Search results for " Organic acids"
showing 5 items of 5 documents
Modulation of geraniol metabolism during alcohol fermentation
2004
J. Inst. Brew. 110(3), 213–219, 2004 Geraniol is the main monoterpenol present in Gewurtztraminer white grapes and in some red aromatic grapes from northern Italy. During fermentation, the geraniol concentration showed a dramatic drop and a small amount was transformed into linalool and -terpineol by an acid catalysed chemical reaction. Yeast are responsible for changing most of the geraniol to citronellol through enzymatic reactions. The final aroma of wine is due mainly to both the untransformed geraniol and the formed citronellol. In this study, competition between the geraniol-citronellol transformation and another metabolic process, in which according to our hypothesis sterol biosynthe…
Recovery of anthocyanins from eggplant peel
2009
Abstract Tartaric and malic acid solutions were tested to extract anthocyanins from eggplant peel by a discontinuous process to obtain a natural red colorant. Extraction optimization was carried out, using different solvents, acid concentration, temperature, time of extraction and solvent-to-solid ratio as independent variables. Tartaric acid was more efficient than malic acid in both extraction yield and rate. Comparative tests were carried out using acidified ethanol as solvent. Delphinidin-3-rutinoside was extracted and identified as the major anthocyanin in eggplant peel. Concentration of different extracts from eggplant peel was carried out using EXA-31, a methacrylic food grade resin,…
Comparative Chemical Compositions of Fresh and Stored Vesuvian PDO "Pomodorino Del Piennolo" Tomato and the Ciliegino Variety
2018
The Vesuvian Piennolo cherry tomato (Lycopersicon esculentum Miller) (PdP) is an old and typical variety grown in the Campania region (Italy). PdP is referred to as a long-storage tomato due to its thick and coriaceous skin that allows long post-harvest storage and it has been granted Protected Designation of Origin (PDO) status since 2009. In this study, the chemical composition, focusing in particular on organic acids, antioxidant molecules and volatile compounds, were investigated in PdP and compared to another typical variety in Campania, the Ciliegino tomato (CIL). Chemical characterization was evaluated for both the CIL and PdP varieties during storage in the same environmental condit…
Increase of trans-resveratrol in typical Sicilian wine using β-Glucosidase from various sources
2008
β-Glucosidase (EC 3.2.1.21) (β-G) from different sources were tested to increase the trans-resveratrol in some Sicilian wines by hydrolysing resveratrol glucoside. β-G from Aspergillus niger mould was tested as a crude and purified enzyme, and compared with the same enzyme from Saccharomyces cerevisiae yeast. Specific purification served to eliminate collateral enzyme activities so that β-G could be used simply and economically. Aspergillus niger β-G produced trans-resveratrol increases of up to 75%, with no change in physico-chemical properties and bouquet, and an increase in health and nutritional properties. S. cerevisiae β-G raised free-terpenol levels, but impaired wine colour due to a…
Modified Donnan phenomena in polyaniline with poly(vinyl sulphonate) chains
1993
We develop a physical model, based on the modified Donnan phenomena ideas introduced previously by the authors, to describe the acid doping of the conducting polymer polyaniline. The theory is motivated by the experimental work of Asturias et al. [Ber. Bunsenges. Phys. Chem. 95, 1381 (1991)]. Good agreement between theory and experiment is found.