Lower Color Intensity Research Articles

Organosoluble and light‐colored fluorinated polyimides from 4,4′‐bis(4‐amino‐2‐trifluoromethylphenoxy)biphenyl and aromatic dianhydrides

AbstractA novel fluorinated diamine monomer based on 4,4′‐biphenol was synthesized via a straightforward, high‐yielding two‐step procedure. 4,4′‐Biphenol was reacted with 2‐chloro‐5‐nitrobenzotrifluoride in the presence of potassium carbonate to yield the intermediate dinitro compound, which was subsequently reduced to afford the fluorinated diamine, 4,4′‐bis(4‐amino‐3‐trifluoromethylphenoxy)biphenyl. A series of organosoluble fluorinated polyimides were prepared from the diamine with various aromatic dianhydrides via a conventional two‐step thermal imidization method. All polyimides were soluble in strong dipolar solvents such as N‐methyl‐2‐pyrrolidone and N,N‐dimethylacetamide. The polyimides showed excellent thermal and thermooxidative stability and good mechanical properties. No significant weight loss was observed below a temperature of 520 °C in nitrogen or in air, and the glass‐transition temperatures ranged from 247 to 313 °C. Low dielectric constants (2.57–3.65 at 10 kHz), low moisture absorption (0.1–0.7 wt %), and low color intensity were also observed. © 2002 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 524–534, 2002; DOI 10.1002/pola.10113

GRAPE AND WINE POLYPHENOLIC COMPOSITION OF RED Vitis vinifera VARIETIES CONCERNING VINEYARD ALTITUDECOMPOSICIÓN POLIFENÓLICA DE UVAS Y VINO DE VARIEDADES TINTAS DE Vitis vinifera EN FUNCIÓN DE LA ALTITUD DEL VIÑEDOCOMPOSICIÓN POLIFENÓLICA DE UVAS E VIÑO DE VARIEDADES TINTAS DE Vitis vinifera EN FUNCIÓN DA ALTITUDE DO VIÑEDO

The effect of altitude and its related climatic conditions on the polyphenolic composition (procyanidin and anthocyanin compounds) of grapes and wines of Touriga Nacional and Touriga Francesa red varieties is reported (Douro Region, 1997). The levels of catechin monomers ((+)-catechin, (−)-epicatechin, (−)-epicatechin O-gallate), detected procyanidin oligomers (B1 to B8, B2-3′′-O-gallate and trimer C1) and total extractable proanthocyanidins were analysed at harvest in grape skin and seeds as well as the anthocyanidin monoglucosides composition in grape skin. Chemical and sensorial analysis of the resulting Port wines was performed. Higher levels of anthocyanins in grape skin were found at higher altitude, whereas procyanidin compounds were produced in larger amounts at low altitude for both skin and seeds. Despite having lower colour intensity, higher levels of anthocyanins were present in wines made from higher altitude grapes. Overall, low altitude appears to be most advantageous for general wine quality. © 2001 Altaga All rights reserved. Resumen Se ha estudiado el efecto de la altitud y sus condiciones climáticas sobre la composición polifenólica (procianidina y antocianina) de uvas y vinos de las variedades tintas Touriga Nacional y Touriga Francesa (Región del Douro, 1997). El nivel de monómeros de catequinas ((+)-catequina, (−)-epicatequina, (−)-epicatequina O-galato), oligómeros de procianidina detectados (B1 a B8, B2-3′′-O-galato y trimer C1) y proantocianidinas totales extraibles se analizaron en pieles y semilla de uvas vendimiadas así como la composición de antocianidinas monoglucosídicas en pieles de uva. Se realizaron análisis químicos y sensoriales de los vinos de Porto resultantes. Se encontraron niveles altos de antocianinas en pieles de uvas procedentes de altitudes altas, mientras que las procianidinas se produjeron en cantidades mayores a bajas altitudes en ambas, pieles y semillas. No obstante, menor intensidad de color y mayores niveles de antocianinas estuvieron presentes en vinos de hechos con uvas de altitudes altas. Globalmente, la altitud baja parece tener mejores ventajas para la calidad general del vino.© 2001 Altaga. Todos los derechos reservados. Palabras clave: Touriga, viñedo, vino, uva, polifenoles, antocianinas, procianidinas Resumo Estudouse o efecto da altitude e as súas condicións climáticas sobre a composición polifenólica (procianidina e antocianina) de uvas e viños das variedades tintas Touriga Nacional e Touriga Francesa (Rexión do Douro, 1997). O nivel de monómeros de catequinas ((+)-catequina, (−)-epicatequina, (−)-epicatequina O-galato), oligómeros de procianidina detectados (B1 a B8, B2-3′′-O-galato e trimer C1) e proantocianidinas totais extraibles analizáronse nas peles e sementes de uvas vendimadas así coma a composición de antocianidinas monoglucosidicas nas peles de uva. Realizáronse análises químicas e sensoriais dos viños de Porto resultantes. Encontráronse niveis altos de antocianinas nas peles de uvas procedentes de altitudes altas, mentras que nas procianidinas produxéronse en cantidades maiores a baixas altitudes en ámba-las dúas, peles e sementes. Sem embargo, menor intensidade da cor e maiores niveis de antocianinas estiveron presentes nos viños elaborados con uvas de altitudes altas. Globalmente, a altitude baixa parece ter mellores ventaxas para a calidade xeral do viño. © 2001 Altaga. Todolos dereitos reservados. Palabras chave: Touriga, viñedo, viño, uva, polifenois, antocianinas, procianidinas

Efeito de três processos de vinificação sobre a composição química e a qualidade do vinho Cabernet Franc

Foram avaliados os efeitos de três processos de vinificação sobre a composição química e a qualidade do vinho Cabernet Franc, nas safras de 1987 a 1990. As vinificações foram realizadas em escala industrial, pelos processos clássico, de termovinificação e de maceração carbônica. Avaliaram- se teor alcoólico, acidez total, açúcares redutores, cinzas, extrato seco, compostos fenólicos e voláteis e elementos minerais. Procedeu-se, também, à análise sensorial dos vinhos. Os resultados foram submetidos à análise de componentes principais (ACP) e à análise de variância, sendo que os três primeiros eixos explicaram 68,2% da variação total. Através da ACP, foi possível separar os vinhos de maceração carbônica dos outros dois processos de vinificação. As variáveis que apresentaram maior efeito na variação foram os álcoois superiores, os cátions e os compostos fenólicos. A avaliação sensorial mostrou que a maceração carbônica originou vinhos leves e com menor intensidade de cor, e a termovinificação e a vinificação clássica originaram vinhos com mais corpo, melhor qualidade e equilíbrio gustativo e maior tipicidade varietal.

Market Quality of Sweetpotatoes after Gamma-irradiation for Weevil Control

Roots of sweetpotatoes [Ipomoea batatas (L.) Lam.] were treated with 200 to 1000 Gy of ionizing radiation from a 60Co source. Within this range, radiation dosage had no effect on surface injury and decay when roots were evaluated after 1 month of storage at 13C and 90% relative humidity. During storage, weight loss by irradiated roots was 0.5% to 3.3% over that of nontreated roots, which, in some instances, affected root firmness. Changes in peel color were visually imperceptible, but raw medullar tissue of the staple-type, white-fleshed cultivar Picadito had a more intense yellow hue with increasing irradiation. The greatest differences were evident after roots had been baked. The hue of the cooked medullar tissue of the sweet, orange-fleshed cultivar Jewel was not changed by increasing irradiation, although roots were darker and had a lower color intensity. With baking, the medullar tissue of irradiated roots of `Picadito' lost some of its yellow tinge, but it also became darker with increased irradiation. Taste panelists reported that irradiated roots were sweeter, but these were not preferred to nonirradiated roots, due, in part, to the darkened appearance of treated samples.

Histochemistry of Mucosubstances in the Mantle of the Clam, Mercenaria mercenaria. II. MucoSubstances in the Second Marginal Fold

Histochemistry of Mucosubstances in the Mantle of the Clam, Mercenaria mercenaria. II. MucoSubstances in the Second Marginal Fold