Gabriela Burgos

Biotransformation of anthocyanins from two purple-fleshed sweet potato accessions in a dynamic gastrointestinal system

Cooked, milled purple-fleshed sweet potato (PFSP) accessions, PM09.812 and PM09.960, underwent digestion in a dynamic human gastrointestinal (GI) model that simulates gut digestive conditions to study the bioaccessibility and biotransformation of anthocyanins. Matrix-assisted laser desorption ionization time-of-flight mass spectrometry showed accession-dependent variations in anthocyanin release and degradation. After 24h, more anthocyanin species were detected in the small intestinal vessel relative to other vessels for accession PM09.960 whereas more species appeared in the ascending colonic vessel for accession PM09.812. The ferric reducing antioxidant power was increased in the small intestinal vessel for PM09.960 and in the ascending colonic vessel for accession PM09.812, corresponding to the appearance of a majority of anthocyanins for each accession. These results show that intestinal and colonic microbial digestion of PFSP leads to an accession-dependent pattern for anthocyanin bioaccessibility and degradation.

Traditional Processing of Black and White Chuño in the Peruvian Andes: Regional Variants and Effect on the Mineral Content of Native Potato Cultivars

Traditional Processing of Black and WhiteChuñoin the Peruvian Andes: Regional Variants and Effect on the Mineral Content of Native Potato Cultivars. Farmers in the high Andes of central to southern Peru and Bolivia typically freeze-dry potatoes to obtain chuño. Processing of so-called black chuño follows tending, treading, freezing, and drying. The making of white chuño is generally more complex and involves exposure of tubers to water. Regional variants exist for each of these processes, yet their influence on the nutritional composition of native potato cultivars is little known. Tubers belonging to four distinct cultivars and produced in a replicated trial under uniform conditions were processed into four types of chuño following standard traditional procedures (farmer-managed). These regional variants were documented, and the dry matter, iron, zinc, calcium, potassium, phosphorus, magnesium, and sodium content of the four resulting different types of boiled chuño determined at the International Potato Center’s Quality and Nutrition Laboratory (Lima, Peru). Content values were compared with those of boiled (unprocessed) tubers from the same experiment. Regional variants of processing are to a large extent determined by tradition, environmental condition, and market demand. The zinc, potassium, phosphorus, and magnesium content of all types of chuño decreases in comparison with unprocessed tubers. Concentrations of these same minerals decrease more drastically for white as compared to black chuño. The effect of the four regional variants of freeze-drying on the dry matter, iron, calcium, and sodium content of chuño differs by process and/or cultivar.Procesamiento tradicional dechuñonegro y blanco en los Andes Peruanos: Variantes regionales y efecto sobre el contenido de minerales en cultivares nativos de papa. Los agricultores de la zona Alto Andina del centro al sur del Perú y Bolivia someten a la papa a un proceso de congelado-secado para obtener chuño. El procesamiento del chuño negro involucra tender, pisar, congelar y secar. Por lo general la elaboración del chuño blanco es más compleja y requiere que los tubérculos se remojen en agua. Existen variantes regionales para cada uno de los procesos. Sin embargo, la influencia de estas sobre la composición nutricional de cultivares nativos es poco conocida. Tubérculos de cuatro cultivares distintos y producidos en un ensayo replicado bajo condiciones uniformes fueron procesados en cuatro ‘tipos’ de chuño siguiendo procedimientos tradicionales estándar (manejo de agricultor). Se documentaron las variantes regionales y se determinó el contenido de materia seca, hierro, zinc, calcio, potasio, fósforo, magnesio y sodio de los cuatro diferentes ‘tipos’ de chuño en el Laboratorio de Calidad y Nutrición del Centro Internacional de la Papa (Lima, Perú). Se compararon los valores de contenido del chuño con los de tubérculos hervidos (sin procesar) provenientes del mismo experimento. Los variantes regionales de procesamiento se determinan principalmente por tradición, condición ambiental y demanda de mercado. El contenido de zinc, potasio, fósforo y magnesio de todos los tipos de chuño disminuyó en comparación con tubérculos sin procesar. Las concentraciones de estos minerales disminuyó más drásticamente para chuño blanco comparado con chuño negro. El efecto de los cuatro variantes de congelado-secado sobre el contenido de materia seca, hierro, calcio y sodio del chuño varió dependiendo del proceso y/o cultivar.

In Vitro Bioaccessibility and Bioavailability of Iron from Potatoes with Varying Vitamin C, Carotenoid, and Phenolic Concentrations

The bioaccessibility and bioavailability of iron from 12 Andean potato clones were estimated using an in vitro gastrointestinal digestion procedure and the Caco-2 cell line as a model of human intestine, with ferritin formation as a marker of iron absorption. We first showed that 63.7% (for the genotype CIP_311422.016) to 79.0% (for the genotype CIP_311575.003) of the iron is released from the potato tuber matrix during in vitro gastrointestinal digestion and is therefore available at the intestinal level. On average, 32 and 24.5% of the hydrophilic bioactive components, vitamin C and chlorogenic acid, respectively, were also bioaccessible from boiled tubers. Intestinal absorption of intrinsic iron from potato tubers could not be detected using our in vitro Caco-2 cell model. When an extrinsic source of iron (20 μM FeCl3 and 1 mM ascorbic acid) was added to the digestion mixture, iron absorption varied from 1.8 to 8% for the genotypes CIP_311422.016 and CIP_311624.021, respectively, as compared to the reference control. Principal component analysis revealed negative relationships between bioavailable iron values and phenolic concentrations, whereas vitamin C concentrations were positively associated with the ferritin values. Further controlled intervention trials would be needed to conclusively assess the bioavailability of intrinsic iron from potato tubers.

Effects of Simulated Human Gastrointestinal Digestion of Two Purple-Fleshed Potato Cultivars on Anthocyanin Composition and Cytotoxicity in Colonic Cancer and Non-Tumorigenic Cells

A dynamic human gastrointestinal (GI) model was used to digest cooked tubers from purple-fleshed Amachi and Leona potato cultivars to study anthocyanin biotransformation in the stomach, small intestine and colonic vessels. Colonic Caco-2 cancer cells and non-tumorigenic colonic CCD-112CoN cells were tested for cytotoxicity and cell viability after 24 h exposure to colonic fecal water (FW) digests (0%, 10%, 25%, 75% and 100% FW in culture media). After 24 h digestion, liquid chromatography-mass spectrometry identified 36 and 15 anthocyanin species throughout the GI vessels for Amachi and Leona, respectively. The total anthocyanin concentration was over thirty-fold higher in Amachi compared to Leona digests but seven-fold higher anthocyanin concentrations were noted for Leona versus Amachi in descending colon digests. Leona FW showed greater potency to induce cytotoxicity and decrease viability of Caco-2 cells than observed with FW from Amachi. Amachi FW at 100% caused cytotoxicity in non-tumorigenic cells while FW from Leona showed no effect. The present findings indicate major variations in the pattern of anthocyanin breakdown and release during digestion of purple-fleshed cultivars. The differing microbial anthocyanin metabolite profiles in colonic vessels between cultivars could play a significant role in the impact of FW toxicity on tumor and non-tumorigenic cells.

Procedures for sampling and sample preparation of sweetpotato roots and potato tubers for mineral analysis.

This publication was developed under the “Nutritional Quality Assurance and Enhancement Network (NQAEN)” financed by CGIAR Research Programs on ‘Agriculture for Nutrition and Health (CRP-A4NH)’ and ‘Roots, Tubers and Bananas (CRP-RTB)’; and HarvestPlus project ‘Bio-fortified potato varieties to help overcome micronutrient malnutrition in East Africa’ The International Potato Center (known by its Spanish acronym CIP) is a research-for-development organization with a focus on potato, sweetpotato, and Andean roots and tubers. CIP is dedicated to delivering sustainable science-based solutions to the pressing world issues of hunger, poverty, gender equity, climate change and the preservation of our Earth’s fragile biodiversity and natural resources. www.cipotato.org

Micro-nutrient composition and end-user acceptable quality in potato in Ethiopia

ABSTRACT Micronutrient deficiencies in diets, including iron (Fe) and zinc (Zn), are an important public health problem across population in Ethiopia. Potato is a modest source of dietary nutrients. The purpose of this study was to assess the mineral (Fe & Zn) composition of potato germplasm in Ethiopia and growers willingness to try new potato types. The Fe and Zn contents were assessed in peeled tubers of popular farmer varieties, and newly introduced Andean diploid group Phureja accessions and improved tetraploid clones grown in multi-location trials. Growers preferences for the new potato types was assessed using a participatory approach. Significant variations in mineral and tuber yield traits exist among the germplasm assessed and broad-sense heritability appears to be high for most traits measured, suggesting that progress through breeding can be made among these materials. However, the slightly negative correlation of tuber yield with Fe and Zn content and user appreciation traits found in this study suggests that progress in improving crops for yield and enhanced Fe and Zn concentrations with end-user acceptable quality will be challenging. The results from this study provide baseline information on Fe and Zn composition of many popular farmer varieties in Ethiopia and end-user preference criteria for evaluating new potato varieties that would help to orient the biofortification breeding to the conditions and preference of farmers.

Heritability for yield and glycoalkaloid content in potato breeding under warm environments.

Abstract High temperatures affect potato production in the tropics, putting tuber yield and quality at risk and leading to increased glycoalkaloid concentration the cause of the bitter taste in potatoes and a cause for concern for human health. The International Potato Center (CIP), has developed new heat tolerant clones which are heat tolerant and also resistant to late blight. These clones offer an opportunity to evaluate yield and glycoalkaloid levels after growth under high temperature environments. We evaluated four sets of 16 full-sib families and 20 clones for tuber yield and glycoalkaloid content in order to estimate narrow-sense and broad-sense heritability respectively. We used a randomized complete block design replicated in three locations in Peru; San Ramon, La Molina and Majes At harvest, the number and weight of marketable and nonmarketable tubers were recorded. We analyzed samples of tubers from each clone for glycoalkaloid content using spectrophotometry. Narrow-sense heritability for tuber yield, tuber number and average tuber weight were 0.41, 0.50 and 0.83, respectively, indicating that further gains in breeding for heat tolerance will be possible. Broadsense heritability for glycoalkaloid content was 0.63 and correlation with tuber yield was weak, r=0.33 and R²=0.11 (P<0.01). High heritability and weak correlation will allow us to select clones with high tuber yield and low glycoalkaloid content, to serve as candidate varieties and parents in breeding programs.