Silvia Pastoriza

Contribution of melanoidins to the antioxidant capacity of the Spanish diet

Most foods included within the western diet are subjected to heat processing. During such treatment, the Maillard reaction takes place, generating brown polymers known as melanoidins. Melanoidins could have health beneficial properties such as chemopreventive, antimicrobial or antioxidant capacity. Here we have established the content of melanoidins in thermally processed foods consumed regularly in the Spanish diet (chocolate, sweet wine, balsamic vinegar, beer, bread, breakfast cereals and biscuits) and their antioxidant capacity by different in vitro methodologies (ABTS, FRAP, DPPH, ORAC, HOSC). The mean intake of melanoidins is 12.2g/person/day within the Spanish diet, bread, pilsner beer and biscuits being the foods that contributed most. The most antioxidant melanoidins were those from coffee, followed by balsamic vinegar and sweet wine. Finally, the average intake of antioxidant capacity coming from melanoidins was 717 μmol Trolox/day, melanoidins from coffee, biscuits, pilsner beer and chocolate being those which possessed more antioxidant capacity.

Nutritional and physicochemical characteristic of commercial Spanish citrus juices

Citrus juices are perceived as healthy foods by consumers due to their richness in antioxidant compounds. Despite the large number of papers about the antioxidant activity of citrus juices, less is known about the relationship with physicochemical properties. This paper shows that the overall antioxidant activity of citrus juices is underestimated with the standard methodologies, being up to 10-times higher with the GAR method (including an in vitro gastrointestinal digestion). 70% of the antioxidant activity was found in the soluble fraction and citrus juices contributed up to 12% of the overall antioxidant intake within the Spanish diet. Physicochemical parameters, such as colour, fluorescence, 5-hydroxymethylfurfural and furfural contents, were correlated with nutritional parameters in some samples. The intake of HMF was negligible from commercial citrus juices and was absent in freshly squeezed ones. Finally, a mathematical model is developed to classify juices depending on their nature or storage conditions.

Antioxidant balance after long-term consumption of standard diets including bread crust glycated compounds by adult rats

The objective of the present study was to evaluate the in vivo uptake of antioxidant capacity (AC) in rats fed on diets containing commonly consumed MRPs obtained from bread crust (BC) at long-term. Additionally we focused on understanding the effects of those compounds on the oxidative status of these animals. The global antioxidant response of the diets was measured. During 88 days, rats were fed control diet or diets containing BC or its soluble high molecular weight, soluble low molecular weight or insoluble fractions (BC, HMW, LMW and insoluble diets, respectively). In the final week, faeces from different dietary treatments were collected to determine the AC still retained in it and then calculate the uptake efficiency of AC. Animals were sacrificed and the liver and biceps brachii muscle were removed to investigate catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx) and reduced glutathione (GSH) levels. The addition of BC or its derivatives in the diet led to a significantly higher AC excreted with the faeces and to a lower uptake rate (around 90% in these groups vs. 98% in the control group). The muscle and liver showed different oxidative status after consumption of experimental diets. The muscle evidenced certain oxidative damage due to the BC consumption, more pronounced when the isolated fractions were ingested. However, the BC diet, but not the rest, induced a positive effect on the antioxidant defence in the liver, the key organ for xenobiotic metabolism, with increases in the CAT and GPx activities as well as the GSH stock (56, 20 and 14% with respect to the control group, respectively). The discordance found between the antioxidant status of muscle and antioxidant status of liver highlights the importance of considering several tissues to establish the effect of glycated compounds on the redox balance in an organism.

Effects of long-term consumption of standard diets including glucose-lysine model glycated compounds on the antioxidant status of adult rats

Our purpose was to evaluate the uptake of antioxidant capacity (AC) in rats fed long-term a diet containing commonly consumed Maillard reaction products (MRPs) from the glucose-lysine system. The effects on the oxidative status of liver, biceps brachii muscle and serum were also tested. The presence of model MRPs in the diet, especially melanoidins, led to a significantly higher intake (24.0μmolTrolox/day), faecal excretion (0.604μmolTrolox/day), and uptake (23.4μmolTrolox/day) of AC, although the uptake rate remained stable compared to the control group (97.5%). Consumption of the assayed MRPs did not affect the hepatic antioxidant defence while some positive modifications, like an increase in glutathione peroxidase, were detected in muscle (29%) and serum (400%). This pointed to an improved antioxidant capacity. Despite the interesting findings for these specific MRPs, attention must be paid to the overall consumption of MRPs from different sources in a conventional diet, due to their implications in the development/advance of many disorders.

Evolution of the Maillard Reaction in Glutamine or Arginine-Dextrinomaltose Model Systems

Enteral formulas are foods designed for medical uses to feed patients who are unable to eat normally. They are prepared by mixing proteins, amino acids, carbohydrates and fats and submitted to sterilization. During thermal treatment, the Maillard reaction takes place through the reaction of animo acids with reducing sugars. Thus, although glutamine and arginine are usually added to improve the nutritional value of enteral formulas, their final concentration may vary. Thus, in the present paper the early, intermediate, and advanced states of the Maillard reaction were studied in model systems by measuring loss of free amino acids through the decrease of fluorescence intensity with o-phtaldialdehyde (OPA), 5-Hydroximethylfurfural (HMF), furfural, glucosylisomaltol, fluorescence, and absorbance at 420 nm. The systems were prepared by mixing glutamine or arginine with dextrinomaltose (similar ingredients to those used in special enteral formula), and heated at 100 °C, 120 °C and 140 °C for 0 to 30 min. The recorded changes in the concentration of furanic compounds was only useful for longer heating times of high temperatures, while absorbance and fluorescence measurements were useful in all the assayed conditions. In addition, easiness and sensitivity of absorbance and fluorescence make them useful techniques that could be implemented as indicators for monitoring the manufacture of special enteral formulas. Glucosylisomaltol is a useful indicator to monitor the manufacture of glutamine-enriched enteral formulas.

Towards an improved Global Antioxidant Response method (GAR+): Physiological-resembling in vitro antioxidant capacity methods☆

Many methods have been developed to measure the antioxidant capacity of foods under non physiological-relevant conditions. In this study, three methods (TEACOH, GEACRED and TEACAAPH) are developed to measure antioxidant capacity at physiological pH, using indigo carmine as a redox dye. TEACOH and TEACAAPH determine foodstuffs scavenging capacity against hydroxyl (OH) and AAPH radicals, while the third method measures the global reducing capacity of the sample. The results obtained for commercial teas, commercial beverages containing tea as the main ingredient and different solid foods (spinach, onion, salami, etc.) were compared with well-established protocols. The new methods demonstrated good linearity-reproducibility, providing reliable data about the antioxidant capacity of foods under physiological-resembling conditions. The new methods were also useful for evaluating the antioxidant capacity of human plasma after acute intake of tea. The physiological-resembling conditions of these assays and the use of absorbance readings make them suitable for application by any laboratory.

Relationship between Glycation and Polyphenol Content and the Bioactivity of Selected Commercial Soy Milks

Soy milk is a health-promoting beverage of which consumption is steadily expanding. Different bioactivities have been associated with soy products such as antioxidant capacity, anti-inflammatory properties, or decrease of cancer development risk. These activities have been related to the presence of several compounds, including polyphenols and serine protease inhibitors, although factors influencing such activities have been scarcely studied. In this study, we have determined the antioxidant capacity (ABTS and FRAP methods measured with the global antioxidant response, GAR protocol), total phenolic content, serine protease inhibitory activity, and presence of heat damage indicators in commercial soy milks. Polyphenols were primarily responsible for the antioxidant capacity of soy milks, increasing their concentration after digestion. Glycation under heat treatment might be responsible for decreasing protease inhibitory activities in soy milks. The results obtained support a role for furosine, a known marker of Maillard reaction and glycation, as a potential indicator to monitor both thermal treatment and effects on protease inhibitory activities in soy milk. The contribution of soy milk consumption to the daily intake of antioxidants and serine protease inhibitory activities is discussed.

Towards an improved global antioxidant response method (GAR+): Physiological-resembling in vitro digestion-fermentation method

The antioxidant capacity of food influences its shelf life and human health. To determine this parameter, the corresponding antioxidant species must first be extracted. Current methods dont adequately address this issue since they rely on extractions with organic solvents or on in vitro digestion without a subsequent fermentation. We present an improved protocol to determine the global antioxidant response of foods (GAR+) including both in vitro digestion and fermentation. All samples should be fermented with the same fresh faecal inoculum in order to decrease variability. In addition, the use of a pool of faeces from healthy donors is strongly recommended to improve repeatability. Although most antioxidant capacity is achieved after digestion, in some foods fermentation plays a role. Thus, the GAR+ method provides reliable values of the antioxidant capacity of foods that are closer to their in vivo activity by including the effects of gut microbiota over non-digested nutrients.

Relationship between composition and bioactivity of persimmon and kiwifruit

Fruits are foods that contain plenty of vitamins, minerals and some bioactive phytochemicals like polyphenols. Thus, fruits may exert different functional properties on human health, some of which are directly related to their antioxidant capacity like cancer or atherosclerosis. Owing to globalization, consumers have a wide repertory of fruits throughout the year. Among them, tropical and subtropical fruits are steadily expanding, as well as the studies about them. In this sense, this timely review focused on the nutritional value and chemical composition of persimmon and kiwifruit, two tropical fruits with a protective role on different chronic diseases. Thus, this review focused mainly on the presence of bioactive compounds such as polyphenols, tannins, carotenoids, vitamin C and the different functional properties (i.e. antioxidant capacity, antithrombotic activity, decrease of plasmatic lipids, etc.) arising from the presence of such biologically active molecules. Finally, the effects of genotype and ripening stage on antioxidant capacity and the content of bioactive compounds in persimmon and kiwifruit are also discussed.

New Method To Estimate Total Polyphenol Excretion: Comparison of Fast Blue BB versus Folin–Ciocalteu Performance in Urine

Polyphenols are bioactive substances of vegetal origin with a significant impact on human health. The assessment of polyphenol intake and excretion is therefore important. The Folin-Ciocalteu (F-C) method is the reference assay to measure polyphenols in foods as well as their excretion in urine. However, many substances can influence the method, making it necessary to conduct a prior cleanup using solid-phase extraction (SPE) cartridges. In this paper, we demonstrate the use of the Fast Blue BB reagent (FBBB) as a new tool to measure the excretion of polyphenols in urine. Contrary to F-C, FBBB showed no interference in urine, negating the time-consuming and costly SPE cleanup. In addition, it showed excellent linearity (r2 = 0.9997), with a recovery of 96.4% and a precision of 1.86-2.11%. The FBBB method was validated to measure the excretion of polyphenols in spot urine samples from Spanish children, showing a good correlation between polyphenol intake and excretion.