Mechanisms of action of coffee bioactive compounds - a key to unveil the coffee paradox.

The knowledge of the relationship between the chemical structure of food components with their mechanisms of action is crucial for the understanding of diet health benefits. This review relates the chemical variability present in coffee beverages with the mechanisms involved in key physiological events, supporting coffee as a polyvalent functional food. Coffee intake has been related with several health-promoting properties such as neuroprotective (caffeine, chlorogenic acids and melanoidins), anti-inflammatory (caffeine, chlorogenic acids, melanoidins, diterpenes), microbiota modulation (polysaccharides, melanoidins, chlorogenic acids), immunostimulatory (polysaccharides), antidiabetic (trigonelline, chlorogenic acids), antihypertensive (chlorogenic acids) and hypocholesterolemic (polysaccharides, chlorogenic acids, lipids). Nevertheless, caffeine and diterpenes are coffee components with ambivalent effects on health. Additionally, a large range of potentially harmful compounds, including acrylamide, hydroxymethylfurfural, furan, and advanced glycation end products, are formed during the roasting of coffee and are present in the beverages. However, coffee beverages are part of the daily human dietary healthy habits, configuring a coffee paradox.

The multi-targeted bioactive features of coffee compounds reinforce coffee as a functional food beverage.Polysaccharides and melanoidins positively modulate gut microbiota.Caffeine and phenolics are neuroprotective, anti-inflammatory, antidiabetic and antihypertensive.The balance between potential health and harmful compounds configures a coffee paradox.Harmful compounds are present in trace levels in coffee, not conferring toxicity.

Dwarf Kiwi (Actinidia arguta Miq.), a Source of Antioxidants for a Healthy and Sustainable Diet.

The feasibility of using dwarf kiwi fruits (Actinia arguta Miq.) as a healthy and sustainable food, compared to other types of commercial kiwi fruits, was evaluated in the present study. The overall antioxidant capacity of these fruits was assessed by either extraction-dependent methods (ABTS, ORAC) or the direct method called Quick, Easy, New, CHEap, Reproducible (QUENCHER) (DPPH, FRAP, Folin-Ciocalteu), applied for the first time to analyze kiwi fruits. With this methodology, all the molecules with antioxidant capacity are measured together in a single step, even those with high molecular weight or poor solubility in aqueous extraction systems, such as antioxidant dietary fiber. The effect of kiwi extracts on physiological and induced intracellular reactive oxygen species (ROS) production on IEC-6 cells was also analyzed, as well as total phenolic content (TPC) by Fast Blue BB, flavonols, hydroxycinnamic acids, and hydroxybenzoic acids. A. arguta fruits showed the highest values in all the antioxidant assays, being remarkably higher than the other kiwi species for Q-FRAP and Q-DPPH. Dwarf kiwi showed the highest potential in reducing physiological ROS and the highest values of TPC (54.57 mgGAE/g), being hydroxybenzoic acids the main phenolic family found (2.40 mgGAE/g). Therefore, dwarf kiwi fruits are a natural source of antioxidants compared to conventional kiwi fruits, being a sustainable and healthy alternative to diversify fruits in the diet.

Comparative Analysis of Selected Chemical Parameters of Coffea arabica, from Cascara to Silverskin.

Nowadays, there is an increased interest in coffee derivatives (green beans, roasted beans, and coffee by-products (Cascara and Silverskin)) due to their particular chemical composition. This study aimed to compare the content of dry matter, total fat, fatty acids, and fiber (ADF, NDF) of coffee by-products (Cascara and Silverskin) and coffee beans (green and roasted under different conditions). Coffee beans and their by-products were obtained from 100% C. arabica coffee cherries from Panama by dry process. The lowest concentrations of fat corresponded to Cascara 4.24 g·kg-1 and Silverskin 23.70 g·kg-1, respectively. The major fatty acids detected in all samples were palmitic, stearic, oleic, and linoleic acids, the latter two being essential fatty acids. LDA showed that 89.01% of the variability between beans and by-products was explained by lignoceric, myristic, behenic, tricosanoic, arachidic, and heneicosanoic acids. Silverskin appeared to be a good source of lignoceric, myristic, and behenic acids and had a higher concentration of dietary fiber (314.95 g·kg-1) than Cascara (160.03 g·kg-1). Coffee by-products (Silverskin and Cascara) are low-fat products enriched in dietary fiber. Their incorporation, after adjustment, into the global diet may contribute to nutrition security, the sustainability of the coffee sector, and human health.

In Vitro Bioaccessibility of Extractable Compounds from Tannat Grape Skin Possessing Health Promoting Properties with Potential to Reduce the Risk of Diabetes.

Diabetes pathogenesis encompasses oxidative stress, inflammation, insulin malfunctioning and partial or total insulin secretion impairment, which leads to a constant hyperglycemia. Polyphenols are known to possess bioactive properties, being Tannat grape skin a natural and sustainable source of these compounds. The present study aimed to find out the bioaccessibility of health-promoting molecules composing a multifunctional extract from Tannat grape skin obtained under hydro-alcoholic-acid conditions. The identification of phenolic compounds in the samples was performed by ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS). Subsequently, the samples were in vitro digested mimicking the human oral gastrointestinal conditions and the bioactivity of the digest (antioxidant, anti-inflammatory and modulation of glucose metabolism) was assessed. Effect on glucose metabolism was estimated by measuring carbohydrases activity and the functionality of glucose transporters of small intestine cells in presence and absence of the digested extract. Flavonoids, phenolic acids and phenolic alcohols were the major phenol compounds detected in the extract. The bioaccessible compounds protected the intestinal cells and macrophages against the induced formation of reactive oxygen species (ROS) and nitric oxide (NO). In addition, glucose transporters were inhibited by the digested extract. In conclusion, the bioaccessible compounds of the extract, including phenols, modulated key biochemical events involved in the pathogenesis of diabetes such as oxidative stress, inflammation and glucose absorption. The extract was effective under prevention with co-administration conditions supporting its potential for either reducing the risk or treating this disease.

Assessment of Healthy and Harmful Maillard Reaction Products in a Novel Coffee Cascara Beverage: Melanoidins and Acrylamide.

Our research aimed to evaluate the formation of Maillard reaction products in sun-dried coffee cascara and their impact on the safety and health promoting properties of a novel beverage called "Instant Cascara" (IC) derived from this coffee by-product. Maillard reaction products in sun-dried coffee cascara have never been reported. "Instant Cascara" (IC) extract was obtained by aqueous extraction and freeze-drying. Proteins, amino acids, lipids, fatty acid profile, sugars, fiber, minerals, and vitamins were analyzed for its nutritional characterization. Acrylamide and caffeine were used as chemical indicators of safety. Colored compounds, also called melanoidins, their stability under 40 °C and in light, and their in vitro antioxidant capacity were also studied. A safe instant beverage with antioxidant properties was obtained to which the following nutritional claims can be assigned: "low fat", "low sugar" "high fiber" and "source of potassium, magnesium and vitamin C". For the first time, cascara beverage color was attributed to the presence of antioxidant melanoidins (>10 kDa). IC is a potential sustainable alternative for instant coffee, with low caffeine and acrylamide levels and a healthy composition of nutrients and antioxidants.

Sensory Acceptance, Appetite Control and Gastrointestinal Tolerance of Yogurts Containing Coffee-Cascara Extract and Inulin.

The improvement of the nutritional quality of dairy foods has become a key strategy for reducing the risk of developing diet-related non-communicable diseases. In this context, we aimed to optimize the concentration of inulin in combination with 10 mg/mL of coffee-cascara extract in yogurt while considering their effect on appetite control, gastrointestinal wellbeing, and their effect on the sensory and technological properties of the product. For this purpose, we tested four coffee-cascara yogurt treatments in a blind cross-over nutritional trial with 45 healthy adults: a coffee-cascara yogurt without inulin (Y0) and coffee-cascara yogurts containing 3% (Y3), 7% (Y7), and 13% (Y13) of inulin. The ratings on sensory acceptance, satiety, gastrointestinal tolerance, and stool frequency were measured. Surveys were carried out digitally in each participant's cellphone. Yogurt pH, titratable acidity, syneresis, and instrumental texture were analyzed. Inulin addition increased the yogurt's firmness and consistency. Y13 achieved significantly higher overall acceptance, texture, and taste scores than Y0 (p < 0.05). Y3 presented similar gastrointestinal tolerance to Y0. However, 7% and 13% of inulin produced significant (p < 0.05) bloating and flatulence when compared to Y0. The appetite ratings were not significantly affected by the acute intake of the different yogurts. Overall, Y3 was identified as the formulation that maximized nutritional wellbeing, reaching a "source of fiber" nutritional claim, without compromising its technological and sensory properties.

An Assessment of the Bioactivity of Coffee Silverskin Melanoidins.

Melanoidins present in coffee silverskin, the only by-product of the roasting process, are formed via the Maillard reaction. The exact structure, biological properties, and mechanism of action of coffee silverskin melanoidins, remain unknown. This research work aimed to contribute to this novel knowledge. To achieve this goal, melanoidins were obtained from an aqueous extract of Arabica coffee silverskin (WO2013004873A1) and was isolated through ultrafiltration (>10 kDa). The isolation protocol was optimized and the chemical composition of the high molecular weight fraction (>10 kDa) was evaluated, by analyzing the content of protein, caffeine, chlorogenic acid, and the total dietary fiber. In addition, the structural analysis was performed by infrared spectroscopy. Antioxidant properties were studied in vitro and the fiber effect was studied in vivo, in healthy male Wistar rats. Melanoidins were administered to animals in the drinking water at a dose of 1 g/kg. At the fourth week of treatment, gastrointestinal motility was evaluated through non-invasive radiographic means. In conclusion, the isolation process was effective in obtaining a high molecular weight fraction, composed mainly of dietary fiber, including melanoidins, with in vitro antioxidant capacity and in vivo dietary fiber effects.