Food Engineering / Gıda Mühendisliği

Permanent URI for this collectionhttps://hdl.handle.net/11147/12

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Publisher: search.filters.publisher.American Society for Enology and Viticulture

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  • Article
    Citation - WoS: 1
    Citation - Scopus: 1
    Temperature and Glycerol Formation: a Proposal To Explain the Causal Relationship Based on Glycolytic Enzyme Activities
    (American Society for Enology and Viticulture, 2019) Büyükkileci, Ceylan; Batur, Ayşem; Büyükkileci, Ali Oğuz; Hamamcı, Haluk; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    Most yeast strains produce glycerol in larger quantities when cultivated at higher temperatures, which likely explains why red wines contain higher amounts of glycerol than white wines. In this work, we used a kinetic and thermodynamic approach to suggest a mechanistic explanation for this phenomenon. We began with a glycolytic model of the kinetics of the individual enzymes. The effects of temperature and ethanol on the apparent kinetics of individual enzymes were then determined and incorporated into the model. The activation energy for each enzyme was determined with the Arrhenius equation. The enzymes in the upper part of the glycolytic pathway were found to be more dependent on the temperature than those in the lower part. The model, as improved by these changes, could qualitatively simulate the ethanol and glycerol production curves and the production of more glycerol at higher temperatures. We propose that the differences in the temperature dependence of the enzymes around the glycerol branch are the reason for glycerol accumulation at higher temperatures.
  • Article
    Citation - WoS: 22
    Citation - Scopus: 23
    Characterization and Classification of Turkish Wines Based on Elemental Composition
    (American Society for Enology and Viticulture, 2014) Şen, İlknur; Tokatlı, Figen; Tokatlı, Figen; Şen, İlknur; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    Commercial wines from 13 native and nonnative varieties in Turkey were analyzed for their elemental composition. Wines from four vintages (2006-2009) were analyzed by inductively coupled plasma with atomic emission spectrometry and mass spectroscopy (ICP-AES and ICP-MS) followed by multivariate statistics to study vintage, varietal, and regional differences. According to the partial least squares-discriminant analysis, wines from western regions could be discriminated with their higher Pb content. The red wines of two native grapes, Boǧazkere and Öküzgözü, were separated from the remaining varieties based on their high Ca and low B and Cu levels. Öküzgözü wines were different from Syrah and Cabernet Sauvignon wines. Similarly, native Emir wines showed differences from Muscat wines. The effective variables for discrimination analysis were natural minerals (Sr, Li, Al, Ba, and B) and minerals originating from agricultural activities, processing, or pollution (Ca, Cu, Mg, Co, Pb, and Ni). Characteristics of Turkish wines from native and nonnative grape varieties such as Cabernet Sauvignon, Merlot, Syrah, and Chardonnay were defined in terms of their mineral content for the first time.