M. L. Weaver

Anatomy and compositional variation within potatoes

Re-examination of the histological development of the potato tuber supports Artschwager’s view that tuber growth is predominantly due to enlargement of the perimedullary zone and is of procambial origin. Pith (medulla) and cortical regions are differentiated from the ground or fundamental meristem derived from the apical meristem of the stolon apex, even before tuberization has been initiated. The procambium gives rise to external phloem, primary xylem, internal phloem and associated parenchyma, and likewise to interfascicular parenchyma. Those parenchyma cells so formed inwardly to the xylem “ring” contribute to the growth of the perimedullary zone. The sequence of tissue origins is diagrammed and discussed from the viewpoint of modern concepts of histogenesis.ResumenLa reexaminación del desarrollo histológico del tubérculo de papa le da creencia al punto de vista de Artschwager que el crecimiento del tubérculo se debe sobretodo al engrandecimiento de la zona perimedular y es de origen procambial. La médula y las regiones corticales se desarrollan por la diferenciación del meristemo fundamental que se deriva del meristema apical del ápice del estolón, aún antes de que empiece la tuberización. El procambio de origen al floema external, xilema primario, floema internal y el parénquima asociado y también al parénquima inter-facicular. Las células parenquimáticas formadas hacia el interior en relación al “anillo” de xilema contribuyen al crecimiento de la zona perimedular. Se da un diagrama de la sucesión ed los orígenes de los tejidos y se discute la sucesión desde el punto de vista de los conceptos modernos de histogénesis.

Anatomy and compositional variations within potatoes. III. Gross compositional gradients.

The degree of compositional variations within potato tubers has been related to the development anatomy of the tuber and to exact tissues. The principal component, starch, shows differences in granule size distributions and in composition that appear when the young tuber averages about 1/300 of mature volumetric size. These differences pertain at maturity. When starch differences have been established, growth by cell divisions diminishes and growth by cell enlargement becomes dominant. In the mature tuber the general gradients for specific gravity, percent total solids, and percent total nitrogen decrease from stem end to bud end for cortical, perimedullary and pith tissues. Relationship between specific gravity and total solids is less parallel because differences in cell size and size of minute intercellular spaces also influence tissue density. Relationship between total solids and total nitrogen gradients from cortical tissue to pith were inverse with toal nirogen being higher in those tissues of lower total solids. These variations suggest need for new approaches in basic research on tuber quality improvement.ResumenEl grado de variaciones de la composición entre tubérculos de papa ha sido relacionado al desarrollo anatomico del tubérculo y a tejidos exactos. El componente principal, almidón, muestra diferencias en distribuciones de tamaño de gránulo y en la composición que aparecen cuando el volumen del tubérculo jóven tiene un promedio de 1/300 del volumen cuando maduro. Estas diferencias son pertinentes a la madurez. Cuando la diferencias en almidón hayan sidos establecidas, el crecimiento por division de células disminye y el crecimiento por agrandamiento de las células se hace dominante. En el tubérculo maduro el gradiente general de peso specifico, porcentaje de solidos totales, y el porcentaje de nitrogenos totales decrecn del punto del tallo (stem end) al punto apical (bud end) en los tejidos corticales, perimedulares y medula.La relación entre el peso específico y sólidos tales es menos paralelo porque laos diferencias en el tamaño de las celulas y el tamaño de los diminutos espacios intercelulares también influeyen en la densidad de tejidos. La relación entre gradientes de sólidos tolales y nitrógenos totales desde el tejido cortical a la médula fueron inversos para nitrógenes totales siendo mas altos en los tejidos de menor solidos totales. Estas variaciones indican la nececidad para nuevas metodas y ideas en las investigaciones básicas sobre el mejoramiento de la calidad del tubérculo.

French fry quality related to specific gravity and solids content variation among potato strips within the same tuber

The solids content of adjacent potato strips cut from known locations within the tuber was found to differ significantly. These strips were identified and processed according to commercial practice. The finish fries were subjectively scored for quality. Yield and oil uptake were calculated. The solids content of individual strips from a 20 tuber sample out of a single 100 lb. bag ranged from 12% to 29%. The whole tubers ranged from 18% to 23% solids. Strips below 17% solids were shriveled, limp and soggy after processing while strips above 22% solids were rigid and crisp with a mealy interior. Oil uptake was not related to solids content. However, yield of par-fries and to a lesser extent of finish-fries increased as solids content increased.ResumenSe encontró una diferencia significativa en el contenido de sólidos de bandas adyacentes de papas cortadas, en localidades conocidas, dentro del tubérculo Estas bandas fueron identificadas y procesadas de acuerdo al uso comercial. Las completamente papas fritas fueron subjetivamente calificadas de acuerdo a su calidad. Se calculó la productión y absorción de aceite. Los contenidos sólidos de bandas individuates provenientes de una muestra de 20 tubérculos sacados de una boisa individual de 100 lbs. variaron de 12% a 29%. Los tubérculos enteros variaron de 12% a 23% de sólidos. Las bandas conteniendo por debajo de 17% de sólidos resultaron estar marchitas, débiles y mojadas después de haber sido procesadas, mientras que las bandas conteniendo sólidos por encima de 22% fueron rigidas y crocantes y su interior era harinoso. La absorción de aceite no estuvo relacionada al contenido de sólidos. Sin embargo, la producción de papas parcialmente fritas y en menor extensión la de papas completamente fritas, incrementaron conforme aumentó el contenido de sólidos.

Parenchyma cell growth in potato tubers I. Different tuber regions

Enlargement rates of starch-storage parenchyma cells during growth of Kennebec and Russet Burbank potato cultivars were determined for cortical, perimedullary, and pith tissuues of bud ends, midsections, and stem ends of tubers. Average volumetric size of parenchyma cells increased 7 to 18x during growth of Russet Burbank tubers, with the greatest increases occurring in cortical and perimedullary cells of bud ends and midsections, and the least in stem ends and pith tissues. In Kennebec tubers parenchyma cells in both stem end and midsection increased only 5 to 8 x, whereas increases in bud ends ranged from 8 to 20 times.Cell enlargement to tuber enlargement ratios appproached unity early in growth of Russet Burbank tubers. As tubers increased beyond the 45 g size, cell enlargement and tuber enlargement rates were essentially equal. Calculations of cells per unit tissue volume agreed with ratio determinations. The timing of such unity appeared to be delayed in Kennebec tubers, and was not quite as pronounced as in Russet Burbank tubers. This may have been due to differences in growth rates of individual tubers in response to cultural conditions. In general, cells of harvestmature Kennebec tubers were about 60% as large as similar cells of Russet Burbank tubers.

Potato composition: II. Tissue selection and its effects on total sugar, total reducing sugar, glucose, fructose and sucrose contents

Total sugar, reducing sugar, glucose, fructose, and sucrose were determined in three parts (bud-end, stem-end, and core) of tubers of White Rose, Red La Soda, Kennebec, Russet Burbank, Norchip and Lenape. Tubers were sampled at harvest, after storage for 2 and 4 mo at 7 C, and after reconditioning for 3 wk at 20 C after each storage period. The quantity of different sugar fractions varied with cultivar and changed with storage treatments. Only sucrose was uniformly distributed among the different parts of the tuber. Except for fructose and sucrose the relationships among different parts of the tuber for distribution of all other sugar fractions varied significantly with cultivar, and these relationships among parts were not significantly changed by temperature, or duration of storage.ResumenAzúcares totales, azúcares reductores, glucosa, fructosa y sucrosa se determinaron en tres partes (ápice, base y centro) de tubérculos de White Rose, Red La Soda, Kennebec, Russet Burbank, Norchip y Lenape. Los tubérculos fueron muestreados a la cosecha, después de almacenamiento de 2 y 4 meses a 7° C, y después de re-acondicionar por 3 semanas a 20° C después de cada periodo de almacenamiento. La cantidad de las diferentes fracciones de azúcares variaron con el cultivar y cambiaron con los tratamientos de almacenamiento. Solo la sucrosa estuvo distribuída uniformemente entre las diferentes partes del tubérculo. Con la excepción de fructosa y sucrosa las relaciones de distribución entre las diferentes partes del tubérculo de todas las fracciones de azúcares variaron significativamente con el cultivar y esas relaciones entre partes no fueron cambiadas significativamente con la temperatura o con la duraci⤵ del almacenamiento.

Cell wall thickness during growth of domestic and foreign potato cultivars

During growth of Russet Burbank tubers from less than 100 to over 250 g, thickness of parenchyma cell walls nearly doubled (1.9X) to slightly over 1 μ. Although affecting cell size at harvest maturity, different levels of N fertilizer and soil moisture had little influence on wall thickness. Wall thickness in Kennebec and Norchip increased to 0.9μ (1.7X), and in White Rose to slightly under 0.8 (1.2X). During the same growth, cell size nearly doubled in Russet Burbank. Cells of Kennebec, Norchip and White Rose averaged smaller than those of Russet Burbank at harvest maturity.Wall thickness and cell size showed similar relationships in foreign cultivars. Wall thickness in European varieties Bintje and Pimpernel was comparable to that of White Rose. Thickness in Atjimba closely approached that of Russet Burbank, and in Kamarz was similar to that of Norchip. Among South American cultivars, Doré had unusually thick walls (1.36μ), whereas those in Fruitella and Papa Bianca were between those of Norchip and White Rose. Bintje was comparable to domestic cultivars in tuber size, but all other foreign cultivars studied had medium to small tubers. Doré had unusually large cells for a small tuber.Differences in wall thickness may be due to differences in amounts of cell wall material, to differences in hydration properties of pectic components, or to combinations of both. Independently of wall thickness, the many primary pit fields in parenchyma walls may be a limiting factor in wall strength. The very thin pit membranes consist mainly of cellulosic microfibrils formed early in cell growth.

Potato composition: I. Tissue selection and its effects on solids content and amylose/amylopectin ratios

Solids content and amylose/amylopectin ratios were determined in different parts of tubers of White Rose, Red La Soda, Kennebec, Russet Burbank, Norchip and Lenape at harvest, after storage at 7 C for 2 and 4 mo, and after reconditioning at 20 C for 3 wk following each storage period. In all cultivars, solids content was greatest in stem-end, lower in bud-end and lowest in core tissue. The relationships for distribution of solids among the different parts of the tubers was not changed by storage treatments in any of the cultivars. Amylose/amylopectin ratios were similar in all parts of the tuber. Both the solids content and amylose/amylopectin ratio were changed by storage, but not uniformly in all cultivars.ResumenEl contenido de sólidos y las proporciones de amilosa/amilopectina fueron determinados en diferentes partes de tubérculos de White Rose, Red La Soda, Kennebec, Russet Burbank, Norchip y Lenape a la cosecha, después de almacenamiento a 7°C por 2 y 4 meses, y después de reacondicionamiento a 20° C por 3 semanas después de cada periodo de almacenamiento. En todos los cultivares el contenido de soolidos fue mayor en la base, menor en el apice y mucho menor en el centro. Las relaciones de distributión de sólidos entre las diferentes partes del tubérculo no fué cambiada por el almacenamiento aninguno de los cultivares. Las proporciones de amilosa/amilopectina fueron similares en todas las partes del tuberculo. El contenido de sólidos y la proportión amilosa/amilopectina fueron cambiados por el almacenamiento, pero no uniformemente todos los cultivares.

26-Hydroxycholesterol and cholest-4-en-3-one, the first metabolites of cholesterol in potato plants

Abstract Etiolated potato sprouts convert administered cholesterol-4- 14 C to radioactive 26-hydroxycholesterol and cholest-4-en-3-one. These two steroids must be the first products of cholesterol metabolism in potato plants.

POTATO COMPOSITION: III. TISSUE SELECTION AND ITS EFFECTS ON TOTAL NITROGEN, FREE AMINO ACID NITROGEN AND ENZYME ACTIVITY (POLYPHENOLASE, MONOPHENOLASE, PEROXIDASE AND CATALASE)

Russet Burbank, Norchip, Kennebec, White Rose, Red La Soda and Lenape tubers were sampled at harvest, after storage for 2 and 4 mo at 7 C, and after 3 wk at 20 C following each storage treatment. Freeze-dried tissue from the bud-end, stem-end and core was analyzed for total, and free amino acid nitrogen, and for monophenolase, polyphenolase, peroxidase, and catalase activities. Significant differences among cultivars and among different parts of the tuber were found for all nitrogen fractions and all enzyme activities. Storage treatments significantly changed the total and free amino acid nitrogen contents and polyphenolase, peroxidase, and catalase activities. When compared for total nitrogen content and catalase activity, differences among different parts of the tuber which were statistically significant were similar in all cultivars. However, when compared for free amino acid content, and monophenolase, polyphenolase and peroxidase activities, differences among different parts of the tuber which were statistically significant were dependent upon which cultivar was examined. The differences among cultivars which were statistically significant for all nitrogen fractions and all enzyme activities, except peroxidase, were not significantly changed by storage treatment. The differences among different parts of the tuber which were statistically significant for quantity of both nitrogen fractions and for all enzyme activities were not significantly changed by storage.ResumenSe muestrearon tubérculos de Russet Burbank, Norchip, Kennebec, White Rose, Red La Soda y Lenape al momento de la cosecha, después de almacenamiento por 2 y 4 meses a 7° C, y después de tres semanas a 20° C, a continuación de cada tratamiento de almecenamiento.Tejido liofilizado de la parte apical, basal y central fue analizado para determinar N Total y N de aminoácidos libres y las actividades de monofenolasa, polifenolasa, peroxidasa y catalasa. Se encontraron diferencias significantes entre cultivares y entre las diferentes partes del tubérculo para todas las fracciones de N y para todas las enzimas. Los tratamientos de almacenamiento cambiaron significativamente el contenido de N Total y el N de aminoácidos libres y las actividades de polifenolasa, peroxidasa y catalasa. Cuando se comparé el contenido total de N y la actividad de catalasa, las diferencias entre las diferentes partes del tubérculo, las cuales fueron estadísticamente significantes, fueron similares en todos los cultivares. Sin embargo, cuando se comparé el contenido de aminoácidos libres y las actividades de menofenolasa, polifenolasa y peroxidasa, las diferencias entre las diferentes partes del tubérculo, las cuales fueron estadísticamente significantes, fueron dependientes del cultivar. Las diferencias entre cultivares, las cuales fueron estadísticamente significantes para todas las fracciones de N y para todas las actividades enzimáticas, excepto peroxidasa, no fueron estadísticamente cambiadas por el tratamiento de almacenamiento. Las diferencias entre las diferentes partes del tubérculo, las cuales fueron estadísticamente significantes para la cantidad de ambas fracciones de N y para todas las actividades enzimáticas, no fueron cambiadas significativamente por el almacenamiento.

OIL CONTENT OF FRENCH FRIES AS AFFECTED BY BLANCH TEMPERATURES, FRY TEMPERATURES AND MELTING POINT OF FRYING OILS

The oil content of par-fried frozen French fries prepared by two methods, conventional and freeze-leached, was not affected by blanch temperatures when blanched for 15 minutes. Melting points of the frying oil did affect the oil content of par-fried French fries. The differences were variable and could not be explained by melting point alone. Blowing the potato strips with ambient air after the par-fry and cooling below the melting point of the frying oil had no effect on the oil content of the frozen product. Contrary to previous reports, the oil content of the French fries increased significantly as the par-frying temperature was increased from 160.0 to 185°C (320 to 365°F) with the greatest increase occurring between 171.1 and 185.0°C (340 and 365°F). The French fries par-fried 1 min at 171.1 and 185.0°C (340 and 365°F) were judged to have identical quality after finish frying 3 minutes at 185.0°C (365°F). A lower par-fry temperature or possibly a shorter par-fry time at the higher temperature would be an advantage to the processor who could use less oil and energy without adversely affecting the quality of the final consumable product.ResumenEl contenido de aceite en papas parcialmente fritas (par-fried), congeladas y preparadas por dos métodos, el convencional y el de congelamiento y percolación (freeze-leached), no fue afectado Por las temperaturas del agua en el proceso de separación de la piel del tubérculo (blanching) por tiempos de 15 minutos. Los puntos de disdución del aceite de freir afectó el contenido de aceite de las papas parcialmente fritas. Las diferencias fueron variables y no pudieron ser explicados por el punto’de disolución solamente. El soplado las papas con una corriente de aire ambiental después de la fritura parcial y el enfriamiento por debajo del punto de disolución del aceite de fritura no tuvo efecto sobre el contenido de aceite del producto congelado. Contrariamente a reportes previos, el contenido de aceite de las papas fritas incrementó significativamente a medida que la temperatura de fritura parcial incrementó desde 160.0 a 185°C (320 a 365°F) el incremento mayor ocurrió entre 171.1 y 185.0°C (340 y 365°F). Las papas fritas parcialmente por 1 minuto a 171.1 y 185.0°C (340