Luis Cisneros-Zevallos

Correlations of Antioxidant Activity against Phenolic Content Revisited: A New Approach in Data Analysis for Food and Medicinal Plants

This study presents a new approach to analyze data correlating total antioxidant activity and total phenolic compounds in foods. The correlation of both variables is a common practice found in the literature. The purpose of these correlations is to determine the contribution of phenolics to the total antioxidant activity of foods. When low R(2) values are obtained, the general conclusion is that other compounds have a higher relevance than phenolics in the total antioxidant activity of the samples. However, these correlations do not consider differences in the phenolic profiles that can be qualitatively (type of phenolics present) and quantitatively (the relative amounts or proportions of phenolics present) among the samples under investigation. The new approach to analyze these simple correlations presented herein takes into consideration the phenolic profiles and provides information on the effectiveness of phenolics present in the samples to neutralize free radicals. Data obtained from carrots stored under conditions of air and hyperoxia (superatmospheric oxygen) are used to exemplify how to apply this new approach.

Antioxidant capacity, anthocyanins and total phenolics in purple-and red-fleshed potato (Solanum tuberosum L.) genotypes

Purple- and red-fleshed potatoes (Solanum tuberosum L.) were evaluated for their total anthocyanin (ACY), total phenolic (PHEN), and antioxidant capacity. The ACY and PHEN compounds were distributed throughout the tubers; however, a higher concentration was found at the stem-end than the bud-end. Although ACY and PHEN concentrations in potato peel were 0.9-to 1.6-fold higher than in potato flesh, overall contribution of the peel to ACY and PHEN contents of a potato slice was ∼20%. These observations differ from the widespread idea that phytonutrients are mostly accumulated in the peel of tubers. The ACY and PHEN contents of different purple- and red-fleshed potato genotypes ranged from 11 to 174 mg cyanidin-3-glucoside/100 g fresh weight and from 76 to 181 mg chlorogenic acid/100 g fresh weight, respectively, and were genotype and location dependent. High positive correlations between antioxidant capacity and ACY and PHEN suggest that these compounds are mainly responsible for the antioxidant capacity. These results provide useful and important information for potato breeders and researchers in order to increase the antioxidant capacity and functional value of purple- and red-fleshed potatoes for the food and nutraceutical industries.ResumenPapas (Solanum tuberosum L.) de pulpa morada y roja, se evaluaron para determinar su contenido total de antocianina (ACY), compuestos fenólicos totales (PHEN) y capacidad antioxidante. Los compuestos ACY y PHEN estuvieron distribuidos por todo el tubérculo; sin embargo, se encontró una mayor concentración en el extremo cerca del tallo que en el extremo distal. Aunque las concentraciones en la piel del tubérculo fueron de 0.9 a 1.6 veces más que en la pulpa, el aporte total del ACY y PHEN de la piel de una rodaja de papa fue de aproximadamente 20%. Estas observaciones difieren de la idea generalizada de que los fitonutrientes se acumulan mayormente en la piel de los tubérculos. El contenido de ACY y PHEN de los tubérculos de los diferentes genotipo de papa de pulpa morada y roja estuvo entre los limites de 11 a 174 mg de cianidina-3-glucósido/100 g de peso fresco y de 76 a 180 mg de ácido clorogénico/100 g de peso fresco respectivamente dependiendo del lugar y genotipo. La alta correlación positiva entre la capacidad antioxidante y ACY y PHEN sugiere que estos compuestos son principalmente responsables de la capacidad antioxidante. Estos resultados proporcionan información muy importante y útil a los mejoradores e investigadores para incrementar la capacidad antioxidante y el valor funcional de las papas de pulpa morada y roja para el consumo y las industrias nutraceúticas.

Plants as biofactories: physiological role of reactive oxygen species on the accumulation of phenolic antioxidants in carrot tissue under wounding and hyperoxia stress.

Plants subjected to postharvest abiotic stresses synthesize secondary metabolites with health-promoting properties. Here, we report the potential use of carrots (Daucus carota) as biofactories of caffeoylquinic acids when subjected to wounding and hyperoxia stresses. Wounding stress induced an increase of ∼287% in total phenolic content (PC) in carrots stored for 48 h at 20 °C. This increase was higher (∼349%) in the wounded tissue treated with hyperoxia stress. To further understand the physiological role of reactive oxygen species (ROS) as a signaling molecule for the stress-induced accumulation of phenolics in carrots, the respiration rate as well as the enzymatic activities of NADPH oxidase, superoxide dismutase, ascorbate peroxidase, and catalase were evaluated. Likewise, shredded carrots were treated with diphenyleneiodonium chloride solution to block NADPH oxidase ROS productions, and the phenylalanine ammonia lyase activity and total PC were evaluated. Results demonstrated that ROS play a key role as a signaling molecule for the stress-induced accumulation of PC in carrots.

Application of casein-lipid edible film emulsions to reduce white blush on minimally processed carrots

White blush on the surface of peeled carrots is a major cosmetic disadvantage in marketing this lightly processed, ready-to-eat product. The loss of quality is exacerbated by surface dehydration. To maintain good appearance, edible coatings consisting of emulsions incorporating caseinates with beeswax, stearic acid or acetylated monoglyceride were tested. All except the latter increased water vapor resistance. Sodium caseinate-stearic acid was particularly effective in ameliorating the disorder.

Environmental conditions influence the content and yield of anthocyanins and total phenolics in purple- and red-flesh potatoes during tuber development

Changes in content and yield of anthocyanins (ACY) and total phenolics (PHEN) during development of purple- and red-flesh potato (Solanum tuberosum L.) were studied in cultivars grown in Texas and Colorado. In both locations, the ACY and PHEN content (mg/100 g tissue) decreased with tuber growth and maturity, while tuber weight (kg), total yield (Ton ha-1) and compound yields (kg ha-1) increased. Longer days and cooler temperatures in Colorado favored about a 2.5- and 1.4-times higher ACY and PHEN content, respectively, than in Texas-grown tubers. Harvesting potatoes at later maturity stages maximized compound yields while minimizing the glycoalkaloid content. This information can be useful to potato breeders and producers in selecting appropriate growing conditions for the enhancement of natural colorant and antioxidant yields in purple- and red-flesh potatoes for the nutraceutical and food industry.ResumenSe estudiaron los cambios en el contenido y rendimiento de antocianinas (ACY) y fenolicos totales (PHEN) en cultivares de papa (Solanum tuberosum L.) de pulpa morada y roja, durante su desarrollo en Texas y Colorado. En ambas localidades, el contenido de ACY y PHEN (mg/100 g de tejido) disminuyó a medida que el tubérculo desarrolló y maduró, mientras que el peso de tubérculos (kg), el rendimiento total (Ton ha-1) y el rendimiento de compuestos fenolicos (kg ha-1) aumentaron. Los días más largos y temperaturas frías en Colorado favorecieron el contenido de ACY y PHEN en los tubérculos cosechados en 2.5 y 1.4 veces respectivamente, que aquellos obtenidos en Texas. La cosecha de tubérculos en periodos tardíos de madurez maximizó los rendimientos de compuestos fenolicos, mientras que el contenido de glicoalcaloides se minimizó. Esta información puede ser útil para mejoradores y productores de papa, con el fin de seleccionar las condiciones apropiadas de cultivo que aumenten el rendimiento de colorantes y antioxidantes, en papas de pulpa morada y roja, para su utilización en las industrias nutracéuticas y de alimentes.

The Folin–Ciocalteu assay revisited: improvement of its specificity for total phenolic content determination

This study presents a review of the Folin–Ciocalteu (F–C) assay for total phenolic content (TPC) determinations and describes different approaches to improve its specificity. Phenolics are regarded as the molecules with the highest potential to neutralize free radicals. Therefore, their quantification is a common practice in different areas of food research. However, when determining TPC in plant food extracts, the presence of reducing interferants [ascorbic acid (AA)] produces inaccurate estimations of TPC values. Different methodologies have been proposed to improve the specificity of the F–C assay. These methodologies include: (i) the use of solid phase extraction (SPE) cartridges to separate interferants from phenolics; (ii) the calculation of a corrected TPC value based on the AA reducing activity present in the extract; and (iii) the pre-treatment of extracts with oxidative agents prior to TPC quantification. These methods are described in detail in the present study. Likewise, their advantages and disadvantages are discussed based on new experimental data. A simple modification of the F–C assay procedure is proposed to quantify both the TPC value and the AA reducing activity in plant food extracts. Values obtained by the modified F–C assay can be used to estimate a corrected TPC value.

Optimization of edible coatings on minimally processed carrots using response surface methodology

Formation of a whitish, dried appearance (white blush) on the surface of peeled carrot pieces is a major factor reducing consumer acceptance of minimally processed carrot products. The optimization of sodium caseinate/stearic acid emulsion coating formulations was studied using response surface methodology. Optimization was based on the ability of edible coatings to increase water vapor resistance and reduce white blush measured by sensory and instrumental analysis. The effect of different sodium caseinate/stearic acid emulsion coatings on three different response parameters (water vapor resistance, whitish index, and sensory ranking of white blush) indicated that storage stability of peeled carrots can be improved with an optimized 1.4 to 1.6% sodium caseinate/0.1 to 0.2% stearic acid emulsion coating formulation.

Cross-talk between signaling pathways: The link between plant secondary metabolite production and wounding stress response

Plants subjected to wounding stress produce secondary metabolites. Several of these metabolites prevent chronic diseases and can be used as colorants, flavors, and as antimicrobials. This wound-induced production of plant secondary metabolites is mediated by signaling-molecules such as reactive oxygen species (ROS), ethylene (ET) and jasmonic acid (JA). However, their specific role and interactions that modulate the wound-respond in plants is not fully understood. In the present study, a subtractive cDNA library was generated, to better understand the global response of plants to wounding stress. Carrot (Daucus carota) was used as a model system for this study. A total of 335 unique expressed sequence tags (ESTs) sequences were obtained. ESTs sequences with a putative identity showed involvement in stress-signaling pathways as well as on the primary and secondary metabolism. Inhibitors of ROS biosynthesis, ET action, and JA biosynthesis alone and in combination were applied to wounded-carrots in order to determine, based on relative gene expression data, the regulatory role of ET, JA, and ROS on the wound-response in plants. Our results demonstrate that ROS play a key role as signaling-molecules for the wound-induced activation of the primary and secondary metabolism whereas ET and JA are essential to modulate ROS levels.

Biosynthesis of phenolic antioxidants in carrot tissue increases with wounding intensity

Biosynthesis of phenolic antioxidants in three carrots cultivars (Navajo, Legend and Choctaw) were studied under different wounding intensities (A/W) during storage. Generated A/W of 4.2, 6.0 and 23.5 cm(2)/g, corresponded to slices, pies, and shreds, respectively. Soluble phenolics, antioxidant capacity (AOX), and PAL activity increased with A/W for all cultivars. Intense wounding (23.5 cm(2)/g) induced an ∼2.5- and ∼12.4-fold increase in soluble phenolics and AOX, respectively, after 4 days compared to whole carrots. Wounding induced the synthesis of mainly chlorogenic acid (5-CQA) and 3,5-dicaffeoylquinic acid. A higher proportion of 5-CQA in the phenolic mixture was responsible for an increasing specific AOX (809 and 1,619 μg Trolox/mg phenolics for whole carrots and shreds, respectively, for Choctaw cultivar). Wounded carrots can be promoted as an inexpensive rich source of phenolic antioxidants for the regular diet. By simply increasing wounding stress intensity it is possible to enhance the biosynthesis of phenolic antioxidants.

Chlorogenic Acid: Recent Advances on Its Dual Role as a Food Additive and a Nutraceutical against Metabolic Syndrome

Chlorogenic acid (5-O-caffeoylquinic acid) is a phenolic compound from the hydroxycinnamic acid family. This polyphenol possesses many health-promoting properties, most of them related to the treatment of metabolic syndrome, including anti-oxidant, anti-inflammatory, antilipidemic, antidiabetic, and antihypertensive activities. The first part of this review will discuss the role of chlorogenic acid as a nutraceutical for the prevention and treatment of metabolic syndrome and associated disorders, including in vivo studies, clinical trials, and mechanisms of action. The second part of the review will be dealing with the role of chlorogenic acid as a food additive. Chlorogenic acid has shown antimicrobial activity against a wide range of organisms, including bacteria, yeasts, molds, viruses, and amoebas. These antimicrobial properties can be useful for the food industry in its constant search for new and natural molecules for the preservation of food products. In addition, chlorogenic acid has antioxidant activity, particularly against lipid oxidation; protective properties against degradation of other bioactive compounds present in food, and prebiotic activity. The combination of these properties makes chlorogenic acid an excellent candidate for the formulation of dietary supplements and functional foods.