Impacts of depectinization of pear juice on alcoholic fermentation and indole formation.

Background: Recently, a producer of fermented ciders observed 'vinyl' off-odors formed during fermentation of pear juice previously depectinized at ≥ 49 °C but not if depectinized at lower temperatures. The objective of this study was to investigate the source of this spoilage and evaluate factors that affect formation.

Results: Analysis of untainted and tainted samples obtained from the producer determined the causative agent to be indole, a compound sometimes produced by yeast (Saccharomyces cerevisiae) during fermentation.

'Scarlett Spur Red Delicious' apple volatile production accompanying physiological disorder development during low pO2 controlled atmosphere storage.

Apple (Malus domestica Borkh.) fruit volatile production is regulated by a variety of factors including low oxygen storage conditions. This study examined the impact of low pO2 controlled atmospheres on 'Scarlett Spur Red Delicious' apple volatile production and disorder development.

The BioCassava plus program: biofortification of cassava for sub-Saharan Africa.

More than 250 million Africans rely on the starchy root crop cassava (Manihot esculenta) as their staple source of calories. A typical cassava-based diet, however, provides less than 30% of the minimum daily requirement for protein and only 10%-20% of that for iron, zinc, and vitamin A. The BioCassava Plus (BC+) program has employed modern biotechnologies intended to improve the health of Africans through the development and delivery of genetically engineered cassava with increased nutrient (zinc, iron, protein, and vitamin A) levels.

Effects of enhanced UV-B radiation on plant chemistry: nutritional consequences for a specialist and generalist lagomorph.

Ultraviolet-B (UV-B) radiation has been increasing in temperate latitudes in recent decades and is expected to continue rising for some time. Enhanced UV-B radiation can change plant chemistry, yet the effects of these changes on mammalian herbivores are unknown. To examine the influence of enhanced UV-B radiation on nutrition of a specialist and generalist hindgut fermenter, we measured nutritional and chemical constituents of three common North American range plants, big sagebrush (Artemisia tridentata), yarrow (Achillea millefolium), and bluebunch wheatgrass (Pseudoregneria spicata), and how these changes influenced in vitro dry matter digestibility and in vivo digestibility by pygmy rabbits (Brachylagus idahoensis) and eastern cottontails (Sylvilagus floridanus).

Influence of ethylene action, storage atmosphere, and storage duration on diphenylamine and diphenylamine derivative content of Granny Smith apple peel.

The application of diphenylamine (DPA) to prevent the apple peel disorder superficial scald can result in accumulation of a number of DPA derivatives resulting from C-nitration, C-hydroxylation, O-methylation, and N-nitrosation during fruit storage. As the presence of these compounds may be indicative of metabolic processes leading to superficial scald development, the contents of DPA and DPA derivatives were determined in fruits treated at harvest with DPA or DPA plus the ethylene action inhibitor 1-methylcyclopropene (1-MCP), which also prevents scald development. Influences of fruit maturity, storage environment, storage duration, and a 14 day poststorage ripening period on accumulation of DPA metabolites were also assessed.

Relationship of superficial scald development and alpha-farnesene oxidation to reactions of diphenylamine and diphenylamine derivatives in Cv. Granny Smith apple peel.

Cv. Granny Smith apple fruit, treated at harvest with aqueous emulsions containing diphenylamine (DPA) and DPA derivatives, were evaluated for the peel disorder superficial scald (scald) after 6 months of cold storage at 1 degrees C plus 0 or 7 days at 20 degrees C. Metabolism of these derivatives and alpha-farnesene oxidation were also evaluated after 6 months.

Analysis of volatile compounds from various types of barley cultivars.

We identified volatile compounds of barley flour and determined the variation in volatile compound profiles among different types and varieties of barley. Volatile compounds of 12 barley and two wheat cultivars were analyzed using solid phase microextraction (SPME) and gas chromatography. Twenty-six volatiles comprising aldehydes, ketones, alcohols, and a furan were identified in barley.

Evaluation of diphenylamine derivatives in apple peel using gradient reversed-phase liquid chromatography with ultraviolet-visible absorption and atmospheric pressure chemical ionization mass selective detection.

A method was developed for extracting, identifying, and quantifying diphenylamine (DPA) derivatives in the peel of DPA-treated apples using gradient reversed-phase liquid chromatography with ultraviolet-visible absorption and atmospheric pressure chemical ionization detection (LC-UV-vis-APCI-MS). Compounds routinely analyzed using this method included hydroxylated, nitrosated, nitrated, and methoxylated diphenylamine derivatives. Analysis of peel treated with 0-8 g L(-1) DPA showed that peel DPA content was a limiting factor in derivative production and that recovery of most compounds over this range was linear.

Ultraviolet-B radiation alters phenolic salicylate and flavonoid composition of Populus trichocarpa leaves.

We investigated foliar phenolic composition of field- and greenhouse-grown Populus trichocarpa Torr. & A. Gray (black cottonwood) ramets subjected to near zero (0x), ambient (1x) or twice ambient (2x) concentrations of biologically effective ultraviolet-B (UV-B) radiation.

Biosynthetic origin of geosmin in red beets (Beta vulgaris L.).

Geosmin provides the characteristic but sometimes undesirable "earthy" flavor to red table beets. To date, it is not known whether geosmin is a byproduct of beet metabolism or synthesized by soil-borne microorganisms and taken up by the beets during maturation. Analysis of mature beet roots revealed that peels contained 6 times the amount of geosmin compared to the bodies and cores.

Quantitative determination of geosmin in red beets (Beta vulgaris L.) using headspace solid-phase microextraction.

An improved analytical method for the determination of geosmin in red beets was developed using headspace solid-phase microextraction (HSPME). Volatiles of beet juice were extracted in headspace for 2 h using a polydimethylsiloxane/divinylbenzene fiber, thermally desorbed from the fiber, and analyzed by gas chromatography. The HSPME method was determined to be suitable for geosmin analysis as evidenced by high relative recovery (99.

Alteration of foliar flavonoid chemistry induced by enhanced UV-B radiation in field-grown Pinus ponderosa, Quercus rubra and Pseudotsuga menziesii.

Chromatographic analyses of foliage from several tree species illustrate the species-specific effects of UV-B radiation on both quantity and composition of foliar flavonoids. Pinus ponderosa, Quercus rubra and Pseudotsuga menziesii were field-grown under modulated ambient (1x) and enhanced (2x) biologically effective UV-B radiation. Foliage was harvested seasonally over a 3-year period, extracted, purified and the flavonoid fraction applied to a mu Bondapak/C(18) column HPLC system sampling at 254 nm.