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| 2. |
- Smith, Kevin W., et al.
(author)
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Slow recrystallization of tripaimitoylglycerol from MCT oil observed by H-2 NMR
- 2007
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In: Journal of Agricultural and Food Chemistry. - : American Chemical Society (ACS). - 0021-8561 .- 1520-5118. ; 55:21, s. 8585-8588
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Journal article (peer-reviewed)abstract
- The crystallization and recrystallization of fats have a significant impact on the properties and quality of many food products. While crystallization has been the subject of a number of studies using pure triacylglycerols (TAG), recrystallization in similarly pure systems is rarely studied. In this work, percleuterated tripalmitoylglycerol (H-2-PPP) was dissolved in medium chain triacylglycerol oil (MCT) to yield a saturated solution. The solution was heated to cause partial melting of the solid and dissolution of the molten fraction of H-2-PPP in MCT and was then cooled to the original temperature to induce recrystallization from the supersaturated solution. H-2 NMR was used to monitor the disappearance of H-2-PPP from the solution and showed that recrystallization occurred in two steps. The first step was rapid, taking place over a few minutes, and accounted for more than two-thirds of the total recrystallization. The second step was much slower, taking place over a remarkably long timescale of hours to days. It is proposed that dissolution occurs from all parts of the crystals, leaving an etched and pitted surface. The first step of crystallization is the infilling of these pits, while the second step is the continued growth on the smoothed crystal faces.
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| 3. |
- Ayub, Rabia, et al.
(author)
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Triplet State Baird Aromaticity in Macrocycles : Scope, Limitations, and Complications
- 2021
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In: Journal of Physical Chemistry A. - : American Chemical Society. - 1089-5639 .- 1520-5215. ; 125:2, s. 570-584
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Journal article (peer-reviewed)abstract
- The aromaticity of cyclic 4nπ-electron molecules in their first ππ∗ triplet state (T1), labeled Baird aromaticity, has gained growing attention in the past decade. Here we explore computationally the limitations of T1 state Baird aromaticity in macrocyclic compounds, [n]CM's, which are cyclic oligomers of four different monocycles (M = p-phenylene (PP), 2,5-linked furan (FU), 1,4-linked cyclohexa-1,3-diene (CHD), and 1,4-linked cyclopentadiene (CPD)). We strive for conclusions that are general for various DFT functionals, although for macrocycles with up to 20 π-electrons in their main conjugation paths we find that for their T1 states single-point energies at both canonical UCCSD(T) and approximative DLPNO-UCCSD(T) levels are lowest when based on UB3LYP over UM06-2X and UCAM-B3LYP geometries. This finding is in contrast to what has earlier been observed for the electronic ground state of expanded porphyrins. Yet, irrespective of functional, macrocycles with 2,5-linked furans ([n]CFU's) retain Baird aromaticity until larger n than those composed of the other three monocycles. Also, when based on geometric, electronic and energetic aspects of aromaticity, a 3[n]CFU with a specific n is more strongly Baird-aromatic than the analogous 3[n]CPP while the magnetic indices tell the opposite. To construct large T1 state Baird-aromatic [n]CM's, the design should be such that the T1 state Baird aromaticity of the macrocyclic perimeter dominates over a situation with local closed-shell Hückel aromaticity of one or a few monocycles and semilocalized triplet diradical character. Monomers with lower Hückel aromaticity in S0 than benzene (e.g., furan) that do not impose steric congestion are preferred. Structural confinement imposed by, e.g., methylene bridges is also an approach to larger Baird-aromatic macrocycles. Finally, by using the Zilberg-Haas description of T1 state aromaticity, we reveal the analogy to the Hückel aromaticity of the corresponding closed-shell dications yet observe stronger Hückel aromaticity in the macrocyclic dications than Baird aromaticity in the T1 states of the neutral macrocycles. © 2021 The Authors.
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| 4. |
- Kang, W., et al.
(author)
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Chemical and sensory impacts of Accentuated Cut Edges (ACE) grape must polyphenol extraction technique on shiraz wines
- 2020
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In: Foods. - : MDPI AG. - 2304-8158. ; 9:8
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Journal article (peer-reviewed)abstract
- Accentuated Cut Edges (ACE) is a recently developed grape must extraction technique, which mechanically breaks grape skins into small fragments but maintains seed integrity. This study was the first to elucidate the effect of ACE on Shiraz wine's basic chemical composition, colour, phenolic compounds, polysaccharides and sensory profiles. A further aim was to investigate any potential influence provided by ACE on the pre-fermentation water addition to must. ACE did not visually affect Shiraz wine colour, but significantly enhanced the concentration of tannin and total phenolics. Wine polysaccharide concentration was mainly increased in response to the maceration time rather than the ACE technique. ACE appeared to increase the earthy/dusty flavour, possibly due to the different precursors released by the greater skin breakage. The pre-fermentation addition of the water diluted the wine aromas, flavours and astringency profiles. However, combining the ACE technique with water addition enhanced the wine textural quality by increasing the intensities of the crucial astringent wine quality sub-qualities, adhesive and graininess. Furthermore, insights into the chemical factors influencing the astringency sensations were provided in this study. This research indicates that wine producers may use ACE with pre-fermentation water dilution to reduce the wine alcohol level but maintain important textural components. © 2020 by the authors.
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| 5. |
- Kang, W., et al.
(author)
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Dynamic characterization of wine astringency profiles using modified progressive profiling
- 2019
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In: Food Research International. - : Elsevier Ltd. - 0963-9969 .- 1873-7145. ; 120, s. 244-254
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Journal article (peer-reviewed)abstract
- Wine astringency is important for quality and consumer acceptance. Perception of this mouthfeel is temporal and can be separated further into unique textural sub-qualities. Quantitative data on these astringent sub-qualities in wine however are poorly understood. The aim of this study was to characterize the dynamic astringency profiles of 13 Australian commercial red wines and 2 rosés made from 11 grape varieties using modified progressive profiling by a trained sensory panel (n = 8). Seven attributes generated and defined by the panel (overall astringent intensity and 6 sub-qualities: pucker, mouth coat, dry, grippy, adhesive and graininess) were scored at six time periods (each lasting 10 s), with 20 s gap between each time period. Attributes were rated on 15 cm scales with anchors at 10 and 90% and samples were evaluated in duplicate. The wine composition as well as phenolic profiles were determined. Intensities of astringent sub-qualities were correlated with overall intensity, but the sub-quality profiles at a specific evaluation period and the progression of an attribute varied differently depending on the wine. The discrimination of wines at each time interval was dependent on attribute, and the relative importance of each astringent sub-quality varied at different evaluation periods. Correlations between mouthfeel attributes and chemical measures were established. This study demonstrated the utilisation of modified progressive profiling for wine astringency evaluation, providing a tool to capture quantitative data on astringent sub-qualities in wine.
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| 6. |
- Kang, W., et al.
(author)
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Potato protein fining of phenolic compounds in red wine : A study of the kinetics and the impact of wine matrix components and physical factors
- 2019
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In: Molecules. - : MDPI AG. - 1431-5157 .- 1420-3049. ; 24:24
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Journal article (peer-reviewed)abstract
- Producing wines within an acceptable range of astringency is important for quality and consumer acceptance. Astringency can be modified by fining during the winemaking process and the use of vegetable proteins (especially potato proteins) as fining agents has gained increasing interest due to consumers’ requirements. The research presented was the first to investigate the effect of a potato protein dose on the kinetics of tannin and phenolic removal compared to gelatin for two unfined Cabernet Sauvignon wines. To further understand the results, the influence of the wine matrix and fining parameters (including pH, ethanol concentration, sugar concentration, temperature, and agitation) were tested according to a fractional 25-1 factorial design on one of the Cabernet Sauvignon wines using potato proteins. The results from the factorial design indicate that potato protein fining was significantly influenced by wine pH, ethanol concentration, fining temperature as well as an interaction (pH × ethanol) but not by sugar content or agitation. Insights into the steps required for the optimisation of fining were gained from the study, revealing that potato protein fining efficiency could be increased by treating wines at higher temperatures (20 ◦C, rather than the conventional 10–15 ◦C), and at both a lower pH and/or alcohol concentration. © 2019 by the authors.
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| 7. |
- Ziegler, Friederike, et al.
(author)
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Expanding the concept of sustainable seafood using Life Cycle Assessment
- 2016
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In: Fish and Fisheries. - : Wiley. - 1467-2960 .- 1467-2979. ; 17:4, s. 1073-1093
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Journal article (peer-reviewed)abstract
- Fisheries management and sustainability assessment of fisheries more generally have recently expanded their scope from single-species stock assessment to ecosystem-based approaches, aiming to incorporate economic, social and local environmental impacts, while still excluding global-scale environmental impacts. In parallel, Life Cycle Assessment (LCA) has emerged as a widely used and recommended framework to assess environmental impacts of products, including global-scale impacts. For over a decade, LCA has been applied to seafood supply chains, leading to new insights into the environmental impact of seafood products.We present insights from seafood LCA research with particular focus on evaluating fisheries management, which strongly influences the environmental impact of seafood products. Further, we suggest tangible ways in which LCA could be taken up in management. By identifying trade-offs, LCA can be a useful decision support tool and avoids problem shifting from one concern (or activity) to another. The integrated, product-based and quantitative perspective brought by LCA could complement existing tools. One example is to follow up fuel use of fishing, as the production and combustion of fuel used dominates overall results for various types of environmental impacts of seafood products, and is also often linked to biological impacts of fishing. Reducing the fuel use of fisheries is therefore effective to reduce overall impacts. Allocating fishing rights based on environmental performance could likewise facilitate the transition to low-impact fisheries. Taking these steps in an open dialogue between fishers, managers, industry, NGOs and consumers would enable more targeted progress towards sustainable fisheries.
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