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Flavour of wine treated with toasted New Zealand woodsMahajan, Ishita January 2008 (has links)
The traditional wood used to make barrels destined for use in the world wide wine industry is oak. However, oak chips and shavings can substitute for barrels to add flavour to wine and are very much more cost effective. As with the heat treatment of barrels, oak chips are toasted before use. This serves to pyrolyse lignin and hemicellulose, generating families of compounds that impart desirable flavours to wine. Other woods are very occasionally used in wine barrel construction, but no chips other than oak chips have been used to flavour wine. This is surprising given that all woods contain lignin and hemicellulose, the composition of which will vary perhaps usefully from species to species. The 12 woods used in this research, including American oak, were chosen on several criteria: botanical similarly to oak, exclusivity to New Zealand, and historical association with New Zealand. The woods were cut to chips measuring about 10 x 20 x 2.5 mm. The moisture content was measured after dry heating to 110°C. Fresh samples of chips were heated (toasting in the context of wine) to 200°C for 2 hours, 210°C for 3 hours, called light and heavy toasting respectively. Weight loss was determined. The colour of the untreated and toasted wood chips was measured in Hunter colour space, yielding data on lightness (L*), hue angle (the basic colour) and saturation (the intensity of colour). The moisture content of oak was the lowest of all the woods. The weight loss of oak chips at 200°C was much greater than that of other woods, but the colour change did not indicate losses due to severe charring. Overall, each wood behaved in a distinctive way to the toasting treatments, with some charring much more than others. Hue was the least affected, indicating that the basic colour of the woods was little changed by toasting. Light and saturation generally decreased strongly, particularly on heavy toasting. Colour was thus being lost and less light reflected. An unoaked chardonnay was infused with toasted chips at the rate of 5 g.L-1 for two weeks at room temperature, and later decanted. At all stages exposure to air was minimised. The 25 treatments (2 x 12 plus the unwooded control) were first assessed by a panel comprising eight experienced wine tasters and 29 AUT staff members who claimed some knowledge of wine flavour. This qualitative/semi-quantitative analysis required tasters to assess the wines in terms of 12 descriptors commonly associated with oaked wines (boxes were ticked for ‘sweet oak’, ‘smokey’, ‘vanilla’ etc.), and to choose the three most liked and the three least liked. 6 Confidential A principal component analysis of a correlation matrix of descriptors was used to summarise panelist’s opinion. The first two principal components explained 53 % of the variation and served to group descriptors into four quadrants, which were each associated with different woods and toasting levels. Most liked were totara light (toast), kahikatea heavy, manuka heavy and American oak light. Macrocarpa light toast was almost universally disliked. On the basis of liking and association with New Zealand, five woods and chosen toasting levels and the control were selected for hedonic trials (1 to 9 liking scale) with 180 consumers (age range and gender were identified) in six retail wine shops. The decreasing numerical of liking by treatment was totara (6.49), control, manuka, American oak, kahikatea, radiata pine (5.47), with an overall significant effect (P < 0.001) for treatment. Tukey’s test revealed that only totara and the control treatments were outstanding (P < 0.05). Retail wine shop as a factor was marginally significant. Older consumers liked the wines more (P < 0.05), as did females (P < 0.001). There were no significant interactions between any of the factors. Because of the difficulties in sourcing totara, manuka appears to be the most viable alternative to oak as a wine flavouring in the New Zealand context.
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Impactites from the Hiawatha crater, North-West GreenlandGustafsson, Jacob January 2020 (has links)
The recent discovery of the 31-km-wide Hiawatha impact crater has raised unanswered questions about its age, impactor and highly unusual organic carbon component. Previous research suggests a fractionated iron meteorite impactor, a probable maximum 3–2.4 Ma impact age and a possible Younger Dryas impact age. The first objective in this study has been to investigate a possible link between the Cape York meteorites and the Hiawatha impact crater by comparing the chromium isotopic signature in chromite from a Cape York meteorite with the chromium isotopic signature in potential chromite from the Hiawatha impactor. The second objective has been to investigate a possible Hiawatha signature in the Younger Dryas deposits from Baffin Bay. The third objective has been to study the organic carbon component in impactites derived from the Hiawatha impact crater. Heavy mineral grains were separated from glaciofluvial sediment which contains Hiawatha impactite grains. Not a single chromite grain was found and the possible link to the Cape York meteorites could not be tested. The petrographic examination of Younger Dryas marine deposits resulted in absence of impact-related Hiawatha grains. A petrological investigation revealed that organic carbon was likely found in five of six variably shocked impactites derived from the Hiawatha impact crater. The character of the organic carbon varies between the samples and also within individual samples. Vitrinite reflectance measurements of the organic carbon in two impactites yielded low reflectance values compared to charcoalification experiments of wood. Organic particles with different reflectance in the same sample suggest that the particles had different impact histories prior to settling and becoming a rock. Diagnostic conifer cellular texture was found in at least one of the samples. The character of the organic particles in the impactites supports the suggestion in a previous study that the sources of the Hiawatha organic carbon component are unmetamorphosed surficial deposits containing dead conifer tree trunks and fine-grained layered clay and organic matter. In this study it is concluded that the apparent absence of chromite in the examined glaciofluvial sediment sample corroborates the significance of previous research which suggests that the Hiawatha impactor was an iron meteorite. The apparent absence of impact related grains in the Younger Dryas deposits suggests that although a Younger Dryas age for the Hiawatha impact crater is less likely now, the possibility remains open. The organic carbon with diagnostic conifer cellular texture in the Hiawatha impactites corroborates the conclusion in a previous study that the Hiawatha impact-related organic carbon component stems from local, thermally degraded conifer trees with a probable age of ca. 3–2.4 Ma. It is also concluded that the relatively low reflectance values of the organic carbon in the Hiawatha impactites seem to be related to the short duration of the high-temperature excursion during the hypervelocity impact event.
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