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Profiling for volatile compounds in the Kgalagadi desert truffleBogopa, Juda January 2013 (has links)
The thesis focuses on ‘green’ sample preparation techniques that utilise minimal or no organic solvents thereby producing negligible volumes of organic waste, to ensure safety both to user and the environment. Volatile compounds were extracted and pre-concentrated from Kgalagadi desert truffles (kalaharituber) by headspace solid phase microextraction (HSSPME) and supercritical fluid extraction (SFE). PHWE was employed for the extraction of amino acids and fatty acids. Subsequent analysis of volatile compounds was carried out by gas chromatography coupled with mass spectrometry. Four types of HS-SPME fibers (PDMS 100 μm, PDMS 7 μm, Polyacrylate 85 μm, CAR/DVB/PDMS 50/30 μm) were evaluated. A total of 24 volatile compounds with a molecular weight range from 110 to 354, the most prominent peak being 2-t-Butyl-2,3-dimethyl-3-buten-1-ol (C₁₀H₂₀O, MW 156) were detected after sampling with a PDMS 100 μm fiber. Less volatile compounds were detected after SFE with CO2. A total of 16 amino acids were identified while 17 fatty acids (MW from 132.12 to 367.49) were also identified. The characteristic profile of the Kgalagadi desert truffle was found to contain mainly fatty acid methyl esters and unsaturated aliphatic hydrocarbons. The most prominent compound peaks identified were; 2-t-butyl-2,3-dimethyl- 3-buten-1-ol, disulfide, ethyl benzoic acid 2-4-dhydroxy-3,6-dimethyl-methyl ester, 8,11- octadecanoic acid methyl ester, benzoic acid, 2,4-dihydroxy-3,6-dimethyl-methyl ester, isoquinoline, 1 butyl-3,4-dihydro and 3-heptanone, 6 methyl. Optimization results indicated that fresh slices from the heart of truffles were the best to use for HS-SPME-GCMS volatile compound analysis as they showed a higher sensitivity
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Truffles Have Never Been Modern: An Actor-Network Theorization of 150 Years of French TrufficultureVan Vleet, Eric 27 March 2018 (has links)
Contemporary scholars seeking to increase Tuber Melanosporum truffle production rely almost exclusively on technological advancements to increase yields, while failing to place the cultivation of truffles, trufficulture, in its historical or local landscape contexts. In this dissertation, I describe how truffle scholars’ conceptualization of trufficulture and landscapes has changed over 150 years in France, while focusing on the French département of Lot. I examine changing relations between humans and nonhumans and how they impact truffle harvests. I analyzed the history of French trufficulture through a close reading of historic truffle manuals, archival research and the classification of remotely sensed images. Shifting from the past to the present, from July 2014-August 2016, I conducted semi-structured survey interviews with working truffle-growers (trufficulteurs) and participant observation at meetings of trufficulteurs, truffle hunts and truffle markets. I utilize actor-network theory (ANT) as both a theory and methodology. Actor-network theory allowed me to follow the impacts made by both humans and nonhumans on trufficulture. I found that truffle harvests in the 1880s dropped by 90%. Highly populated, intensively worked landscapes of viticulture, silvopastoralism and cereal cultivation created conditions suitable to truffles. By the 1870s the phylloxera aphid ravaged grapevines, which made trufficulture an important source of revenue. These advantageous conditions would not last. Post-WWI, yields fell for decades because of an ongoing rural population exodus and consequent agricultural abandonment, which promoted reforestation and closed canopy forests in Lot, France. By the 1960s, French trufficulteurs organized associations to share knowledge and promote local truffle markets to revive production. Trufficulteurs’ utilization of tractors, ‘inoculated’ plants and irrigation systems produced a new form of “modern” trufficulture. State subsidies helped trufficulteurs adopt “modern” practices, in hopes of increasing yields. “Modern” trufficulture has not dramatically increased yields. A few highly-capitalized trufficulteurs dominate production in Lot. Many others practice trufficulture as a hobby. Instead of relying on “modern” technological fixes, my findings suggest that trufficulteurs, farmers and states should reinvigorate extensive polyculture farming practices that maintain open canopy forests, which were beneficial to trufficulture in the past. Actor-network theory allowed me to rethink human and nonhuman relations, and to propose alternatives to “modern” trufficulture.
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