Anna L. Hale

Determination of phenolic content, composition and their contribution to antioxidant activity in specialty potato selections

In order to identify elite parental lines for use in breeding programs emphasizing human health benefits, specialty (colored) potato selections from the Texas Potato Variety Development Program were analyzed for antioxidant activity (AA) using 2,2-diphenyl-l-picrylhy-drazyl (DPPH) and 2,2-azinobis (3-ethyl-benzothiazo-line-6-sulfonic acid) (ABTS) radical assays, total phenolic content (TP) using Folin-Ciocalteu reagent (FCR), and phenolic composition using high performance liquid chromatography (HPLC). Total AA ranged from 157 μg trolox equivalents (TE)/gfw to 832 μg TE/gfw and 810 μg TE/gfw to 1622 μg TE/gfw using the DPPH and ABTS assays, respectively. TP ranged from 221 μg chlorogenic acid equivalents (CGAE)/gfw to 1252 μg CGAE/gfw. Selection COH2F2-2P/P had the highest AA and TP. Purple flesh selections had the highest AA and TP, followed by red flesh and yellow flesh selections. Selections with similar flesh color did not differ significantly in AA and TP. A significant positive correlation was observed between AA and TP. Chlorogenic acid, gallic acid, catechin, caffeic acid, and malvidin-3-(p-coumaryl rutinoside)-5-galactoside were the major polyphenols identified. Chlorogenic acid accounted for 50 to 70% of TP, followed by catechin, gallic acid and caffeic acid. Contribution of individual phenolics in specialty potatoes to AA was calculated using pure standards. Chlorogenic acid contributed 28 to 45% to AA, followed by gallic acid, catechin and caffeic acid.ResumenCon el fin de identificar líneas selectas de progenitores para utilizarlas en programas de mejoramiento, poniendo énfasis en beneficios de la salud humana, se analizaron selecciones de papa de pulpa coloreada del Programa de Mejoramiento de Variedades de Papa de Texas para determinar la actividad antioxidante (AA), utilizando ensayos con el radical 2,2 difenil-1-picrilhidracida (DPPH) y 2,2 azinobis (3-etil-benzotiazolina-6-ácido sufünico) (ABTS), contenido total fenülico (TP) utilizando el reactivo Folin-Ciocalteu (FCR) y la compositiün fenülica utilizando la cromatografía líquida de alta resolutiün (HPLC). El total de AA variü de 157 μg equivalentes trolox (TE)/gfw a 832 μg TE/gfw y de 810 μg TE/gfw a 1622 pg TE/gfw utilizando las pruebas DPPH y ABTS respectivamente. El TP registrü de 221 μg equivalentes de ácido clorogénico (CGAE)/gfw a 1252 μg CGAE/gfw. La selectiün COH2F2-2P/P tuvo los más altos AA y TP. Las selecciones con pulpa morada tuvieron los más altos AA y TP seguidos de selecciones de pulpa roja y amarilla. Selecciones con color de pulpa similar no se diferenciaron significativamente en AA y TP. Una correlatiün positiva significativa se observü entre AA y TP. Los principales polifenoles identificados fueron ácido clorogénico, ácido gálico, catequina, ácido cafeico y malvidina-3-(p-cumaril rutinosida)-5-galactosida. El ácido clorogénico fue estimado en 50 a 70% de TP, seguido de catequina, ácido gálico y ácido cafeico. La contributiün de fenoles individuales a AA en papas especiales fue calculada utilizando estándares puros. El ácido clorogénico contribuyü de 28 a 45% a AA, seguido por ácido gálico, catequina y ácido cafeico.

The Effects of Low-Dose Gamma Irradiation and Storage Time on Carotenoids, Antioxidant Activity, and Phenolics in the Potato Cultivar Atlantic

Potatoes are stored to ensure a continuous supply; however, losses due to shrinkage and sprouting can be large. It is believed that low-dose ionizing irradiation will become more prominent for sprout inhibition due to the increasingly higher operating costs of low-temperature storage and the possible phase-out of chemical sprout inhibitors. The effects of storage and gamma irradiation on carotenoid content, antioxidant activity (AOA), and phenolic content were analyzed for the potato cultivar Atlantic. Tubers were subjected to 0, 75, and 200 Gy gamma irradiation doses, stored at 20 C, and analyzed after 0, 10, 20, 75, and 110 days in storage. Total carotenoid content determined via spectrophotometry decreased, while lutein content increased with storage. AOA appeared to first decrease and then increase, possibly due to dehydration, concentration, and/or induced stress. Phenolic content increased more with storage than with gamma irradiation. However, levels of some phenolic compounds, such as quercetin dehydrate, decreased with storage. Irradiation dose exerted a limited influence on AOA and phenolic and carotenoid contents. Interaction between storage time and irradiation dose was significant for AOA and phenolic content, but not for carotenoid content. Overall, storage exerted a much greater influence on carotenoid content, AOA, and phenolic content than did low-dose gamma irradiation.ResumenLas papas son almacenadas para asegurar el abastecimiento continuado, pero las pérdidas por reducción y por brotamiento pueden ser grandes. Se cree que una dosis baja de irradiación ionizante sería més prominente en la inhibición del brotamiento debido a los cada vez mayores costos de operación para mantener baja la temperatura de almacenaje y la posible eliminación de inhibidores químicos. Se analizaron los efectos del almacenaje y la irradiación gamma del contenido carotenoide, actividad antioxidante (AOA) y del contenido fenólico en el cultivar Atlantic. Los tubérculos fueron sometidos a dosis de 0, 75 y 200 Gy de irradiación gamma, almacenados a 20 C y analizados a los 0, 10, 20, 75 y 110 días. Con el almacenaje, el contenido total de carotenoides, determinado por medio de espectrofotometría, disminuyó, mientras que aumentó el contenido de luteína. AOA parece disminuir inicialmente y luego incrementarse, debido posiblemente a la deshidratación, concentración y/o estrés inducido. El contenido fenólico aumentó más con el almacenaje que con la irradiación gamma, sin embargo, disminuyeron los niveles de algunos compuestos como el dehidrato de quersitina. La dosis de irradiación ejerció una influencia limitada sobre AOA y contenidos fenólicos y carotenoides. La interacción entre tiempo de almacenaje y dosis de irradiación fue significativa para AOA y contenido fenólico, pero no para contenido carotenoide. El almacenaje ejerció mayor influencia sobre el contenido carotenoide, AOA y contenido fenólico que las dosis bajas de irradiación gamma.

Estimating Broad Sense Heritability and Investigating the Mechanism of Genetic Transmission of Cold Tolerance Using Mannitol as a Measure of Post-freeze Juice Degradation in Sugarcane and Energycane (Saccharum spp.)

In approximately 25% of the sugarcane-producing countries worldwide, conventional sugarcane (Saccharum spp. hybrids) is exposed to damaging freezes. A study was conducted during the 2009 and 2010 harvest seasons to compare late-season freeze tolerance among three groups: commercial Louisiana sugarcane genotypes, early generation genotypes selected for cold tolerance in the U.S. Department of Agriculture sugarcane breeding programs at Houma, LA, and Canal Point, FL, and potential energycane genotypes selected for high total biomass per acre. Mannitol concentrations in cane juice following freezing temperatures were determined to evaluate levels of cold tolerance. Genotypes selected for cold tolerance in Houma, LA, had significantly more late-season freeze tolerance than commercial sugarcane genotypes and genotypes selected in Canal Point, FL. Genotypes showing the most cold tolerance were Ho02-146 and Ho02-152, and those that were most highly susceptible were US87-1006 and US87-1003 (early-generation breeding genotypes) and L99-233 (commercial genotype). Broad-sense heritability for late-season cold tolerance in the two-year study was estimated at g(2) = 0.78. The enzymatic mannitol analysis successfully differentiated high-fiber energycane genotypes from those from other sources.