An untitled manuscript --- A Novel

Thesis (M.A.)--Boston University PLEASE NOTE: p. 60 is missing from the thesis

Research Note: Total Free Sulphydryls of Several White and Red Wines

Total free sulphydryl groups were assessed in several white and red wines. Ellman’s method was adaptedto wine samples for the determination of total –SH groups. Total –SH groups of white wines, as glutathione,were in the range of 315 to 734 and of red wines in the range of 163 to 467 mg/L. In most cases, white winesexhibited higher values than red wines. The high total sulphydryls of white and red wines indicate theirpotential contribution to wine antioxidant capacity

Decrease of Wine Volatile Aroma Esters by Oxidation

The effect of oxidation on the levels of wine volatile aroma esters was studied. Chardonnay wine wasbottled either in the presence of nitrogen or air in the headspace. Moreover, Fe II was added to the wineand the bottles were closed in the presence of air. Absorbance values were recorded at 420 nm (browningindex), while volatile esters were evaluated during storage using SPME/GC-MS. During wine storage ofup to nine months, wines bottled in the presence of air exhibited higher browning indexes and lowerlevels of several esters, such ethyl acetate, isoamyl acetate, ethyl hexanoate, ethyl octanoate and ethyldecanoate, in comparison to wines bottled under nitrogen. Addition of Fe II led to higher browning indexesand lower levels of several esters during wine storage. In addition, Fe II was added along with H2O2 toChardonnay wine and the bottles were closed in the presence of air. These additions led to wines withhigher browning indexes and lower levels of several esters during wine storage up to 40 days. The presentresults demonstrate that wine volatile aroma esters can be decreased by oxidation under semi-oxidativeand forced oxidative conditions. As a result, oxidation should be taken into account in the decrease ofaroma esters during wine storage

Sprečavanje razgradnje hlapljivih estera i terpena tijekom skladištenja vina i pripravka sličnog vinu dodatkom fenolnih ekstrakata

The effect of red wine phenolic extracts on the stability of wine volatile esters and terpenes was examined. Muscat (white) and Xinomavro (red) wines were enriched with each extract at 120 or 200 mg/L, and stored in open bottles at 20 °C for 3 and 2.5 days, respectively. Moreover, a model wine medium containing isoamyl acetate, ethyl hexanoate and linalool was enriched with each extract at 100 mg/L, and stored in sealed bottles at 20 °C for 45–90 days. All samples were analysed for volatiles using SPME along with GC-MS analysis. Phenolic composition of wine extracts was determined using HPLC-DAD. No effect on the concentration of any volatiles was observed as a result of the addition of each extract in each wine or the model medium. A wine extract rich in phenolic acids and another one rich in anthocyanins and flavanols inhibited the decrease of volatile esters and terpenes in one or both wines and the model medium. Among them were several important for the aroma of wine such as ethyl acetate, isoamyl acetate, ethyl hexanoate, ethyl octanoate, ethyl decanoate and linalool. The results presented here indicate that wine phenolic acids, and anthocyanins or flavanols may be taken into account as potent inhibitors of the disappearance of volatile esters and terpenes in wines.Istražen je utjecaj fenolnih ekstrakata crnog vina na stabilnost hlapljivih estera i terpena u vinu. Muškat (bijelo vino) i Xinomavro (crno vino) obogaćeni su s po 120 ili 200 mg/L ekstrakta i skladišteni u otvorenim bocama tijekom 3 odnosno 2,5 dana pri 20 °C. Pripravak sličan vinu, koji sadrži izoamilacetat, etilheksanoat i linalol, također je obogaćen s 100 mg/L fenolnog ekstrakta, te skladišten u zatvorenim bocama pri 20 °C tijekom 45-90 dana. Hlapljive komponente svih uzoraka analizirane su SPME i GC-MS analizom. Fenolni sastav vinskih ekstrakata određen je HPLC-DAD metodom. Dodatkom fenolnih ekstrakata nije zabilježena promjena koncentracije hlapljivih sastojaka u vinima i pripravku sličnom vinu. Vinski ekstrakt bogat fenolnim kiselinama i drugi bogat antocijanima i flavanolom smanjili su razgradnju hlapljivih estera i terpena u vinu i pripravku, prije svega spojeva važnih za aromu vina, kao što su etilacetat, izoamilacetat, etilheksanoat, etiloktanoat, etildekanoat i linalol. Rezultati pokazuju da bi se fenolne kiseline, antocijanini i flavanoli iz vina mogli upotrijebiti za inhibiciju razgradnje hlapljivih estera i terpena tijekom skladištenja vina

Protection of Aroma Volatiles in a Red Wine with Low Sulphur Dioxide by a Mixture of Glutathione, Caffeic Acid and Gallic Acid

The levels of several esters and other volatiles in Merlot-Cabernet Sauvignon blend red wines with typicalsulphur dioxide (35 mg/L), with low sulphur dioxide (25 mg/L), and with low sulphur dioxide (25 mg/L)plus a mixture of antioxidants (glutathione 20 mg/L, caffeic acid 60 mg/L and gallic acid 20 mg/L), wereevaluated at bottling, and after 18 and 36 months of ageing. Most volatiles decreased during wine storage.At bottling and after 18 months of storage, all three wines exhibited similar levels of volatiles. After 36months of storage, wines with low sulphur dioxide exhibited lower levels of many volatiles, such as ethylacetate, ethyl hexanoate, ethyl octanoate and 2-phenylethanol. On the other hand, wines with low sulphurdioxide plus the mixture of antioxidants exhibited similar levels of most volatiles in comparison with wineswith typical sulphur dioxide. The present results indicate that a mixture of glutathione, caffeic acid andgallic acid can protect esters and other volatiles in young red wine with low sulphur dioxide, and canreplace part of sulphur dioxide typically used

Sensitivity of Seed Germination to Salt Stress in Teff [Eragrostis tef (Zucc.) Trotter]

Teff is an annual grass originated in Ethiopia, grown for both human food and animal feed. Salinity and moisture stress are the main limiting factors of agricultural development on arid and semi-arid regions. The aim of this study was to investigate the effect of salinity due to NaCl on germination of teff. A set of experiments was conducted under a completely randomized design with four replications of 200 seeds at two different suboptimal germination temperatures (15 and 25 °C) in the dark for 10 days. In order to create salt stress conditions during the germination process, seven solutions were used (0 as control, 80, 160, 240 and 320, 400 and 480 mM NaCl). The germination performance was evaluated by final germination percentage and mean germination time. The presence of NaCl reduced germination, especially above 240 mM for 15 °C and 400 mM for 25 °C. The mean germination time increased with higher NaCl levels