No description available.

Graduation date: 2006

Call number: LD2668 .T4 1959 M56

Call number: LD2668 .T4 1978 C52 / Master of Science

The effect of refluxing on the aromas of Valencia aqueous orange essences was determined through analysis by GC, MS, Osme, and by a descriptive panel. The strengths and descriptions of volatiles were investigated to determine if differences in essence aroma character and intensity existed. During production, 1 sample was subjected to reflux conditions and contained 16.2% ethanol. The other sample had not been refluxed and contained 6% ethanol. The aroma activity of volatiles was measured by Osme, a method of gas chromatography / olfactometry developed at Oregon State University. The majority of aroma active peaks were found to be present in the reflux and no reflux aqueous orange essence samples. Octanal, linalool, ethyl butanoate and 2 unknowns were the components with strongest aroma activities in both samples. Descriptive analysis was conducted with 7 trained panelists from the Food Science and Technology Department at Oregon State University. Following 12 training sessions, initial testing indicated overall intensity was the major separating attribute of essences. After 6 additional training sessions and adjustment of concentrations to yield essences of approximate equal strength, testing indicated there were no significant differences between samples. Osmegrams, GC FID chromatograms, and descriptive analysis indicated the effect of reflux produced an essence that was more concentrated. Although refluxing concentrated individual volatiles to different levels, character differences other than those associated with concentration were minimal. / Graduation date: 1996

Fresh ripe, cantaloupes were processed into juice and juice concentrate. Processing trials were conducted on fresh and frozen fruits with and without rind. The effects of maceration enzymes and fining agents on yield and quality were investigated. Compositional measurement included °Brix, pH, titratable acidity, formol values, ascorbic acid content, total carotenoids, sugar and nonvolatile acid profiles, browning indices and Hunter color parameters. Considerable ascorbic acid degradation occurred during processing. The high juice yield (80%) and low acidity suggest its potential use as an alternate sweetener source. Sensory evaluation by a trained panel showed that concentrating the juice samples from flesh and rind can remove the rind aroma and flavor characteristics. Juices obtained from flesh and from flesh and rind were not significantly different (p [less than or equal to] 0.05) except for overall intensity and fresh fruit flavor characters. Single strength juice was significantly different (p [less than or equal to] 0.05) from concentrate on most aroma and flavor characters. / Graduation date: 1991

Copies of author's previously published articles inserted. Bibliography: leaves 121-144. This study investigates the site of biosynthesis of flavour compounds in the grapevine. Most of the secondary metabolites, including flavour compounds, are glycosylated and stored in plant tissues as glycosides. The chemical properties of these compounds, especially their water solubility, suggests that glycosides might be forms of translocated secondary metabolites in plants.

This work set out to examine the methodologies of dry hopping, compare different hop materials, and look at the extraction behavior of different types of hop compounds. This work consists of two discrete studies, where the first study informed the design of the second. The first study measured the concentrations of hop aroma compounds extracted from Cascade hops during dry hopping using a model beer system devoid of malt, yeast aromas, and hops. Cascade hops pelletized by four different processors yielded different particle size distributions and pellet densities. These pellets were dosed into a degassed medium (water, 6% v/v ethanol, pH 4.2) and the hop aroma extraction was measured periodically over a one week period. Solid phase micro-extraction (SPME) followed by gas chromatography (GC-FID) was used to analyze the levels of aroma compounds in the extraction medium. Variation in the hop pellet physical properties did not significantly impact the extraction rate of hop volatiles such as linalool, geraniol, limonene and myrcene with one exception. One treatment showed an increased absolute concentration of geraniol. Separately, dry hop aroma extraction was measured over a short time (1 day) at room temperature in an unhopped beer using small-scale (1L), stirred vessels. Irrespective of the hop form (whole or pellet), the concentrations of hydrocarbon terpenes peaked between 3 and 6 hours and subsequently declined, while the concentrations of terpene alcohols continued to increase throughout the 24 hour dry hop extraction. The rate of hop aroma extraction did not appear to be significantly influenced by hop pellet properties and occurred rather rapidly regardless of the hop form. The second study examined the extraction of hop aroma compounds during a pilot brewery scale (~4hL) dry hop treatment. Dry hop treatments consisted of whole cone hops and pellet hops (Cascade cultivar, 2011 harvest) which were dosed into cylindroconical vessels which were either stirred with a pump or left quiescent. Samples were taken for GC-FID and HPLC analysis as well as sensory evaluation at various time points between 30 minutes and 12 days. Polyphenol and alpha acid extraction was highest in a stirred system dosed with pellets. Hop aroma compound extraction was also the highest in the stirred system utilizing pellet hops. The sensory panel rated the stirred pellet samples as having the highest hop aroma, bitterness, and astringency. The results showed that hop flavor from dry hopping can be readily achieved with much shorter contact time than the current 4-12 day industry practice. / Graduation date: 2013

Graduation date: 1995

No description available.