Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
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Master Thesis Utilization of Wine Waste for Fermentative Processes(Izmir Institute of Technology, 2013) Bayrak, Emrah; Büyükkileci, Ali Oğuz; Büyükkileci, Ali Oğuz; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyGrape pomace is generally considered as most valuable waste of winemaking process. Two different grape types of Syrah (red) and Muscat (white) were collected in the middle of the harvest season after pressing steps of both red and white wine making process Carbohydrate content of grape pomace was hydrolysed by enzymatic and acid hydrolysis. After screening possible fermentable sugars of grape pomace lactic acid fermentation were performed from grape pomace suspension and liquid extract phase. Lactic acid fermentation by Lactobacillus casei showed that grape pomace can be used as a substrate for lactic acid production. Different solid loadings and yeast extract concentrations effect the lactic acid production yield from grape pomace. Enzymatic hydrolysis was performed to hydrolyse pectin, cellulose and hemicellulose of grape pomace. Commercial pectinase, cellulase and β-glucosidase were supplemented into grape pomace suspensions at different concentrations. Maximum hydrolysed glucose and xylose from extracted solid phase of grape pomace were calculated as 8.93 ± 0.21 and 4.52 ± 0.11 % of total solid. Furthermore, acid hydrolysis showed that two stages acid hydrolysis is more efficient in releasing glucose from extracted solid phase of grape pomace but dilute acid hydrolysis is also more efficiency on hydrolysis of xylose and arabinose. Exo-polygalacturonase production from grape pomace was conducted using different filamentus fungi, namely Aspergillus sojae, Rhizopus oryzae and Aspergillus niger but no significant enzyme activity was obtained. Maximum 84 % of fermentable sugar in dry grape pomace was converted to lactic acid by L. casei. Effect of yeast extract researches designated that commercial yeast (bakers’ yeast) can be used as nitrogen source instead of yeast extract and 10 g/l of yeast extract was the most suitable concentration for lactic acid production from grape pomace by L.casei. This study showed the potential of the grape pomace for fermentative processes.Master Thesis Varietal Classification and Prediction of Chemical Parameters of Turkish Wines by in Frared Spectroscopy(Izmir Institute of Technology, 2010) Öztürk, Burcu; Özen, Fatma Banu; Özen, Fatma Banu; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyThis study was performed with the aim of varietal classification of mono-varietal Turkish wines and development of models to predict basic enological parameters from mid-IR spectra with the use of chemometric methods. Mid-infrared (MIR) spectroscopy combined with multivariate data analysis was employed to make a varietal classification of commercial Turkish wines (Boğazkere, Cabarnet Sauvignon, Çalkarası, Kalecik Karası, Merlot, Öküzgözü, Papazkarası, Shiraz, Emir, Misket, Narince, Sultaniye and Chardonnay) from 2006 and 2007 vintages. Wine samples (n.79) including red, rose and white wines were scanned in the mid-IR region (4000-650 cm-1) and three spectral regions (965-1565 cm-1, 1700-1900 cm-1 and 2800-3040 cm-1) were used to classify wines on the basis of grape variety. The principal component analysis (PCA) was applied to the spectral data of the wine samples. Although a clear classification could not be achieved according to varieties, almost complete classification of red and white wines was observed. For the quantification analysis, a total of eleven enological parameters, including total phenol and anthocyanin content, pH, brix, titratable acidity, colour intensity (CI), tint, yellow%, red%, blue% and the proportion of red colour produced by anthocyanins (dA%) were determined with analytical reference methods. Correlation between the results of the reference methods and MIR spectral data was tested with partial least square (PLS) regression analysis and prediction models were developed with the use of these correlations. The calibration and validation sets were established to evaluate the predictive ability of the models. As a result of PLS analysis, the best models were developed for total phenols and CI with excellent predictions (R2.0.93 and 0.89, respectively and residual predictive deviation RPD.3.68 and 3.83, respectively). The model of pH determination and yellow% gave a good prediction (R2.0.85 and 0.85, respectively and RPD.2.7 and 2.04, respectively).