Water-Soluble Coffee Melanoidins Inhibit Digestive Proteases.

Coffee is one of the most popular beverages around the world and its consumption contributes to the daily intake of dietary melanoidins. Despite the emerging physiological role of food melanoidins, their effect on digestive processes has not been studied so far. In this study, the activity of the gastrointestinal enzymes pepsin and trypsin was investigated in the presence of water-soluble coffee melanoidins. The gastric enzyme pepsin is only slightly affected, whereas the intestinal enzyme trypsin is severely inhibited by coffee melanoidins. The intestinal digestibility of casein was significantly inhibited by coffee melanoidins at a concentration achievable by regular coffee consumption. The inhibition of proteolytic enzymes by coffee melanoidins might decrease the nutritional value of dietary proteins.

Long-Lasting Impact of Sugar Intake on Neurotrophins and Neurotransmitters from Adolescence to Young Adulthood in Rat Frontal Cortex.

The detrimental impact of fructose, a widely used sweetener in industrial foods, was previously evidenced on various brain regions. Although adolescents are among the highest consumers of sweet foods, whether brain alterations induced by the sugar intake during this age persist until young adulthood or are rescued returning to a healthy diet remains largely unexplored. To shed light on this issue, just weaned rats were fed with a fructose-rich or control diet for 3 weeks. At the end of the treatment, fructose-fed rats underwent a control diet for a further 3 weeks until young adulthood phase and compared with animals that received from the beginning the healthy control diet. We focused on the consequences induced by the sugar on the main neurotrophins and neurotransmitters in the frontal cortex, as its maturation continues until late adolescence, thus being the last brain region to achieve a full maturity. We observed that fructose intake induces inflammation and oxidative stress, alteration of mitochondrial function, and changes of brain-derived neurotrophic factor (BDNF) and neurotrophin receptors, synaptic proteins, acetylcholine, dopamine, and glutamate levels, as well as increased formation of the glycation end-products Nε-carboxymethyllysine (CML) and Nε-carboxyethyllysine (CEL). Importantly, many of these alterations (BDNF, CML, CEL, acetylcholinesterase activity, dysregulation of neurotransmitters levels) persisted after switching to the control diet, thus pointing out to the adolescence as a critical phase, in which extreme attention should be devoted to limit an excessive consumption of sweet foods that can affect brain physiology also in the long term.

Tryptophan Supplementation Increases the Production of Microbial-Derived AhR Agonists in an In Vitro Simulator of Intestinal Microbial Ecosystem.

The aryl hydrocarbon receptor (AhR) plays an important role in intestinal homeostasis, and some microbial metabolites of tryptophan are known AhR agonists. In this study, we assessed the impact of tryptophan supplementation on the formation of tryptophan metabolites, AhR activation, and microbiota composition in the simulator of the human intestinal microbial ecosystem (SHIME). AhR activation, microbial composition, and tryptophan metabolites were compared during high tryptophan supplementation (4 g/L tryptophan), control, and wash-out periods. During tryptophan supplementation, the concentration of several tryptophan metabolites was increased compared to the control and wash-out period, but AhR activation by fermenter supernatant was significantly decreased. This was due to the higher levels of tryptophan, which was found to be an antagonist of AhR signaling. Tryptophan supplementation induced most microbial changes in the transverse colon including increased relative abundance of lactobacillus. We conclude that tryptophan supplementation leads to increased formation of AhR agonists in the colon.

Phytochemical-Rich Antioxidant Extracts of Vaccinium Vitis-idaea L. Leaves Inhibit the Formation of Toxic Maillard Reaction Products in Food Models.

Thermal treatment of proteinaceous foods generates heat-induced Maillard reaction substances including toxic advanced glycation end products (AGEs) and heterocyclic amines (HAs). It is known that plant phenolic compounds may influence Maillard reaction. This study investigated the impact of lingonberry leaf extracts on the formation of Nε -(carboxymethyl)lysine (CML) and Nε -(2-furoylmethyl)-L-lysine (furosine) in milk model system and HAs in meat-protein and meat model systems. In addition, lingonberry leaf extracts obtained by different solvents were characterized by radical scavenging, Folin-Ciocalteu assays and ultrahigh pressure liquid chromatography quadruple-time-of flight mass spectrometry (UPLC-qTOF-MS). Water extract (WE) stronger suppressed CML than furosine formation in milk model system: CML levels were reduced by nearly 40%. Moreover, quinic acid and catechin, which were abundant in WE, were effective in inhibiting CML and furosine formation. WE and acetone extract (AE) at 10 mg/mL significantly inhibited HAs formation in both model systems. However, higher suppressing effect on HAs formation showed AE, which had lower antioxidant capacity and total phenolic content values than WE. WE contained higher amounts of hydroxycinnamic acids, proanthocyanidins and flavonols, while AE was richer in flavan-3-ols and arbutin derivatives. It indicates that the composition of phenolics might be a major factor for explaining different effect of extracts from the same plant on HAs formation. In general, the results suggest that lingonberry leaves is a promising source of phytochemicals for inhibiting toxic Maillard reaction products and enriching foods with plant bioactive compounds. PRACTICAL APPLICATION: The increased consumption in processed foods has been linked with the increased risks of various diseases, while thermal food processing is required to develop flavor, insure safety, and extend shelf life. Therefore, developing effective technological means for inhibiting the formation of heat-induced toxic substances is an important task. This study showed a potential of lingonberry leaf extracts containing health beneficial phytochemicals to suppress the formation of toxic Maillard reaction products during heating of milk and meat.

Melanoidins from Coffee, Cocoa, and Bread Are Able to Scavenge α-Dicarbonyl Compounds under Simulated Physiological Conditions.

Free amino residues react with α-dicarbonyl compounds (DCs) contributing to the formation of advanced glycation end products (AGEs). Phenolic compounds can scavenge DCs, thus controlling the dietary carbonyl load. This study showed that high-molecular weight cocoa melanoidins (HMW-COM), HMW bread melanoidins (HMW-BM), and especially HMW coffee melanoidins (HMW-CM) are effective DC scavengers. HMW-CM (1 mg/mL) scavenged more than 40% DCs within 2 h under simulated physiological conditions, suggesting some physiological relevance. Partial acid hydrolysis of HMW-CM decreased the dicarbonyl trapping capacity, demonstrating that the ability to react with glyoxal, methylglyoxal (MGO), and diacetyl was mainly because of polyphenols bound to macromolecules. Caffeic acid (CA) and 3-caffeoylquinic acid showed a DC-scavenging kinetic profile similar to that of HMW-CM, while mass spectrometry data confirmed that hydroxyalkylation and aromatic substitution reactions led to the formation of a stable adduct between CA and MGO. These findings corroborated the idea that antioxidant-rich indigestible materials could limit carbonyl stress and AGE formation across the gastrointestinal tract.

Different temperatures select distinctive acetic acid bacteria species and promotes organic acids production during Kombucha tea fermentation.

Kombucha is a traditional beverage produced by tea fermentation, carried out by a symbiotic consortium of bacteria and yeasts. Acetic Acid Bacteria (AAB) usually dominate the bacterial community of Kombucha, driving the fermentative process. The consumption of this beverage was often associated to beneficial effects for the health, due to its antioxidant and detoxifying properties. We characterized bacterial populations of Kombucha tea fermented at 20 or 30 °C by using culture-dependent and -independent methods and monitored the concentration of gluconic and glucuronic acids, as well as of total polyphenols. We found significant differences in the microbiota at the two temperatures. Moreover, different species of Gluconacetobacter were selected, leading to a differential abundance of gluconic and glucuronic acids.

Impact of rapeseed press-cake on Maillard reaction in a cookie model system.

Rapeseed press-cake (RPC) is a byproduct of rapeseed oil production, rich in proteins and fiber. The aim of this study was to investigate the impact of cold pressed RPC, RPC fiber isolate and RPC alkaline extract on the formation of acrylamide and 5-hydroxymethylfufural (HMF) in cookies. Both compounds were influenced by the ingredients: the addition of RPC led to a significant dose-dependent increase of HMF in the cookies and to an increase of acrylamide up to 66.9%. On the contrary, acrylamide concentration was reduced down to 39.6% in presence of the alkaline extract and down to 4.4% in the presence of the fiber extract. The Michael addition of free amino acids to acrylamide was further investigated by high-resolution mass spectrometry (HRMS) revealing that cysteine was the preferred nucleophile for acrylamide elimination.

Encapsulation of ascorbic acid promotes the reduction of Maillard reaction products in UHT milk.

The presence of amino groups and carbonyls renders fortified milk with ascorbic acid particularly susceptible to the reduction of available lysine and to the formation of Maillard reaction products (MRPs), as Nε-(carboxyethyl)-l-lysine (CEL), Nε-(carboxymethyl)-l-lysine (CML), Amadori products (APs) and off-flavors. A novel approach was proposed to control the Maillard reaction (MR) in fortified milk: ascorbic acid was encapsulated in a lipid coating and the effects were tested after a lab scale UHT treatment. Encapsulation promoted a delayed release of ascorbic acid and a reduction in the formation of MRPs. Total lysine increased up to 45% in milk with encapsulated ascorbic acid, while reductions in CML, CEL and furosine ranged from 10% to 53% compared with control samples. The effects were also investigated towards the formation of amide-AGEs (advanced glycation end products) by high resolution mass spectrometry (HRMS) revealing that several mechanisms coincide with the MR in the presence of ascorbic acid.

Effect of olive mill wastewater phenol compounds on reactive carbonyl species and Maillard reaction end-products in ultrahigh-temperature-treated milk.

Thermal processing and Maillard reaction (MR) affect the nutritional and sensorial qualities of milk. In this paper an olive mill wastewater phenolic powder (OMW) was tested as a functional ingredient for inhibiting MR development in ultrahigh-temperature (UHT)-treated milk. OMW was added to milk at 0.1 and 0.05% w/v before UHT treatment, and the concentration of MR products was monitored to verify the effect of OMW phenols in controlling the MR. Results revealed that OMW is able to trap the reactive carbonyl species such as hydroxycarbonyls and dicarbonyls, which in turn led to the increase of Maillard-derived off-flavor development. The effect of OMW on the formation of Amadori products and N-ε-(carboxymethyl)-lysine (CML) showed that oxidative cleavage, C2-C6 cyclization, and the consequent reactive carbonyl species formation were also inhibited by OMW. Data indicated that OMW is a functional ingredient able to control the MR and to improve the nutritional and sensorial attributes of milk.