Nell I. Mondy

The effect of phosphorus fertilization on the chemical quality of Katahdin potatoes.

The influence of phosphorus fertilization on the content of ascorbic acid, lipids, total nitrogen, protein, and non-protein nitrogen of Katahdin potatoes was investigated. Phosphorus in the form of mono ammonium phosphate was applied at rates of 0, 56, 112, and 168 Kg/ha (0, 50, 100, and 150 lb/acre). Ascorbic acid, total nitrogen, protein and non-protein nitrogen content were significantly increased (p<.01) and the phospholipid content was significantly reduced (p<.01) by phosphorus application.ResumenLa influencia de la fertilización en el contenido de ácido ascórbico, lípidos, Nitrógeno total, proteínas, y nitrógeno no proteico de las papas Katahdin fue investigado. Fósforo en la forma de fosfato monoamónico fue aplicado a las dosis de 0, 50, 100 y 150 lb/acre. El contenido de ácido ascórbico, Nitrógeno total, proteína y Nitrógeno no proteico fue aumentado significativamente (p<0.1) el contenido de fosfolípidos fue significativamente reducido (p<0.1) por la aplicacióon de fósforo.

Glycoalkaloid and nitrate content of potatoes as affected by method of selenium application

A comparison of two methods of selenium application, banding and foliar spray, of sodium selenite (Na2SeO3) on total glycoalkaloid (TGA) and nitrate nitrogen (NO3-N) was studied during each of two consecutive years. The levels of application used were 0.0, 1.6 (0.75), 3.36 (1.5), and 5.6 (2.5) kg/ha (ppm soil). Both TGA and NO3-N were significantly reduced by application of 1.5 and 2.5 ppm of sodium selenite. Tuber selenium levels were significantly increased at all levels of application, using either banding or foliar spray, but were well below the toxic range for human consumption. Banding resulted in greater uptake of Se, and greater decreases in TGA and NO3-N as compared to foliar spray.

Enzymatic discoloration and phenolic content of potato tubers from cultivars resistant and susceptible to the golden nematode

Phenolic content and discoloration were determined for 13 commercial potato cultivars and 6 potato clones grown at 2 locations over a period of 5 successive years. Tubers from 6 potato cultivars and 5 potato clones resistant to the golden nematode were compared with tubers from 7 potato cultivars and 1 clone known to be susceptible to the golden nematode. Tubers from resistant plants were lower in phenols and discolored less than tubers from susceptible plants.ResumenSe determinó el contenido de fenoles y la descoloración en 13 cultivares comerciales y 6 clones de papa, cultivados en 2 localidades, durante un período de cinco años sucesivos. Los tubérculos de 6 cultivares y 5 clones resistentes al nematodo dorado fueron comparados con los tubérculos de 7 cultivares y un clon conocidos como susceptibles al nematodo dorado. Los tubérculos de las plantas resistentes tuvieron cantidades menores de fenoles y se descoloraron menos que los tubérculos de las plantas susceptibles.

Residue levels of isopropyl N-(3-chlorophenyl) carbamate (CIPC) in potatoes as affected by level of application, storage time and temperature, and method of cooking

Abstract Katahdin potato tubers were treated with 1 and 3% CIPC and the various tissue sections were analyzed for CIPC residue using a modified High Pressure Liquid Chromatographic method. Tubers were analyzed for CIPC residue immediately following the CIPC treatment as well as after 6 months of storage. Increasing CIPC concentration significantly ( p ≤ 0·001) increased residue level in tubers stored at both 5°C and 20°C for 6 months. CIPC residue was highest in the peel, followed by the cortex with peel and cortex without peel, with little or no residue in the pith. The CIPC residue level was higher in tubers stored at 5°C as compared to those stored at 20°C, and the residue level decreased during storage. Cooking resulted in decreased residue levels in all the sections of the tuber due to leaching of CIPC into the cooking water. The amount of residue in the cooking water was higher when tubers were boiled as compared to steaming.

A review of environmental and health risks of maleic hydrazide

The cellular metabolism, acute toxicity, mutagenicity, and carcinogenicity of maleic hydrazide have been reviewed. It seems that this chemical is a mutagen and a carcinogen in cell cultures and animals, but no evidence is available on human carcinogenicity regardless of population exposure in manufacturing, agriculture, and the food chain (i.e., potatoes, potato chips). Because of the level of exposure of the general public to this compound, an epidemiologic survey should be conducted to ascertain possible human health effects. Long-term feeding experiments should be conducted in several animal species to establish whether maleic hydrazide is carcinogenic by this route. Biotransformation and pharmacokinetic studies should be undertaken to obtain better understanding of the chemicals metabolism and excretion. Such investigations would firmly establish whether the tolerance for maleic hydrazide should remain unchanged or whether the use of the compound should be more restricted.

The interrelationships of potato discoloration, polyphenol oxidase activity, and nitrogen content of potatoes

SummaryThe relationship of tuber macerate discoloration to polyphenol oxidase activity and nitrogen content of potatoes was studied. Two varieties of potatoes, Ontario which is susceptible to pre-cooking discoloration and Pontiac which exhibits little discoloration were studied.Ontario potatoes discolored more than Pontiac potatoes and were higher in polyphenol oxidase activity. Upon storage, however, the greater percentage loss in polyphenol oxidase activity occurred in Ontario potatoes. The tendency of the tuber to discolor was significantly correlated with the loss of polyphenol oxidase activity. More discoloration occurred in the Ontario variety which also showed the greater loss in polyphenol oxidase activity.Total nitrogen content of both varieties increased with storage duration. The non-protein nitrogen decreased during storage, indicating that protein synthesis occurred. More protein synthesis occurred in Ontario than in Pontiac potatoes. Discoloration of potato macerates was not correlated with protein synthesis.

The effect of cooking methods on the lipid composition of potatoes

The effect of boiling and baking in either a convential or microwave oven on the lipid content of potatoes was investigated. The crude lipid content of potatoes was lowered significantly by all methods of cooking. The loss was highest in potatoes cooked in a microwave oven, least in boiled tubers, and intermediate in tubers baked in a conventional oven. Similar trends were observed for both cortex and pith tissues. Generally, the phospholipid content followed the same trend as the crude lipid, the exception being the cortex tissue of tubers baked in the conventional oven, in which the greatest loss of phospholipid occurred. Cooking did not significantly alter the fatty acid composition of tubers. A possible relationship between the degree of cell rupturing, known to be influenced by different mechanisms of heat transfer, and the amounts of tuber lipid associated with different cooking methods was discussed.ResumenEl efecto de sancochar y hornear en un horno convencional o de microonda sobre el contenido de lípidos de papas fue investigada. El contenido de lípidos crudos de las papas fue bajado significativamente por todos 1 os métodos de cocción. La pérdida fue mas alta con papas cocidas en un horno de microonda, menor en tubérculos sancochados, e intermedia en tubérculos horneados en un horno convencional. Tendencias similares fueron observados para ambos tejidos, la corteza y la médula. Generalmente, el contenido de fosfolípidos siguió la misma tendencia que los lípidos crudos, a exceptión del tejido cortical de los tubérculos horneados en un horno convencional y en el cual ocurrió la mayor pérdida de fosfolí-pidos. La cocció no alteró significativamente la compositión de ácidos grasos de los tubérculos. Una posible relatión entre el grado de ruptura celular, que como se sabe es influenciada por diferentes mecanismos de transferencia de calor, y por las cantidades de lípidos del tubérculos asociados con los diferentes métodos de cocción es discutida.

Effect of method of irrigation on the total glycoalkaloid and nitrate-nitrogen content of Rosa potatoes

The effect of two irrigation methods, microjet mist and impact sprinkler, on the total glycoalkaloid (TGA) and nitrate-nitrogen (NO3−N) content ofSolanum tuberosum L. cv. Rosa was investigated. Potatoes irrigated by microjet mist were significantly higher in TGA and lower in NO3−N content than control potatoes receiving no irrigation. The impact sprinkler method produced potatoes significantly higher in NO3−N than controls. The TGA content of potatoes irrigated by the sprinkler method was not significantly different from controls. Mist-irrigated potatoes were higher in TGA and lower in NO3−N content than sprinkler-irrigated potatoes.

Quality of potato tubers as affected by freezing: I. texture, ascorbic acid and enzymatic discoloration

The effect of freezing on the turgor, ascorbic acid content and enzymatic discoloration of Katahdin and Atlantic potatoes was studied. Tubers were exposed to a temperature of −20°C for 24 hrs. then thawed for 1 hr. at 20°C before analysis. Frozen tubers were then compared with unfrozen controls.Both varieties lost turgor following freezing and exuded a sticky liquid with increased thawing time. At the end of 3 hrs. thawing, a sponge-like texture was observed in both varieties. In both varieties freezing resulted in a significant reduction (p<.01) in ascorbic acid and phenolic content (p<.01). Enzymatic discoloration was also significantly reduced (p<.01) in both varieties.ResumenEl efecto de congelamiento en turgencia, contenido de ácido ascórbico y decoloración enzimática de papas Katahdin y Atlantic, fue estudiado. Los tubérculos fueron expuestos a temperaturas de 20°C durante 24 hrs luego derretidos durante 1 hr a 20°C antes de analizarlos. Tubérculos congelados fueron luego comparados con los testigos no congelados. Ambas variedades, perdieron turgencia luego del congelamiento y exudaron un líquido pegajoso al aumentar el tiempo de derretido. Al cabo de 3 horas de derretido, so observó una textura esponjosa en ambas variedades. En ambas variedades el congelamiento resultó en una reducción significativa (p<0.1) en ácido ascórbico y contenido fenólico (p<0.1).La decoloración enzimático fue tambien significativamente reducida (p<0.1) en ambas variedades.

Lipid composition of potatoes during sprouting

The purpose of the study was to determine the lipid composition of potatoes during sprouting. Sprouts from Pontiac and Katahdin potatoes as well as two clones (the genetic material from crosses of a population ofSolanum andigenum from South America andSolanum tuberosum from North America) were found to be significantly higher in crude lipid than either the cortex or pith sections of the tuber. The cortex section was found to be higher in lipid than the pith section. Crude lipid was fractionated into phospholipid, neutral fat, and free fatty acids, and for each of the sections of potatoes the highest percentage of lipid was found in the phospholipid fraction. The fatty acid found in highest concentration in the phospholipid fraction was linoleic acid, but considerable quantities of linolenic and palmitic acids were also present. Synthesis of phospholipid occurs in the actively growing sprout, and compounds that interfere with lipid synthesis, particularly phospholipid synthesis, should prove to be effective sprout inhibitors.ResumenEl proposito de este estudio fue el de determinar la composición de lípidos en papas durante el periodo de brotamiento. El analisis de brotes de las variedes “Pontiac,” “Katahdin” ty dos clones (material genetico obtenido de cvoces entreSolanum andigenum de Sud America ySolanum tuberosum de Norte America) demuestran result ados altamente significativos en contenidos más altos de lípidos impuros que los respectivos tumérculos. Los brotes contenian un nivel mas elevado de lípidos que el de la corteza o de la medula de los tuberculos. Los lipidos impuros fueron fraccinados en fosfolípidos, ácidos grasos neutros, y ácidos grasos libres. La fraccion lípidica de mas alto porcentaje fue la de los fosfolípidos. El ácido graso de más alta concentracion que fue hallado en los brotes fue el ácido linoléico, pero cantidades notables de acidos linolenico y palmitico tambien se encontraron presentes. Una distribucion similar de ácidos grasos fue encontrada en cada una de las tres fracciones. La sintesis de fosfolípidos demuestra ser una actividad de suma importancia en el proceso de crecimiento de brotes, parec que los ácidos grasos no saturados. predominan. Los compuestos que se interponen a la sintesis de lípidos, en particular con la de fosfolípidos, podrian ser inhibidores efectivos de brotamiento.