti-aging effects.

Physicochemical and Sensory Parameters of "Petipan" Enriched with Heme Iron and Andean Grain Flours

Enrichment is the addition of nutrients to a food that does not contain them naturally, which is conducted in a mandatory manner and in order to solve a nutritional deficiency in the population. Enriched petipan are products that contain heme iron. The objective of this research was to evaluate the physical, chemical, mechanical and sensory characteristics of petipan produced with Andean grain flours and heme iron concentrate. A completely randomized design (CRD) with five experimental treatments was used with different levels of heme iron. The results show the direct influence of the heme concentration level on the chromatic, mechanical and textural characteristics of petipan. As the heme concentrate increases, its mechanical properties are considerably affected, with there being a correlation between the color intensity and a considerable reduction in its porosity. Samples without heme iron (T0) and 1% heme iron concentrate (T1) present the best mechanical and sensory characteristics; however, the incorporation of heme concentrate directly influences its nutritional, textural, and mainly chromatic components.

Dough Rheological Behavior and Bread Quality as Affected by Addition of Soybean Flour in a Germinated Form

This study analyzes the possibility of using soybeans as an addition to the main ingredients used to make bread, with the aim of improving its quality characteristics. To maximize the nutritional profile of soybeans they were subjected to the germination and lyophilization process before being used in bread making. The addition levels of 5%, 10%, 15%, and 20% germinated soybean flour (GSF) on dough rheology and bread quality were used. From the rheology point of view, the GSF addition had the effect of decreasing the values of the creep and recovery parameters: J_Co, J_Cm, μ_Co, J_max, J_Ro, J_Rm, and J_r. At the same time, the rheological parameters λ_C and λ_R increased. The GSF addition did not affect dough homogeneity as may be seen from EFLM analysis. Regarding the quality of the bread, it may be concluded that a maximum of 15% GSF addition in wheat flour had a desirable effect on loaf volume, porosity, elasticity, and sensory properties of the bread. The bread samples with GSF additions showed a higher brightness and a less pronounced red and yellow tint. When the percentage of GSF in wheat flour increased, the value of the firmness parameter increased and the value of the gumminess, cohesiveness, and resilience parameters decreased. The addition of GSF had a desirable influence on the crumb structure of the bread samples. Thus, taking into account the results of the determinations outlined above, it can be stated that GSF addition in wheat flour leads to bread samples with good quality characteristics.

Beer and Microbiota: Pathways for a Positive and Healthy Interaction

Beer is one of the most consumed drinks worldwide. It contains numerous categories of antioxidants, phenolic products, traces of group B vitamins, minerals (selenium, silicon, potassium), soluble fibers and microorganisms. Low or moderate beer consumption, with or without alcohol, showed positive effects on health by stimulating the development of a healthy microbiota. In the present review we focused on four components responsible with interaction with gut microbiota: microorganisms, polyphenols, fiber and melanoidins, their presence in usual beers and on perspectives of development of fortified beers with enhanced effects on gut microbiota. Though microorganisms rarely escape pasteurization of beer, there are new unpasteurized types that might bring strains with probiotic effects. The polyphenols from beer are active on the gut microbiota stimulating its development, with consequent local anti-inflammatory and antioxidant effects. Their degradation products have prebiotic action and may combat intestinal dysbiosis. Beer contains dietary fiber such as non-starchy, non-digestible carbohydrates (β-glucans, arabinoxylans, mannose, fructose polymers, etc.) that relate with gut microbiota through fermentation, serving as a nutrient substrate. Another type of substances that are often considered close to fiber because they have an extremely low digestibility, melanoidins (melanosaccharides), give beer antioxidant and antibacterial properties. Though there are not many research studies in this area, the conclusion of this review is that beer seems a good candidate for a future functional food and that there are many pathways by which its ingredients can influence in a positive manner the human gut microbiota. Of course, there are many technological hinderances to overcome. However, designing functional beers fortified with fiber, antioxidants and probiotics, with a very low or no alcoholic content, will counteract the negative perception of beer consumption, will nullify the negative effects of alcohol, while simultaneously exerting a positive action on the gut microbiota.

Effects of Germinated Lentil Flour on Dough Rheological Behavior and Bread Quality

The present study analyzed the effects of germinated lentil flour (LGF) addition at different levels in wheat flour (2.5%, 5%, 7.5%, and 10%), on dough rheological behavior, dough microstructure, and bread quality. Creep-recovery tests showed that the dough samples with high levels of LGF addition presented a higher resistance to flow deformability of the dough. Dough microstructure as analyzed using EFLM showed an increase in the protein area (red color) and a decrease in the starch (green color) amount with the increased level of LGF addition in the wheat flour. It was found that the LGF addition led to the improvement of the porosity, specific volume, and elasticity of the bread samples. The breads with LGF addition were darker and had a slightly reddish and yellowish tint. The bread textural parameters highlighted significant (p < 0.05) higher values for firmness and gumminess and significant (p < 0.05) lower ones for cohesiveness and resilience for the bread with LGF addition when compared with the control. The bread samples with a 2.5% and 5% addition had a more dense structure of the crumb pores. Regarding sensory evaluation, the bread samples with LGF addition in the wheat flour were well appreciated by the consumers. The addition also was desirable due to the fact that it supplemented bread with a greater amount of protein and minerals due to the composition of lentil grains. Therefore, LGF could be successfully used as an ingredient for bread making in order to obtain bread with an improved quality.

Formation of melanoidins - Aldol reactions of heterocyclic and short-chain Maillard intermediates

In the course of the Maillard reaction, reducing sugars and amino compounds are converted to colorants, whose chemical structures are still mostly unknown. Active methylene compounds like norfuraneol that can initiate aldol condensation reactions are considered as key intermediates in this reaction. The aim of the present study was to characterize color formation of norfuraneol with different carbonyl compounds and to identify the underlying mechanisms of the reaction. Norfuraneol was incubated with methylglyoxal or diacetyl at elevated temperatures and the resulting reaction mixtures were analyzed by means of high-resolution mass spectrometry. It was demonstrated that aldol reactions lead to the formation of heterogeneous carbohydrate-based oligomers, which are likely to contribute to the elevated browning observed in the reaction mixtures. Furthermore, redox reactions were identified as another important part of the reaction, resulting in an increasing number of double bonds in the detected reaction products.

Dietary Melanoidins from Biscuits and Bread Crust Alter the Structure and Short-Chain Fatty Acid Production of Human Gut Microbiota

Melanoidins are the products of the Maillard reaction between carbonyl and amino groups of macromolecules and are readily formed in foods, especially during heat treatment. In this study we utilized the three-stage Human Gut Simulator system to assess the effect of providing melanoidins extracted from either biscuits or bread crust to the human gut microbiota. Addition of melanoidins to the growth medium led to statistically significant alterations in the microbial community composition, and it increased short-chain fatty acid and antioxidant production by the microbiota. The magnitude of these changes was much higher for cultures grown with biscuit melanoidins. Several lines of evidence indicate that such differences between these melanoidin sources might be due to the presence of lipid components in biscuit melanoidin structures. Because melanoidins are largely not degraded by human gastrointestinal enzymes, they provide an additional source of microbiota-accessible nutrients to our gut microbes.

Digestive properties of half-fin anchovy hydrolysates/glucose Maillard reaction products and modulation effects on intestinal microbiota

BACKGROUND

The consumption of dietary Maillard reaction products (MRPs) might lead to positive or negative effects on health. The digestibility of half-fin anchovy hydrolysates/glucose MRPs (HAHp(9.0)-G MRPs) was therefore determined. The intestinal microbiota modulation of HAHp(9.0)-G MRPs in mice was also evaluated after administration for 14 days (1 g kg^-1 •bodyweight).

RESULTS

Different levels of digestibility of MRPs of fructosamine and advanced glycation products of N^ε -carboxymethyllysine were detected in HAHp(9.0)-G MRPs during simulated gastrointestinal digestion. An increased relative proportion of soluble fluorescent melanoidins (SFMs) was observed during gastric digestion as compared to that in the original HAHp(9.0)-G MRPs, followed by decreases in SFMs in intestinal digestion. After feeding with HAHp(9.0)-G MRPs for 14 days, increased goblet cells were observed in the ileum regions of female and male mice. High-throughput 16S ribosomal RNA gene sequencing of fecal samples revealed that HAHp(9.0)-G MRPs administration increased the density of the phylum Bacteriodetes and reduced the density of the phylum Firmicutes in male mice. By comparison, a relatively higher density of members of the phylum Saccharibacteria was observed in female mice. A consistent increase in the abundance of Bacteroidales_S24-7_group_norank was found in female and male groups fed with HAHp(9.0)-G MRPs. Female and male mice treated with HAHp(9.0)-G MRPs also showed higher levels of propionic and butyric acids in feces than their corresponding controls.

CONCLUSION

Half-fin anchovy hydrolysates/glucose MRPs can be partly hydrolyzed in the simulated gastrointestinal digestion system. Treatment with HAHp(9.0)-G MRPs induced sex-related differences in bacterial abundance and diversity in mice; however, the up-regulation of anti-inflammatory activity was predicted in both female and male mice. © 2021 Society of Chemical Industry.

Antimicrobial properties and volatile profile of bread and biscuits melanoidins

This work gives novel information about the antimicrobial effect and volatiles of melanoidins isolated from Maria biscuit, common and soft bread. Melanoidins were isolated from scraped and sieved crusts (1 mm), after gluten digestion, 10 kDa ultrafiltration, and diafiltration. Finally, they were freeze-dried. Headspace solid-phase dynamic extraction coupled with a gas chromatograph with a mass spectrometer was used to determine the volatile profiles. The antimicrobial effect was evaluated against isolated strains of the most relevant food spoilage and pathogen microorganisms, together with some molds and yeasts. Melanoidins from common bread exhibited the most extensive antimicrobial activities and showed the most composite volatile profile. No undesirable compounds, such as furfural and 5-hydroxy-methyl-furfural, were found in any of the melanoidins studied. The obtained data pointed out that bakery melanoidins can exert effective food technological properties as natural antimicrobials that can improve shelf-life and security of foodstuffs, together with a possible contribution to food aroma.

Anti-aging effect of phlorizin on D-galactose-induced aging in mice through antioxidant and anti-inflammatory activity, prevention of apoptosis, and regulation of the gut microbiota

Aging is an inevitable and complicated process involving many physiological changes. Screening of natural biologically active anti-aging substances is a current research hotspot. Phlorizin (PZ), an important dihydrochalcone phytoconstituent, has been demonstrated to have antioxidant and anti-tumor effects. In this paper, different doses of PZ (20 and 40 mg/kg) were used to research the protective effect on D-galactose (D-gal)-induced aging mice. Following hematoxylin and eosin staining and by observing the hippocampus, we found that PZ alleviated the damage caused by D-gal in neuronal cells, while PZ enhanced the learning and memory abilities of aging mice in a radical eight-arm maze. In order to explain the reasons for these anti-aging effects, we tested the antioxidant enzyme activity and malonic dialdehyde concentration in mouse serum, liver, and brain tissue. The contents of proteins related to anti-inflammation and apoptosis in brain tissue were analyzed, and the gut microbiota was also analyzed. The results indicated that PZ improved antioxidant enzyme activity while significantly reducing the malonic dialdehyde content. Western blotting analysis suggested that PZ effectively alleviated neuro-apoptosis via regulating the expressions of Bax, Bcl-2, and caspase-3. PZ also exerted anti-inflammation effects by regulating the interleukin-1β/inhibitor of nuclear factor kappa B alpha/nuclear factor kappa-light-chain-enhancer of activated B-cells signaling pathways in brain tissues. Importantly, PZ improved the structure and diversity of the gut microbiota, and the microbiota-gut-brain axis may hold a key role in PZ-induced anti-aging effects. In conclusion, PZ can be used as a potential drug candidate to combat aging.

Effect of roasting conditions on cocoa bioactivity and gut microbiota modulation

Cocoa is a highly consumed food with beneficial effects on human health. Cocoa roasting has an important influence on its sensory and nutritional characteristics; therefore, roasting could also play a role in cocoa bioactivity. Thus, the aim of this paper is to unravel the effect of cocoa roasting conditions on its antioxidant capacity and modifications of gut microbiota after in vitro digestion-fermentation. HMF and furfural, chemical markers of non-enzymatic browning, were analyzed in unroasted and roasted cocoa powder at different temperatures, as well as different chocolates. The antioxidant capacity decreased with roasting, most probably due to the loss of phenolic compounds during heating. In the case of the evaluated chocolates, the antioxidant capacity was 2-3 times higher in the fermented fraction. On the other hand, HMF and furfural content increased during roasting due to increasing temperatures. Moreover, unroasted and roasted cocoa powder have different effects on gut microbial communities. Roasted cocoa favored butyrate production, whereas unroasted cocoa favored acetate and propionate production in a significant manner. In addition, unroasted and roasted cocoa produced significantly different gut microbial communities in terms of composition. Although many bacteria were affected, Veillonella and Faecalibacterium were some of the most discriminant ones; whereas the former is a propionate producer, the latter is a butyrate producer that has also been linked to positive effects on the inflammatory health of the gut and the immune system. Therefore, unroasted and roasted cocoa (regardless of the roasting temperature) promote different bacteria and a different SCFA production.

Barley Melanoidins: Key Dietary Compounds With Potential Health Benefits

This paper is a review of the potential health benefits of barley melanoidins. Food melanoidins are still rather understudied, despite their potential antioxidant, antimicrobial, and prebiotic properties. Free radicals are villainous substances in humans produced as metabolic byproducts and causing cancers and cardiovascular diseases, and the melanoidins alleviate the effects of these free radicals. Malt is produced from cereal grains such as barley, wheat, and maize, and barley is predominantly used in beer production. Beer (alcoholic and non-alcoholic) is a widely consumed beverage worldwide and a good source of dietary melanoidins, which enhance the beers' flavor, texture, and sensorial properties. Melanoidins, the final products of the Maillard reaction, are produced at different stages during the brewing process. Beer melanoidins protect the cells from oxidative damage of DNA. The high reducing capacity of melanoidins can induce hydroxyl radicals from H2O2 in the presence of ferric ion (Fe3+). Melanoidins inhibit lipid peroxidation during digestion due to their chelating metal property. However, lower digestibility of melanoidins leads to less availability to the organisms but is considered to function as dietary fiber that can be metabolized by the lower gut microbiota and possibly incur prebiotic properties. Melanoidins promote the growth of Lactobacilli and Bifidobacteria in the gastrointestinal tract, preventing the colonization of potential pathogens. Barley is already popular through beer production and increasingly as a functional food. Considering this economic and industrial importance, more research to explore the chemical properties of barley melanoidins and corresponding health benefits as barley is warranted.

Chemical Analysis, Toxicity Study, and Free-Radical Scavenging and Iron-Binding Assays Involving Coffee (Coffea arabica) Extracts

We aimed to analyze the chemical compositions in Arabica coffee bean extracts, assess the relevant antioxidant and iron-chelating activities in coffee extracts and instant coffee, and evaluate the toxicity in roasted coffee. Coffee beans were extracted using boiling, drip-filtered and espresso brewing methods. Certain phenolics were investigated including trigonelline, caffeic acid and their derivatives, gallic acid, epicatechin, chlorogenic acid (CGA) and their derivatives, p-coumaroylquinic acid, p-coumaroyl glucoside, the rutin and syringic acid that exist in green and roasted coffee extracts, along with dimethoxycinnamic acid, caffeoylarbutin and cymaroside that may be present in green coffee bean extracts. Different phytochemicals were also detected in all of the coffee extracts. Roasted coffee extracts and instant coffees exhibited free-radical scavenging properties in a dose-dependent manner, for which drip coffee was observed to be the most effective (p < 0.05). All coffee extracts, instant coffee varieties and CGA could effectively bind ferric ion in a concentration-dependent manner resulting in an iron-bound complex. Roasted coffee extracts were neither toxic to normal mononuclear cells nor breast cancer cells. The findings indicate that phenolics, particularly CGA, could effectively contribute to the iron-chelating and free-radical scavenging properties observed in coffee brews. Thus, coffee may possess high pharmacological value and could be utilized as a health beverage.

Inflammation Meets Metabolism: Roles for the Receptor for Advanced Glycation End Products Axis in Cardiovascular Disease

Fundamental modulation of energy metabolism in immune cells is increasingly being recognized for the ability to impart important changes in cellular properties. In homeostasis, cells of the innate immune system, such as monocytes, macrophages and dendritic cells (DCs), are enabled to respond rapidly to various forms of acute cellular and environmental stress, such as pathogens. In chronic stress milieus, these cells may undergo a re-programming, thereby triggering processes that may instigate tissue damage and failure of resolution. In settings of metabolic dysfunction, moieties such as excess sugars (glucose, fructose and sucrose) accumulate in the tissues and may form advanced glycation end products (AGEs), which are signaling ligands for the receptor for advanced glycation end products (RAGE). In addition, cellular accumulation of cholesterol species such as that occurring upon macrophage engulfment of dead/dying cells, presents these cells with a major challenge to metabolize/efflux excess cholesterol. RAGE contributes to reduced expression and activities of molecules mediating cholesterol efflux. This Review chronicles examples of the roles that sugars and cholesterol, via RAGE, play in immune cells in instigation of maladaptive cellular signaling and the mediation of chronic cellular stress. At this time, emerging roles for the ligand-RAGE axis in metabolism-mediated modulation of inflammatory signaling in immune cells are being unearthed and add to the growing body of factors underlying pathological immunometabolism.

Black garlic melanoidins prevent obesity, reduce serum LPS levels and modulate the gut microbiota composition in high-fat diet-induced obese C57BL/6J mice

The objective of this study is to assess the potential anti-obesity effects of black garlic melanoidins (MLDs) and gut microbiota changes in an animal model, hypothesizing that the effects of oral administration of MLDs can be partially mediated by the modulation of intestinal microbiota via inhibiting the formation of lipopolysaccharides (LPS) and promoting the production of short-chain fatty acids (SCFAs). The effects of MLDs in C57BL/6J mice with high-fat diet (HFD)-induced obesity were investigated for 12 weeks with low (50 mg kg-1 day-1), medium (100 mg kg-1 day-1) and high (200 mg kg-1 day-1) doses. The results indicated that oral administration of MLDs markedly reduced high fat diet-induced weight gain and white adipose tissue weights and reversed glucose tolerance, especially at high doses. Besides, MLDs could alleviate dyslipidaemia, significantly suppress hepatic lipid accumulation and steatosis and effectively ameliorate lipid metabolism. The plasma LPS reduced significantly and the SCFAs increased in a dose-dependent manner. The MLDs could down-regulate the expression of fatty acid synthase (FAS) and interleukin-6 (IL-6) and up-regulate the expression of adipose triacylglyceride lipase (ATGL) and hormone sensitive lipase (HSL) in adipose tissues and livers at mRNA levels. Moreover, after the oral administration of MLDs, the intestinal microbial environment improved in the sense that bacterial diversity and richness increased. Intervention with MLDs modified the gut microbiota in mice with HFD-induced obesity, increasing the number of SCFA-producing bacteria (Bacteroidaceae) and reducing opportunistic pathogens (Enterobacteriaceae and Desulfovibrionaceae). An increased abundance of other probiotics including Lactobacillaceae and Akkermansiaceae was also observed. In conclusion, MLDs could improve glucose tolerance, induce the production of SCFAs and inhibit the production of endotoxin LPS, most likely mediated by modulating the gut microbiota. Therefore, it seems that MLDs exhibit anti-obesity effects and might be used as potential agents against obesity.

A Systematic Review of Dietary Influences on Fecal Microbiota Composition and Function among Healthy Humans 1-20 Years of Age

Diet is a key modulator of fecal microbiota composition and function. However, the influence of diet on the microbiota from toddlerhood to adolescence and young adulthood is less well studied than for infancy and adulthood. We aimed to complete a qualitative systematic review of the impacts of diet on the fecal microbiota of healthy humans 1-20 y of age. English-language articles, published after 2008, indexed in the PubMed/MEDLINE, Cochrane, Web of Science, and Scopus databases were searched using keywords and Medical Subject Headings terms. Quality assessment of included studies was conducted using the Quality Criteria Checklist derived from the Nutrition Evidence Library of the Academy of Nutrition and Dietetics. A total of 973 articles were identified through database searching and 3 additional articles were included via cross-reference. Subsequent to de-duplication, 723 articles were screened by title and abstract, of which 709 were excluded based on inclusion criteria established a priori. The remaining 14 studies were independently screened by 2 reviewers for final inclusion. Included studies were published between 2010 and 2019 and included 8 comparative cross-sectional studies, 4 cross-sectional studies, 1 randomized crossover study, and 1 substudy of a randomized 2-period crossover trial. Associations of a diet rich in indigestible plant polysaccharides with Prevotella, or with an enterotype dominated by this genus, often comprised of the species Prevotella copri, were observed. In addition, associations of a high-fat and -sugar diet with Bacteroides, or with an enterotype dominated by this genus, were observed predominantly in comparative cross-sectional and cross-sectional studies spanning the ages of 1-15 y. This review identified a gap in the literature for ages 16-20 y. In addition, randomized controlled trials for dietary intervention are needed to move from association-based observations to causal relations between diet and microbiota composition and function. This systematic review was registered at www.crd.york.ac.uk/prospero as CRD42020129824.

Different Molecular Weight Black Garlic Melanoidins Alleviate High Fat Diet Induced Circadian Intestinal Microbes Dysbiosis

The purpose of this study is to explore the effects of different molecular weight black garlic melanoidins (MLDs) on high fat diet (HFD) induced dysrhythmia of intestinal microorganisms. The results showed that a HFD disturbed the periodic fluctuation of the gut microbiome and that oral gavage of low molecular weight melanoidin (LMM) or high molecular weight melanoidin (HMM) reversed these cyclical variations in part, which resulted in an increase in the number of bacteria producing short-chain fatty acids (SCFAs) and a decrease in the oscillation of inflammation-related bacteria within a specific time period over the course of 1 day. Moreover, structural analysis showed different structure characterizations of LMM and HMM, which are related to the differences in flora oscillation. Therefore, the data showed that LMM and HMM relieve the circadian rhythm disorder of intestinal microbiota induced by a HFD in mice, which supported the further study of MLDs as a new dietary assistant strategy to improve chronic diseases.

Interactions between free and bound antioxidants under different conditions in food systems

This review aimed to give comprehensive information about the interactions between free and bound antioxidants naturally found in different food matrices. In this context, firstly, the free and bound antioxidant terms are defined; their place in the daily diet, the path they follow in the body and their characteristics are explained. Factors affecting the interactions have been revealed as a result of the compilation of studies conducted until today, related to bound and free antioxidant interactions. Accordingly, it was observed that many factors such as reaction environment, concentration, pH, chemical structure, source and antioxidant/prooxidant nature of the compounds were effective on interactions. It has been emphasized that the interactions between free and bound antioxidants have a dynamic balance that can easily change under the influence of various factors, which in turn needs the interactions to be handled specifically for each case.

Cytotoxicity study of bakery product melanoidins on intestinal and endothelial cell lines

Melanoidins contribute to organoleptic properties of processed foods and exert benefits in health. The aim of this study was to isolate and characterize melanoidins from baked products (common bread, soft bread and biscuits), evaluate their cytotoxicity and determine their suitability as functional additives. Extraction yield, spectrophotometric characteristics, colorimetric properties, antioxidant capacity, and cytotoxicity of melanoidins were assessed. Among the studied products, soft bread had the highest extraction throughput. Melanoidins from biscuit showed the highest antioxidant capacity, closely followed by those of soft bread. Melanoidins did not exert cytotoxic effects on Caco-2 and HUVEC cells (viability was >80%). Nevertheless, incubation of HUVEC cells with melanoidins from common bread and biscuit slightly decreased viability, whereas gastrointestinal digestion of such melanoidins softened the decrease in cell viability. This study point to soft bread as a safe and efficient source of melanoidins, that could be potentially used in the future as functional ingredient.

Antioxidant Activity of Various Soluble Melanoidins Isolated from Black Garlic after Different Thermal Processing Steps

To gain insight into the antioxidant activity of various soluble melanoidins isolated from black garlic after different thermal processing steps, the antioxidant activity was evaluated. Black garlic was produced in a ripening chamber using a programmed stepwise heating schedule as follows: Step 1, 90°C and 100% (RH) for 34 h; Step 2, 60°C and 60% RH for 6 h; Step 3, 75°C and 70% RH for 48 h; Step 4, 70°C and 60% RH for 60 h; Step 5, 65°C and 50% RH for 192 h. The melanoidins isolated from black garlic after the different thermal processing steps were divided into different melanoidin fractions, i.e., melanoidins, pure melanoidin, bound melanoidin compounds (BMC). The antioxidant activity of the melanoidins bound to low molecular weight compounds (BMC fraction) was generally higher than those of the pure melanoidins. Notably, the antioxidant activity of various soluble melanoidins differed according to the thermal processing steps. The results may be useful in predicting the behavior of various soluble melanoidins during thermal processing of garlic.

Metabolic transit of dietary advanced glycation end-products - the case of NƐ-carboxymethyllysine

The Maillard reaction, also called glycation, is one of the major chemical reactions responsible for most yellow-to-brown colors and aromas in cooked foods. This reaction between reducing sugars and amino functions on proteins affects not only the flavor of food, but also leads to the formation of an heterogenous group of structurally-modified amino acids. Some of these, known as "advanced glycation end products" (AGEs), have been found in both foods and human biological fluids, tissues and organs. Except for those that are formed over long periods in vivo at 37 °C, AGEs in the body originate from the digestion and absorption of dietary sources. A high or chronic exposure to dietary AGEs (dAGEs) is suspected as potentially detrimental to human health and studies in the field of food safety have begun to focus their attention on the metabolic transit of dAGEs. This review presents some important findings in this field, with a focus on N^Ɛ-carboxymethyllysine, and presents the evidence for and against an association between intake of dAGEs and their presence in the body. New and promising avenues of research are described, and some future directions outlined.

Dietary Advanced Glycation Endproducts and the Gastrointestinal Tract

The prevalence of inflammatory bowel diseases (IBD) is increasing in the world. The introduction of the Western diet has been suggested as a potential explanation of increased prevalence. The Western diet includes highly processed food products, and often include thermal treatment. During thermal treatment, the Maillard reaction can occur, leading to the formation of dietary advanced glycation endproducts (dAGEs). In this review, different biological effects of dAGEs are discussed, including their digestion, absorption, formation, and degradation in the gastrointestinal tract, with an emphasis on their pro-inflammatory effects. In addition, potential mechanisms in the inflammatory effects of dAGEs are discussed. This review also specifically elaborates on the involvement of the effects of dAGEs in IBD and focuses on evidence regarding the involvement of dAGEs in the symptoms of IBD. Finally, knowledge gaps that still need to be filled are identified.

Contribution of melanoidins from heat-processed foods to the phenolic compound intake and antioxidant capacity of the Brazilian diet

In the present study we aimed at studying, determined and estimated the daily intake the contents of melanoidins and of their phenolic-bound compounds, and the antioxidant capacity of thermally processed foods regularly consumed in the Brazilian diet. Among twenty-three heat-processed Brazilian food samples, melanoidins contents ranged from 1.6 (dulce de leche) to 21.4 g/100 g (soluble coffee). Considering melanosaccharides, roasted maté showed the highest content of bound phenolics (6415.1 µg/100 mg), whereas whole grain breakfast cereals (229.3 µg/100 mg) stood out among melanoproteins. The antioxidant capacity of melanoidins was strongly correlated with their bound phenolic compounds (r > 0.8522, p < 0.0001). We estimated that up to 10.7 g of melanoidins are daily consumed by the Brazilian population, with beer the major contributor (44%), followed by cereal products (36%) and coffee (17%). Brazilians ingest up to 26.0 mg of bound phenolics a day, mainly from coffee (75%) and beer (13%) melanoidins. Therefore, the estimated intake of phenolic compounds by Brazilians is underestimated by up to 7%. Moreover, melanoidins contribute to up to 21% of the Brazilian dietary antioxidant capacity.

Formation, nutritional value, and enhancement of characteristic components in black garlic: A review for maximizing the goodness to humans

Black garlic (BG) is essentially a processed food and obtained through the transformation of fresh garlic (FG) (Allium sativum L.) via a range of chemical reactions (including the Maillard reaction) and microbial fermentation. This review provides the up-to-date knowledge of the dynamic and complicated changes in major components during the conversion of FG to BG, including moisture, lipids, carbohydrates (such as sugars), proteins, organic acids, organic sulfur compounds, alkaloids, polyphenols, melanoidins, 5-hydroxymethylfurfural, vitamins, minerals, enzymes, and garlic endophytes. The obtained evidence confirms that BG has several advantages over FG in certain product attributes and biological properties (especially antioxidant activity), and the factors affecting the quality of BG include the type and characteristics of FG and processing technologies and methods (especially pretreatments, and processing temperature and humidity). The interactions among garlic components, and between garlic nutrients and microbes, as well as the interplay between pretreatment and main manufacturing process, all determine the sensory and nutritional qualities of BG. Before BG is marketed as a novel snack or functional food, more research is required to fill the knowledge gaps related to quantitative monitoring of the changes in metabolites (especially those taste-active and/or biological-active substances) during BG manufacturing to maximize BG's antioxidant, anticancer, antiobesity, anti-inflammatory, immunostimulatory, anti-allergic, hepatoprotective, cardioprotective and oxidative stress-/hangover syndrome-reducing functions, and beneficial effects on memory/nervous systems. Assessments of the quality, efficacy, and safety of BG should be performed considering the impacts of BG production conditions, postproduction handling, and intake methods.

Functional and biological properties of Maillard conjugates and their potential application in medical and food: A review

Protein and peptides are usually sensitive to environmental stresses, such as pH changes, high temperature, ionic strength, and digestive enzymes amongst other, which limit their food and medicinal applications. Maillard reaction (also called Maillard conjugation or glycation) occurs naturally without the addition of chemical agents and has been vastly applied to boost protein/peptide/amino acid functionalities and biological properties. Protein/peptide-saccharide conjugates are currently used as emulsifiers, antioxidants, antimicrobials, gelling agents, and anti-browning compounds in food model systems and products. The conjugates also possess the excellent stabilizing ability as a potent delivery system to enhance the stability and bioaccessibility of many bioactive compounds. Carbonyl scavengers such as polyphenols are able to significantly inhibit the formation of advanced glycation end products without a significant effect on early Maillard reaction products (MRPs) and melanoidins, which are currently applied as functional ingredients. This review paper highlights the technological functionality and biological properties of glycoconjugates in food model systems and products. Recent applications of MRPs in medical sciences are also presented.

Gut Microbiota Modulation by Dietary Barley Malt Melanoidins

Melanoidins are the final Maillard reaction products (protein–carbohydrate complexes) produced in food by prolonged and intense heating. We assessed the impact of the consumption of melanoidins from barley malts on gut microbiota. Seventy-five mice were assigned into five groups, where the control group consumed a non-melanoidin malt diet, and other groups received melanoidin-rich malts in increments of 25% up to 100% melanoidin malts. Feces were sampled at days 0, 1, 2, 3, 7, 14, and 21 and the microbiota was determined using V4 bacterial 16S rRNA amplicon sequencing and short-chain fatty acids (SCFA) by gas chromatography. Increased melanoidins was found to result in significantly divergent gut microbiota profiles and supported sustained SCFA production. The relative abundance of Dorea, Oscillibacter, and Alisitpes were decreased, while Lactobacillus, Parasutterella, Akkermansia, Bifidobacterium, and Barnesiella increased. Bifidobacterium spp. and Akkermansia spp. were significantly increased in mice consuming the highest melanoidin amounts, suggesting remarkable prebiotic potential.

Potential effects of rapeseed peptide Maillard reaction products on aging-related disorder attenuation and gut microbiota modulation in d-galactose induced aging mice

As a good flavor enhancer, rapeseed peptide Maillard reaction products (MRPs) were developed, and the effects of MRPs on d-galactose induced aging Kunming mice were investigated for 6 weeks with low (200 mg kg-1 day-1), medium (400 mg kg-1 day-1) and high (800 mg kg-1 day-1) doses. Compared with the natural aging group and d-galactose induced aging mice, the mice with MRP administration showed increases in body weight gain, food intake, organ indexes, feces color and urine fluorescence intensity. MRP intake significantly decreased the MDA content and elevated the activities of CAT, SOD and GSH-Px, and T-AOC in the serum and tissues of the liver, kidney and brain. Additionally, AChE activity was decreased in the brain, while Na+-K+ ATPase and Ca2+-Mg2+ ATPase activity increased in a dose-dependent manner, and decreasing levels of IL-1β, IL-6 and TNF-α were observed in the liver and kidney. Histopathological analysis suggested an attenuation of inflammatory cell infiltration in the liver and kidney without cell necrosis. High-throughput sequencing results revealed that the ratio of Firmicutes to Bacteroidetes increased in MRP groups, and the pathogenic bacteria were significantly inhibited, while some beneficial bacteria were significantly increased in the intestine. Overall, our results indicated that MRP consumption might have potential beneficial effects on postponing the aging process via reducing the oxidative stress and gut microflora modulation.

Melanoidins from Chinese Distilled Spent Grain: Content, Preliminary Structure, Antioxidant, and ACE-Inhibitory Activities In Vitro

Distilled spent grain (DSG), as the major by-product of baijiu making, contains melanoidins generated via the Maillard reaction. In this study, four melanoidin fractions (RF1‒RF4) were isolated successively from dried DSG (DDSG) using sodium hydroxide solution and water as extractants, and the content, preliminary structure, and ACE-inhibitory activities in vitro of melanoidins were first investigated. The antioxidant activity was also evaluated. The results indicated that the total content of melanoidins was 268.60 mg/g DDSG dry weight (dw) using a model system of glucose and serine as standard, and RF4 showed the highest content of melanoidins (174.30 mg/g DDSG dw). Functional groups like C=O, N‒H, C‒N, O‒H, C‒H, C‒O, C-C, and ‒C‒CO‒C‒ were present in the structure of melanoidins from RF4, as determined by Fourier transform infrared (FT-IR) assay. The highest antioxidant activities, as assessed by 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS•+), ferric-reducing antioxidant power (FRAP), and 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) assays, and the highest angiotensin-converting enzyme (ACE) inhibitory activity (95.92% at 2 mg RF4/mL) were also exhibited by RF4. The RF4 was further fractionated by ultrafiltration based on molecular weight (MW). The more than 100 kDa melanoidins (RF4-6) exhibited the highest yield and antioxidant activity. The 3‒10 kDa melanoidins (RF4-2) were more efficient in ACE-inhibitory activity. Our study could raise awareness of the DDSG as a value-added resource.

Food processing, gut microbiota and the globesity problem

In the context of diseases of affluence, western diets have in the past years mainly been studied on their fat and sugar content and lack of dietary fiber. Yet, the more general aspect of food processing has recently sparked scientific interest as well. In addition, the gut microbiota have been put forward as an important link between diet, obesity and non-communicable diseases (NCD). Western dietary patterns, containing large amounts of processed foods might create an imbalance in the gut system by affecting gut bacteria and their metabolism. Here we discuss what has been already published regarding the relationship between several recently researched features of processed foods and the etiology of obesity and NCD. The addressed features concern micronutrient and energy density, several types of food additives and the generation of advanced glycation end products by thermal treatment during food processing. Overall, literature indicates that all discussed aspects can be linked to western ailments and that they can have a potential negative impact on human microbiota. Therefore, we propose that the thesis that a distressed gut microbiota is a mechanism that might explain how food processing features could harm human health is gaining empirical evidence. Future research will need to address the question whether the alteration of the gut microbiota is a direct or an indirect (via the host) effect. These conclusions are important assets in the fight against the continuing worldwide upsurge of obesity and NCD.

The role of chronic kidney disease-associated dysbiosis in cardiovascular disease

IMPACT STATEMENT

Negative alterations, or dysbiosis, in the intestinal microbial community balance in response to chronic kidney disease is emerging as a substantial and important factor in inducing and exacerbating multiple comorbid conditions. Patients with renal insufficiency experience a substantial increase in cardiovascular risk, and recent evidence is shedding light on the close interaction between microbiome dysbiosis and increased cardiovascular events in this population. Previous association and recent causality studies utilizing experimental animal models have enriched our understanding and confirmed the impact of microbial community imbalance on cardiac health in both the general population and in patients with renal impairment.

Digestibility of glycated milk proteins and the peptidomics of their in vitro digests

BACKGROUND

Milk proteins are widely used in food production and are often glycated by reducing sugar. Although many studies have reported the digestibility of glycated milk protein, most have focused on measuring degree of hydrolysis (DH), showing sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) image of digests. Detailed information on the changes in peptide composition of digests has seldom been revealed. Therefore, in addition to measuring the DH and showing the SGS-PAGE images of digests, we also analyzed the peptidomics in digests using liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) and Mascot database in this work to further reveal the influence of glycation on protein nutrition.

RESULTS

Compared with β-lactoglobulin and bovine serum albumin (BSA), DH of β-casein was suppressed to a lesser extent by glycation in both gastric and intestinal stages. Aggregates of glycated BSA were less sensitive to the action of digestive enzymes throughout gastrointestinal digestion according to SDS-PAGE images. Changes in the peptide composition of digests induced by glycation were distinctly displayed, showing both absence of peptides and occurrence of new peptides, based on the results obtained from LC-ESI-MS/MS.

CONCLUSIONS

Glycation can greatly change the peptide composition in digests of milk protein. The nutritional impact of the change in the peptide composition requires further investigation, and the impact of MRPs in unabsorbed digests on the gut flora should be an interesting field for further studies. © 2018 Society of Chemical Industry.

Potential effects of dietary Maillard reaction products derived from 1 to 3 kDa soybean peptides on the aging ICR mice

Effects of Maillard reaction products derived from 1 to 3 kDa soybean peptides (MRPF3) on aging ICR mice were investigated. Seven animal groups were established for 5 weeks, including one normal group and six D-galactose (1000 mg kg-1/day) treated groups. Aging control was D-galactose + saline solution, and positive controls were D-galactose + ascorbic acid (Vc) (400 mg kg-1/day) and oligofructose (400 mg kg-1/day), respectively, while the test groups are D-galactose + high (800 mg kg-1/day), medium (400 mg kg-1/day) and low (200 mg kg-1/day) doses of MRPF3. Compared with the aging controls, food intake, body weights and organ indexes returned to normal after feeding with MRPF3, and the color of feces as well as the fluorescence intensity of urine increased. The content of malondialdehyde (MDA) in the liver significantly decreased with the intake of MRPF3, and the activities of SOD and GSH-Px and the total antioxidant capacity of serum significantly increased. The abundance ratio of Bacteroidetes and Firmicutes significantly decreased in MRPF3 groups, and the abundance of Lactobacillus significantly increased, while potentially pathogenic bacteria such as Porphyromonadaceae significantly decreased. Our results showed that MRPF3 might offer a potent retardation potential for aging.

Dietary Advanced Glycation End Products: Digestion, Metabolism and Modulation of Gut Microbial Ecology

The formation of advanced glycation end products (AGEs) in foods is accelerated with heat treatment, particularly within foods that are cooked at high temperatures for long periods of time using dry heat. The modern processed diet is replete with AGEs, and excessive AGE consumption is thought to be associated with a number of negative health effects. Many dietary AGEs have high molecular weight and are not absorbed in the intestine, and instead pass through to the colon, where they are available for metabolism by the colonic bacteria. Recent studies have been conducted to explore the effects of AGEs on the composition of the gut microbiota as well as the production of beneficial microbial metabolites, in particular, short-chain fatty acids. However, there is conflicting evidence regarding the impact of dietary AGEs on gut microbiota reshaping, which may be due, in part, to the formation of alternate compounds during the thermal treatment of foods. This review summarises the current evidence regarding dietary sources of AGEs, their gastrointestinal absorption and role in gut microbiota reshaping, provides a brief overview of the health implications of dietary AGEs and highlights knowledge gaps and avenues for future study.

Effects of Maillard Reaction Products on Sensory and Nutritional Qualities of the Traditional French Baguette

The goals of this study were to evaluate the effect of baking time on the Maillard reaction products (MRPs) generated in the crust of the traditional French baguette and to estimate their impact on its sensory characteristics, its acrylamide content, and its bifidogenic effect. Melanoidins, volatile compounds, and acrylamide were evaluated in the crust of traditional French baguettes baked between 12 and 22 min at 225 °C. The increase in melanoidins was positively correlated to the baking time, while volatile compounds only increased until 18 min. The acrylamide content was estimated to be below 18 μg/kg, which confirms the findings of EFSA that bread is not a main contributor to dietary acrylamide. A descriptive sensory analysis showed that the baking time positively affected the sensory quality of the crust. The consumer test revealed the same trend and the panelists favorably judged the well-baked baguettes based on a better crust flavor and crispness. The bifidogenic effect of the crust and the crumb from the baguettes baked 22 min was evaluated on the in vitro growth of Bifidobacterium adolescentis. The results demonstrated that the crumb and the crust had exactly the same bifidogenic impact, therefore not caused by melanoidins.

PRACTICAL APPLICATION

The consumption of bread in France has decreased since 2007, although bread is considered by French people as "healthy" and essential to maintain a balanced diet. The current study evaluated the global qualities of the French baguette in order to highlight its high sensory quality and its beneficial effect by inducing a possible growth of bifidobacteria, even in well-baked baguettes. These findings allow the French bakery industry to develop an argument to promote its technical know-how and to help consumers choose healthier and tastier bread. Moreover, this study provided some recommendations of baking processes to maintain a high sensory quality of the French baguette and limit the formation of undesirable compounds, such as acrylamide, in the crust.

Straw Wine Melanoidins as Potential Multifunctional Agents: Insight into Antioxidant, Antibacterial, and Angiotensin-I-Converting Enzyme Inhibition Effects

Numerous studies provide robust evidence for a protective effect of red wine against many diseases. This bioactivity has been mainly associated with phenolic fractions of wines. However, the health effects of melanoidins in red sweet wines has been ignored. The goal of the present work was to unravel the antioxidant, antimicrobial, and angiotensin-I-converting enzyme (ACE) inhibitory properties of straw sweet wine melanoidins. Results demonstrated that melanoidins have a potential antioxidant activity, determined by 2,2-Diphenyl-1-picrylhydrazyl (DPPH) and Ferric reducing antioxidant power (FRAP) assays. The antimicrobial activity of melanoidins was also tested against Listeria monocytogenes, Salmonella Enteritidis, and Escherichia coli. Minimum inhibitory concentration (MIC) of isolated melanoidins against three bacterial strains ranged from 5 mg mL⁻¹ to 10 mg mL⁻¹. Finally, the ACE inhibitory effect of isolated melanoidins was evaluated, as it is linked with antihypertensive activity. Results showed that they have ACE-inhibitory activity ranging from 58.2 ± 5.4% to 75.3 ± 6.4% at a concentration level of 2 mg mL⁻¹. Furthermore, the chemical properties of isolated melanoidins were determined. Results demonstrated that the skeleton of straw wine melanoidins is mainly composed of carbohydrates, and bear significant numbers of phenolic compounds that may play critical roles in their functional properties. Overall, this study describing the chemical composition and functional properties of melanoidin fractions isolated from a straw wine highlights that they can be exploited as functional agents for multiple purposes. Finally, melanoidins are an unexplored source of bioactive molecules in straw wines except from polyphenols that contribute to the health effects.